2009-06-28 Tatsuhiro Tsujikawa <t-tujikawa@users.sourceforge.net>

Rewritten DownloadContext and removed SingleFileDownloadContext and BtContext and its derived classes. BitTorrent specific attributes are now set by DownloadContext::setAttribute() with key bittorrent::BITTORRENT. * src/AbstractBtMessage.cc * src/AbstractBtMessage.h * src/AbstractCommand.cc * src/AbstractCommand.h * src/AbstractProxyRequestCommand.cc * src/AbstractProxyResponseCommand.cc * src/ActivePeerConnectionCommand.cc * src/ActivePeerConnectionCommand.h * src/AnnounceList.cc * src/BtCheckIntegrityEntry.cc * src/BtConstants.h * src/BtContext.h: Removed * src/BtDependency.cc * src/BtExtendedMessage.cc * src/BtPieceMessage.cc * src/BtPieceMessage.h * src/BtPostDownloadHandler.cc * src/BtRegistry.cc * src/BtRegistry.h * src/BtSetup.cc * src/CheckIntegrityCommand.cc * src/CheckIntegrityEntry.cc * src/ChecksumCheckIntegrityEntry.cc * src/ConsoleStatCalc.cc * src/ContentTypeRequestGroupCriteria.cc * src/DHTGetPeersCommand.cc * src/DHTGetPeersCommand.h * src/DHTPeerLookupTask.cc * src/DHTPeerLookupTask.h * src/DHTTaskFactory.h * src/DHTTaskFactoryImpl.cc * src/DHTTaskFactoryImpl.h * src/DefaultBtAnnounce.cc * src/DefaultBtAnnounce.h * src/DefaultBtContext.cc: Removed * src/DefaultBtContext.h: Removed * src/DefaultBtInteractive.cc * src/DefaultBtInteractive.h * src/DefaultBtMessageDispatcher.cc * src/DefaultBtMessageDispatcher.h * src/DefaultBtMessageFactory.cc * src/DefaultBtMessageFactory.h * src/DefaultBtMessageReceiver.cc * src/DefaultBtMessageReceiver.h * src/DefaultBtProgressInfoFile.cc * src/DefaultBtRequestFactory.cc * src/DefaultBtRequestFactory.h * src/DefaultExtensionMessageFactory.cc * src/DefaultExtensionMessageFactory.h * src/DefaultPeerStorage.cc * src/DefaultPeerStorage.h * src/DefaultPieceStorage.cc * src/DefaultSegmentManFactory.cc * src/DiskAdaptor.cc * src/DiskAdaptor.h * src/DownloadContext.cc * src/DownloadContext.h * src/DownloadEngine.cc * src/DownloadEngineFactory.cc * src/DownloadHandler.cc * src/DownloadResult.h * src/FileAllocationCommand.cc * src/FileAllocationDispatcherCommand.cc * src/FileAllocationEntry.cc * src/FileEntry.h * src/FillRequestGroupCommand.cc * src/FtpDownloadCommand.cc * src/FtpFinishDownloadCommand.cc * src/FtpInitiateConnectionCommand.cc * src/FtpNegotiationCommand.cc * src/FtpTunnelRequestCommand.cc * src/FtpTunnelResponseCommand.cc * src/HandshakeExtensionMessage.cc * src/HandshakeExtensionMessage.h * src/HaveEraseCommand.cc * src/HttpDownloadCommand.cc * src/HttpInitiateConnectionCommand.cc * src/HttpProxyRequestCommand.cc * src/HttpProxyResponseCommand.cc * src/HttpRequest.cc * src/HttpRequest.h * src/HttpRequestCommand.cc * src/HttpResponseCommand.cc * src/HttpServerBodyCommand.cc * src/HttpServerCommand.cc * src/HttpSkipResponseCommand.cc * src/InitiateConnectionCommandFactory.cc * src/InitiatorMSEHandshakeCommand.cc * src/InitiatorMSEHandshakeCommand.h * src/IteratableChecksumValidator.cc * src/IteratableChecksumValidator.h * src/IteratableChunkChecksumValidator.cc * src/MSEHandshake.cc * src/MSEHandshake.h * src/Makefile.am * src/Makefile.in * src/Metalink2RequestGroup.cc * src/MetalinkPostDownloadHandler.cc * src/MultiDiskAdaptor.cc * src/MultiDiskAdaptor.h * src/MultiFileAllocationIterator.cc * src/MultiUrlRequestInfo.cc * src/PeerChokeCommand.cc * src/PeerChokeCommand.h * src/PeerInitiateConnectionCommand.cc * src/PeerInitiateConnectionCommand.h * src/PeerInteractionCommand.cc * src/PeerInteractionCommand.h * src/PeerReceiveHandshakeCommand.cc * src/PieceHashCheckIntegrityEntry.cc * src/RealtimeCommand.cc * src/ReceiverMSEHandshakeCommand.cc * src/RequestGroup.cc * src/RequestGroup.h * src/RequestGroupEntry.cc * src/RequestGroupMan.cc * src/SeedCheckCommand.cc * src/SeedCheckCommand.h * src/SegmentMan.cc * src/ShareRatioSeedCriteria.h * src/SingleFileDownloadContext.cc: Removed * src/SingleFileDownloadContext.h: Removed * src/SleepCommand.cc * src/StreamCheckIntegrityEntry.cc * src/TrackerWatcherCommand.cc * src/TrackerWatcherCommand.h * src/UnknownLengthPieceStorage.cc * src/Util.cc * src/Util.h * src/XmlRpcMethodImpl.cc * src/bittorrent_helper.cc * src/bittorrent_helper.h * src/download_helper.cc * src/main.cc * src/option_processing.cc * test/BitfieldManTest.cc * test/BittorrentHelperTest.cc * test/BtCancelMessageTest.cc * test/BtChokeMessageTest.cc * test/BtDependencyTest.cc * test/BtPieceMessageTest.cc * test/BtPostDownloadHandlerTest.cc * test/BtRegistryTest.cc * test/BtRejectMessageTest.cc * test/BtRequestMessageTest.cc * test/DHTPeerAnnounceStorageTest.cc * test/DefaultBtAnnounceTest.cc * test/DefaultBtContextTest.cc: Removed * test/DefaultBtMessageDispatcherTest.cc * test/DefaultBtMessageFactoryTest.cc * test/DefaultBtProgressInfoFileTest.cc * test/DefaultBtRequestFactoryTest.cc * test/DefaultExtensionMessageFactoryTest.cc * test/DefaultPeerStorageTest.cc * test/DefaultPieceStorageTest.cc * test/DirectDiskAdaptorTest.cc * test/DownloadContextTest.cc * test/DownloadHandlerFactoryTest.cc * test/DownloadHelperTest.cc * test/HandshakeExtensionMessageTest.cc * test/HttpRequestTest.cc * test/HttpResponseTest.cc * test/IteratableChecksumValidatorTest.cc * test/IteratableChunkChecksumValidatorTest.cc * test/MSEHandshakeTest.cc * test/Makefile.am * test/Makefile.in * test/Metalink2RequestGroupTest.cc * test/MetalinkPostDownloadHandlerTest.cc * test/MockBtContext.h: Removed * test/MockDHTTaskFactory.h * test/MockDownloadContext.h: Removed * test/MockPieceStorage.h * test/MultiDiskAdaptorTest.cc * test/MultiFileAllocationIteratorTest.cc * test/RequestGroupManTest.cc * test/RequestGroupTest.cc * test/SegmentManTest.cc * test/ShareRatioSeedCriteriaTest.cc * test/SingleFileDownloadContextTest.cc: Removed * test/UtilTest.cc * test/XmlRpcMethodTest.cc
author: Tatsuhiro Tsujikawa <tatsuhiro.t@gmail.com> 2009-06-28 10:37:15 +0000
committer: Tatsuhiro Tsujikawa <tatsuhiro.t@gmail.com> 2009-06-28 10:37:15 +0000
commit: 5699b675268658ea958f7c2306e19849dff9bc41 (patch)
tree: c654c18eef6f4361cccf13854895b88967aa33ea /src
parent: 90471d68050ebd05439435330e4d0dbb19c6fd1e (diff)
135 files changed, 1582 insertions, 1970 deletions
diff --git a/src/AbstractBtMessage.cc b/src/AbstractBtMessage.cc
index f2aa432b..d68d49b1 100644
--- a/src/AbstractBtMessage.cc
+++ b/src/AbstractBtMessage.cc
@@ -34,7 +34,6 @@
 /* copyright --> */
 #include "AbstractBtMessage.h"
 #include "Peer.h"
-#include "BtContext.h"
 #include "PieceStorage.h"
 #include "BtMessageValidator.h"
 #include "LogFactory.h"
@@ -73,11 +72,6 @@ AbstractBtMessage::setBtMessageValidator(const SharedHandle<BtMessageValidator>&
   this->validator = validator;
 }
 
-void AbstractBtMessage::setBtContext(const SharedHandle<BtContext>& btContext)
-{
-  this->btContext = btContext;
-}
-
 void AbstractBtMessage::setPieceStorage(const SharedHandle<PieceStorage>& pieceStorage)
 {
   this->pieceStorage = pieceStorage;
diff --git a/src/AbstractBtMessage.h b/src/AbstractBtMessage.h
index 16fa4013..588bc96e 100644
--- a/src/AbstractBtMessage.h
+++ b/src/AbstractBtMessage.h
@@ -41,7 +41,6 @@
 
 namespace aria2 {
 
-class BtContext;
 class PieceStorage;
 class Peer;
 class BtMessageDispatcher;
@@ -60,8 +59,6 @@ protected:
 
   std::string _name;
 
-  SharedHandle<BtContext> btContext;
-
   SharedHandle<PieceStorage> pieceStorage;
 
   SharedHandle<Peer> peer;
@@ -137,13 +134,6 @@ public:
 
   void setBtMessageValidator(const SharedHandle<BtMessageValidator>& validator);
 
-  void setBtContext(const SharedHandle<BtContext>& btContext);
-
-  const SharedHandle<BtContext>& getBtContext() const
-  {
-    return btContext;
-  }
-
   void setPieceStorage(const SharedHandle<PieceStorage>& pieceStorage);
 
   void setBtMessageDispatcher(const WeakHandle<BtMessageDispatcher>& dispatcher);
diff --git a/src/AbstractCommand.cc b/src/AbstractCommand.cc
index b1004a48..57f1a80a 100644
--- a/src/AbstractCommand.cc
+++ b/src/AbstractCommand.cc
@@ -36,7 +36,6 @@
 
 #include <algorithm>
 
-#include "RequestGroup.h"
 #include "Request.h"
 #include "DownloadEngine.h"
 #include "Option.h"
@@ -231,9 +230,9 @@ bool AbstractCommand::execute() {
 
 void AbstractCommand::tryReserved() {
   _requestGroup->removeServerHost(cuid);
-  if(_requestGroup->getDownloadContext()->getFileMode() == DownloadContext::SINGLE) {
+  if(_requestGroup->getDownloadContext()->getFileEntries().size() == 1) {
     const SharedHandle<FileEntry>& entry =
-      _requestGroup->getDownloadContext()->getFileEntries().front();
+      _requestGroup->getDownloadContext()->getFirstFileEntry();
     // Don't create new command if currently file length is unknown
     // and there are no URI left. Because file length is unknown, we
     // can assume that there are no in-flight request object.
diff --git a/src/AbstractCommand.h b/src/AbstractCommand.h
index ba7a7aa4..d7ced6d2 100644
--- a/src/AbstractCommand.h
+++ b/src/AbstractCommand.h
@@ -39,12 +39,12 @@
 #include "SharedHandle.h"
 #include "TimeA2.h"
 #include "FileEntry.h"
+#include "RequestGroup.h"
 
 namespace aria2 {
 
 class Request;
 class DownloadEngine;
-class RequestGroup;
 class Segment;
 class Exception;
 class SocketCore;
@@ -122,6 +122,11 @@ protected:
   const std::string& resolveProxyMethod(const std::string& protocol) const;
 
   const SharedHandle<Option>& getOption() const;
+
+  const SharedHandle<DownloadContext>& getDownloadContext() const
+  {
+    return _requestGroup->getDownloadContext();
+  }
 private:
   bool checkSocketIsReadable;
   bool checkSocketIsWritable;
diff --git a/src/AbstractProxyRequestCommand.cc b/src/AbstractProxyRequestCommand.cc
index 4fc3fadc..698f5bb4 100644
--- a/src/AbstractProxyRequestCommand.cc
+++ b/src/AbstractProxyRequestCommand.cc
@@ -45,6 +45,7 @@
 #include "CookieStorage.h"
 #include "AuthConfigFactory.h"
 #include "AuthConfig.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/AbstractProxyResponseCommand.cc b/src/AbstractProxyResponseCommand.cc
index 00520cc6..f6b1ac13 100644
--- a/src/AbstractProxyResponseCommand.cc
+++ b/src/AbstractProxyResponseCommand.cc
@@ -45,6 +45,7 @@
 #include "DlRetryEx.h"
 #include "message.h"
 #include "HttpHeader.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/ActivePeerConnectionCommand.cc b/src/ActivePeerConnectionCommand.cc
index 7c76ab4a..7f5709d8 100644
--- a/src/ActivePeerConnectionCommand.cc
+++ b/src/ActivePeerConnectionCommand.cc
@@ -36,7 +36,6 @@
 #include "PeerInitiateConnectionCommand.h"
 #include "message.h"
 #include "DownloadEngine.h"
-#include "BtContext.h"
 #include "PeerStorage.h"
 #include "PieceStorage.h"
 #include "BtRuntime.h"
@@ -48,6 +47,7 @@
 #include "SocketCore.h"
 #include "BtAnnounce.h"
 #include "RequestGroup.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
@@ -55,12 +55,10 @@ ActivePeerConnectionCommand::ActivePeerConnectionCommand
 (int cuid,
  RequestGroup* requestGroup,
  DownloadEngine* e,
- const BtContextHandle& btContext,
  time_t interval)
   :
   Command(cuid),
   _requestGroup(requestGroup),
-  _btContext(btContext),
   interval(interval),
   e(e),
   _numNewConnection(5)
@@ -130,7 +128,7 @@ void ActivePeerConnectionCommand::connectToPeer(const PeerHandle& peer)
   peer->usedBy(e->newCUID());
   PeerInitiateConnectionCommand* command =
     new PeerInitiateConnectionCommand(peer->usedBy(), _requestGroup, peer, e,
-				      _btContext, _btRuntime);
+				      _btRuntime);
   command->setPeerStorage(_peerStorage);
   command->setPieceStorage(_pieceStorage);
   e->commands.push_back(command);
diff --git a/src/ActivePeerConnectionCommand.h b/src/ActivePeerConnectionCommand.h
index d8c7c452..3f22b6a6 100644
--- a/src/ActivePeerConnectionCommand.h
+++ b/src/ActivePeerConnectionCommand.h
@@ -44,7 +44,6 @@ namespace aria2 {
 class RequestGroup;
 class DownloadEngine;
 class Peer;
-class BtContext;
 class BtRuntime;
 class PieceStorage;
 class PeerStorage;
@@ -53,7 +52,6 @@ class BtAnnounce;
 class ActivePeerConnectionCommand : public Command {
 private:
   RequestGroup* _requestGroup;
-  SharedHandle<BtContext> _btContext;
   SharedHandle<BtRuntime> _btRuntime;
   SharedHandle<PieceStorage> _pieceStorage;
   SharedHandle<PeerStorage> _peerStorage;
@@ -67,7 +65,6 @@ public:
   ActivePeerConnectionCommand(int cuid,
 			      RequestGroup* requestGroup,
 			      DownloadEngine* e,
-			      const SharedHandle<BtContext>& btContext,
 			      time_t interval);
 
   virtual ~ActivePeerConnectionCommand();
diff --git a/src/AnnounceList.cc b/src/AnnounceList.cc
index ffe97305..e63d0082 100644
--- a/src/AnnounceList.cc
+++ b/src/AnnounceList.cc
@@ -39,6 +39,7 @@
 #include "A2STR.h"
 #include "SimpleRandomizer.h"
 #include "bencode.h"
+#include "Util.h"
 
 namespace aria2 {
 
@@ -72,7 +73,7 @@ void AnnounceList::reconfigure(const BDE& announceList)
 	  elemItr != elemList.listEnd(); ++elemItr) {
 	const BDE& data = *elemItr;
 	if(data.isString()) {
-	  urls.push_back(data.s());
+	  urls.push_back(Util::trim(data.s()));
 	}
       }
       if(!urls.empty()) {
diff --git a/src/BtCheckIntegrityEntry.cc b/src/BtCheckIntegrityEntry.cc
index 3197e6c2..8aa1277c 100644
--- a/src/BtCheckIntegrityEntry.cc
+++ b/src/BtCheckIntegrityEntry.cc
@@ -40,6 +40,7 @@
 #include "DiskAdaptor.h"
 #include "prefs.h"
 #include "Option.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/BtConstants.h b/src/BtConstants.h
index 3d1b9cf9..28db953a 100644
--- a/src/BtConstants.h
+++ b/src/BtConstants.h
@@ -41,6 +41,10 @@
 
 typedef std::map<std::string, uint8_t> Extensions;
 
+#define INFO_HASH_LENGTH 20
+
+#define PIECE_HASH_LENGTH 20
+
 #define PEER_ID_LENGTH 20
 
 #define INFO_HASH_LENGTH 20
diff --git a/src/BtContext.h b/src/BtContext.h
deleted file mode 100644
index 858b11cd..00000000
--- a/src/BtContext.h
+++ /dev/null
@@ -1,97 +0,0 @@
-/* <!-- copyright */
-/*
- * aria2 - The high speed download utility
- *
- * Copyright (C) 2006 Tatsuhiro Tsujikawa
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- *
- * In addition, as a special exception, the copyright holders give
- * permission to link the code of portions of this program with the
- * OpenSSL library under certain conditions as described in each
- * individual source file, and distribute linked combinations
- * including the two.
- * You must obey the GNU General Public License in all respects
- * for all of the code used other than OpenSSL.  If you modify
- * file(s) with this exception, you may extend this exception to your
- * version of the file(s), but you are not obligated to do so.  If you
- * do not wish to do so, delete this exception statement from your
- * version.  If you delete this exception statement from all source
- * files in the program, then also delete it here.
- */
-/* copyright --> */
-#ifndef _D_BT_CONTEXT_H_
-#define _D_BT_CONTEXT_H_
-
-#include "DownloadContext.h"
-
-#include <utility>
-#include <deque>
-
-#include "IntSequence.h"
-
-namespace aria2 {
-
-class AnnounceTier;
-class RequestGroup;
-
-class BtContext:public DownloadContext {
-protected:
-  bool _private;
-public:
-  BtContext():_private(false) {}
-  
-  virtual ~BtContext() {}
-
-  virtual const unsigned char* getInfoHash() const = 0;
-
-  virtual size_t getInfoHashLength() const = 0;
-
-  virtual const std::string& getInfoHashAsString() const = 0;
-
-  virtual const std::deque<SharedHandle<AnnounceTier> >&
-  getAnnounceTiers() const = 0;
-
-  virtual void load(const std::string& torrentFile,
-		    const std::string& overrideName = "") = 0;
-
-  /**
-   * Returns the peer id of localhost, 20 byte length
-   */
-  virtual const unsigned char* getPeerId() = 0;
-
-  bool isPrivate() const
-  {
-    return _private;
-  }
-
-  virtual void computeFastSet
-  (std::deque<size_t>& fastSet, const std::string& ipaddr, size_t fastSetSize) = 0;
-  
-  virtual RequestGroup* getOwnerRequestGroup() = 0;
-
-  virtual std::deque<std::pair<std::string, uint16_t> >& getNodes() = 0;
-
-  virtual const std::string& getName() const = 0;
-
-  virtual void setFileFilter(IntSequence seq) = 0;
-};
-
-class BtContext;
-typedef SharedHandle<BtContext> BtContextHandle;
-
-} // namespace aria2
-
-#endif // _D_BT_CONTEXT_H_
diff --git a/src/BtDependency.cc b/src/BtDependency.cc
index 0109f1de..d8f5c0d3 100644
--- a/src/BtDependency.cc
+++ b/src/BtDependency.cc
@@ -37,7 +37,7 @@
 #include "Option.h"
 #include "LogFactory.h"
 #include "Logger.h"
-#include "DefaultBtContext.h"
+#include "DownloadContext.h"
 #include "RecoverableException.h"
 #include "message.h"
 #include "prefs.h"
@@ -45,6 +45,8 @@
 #include "PieceStorage.h"
 #include "DiskAdaptor.h"
 #include "File.h"
+#include "bittorrent_helper.h"
+#include "DlAbortEx.h"
 
 namespace aria2 {
 
@@ -62,39 +64,38 @@ bool BtDependency::resolve()
     RequestGroupHandle dependee = _dependee;
     // cut reference here
     _dependee.reset();
-    DefaultBtContextHandle btContext(new DefaultBtContext());
-    btContext->setDir(_dependant->getDownloadContext()->getDir());
+    SharedHandle<DownloadContext> context(new DownloadContext());
+    context->setDir(_dependant->getDownloadContext()->getDir());
     try {
-      DiskAdaptorHandle diskAdaptor = dependee->getPieceStorage()->getDiskAdaptor();
+      DiskAdaptorHandle diskAdaptor =
+	dependee->getPieceStorage()->getDiskAdaptor();
       diskAdaptor->openExistingFile();
       std::string content = Util::toString(diskAdaptor);
-
-      std::string overrideName;
-      if(Util::startsWith(_dependant->getDownloadContext()->getActualBasePath(),
-			  _dependant->getDownloadContext()->getDir())) {
-	overrideName =
-	  _dependant->getDownloadContext()->getActualBasePath().substr
-	  (_dependant->getDownloadContext()->getDir().size());
-	if(Util::startsWith(overrideName, "/")) {
-	  overrideName = overrideName.substr(1);
-	}
+      bittorrent::loadFromMemory
+	(content, context, File(dependee->getFirstFilePath()).getBasename());
+      if(context->getFileEntries().size() !=
+	 _dependant->getDownloadContext()->getFileEntries().size()) {
+	throw DL_ABORT_EX("The number of file in torrent doesn't match to"
+			  " the dependant.");
       }
-      btContext->loadFromMemory(content,
-				File(dependee->getFilePath()).getBasename(),
-				overrideName);
-      if(_dependant->getOption()->defined(PREF_PEER_ID_PREFIX)) {
-	btContext->setPeerIdPrefix
-	  (_dependant->getOption()->get(PREF_PEER_ID_PREFIX));
+      // Copy file path in _dependant's FileEntries to newly created
+      // context's FileEntries to endorse the path structure of
+      // _dependant.
+      for(std::vector<SharedHandle<FileEntry> >::const_iterator s =
+	    _dependant->getDownloadContext()->getFileEntries().begin(),
+	    d = context->getFileEntries().begin();
+	  d != context->getFileEntries().end(); ++s, ++d) {
+	(*d)->setPath((*s)->getPath());
       }
     } catch(RecoverableException& e) {
       _logger->error(EX_EXCEPTION_CAUGHT, e);
-      _logger->debug("BtDependency for GID#%d failed. Go without Bt.",
-		     _dependant->getGID());
+      _logger->info("BtDependency for GID#%d failed. Go without Bt.",
+		    _dependant->getGID());
       return true;
     }
     _logger->debug("Dependency resolved for GID#%d", _dependant->getGID());
-    _dependant->setDownloadContext(btContext);
-    btContext->setOwnerRequestGroup(_dependant.get());
+    _dependant->setDownloadContext(context);
+    context->setOwnerRequestGroup(_dependant.get());
     return true;
   } else if(_dependee->getNumCommand() == 0) {
     // _dependee's download failed.
diff --git a/src/BtExtendedMessage.cc b/src/BtExtendedMessage.cc
index afa19a35..39d61028 100644
--- a/src/BtExtendedMessage.cc
+++ b/src/BtExtendedMessage.cc
@@ -41,7 +41,6 @@
 #include "ExtensionMessageFactory.h"
 #include "PeerMessageUtil.h"
 #include "Peer.h"
-#include "BtContext.h"
 #include "DlAbortEx.h"
 #include "message.h"
 #include "Util.h"
diff --git a/src/BtPieceMessage.cc b/src/BtPieceMessage.cc
index 970a35dd..9381d6e4 100644
--- a/src/BtPieceMessage.cc
+++ b/src/BtPieceMessage.cc
@@ -47,13 +47,13 @@
 #include "Logger.h"
 #include "Peer.h"
 #include "Piece.h"
-#include "BtContext.h"
 #include "PieceStorage.h"
 #include "BtMessageDispatcher.h"
 #include "BtMessageFactory.h"
 #include "BtRequestFactory.h"
 #include "PeerConnection.h"
 #include "StringFormat.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
@@ -85,7 +85,7 @@ void BtPieceMessage::doReceivedAction() {
     peer->snubbing(false);
     peer->updateLatency(slot.getLatencyInMillis());
     PieceHandle piece = pieceStorage->getPiece(index);
-    off_t offset = (off_t)index*btContext->getPieceLength()+begin;
+    off_t offset = (off_t)index*_downloadContext->getPieceLength()+begin;
     logger->debug(MSG_PIECE_RECEIVED,
 		  cuid, index, begin, blockLength, offset, slot.getBlockIndex());
     pieceStorage->getDiskAdaptor()->writeData(block, blockLength, offset);
@@ -143,7 +143,7 @@ void BtPieceMessage::send() {
     getMessageHeader();
     peerConnection->sendMessage(msgHeader, getMessageHeaderLength());
     off_t pieceDataOffset =
-      (off_t)index*btContext->getPieceLength()+begin;
+      (off_t)index*_downloadContext->getPieceLength()+begin;
     size_t writtenLength = sendPieceData(pieceDataOffset, blockLength);
     logger->debug("msglength = %lu bytes",
 		  static_cast<unsigned long>(getMessageHeaderLength()+
@@ -176,12 +176,13 @@ bool BtPieceMessage::checkPieceHash(const PieceHandle& piece) {
   if(piece->isHashCalculated()) {
     logger->debug("Hash is available!! index=%lu",
 		  static_cast<unsigned long>(piece->getIndex()));
-    return piece->getHashString() == btContext->getPieceHash(piece->getIndex());
+    return
+      piece->getHashString()==_downloadContext->getPieceHash(piece->getIndex());
   } else {
-    off_t offset = (off_t)piece->getIndex()*btContext->getPieceLength();
+    off_t offset = (off_t)piece->getIndex()*_downloadContext->getPieceLength();
     
     return MessageDigestHelper::staticSHA1Digest(pieceStorage->getDiskAdaptor(), offset, piece->getLength())
-      == btContext->getPieceHash(piece->getIndex());
+      == _downloadContext->getPieceHash(piece->getIndex());
   }
 }
 
@@ -203,7 +204,7 @@ void BtPieceMessage::erasePieceOnDisk(const PieceHandle& piece) {
   size_t BUFSIZE = 4096;
   unsigned char buf[BUFSIZE];
   memset(buf, 0, BUFSIZE);
-  off_t offset = (off_t)piece->getIndex()*btContext->getPieceLength();
+  off_t offset = (off_t)piece->getIndex()*_downloadContext->getPieceLength();
   div_t res = div(piece->getLength(), BUFSIZE);
   for(int i = 0; i < res.quot; ++i) {
     pieceStorage->getDiskAdaptor()->writeData(buf, BUFSIZE, offset);
@@ -255,4 +256,10 @@ void BtPieceMessage::onCancelSendingPieceEvent
   } 
 }
 
+void BtPieceMessage::setDownloadContext
+(const SharedHandle<DownloadContext>& downloadContext)
+{
+  _downloadContext = downloadContext;
+}
+
 } // namespace aria2
diff --git a/src/BtPieceMessage.h b/src/BtPieceMessage.h
index 9b543035..b87cc40b 100644
--- a/src/BtPieceMessage.h
+++ b/src/BtPieceMessage.h
@@ -41,6 +41,7 @@ namespace aria2 {
 
 class Piece;
 class BtPieceMessage;
+class DownloadContext;
 
 typedef SharedHandle<BtPieceMessage> BtPieceMessageHandle;
 
@@ -51,6 +52,7 @@ private:
   uint32_t blockLength;
   unsigned char* block;
   unsigned char* msgHeader;
+  SharedHandle<DownloadContext> _downloadContext;
 
   static size_t MESSAGE_HEADER_LENGTH;
 
@@ -100,6 +102,8 @@ public:
 
   void setBlockLength(size_t blockLength) { this->blockLength = blockLength; }
 
+  void setDownloadContext(const SharedHandle<DownloadContext>& downloadContext);
+
   static BtPieceMessageHandle create(const unsigned char* data, size_t dataLength);
 
   virtual void doReceivedAction();
diff --git a/src/BtPostDownloadHandler.cc b/src/BtPostDownloadHandler.cc
index 29685e6e..5e733d75 100644
--- a/src/BtPostDownloadHandler.cc
+++ b/src/BtPostDownloadHandler.cc
@@ -33,7 +33,6 @@
  */
 /* copyright --> */
 #include "BtPostDownloadHandler.h"
-#include "DefaultBtContext.h"
 #include "prefs.h"
 #include "RequestGroup.h"
 #include "Option.h"
@@ -45,6 +44,8 @@
 #include "Util.h"
 #include "ContentTypeRequestGroupCriteria.h"
 #include "Exception.h"
+#include "DownloadContext.h"
+#include "bittorrent_helper.h"
 
 namespace aria2 {
 
@@ -64,7 +65,7 @@ void BtPostDownloadHandler::getNextRequestGroups
 {
   const SharedHandle<Option>& op = requestGroup->getOption();
   _logger->debug("Generating RequestGroups for Torrent file %s",
-		 requestGroup->getFilePath().c_str());
+		 requestGroup->getFirstFilePath().c_str());
   RequestGroupHandle rg(new RequestGroup(op, std::deque<std::string>()));
 
   std::string content;
@@ -76,14 +77,12 @@ void BtPostDownloadHandler::getNextRequestGroups
     requestGroup->getPieceStorage()->getDiskAdaptor()->closeFile();
     throw;
   }
-  DefaultBtContextHandle btContext(new DefaultBtContext());
-  btContext->setDir(requestGroup->getDownloadContext()->getDir());
-  btContext->loadFromMemory(content, File(requestGroup->getFilePath()).getBasename());
-  if(op->defined(PREF_PEER_ID_PREFIX)) {
-    btContext->setPeerIdPrefix(op->get(PREF_PEER_ID_PREFIX));
-  }
-  rg->setDownloadContext(btContext);
-  btContext->setOwnerRequestGroup(rg.get());
+  SharedHandle<DownloadContext> context(new DownloadContext());
+  context->setDir(requestGroup->getDownloadContext()->getDir());
+  bittorrent::loadFromMemory(content, context,
+			     File(requestGroup->getFirstFilePath()).getBasename());
+  rg->setDownloadContext(context);
+  context->setOwnerRequestGroup(rg.get());
   
   groups.push_back(rg);
 }
diff --git a/src/BtRegistry.cc b/src/BtRegistry.cc
index 0c90a20c..158da62b 100644
--- a/src/BtRegistry.cc
+++ b/src/BtRegistry.cc
@@ -34,7 +34,7 @@
 /* copyright --> */
 #include "BtRegistry.h"
 #include "DlAbortEx.h"
-#include "BtContext.h"
+#include "DownloadContext.h"
 #include "PeerStorage.h"
 #include "PieceStorage.h"
 #include "BtAnnounce.h"
@@ -43,10 +43,10 @@
 
 namespace aria2 {
 
-SharedHandle<BtContext>
-BtRegistry::getBtContext(const std::string& infoHash) const
+SharedHandle<DownloadContext>
+BtRegistry::getDownloadContext(const std::string& infoHash) const
 {
-  return get(infoHash)._btContext;
+  return get(infoHash)._downloadContext;
 }
 
 void BtRegistry::put(const std::string& infoHash, const BtObject& obj)
diff --git a/src/BtRegistry.h b/src/BtRegistry.h
index bc124b3f..3b3858f8 100644
--- a/src/BtRegistry.h
+++ b/src/BtRegistry.h
@@ -49,23 +49,23 @@ class PieceStorage;
 class BtAnnounce;
 class BtRuntime;
 class BtProgressInfoFile;
-class BtContext;
+class DownloadContext;
 
 struct BtObject {
-  SharedHandle<BtContext> _btContext;
+  SharedHandle<DownloadContext> _downloadContext;
   SharedHandle<PieceStorage> _pieceStorage;
   SharedHandle<PeerStorage> _peerStorage;
   SharedHandle<BtAnnounce> _btAnnounce;
   SharedHandle<BtRuntime> _btRuntime;
   SharedHandle<BtProgressInfoFile> _btProgressInfoFile;
 
-  BtObject(const SharedHandle<BtContext>& btContext,
+  BtObject(const SharedHandle<DownloadContext>& downloadContext,
 	   const SharedHandle<PieceStorage>& pieceStorage,
 	   const SharedHandle<PeerStorage>& peerStorage,
 	   const SharedHandle<BtAnnounce>& btAnnounce,
 	   const SharedHandle<BtRuntime>& btRuntime,
 	   const SharedHandle<BtProgressInfoFile>& btProgressInfoFile):
-    _btContext(btContext),
+    _downloadContext(downloadContext),
     _pieceStorage(pieceStorage),
     _peerStorage(peerStorage),
     _btAnnounce(btAnnounce),
@@ -76,7 +76,7 @@ struct BtObject {
 
   bool isNull() const
   {
-    return _btContext.isNull() &&
+    return _downloadContext.isNull() &&
       _pieceStorage.isNull() &&
       _peerStorage.isNull() &&
       _btAnnounce.isNull() &&
@@ -89,19 +89,21 @@ class BtRegistry {
 private:
   std::map<std::string, BtObject> _pool;
 public:
-  SharedHandle<BtContext> getBtContext(const std::string& infoHash) const;
+  SharedHandle<DownloadContext>
+  getDownloadContext(const std::string& infoHash) const;
 
   void put(const std::string& infoHash, const BtObject& obj);
 
   BtObject get(const std::string& infoHash) const;
 
   template<typename OutputIterator>
-  void getAllBtContext(OutputIterator dest)
+  OutputIterator getAllDownloadContext(OutputIterator dest)
   {
     for(std::map<std::string, BtObject>::const_iterator i = _pool.begin();
 	i != _pool.end(); ++i) {
-      *dest++ = (*i).second._btContext;
+      *dest++ = (*i).second._downloadContext;
     }
+    return dest;
   }
 
   void removeAll();
diff --git a/src/BtSetup.cc b/src/BtSetup.cc
index 26472d98..ea339780 100644
--- a/src/BtSetup.cc
+++ b/src/BtSetup.cc
@@ -58,6 +58,7 @@
 #include "BtProgressInfoFile.h"
 #include "BtAnnounce.h"
 #include "BtRuntime.h"
+#include "bittorrent_helper.h"
 
 namespace aria2 {
 
@@ -68,11 +69,13 @@ void BtSetup::setup(std::deque<Command*>& commands,
 		    DownloadEngine* e,
 		    const Option* option)
 {
-  BtContextHandle btContext(dynamic_pointer_cast<BtContext>(requestGroup->getDownloadContext()));
-  if(btContext.isNull()) {
+  if(!requestGroup->getDownloadContext()->hasAttribute(bittorrent::BITTORRENT)) {
     return;
   }
-  BtObject btObject = e->getBtRegistry()->get(btContext->getInfoHashAsString());
+  const BDE& torrentAttrs =
+    requestGroup->getDownloadContext()->getAttribute(bittorrent::BITTORRENT);
+  BtObject btObject =
+    e->getBtRegistry()->get(torrentAttrs[bittorrent::INFO_HASH].s());
   SharedHandle<PieceStorage> pieceStorage = btObject._pieceStorage;
   SharedHandle<PeerStorage> peerStorage = btObject._peerStorage;
   SharedHandle<BtRuntime> btRuntime = btObject._btRuntime;
@@ -80,7 +83,7 @@ void BtSetup::setup(std::deque<Command*>& commands,
   // commands
   {
     TrackerWatcherCommand* c =
-      new TrackerWatcherCommand(e->newCUID(), requestGroup, e, btContext);
+      new TrackerWatcherCommand(e->newCUID(), requestGroup, e);
     c->setPeerStorage(peerStorage);
     c->setPieceStorage(pieceStorage);
     c->setBtRuntime(btRuntime);
@@ -90,7 +93,7 @@ void BtSetup::setup(std::deque<Command*>& commands,
   }
   {
     PeerChokeCommand* c =
-      new PeerChokeCommand(e->newCUID(), e, btContext);
+      new PeerChokeCommand(e->newCUID(), e);
     c->setPeerStorage(peerStorage);
     c->setBtRuntime(btRuntime);
 
@@ -98,8 +101,7 @@ void BtSetup::setup(std::deque<Command*>& commands,
   }
   {
     ActivePeerConnectionCommand* c =
-      new ActivePeerConnectionCommand(e->newCUID(), requestGroup, e, btContext,
-				      10);
+      new ActivePeerConnectionCommand(e->newCUID(), requestGroup, e, 10);
     c->setBtRuntime(btRuntime);
     c->setPieceStorage(pieceStorage);
     c->setPeerStorage(peerStorage);
@@ -108,11 +110,11 @@ void BtSetup::setup(std::deque<Command*>& commands,
     commands.push_back(c);
   }
 
-  if(!btContext->isPrivate() && DHTSetup::initialized()) {
-    DHTRegistry::_peerAnnounceStorage->addPeerAnnounce(btContext->getInfoHash(),
-						       peerStorage);
+  if(torrentAttrs[bittorrent::PRIVATE].i() == 0 && DHTSetup::initialized()) {
+    DHTRegistry::_peerAnnounceStorage->addPeerAnnounce
+      (torrentAttrs[bittorrent::INFO_HASH].uc(), peerStorage);
     DHTGetPeersCommand* command =
-      new DHTGetPeersCommand(e->newCUID(), requestGroup, e, btContext);
+      new DHTGetPeersCommand(e->newCUID(), requestGroup, e);
     command->setTaskQueue(DHTRegistry::_taskQueue);
     command->setTaskFactory(DHTRegistry::_taskFactory);
     command->setBtRuntime(btRuntime);
@@ -129,7 +131,7 @@ void BtSetup::setup(std::deque<Command*>& commands,
     if(ratio > 0.0) {
       SharedHandle<ShareRatioSeedCriteria> cri
 	(new ShareRatioSeedCriteria(option->getAsDouble(PREF_SEED_RATIO),
-				    btContext));
+				    requestGroup->getDownloadContext()));
       cri->setPieceStorage(pieceStorage);
       cri->setPeerStorage(peerStorage);
 
@@ -138,7 +140,7 @@ void BtSetup::setup(std::deque<Command*>& commands,
   }
   if(unionCri->getSeedCriterion().size() > 0) {
     SeedCheckCommand* c =
-      new SeedCheckCommand(e->newCUID(), requestGroup, e, btContext, unionCri);
+      new SeedCheckCommand(e->newCUID(), requestGroup, e, unionCri);
     c->setPieceStorage(pieceStorage);
     c->setBtRuntime(btRuntime);
     commands.push_back(c);
diff --git a/src/CheckIntegrityCommand.cc b/src/CheckIntegrityCommand.cc
index 4c2858e1..d7b92a2e 100644
--- a/src/CheckIntegrityCommand.cc
+++ b/src/CheckIntegrityCommand.cc
@@ -39,6 +39,7 @@
 #include "Logger.h"
 #include "message.h"
 #include "prefs.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
@@ -62,13 +63,13 @@ bool CheckIntegrityCommand::executeInternal()
 
     if(_requestGroup->downloadFinished()) {
       logger->notice(MSG_VERIFICATION_SUCCESSFUL,
-		     _requestGroup->getFilePath().c_str());
+		     _requestGroup->getDownloadContext()->getBasePath().c_str());
       std::deque<Command*> commands;
       _entry->onDownloadFinished(commands, _e);
       _e->addCommand(commands);
     } else {
       logger->error(MSG_VERIFICATION_FAILED,
-		    _requestGroup->getFilePath().c_str());
+		    _requestGroup->getDownloadContext()->getBasePath().c_str());
       std::deque<Command*> commands;
       _entry->onDownloadIncomplete(commands,_e);
       _e->addCommand(commands);
@@ -86,7 +87,7 @@ bool CheckIntegrityCommand::handleException(Exception& e)
   _e->_checkIntegrityMan->dropPickedEntry();
   logger->error(MSG_FILE_VALIDATION_FAILURE, e, cuid);
   logger->error(MSG_DOWNLOAD_NOT_COMPLETE,
-		cuid, _requestGroup->getFilePath().c_str());
+		cuid, _requestGroup->getDownloadContext()->getBasePath().c_str());
   return true;
 }
 
diff --git a/src/CheckIntegrityEntry.cc b/src/CheckIntegrityEntry.cc
index 85b493b9..2d2eb569 100644
--- a/src/CheckIntegrityEntry.cc
+++ b/src/CheckIntegrityEntry.cc
@@ -41,6 +41,7 @@
 #include "FileAllocationEntry.h"
 #include "DownloadEngine.h"
 #include "Option.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/ChecksumCheckIntegrityEntry.cc b/src/ChecksumCheckIntegrityEntry.cc
index a7e62a1f..7a0897fa 100644
--- a/src/ChecksumCheckIntegrityEntry.cc
+++ b/src/ChecksumCheckIntegrityEntry.cc
@@ -34,7 +34,7 @@
 /* copyright --> */
 #include "ChecksumCheckIntegrityEntry.h"
 #include "RequestGroup.h"
-#include "SingleFileDownloadContext.h"
+#include "DownloadContext.h"
 #include "FileEntry.h"
 #include "IteratableChecksumValidator.h"
 #include "DownloadEngine.h"
@@ -49,18 +49,15 @@ ChecksumCheckIntegrityEntry::~ChecksumCheckIntegrityEntry() {}
 
 bool ChecksumCheckIntegrityEntry::isValidationReady()
 {
-  SingleFileDownloadContextHandle dctx
-    (dynamic_pointer_cast<SingleFileDownloadContext>(_requestGroup->getDownloadContext()));
-  return !dctx.isNull() && dctx->getChecksum().size() > 0 &&
-    dctx->getChecksumHashAlgo().size() > 0;
+  return !_requestGroup->getDownloadContext()->getChecksum().empty() &&
+    !_requestGroup->getDownloadContext()->getChecksumHashAlgo().empty();
 }
 
 void ChecksumCheckIntegrityEntry::initValidator()
 {
-  SingleFileDownloadContextHandle dctx
-    (dynamic_pointer_cast<SingleFileDownloadContext>(_requestGroup->getDownloadContext()));
-  _validator.reset(new IteratableChecksumValidator(dctx,
-						   _requestGroup->getPieceStorage()));
+  _validator.reset(new IteratableChecksumValidator
+		   (_requestGroup->getDownloadContext(),
+		    _requestGroup->getPieceStorage()));
   _validator->init();
 }
 
diff --git a/src/ConsoleStatCalc.cc b/src/ConsoleStatCalc.cc
index c6c94631..8add12b6 100644
--- a/src/ConsoleStatCalc.cc
+++ b/src/ConsoleStatCalc.cc
@@ -57,8 +57,9 @@
 #include "CheckIntegrityMan.h"
 #include "CheckIntegrityEntry.h"
 #include "Util.h"
+#include "DownloadContext.h"
 #ifdef ENABLE_BITTORRENT
-# include "BtContext.h"
+# include "bittorrent_helper.h"
 # include "Peer.h"
 # include "PeerStorage.h"
 # include "BtRegistry.h"
@@ -83,10 +84,8 @@ static void printProgress
     << "#" << rg->getGID() << " ";
 
 #ifdef ENABLE_BITTORRENT
-  SharedHandle<BtContext> btctx =
-    dynamic_pointer_cast<BtContext>(rg->getDownloadContext());
-
-  if(!btctx.isNull() && rg->downloadFinished()) {
+  if(rg->getDownloadContext()->hasAttribute(bittorrent::BITTORRENT) &&
+     rg->downloadFinished()) {
     o << "SEEDING" << "(" << "ratio:";
     if(rg->getCompletedLength() > 0) {
       o << std::fixed << std::setprecision(1)
@@ -114,9 +113,11 @@ static void printProgress
     << "CN:"
     << rg->getNumConnection();
 #ifdef ENABLE_BITTORRENT
-  if(!btctx.isNull()) {
+  if(rg->getDownloadContext()->hasAttribute(bittorrent::BITTORRENT)) {
+    const BDE& torrentAttrs =
+      rg->getDownloadContext()->getAttribute(bittorrent::BITTORRENT);
     SharedHandle<PeerStorage> ps =
-      e->getBtRegistry()->get(btctx->getInfoHashAsString())._peerStorage;
+      e->getBtRegistry()->get(torrentAttrs[bittorrent::INFO_HASH].s())._peerStorage;
     std::deque<SharedHandle<Peer> > peers;
     ps->getActivePeers(peers);
     o << " " << "SEED:"
@@ -155,7 +156,7 @@ public:
   {
     const char SEP_CHAR = '-';
     printProgress(std::cout, rg, _e);
-    const std::deque<SharedHandle<FileEntry> >& fileEntries =
+    const std::vector<SharedHandle<FileEntry> >& fileEntries =
       rg->getDownloadContext()->getFileEntries();
     std::cout << "\n"
 	      << "FILE: ";
diff --git a/src/ContentTypeRequestGroupCriteria.cc b/src/ContentTypeRequestGroupCriteria.cc
index cd06ab4b..d479bc88 100644
--- a/src/ContentTypeRequestGroupCriteria.cc
+++ b/src/ContentTypeRequestGroupCriteria.cc
@@ -34,9 +34,9 @@
 /* copyright --> */
 #include "ContentTypeRequestGroupCriteria.h"
 #include "RequestGroup.h"
-#include "SingleFileDownloadContext.h"
 #include "Util.h"
 #include "FileEntry.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
@@ -49,15 +49,15 @@ ContentTypeRequestGroupCriteria::~ContentTypeRequestGroupCriteria() {}
 
 bool ContentTypeRequestGroupCriteria::match(const RequestGroup* requestGroup) const
 {
-  if(forwardMatch(requestGroup->getFilePath(), _extensions)) {
+  if(requestGroup->getDownloadContext()->getFileEntries().size() != 1) {
+    return false;
+  }
+  if(forwardMatch(requestGroup->getFirstFilePath(), _extensions)) {
     return true;
   } else {
-    SingleFileDownloadContextHandle dctx(dynamic_pointer_cast<SingleFileDownloadContext>(requestGroup->getDownloadContext()));
-    if(dctx.isNull()) {
-      return false;
-    } else {
-      return exactMatch(dctx->getContentType(), _contentTypes);
-    }
+    return exactMatch
+      (requestGroup->getDownloadContext()->getFirstFileEntry()->getContentType(),
+       _contentTypes);
   }
 }
 
diff --git a/src/DHTGetPeersCommand.cc b/src/DHTGetPeersCommand.cc
index 594ff8ff..ee65dd84 100644
--- a/src/DHTGetPeersCommand.cc
+++ b/src/DHTGetPeersCommand.cc
@@ -40,21 +40,20 @@
 #include "RequestGroup.h"
 #include "DHTNode.h"
 #include "DHTNodeLookupEntry.h"
-#include "BtContext.h"
 #include "BtRuntime.h"
 #include "PeerStorage.h"
 #include "Peer.h"
 #include "Logger.h"
+#include "bittorrent_helper.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
 DHTGetPeersCommand::DHTGetPeersCommand(int32_t cuid,
 				       RequestGroup* requestGroup,
-				       DownloadEngine* e,
-				       const BtContextHandle& ctx):
+				       DownloadEngine* e):
   Command(cuid),
   _requestGroup(requestGroup),
-  _btContext(ctx),
   _e(e),
   _numRetry(0),
   _lastGetPeerTime(0)
@@ -76,9 +75,9 @@ bool DHTGetPeersCommand::execute()
      ((_numRetry > 0 && _lastGetPeerTime.elapsed(RETRY_INTERVAL)) ||
       _lastGetPeerTime.elapsed(GET_PEER_INTERVAL))) {
     logger->debug("Issuing PeerLookup for infoHash=%s",
-		  _btContext->getInfoHashAsString().c_str());
-    _task = _taskFactory->createPeerLookupTask(_btContext, _btRuntime,
-					       _peerStorage);
+		  bittorrent::getInfoHashString(_requestGroup->getDownloadContext()).c_str());
+    _task = _taskFactory->createPeerLookupTask
+      (_requestGroup->getDownloadContext(), _btRuntime, _peerStorage);
     _taskQueue->addPeriodicTask2(_task);
   } else if(!_task.isNull() && _task->finished()) {
     _lastGetPeerTime.reset();
diff --git a/src/DHTGetPeersCommand.h b/src/DHTGetPeersCommand.h
index f29bbc8e..dee0e21a 100644
--- a/src/DHTGetPeersCommand.h
+++ b/src/DHTGetPeersCommand.h
@@ -47,7 +47,6 @@ class DHTTaskFactory;
 class DHTTask;
 class DownloadEngine;
 class RequestGroup;
-class BtContext;
 class BtRuntime;
 class PeerStorage;
 
@@ -61,8 +60,6 @@ private:
 
   RequestGroup* _requestGroup;
 
-  SharedHandle<BtContext> _btContext;
-
   SharedHandle<BtRuntime> _btRuntime;
 
   SharedHandle<PeerStorage> _peerStorage;
@@ -80,8 +77,7 @@ private:
   Time _lastGetPeerTime;
 public:
   DHTGetPeersCommand(int32_t cuid, RequestGroup* requestGroup,
-		     DownloadEngine* e,
-		     const SharedHandle<BtContext>& ctx);
+		     DownloadEngine* e);
 
   virtual ~DHTGetPeersCommand();
 
diff --git a/src/DHTPeerLookupTask.cc b/src/DHTPeerLookupTask.cc
index 6869498a..6d4a0a9c 100644
--- a/src/DHTPeerLookupTask.cc
+++ b/src/DHTPeerLookupTask.cc
@@ -43,15 +43,15 @@
 #include "DHTMessageCallback.h"
 #include "PeerStorage.h"
 #include "BtRuntime.h"
-#include "BtContext.h"
 #include "Util.h"
 #include "DHTBucket.h"
+#include "bittorrent_helper.h"
 
 namespace aria2 {
 
-DHTPeerLookupTask::DHTPeerLookupTask(const SharedHandle<BtContext>& btContext):
-  DHTAbstractNodeLookupTask(btContext->getInfoHash()),
-  _ctx(btContext) {}
+DHTPeerLookupTask::DHTPeerLookupTask
+(const SharedHandle<DownloadContext>& downloadContext):
+  DHTAbstractNodeLookupTask(bittorrent::getInfoHash(downloadContext)) {}
 
 void
 DHTPeerLookupTask::getNodesFromMessage(std::deque<SharedHandle<DHTNode> >& nodes,
@@ -92,11 +92,11 @@ void DHTPeerLookupTask::onFinish()
     if((*i)->_used) {
       const SharedHandle<DHTNode>& node = (*i)->_node;
       SharedHandle<DHTMessage> m = 
-	_factory->createAnnouncePeerMessage(node,
-					    _ctx->getInfoHash(),
-					    _btRuntime->getListenPort(),
-					    _tokenStorage[Util::toHex(node->getID(),
-								      DHT_ID_LENGTH)]);
+	_factory->createAnnouncePeerMessage
+	(node,
+	 _targetID, // this is infoHash
+	 _btRuntime->getListenPort(),
+	 _tokenStorage[Util::toHex(node->getID(), DHT_ID_LENGTH)]);
       _dispatcher->addMessageToQueue(m);
     }
   }
diff --git a/src/DHTPeerLookupTask.h b/src/DHTPeerLookupTask.h
index 261e61c3..d448f74a 100644
--- a/src/DHTPeerLookupTask.h
+++ b/src/DHTPeerLookupTask.h
@@ -40,7 +40,7 @@
 
 namespace aria2 {
 
-class BtContext;
+class DownloadContext;
 class Peer;
 class PeerStorage;
 class BtRuntime;
@@ -51,13 +51,11 @@ private:
 
   std::deque<SharedHandle<Peer> > _peers;
 
-  SharedHandle<BtContext> _ctx;
-
   SharedHandle<PeerStorage> _peerStorage;
 
   SharedHandle<BtRuntime> _btRuntime;
 public:
-  DHTPeerLookupTask(const SharedHandle<BtContext>& btContext);
+  DHTPeerLookupTask(const SharedHandle<DownloadContext>& downloadContext);
 
   virtual void getNodesFromMessage(std::deque<SharedHandle<DHTNode> >& nodes,
 				   const SharedHandle<DHTMessage>& message);
diff --git a/src/DHTTaskFactory.h b/src/DHTTaskFactory.h
index b5c8dcf9..91988e1a 100644
--- a/src/DHTTaskFactory.h
+++ b/src/DHTTaskFactory.h
@@ -40,7 +40,7 @@
 
 namespace aria2 {
 
-class BtContext;
+class DownloadContext;
 class BtRuntime;
 class PeerStorage;
 class DHTTask;
@@ -61,7 +61,7 @@ public:
   virtual SharedHandle<DHTTask> createBucketRefreshTask() = 0;
 
   virtual SharedHandle<DHTTask>
-  createPeerLookupTask(const SharedHandle<BtContext>& ctx,
+  createPeerLookupTask(const SharedHandle<DownloadContext>& ctx,
 		       const SharedHandle<BtRuntime>& btRuntime,
 		       const SharedHandle<PeerStorage>& peerStorage) = 0;
   
diff --git a/src/DHTTaskFactoryImpl.cc b/src/DHTTaskFactoryImpl.cc
index d4e93725..6d794b88 100644
--- a/src/DHTTaskFactoryImpl.cc
+++ b/src/DHTTaskFactoryImpl.cc
@@ -47,7 +47,6 @@
 #include "DHTReplaceNodeTask.h"
 #include "Peer.h"
 #include "DHTNodeLookupEntry.h"
-#include "BtContext.h"
 #include "PeerStorage.h"
 #include "BtRuntime.h"
 #include "DHTMessageCallback.h"
@@ -85,7 +84,7 @@ DHTTaskFactoryImpl::createBucketRefreshTask()
 
 SharedHandle<DHTTask>
 DHTTaskFactoryImpl::createPeerLookupTask
-(const SharedHandle<BtContext>& ctx,
+(const SharedHandle<DownloadContext>& ctx,
  const SharedHandle<BtRuntime>& btRuntime,
  const SharedHandle<PeerStorage>& peerStorage)
 {
diff --git a/src/DHTTaskFactoryImpl.h b/src/DHTTaskFactoryImpl.h
index 9d8c1649..e6f2e5b2 100644
--- a/src/DHTTaskFactoryImpl.h
+++ b/src/DHTTaskFactoryImpl.h
@@ -77,7 +77,7 @@ public:
   virtual SharedHandle<DHTTask> createBucketRefreshTask();
 
   virtual SharedHandle<DHTTask>
-  createPeerLookupTask(const SharedHandle<BtContext>& ctx,
+  createPeerLookupTask(const SharedHandle<DownloadContext>& ctx,
 		       const SharedHandle<BtRuntime>& btRuntime,
 		       const SharedHandle<PeerStorage>& peerStorage);
 
diff --git a/src/DefaultBtAnnounce.cc b/src/DefaultBtAnnounce.cc
index 377b0ae3..3cdeb360 100644
--- a/src/DefaultBtAnnounce.cc
+++ b/src/DefaultBtAnnounce.cc
@@ -41,7 +41,7 @@
 #include "DlAbortEx.h"
 #include "message.h"
 #include "SimpleRandomizer.h"
-#include "BtContext.h"
+#include "DownloadContext.h"
 #include "PieceStorage.h"
 #include "BtRuntime.h"
 #include "PeerStorage.h"
@@ -51,19 +51,21 @@
 #include "A2STR.h"
 #include "Request.h"
 #include "bencode.h"
+#include "bittorrent_helper.h"
 
 namespace aria2 {
 
-DefaultBtAnnounce::DefaultBtAnnounce(const BtContextHandle& btContext,
-				     const Option* option):
-  btContext(btContext),
+DefaultBtAnnounce::DefaultBtAnnounce
+(const SharedHandle<DownloadContext>& downloadContext,
+ const Option* option):
+  _downloadContext(downloadContext),
   trackers(0),
   interval(DEFAULT_ANNOUNCE_INTERVAL),
   minInterval(DEFAULT_ANNOUNCE_INTERVAL),
   _userDefinedInterval(0),
   complete(0),
   incomplete(0),
-  announceList(btContext->getAnnounceTiers()),
+  announceList(downloadContext->getAttribute(bittorrent::BITTORRENT)[bittorrent::ANNOUNCE_LIST]),
   option(option),
   logger(LogFactory::getInstance()),
   _randomizer(SimpleRandomizer::getInstance())
@@ -145,10 +147,10 @@ std::string DefaultBtAnnounce::getAnnounceUrl() {
   std::string url = announceList.getAnnounce();
   url += uriHasQuery(url) ? "&" : "?";
   url += "info_hash=";
-  url += Util::torrentUrlencode(btContext->getInfoHash(),
-				btContext->getInfoHashLength());
+  url += Util::torrentUrlencode(bittorrent::getInfoHash(_downloadContext),
+				INFO_HASH_LENGTH);
   url += "&peer_id=";
-  url += Util::torrentUrlencode(btContext->getPeerId(), 20);
+  url += Util::torrentUrlencode(bittorrent::getStaticPeerId(), PEER_ID_LENGTH);
   url += "&uploaded=";
   url += Util::uitos(stat.getSessionUploadLength());
   url += "&downloaded=";
diff --git a/src/DefaultBtAnnounce.h b/src/DefaultBtAnnounce.h
index a561bbec..812cb3e8 100644
--- a/src/DefaultBtAnnounce.h
+++ b/src/DefaultBtAnnounce.h
@@ -41,7 +41,7 @@
 
 namespace aria2 {
 
-class BtContext;
+class DownloadContext;
 class Option;
 class Logger;
 class BtRuntime;
@@ -51,7 +51,7 @@ class Randomizer;
 
 class DefaultBtAnnounce : public BtAnnounce {
 private:
-  SharedHandle<BtContext> btContext;
+  SharedHandle<DownloadContext> _downloadContext;
   unsigned int trackers;
   Time prevAnnounceTime;
   time_t interval;
@@ -69,7 +69,7 @@ private:
   SharedHandle<PieceStorage> pieceStorage;
   SharedHandle<PeerStorage> peerStorage;
 public:
-  DefaultBtAnnounce(const SharedHandle<BtContext>& btContext,
+  DefaultBtAnnounce(const SharedHandle<DownloadContext>& downloadContext,
 		    const Option* option);
 
   virtual ~DefaultBtAnnounce();
diff --git a/src/DefaultBtContext.cc b/src/DefaultBtContext.cc
deleted file mode 100644
index 29aaea47..00000000
--- a/src/DefaultBtContext.cc
+++ /dev/null
@@ -1,577 +0,0 @@
-/* <!-- copyright */
-/*
- * aria2 - The high speed download utility
- *
- * Copyright (C) 2006 Tatsuhiro Tsujikawa
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- *
- * In addition, as a special exception, the copyright holders give
- * permission to link the code of portions of this program with the
- * OpenSSL library under certain conditions as described in each
- * individual source file, and distribute linked combinations
- * including the two.
- * You must obey the GNU General Public License in all respects
- * for all of the code used other than OpenSSL.  If you modify
- * file(s) with this exception, you may extend this exception to your
- * version of the file(s), but you are not obligated to do so.  If you
- * do not wish to do so, delete this exception statement from your
- * version.  If you delete this exception statement from all source
- * files in the program, then also delete it here.
- */
-/* copyright --> */
-#include "DefaultBtContext.h"
-
-#include <cstring>
-#include <ostream>
-#include <functional>
-#include <algorithm>
-#include <vector>
-
-#include "DlAbortEx.h"
-#include "Util.h"
-#include "MessageDigestHelper.h"
-#include "a2netcompat.h"
-#include "AnnounceTier.h"
-#include "SimpleRandomizer.h"
-#include "LogFactory.h"
-#include "Logger.h"
-#include "FileEntry.h"
-#include "message.h"
-#include "PeerMessageUtil.h"
-#include "StringFormat.h"
-#include "A2STR.h"
-#include "bencode.h"
-#include "a2functional.h"
-
-namespace aria2 {
-
-const std::string DefaultBtContext::C_NAME("name");
-
-const std::string DefaultBtContext::C_NAME_UTF8("name.utf-8");
-
-const std::string DefaultBtContext::C_FILES("files");
-
-const std::string DefaultBtContext::C_LENGTH("length");
-
-const std::string DefaultBtContext::C_PATH("path");
-
-const std::string DefaultBtContext::C_PATH_UTF8("path.utf-8");
-
-const std::string DefaultBtContext::C_INFO("info");
-
-const std::string DefaultBtContext::C_PIECES("pieces");
-
-const std::string DefaultBtContext::C_PIECE_LENGTH("piece length");
-
-const std::string DefaultBtContext::C_PRIVATE("private");
-
-const std::string DefaultBtContext::C_PRIVATE_ON("1");
-
-const std::string DefaultBtContext::C_URL_LIST("url-list");
-
-const std::string DefaultBtContext::C_ANNOUNCE("announce");
-
-const std::string DefaultBtContext::C_ANNOUNCE_LIST("announce-list");
-
-const std::string DefaultBtContext::C_NODES("nodes");
-
-const std::string DefaultBtContext::DEFAULT_PEER_ID_PREFIX("-aria2-");
-
-DefaultBtContext::DefaultBtContext():_peerIdPrefix(DEFAULT_PEER_ID_PREFIX),
-				     _randomizer(SimpleRandomizer::getInstance()),
-				     _ownerRequestGroup(0),
-				     _logger(LogFactory::getInstance()) {}
-
-DefaultBtContext::~DefaultBtContext() {}
-
-std::string DefaultBtContext::generatePeerId() const {
-  std::string peerId = _peerIdPrefix;
-  peerId += Util::randomAlpha(20-_peerIdPrefix.size(), _randomizer);
-  if(peerId.size() > 20) {
-    peerId.erase(20);
-  }
-  return peerId;
-}
-
-const unsigned char* DefaultBtContext::getInfoHash() const {
-  return infoHash;
-}
-
-size_t DefaultBtContext::getInfoHashLength() const {
-  return INFO_HASH_LENGTH;
-}
-
-const std::string& DefaultBtContext::getInfoHashAsString() const {
-  return infoHashString;
-}
-
-void DefaultBtContext::clear() {
-  memset(infoHash, 0, INFO_HASH_LENGTH);
-  infoHashString = A2STR::NIL;
-  pieceHashes.clear();
-  _fileEntries.clear();
-  totalLength = 0;
-  pieceLength = 0;
-  fileMode = BtContext::SINGLE;
-  numPieces = 0;
-  name = A2STR::NIL;
-  announceTiers.clear();
-  _private = false;
-}
-
-void DefaultBtContext::extractPieceHash(const std::string& hashData,
-					size_t hashLength)
-{
-  size_t numPieces = hashData.size()/hashLength;
-  for(size_t i = 0; i < numPieces; ++i) {
-    pieceHashes.push_back(Util::toHex(hashData.data()+i*hashLength,
-				      hashLength));
-  }
-}
-
-void DefaultBtContext::extractFileEntries(const BDE& infoDict,
-					  const std::string& defaultName,
-					  const std::string& overrideName,
-					  const std::deque<std::string>& urlList)
-{
-  if(overrideName.empty()) {
-    std::string nameKey;
-    if(infoDict.containsKey(C_NAME_UTF8)) {
-      nameKey = C_NAME_UTF8;
-    } else {
-      nameKey = C_NAME;
-    }
-    const BDE& nameData = infoDict[nameKey];
-    if(nameData.isString()) {
-      name = nameData.s();
-    } else {
-      name = strconcat(File(defaultName).getBasename(), ".file");
-    }
-  } else {
-    name = overrideName;
-  }
-  const BDE& filesList = infoDict[C_FILES];
-  if(filesList.isList()) {
-    uint64_t length = 0;
-    off_t offset = 0;
-    // multi-file mode
-    fileMode = BtContext::MULTI;
-    for(BDE::List::const_iterator itr = filesList.listBegin();
-	itr != filesList.listEnd(); ++itr) {
-      const BDE& fileDict = *itr;
-      if(!fileDict.isDict()) {
-	continue;
-      }
-
-      const BDE& fileLengthData = fileDict[C_LENGTH];
-      if(!fileLengthData.isInteger()) {
-	throw DL_ABORT_EX(StringFormat(MSG_MISSING_BT_INFO,
-				       C_LENGTH.c_str()).str());
-      }
-      length += fileLengthData.i();
-
-      std::string pathKey;
-      if(fileDict.containsKey(C_PATH_UTF8)) {
-	pathKey = C_PATH_UTF8;
-      } else {
-	pathKey = C_PATH;
-      }
-      const BDE& pathList = fileDict[pathKey];
-      if(!pathList.isList() || pathList.empty()) {
-	throw DL_ABORT_EX("Path is empty.");
-      }
-      
-      std::vector<std::string> pathelem(pathList.size());
-      std::transform(pathList.listBegin(), pathList.listEnd(), pathelem.begin(),
-		     std::mem_fun_ref(&BDE::s));
-      std::string path = name;
-      strappend(path, "/", Util::joinPath(pathelem.begin(), pathelem.end()));
-      // Split path with '/' again because each pathList element can
-      // contain "/" inside.
-      std::deque<std::string> elements;
-      Util::slice(elements, path, '/');
-      path = Util::joinPath(elements.begin(), elements.end());
-
-      std::deque<std::string> uris;
-      std::transform(urlList.begin(), urlList.end(), std::back_inserter(uris),
-		     std::bind2nd(std::plus<std::string>(), "/"+path));
-      FileEntryHandle fileEntry(new FileEntry(strconcat(_dir, "/", path),
-					      fileLengthData.i(),
-					      offset, uris));
-      _fileEntries.push_back(fileEntry);
-      offset += fileEntry->getLength();
-    }
-    totalLength = length;
-  } else {
-    // single-file mode;
-    fileMode = BtContext::SINGLE;
-    const BDE& lengthData = infoDict[C_LENGTH];
-    if(!lengthData.isInteger()) {
-	throw DL_ABORT_EX(StringFormat(MSG_MISSING_BT_INFO,
-				       C_LENGTH.c_str()).str());      
-    }
-    totalLength = lengthData.i();
-    // Slice path by '/' just in case nasty ".." is included in name
-    std::deque<std::string> pathelems;
-    Util::slice(pathelems, name, '/');
-
-    // For each uri in urlList, if it ends with '/', then
-    // concatenate name to it. Specification just says so.
-    std::deque<std::string> uris;
-    for(std::deque<std::string>::const_iterator i = urlList.begin();
-	i != urlList.end(); ++i) {
-      if(Util::endsWith(*i, "/")) {
-	uris.push_back((*i)+name);
-      } else {
-	uris.push_back(*i);
-      }
-    }
-
-    SharedHandle<FileEntry> fileEntry
-      (new FileEntry(strconcat(_dir, "/",
-			       Util::joinPath(pathelems.begin(),
-					      pathelems.end())),
-		     totalLength, 0, uris));
-    _fileEntries.push_back(fileEntry);
-  }
-}
-
-void DefaultBtContext::extractAnnounceURI(const BDE& announceData)
-{
-  // Assumed announceData is string
-  std::deque<std::string> urls;
-  urls.push_back(Util::trim(announceData.s()));
-  announceTiers.push_back(AnnounceTierHandle(new AnnounceTier(urls)));
-}
-
-void DefaultBtContext::extractAnnounceList(const BDE& announceList)
-{
-  // Assumed announceList is string
-  for(BDE::List::const_iterator itr = announceList.listBegin();
-      itr != announceList.listEnd(); ++itr) {
-    const BDE& elemList = *itr;
-    if(!elemList.isList()) {
-      continue;
-    }
-    std::deque<std::string> urls;
-    for(BDE::List::const_iterator elemItr = elemList.listBegin();
-	elemItr != elemList.listEnd(); ++elemItr) {
-      const BDE& url = (*elemItr);
-      if(url.isString()) {
-	urls.push_back(Util::trim(url.s()));
-      }
-    }
-    if(!urls.empty()) {
-      AnnounceTierHandle tier(new AnnounceTier(urls));
-      announceTiers.push_back(tier);
-    }
-  }
-}
-
-void DefaultBtContext::extractAnnounce(const BDE& rootDict)
-{
-  const BDE& announceList = rootDict[C_ANNOUNCE_LIST];
-  if(announceList.isList()) {
-    extractAnnounceList(announceList);
-  } else {
-    const BDE& announce = rootDict[C_ANNOUNCE];
-    if(announce.isString()) {
-      extractAnnounceURI(announce);
-    }
-  }
-}
-
-void DefaultBtContext::extractUrlList(std::deque<std::string>& uris,
-				      const BDE& bde)
-{
-  if(bde.isList()) {
-    for(BDE::List::const_iterator itr = bde.listBegin();
-	itr != bde.listEnd(); ++itr) {
-      if((*itr).isString()) {
-	uris.push_back((*itr).s());
-      }
-    }
-  } else if(bde.isString()) {
-    uris.push_back(bde.s());
-  }
-}
-
-void DefaultBtContext::extractNodes(const BDE& nodesList)
-{
-  if(!nodesList.isList()) {
-    return;
-  }
-  for(BDE::List::const_iterator i = nodesList.listBegin();
-      i != nodesList.listEnd(); ++i) {
-    const BDE& addrPairList = (*i);
-    if(!addrPairList.isList() || addrPairList.size() != 2) {
-      continue;
-    }
-    const BDE& hostname = addrPairList[0];
-    if(!hostname.isString()) {
-      continue;
-    }
-    if(Util::trim(hostname.s()).empty()) {
-      continue;
-    }
-    const BDE& port = addrPairList[1];
-    if(!port.isInteger() || !(0 < port.i() && port.i() < 65536)) {
-      continue;
-    }
-    _nodes.push_back(std::pair<std::string, uint16_t>(hostname.s(), port.i()));
-  }
-}
-
-void DefaultBtContext::loadFromMemory(const unsigned char* content,
-				      size_t length,
-				      const std::string& defaultName,
-				      const std::string& overrideName)
-{
-  processRootDictionary(bencode::decode(content, length), defaultName,
-			overrideName);
-}
-
-void DefaultBtContext::load(const std::string& torrentFile,
-			    const std::string& overrideName) {
-  processRootDictionary(bencode::decodeFromFile(torrentFile), torrentFile,
-			overrideName);
-}
-
-void DefaultBtContext::processRootDictionary(const BDE& rootDict,
-					     const std::string& defaultName,
-					     const std::string& overrideName)
-{
-  clear();
-  if(!rootDict.isDict()) {
-    throw DL_ABORT_EX("torrent file does not contain a root dictionary.");
-  }
-  const BDE& infoDict = rootDict[C_INFO];
-  if(!infoDict.isDict()) {
-    throw DL_ABORT_EX(StringFormat(MSG_MISSING_BT_INFO,
-				   C_INFO.c_str()).str());
-  }
-  // retrieve infoHash
-  std::string encodedInfoDict = bencode::encode(infoDict);
-  MessageDigestHelper::digest(infoHash, INFO_HASH_LENGTH,
-			      MessageDigestContext::SHA1,
-			      encodedInfoDict.data(),
-			      encodedInfoDict.size());
-  infoHashString = Util::toHex(infoHash, INFO_HASH_LENGTH);
-  // calculate the number of pieces
-  const BDE& piecesData = infoDict[C_PIECES];
-  if(!piecesData.isString()) {
-    throw DL_ABORT_EX(StringFormat(MSG_MISSING_BT_INFO,
-				   C_PIECES.c_str()).str());
-  }
-  if(piecesData.s().empty()) {
-    throw DL_ABORT_EX("The length of piece hash is 0.");
-  }
-  numPieces = piecesData.s().size()/PIECE_HASH_LENGTH;
-  if(numPieces == 0) {
-    throw DL_ABORT_EX("The number of pieces is 0.");
-  }
-  // retrieve piece length
-  const BDE& pieceLengthData = infoDict[C_PIECE_LENGTH];
-  if(!pieceLengthData.isInteger()) {
-    throw DL_ABORT_EX(StringFormat(MSG_MISSING_BT_INFO,
-				   C_PIECE_LENGTH.c_str()).str());
-  }
-  pieceLength = pieceLengthData.i();
-  // retrieve piece hashes
-  extractPieceHash(piecesData.s(), PIECE_HASH_LENGTH);
-  // private flag
-  const BDE& privateData = infoDict[C_PRIVATE];
-  if(privateData.isInteger()) {
-    _private = (privateData.i() == 1);
-  }
-  // retrieve uri-list.
-  // This implemantation obeys HTTP-Seeding specification:
-  // see http://www.getright.com/seedtorrent.html
-  std::deque<std::string> urlList;
-  extractUrlList(urlList, rootDict[C_URL_LIST]);
-
-  // retrieve file entries
-  extractFileEntries(infoDict, defaultName, overrideName, urlList);
-  if((totalLength+pieceLength-1)/pieceLength != numPieces) {
-    throw DL_ABORT_EX("Too few/many piece hash.");
-  }
-  // retrieve announce
-  extractAnnounce(rootDict);
-  // retrieve nodes
-  extractNodes(rootDict[C_NODES]);
-}
-
-const std::string& DefaultBtContext::getPieceHash(size_t index) const {
-  if(index < numPieces) {
-    return pieceHashes[index];
-  } else {
-    return A2STR::NIL;
-  }
-}
-
-uint64_t DefaultBtContext::getTotalLength() const {
-  return totalLength;
-}
-
-bool DefaultBtContext::knowsTotalLength() const
-{
-  return true;
-}
-
-BtContext::FILE_MODE DefaultBtContext::getFileMode() const {
-  return fileMode;
-}
-
-const std::string& DefaultBtContext::getPieceHashAlgo() const
-{
-  return MessageDigestContext::SHA1;
-}
-
-const std::deque<SharedHandle<AnnounceTier> >&
-DefaultBtContext::getAnnounceTiers() const
-{
-  return announceTiers;
-}
-
-const std::string& DefaultBtContext::getName() const {
-  return name;
-}
-
-size_t DefaultBtContext::getPieceLength() const {
-  return pieceLength;
-}
-
-size_t DefaultBtContext::getNumPieces() const {
-  return numPieces;
-}
-
-std::string DefaultBtContext::getActualBasePath() const
-{
-  if(_fileEntries.size() == 1) {
-    return _fileEntries.front()->getPath();
-  } else {
-    return strconcat(_dir, "/", name);
-  }
-}
-
-void DefaultBtContext::computeFastSet
-(std::deque<size_t>& fastSet, const std::string& ipaddr, size_t fastSetSize)
-{
-  unsigned char compact[6];
-  if(!PeerMessageUtil::createcompact(compact, ipaddr, 0)) {
-    return;
-  }
-  if(numPieces < fastSetSize) {
-    fastSetSize = numPieces;
-  }
-  unsigned char tx[24];
-  memcpy(tx, compact, 4);
-  if((tx[0] & 0x80) == 0 || (tx[0] & 0x40) == 0) {
-    tx[2] = 0x00;
-    tx[3] = 0x00;
-  } else {
-    tx[3] = 0x00;
-  }
-  memcpy(tx+4, infoHash, 20);
-  unsigned char x[20];
-  MessageDigestHelper::digest(x, sizeof(x), MessageDigestContext::SHA1, tx, 24);
-  while(fastSet.size() < fastSetSize) {
-    for(size_t i = 0; i < 5 && fastSet.size() < fastSetSize; ++i) {
-      size_t j = i*4;
-      uint32_t ny;
-      memcpy(&ny, x+j, 4);
-      uint32_t y = ntohl(ny);
-      size_t index = y%numPieces;
-      if(std::find(fastSet.begin(), fastSet.end(), index) == fastSet.end()) {
-	fastSet.push_back(index);
-      }
-    }
-    unsigned char temp[20];
-    MessageDigestHelper::digest(temp, sizeof(temp), MessageDigestContext::SHA1, x, sizeof(x));
-    memcpy(x, temp, sizeof(x));
-  }
-}
-
-std::ostream& operator<<(std::ostream& o, const DefaultBtContext& ctx)
-{
-  o << "*** BitTorrent File Information ***" << "\n";
-  o << "Mode: " << (ctx.getFileMode() == DownloadContext::SINGLE ? "Single File Torrent":"Multi File Torrent") << "\n";
-  o << "Announce:" << "\n";
-  AnnounceTiers tiers = ctx.getAnnounceTiers();
-  for(AnnounceTiers::const_iterator itr = tiers.begin(); itr != tiers.end(); ++itr) {
-    const AnnounceTierHandle& tier = *itr;
-    for(std::deque<std::string>::const_iterator uriItr = tier->urls.begin(); uriItr != tier->urls.end(); ++uriItr) {
-      o << " " << *uriItr;
-    }
-    o << "\n";
-  }
-  o << "Info Hash: " << ctx.getInfoHashAsString() << "\n";
-  o << "Piece Length: " << Util::abbrevSize(ctx.getPieceLength()) << "B\n";
-  o << "The Number of Pieces: " << ctx.getNumPieces() << "\n";
-  o << "Total Length: " << Util::abbrevSize(ctx.getTotalLength()) << "B\n";
-  if(ctx.getFileMode() == DownloadContext::MULTI) {
-    o << "Name: " << ctx.getName() << "\n";
-  }
-  Util::toStream(o, ctx.getFileEntries());
-  return o;
-}
-
-void DefaultBtContext::setRandomizer(const RandomizerHandle& randomizer)
-{
-  _randomizer = randomizer;
-}
-
-std::deque<std::pair<std::string, uint16_t> >&
-DefaultBtContext::getNodes()
-{
-  return _nodes;
-}
-
-void DefaultBtContext::setInfoHash(const unsigned char* infoHash)
-{
-  memcpy(this->infoHash, infoHash, sizeof(this->infoHash));
-}
-
-void DefaultBtContext::setFilePathWithIndex
-(size_t index, const std::string& path)
-{
-  if(0 < index && index <= _fileEntries.size()) {
-    _fileEntries[index-1]->setPath(path);
-  } else {
-    throw DL_ABORT_EX(StringFormat("No such file with index=%u",
-				 static_cast<unsigned int>(index)).str());
-  }
-}
-
-void DefaultBtContext::setFileFilter(IntSequence seq)
-{
-  std::deque<int32_t> fileIndexes = seq.flush();
-  std::sort(fileIndexes.begin(), fileIndexes.end());
-  fileIndexes.erase(std::unique(fileIndexes.begin(), fileIndexes.end()),
-		    fileIndexes.end());
-
-  bool selectAll = fileIndexes.empty() || _fileEntries.size() == 1;
-    
-  int32_t index = 1;
-  for(std::deque<SharedHandle<FileEntry> >::const_iterator i =
-	_fileEntries.begin(); i != _fileEntries.end(); ++i, ++index) {
-    (*i)->setRequested
-      (selectAll ||
-       std::binary_search(fileIndexes.begin(), fileIndexes.end(), index));
-  }
-}
-
-} // namespace aria2
diff --git a/src/DefaultBtContext.h b/src/DefaultBtContext.h
deleted file mode 100644
index a238c7a8..00000000
--- a/src/DefaultBtContext.h
+++ /dev/null
@@ -1,232 +0,0 @@
-/* <!-- copyright */
-/*
- * aria2 - The high speed download utility
- *
- * Copyright (C) 2006 Tatsuhiro Tsujikawa
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- *
- * In addition, as a special exception, the copyright holders give
- * permission to link the code of portions of this program with the
- * OpenSSL library under certain conditions as described in each
- * individual source file, and distribute linked combinations
- * including the two.
- * You must obey the GNU General Public License in all respects
- * for all of the code used other than OpenSSL.  If you modify
- * file(s) with this exception, you may extend this exception to your
- * version of the file(s), but you are not obligated to do so.  If you
- * do not wish to do so, delete this exception statement from your
- * version.  If you delete this exception statement from all source
- * files in the program, then also delete it here.
- */
-/* copyright --> */
-#ifndef _D_DEFAULT_BT_CONTEXT_H_
-#define _D_DEFAULT_BT_CONTEXT_H_
-
-#include "BtContext.h"
-
-#include <iosfwd>
-
-#include "IntSequence.h"
-
-namespace aria2 {
-
-class Randomizer;
-class Logger;
-class BDE;
-
-#define INFO_HASH_LENGTH 20
-#define PIECE_HASH_LENGTH 20
-
-class DefaultBtContext : public BtContext {
-private:
-  unsigned char infoHash[INFO_HASH_LENGTH];
-  std::string infoHashString;
-  std::deque<std::string> pieceHashes;
-  FILE_MODE fileMode;
-  uint64_t totalLength;
-  size_t pieceLength;
-  std::string name;
-  size_t numPieces;
-  std::string peerId;
-  std::string _peerIdPrefix;
-  std::deque<SharedHandle<AnnounceTier> > announceTiers;
-  std::deque<std::pair<std::string, uint16_t> > _nodes;
-  SharedHandle<Randomizer> _randomizer;
-
-  RequestGroup* _ownerRequestGroup;
-
-  Logger* _logger;
-
-  static const std::string C_NAME;
-
-  static const std::string C_NAME_UTF8;
-
-  static const std::string C_FILES;
-
-  static const std::string C_LENGTH;
-
-  static const std::string C_PATH;
-
-  static const std::string C_PATH_UTF8;
-
-  static const std::string C_INFO;
-
-  static const std::string C_PIECES;
-
-  static const std::string C_PIECE_LENGTH;
-
-  static const std::string C_PRIVATE;
-
-  // This is just a string "1". Used as a value of "private" flag.
-  static const std::string C_PRIVATE_ON;
-
-  static const std::string C_URL_LIST;
-
-  static const std::string C_ANNOUNCE;
-
-  static const std::string C_ANNOUNCE_LIST;
-
-  static const std::string C_NODES;
-
-  void clear();
-  void extractPieceHash(const std::string& hashData, size_t hashLength);
-  void extractFileEntries(const BDE& infoDic,
-			  const std::string& defaultName,
-			  const std::string& overrideName,
-			  const std::deque<std::string>& urlList);
-  void extractAnnounceURI(const BDE& announceData);
-  void extractAnnounceList(const BDE& announceListData);
-  void extractAnnounce(const BDE& rootDict);
-
-  void extractUrlList(std::deque<std::string>& uris, const BDE& obj);
-
-  void extractNodes(const BDE& nodes);
-
-  void processRootDictionary(const BDE& rootDic,
-			     const std::string& defaultName,
-			     const std::string& overrideName);
-
- public:
-  DefaultBtContext();
-  virtual ~DefaultBtContext();
-
-  virtual const unsigned char* getInfoHash() const;
-
-  virtual size_t getInfoHashLength() const;
-
-  virtual const std::string& getInfoHashAsString() const;
-
-  virtual const std::string& getPieceHash(size_t index) const;
-
-  virtual const std::deque<std::string>& getPieceHashes() const
-  {
-    return pieceHashes;
-  }
-
-  virtual uint64_t getTotalLength() const;
-
-  virtual bool knowsTotalLength() const;
-
-  virtual FILE_MODE getFileMode() const;
-
-  virtual const std::string& getPieceHashAlgo() const;
-
-  virtual const std::deque<SharedHandle<AnnounceTier> >&
-  getAnnounceTiers() const;
-
-  // Note: Before calling load* function, call setDir() to specify
-  // directory.  Setting directory after load* function doesn't change
-  // the output file path.
-  virtual void load(const std::string& torrentFile,
-		    const std::string& overrideName = "");
-
-  void loadFromMemory(const unsigned char* content, size_t length,
-		      const std::string& defaultName,
-		      const std::string& overrideName = "");
-
-  void loadFromMemory(const std::string& context,
-		      const std::string& defaultName,
-		      const std::string& overrideName = "")
-  {
-    loadFromMemory(reinterpret_cast<const unsigned char*>(context.c_str()),
-		   context.size(), defaultName, overrideName);
-  }
-
-  virtual const std::string& getName() const;
-
-  virtual size_t getPieceLength() const;
-  
-  virtual size_t getNumPieces() const;
-
-  virtual std::string getActualBasePath() const;
-
-  virtual const unsigned char* getPeerId() {
-    if(peerId.empty()) {
-      peerId = generatePeerId();
-    }
-    return reinterpret_cast<const unsigned char*>(peerId.c_str());
-  }
-
-  virtual void computeFastSet
-  (std::deque<size_t>& fastSet, const std::string& ipaddr, size_t fastSetSize);
-
-  virtual RequestGroup* getOwnerRequestGroup()
-  {
-    return _ownerRequestGroup;
-  }
-
-  virtual std::deque<std::pair<std::string, uint16_t> >& getNodes();
-
-  virtual void setFileFilter(IntSequence seq);
-
-  std::string generatePeerId() const;
-
-  void setPeerIdPrefix(const std::string& peerIdPrefix)
-  {
-    _peerIdPrefix = peerIdPrefix;
-  }
-
-  // for unit test
-  void setInfoHash(const unsigned char* infoHash);
-
-  void setNumPieces(size_t numPieces)
-  {
-    this->numPieces = numPieces;
-  }
-   
-  void setOwnerRequestGroup(RequestGroup* owner)
-  {
-    _ownerRequestGroup = owner;
-  }
-
-  void setRandomizer(const SharedHandle<Randomizer>& randomizer);
-
-  // Sets file path for spcified index. index starts from 1. The index
-  // is the same used in BtContext::setFileFilter().  Please note that
-  // path is not the actual file path. The actual file path is
-  // getDir()+"/"+path.
-  void setFilePathWithIndex(size_t index, const std::string& path);
-
-  friend std::ostream& operator<<(std::ostream& o, const DefaultBtContext& ctx);
-
-  static const std::string DEFAULT_PEER_ID_PREFIX;
-};
-
-typedef SharedHandle<DefaultBtContext> DefaultBtContextHandle;
-
-} // namespace aria2
-
-#endif // _D_DEFAULT_BT_CONTEXT_H_
diff --git a/src/DefaultBtInteractive.cc b/src/DefaultBtInteractive.cc
index 5d712744..a69a9cdf 100644
--- a/src/DefaultBtInteractive.cc
+++ b/src/DefaultBtInteractive.cc
@@ -54,7 +54,7 @@
 #include "DHTNode.h"
 #include "Peer.h"
 #include "Piece.h"
-#include "BtContext.h"
+#include "DownloadContext.h"
 #include "PieceStorage.h"
 #include "PeerStorage.h"
 #include "BtRuntime.h"
@@ -68,13 +68,15 @@
 #include "StringFormat.h"
 #include "RequestGroup.h"
 #include "RequestGroupMan.h"
+#include "bittorrent_helper.h"
 
 namespace aria2 {
 
 DefaultBtInteractive::DefaultBtInteractive
-(const SharedHandle<BtContext>& btContext, const SharedHandle<Peer>& peer)
+(const SharedHandle<DownloadContext>& downloadContext,
+ const SharedHandle<Peer>& peer)
   :
-  _btContext(btContext),
+  _downloadContext(downloadContext),
   peer(peer),
   logger(LogFactory::getInstance()),
   allowedFastSetSize(10),
@@ -88,8 +90,8 @@ DefaultBtInteractive::~DefaultBtInteractive() {}
 
 void DefaultBtInteractive::initiateHandshake() {
   SharedHandle<BtMessage> message =
-    messageFactory->createHandshakeMessage(_btContext->getInfoHash(),
-					   _btContext->getPeerId());
+    messageFactory->createHandshakeMessage
+    (bittorrent::getInfoHash(_downloadContext), bittorrent::getStaticPeerId());
   dispatcher->addMessageToQueue(message);
   dispatcher->sendMessages();
 }
@@ -100,7 +102,7 @@ BtMessageHandle DefaultBtInteractive::receiveHandshake(bool quickReply) {
   if(message.isNull()) {
     return SharedHandle<BtMessage>();
   }
-  if(memcmp(message->getPeerId(), _btContext->getPeerId(),
+  if(memcmp(message->getPeerId(), bittorrent::getStaticPeerId(),
 	    PEER_ID_LENGTH) == 0) {
     throw DL_ABORT_EX
       (StringFormat
@@ -187,9 +189,12 @@ void DefaultBtInteractive::addBitfieldMessageToQueue() {
 
 void DefaultBtInteractive::addAllowedFastMessageToQueue() {
   if(peer->isFastExtensionEnabled()) {
-    std::deque<size_t> fastSet;
-    _btContext->computeFastSet(fastSet, peer->ipaddr, allowedFastSetSize);
-    for(std::deque<size_t>::const_iterator itr = fastSet.begin();
+    std::vector<size_t> fastSet;
+    bittorrent::computeFastSet(fastSet, peer->ipaddr,
+			       _downloadContext->getNumPieces(),
+			       bittorrent::getInfoHash(_downloadContext),
+			       allowedFastSetSize);
+    for(std::vector<size_t>::const_iterator itr = fastSet.begin();
 	itr != fastSet.end(); ++itr) {
       dispatcher->addMessageToQueue
 	(messageFactory->createAllowedFastMessage(*itr));
@@ -239,7 +244,7 @@ size_t DefaultBtInteractive::receiveMessages() {
   size_t msgcount = 0;
   for(int i = 0; i < 50; ++i) {
     if(_requestGroupMan->doesOverallDownloadSpeedExceed() ||
-       _btContext->getOwnerRequestGroup()->doesDownloadSpeedExceed()) {
+       _downloadContext->getOwnerRequestGroup()->doesDownloadSpeedExceed()) {
       break;
     }
     BtMessageHandle message = btMessageReceiver->receiveMessage();
diff --git a/src/DefaultBtInteractive.h b/src/DefaultBtInteractive.h
index ee522aed..1129dbeb 100644
--- a/src/DefaultBtInteractive.h
+++ b/src/DefaultBtInteractive.h
@@ -43,7 +43,7 @@
 
 namespace aria2 {
 
-class BtContext;
+class DownloadContext;
 class BtRuntime;
 class PieceStorage;
 class PeerStorage;
@@ -97,7 +97,7 @@ class DefaultBtInteractive : public BtInteractive {
 private:
   int32_t cuid;
 
-  SharedHandle<BtContext> _btContext;
+  SharedHandle<DownloadContext> _downloadContext;
 
   SharedHandle<BtRuntime> _btRuntime;
 
@@ -151,7 +151,7 @@ private:
   void addPortMessageToQueue();
 
 public:
-  DefaultBtInteractive(const SharedHandle<BtContext>& btContext,
+  DefaultBtInteractive(const SharedHandle<DownloadContext>& downloadContext,
 		       const SharedHandle<Peer>& peer);
 
   virtual ~DefaultBtInteractive();
diff --git a/src/DefaultBtMessageDispatcher.cc b/src/DefaultBtMessageDispatcher.cc
index 1adc3565..fa201198 100644
--- a/src/DefaultBtMessageDispatcher.cc
+++ b/src/DefaultBtMessageDispatcher.cc
@@ -42,7 +42,7 @@
 #include "BtChokingEvent.h"
 #include "BtMessageFactory.h"
 #include "message.h"
-#include "BtContext.h"
+#include "DownloadContext.h"
 #include "PeerStorage.h"
 #include "PieceStorage.h"
 #include "BtMessage.h"
@@ -87,7 +87,7 @@ void DefaultBtMessageDispatcher::sendMessages() {
     messageQueue.pop_front();
     if(msg->isUploading() && !msg->isSendingInProgress()) {
       if(_requestGroupMan->doesOverallUploadSpeedExceed() ||
-	 btContext->getOwnerRequestGroup()->doesUploadSpeedExceed()) {
+	 _downloadContext->getOwnerRequestGroup()->doesUploadSpeedExceed()) {
 	tempQueue.push_back(msg);
 	continue;
       }
@@ -412,9 +412,10 @@ void DefaultBtMessageDispatcher::setPeer(const SharedHandle<Peer>& peer)
   this->peer = peer;
 }
 
-void DefaultBtMessageDispatcher::setBtContext(const BtContextHandle& btContext)
+void DefaultBtMessageDispatcher::setDownloadContext
+(const SharedHandle<DownloadContext>& downloadContext)
 {
-  this->btContext = btContext;
+  _downloadContext = downloadContext;
 }
 
 void DefaultBtMessageDispatcher::setPieceStorage
diff --git a/src/DefaultBtMessageDispatcher.h b/src/DefaultBtMessageDispatcher.h
index 2b3cc2a3..0b5caae6 100644
--- a/src/DefaultBtMessageDispatcher.h
+++ b/src/DefaultBtMessageDispatcher.h
@@ -40,7 +40,7 @@
 
 namespace aria2 {
 
-class BtContext;
+class DownloadContext;
 class PeerStorage;
 class PieceStorage;
 class BtMessage;
@@ -55,7 +55,7 @@ private:
   int32_t cuid;
   std::deque<SharedHandle<BtMessage> > messageQueue;
   std::deque<RequestSlot> requestSlots;
-  SharedHandle<BtContext> btContext;
+  SharedHandle<DownloadContext> _downloadContext;
   SharedHandle<PeerStorage> _peerStorage;
   SharedHandle<PieceStorage> _pieceStorage;
   WeakHandle<BtMessageFactory> messageFactory;
@@ -116,7 +116,7 @@ public:
 
   void setPeer(const SharedHandle<Peer>& peer);
 
-  void setBtContext(const SharedHandle<BtContext>& btContext);
+  void setDownloadContext(const SharedHandle<DownloadContext>& downloadContext);
 
   void setPieceStorage(const SharedHandle<PieceStorage>& pieceStorage);
 
diff --git a/src/DefaultBtMessageFactory.cc b/src/DefaultBtMessageFactory.cc
index 0c6306a7..17bc280c 100644
--- a/src/DefaultBtMessageFactory.cc
+++ b/src/DefaultBtMessageFactory.cc
@@ -61,11 +61,12 @@
 #include "ExtensionMessage.h"
 #include "Peer.h"
 #include "Piece.h"
-#include "BtContext.h"
+#include "DownloadContext.h"
 #include "PieceStorage.h"
 #include "PeerStorage.h"
 #include "StringFormat.h"
 #include "ExtensionMessageFactory.h"
+#include "bittorrent_helper.h"
 
 namespace aria2 {
 
@@ -112,7 +113,7 @@ DefaultBtMessageFactory::createBtMessage(const unsigned char* data, size_t dataL
       {
 	SharedHandle<BtMessageValidator> v
 	  (new IndexBtMessageValidator((BtHaveMessage*)msg.get(),
-				       btContext->getNumPieces()));
+				       _downloadContext->getNumPieces()));
 	msg->setBtMessageValidator(v);
       }
       break;
@@ -121,7 +122,7 @@ DefaultBtMessageFactory::createBtMessage(const unsigned char* data, size_t dataL
       {
 	SharedHandle<BtMessageValidator> v
 	  (new BtBitfieldMessageValidator((BtBitfieldMessage*)msg.get(),
-					  btContext->getNumPieces()));
+					  _downloadContext->getNumPieces()));
 	msg->setBtMessageValidator(v);
       }
       break;
@@ -130,7 +131,7 @@ DefaultBtMessageFactory::createBtMessage(const unsigned char* data, size_t dataL
       SharedHandle<BtMessageValidator> validator
 	(new RangeBtMessageValidator
 	 (temp.get(),
-	  btContext->getNumPieces(),
+	  _downloadContext->getNumPieces(),
 	  _pieceStorage->getPieceLength(temp->getIndex())));
       temp->setBtMessageValidator(validator);
       msg = temp;
@@ -141,7 +142,7 @@ DefaultBtMessageFactory::createBtMessage(const unsigned char* data, size_t dataL
       SharedHandle<BtMessageValidator> validator
 	(new RangeBtMessageValidator
 	 (temp.get(),
-	  btContext->getNumPieces(),
+	  _downloadContext->getNumPieces(),
 	  _pieceStorage->getPieceLength(temp->getIndex())));
       temp->setBtMessageValidator(validator);
       msg = temp;
@@ -151,9 +152,10 @@ DefaultBtMessageFactory::createBtMessage(const unsigned char* data, size_t dataL
       BtPieceMessageHandle temp = BtPieceMessage::create(data, dataLength);
       BtMessageValidatorHandle validator
 	(new BtPieceMessageValidator(temp.get(),
-				     btContext->getNumPieces(),
+				     _downloadContext->getNumPieces(),
 				     _pieceStorage->getPieceLength(temp->getIndex())));
       temp->setBtMessageValidator(validator);
+      temp->setDownloadContext(_downloadContext);
       msg = temp;
       break;
     }
@@ -168,7 +170,7 @@ DefaultBtMessageFactory::createBtMessage(const unsigned char* data, size_t dataL
       SharedHandle<BtMessageValidator> validator
 	(new RangeBtMessageValidator
 	 (temp.get(),
-	  btContext->getNumPieces(),
+	  _downloadContext->getNumPieces(),
 	  _pieceStorage->getPieceLength(temp->getIndex())));
       temp->setBtMessageValidator(validator);
       msg = temp;
@@ -177,7 +179,8 @@ DefaultBtMessageFactory::createBtMessage(const unsigned char* data, size_t dataL
     case BtSuggestPieceMessage::ID: {
       BtSuggestPieceMessageHandle temp = BtSuggestPieceMessage::create(data, dataLength);
       SharedHandle<BtMessageValidator> validator
-	(new IndexBtMessageValidator(temp.get(), btContext->getNumPieces()));
+	(new IndexBtMessageValidator(temp.get(),
+				     _downloadContext->getNumPieces()));
       temp->setBtMessageValidator(validator);
       msg = temp;
       break;
@@ -185,7 +188,8 @@ DefaultBtMessageFactory::createBtMessage(const unsigned char* data, size_t dataL
     case BtAllowedFastMessage::ID: {
       BtAllowedFastMessageHandle temp = BtAllowedFastMessage::create(data, dataLength);
       SharedHandle<BtMessageValidator> validator
-	(new IndexBtMessageValidator(temp.get(), btContext->getNumPieces()));
+	(new IndexBtMessageValidator(temp.get(),
+				     _downloadContext->getNumPieces()));
       temp->setBtMessageValidator(validator);
       msg = temp;
       break;
@@ -219,7 +223,6 @@ DefaultBtMessageFactory::createBtMessage(const unsigned char* data, size_t dataL
 void DefaultBtMessageFactory::setCommonProperty(const AbstractBtMessageHandle& msg) {
   msg->setCuid(cuid);
   msg->setPeer(peer);
-  msg->setBtContext(btContext);
   msg->setPieceStorage(_pieceStorage);
   msg->setBtMessageDispatcher(dispatcher);
   msg->setBtRequestFactory(requestFactory);
@@ -232,8 +235,8 @@ DefaultBtMessageFactory::createHandshakeMessage(const unsigned char* data, size_
 {
   SharedHandle<BtHandshakeMessage> msg = BtHandshakeMessage::create(data, dataLength);
   BtMessageValidatorHandle validator
-    (new BtHandshakeMessageValidator(msg.get(),
-				     btContext->getInfoHash()));
+    (new BtHandshakeMessageValidator
+     (msg.get(), bittorrent::getInfoHash(_downloadContext)));
   msg->setBtMessageValidator(validator);
   setCommonProperty(msg);
   return msg;
@@ -245,8 +248,8 @@ DefaultBtMessageFactory::createHandshakeMessage(const unsigned char* infoHash,
 {
   SharedHandle<BtHandshakeMessage> msg(new BtHandshakeMessage(infoHash, peerId));
   BtMessageValidatorHandle validator
-    (new BtHandshakeMessageValidator(msg.get(),
-				     btContext->getInfoHash()));
+    (new BtHandshakeMessageValidator
+     (msg.get(), bittorrent::getInfoHash(_downloadContext)));
   msg->setBtMessageValidator(validator);
   msg->setDHTEnabled(_dhtEnabled);
   setCommonProperty(msg);
@@ -264,7 +267,7 @@ DefaultBtMessageFactory::createRequestMessage(const PieceHandle& piece, size_t b
   SharedHandle<BtMessageValidator> validator
     (new RangeBtMessageValidator
      (msg.get(),
-      btContext->getNumPieces(),
+      _downloadContext->getNumPieces(),
       _pieceStorage->getPieceLength(msg->getIndex())));
   msg->setBtMessageValidator(validator);
   setCommonProperty(msg);
@@ -278,7 +281,7 @@ DefaultBtMessageFactory::createCancelMessage(size_t index, uint32_t begin, size_
   SharedHandle<BtMessageValidator> validator
     (new RangeBtMessageValidator
      (msg.get(),
-      btContext->getNumPieces(),
+      _downloadContext->getNumPieces(),
       _pieceStorage->getPieceLength(index)));
   msg->setBtMessageValidator(validator);
   setCommonProperty(msg);
@@ -291,9 +294,10 @@ DefaultBtMessageFactory::createPieceMessage(size_t index, uint32_t begin, size_t
   BtPieceMessageHandle msg(new BtPieceMessage(index, begin, length));
   BtMessageValidatorHandle validator
     (new BtPieceMessageValidator(msg.get(),
-				btContext->getNumPieces(),
+				_downloadContext->getNumPieces(),
 				_pieceStorage->getPieceLength(index)));
   msg->setBtMessageValidator(validator);
+  msg->setDownloadContext(_downloadContext);
   setCommonProperty(msg);
   return msg;
 }
@@ -303,7 +307,7 @@ DefaultBtMessageFactory::createHaveMessage(size_t index)
 {
   BtHaveMessageHandle msg(new BtHaveMessage(index));
   SharedHandle<BtMessageValidator> v
-    (new IndexBtMessageValidator(msg.get(), btContext->getNumPieces()));
+    (new IndexBtMessageValidator(msg.get(), _downloadContext->getNumPieces()));
   msg->setBtMessageValidator(v);
   setCommonProperty(msg);
   return msg;
@@ -349,7 +353,7 @@ DefaultBtMessageFactory::createBitfieldMessage()
 			   _pieceStorage->getBitfieldLength()));
   SharedHandle<BtMessageValidator> v
     (new BtBitfieldMessageValidator(msg.get(),
-				    btContext->getNumPieces()));
+				    _downloadContext->getNumPieces()));
   msg->setBtMessageValidator(v);
   setCommonProperty(msg);
   return msg;
@@ -386,7 +390,7 @@ DefaultBtMessageFactory::createRejectMessage(size_t index, uint32_t begin, size_
   SharedHandle<BtMessageValidator> validator
     (new RangeBtMessageValidator
      (msg.get(),
-      btContext->getNumPieces(),
+      _downloadContext->getNumPieces(),
       _pieceStorage->getPieceLength(index)));
   msg->setBtMessageValidator(validator);
   setCommonProperty(msg);
@@ -398,7 +402,7 @@ DefaultBtMessageFactory::createAllowedFastMessage(size_t index)
 {
   BtAllowedFastMessageHandle msg(new BtAllowedFastMessage(index));
   SharedHandle<BtMessageValidator> validator
-    (new IndexBtMessageValidator(msg.get(), btContext->getNumPieces()));
+    (new IndexBtMessageValidator(msg.get(), _downloadContext->getNumPieces()));
   msg->setBtMessageValidator(validator);
   setCommonProperty(msg);
   return msg;
@@ -435,9 +439,10 @@ void DefaultBtMessageFactory::setPeer(const SharedHandle<Peer>& peer)
   this->peer = peer;
 }
 
-void DefaultBtMessageFactory::setBtContext(const SharedHandle<BtContext>& btContext)
+void DefaultBtMessageFactory::setDownloadContext
+(const SharedHandle<DownloadContext>& downloadContext)
 {
-  this->btContext = btContext;
+  _downloadContext = downloadContext;
 }
 
 void DefaultBtMessageFactory::setPieceStorage
diff --git a/src/DefaultBtMessageFactory.h b/src/DefaultBtMessageFactory.h
index c2ef06fc..7b289946 100644
--- a/src/DefaultBtMessageFactory.h
+++ b/src/DefaultBtMessageFactory.h
@@ -39,7 +39,7 @@
 
 namespace aria2 {
 
-class BtContext;
+class DownloadContext;
 class PieceStorage;
 class PeerStorage;
 class Peer;
@@ -56,7 +56,7 @@ class DHTTaskFactory;
 class DefaultBtMessageFactory : public BtMessageFactory {
 private:
   int32_t cuid;
-  SharedHandle<BtContext> btContext;
+  SharedHandle<DownloadContext> _downloadContext;
   SharedHandle<PieceStorage> _pieceStorage;
   SharedHandle<PeerStorage> _peerStorage;
   SharedHandle<Peer> peer;
@@ -134,7 +134,7 @@ public:
 
   void setPeer(const SharedHandle<Peer>& peer);
 
-  void setBtContext(const SharedHandle<BtContext>& btContext);
+  void setDownloadContext(const SharedHandle<DownloadContext>& downloadContext);
 
   void setPieceStorage(const SharedHandle<PieceStorage>& pieceStorage);
 
diff --git a/src/DefaultBtMessageReceiver.cc b/src/DefaultBtMessageReceiver.cc
index d6afbb70..9e5ee0f4 100644
--- a/src/DefaultBtMessageReceiver.cc
+++ b/src/DefaultBtMessageReceiver.cc
@@ -38,13 +38,14 @@
 
 #include "BtHandshakeMessage.h"
 #include "message.h"
-#include "BtContext.h"
+#include "DownloadContext.h"
 #include "Peer.h"
 #include "PeerConnection.h"
 #include "BtMessageDispatcher.h"
 #include "BtMessageFactory.h"
 #include "Logger.h"
 #include "LogFactory.h"
+#include "bittorrent_helper.h"
 
 namespace aria2 {
 
@@ -71,7 +72,8 @@ DefaultBtMessageReceiver::receiveHandshake(bool quickReply)
   if(!handshakeSent && quickReply && dataLength >= 48) {
     handshakeSent = true;
     // check info_hash
-    if(memcmp(btContext->getInfoHash(), &data[28], INFO_HASH_LENGTH) == 0) {
+    if(memcmp(bittorrent::getInfoHash(_downloadContext), &data[28],
+	      INFO_HASH_LENGTH) == 0) {
       sendHandshake();
     }
   }
@@ -92,8 +94,8 @@ DefaultBtMessageReceiver::receiveAndSendHandshake()
 
 void DefaultBtMessageReceiver::sendHandshake() {
   SharedHandle<BtMessage> msg =
-    messageFactory->createHandshakeMessage(btContext->getInfoHash(),
-					   btContext->getPeerId());
+    messageFactory->createHandshakeMessage
+    (bittorrent::getInfoHash(_downloadContext), bittorrent::getStaticPeerId());
   dispatcher->addMessageToQueue(msg);
   dispatcher->sendMessages();
 }
@@ -114,9 +116,10 @@ BtMessageHandle DefaultBtMessageReceiver::receiveMessage() {
   }
 }
 
-void DefaultBtMessageReceiver::setBtContext(const SharedHandle<BtContext>& btContext)
+void DefaultBtMessageReceiver::setDownloadContext
+(const SharedHandle<DownloadContext>& downloadContext)
 {
-  this->btContext = btContext;
+  _downloadContext = downloadContext;
 }
 
 void DefaultBtMessageReceiver::setPeer(const SharedHandle<Peer>& peer)
diff --git a/src/DefaultBtMessageReceiver.h b/src/DefaultBtMessageReceiver.h
index 8344eb10..a5bbbf27 100644
--- a/src/DefaultBtMessageReceiver.h
+++ b/src/DefaultBtMessageReceiver.h
@@ -39,7 +39,7 @@
 
 namespace aria2 {
 
-class BtContext;
+class DownloadContext;
 class Peer;
 class PeerConnection;
 class BtMessageDispatcher;
@@ -50,7 +50,7 @@ class DefaultBtMessageReceiver : public BtMessageReceiver {
 private:
   int32_t cuid;
   bool handshakeSent;
-  SharedHandle<BtContext> btContext;
+  SharedHandle<DownloadContext> _downloadContext;
   SharedHandle<Peer> peer;
   WeakHandle<PeerConnection> peerConnection;
   WeakHandle<BtMessageDispatcher> dispatcher;
@@ -77,7 +77,7 @@ public:
     return cuid;
   }
 
-  void setBtContext(const SharedHandle<BtContext>& btContext);
+  void setDownloadContext(const SharedHandle<DownloadContext>& downloadContext);
 
   void setPeer(const SharedHandle<Peer>& peer);
 
diff --git a/src/DefaultBtProgressInfoFile.cc b/src/DefaultBtProgressInfoFile.cc
index ef2d7474..9b573f95 100644
--- a/src/DefaultBtProgressInfoFile.cc
+++ b/src/DefaultBtProgressInfoFile.cc
@@ -38,13 +38,8 @@
 #include <cstring>
 #include <fstream>
 
-#include "BtContext.h"
 #include "PieceStorage.h"
 #include "Piece.h"
-#ifdef ENABLE_BITTORRENT
-#include "PeerStorage.h"
-#include "BtRuntime.h"
-#endif // ENABLE_BITTORRENT
 #include "BitfieldMan.h"
 #include "Option.h"
 #include "TransferStat.h"
@@ -59,6 +54,12 @@
 #include "DownloadFailureException.h"
 #include "StringFormat.h"
 #include "array_fun.h"
+#include "DownloadContext.h"
+#ifdef ENABLE_BITTORRENT
+# include "PeerStorage.h"
+# include "BtRuntime.h"
+# include "bittorrent_helper.h"
+#endif // ENABLE_BITTORRENT
 
 namespace aria2 {
 
@@ -67,13 +68,13 @@ const std::string DefaultBtProgressInfoFile::V0001("0001");
 
 static std::string createFilename(const SharedHandle<DownloadContext>& dctx)
 {
-  std::string t = dctx->getActualBasePath();
+  std::string t = dctx->getBasePath();
   t += ".aria2";
   return t;
 }
 
 DefaultBtProgressInfoFile::DefaultBtProgressInfoFile
-(const DownloadContextHandle& dctx,
+(const SharedHandle<DownloadContext>& dctx,
  const PieceStorageHandle& pieceStorage,
  const Option* option):
   _dctx(dctx),
@@ -123,13 +124,12 @@ void DefaultBtProgressInfoFile::save() {
     if(torrentDownload) {
       // infoHashLength:
       // length: 32 bits
-      BtContextHandle btContext(dynamic_pointer_cast<BtContext>(_dctx));
-      uint32_t infoHashLengthNL = htonl(btContext->getInfoHashLength());
+      const unsigned char* infoHash = bittorrent::getInfoHash(_dctx);
+      uint32_t infoHashLengthNL = htonl(INFO_HASH_LENGTH);
       o.write(reinterpret_cast<const char*>(&infoHashLengthNL),
 	      sizeof(infoHashLengthNL));
       // infoHash:
-      o.write(reinterpret_cast<const char*>(btContext->getInfoHash()),
-	      btContext->getInfoHashLength());
+      o.write(reinterpret_cast<const char*>(infoHash), INFO_HASH_LENGTH);
     } else {
       // infoHashLength:
       // length: 32 bits
@@ -240,15 +240,16 @@ void DefaultBtProgressInfoFile::load()
       array_ptr<unsigned char> savedInfoHash(new unsigned char[infoHashLength]);
       in.read(reinterpret_cast<char*>
 	      (static_cast<unsigned char*>(savedInfoHash)), infoHashLength);
-      BtContextHandle btContext(dynamic_pointer_cast<BtContext>(_dctx));
-      if(infoHashCheckEnabled &&
-	 Util::toHex(savedInfoHash, infoHashLength) !=
-	 btContext->getInfoHashAsString()) {
-	throw DL_ABORT_EX
-	  (StringFormat("info hash mismatch. expected: %s, actual: %s",
-			btContext->getInfoHashAsString().c_str(),
-			Util::toHex(savedInfoHash,
-				    infoHashLength).c_str()).str());
+      if(infoHashCheckEnabled) {
+	const unsigned char* infoHash = bittorrent::getInfoHash(_dctx);
+	if(infoHashLength != INFO_HASH_LENGTH ||
+	   memcmp(savedInfoHash, infoHash, INFO_HASH_LENGTH) != 0) {
+	  throw DL_ABORT_EX
+	    (StringFormat("info hash mismatch. expected: %s, actual: %s",
+			  Util::toHex(infoHash, INFO_HASH_LENGTH).c_str(),
+			  Util::toHex(savedInfoHash, infoHashLength).c_str()
+			  ).str());
+	}
       }
     }
 
diff --git a/src/DefaultBtRequestFactory.cc b/src/DefaultBtRequestFactory.cc
index f14462f1..059c411c 100644
--- a/src/DefaultBtRequestFactory.cc
+++ b/src/DefaultBtRequestFactory.cc
@@ -40,7 +40,6 @@
 #include "Logger.h"
 #include "Piece.h"
 #include "Peer.h"
-#include "BtContext.h"
 #include "PieceStorage.h"
 #include "BtMessageDispatcher.h"
 #include "BtMessageFactory.h"
@@ -235,11 +234,6 @@ void DefaultBtRequestFactory::getTargetPieceIndexes
 		 mem_fun_sh(&Piece::getIndex));
 }
 
-void DefaultBtRequestFactory::setBtContext(const SharedHandle<BtContext>& btContext)
-{
-  this->btContext = btContext;
-}
-
 void DefaultBtRequestFactory::setPieceStorage
 (const SharedHandle<PieceStorage>& pieceStorage)
 {
diff --git a/src/DefaultBtRequestFactory.h b/src/DefaultBtRequestFactory.h
index a4000368..bcf8c8cf 100644
--- a/src/DefaultBtRequestFactory.h
+++ b/src/DefaultBtRequestFactory.h
@@ -39,7 +39,6 @@
 
 namespace aria2 {
 
-class BtContext;
 class PieceStorage;
 class Peer;
 class BtMessageDispatcher;
@@ -50,7 +49,6 @@ class Logger;
 class DefaultBtRequestFactory : public BtRequestFactory {
 private:
   int32_t cuid;
-  SharedHandle<BtContext> btContext;
   SharedHandle<PieceStorage> _pieceStorage;
   SharedHandle<Peer> peer;
   WeakHandle<BtMessageDispatcher> dispatcher;
@@ -96,8 +94,6 @@ public:
     this->cuid = cuid;
   }
 
-  void setBtContext(const SharedHandle<BtContext>& btContext);
-
   void setPieceStorage(const SharedHandle<PieceStorage>& pieceStorage);
 
   void setPeer(const SharedHandle<Peer>& peer);
diff --git a/src/DefaultExtensionMessageFactory.cc b/src/DefaultExtensionMessageFactory.cc
index 6210d108..f28680a4 100644
--- a/src/DefaultExtensionMessageFactory.cc
+++ b/src/DefaultExtensionMessageFactory.cc
@@ -33,7 +33,6 @@
  */
 /* copyright --> */
 #include "DefaultExtensionMessageFactory.h"
-#include "BtContext.h"
 #include "Peer.h"
 #include "DlAbortEx.h"
 #include "HandshakeExtensionMessage.h"
@@ -50,10 +49,8 @@ DefaultExtensionMessageFactory::DefaultExtensionMessageFactory():
   _logger(LogFactory::getInstance()) {}
 
 DefaultExtensionMessageFactory::DefaultExtensionMessageFactory
-(const BtContextHandle& btContext,
- const PeerHandle& peer,
+(const PeerHandle& peer,
  const SharedHandle<ExtensionMessageRegistry>& registry):
-  _btContext(btContext),
   _peer(peer),
   _registry(registry),
   _logger(LogFactory::getInstance()) {}
@@ -67,7 +64,6 @@ DefaultExtensionMessageFactory::createMessage(const unsigned char* data, size_t
   if(extensionMessageID == 0) {
     // handshake
     HandshakeExtensionMessageHandle m = HandshakeExtensionMessage::create(data, length);
-    m->setBtContext(_btContext);
     m->setPeer(_peer);
     return m;
   } else {
@@ -91,11 +87,6 @@ DefaultExtensionMessageFactory::createMessage(const unsigned char* data, size_t
   }
 }
 
-void DefaultExtensionMessageFactory::setBtContext(const BtContextHandle& btContext)
-{
-  _btContext = btContext;
-}
-
 void DefaultExtensionMessageFactory::setPeerStorage
 (const SharedHandle<PeerStorage>& peerStorage)
 {
diff --git a/src/DefaultExtensionMessageFactory.h b/src/DefaultExtensionMessageFactory.h
index a3ffd309..dfc1c0ec 100644
--- a/src/DefaultExtensionMessageFactory.h
+++ b/src/DefaultExtensionMessageFactory.h
@@ -39,7 +39,6 @@
 
 namespace aria2 {
 
-class BtContext;
 class PeerStorage;
 class Peer;
 class Logger;
@@ -47,8 +46,6 @@ class ExtensionMessageRegistry;
 
 class DefaultExtensionMessageFactory:public ExtensionMessageFactory {
 private:
-  SharedHandle<BtContext> _btContext;
-
   SharedHandle<PeerStorage> _peerStorage;
 
   SharedHandle<Peer> _peer;
@@ -61,8 +58,7 @@ public:
   DefaultExtensionMessageFactory();
 
   DefaultExtensionMessageFactory
-  (const SharedHandle<BtContext>& btContext,
-   const SharedHandle<Peer>& peer,
+  (const SharedHandle<Peer>& peer,
    const SharedHandle<ExtensionMessageRegistry>& registry);
 
   virtual ~DefaultExtensionMessageFactory();
@@ -70,8 +66,6 @@ public:
   virtual SharedHandle<ExtensionMessage>
   createMessage(const unsigned char* data, size_t length);
 
-  void setBtContext(const SharedHandle<BtContext>& btContext);
-
   void setPeerStorage(const SharedHandle<PeerStorage>& peerStorage);
 
   void setPeer(const SharedHandle<Peer>& peer);
diff --git a/src/DefaultPeerStorage.cc b/src/DefaultPeerStorage.cc
index 18e36ceb..78116204 100644
--- a/src/DefaultPeerStorage.cc
+++ b/src/DefaultPeerStorage.cc
@@ -41,7 +41,6 @@
 #include "message.h"
 #include "a2time.h"
 #include "Peer.h"
-#include "BtContext.h"
 #include "BtRuntime.h"
 #include "BtSeederStateChoke.h"
 #include "BtLeecherStateChoke.h"
@@ -51,9 +50,7 @@ namespace aria2 {
 
 static const int MAX_PEER_LIST_SIZE = 1024;
 
-DefaultPeerStorage::DefaultPeerStorage(const BtContextHandle& btContext,
-				       const Option* option):
-  btContext(btContext),
+DefaultPeerStorage::DefaultPeerStorage(const Option* option):
   option(option),
   logger(LogFactory::getInstance()),
   removedPeerSessionDownloadLength(0),
diff --git a/src/DefaultPeerStorage.h b/src/DefaultPeerStorage.h
index 21f4b7ef..c52f0094 100644
--- a/src/DefaultPeerStorage.h
+++ b/src/DefaultPeerStorage.h
@@ -43,7 +43,6 @@
 
 namespace aria2 {
 
-class BtContext;
 class Option;
 class Logger;
 class BtRuntime;
@@ -53,7 +52,6 @@ class PieceStorage;
 
 class DefaultPeerStorage : public PeerStorage {
 private:
-  SharedHandle<BtContext> btContext;
   SharedHandle<BtRuntime> _btRuntime;
   SharedHandle<PieceStorage> _pieceStorage;
   const Option* option;
@@ -73,8 +71,7 @@ private:
 
   bool isPeerAlreadyAdded(const SharedHandle<Peer>& peer);
 public:
-  DefaultPeerStorage(const SharedHandle<BtContext>& btContext,
-		     const Option* option);
+  DefaultPeerStorage(const Option* option);
 
   virtual ~DefaultPeerStorage();
 
diff --git a/src/DefaultPieceStorage.cc b/src/DefaultPieceStorage.cc
index 3a707558..02547bf0 100644
--- a/src/DefaultPieceStorage.cc
+++ b/src/DefaultPieceStorage.cc
@@ -63,7 +63,7 @@
 namespace aria2 {
 
 DefaultPieceStorage::DefaultPieceStorage
-(const DownloadContextHandle& downloadContext, const Option* option):
+(const SharedHandle<DownloadContext>& downloadContext, const Option* option):
   downloadContext(downloadContext),
   bitfieldMan(BitfieldManFactory::getFactoryInstance()->
 	      createBitfieldMan(downloadContext->getPieceLength(),
@@ -421,10 +421,10 @@ size_t DefaultPieceStorage::getInFlightPieceCompletedLength() const
 // not unittested
 void DefaultPieceStorage::setupFileFilter()
 {
-  const std::deque<SharedHandle<FileEntry> >& fileEntries =
+  const std::vector<SharedHandle<FileEntry> >& fileEntries =
     downloadContext->getFileEntries();
   bool allSelected = true;
-  for(std::deque<SharedHandle<FileEntry> >::const_iterator i =
+  for(std::vector<SharedHandle<FileEntry> >::const_iterator i =
 	fileEntries.begin(); i != fileEntries.end(); ++i) {
     if(!(*i)->isRequested()) {
       allSelected = false;
@@ -434,7 +434,7 @@ void DefaultPieceStorage::setupFileFilter()
   if(allSelected) {
     return;
   }
-  for(std::deque<SharedHandle<FileEntry> >::const_iterator i =
+  for(std::vector<SharedHandle<FileEntry> >::const_iterator i =
 	fileEntries.begin(); i != fileEntries.end(); ++i) {
     if((*i)->isRequested()) {
       bitfieldMan->addFilter((*i)->getOffset(), (*i)->getLength());
@@ -465,11 +465,12 @@ bool DefaultPieceStorage::allDownloadFinished()
 // not unittested
 void DefaultPieceStorage::initStorage()
 {
-  if(downloadContext->getFileMode() == DownloadContext::SINGLE) {
+  if(downloadContext->getFileEntries().size() == 1) {
     logger->debug("Instantiating DirectDiskAdaptor");
     DirectDiskAdaptorHandle directDiskAdaptor(new DirectDiskAdaptor());
     directDiskAdaptor->setTotalLength(downloadContext->getTotalLength());
-    directDiskAdaptor->setFileEntries(downloadContext->getFileEntries());
+    directDiskAdaptor->setFileEntries(downloadContext->getFileEntries().begin(),
+				      downloadContext->getFileEntries().end());
 
     DiskWriterHandle writer =
       _diskWriterFactory->newDiskWriter(directDiskAdaptor->getFilePath());
@@ -480,10 +481,10 @@ void DefaultPieceStorage::initStorage()
     directDiskAdaptor->setDiskWriter(writer);
     this->diskAdaptor = directDiskAdaptor;
   } else {
-    // file mode == DownloadContext::MULTI
     logger->debug("Instantiating MultiDiskAdaptor");
     MultiDiskAdaptorHandle multiDiskAdaptor(new MultiDiskAdaptor());
-    multiDiskAdaptor->setFileEntries(downloadContext->getFileEntries());
+    multiDiskAdaptor->setFileEntries(downloadContext->getFileEntries().begin(),
+				     downloadContext->getFileEntries().end());
     if(option->getAsBool(PREF_ENABLE_DIRECT_IO)) {
       multiDiskAdaptor->allowDirectIO();
     }
diff --git a/src/DefaultSegmentManFactory.cc b/src/DefaultSegmentManFactory.cc
index 5ed7edef..8f020f98 100644
--- a/src/DefaultSegmentManFactory.cc
+++ b/src/DefaultSegmentManFactory.cc
@@ -42,8 +42,9 @@
 namespace aria2 {
 
 SegmentManHandle
-DefaultSegmentManFactory::createNewInstance(const DownloadContextHandle& dctx,
-					    const PieceStorageHandle& ps)
+DefaultSegmentManFactory::createNewInstance
+(const SharedHandle<DownloadContext>& dctx,
+ const PieceStorageHandle& ps)
 {
   SegmentManHandle segmentMan(new SegmentMan(_option, dctx, ps));
   return segmentMan;
diff --git a/src/DiskAdaptor.cc b/src/DiskAdaptor.cc
index 38e0b3ea..5e17eb2b 100644
--- a/src/DiskAdaptor.cc
+++ b/src/DiskAdaptor.cc
@@ -47,8 +47,4 @@ DiskAdaptor::DiskAdaptor():
 
 DiskAdaptor::~DiskAdaptor() {}
 
-void DiskAdaptor::setFileEntries(const FileEntries& fileEntries) {
-  this->fileEntries = fileEntries;
-}
-
 } // namespace aria2
diff --git a/src/DiskAdaptor.h b/src/DiskAdaptor.h
index 6e59826a..cb794391 100644
--- a/src/DiskAdaptor.h
+++ b/src/DiskAdaptor.h
@@ -38,7 +38,7 @@
 #include "BinaryStream.h"
 
 #include <string>
-#include <deque>
+#include <vector>
 
 #include "TimeA2.h"
 
@@ -50,7 +50,7 @@ class FileAllocationIterator;
 
 class DiskAdaptor:public BinaryStream {
 protected:
-  std::deque<SharedHandle<FileEntry> > fileEntries;
+  std::vector<SharedHandle<FileEntry> > fileEntries;
 #ifdef HAVE_POSIX_FALLOCATE
   bool _fallocate;
 #endif // HAVE_POSIX_FALLOCATE
@@ -73,9 +73,13 @@ public:
 
   virtual uint64_t size() = 0;
 
-  void setFileEntries(const std::deque<SharedHandle<FileEntry> >& fileEntries);
+  template<typename InputIterator>
+  void setFileEntries(InputIterator first, InputIterator last)
+  {
+    fileEntries.assign(first, last);
+  }
 
-  const std::deque<SharedHandle<FileEntry> >& getFileEntries() const
+  const std::vector<SharedHandle<FileEntry> >& getFileEntries() const
   {
     return fileEntries;
   }
diff --git a/src/DownloadContext.cc b/src/DownloadContext.cc
index a5dda4d2..f002eb3d 100644
--- a/src/DownloadContext.cc
+++ b/src/DownloadContext.cc
@@ -37,29 +37,30 @@
 #include <algorithm>
 
 #include "FileEntry.h"
+#include "StringFormat.h"
 
 namespace aria2 {
 
 DownloadContext::DownloadContext():
   _dir("."),
+  _pieceLength(0),
+  _knowsTotalLength(true),
+  _ownerRequestGroup(0),
   _downloadStartTime(0),
   _downloadStopTime(_downloadStartTime) {}
 
-DownloadContext::~DownloadContext() {}
-
-void DownloadContext::setDir(const std::string& dir)
-{
-  _dir = dir;
-}
-
-SharedHandle<Signature> DownloadContext::getSignature() const
-{
-  return _signature;
-}
-
-void DownloadContext::setSignature(const SharedHandle<Signature>& signature)
+DownloadContext::DownloadContext(size_t pieceLength,
+				 uint64_t totalLength,
+				 const std::string& path):
+  _dir("."),
+  _pieceLength(pieceLength),
+  _knowsTotalLength(true),
+  _ownerRequestGroup(0),
+  _downloadStartTime(0),
+  _downloadStopTime(_downloadStartTime)
 {
-  _signature = signature;
+  SharedHandle<FileEntry> fileEntry(new FileEntry(path, totalLength, 0));
+  _fileEntries.push_back(fileEntry);
 }
 
 void DownloadContext::resetDownloadStartTime()
@@ -94,7 +95,7 @@ DownloadContext::findFileEntryByOffset(off_t offset) const
 
   SharedHandle<FileEntry> obj(new FileEntry());
   obj->setOffset(offset);
-  std::deque<SharedHandle<FileEntry> >::const_iterator i =
+  std::vector<SharedHandle<FileEntry> >::const_iterator i =
     std::upper_bound(_fileEntries.begin(), _fileEntries.end(), obj);
   if(i != _fileEntries.end() && (*i)->getOffset() == offset) {
     return *i;
@@ -103,4 +104,65 @@ DownloadContext::findFileEntryByOffset(off_t offset) const
   }
 }
 
+void DownloadContext::setFilePathWithIndex
+(size_t index, const std::string& path)
+{
+  if(0 < index && index <= _fileEntries.size()) {
+    _fileEntries[index-1]->setPath(path);
+  } else {
+    throw DL_ABORT_EX(StringFormat("No such file with index=%u",
+				   static_cast<unsigned int>(index)).str());
+  }
+}
+
+void DownloadContext::setFileFilter(IntSequence seq)
+{
+  std::deque<int32_t> fileIndexes = seq.flush();
+  std::sort(fileIndexes.begin(), fileIndexes.end());
+  fileIndexes.erase(std::unique(fileIndexes.begin(), fileIndexes.end()),
+		    fileIndexes.end());
+
+  bool selectAll = fileIndexes.empty() || _fileEntries.size() == 1;
+    
+  int32_t index = 1;
+  for(std::vector<SharedHandle<FileEntry> >::const_iterator i =
+	_fileEntries.begin(); i != _fileEntries.end(); ++i, ++index) {
+    (*i)->setRequested
+      (selectAll ||
+       std::binary_search(fileIndexes.begin(), fileIndexes.end(), index));
+  }
+}
+
+void DownloadContext::ensureAttrs()
+{
+  if(_attrs.isNone()) {
+    _attrs = BDE::dict();
+  }
+}
+
+void DownloadContext::setAttribute(const std::string& key, const BDE& value)
+{
+  ensureAttrs();
+  _attrs[key] = value;
+}
+
+BDE& DownloadContext::getAttribute(const std::string& key)
+{
+  ensureAttrs();
+  if(_attrs.containsKey(key)) {
+    return _attrs[key];
+  } else {
+    throw DL_ABORT_EX(StringFormat("No attribute named %s", key.c_str()).str());
+  }
+}
+
+bool DownloadContext::hasAttribute(const std::string& key) const
+{
+  if(_attrs.isNone()) {
+    return false;
+  } else {
+    return _attrs.containsKey(key);
+  }
+}
+
 } // namespace aria2
diff --git a/src/DownloadContext.h b/src/DownloadContext.h
index f1aed08e..ef55b035 100644
--- a/src/DownloadContext.h
+++ b/src/DownloadContext.h
@@ -37,80 +37,194 @@
 
 #include "common.h"
 
+#include <cassert>
 #include <string>
-#include <deque>
+#include <vector>
 
 #include "SharedHandle.h"
 #include "Signature.h"
 #include "TimeA2.h"
+#include "A2STR.h"
+#include "BDE.h"
+#include "IntSequence.h"
 
 namespace aria2 {
 
 class FileEntry;
+class RequestGroup;
 
 class DownloadContext
 {
-protected:
-  std::deque<SharedHandle<FileEntry> > _fileEntries;
+private:
+  std::vector<SharedHandle<FileEntry> > _fileEntries;
 
   std::string _dir;
-private:
+
+  std::vector<std::string> _pieceHashes;
+
+  size_t _pieceLength;
+
+  std::string _pieceHashAlgo;
+
+  std::string _checksum;
+
+  std::string _checksumHashAlgo;
+
+  std::string _basePath;
+
+  bool _knowsTotalLength;
+
+  RequestGroup* _ownerRequestGroup;
+  
+  BDE _attrs;
+
   Time _downloadStartTime;
 
   Time _downloadStopTime;
 
   SharedHandle<Signature> _signature;
+
+  void ensureAttrs();
 public:
   DownloadContext();
 
-  virtual ~DownloadContext();
-
-  enum FILE_MODE {
-    SINGLE,
-    MULTI
-  };
+  // Convenient constructor that creates single file download.
+  DownloadContext(size_t pieceLength,
+		  uint64_t totalLength,
+		  const std::string& path = A2STR::NIL);
 
-  virtual const std::string& getPieceHash(size_t index) const = 0;
+  const std::string& getPieceHash(size_t index) const
+  {
+    if(index < _pieceHashes.size()) {
+      return _pieceHashes[index];
+    } else {
+      return A2STR::NIL;
+    }
+  }
   
-  virtual const std::deque<std::string>& getPieceHashes() const = 0;
+  const std::vector<std::string>& getPieceHashes() const
+  {
+    return _pieceHashes;
+  }
+
+  template<typename InputIterator>
+  void setPieceHashes(InputIterator first, InputIterator last)
+  {
+    _pieceHashes.assign(first, last);
+  }
 
-  virtual uint64_t getTotalLength() const = 0;
+  uint64_t getTotalLength() const
+  {
+    if(_fileEntries.empty()) {
+      return 0;
+    } else {
+      return _fileEntries.back()->getLastOffset();
+    }
+  }
 
-  virtual bool knowsTotalLength() const = 0;
+  bool knowsTotalLength() const { return _knowsTotalLength; }
 
-  virtual FILE_MODE getFileMode() const = 0;
+  void markTotalLengthIsUnknown() { _knowsTotalLength = false; }
 
-  const std::deque<SharedHandle<FileEntry> >& getFileEntries() const
+  const std::vector<SharedHandle<FileEntry> >& getFileEntries() const
   {
     return _fileEntries;
   }
 
-  virtual size_t getPieceLength() const = 0;
+  const SharedHandle<FileEntry>& getFirstFileEntry() const
+  {
+    assert(!_fileEntries.empty());
+    return _fileEntries[0];
+  }
+
+  template<typename InputIterator>
+  void setFileEntries(InputIterator first, InputIterator last)
+  {
+    _fileEntries.assign(first, last);
+  }
+
+  size_t getPieceLength() const { return _pieceLength; }
+
+  void setPieceLength(size_t length) { _pieceLength = length; }
+
+  size_t getNumPieces() const
+  {
+    if(_pieceLength == 0) {
+      return 0;
+    } else {
+      assert(!_fileEntries.empty());
+      return (_fileEntries.back()->getLastOffset()+_pieceLength-1)/_pieceLength;
+    }
+  }
+
+  const std::string& getPieceHashAlgo() const { return _pieceHashAlgo; }
+
+  void setPieceHashAlgo(const std::string& algo)
+  {
+    _pieceHashAlgo = algo;
+  }
+
+  const std::string& getChecksum() const { return _checksum; }
+
+  void setChecksum(const std::string& checksum)
+  {
+    _checksum = checksum;
+  }
+
+  const std::string& getChecksumHashAlgo() const { return _checksumHashAlgo; }
 
-  virtual size_t getNumPieces() const = 0;
+  void setChecksumHashAlgo(const std::string& algo)
+  {
+    _checksumHashAlgo = algo;
+  }
+
+  // The representative path name for this context. It is used as a
+  // part of .aria2 control file. If _basePath is set, returns
+  // _basePath. Otherwise, the first FileEntry's getFilePath() is
+  // returned.
+  const std::string& getBasePath() const
+  {
+    if(_basePath.empty()) {
+      assert(!_fileEntries.empty());
+      return getFirstFileEntry()->getPath();
+    } else {
+      return _basePath;
+    }
+  }
+
+  void setBasePath(const std::string& basePath) { _basePath = basePath; }
+
+  const std::string& getDir() const { return _dir; }
 
-  virtual const std::string& getPieceHashAlgo() const = 0;
+  void setDir(const std::string& dir) { _dir = dir; }
 
-  /**
-   * Returns an actual file path.
-   * If this contains a single file entry, then returns its file path,
-   * for example, "/tmp/downloads/aria2.txt"
-   * If this contains multiple file entries(i,e /tmp/downloads/aria2.txt,
-   * /tmp/downloads/aria2.bin), then returns its base dir path,
-   * for example, "/tmp/downloads"
-   */
-  virtual std::string getActualBasePath() const = 0;
+  SharedHandle<Signature> getSignature() const { return _signature; }
 
-  const std::string& getDir() const
+  void setSignature(const SharedHandle<Signature>& signature)
   {
-    return _dir;
+    _signature = signature;
   }
 
-  void setDir(const std::string& dir);
+  RequestGroup* getOwnerRequestGroup() { return _ownerRequestGroup; }
 
-  SharedHandle<Signature> getSignature() const;
+  void setOwnerRequestGroup(RequestGroup* owner)
+  {
+    _ownerRequestGroup = owner;
+  }
+
+  void setFileFilter(IntSequence seq);
+
+  // Sets file path for spcified index. index starts from 1. The index
+  // is the same used in setFileFilter().  Please note that path is
+  // not the actual file path. The actual file path is
+  // getDir()+"/"+path.
+  void setFilePathWithIndex(size_t index, const std::string& path);
 
-  void setSignature(const SharedHandle<Signature>& signature);
+  void setAttribute(const std::string& key, const BDE& value);
+
+  BDE& getAttribute(const std::string& key);
+
+  bool hasAttribute(const std::string& key) const;
 
   void resetDownloadStartTime();
 
@@ -123,8 +237,6 @@ public:
   SharedHandle<FileEntry> findFileEntryByOffset(off_t offset) const;
 };
 
-typedef SharedHandle<DownloadContext> DownloadContextHandle;
-
 } // namespace aria2
 
 #endif // _D_DOWNLOAD_CONTEXT_H_
diff --git a/src/DownloadEngine.cc b/src/DownloadEngine.cc
index 5808e426..75c507f2 100644
--- a/src/DownloadEngine.cc
+++ b/src/DownloadEngine.cc
@@ -65,14 +65,15 @@
 #include "Command.h"
 #include "FileAllocationEntry.h"
 #include "CheckIntegrityEntry.h"
-
-#include "BtRegistry.h"
-#include "BtContext.h"
-#include "PeerStorage.h"
-#include "PieceStorage.h"
-#include "BtAnnounce.h"
-#include "BtRuntime.h"
 #include "BtProgressInfoFile.h"
+#include "DownloadContext.h"
+#ifdef ENABLE_BITTORRENT
+# include "BtRegistry.h"
+# include "PeerStorage.h"
+# include "PieceStorage.h"
+# include "BtAnnounce.h"
+# include "BtRuntime.h"
+#endif // ENABLE_BITTORRENT
 
 namespace aria2 {
 
diff --git a/src/DownloadEngineFactory.cc b/src/DownloadEngineFactory.cc
index b55b158a..0f83a674 100644
--- a/src/DownloadEngineFactory.cc
+++ b/src/DownloadEngineFactory.cc
@@ -57,6 +57,7 @@
 #include "DownloadResult.h"
 #include "ServerStatMan.h"
 #include "a2io.h"
+#include "DownloadContext.h"
 #ifdef HAVE_EPOLL
 # include "EpollEventPoll.h"
 #endif // HAVE_EPOLL
diff --git a/src/DownloadHandler.cc b/src/DownloadHandler.cc
index 93b901d4..8840a630 100644
--- a/src/DownloadHandler.cc
+++ b/src/DownloadHandler.cc
@@ -37,6 +37,7 @@
 #include "Logger.h"
 #include "RequestGroup.h"
 #include "RequestGroupCriteria.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/DownloadResult.h b/src/DownloadResult.h
index 973095ee..d52c79dc 100644
--- a/src/DownloadResult.h
+++ b/src/DownloadResult.h
@@ -40,7 +40,7 @@
 #include <stdint.h>
 
 #include <string>
-#include <deque>
+#include <vector>
 
 #include "SharedHandle.h"
 #include "FileEntry.h"
@@ -64,7 +64,7 @@ public:
 
   int32_t gid;
  
-  std::deque<SharedHandle<FileEntry> > fileEntries;
+  std::vector<SharedHandle<FileEntry> > fileEntries;
 
   bool inMemoryDownload;
 
@@ -82,7 +82,7 @@ public:
   RESULT result;
 
   DownloadResult(int32_t gid,
-		 const std::deque<SharedHandle<FileEntry> >& fileEntries,
+		 const std::vector<SharedHandle<FileEntry> >& fileEntries,
 		 bool inMemoryDownload,
 		 uint64_t totalLength,
 		 const std::string& uri,
diff --git a/src/FileAllocationCommand.cc b/src/FileAllocationCommand.cc
index db4967a2..1f0eda1a 100644
--- a/src/FileAllocationCommand.cc
+++ b/src/FileAllocationCommand.cc
@@ -42,6 +42,7 @@
 #include "prefs.h"
 #include "Util.h"
 #include "DownloadEngine.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
@@ -78,7 +79,8 @@ bool FileAllocationCommand::handleException(Exception& e)
 {
   _e->_fileAllocationMan->dropPickedEntry();
   logger->error(MSG_FILE_ALLOCATION_FAILURE, e, cuid);
-  logger->error(MSG_DOWNLOAD_NOT_COMPLETE, cuid, _requestGroup->getFilePath().c_str());
+  logger->error(MSG_DOWNLOAD_NOT_COMPLETE, cuid,
+		_requestGroup->getDownloadContext()->getBasePath().c_str());
   return true;
 }
 
diff --git a/src/FileAllocationDispatcherCommand.cc b/src/FileAllocationDispatcherCommand.cc
index ba33aa0b..c86f26cb 100644
--- a/src/FileAllocationDispatcherCommand.cc
+++ b/src/FileAllocationDispatcherCommand.cc
@@ -37,6 +37,7 @@
 #include "FileAllocationCommand.h"
 #include "message.h"
 #include "Logger.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/FileAllocationEntry.cc b/src/FileAllocationEntry.cc
index 6a6cd732..aba0b0c5 100644
--- a/src/FileAllocationEntry.cc
+++ b/src/FileAllocationEntry.cc
@@ -38,6 +38,7 @@
 #include "RequestGroup.h"
 #include "PieceStorage.h"
 #include "DiskAdaptor.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/FileEntry.h b/src/FileEntry.h
index 05ba6067..a40be12e 100644
--- a/src/FileEntry.h
+++ b/src/FileEntry.h
@@ -60,6 +60,7 @@ private:
   bool requested;
   std::deque<SharedHandle<Request> > _requestPool;
   std::deque<SharedHandle<Request> > _inFlightRequests;
+  std::string _contentType;
 public:
   FileEntry():length(0), offset(0), extracted(false), requested(false) {}
 
@@ -128,6 +129,13 @@ public:
   // Inserts _uris and _spentUris into uris.
   void getUris(std::deque<std::string>& uris) const;
 
+  void setContentType(const std::string& contentType)
+  {
+    _contentType = contentType;
+  }
+
+  const std::string& getContentType() const { return _contentType; }
+
   std::string selectUri(const SharedHandle<URISelector>& uriSelector);
 
   // If pooled Request object is available, one of them is removed
diff --git a/src/FillRequestGroupCommand.cc b/src/FillRequestGroupCommand.cc
index 869496b5..1a544b72 100644
--- a/src/FillRequestGroupCommand.cc
+++ b/src/FillRequestGroupCommand.cc
@@ -39,6 +39,7 @@
 #include "RecoverableException.h"
 #include "message.h"
 #include "Logger.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/FtpDownloadCommand.cc b/src/FtpDownloadCommand.cc
index 49a62b5c..d66c0f20 100644
--- a/src/FtpDownloadCommand.cc
+++ b/src/FtpDownloadCommand.cc
@@ -43,6 +43,7 @@
 #include "FtpFinishDownloadCommand.h"
 #include "FtpConnection.h"
 #include "Logger.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/FtpFinishDownloadCommand.cc b/src/FtpFinishDownloadCommand.cc
index bf8af2a2..dbf56edc 100644
--- a/src/FtpFinishDownloadCommand.cc
+++ b/src/FtpFinishDownloadCommand.cc
@@ -47,6 +47,7 @@
 #include "SocketCore.h"
 #include "RequestGroup.h"
 #include "Logger.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/FtpInitiateConnectionCommand.cc b/src/FtpInitiateConnectionCommand.cc
index 7453337a..dcfcde6b 100644
--- a/src/FtpInitiateConnectionCommand.cc
+++ b/src/FtpInitiateConnectionCommand.cc
@@ -50,6 +50,7 @@
 #include "prefs.h"
 #include "HttpConnection.h"
 #include "Socket.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/FtpNegotiationCommand.cc b/src/FtpNegotiationCommand.cc
index cbdea101..555ea605 100644
--- a/src/FtpNegotiationCommand.cc
+++ b/src/FtpNegotiationCommand.cc
@@ -53,7 +53,7 @@
 #include "Option.h"
 #include "Logger.h"
 #include "Segment.h"
-#include "SingleFileDownloadContext.h"
+#include "DownloadContext.h"
 #include "DefaultBtProgressInfoFile.h"
 #include "RequestGroupMan.h"
 #include "DownloadFailureException.h"
@@ -328,17 +328,17 @@ bool FtpNegotiationCommand::sendSize() {
 
 bool FtpNegotiationCommand::onFileSizeDetermined(uint64_t totalLength)
 {
-  SingleFileDownloadContextHandle dctx =
-    dynamic_pointer_cast<SingleFileDownloadContext>(_requestGroup->getDownloadContext());
-  dctx->setTotalLength(totalLength);
   _fileEntry->setLength(totalLength);
-  dctx->setFilename
-    (strconcat(dctx->getDir(), "/", Util::urldecode(req->getFile())));
+  if(getOption()->get(PREF_OUT).empty()) {
+    _fileEntry->setPath
+      (strconcat(getDownloadContext()->getDir(),
+		 "/", Util::urldecode(req->getFile())));
+  }
   _requestGroup->preDownloadProcessing();
   if(e->_requestGroupMan->isSameFileBeingDownloaded(_requestGroup)) {
     throw DOWNLOAD_FAILURE_EXCEPTION
       (StringFormat(EX_DUPLICATE_FILE_DOWNLOAD,
-		    _requestGroup->getFilePath().c_str()).str());
+		    _requestGroup->getFirstFilePath().c_str()).str());
   }
   if(totalLength == 0) {
 
@@ -361,7 +361,7 @@ bool FtpNegotiationCommand::onFileSizeDetermined(uint64_t totalLength)
 
       logger->notice(MSG_DOWNLOAD_ALREADY_COMPLETED,
 		     _requestGroup->getGID(),
-		     _requestGroup->getFilePath().c_str());
+		     _requestGroup->getFirstFilePath().c_str());
 
       poolConnection();
 
@@ -372,7 +372,7 @@ bool FtpNegotiationCommand::onFileSizeDetermined(uint64_t totalLength)
     _requestGroup->initPieceStorage();
     _requestGroup->getPieceStorage()->getDiskAdaptor()->initAndOpenFile();
 
-    if(dctx->knowsTotalLength()) {
+    if(getDownloadContext()->knowsTotalLength()) {
       sequence = SEQ_DOWNLOAD_ALREADY_COMPLETED;
       poolConnection();
       return false;
@@ -400,7 +400,7 @@ bool FtpNegotiationCommand::onFileSizeDetermined(uint64_t totalLength)
       
       logger->notice(MSG_DOWNLOAD_ALREADY_COMPLETED,
 		     _requestGroup->getGID(),
-		     _requestGroup->getFilePath().c_str());
+		     _requestGroup->getFirstFilePath().c_str());
 
       poolConnection();
       
@@ -444,10 +444,7 @@ bool FtpNegotiationCommand::recvSize() {
     // command, resuming and segmented downloading are disabled when the first
     // contacted FTP server doesn't support it.
     if(_requestGroup->getPieceStorage().isNull()) {
-      SingleFileDownloadContextHandle dctx =
-	dynamic_pointer_cast<SingleFileDownloadContext>
-	(_requestGroup->getDownloadContext());
-      dctx->markTotalLengthIsUnknown();
+      getDownloadContext()->markTotalLengthIsUnknown();
       return onFileSizeDetermined(0);
 
     }
diff --git a/src/FtpTunnelRequestCommand.cc b/src/FtpTunnelRequestCommand.cc
index 09a162c5..73e5ed9c 100644
--- a/src/FtpTunnelRequestCommand.cc
+++ b/src/FtpTunnelRequestCommand.cc
@@ -36,6 +36,7 @@
 #include "FtpTunnelResponseCommand.h"
 #include "Request.h"
 #include "Socket.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/FtpTunnelResponseCommand.cc b/src/FtpTunnelResponseCommand.cc
index 293b88c8..0ecb3bd0 100644
--- a/src/FtpTunnelResponseCommand.cc
+++ b/src/FtpTunnelResponseCommand.cc
@@ -39,6 +39,7 @@
 #include "HttpRequest.h"
 #include "Segment.h"
 #include "Socket.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/HandshakeExtensionMessage.cc b/src/HandshakeExtensionMessage.cc
index d276b8d9..370746f4 100644
--- a/src/HandshakeExtensionMessage.cc
+++ b/src/HandshakeExtensionMessage.cc
@@ -34,7 +34,6 @@
 /* copyright --> */
 #include "HandshakeExtensionMessage.h"
 #include "Peer.h"
-#include "BtContext.h"
 #include "Util.h"
 #include "DlAbortEx.h"
 #include "LogFactory.h"
@@ -107,11 +106,6 @@ void HandshakeExtensionMessage::setPeer(const PeerHandle& peer)
   _peer = peer;
 }
 
-void HandshakeExtensionMessage::setBtContext(const BtContextHandle& btContext)
-{
-  _btContext = btContext;
-}
-
 uint8_t HandshakeExtensionMessage::getExtensionMessageID(const std::string& name) const
 {
   std::map<std::string, uint8_t>::const_iterator i = _extensions.find(name);
diff --git a/src/HandshakeExtensionMessage.h b/src/HandshakeExtensionMessage.h
index dc054f52..3c9c7dd9 100644
--- a/src/HandshakeExtensionMessage.h
+++ b/src/HandshakeExtensionMessage.h
@@ -43,7 +43,6 @@
 
 namespace aria2 {
 
-class BtContext;
 class Peer;
 class Logger;
 class HandshakeExtensionMessage;
@@ -57,8 +56,6 @@ private:
 
   std::map<std::string, uint8_t> _extensions;
 
-  SharedHandle<BtContext> _btContext;
-
   SharedHandle<Peer> _peer;
 
   Logger* _logger;
@@ -120,8 +117,6 @@ public:
 
   void setPeer(const SharedHandle<Peer>& peer);
 
-  void setBtContext(const SharedHandle<BtContext>& btContext);
-
   static HandshakeExtensionMessageHandle create(const unsigned char* data,
 						size_t dataLength);
 };
diff --git a/src/HaveEraseCommand.cc b/src/HaveEraseCommand.cc
index 4ad39505..910ee761 100644
--- a/src/HaveEraseCommand.cc
+++ b/src/HaveEraseCommand.cc
@@ -37,6 +37,7 @@
 #include "RequestGroupMan.h"
 #include "PieceStorage.h"
 #include "RequestGroup.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/HttpDownloadCommand.cc b/src/HttpDownloadCommand.cc
index 9819efea..98ada9eb 100644
--- a/src/HttpDownloadCommand.cc
+++ b/src/HttpDownloadCommand.cc
@@ -46,6 +46,7 @@
 #include "HttpResponse.h"
 #include "HttpHeader.h"
 #include "Range.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/HttpInitiateConnectionCommand.cc b/src/HttpInitiateConnectionCommand.cc
index b9552db5..4245403a 100644
--- a/src/HttpInitiateConnectionCommand.cc
+++ b/src/HttpInitiateConnectionCommand.cc
@@ -47,6 +47,7 @@
 #include "message.h"
 #include "prefs.h"
 #include "A2STR.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/HttpProxyRequestCommand.cc b/src/HttpProxyRequestCommand.cc
index 9d0a434b..04e534ee 100644
--- a/src/HttpProxyRequestCommand.cc
+++ b/src/HttpProxyRequestCommand.cc
@@ -36,6 +36,7 @@
 #include "HttpProxyResponseCommand.h"
 #include "Request.h"
 #include "Socket.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/HttpProxyResponseCommand.cc b/src/HttpProxyResponseCommand.cc
index 0054d6d9..be6a58ff 100644
--- a/src/HttpProxyResponseCommand.cc
+++ b/src/HttpProxyResponseCommand.cc
@@ -39,6 +39,7 @@
 #include "HttpRequest.h"
 #include "Segment.h"
 #include "Socket.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/HttpRequest.cc b/src/HttpRequest.cc
index d46f68ac..bac87114 100644
--- a/src/HttpRequest.cc
+++ b/src/HttpRequest.cc
@@ -53,8 +53,7 @@ namespace aria2 {
 
 const std::string HttpRequest::USER_AGENT("aria2");
 
-HttpRequest::HttpRequest():entityLength(0),
-			   _contentEncodingEnabled(true),
+HttpRequest::HttpRequest():_contentEncodingEnabled(true),
 			   userAgent(USER_AGENT)
 {}
 
@@ -83,7 +82,8 @@ off_t HttpRequest::getEndByte() const
     return 0;
   } else {
     if(request->isPipeliningEnabled()) {
-      return _fileEntry->gtoloff(segment->getPosition()+segment->getLength()-1);
+      off_t endByte = _fileEntry->gtoloff(segment->getPosition()+segment->getLength()-1);
+      return std::min(endByte, _fileEntry->getLastOffset()-1);
     } else {
       return 0;
     }
@@ -96,7 +96,8 @@ RangeHandle HttpRequest::getRange() const
   if(segment.isNull()) {
     return SharedHandle<Range>(new Range());
   } else {
-    return SharedHandle<Range>(new Range(getStartByte(), getEndByte(), entityLength));
+    return SharedHandle<Range>(new Range(getStartByte(), getEndByte(),
+					 _fileEntry->getLength()));
   }
 }
 
@@ -107,9 +108,9 @@ bool HttpRequest::isRangeSatisfied(const RangeHandle& range) const
   }
   if((getStartByte() == range->getStartByte()) &&
      ((getEndByte() == 0) ||
-      ((getEndByte() > 0) && (getEndByte() == range->getEndByte()))) &&
-     ((entityLength == 0) ||
-      ((entityLength > 0) && (entityLength == range->getEntityLength())))) {
+      (getEndByte() == range->getEndByte())) &&
+     ((_fileEntry->getLength() == 0) ||
+      (_fileEntry->getLength() == range->getEntityLength()))) {
     return true;
   } else {
     return false;
diff --git a/src/HttpRequest.h b/src/HttpRequest.h
index 9ec32171..def1ddd6 100644
--- a/src/HttpRequest.h
+++ b/src/HttpRequest.h
@@ -37,6 +37,7 @@
 
 #include "common.h"
 
+#include <cassert>
 #include <string>
 #include <deque>
 
@@ -64,8 +65,6 @@ private:
 
   SharedHandle<Segment> segment;
 
-  uint64_t entityLength;
-
   bool _contentEncodingEnabled;
 
   std::string userAgent;
@@ -97,17 +96,10 @@ public:
 
   void setRequest(const SharedHandle<Request>& request);
 
-  /**
-   * entityLength is used in isRangeSatisfied() method.
-   */
-  void setEntityLength(uint64_t entityLength)
-  {
-    this->entityLength = entityLength;
-  }
-
   uint64_t getEntityLength() const
   {
-    return entityLength;
+    assert(!_fileEntry.isNull());
+    return _fileEntry->getLength();
   }
 
   const std::string& getHost() const
diff --git a/src/HttpRequestCommand.cc b/src/HttpRequestCommand.cc
index d95e616b..961e8155 100644
--- a/src/HttpRequestCommand.cc
+++ b/src/HttpRequestCommand.cc
@@ -52,6 +52,7 @@
 #include "CookieStorage.h"
 #include "AuthConfigFactory.h"
 #include "AuthConfig.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
@@ -89,7 +90,6 @@ createHttpRequest(const SharedHandle<Request>& req,
   httpRequest->setRequest(req);
   httpRequest->setFileEntry(fileEntry);
   httpRequest->setSegment(segment);
-  httpRequest->setEntityLength(fileEntry->getLength());
   httpRequest->addHeader(option->get(PREF_HEADER));
   httpRequest->setCookieStorage(cookieStorage);
   httpRequest->setAuthConfigFactory(authConfigFactory);
diff --git a/src/HttpResponseCommand.cc b/src/HttpResponseCommand.cc
index 30de2641..ece2606a 100644
--- a/src/HttpResponseCommand.cc
+++ b/src/HttpResponseCommand.cc
@@ -34,7 +34,7 @@
 /* copyright --> */
 #include "HttpResponseCommand.h"
 #include "DownloadEngine.h"
-#include "SingleFileDownloadContext.h"
+#include "DownloadContext.h"
 #include "FileEntry.h"
 #include "RequestGroup.h"
 #include "ServerHost.h"
@@ -136,18 +136,20 @@ bool HttpResponseCommand::executeInternal()
   }
   if(_requestGroup->getPieceStorage().isNull()) {
     uint64_t totalLength = httpResponse->getEntityLength();
-    SingleFileDownloadContextHandle dctx =
-      dynamic_pointer_cast<SingleFileDownloadContext>(_requestGroup->getDownloadContext());
-    dctx->setTotalLength(totalLength);
     _fileEntry->setLength(totalLength);
-    dctx->setFilename
-      (strconcat(dctx->getDir(), "/", httpResponse->determinFilename()));
-    dctx->setContentType(httpResponse->getContentType());
+    // We assume that in this context
+    // DownloadContext::getFileEntries().size() == 1
+    if(getOption()->get(PREF_OUT).empty()) {
+      _fileEntry->setPath
+	(strconcat(getDownloadContext()->getDir(),
+		   "/", httpResponse->determinFilename()));
+    }
+    _fileEntry->setContentType(httpResponse->getContentType());
     _requestGroup->preDownloadProcessing();
     if(e->_requestGroupMan->isSameFileBeingDownloaded(_requestGroup)) {
       throw DOWNLOAD_FAILURE_EXCEPTION
 	(StringFormat(EX_DUPLICATE_FILE_DOWNLOAD,
-		      _requestGroup->getFilePath().c_str()).str());
+		      _requestGroup->getFirstFilePath().c_str()).str());
     }
     // update last modified time
     updateLastModifiedTime(httpResponse->getLastModifiedTime());
@@ -156,13 +158,13 @@ bool HttpResponseCommand::executeInternal()
     // assume we can do segmented downloading
     if(totalLength == 0 || shouldInflateContentEncoding(httpResponse)) {
       // we ignore content-length when inflate is required
-      dctx->setTotalLength(0);
+      _fileEntry->setLength(0);
       if(req->getMethod() == Request::METHOD_GET &&
 	 (totalLength != 0 ||
 	  !httpResponse->getHttpHeader()->defined(HttpHeader::CONTENT_LENGTH))){
-	// dctx->knowsTotalLength() == true only when server says the
-	// size of file is 0 explicitly.
-	dctx->markTotalLengthIsUnknown();
+	// DownloadContext::knowsTotalLength() == true only when
+	// server says the size of file is 0 explicitly.
+	getDownloadContext()->markTotalLengthIsUnknown();
       }
       return handleOtherEncoding(httpResponse);
     } else {
@@ -241,7 +243,7 @@ bool HttpResponseCommand::handleDefaultEncoding(const HttpResponseHandle& httpRe
 
     logger->notice(MSG_DOWNLOAD_ALREADY_COMPLETED,
 		   _requestGroup->getGID(),
-		   _requestGroup->getFilePath().c_str());
+		   _requestGroup->getFirstFilePath().c_str());
 
     return true;
   }
@@ -249,7 +251,7 @@ bool HttpResponseCommand::handleDefaultEncoding(const HttpResponseHandle& httpRe
   DownloadCommand* command = 0;
   try {
     _requestGroup->loadAndOpenFile(infoFile);
-    File file(_requestGroup->getFilePath());
+    File file(_requestGroup->getFirstFilePath());
 
     SegmentHandle segment = _requestGroup->getSegmentMan()->getSegment(cuid, 0);
     // pipelining requires implicit range specified. But the request for
@@ -335,7 +337,7 @@ bool HttpResponseCommand::handleOtherEncoding(const HttpResponseHandle& httpResp
 
     logger->notice(MSG_DOWNLOAD_ALREADY_COMPLETED,
 		   _requestGroup->getGID(),
-		   _requestGroup->getFilePath().c_str());
+		   _requestGroup->getFirstFilePath().c_str());
 
     poolConnection();
     return true;
diff --git a/src/HttpServerBodyCommand.cc b/src/HttpServerBodyCommand.cc
index afbf601d..c40efde1 100644
--- a/src/HttpServerBodyCommand.cc
+++ b/src/HttpServerBodyCommand.cc
@@ -49,6 +49,7 @@
 #include "XmlRpcMethod.h"
 #include "XmlRpcMethodFactory.h"
 #include "XmlRpcResponse.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/HttpServerCommand.cc b/src/HttpServerCommand.cc
index 55f32427..38b9bdee 100644
--- a/src/HttpServerCommand.cc
+++ b/src/HttpServerCommand.cc
@@ -46,6 +46,7 @@
 #include "prefs.h"
 #include "Option.h"
 #include "Util.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/HttpSkipResponseCommand.cc b/src/HttpSkipResponseCommand.cc
index b9edb717..ff1bf174 100644
--- a/src/HttpSkipResponseCommand.cc
+++ b/src/HttpSkipResponseCommand.cc
@@ -53,6 +53,7 @@
 #include "CookieStorage.h"
 #include "AuthConfigFactory.h"
 #include "AuthConfig.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/InitiateConnectionCommandFactory.cc b/src/InitiateConnectionCommandFactory.cc
index 2ad3dbda..450f6d46 100644
--- a/src/InitiateConnectionCommandFactory.cc
+++ b/src/InitiateConnectionCommandFactory.cc
@@ -43,6 +43,7 @@
 #include "Option.h"
 #include "prefs.h"
 #include "SocketCore.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/InitiatorMSEHandshakeCommand.cc b/src/InitiatorMSEHandshakeCommand.cc
index b29fe38c..7afeab6e 100644
--- a/src/InitiatorMSEHandshakeCommand.cc
+++ b/src/InitiatorMSEHandshakeCommand.cc
@@ -43,7 +43,6 @@
 #include "Logger.h"
 #include "Peer.h"
 #include "PeerConnection.h"
-#include "BtContext.h"
 #include "BtRuntime.h"
 #include "PeerStorage.h"
 #include "PieceStorage.h"
@@ -52,6 +51,8 @@
 #include "ARC4Encryptor.h"
 #include "ARC4Decryptor.h"
 #include "RequestGroup.h"
+#include "DownloadContext.h"
+#include "bittorrent_helper.h"
 
 namespace aria2 {
 
@@ -60,13 +61,11 @@ InitiatorMSEHandshakeCommand::InitiatorMSEHandshakeCommand
  RequestGroup* requestGroup,
  const SharedHandle<Peer>& p,
  DownloadEngine* e,
- const SharedHandle<BtContext>& btContext,
  const SharedHandle<BtRuntime>& btRuntime,
  const SharedHandle<SocketCore>& s):
 
   PeerAbstractCommand(cuid, p, e, s),
   _requestGroup(requestGroup),
-  _btContext(btContext),
   _btRuntime(btRuntime),
   _sequence(INITIATOR_SEND_KEY),
   _mseHandshake(new MSEHandshake(cuid, socket, getOption().get()))
@@ -114,7 +113,8 @@ bool InitiatorMSEHandshakeCommand::executeInternal() {
     break;
   case INITIATOR_WAIT_KEY: {
     if(_mseHandshake->receivePublicKey()) {
-      _mseHandshake->initCipher(_btContext->getInfoHash());
+      _mseHandshake->initCipher
+	(bittorrent::getInfoHash(_requestGroup->getDownloadContext()));;
       if(_mseHandshake->sendInitiatorStep2()) {
 	_sequence = INITIATOR_FIND_VC_MARKER;
       } else {
@@ -151,11 +151,11 @@ bool InitiatorMSEHandshakeCommand::executeInternal() {
 					 _mseHandshake->getDecryptor());
       }
       PeerInteractionCommand* c =
-	  new PeerInteractionCommand(cuid, _requestGroup, peer, e, _btContext,
-				     _btRuntime, _pieceStorage,
-				     socket,
-				     PeerInteractionCommand::INITIATOR_SEND_HANDSHAKE,
-				     peerConnection);
+	  new PeerInteractionCommand
+	(cuid, _requestGroup, peer, e, _btRuntime, _pieceStorage,
+	 socket,
+	 PeerInteractionCommand::INITIATOR_SEND_HANDSHAKE,
+	 peerConnection);
       c->setPeerStorage(_peerStorage);
       e->commands.push_back(c);
       return true;
@@ -176,7 +176,7 @@ bool InitiatorMSEHandshakeCommand::prepareForNextPeer(time_t wait)
       peer->usedBy(e->newCUID());
       PeerInitiateConnectionCommand* command =
 	new PeerInitiateConnectionCommand(peer->usedBy(), _requestGroup, peer,
-					  e, _btContext, _btRuntime);
+					  e, _btRuntime);
       command->setPeerStorage(_peerStorage);
       command->setPieceStorage(_pieceStorage);
       e->commands.push_back(command);
@@ -187,7 +187,7 @@ bool InitiatorMSEHandshakeCommand::prepareForNextPeer(time_t wait)
     logger->info("CUID#%d - Retry using legacy BitTorrent handshake.", cuid);
     PeerInitiateConnectionCommand* command =
       new PeerInitiateConnectionCommand(cuid, _requestGroup, peer, e,
-					_btContext, _btRuntime, false);
+					_btRuntime, false);
     command->setPeerStorage(_peerStorage);
     command->setPieceStorage(_pieceStorage);
     e->commands.push_back(command);
diff --git a/src/InitiatorMSEHandshakeCommand.h b/src/InitiatorMSEHandshakeCommand.h
index 46cbedf0..996a72e9 100644
--- a/src/InitiatorMSEHandshakeCommand.h
+++ b/src/InitiatorMSEHandshakeCommand.h
@@ -40,7 +40,6 @@
 namespace aria2 {
 
 class RequestGroup;
-class BtContext;
 class PeerStorage;
 class PieceStorage;
 class BtRuntime;
@@ -61,8 +60,6 @@ public:
 private:
   RequestGroup* _requestGroup;
 
-  SharedHandle<BtContext> _btContext;
-
   SharedHandle<PeerStorage> _peerStorage;
 
   SharedHandle<PieceStorage> _pieceStorage;
@@ -79,13 +76,13 @@ protected:
   virtual void onAbort();
   virtual bool exitBeforeExecute();
 public:
-  InitiatorMSEHandshakeCommand(int32_t cuid,
-			       RequestGroup* requestGroup,
-			       const SharedHandle<Peer>& peer,
-			       DownloadEngine* e,
-			       const SharedHandle<BtContext>& btContext,
-			       const SharedHandle<BtRuntime>& btRuntime,
-			       const SharedHandle<SocketCore>& s);
+  InitiatorMSEHandshakeCommand
+    (int32_t cuid,
+     RequestGroup* requestGroup,
+     const SharedHandle<Peer>& peer,
+     DownloadEngine* e,
+     const SharedHandle<BtRuntime>& btRuntime,
+     const SharedHandle<SocketCore>& s);
 
   virtual ~InitiatorMSEHandshakeCommand();
 
diff --git a/src/IteratableChecksumValidator.cc b/src/IteratableChecksumValidator.cc
index b250af4d..a3be0a21 100644
--- a/src/IteratableChecksumValidator.cc
+++ b/src/IteratableChecksumValidator.cc
@@ -38,7 +38,6 @@
 
 #include "Util.h"
 #include "message.h"
-#include "SingleFileDownloadContext.h"
 #include "PieceStorage.h"
 #include "messageDigest.h"
 #include "LogFactory.h"
@@ -46,14 +45,16 @@
 #include "DiskAdaptor.h"
 #include "FileEntry.h"
 #include "BitfieldMan.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
 #define BUFSIZE (256*1024)
 #define ALIGNMENT 512
 
-IteratableChecksumValidator::IteratableChecksumValidator(const SingleFileDownloadContextHandle& dctx,
-							 const PieceStorageHandle& pieceStorage):
+IteratableChecksumValidator::IteratableChecksumValidator
+(const SharedHandle<DownloadContext>& dctx,
+ const PieceStorageHandle& pieceStorage):
   _dctx(dctx),
   _pieceStorage(pieceStorage),
   _currentOffset(0),
diff --git a/src/IteratableChecksumValidator.h b/src/IteratableChecksumValidator.h
index 2a8997a8..62112e95 100644
--- a/src/IteratableChecksumValidator.h
+++ b/src/IteratableChecksumValidator.h
@@ -39,7 +39,7 @@
 
 namespace aria2 {
 
-class SingleFileDownloadContext;
+class DownloadContext;
 class PieceStorage;
 class Logger;
 class MessageDigestContext;
@@ -47,7 +47,7 @@ class MessageDigestContext;
 class IteratableChecksumValidator:public IteratableValidator
 {
 private:
-  SharedHandle<SingleFileDownloadContext> _dctx;
+  SharedHandle<DownloadContext> _dctx;
 
   SharedHandle<PieceStorage> _pieceStorage;
 
@@ -60,7 +60,7 @@ private:
   unsigned char* _buffer;
 
 public:
-  IteratableChecksumValidator(const SharedHandle<SingleFileDownloadContext>& dctx,
+  IteratableChecksumValidator(const SharedHandle<DownloadContext>& dctx,
 			      const SharedHandle<PieceStorage>& pieceStorage);
 
   virtual ~IteratableChecksumValidator();
diff --git a/src/IteratableChunkChecksumValidator.cc b/src/IteratableChunkChecksumValidator.cc
index bb3f2fcb..b58ab90d 100644
--- a/src/IteratableChunkChecksumValidator.cc
+++ b/src/IteratableChunkChecksumValidator.cc
@@ -58,7 +58,7 @@ namespace aria2 {
 #define ALIGNMENT 512
 
 IteratableChunkChecksumValidator::
-IteratableChunkChecksumValidator(const DownloadContextHandle& dctx,
+IteratableChunkChecksumValidator(const SharedHandle<DownloadContext>& dctx,
 				 const PieceStorageHandle& pieceStorage):
   _dctx(dctx),
   _pieceStorage(pieceStorage),
@@ -153,7 +153,7 @@ std::string IteratableChunkChecksumValidator::digest(off_t offset, size_t length
 							 curoffset);
     if(r == 0 || r < static_cast<size_t>(woffset)) {
       throw DL_ABORT_EX
-	(StringFormat(EX_FILE_READ, _dctx->getActualBasePath().c_str(),
+	(StringFormat(EX_FILE_READ, _dctx->getBasePath().c_str(),
 		      strerror(errno)).str());
     }
     size_t wlength;
diff --git a/src/MSEHandshake.cc b/src/MSEHandshake.cc
index 70ce2ef7..760002bc 100644
--- a/src/MSEHandshake.cc
+++ b/src/MSEHandshake.cc
@@ -50,10 +50,11 @@
 #include "MessageDigestHelper.h"
 #include "SimpleRandomizer.h"
 #include "Util.h"
-#include "BtContext.h"
+#include "DownloadContext.h"
 #include "prefs.h"
 #include "Option.h"
 #include "StringFormat.h"
+#include "bittorrent_helper.h"
 
 namespace aria2 {
 
@@ -435,7 +436,7 @@ bool MSEHandshake::findReceiverHashMarker()
 }
 
 bool MSEHandshake::receiveReceiverHashAndPadCLength
-(const std::deque<SharedHandle<BtContext> >& btContexts)
+(const std::deque<SharedHandle<DownloadContext> >& downloadContexts)
 {
   size_t r = 20+VC_LENGTH+CRYPTO_BITFIELD_LENGTH+2/*PadC length*/-_rbufLength;
   if(r > receiveNBytes(r)) {
@@ -444,22 +445,23 @@ bool MSEHandshake::receiveReceiverHashAndPadCLength
   // resolve info hash
   // pointing to the position of HASH('req2', SKEY) xor HASH('req3', S)
   unsigned char* rbufptr = _rbuf;
-  SharedHandle<BtContext> btContext;
-  for(std::deque<SharedHandle<BtContext> >::const_iterator i = btContexts.begin();
-      i != btContexts.end(); ++i) {
+  SharedHandle<DownloadContext> downloadContext;
+  for(std::deque<SharedHandle<DownloadContext> >::const_iterator i =
+	downloadContexts.begin(); i != downloadContexts.end(); ++i) {
     unsigned char md[20];
-    createReq23Hash(md, (*i)->getInfoHash());
+    const BDE& torrentAttrs = (*i)->getAttribute(bittorrent::BITTORRENT);
+    createReq23Hash(md, torrentAttrs[bittorrent::INFO_HASH].uc());
     if(memcmp(md, rbufptr, sizeof(md)) == 0) {
-      _logger->debug("CUID#%d - info hash found: %s", _cuid, (*i)->getInfoHashAsString().c_str());
-      btContext = *i;
+      _logger->debug("CUID#%d - info hash found: %s", _cuid,
+		     Util::toHex(torrentAttrs[bittorrent::INFO_HASH].s()).c_str());
+      downloadContext = *i;
       break;
     }
   }
-  if(btContext.isNull()) {
+  if(downloadContext.isNull()) {
     throw DL_ABORT_EX("Unknown info hash.");
   }
-  initCipher(btContext->getInfoHash());
-
+  initCipher(bittorrent::getInfoHash(downloadContext));
   // decrypt VC
   rbufptr += 20;
   verifyVC(rbufptr);
diff --git a/src/MSEHandshake.h b/src/MSEHandshake.h
index f2ceb3a7..14ef0ad3 100644
--- a/src/MSEHandshake.h
+++ b/src/MSEHandshake.h
@@ -51,7 +51,7 @@ class SocketCore;
 class DHKeyExchange;
 class ARC4Encryptor;
 class ARC4Decryptor;
-class BtContext;
+class DownloadContext;
 
 class MSEHandshake {
 public:
@@ -158,7 +158,7 @@ public:
   bool findReceiverHashMarker();
 
   bool receiveReceiverHashAndPadCLength
-  (const std::deque<SharedHandle<BtContext> >& btContexts);
+  (const std::deque<SharedHandle<DownloadContext> >& downloadContexts);
 
   bool receiveReceiverIALength();
 
diff --git a/src/Makefile.am b/src/Makefile.am
index 5951269f..235befee 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -152,7 +152,6 @@ SRCS =  Socket.h\
 	ByteArrayDiskWriterFactory.cc ByteArrayDiskWriterFactory.h\
 	ServerHost.cc ServerHost.h\
 	DownloadContext.cc DownloadContext.h\
-	SingleFileDownloadContext.cc SingleFileDownloadContext.h\
 	TimedHaltCommand.cc TimedHaltCommand.h\
 	CUIDCounter.h\
 	DNSCache.h\
@@ -294,8 +293,6 @@ SRCS += PeerMessageUtil.cc PeerMessageUtil.h\
 	PeerListProcessor.h\
 	AnnounceTier.h\
 	AnnounceList.h AnnounceList.cc\
-	BtContext.h\
-	DefaultBtContext.cc DefaultBtContext.h\
 	PeerStorage.h\
 	DefaultPeerStorage.cc DefaultPeerStorage.h\
 	BtAnnounce.cc BtAnnounce.h\
@@ -436,7 +433,8 @@ SRCS += PeerMessageUtil.cc PeerMessageUtil.h\
 	RangeBtMessageValidator.h\
 	IndexBtMessageValidator.h\
 	ExtensionMessageRegistry.h\
-	bencode.cc bencode.h
+	bencode.cc bencode.h\
+	bittorrent_helper.cc bittorrent_helper.h
 endif # ENABLE_BITTORRENT
 
 if ENABLE_METALINK
diff --git a/src/Makefile.in b/src/Makefile.in
index f46e2465..09e34803 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -89,8 +89,6 @@ bin_PROGRAMS = aria2c$(EXEEXT)
 @ENABLE_BITTORRENT_TRUE@	PeerListProcessor.h\
 @ENABLE_BITTORRENT_TRUE@	AnnounceTier.h\
 @ENABLE_BITTORRENT_TRUE@	AnnounceList.h AnnounceList.cc\
-@ENABLE_BITTORRENT_TRUE@	BtContext.h\
-@ENABLE_BITTORRENT_TRUE@	DefaultBtContext.cc DefaultBtContext.h\
 @ENABLE_BITTORRENT_TRUE@	PeerStorage.h\
 @ENABLE_BITTORRENT_TRUE@	DefaultPeerStorage.cc DefaultPeerStorage.h\
 @ENABLE_BITTORRENT_TRUE@	BtAnnounce.cc BtAnnounce.h\
@@ -231,7 +229,8 @@ bin_PROGRAMS = aria2c$(EXEEXT)
 @ENABLE_BITTORRENT_TRUE@	RangeBtMessageValidator.h\
 @ENABLE_BITTORRENT_TRUE@	IndexBtMessageValidator.h\
 @ENABLE_BITTORRENT_TRUE@	ExtensionMessageRegistry.h\
-@ENABLE_BITTORRENT_TRUE@	bencode.cc bencode.h
+@ENABLE_BITTORRENT_TRUE@	bencode.cc bencode.h\
+@ENABLE_BITTORRENT_TRUE@	bittorrent_helper.cc bittorrent_helper.h
 
 @ENABLE_METALINK_TRUE@am__append_14 = Metalinker.cc Metalinker.h\
 @ENABLE_METALINK_TRUE@	MetalinkEntry.cc MetalinkEntry.h\
@@ -400,11 +399,10 @@ am__libaria2c_a_SOURCES_DIST = Socket.h SocketCore.cc SocketCore.h \
 	PeerConnection.cc PeerConnection.h ByteArrayDiskWriter.cc \
 	ByteArrayDiskWriter.h ByteArrayDiskWriterFactory.cc \
 	ByteArrayDiskWriterFactory.h ServerHost.cc ServerHost.h \
-	DownloadContext.cc DownloadContext.h \
-	SingleFileDownloadContext.cc SingleFileDownloadContext.h \
-	TimedHaltCommand.cc TimedHaltCommand.h CUIDCounter.h \
-	DNSCache.h DownloadResult.h Sequence.h IntSequence.h \
-	PostDownloadHandler.h PreDownloadHandler.h SingletonHolder.h \
+	DownloadContext.cc DownloadContext.h TimedHaltCommand.cc \
+	TimedHaltCommand.h CUIDCounter.h DNSCache.h DownloadResult.h \
+	Sequence.h IntSequence.h PostDownloadHandler.h \
+	PreDownloadHandler.h SingletonHolder.h \
 	TrueRequestGroupCriteria.h a2algo.h a2functional.h a2io.h \
 	a2netcompat.h a2time.h array_fun.h help_tags.h prefs.cc \
 	prefs.h usage_text.h ProtocolDetector.cc ProtocolDetector.h \
@@ -466,8 +464,7 @@ am__libaria2c_a_SOURCES_DIST = Socket.h SocketCore.cc SocketCore.h \
 	TimeSeedCriteria.h ShareRatioSeedCriteria.h \
 	UnionSeedCriteria.h SeedCheckCommand.cc SeedCheckCommand.h \
 	PeerListProcessor.h AnnounceTier.h AnnounceList.h \
-	AnnounceList.cc BtContext.h DefaultBtContext.cc \
-	DefaultBtContext.h PeerStorage.h DefaultPeerStorage.cc \
+	AnnounceList.cc PeerStorage.h DefaultPeerStorage.cc \
 	DefaultPeerStorage.h BtAnnounce.cc BtAnnounce.h \
 	DefaultBtAnnounce.cc DefaultBtAnnounce.h BtRuntime.h \
 	BtMessage.h AbstractBtMessage.cc AbstractBtMessage.h \
@@ -564,9 +561,9 @@ am__libaria2c_a_SOURCES_DIST = Socket.h SocketCore.cc SocketCore.h \
 	IndexBtMessage.cc IndexBtMessage.h ZeroBtMessage.cc \
 	ZeroBtMessage.h RangeBtMessageValidator.h \
 	IndexBtMessageValidator.h ExtensionMessageRegistry.h \
-	bencode.cc bencode.h Metalinker.cc Metalinker.h \
-	MetalinkEntry.cc MetalinkEntry.h MetalinkResource.cc \
-	MetalinkResource.h MetalinkProcessor.h \
+	bencode.cc bencode.h bittorrent_helper.cc bittorrent_helper.h \
+	Metalinker.cc Metalinker.h MetalinkEntry.cc MetalinkEntry.h \
+	MetalinkResource.cc MetalinkResource.h MetalinkProcessor.h \
 	MetalinkParserController.cc MetalinkParserController.h \
 	MetalinkParserStateMachine.cc MetalinkParserStateMachine.h \
 	MetalinkParserState.h InitialMetalinkParserState.cc \
@@ -638,7 +635,6 @@ am__objects_6 =
 @ENABLE_BITTORRENT_TRUE@	PeerChokeCommand.$(OBJEXT) \
 @ENABLE_BITTORRENT_TRUE@	SeedCheckCommand.$(OBJEXT) \
 @ENABLE_BITTORRENT_TRUE@	AnnounceList.$(OBJEXT) \
-@ENABLE_BITTORRENT_TRUE@	DefaultBtContext.$(OBJEXT) \
 @ENABLE_BITTORRENT_TRUE@	DefaultPeerStorage.$(OBJEXT) \
 @ENABLE_BITTORRENT_TRUE@	BtAnnounce.$(OBJEXT) \
 @ENABLE_BITTORRENT_TRUE@	DefaultBtAnnounce.$(OBJEXT) \
@@ -734,7 +730,8 @@ am__objects_6 =
 @ENABLE_BITTORRENT_TRUE@	RangeBtMessage.$(OBJEXT) \
 @ENABLE_BITTORRENT_TRUE@	IndexBtMessage.$(OBJEXT) \
 @ENABLE_BITTORRENT_TRUE@	ZeroBtMessage.$(OBJEXT) \
-@ENABLE_BITTORRENT_TRUE@	bencode.$(OBJEXT)
+@ENABLE_BITTORRENT_TRUE@	bencode.$(OBJEXT) \
+@ENABLE_BITTORRENT_TRUE@	bittorrent_helper.$(OBJEXT)
 @ENABLE_METALINK_TRUE@am__objects_14 = Metalinker.$(OBJEXT) \
 @ENABLE_METALINK_TRUE@	MetalinkEntry.$(OBJEXT) \
 @ENABLE_METALINK_TRUE@	MetalinkResource.$(OBJEXT) \
@@ -833,10 +830,9 @@ am__objects_26 = SocketCore.$(OBJEXT) Command.$(OBJEXT) \
 	MultiFileAllocationIterator.$(OBJEXT) PeerConnection.$(OBJEXT) \
 	ByteArrayDiskWriter.$(OBJEXT) \
 	ByteArrayDiskWriterFactory.$(OBJEXT) ServerHost.$(OBJEXT) \
-	DownloadContext.$(OBJEXT) SingleFileDownloadContext.$(OBJEXT) \
-	TimedHaltCommand.$(OBJEXT) prefs.$(OBJEXT) \
-	ProtocolDetector.$(OBJEXT) StringFormat.$(OBJEXT) \
-	HttpSkipResponseCommand.$(OBJEXT) \
+	DownloadContext.$(OBJEXT) TimedHaltCommand.$(OBJEXT) \
+	prefs.$(OBJEXT) ProtocolDetector.$(OBJEXT) \
+	StringFormat.$(OBJEXT) HttpSkipResponseCommand.$(OBJEXT) \
 	InitiateConnectionCommand.$(OBJEXT) \
 	FtpFinishDownloadCommand.$(OBJEXT) A2STR.$(OBJEXT) \
 	RarestPieceSelector.$(OBJEXT) ChunkedDecoder.$(OBJEXT) \
@@ -1157,11 +1153,10 @@ SRCS = Socket.h SocketCore.cc SocketCore.h BinaryStream.h Command.cc \
 	PeerConnection.cc PeerConnection.h ByteArrayDiskWriter.cc \
 	ByteArrayDiskWriter.h ByteArrayDiskWriterFactory.cc \
 	ByteArrayDiskWriterFactory.h ServerHost.cc ServerHost.h \
-	DownloadContext.cc DownloadContext.h \
-	SingleFileDownloadContext.cc SingleFileDownloadContext.h \
-	TimedHaltCommand.cc TimedHaltCommand.h CUIDCounter.h \
-	DNSCache.h DownloadResult.h Sequence.h IntSequence.h \
-	PostDownloadHandler.h PreDownloadHandler.h SingletonHolder.h \
+	DownloadContext.cc DownloadContext.h TimedHaltCommand.cc \
+	TimedHaltCommand.h CUIDCounter.h DNSCache.h DownloadResult.h \
+	Sequence.h IntSequence.h PostDownloadHandler.h \
+	PreDownloadHandler.h SingletonHolder.h \
 	TrueRequestGroupCriteria.h a2algo.h a2functional.h a2io.h \
 	a2netcompat.h a2time.h array_fun.h help_tags.h prefs.cc \
 	prefs.h usage_text.h ProtocolDetector.cc ProtocolDetector.h \
@@ -1393,7 +1388,6 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/DHTUtil.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/DefaultAuthResolver.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/DefaultBtAnnounce.Po@am__quote@
-@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/DefaultBtContext.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/DefaultBtInteractive.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/DefaultBtMessageDispatcher.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/DefaultBtMessageFactory.Po@am__quote@
@@ -1541,7 +1535,6 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/SimpleLogger.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/SimpleRandomizer.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/SingleFileAllocationIterator.Po@am__quote@
-@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/SingleFileDownloadContext.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/SizeMetalinkParserState.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/SkipTagMetalinkParserState.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/SleepCommand.Po@am__quote@
@@ -1578,6 +1571,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/ZeroBtMessage.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/asctime_r.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/bencode.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/bittorrent_helper.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/download_helper.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/gai_strerror.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/getaddrinfo.Po@am__quote@
diff --git a/src/Metalink2RequestGroup.cc b/src/Metalink2RequestGroup.cc
index e8874c8f..1b9a36a4 100644
--- a/src/Metalink2RequestGroup.cc
+++ b/src/Metalink2RequestGroup.cc
@@ -43,7 +43,7 @@
 #include "prefs.h"
 #include "Util.h"
 #include "message.h"
-#include "SingleFileDownloadContext.h"
+#include "DownloadContext.h"
 #include "MetalinkHelper.h"
 #include "BinaryStream.h"
 #include "MemoryBufferPreDownloadHandler.h"
@@ -170,10 +170,11 @@ Metalink2RequestGroup::createRequestGroup
       std::deque<std::string> uris;
       uris.push_back((*itr)->url);
       torrentRg.reset(new RequestGroup(option, uris));
-      SharedHandle<SingleFileDownloadContext> dctx
-	(new SingleFileDownloadContext(option->getAsInt(PREF_SEGMENT_SIZE),
-				       0,
-				       A2STR::NIL));
+      SharedHandle<DownloadContext> dctx
+	(new DownloadContext(option->getAsInt(PREF_SEGMENT_SIZE),
+			     0,
+			     A2STR::NIL));
+      // Since torrent is downloaded in memory, setting dir has no effect.
       //dctx->setDir(_option->get(PREF_DIR));
       torrentRg->setDownloadContext(dctx);
       torrentRg->clearPreDowloadHandler();
@@ -208,11 +209,10 @@ Metalink2RequestGroup::createRequestGroup
 #else
     pieceLength = option->getAsInt(PREF_SEGMENT_SIZE);
 #endif // ENABLE_MESSAGE_DIGEST
-    SharedHandle<SingleFileDownloadContext> dctx
-      (new SingleFileDownloadContext
+    SharedHandle<DownloadContext> dctx
+      (new DownloadContext
        (pieceLength,
 	entry->getLength(),
-	A2STR::NIL,
 	strconcat(option->get(PREF_DIR), "/", entry->file->getPath())));
     dctx->setDir(option->get(PREF_DIR));
 #ifdef ENABLE_MESSAGE_DIGEST
@@ -222,7 +222,8 @@ Metalink2RequestGroup::createRequestGroup
 	dctx->setChecksumHashAlgo(entry->checksum->getAlgo());
       }
     } else {
-      dctx->setPieceHashes(entry->chunkChecksum->getChecksums());
+      dctx->setPieceHashes(entry->chunkChecksum->getChecksums().begin(),
+			   entry->chunkChecksum->getChecksums().end());
       dctx->setPieceHashAlgo(entry->chunkChecksum->getAlgo());
     }
 #endif // ENABLE_MESSAGE_DIGEST
diff --git a/src/MetalinkPostDownloadHandler.cc b/src/MetalinkPostDownloadHandler.cc
index 7623f1e8..038a3687 100644
--- a/src/MetalinkPostDownloadHandler.cc
+++ b/src/MetalinkPostDownloadHandler.cc
@@ -62,7 +62,7 @@ void MetalinkPostDownloadHandler::getNextRequestGroups
  RequestGroup* requestGroup)
 {
   _logger->debug("Generating RequestGroups for Metalink file %s",
-		 requestGroup->getFilePath().c_str());
+		 requestGroup->getFirstFilePath().c_str());
   SharedHandle<DiskAdaptor> diskAdaptor = requestGroup->getPieceStorage()->getDiskAdaptor();
   try {
     diskAdaptor->openExistingFile();
diff --git a/src/MultiDiskAdaptor.cc b/src/MultiDiskAdaptor.cc
index 7083de7f..729eb676 100644
--- a/src/MultiDiskAdaptor.cc
+++ b/src/MultiDiskAdaptor.cc
@@ -166,7 +166,7 @@ void MultiDiskAdaptor::resetDiskWriterEntries()
     return;
   }
 
-  for(std::deque<SharedHandle<FileEntry> >::const_iterator i =
+  for(std::vector<SharedHandle<FileEntry> >::const_iterator i =
 	fileEntries.begin(); i != fileEntries.end(); ++i) {
     diskWriterEntries.push_back
       (createDiskWriterEntry(*i, (*i)->isRequested()));
@@ -176,9 +176,9 @@ void MultiDiskAdaptor::resetDiskWriterEntries()
 
   // TODO Currently, pieceLength == 0 is used for unit testing only.
   if(pieceLength > 0) {
-    std::deque<SharedHandle<DiskWriterEntry> >::iterator done =
+    std::vector<SharedHandle<DiskWriterEntry> >::iterator done =
       diskWriterEntries.begin();
-    for(std::deque<SharedHandle<DiskWriterEntry> >::iterator itr =
+    for(std::vector<SharedHandle<DiskWriterEntry> >::iterator itr =
 	  diskWriterEntries.begin(); itr != diskWriterEntries.end();) {
       const SharedHandle<FileEntry>& fileEntry = (*itr)->getFileEntry();
 
@@ -189,7 +189,7 @@ void MultiDiskAdaptor::resetDiskWriterEntries()
       off_t pieceStartOffset =
 	(fileEntry->getOffset()/pieceLength)*pieceLength;
       if(itr != diskWriterEntries.begin()) {
-	for(std::deque<SharedHandle<DiskWriterEntry> >::iterator i =
+	for(std::vector<SharedHandle<DiskWriterEntry> >::iterator i =
 	      itr-1; true; --i) {
 	  const SharedHandle<FileEntry>& fileEntry = (*i)->getFileEntry();
 	  if(pieceStartOffset <= fileEntry->getOffset() ||
@@ -240,7 +240,7 @@ void MultiDiskAdaptor::resetDiskWriterEntries()
     }
   }
   DefaultDiskWriterFactory dwFactory;
-  for(std::deque<SharedHandle<DiskWriterEntry> >::iterator i =
+  for(std::vector<SharedHandle<DiskWriterEntry> >::iterator i =
 	diskWriterEntries.begin(); i != diskWriterEntries.end(); ++i) {
     if((*i)->needsFileAllocation() ||
        dwreq.find((*i)->getFileEntry()->getPath()) != dwreq.end() ||
@@ -260,7 +260,7 @@ void MultiDiskAdaptor::resetDiskWriterEntries()
 
 void MultiDiskAdaptor::mkdir() const
 {
-  for(std::deque<SharedHandle<DiskWriterEntry> >::const_iterator i =
+  for(std::vector<SharedHandle<DiskWriterEntry> >::const_iterator i =
 	diskWriterEntries.begin(); i != diskWriterEntries.end(); ++i) {
     (*i)->getFileEntry()->setupDir();
   }
@@ -279,7 +279,7 @@ void MultiDiskAdaptor::openIfNot
       // Cache is full. 
       // Choose one DiskWriterEntry randomly and close it.
       size_t index = SimpleRandomizer::getInstance()->getRandomNumber(numOpened);
-      std::deque<SharedHandle<DiskWriterEntry> >::iterator i =
+      std::vector<SharedHandle<DiskWriterEntry> >::iterator i =
 	_openedDiskWriterEntries.begin();
       std::advance(i, index);
       (*i)->closeFile();
@@ -443,7 +443,7 @@ ssize_t MultiDiskAdaptor::readData(unsigned char* data, size_t len, off_t offset
 
 bool MultiDiskAdaptor::fileExists()
 {
-  for(std::deque<SharedHandle<FileEntry> >::iterator i =
+  for(std::vector<SharedHandle<FileEntry> >::iterator i =
 	fileEntries.begin(); i != fileEntries.end(); ++i) {
     if((*i)->exists()) {
       return true;
@@ -455,10 +455,9 @@ bool MultiDiskAdaptor::fileExists()
 uint64_t MultiDiskAdaptor::size()
 {
   uint64_t size = 0;
-  for(DiskWriterEntries::const_iterator itr = diskWriterEntries.begin();
-      itr != diskWriterEntries.end(); ++itr) {
-    openIfNot(*itr, &DiskWriterEntry::openFile);
-    size += (*itr)->size();
+  for(std::vector<SharedHandle<FileEntry> >::iterator i =
+	fileEntries.begin(); i != fileEntries.end(); ++i) {
+    size += File((*i)->getPath()).size();
   }
   return size;
 }
@@ -496,7 +495,7 @@ void MultiDiskAdaptor::disableReadOnly()
 
 void MultiDiskAdaptor::cutTrailingGarbage()
 {
-  for(std::deque<SharedHandle<DiskWriterEntry> >::const_iterator i =
+  for(std::vector<SharedHandle<DiskWriterEntry> >::const_iterator i =
 	diskWriterEntries.begin(); i != diskWriterEntries.end(); ++i) {
     uint64_t length = (*i)->getFileEntry()->getLength();
     if(File((*i)->getFilePath()).size() > length) {
@@ -515,7 +514,7 @@ void MultiDiskAdaptor::setMaxOpenFiles(size_t maxOpenFiles)
 size_t MultiDiskAdaptor::utime(const Time& actime, const Time& modtime)
 {
   size_t numOK = 0;
-  for(std::deque<SharedHandle<FileEntry> >::const_iterator i =
+  for(std::vector<SharedHandle<FileEntry> >::const_iterator i =
 	fileEntries.begin(); i != fileEntries.end(); ++i) {
     if((*i)->isRequested()) {
       File f((*i)->getPath());
diff --git a/src/MultiDiskAdaptor.h b/src/MultiDiskAdaptor.h
index 21018259..74713fee 100644
--- a/src/MultiDiskAdaptor.h
+++ b/src/MultiDiskAdaptor.h
@@ -37,6 +37,8 @@
 
 #include "DiskAdaptor.h"
 
+#include <deque>
+
 namespace aria2 {
 
 class MultiFileAllocationIterator;
@@ -112,7 +114,7 @@ public:
 
 typedef SharedHandle<DiskWriterEntry> DiskWriterEntryHandle;
 
-typedef std::deque<DiskWriterEntryHandle> DiskWriterEntries;
+typedef std::vector<DiskWriterEntryHandle> DiskWriterEntries;
 
 class MultiDiskAdaptor : public DiskAdaptor {
   friend class MultiFileAllocationIterator;
@@ -120,7 +122,7 @@ private:
   size_t pieceLength;
   DiskWriterEntries diskWriterEntries;
 
-  std::deque<SharedHandle<DiskWriterEntry> > _openedDiskWriterEntries;
+  std::vector<SharedHandle<DiskWriterEntry> > _openedDiskWriterEntries;
 
   size_t _maxOpenFiles;
 
@@ -192,7 +194,7 @@ public:
 
   virtual size_t utime(const Time& actime, const Time& modtime);
 
-  const std::deque<SharedHandle<DiskWriterEntry> >&
+  const std::vector<SharedHandle<DiskWriterEntry> >&
   getDiskWriterEntries() const
   {
     return diskWriterEntries;
diff --git a/src/MultiFileAllocationIterator.cc b/src/MultiFileAllocationIterator.cc
index ff131573..a1f772af 100644
--- a/src/MultiFileAllocationIterator.cc
+++ b/src/MultiFileAllocationIterator.cc
@@ -45,7 +45,8 @@ namespace aria2 {
 
 MultiFileAllocationIterator::MultiFileAllocationIterator(MultiDiskAdaptor* diskAdaptor):
   _diskAdaptor(diskAdaptor),
-  _entries(_diskAdaptor->diskWriterEntries),
+  _entries(_diskAdaptor->diskWriterEntries.begin(),
+	   _diskAdaptor->diskWriterEntries.end()),
   _offset(0)
 {}
 
@@ -111,7 +112,8 @@ uint64_t MultiFileAllocationIterator::getTotalLength()
   }
 }
 
-const DiskWriterEntries& MultiFileAllocationIterator::getDiskWriterEntries() const
+const std::deque<SharedHandle<DiskWriterEntry> >&
+MultiFileAllocationIterator::getDiskWriterEntries() const
 {
   return _entries;
 }
diff --git a/src/MultiUrlRequestInfo.cc b/src/MultiUrlRequestInfo.cc
index c0fbb878..11351ad3 100644
--- a/src/MultiUrlRequestInfo.cc
+++ b/src/MultiUrlRequestInfo.cc
@@ -54,6 +54,7 @@
 #include "File.h"
 #include "Netrc.h"
 #include "AuthConfigFactory.h"
+#include "DownloadContext.h"
 #ifdef ENABLE_SSL
 # include "SocketCore.h"
 # include "TLSContext.h"
diff --git a/src/PeerChokeCommand.cc b/src/PeerChokeCommand.cc
index 8799605f..ca1bb1f0 100644
--- a/src/PeerChokeCommand.cc
+++ b/src/PeerChokeCommand.cc
@@ -34,18 +34,15 @@
 /* copyright --> */
 #include "PeerChokeCommand.h"
 #include "DownloadEngine.h"
-#include "BtContext.h"
 #include "BtRuntime.h"
 #include "PeerStorage.h"
 
 namespace aria2 {
 
 PeerChokeCommand::PeerChokeCommand(int32_t cuid,
-				   DownloadEngine* e,
-				   const SharedHandle<BtContext>& btContext):
+				   DownloadEngine* e):
   Command(cuid),
-  e(e),
-  _btContext(btContext) {}
+  e(e) {}
 
 PeerChokeCommand::~PeerChokeCommand() {}
 
diff --git a/src/PeerChokeCommand.h b/src/PeerChokeCommand.h
index b81781f3..7f8baf75 100644
--- a/src/PeerChokeCommand.h
+++ b/src/PeerChokeCommand.h
@@ -41,7 +41,6 @@
 namespace aria2 {
 
 class DownloadEngine;
-class BtContext;
 class BtRuntime;
 class PeerStorage;
 
@@ -49,15 +48,12 @@ class PeerChokeCommand : public Command {
 private:
   DownloadEngine* e;
 
-  SharedHandle<BtContext> _btContext;
-
   SharedHandle<PeerStorage> _peerStorage;
 
   SharedHandle<BtRuntime> _btRuntime;
 public:
   PeerChokeCommand(int32_t cuid,
-		   DownloadEngine* e,
-		   const SharedHandle<BtContext>& btContext);
+		   DownloadEngine* e);
 
   virtual ~PeerChokeCommand();
 
diff --git a/src/PeerInitiateConnectionCommand.cc b/src/PeerInitiateConnectionCommand.cc
index a815bced..bd16a354 100644
--- a/src/PeerInitiateConnectionCommand.cc
+++ b/src/PeerInitiateConnectionCommand.cc
@@ -42,12 +42,12 @@
 #include "Socket.h"
 #include "Logger.h"
 #include "Peer.h"
-#include "BtContext.h"
 #include "BtRuntime.h"
 #include "PeerStorage.h"
 #include "PieceStorage.h"
 #include "PeerConnection.h"
 #include "RequestGroup.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
@@ -56,13 +56,11 @@ PeerInitiateConnectionCommand::PeerInitiateConnectionCommand
  RequestGroup* requestGroup,
  const PeerHandle& peer,
  DownloadEngine* e,
- const SharedHandle<BtContext>& btContext,
  const SharedHandle<BtRuntime>& btRuntime,
  bool mseHandshakeEnabled)
   :
   PeerAbstractCommand(cuid, peer, e),
   _requestGroup(requestGroup),
-  _btContext(btContext),
   _btRuntime(btRuntime),
   _mseHandshakeEnabled(mseHandshakeEnabled)
 {
@@ -83,7 +81,7 @@ bool PeerInitiateConnectionCommand::executeInternal() {
   socket->establishConnection(peer->ipaddr, peer->port);
   if(_mseHandshakeEnabled) {
     InitiatorMSEHandshakeCommand* c =
-      new InitiatorMSEHandshakeCommand(cuid, _requestGroup, peer, e, _btContext,
+      new InitiatorMSEHandshakeCommand(cuid, _requestGroup, peer, e,
 				       _btRuntime, socket);
     c->setPeerStorage(_peerStorage);
     c->setPieceStorage(_pieceStorage);
@@ -91,7 +89,7 @@ bool PeerInitiateConnectionCommand::executeInternal() {
   } else {
     PeerInteractionCommand* command =
       new PeerInteractionCommand
-      (cuid, _requestGroup, peer, e, _btContext, _btRuntime, _pieceStorage,
+      (cuid, _requestGroup, peer, e, _btRuntime, _pieceStorage,
        socket, PeerInteractionCommand::INITIATOR_SEND_HANDSHAKE);
     command->setPeerStorage(_peerStorage);
     e->commands.push_back(command);
@@ -106,7 +104,7 @@ bool PeerInitiateConnectionCommand::prepareForNextPeer(time_t wait) {
     peer->usedBy(e->newCUID());
     PeerInitiateConnectionCommand* command =
       new PeerInitiateConnectionCommand(peer->usedBy(), _requestGroup, peer, e,
-					_btContext, _btRuntime);
+					_btRuntime);
     command->setPeerStorage(_peerStorage);
     command->setPieceStorage(_pieceStorage);
     e->commands.push_back(command);
diff --git a/src/PeerInitiateConnectionCommand.h b/src/PeerInitiateConnectionCommand.h
index 9ffd5afa..0723eade 100644
--- a/src/PeerInitiateConnectionCommand.h
+++ b/src/PeerInitiateConnectionCommand.h
@@ -40,7 +40,6 @@
 namespace aria2 {
 
 class RequestGroup;
-class BtContext;
 class BtRuntime;
 class PeerStorage;
 class PieceStorage;
@@ -49,8 +48,6 @@ class PeerInitiateConnectionCommand : public PeerAbstractCommand {
 private:
   RequestGroup* _requestGroup;
 
-  SharedHandle<BtContext> _btContext;
-
   SharedHandle<BtRuntime> _btRuntime;
 
   SharedHandle<PeerStorage> _peerStorage;
@@ -69,7 +66,6 @@ public:
 				RequestGroup* requestGroup,
 				const SharedHandle<Peer>& peer,
 				DownloadEngine* e,
-				const SharedHandle<BtContext>& btContext,
 				const SharedHandle<BtRuntime>& btRuntime,
 				bool mseHandshakeEnabled = true);
 
diff --git a/src/PeerInteractionCommand.cc b/src/PeerInteractionCommand.cc
index c3bbc1b9..38644aaf 100644
--- a/src/PeerInteractionCommand.cc
+++ b/src/PeerInteractionCommand.cc
@@ -44,7 +44,7 @@
 #include "prefs.h"
 #include "Socket.h"
 #include "Option.h"
-#include "BtContext.h"
+#include "DownloadContext.h"
 #include "BtRegistry.h"
 #include "Peer.h"
 #include "BtMessage.h"
@@ -70,6 +70,7 @@
 #include "DefaultExtensionMessageFactory.h"
 #include "RequestGroupMan.h"
 #include "ExtensionMessageRegistry.h"
+#include "bittorrent_helper.h"
 
 namespace aria2 {
 
@@ -78,7 +79,6 @@ PeerInteractionCommand::PeerInteractionCommand
  RequestGroup* requestGroup,
  const PeerHandle& p,
  DownloadEngine* e,
- const SharedHandle<BtContext>& btContext,
  const SharedHandle<BtRuntime>& btRuntime,
  const SharedHandle<PieceStorage>& pieceStorage,
  const SocketHandle& s,
@@ -86,7 +86,6 @@ PeerInteractionCommand::PeerInteractionCommand
  const PeerConnectionHandle& passedPeerConnection)
   :PeerAbstractCommand(cuid, p, e, s),
    _requestGroup(requestGroup),
-   _btContext(btContext),
    _btRuntime(btRuntime),
    _pieceStorage(pieceStorage),
    sequence(sequence)
@@ -98,20 +97,22 @@ PeerInteractionCommand::PeerInteractionCommand
     setTimeout(getOption()->getAsInt(PREF_PEER_CONNECTION_TIMEOUT));
   }
 
+  const BDE& torrentAttrs =
+    _requestGroup->getDownloadContext()->getAttribute(bittorrent::BITTORRENT);
   SharedHandle<BtRegistry> btRegistry = e->getBtRegistry();
   SharedHandle<PeerStorage> peerStorage =
-    btRegistry->get(_btContext->getInfoHashAsString())._peerStorage;
+    btRegistry->get(torrentAttrs[bittorrent::INFO_HASH].s())._peerStorage;
 
   SharedHandle<ExtensionMessageRegistry> exMsgRegistry
     (new ExtensionMessageRegistry());
 
   SharedHandle<DefaultExtensionMessageFactory> extensionMessageFactory
-    (new DefaultExtensionMessageFactory(_btContext, peer, exMsgRegistry));
+    (new DefaultExtensionMessageFactory(peer, exMsgRegistry));
   extensionMessageFactory->setPeerStorage(peerStorage);
 
   SharedHandle<DefaultBtMessageFactory> factory(new DefaultBtMessageFactory());
   factory->setCuid(cuid);
-  factory->setBtContext(_btContext);
+  factory->setDownloadContext(_requestGroup->getDownloadContext());
   factory->setPieceStorage(pieceStorage);
   factory->setPeerStorage(peerStorage);
   factory->setExtensionMessageFactory(extensionMessageFactory);
@@ -132,7 +133,7 @@ PeerInteractionCommand::PeerInteractionCommand
     (new DefaultBtMessageDispatcher());
   dispatcher->setCuid(cuid);
   dispatcher->setPeer(peer);
-  dispatcher->setBtContext(_btContext);
+  dispatcher->setDownloadContext(_requestGroup->getDownloadContext());
   dispatcher->setPieceStorage(pieceStorage);
   dispatcher->setPeerStorage(peerStorage);
   dispatcher->setRequestTimeout(getOption()->getAsInt(PREF_BT_REQUEST_TIMEOUT));
@@ -142,7 +143,7 @@ PeerInteractionCommand::PeerInteractionCommand
   DefaultBtMessageReceiverHandle receiver(new DefaultBtMessageReceiver());
   receiver->setCuid(cuid);
   receiver->setPeer(peer);
-  receiver->setBtContext(_btContext);
+  receiver->setDownloadContext(_requestGroup->getDownloadContext());
   receiver->setPeerConnection(peerConnection);
   receiver->setDispatcher(dispatcher);
   receiver->setBtMessageFactory(factory);
@@ -151,13 +152,12 @@ PeerInteractionCommand::PeerInteractionCommand
     (new DefaultBtRequestFactory());
   reqFactory->setCuid(cuid);
   reqFactory->setPeer(peer);
-  reqFactory->setBtContext(_btContext);
   reqFactory->setPieceStorage(pieceStorage);
   reqFactory->setBtMessageDispatcher(dispatcher);
   reqFactory->setBtMessageFactory(factory);
 
   DefaultBtInteractiveHandle btInteractive
-    (new DefaultBtInteractive(_btContext, peer));
+    (new DefaultBtInteractive(_requestGroup->getDownloadContext(), peer));
   btInteractive->setBtRuntime(_btRuntime);
   btInteractive->setPieceStorage(_pieceStorage);
   btInteractive->setPeerStorage(peerStorage); // Note: Not a member variable.
@@ -172,7 +172,7 @@ PeerInteractionCommand::PeerInteractionCommand
     (getOption()->getAsInt(PREF_BT_KEEP_ALIVE_INTERVAL));
   btInteractive->setRequestGroupMan(e->_requestGroupMan);
   btInteractive->setBtMessageFactory(factory);
-  if(!_btContext->isPrivate()) {
+  if(torrentAttrs[bittorrent::PRIVATE].i() == 0) {
     if(getOption()->getAsBool(PREF_ENABLE_PEER_EXCHANGE)) {
       btInteractive->setUTPexEnabled(true);
     }
@@ -189,8 +189,9 @@ PeerInteractionCommand::PeerInteractionCommand
   factory->setBtRequestFactory(reqFactory);
   factory->setPeerConnection(peerConnection);
 
-  peer->allocateSessionResource(_btContext->getPieceLength(),
-				_btContext->getTotalLength());
+  peer->allocateSessionResource
+    (_requestGroup->getDownloadContext()->getPieceLength(),
+     _requestGroup->getDownloadContext()->getTotalLength());
   peer->setBtMessageDispatcher(dispatcher);
 
   _btRuntime->increaseConnections();
@@ -290,12 +291,8 @@ bool PeerInteractionCommand::prepareForNextPeer(time_t wait) {
     PeerHandle peer = _peerStorage->getUnusedPeer();
     peer->usedBy(e->newCUID());
     PeerInitiateConnectionCommand* command =
-      new PeerInitiateConnectionCommand(peer->usedBy(),
-					_requestGroup,
-					peer,
-					e,
-					_btContext,
-					_btRuntime);
+      new PeerInitiateConnectionCommand
+      (peer->usedBy(), _requestGroup, peer, e, _btRuntime);
     command->setPeerStorage(_peerStorage);
     command->setPieceStorage(_pieceStorage);
     e->commands.push_back(command);
diff --git a/src/PeerInteractionCommand.h b/src/PeerInteractionCommand.h
index a8ed8514..894cda7d 100644
--- a/src/PeerInteractionCommand.h
+++ b/src/PeerInteractionCommand.h
@@ -40,7 +40,6 @@
 namespace aria2 {
 
 class RequestGroup;
-class BtContext;
 class BtInteractive;
 class PeerConnection;
 class BtRuntime;
@@ -58,8 +57,6 @@ public:
 private:
   RequestGroup* _requestGroup;
 
-  SharedHandle<BtContext> _btContext;
-
   SharedHandle<BtRuntime> _btRuntime;
 
   SharedHandle<PieceStorage> _pieceStorage;
@@ -81,7 +78,6 @@ public:
 			 RequestGroup* requestGroup,
 			 const SharedHandle<Peer>& peer,
 			 DownloadEngine* e,
-			 const SharedHandle<BtContext>& btContext,
 			 const SharedHandle<BtRuntime>& btRuntime,
 			 const SharedHandle<PieceStorage>& pieceStorage,
 			 const SharedHandle<SocketCore>& s,
diff --git a/src/PeerReceiveHandshakeCommand.cc b/src/PeerReceiveHandshakeCommand.cc
index 20df4391..043ec7c2 100644
--- a/src/PeerReceiveHandshakeCommand.cc
+++ b/src/PeerReceiveHandshakeCommand.cc
@@ -37,7 +37,7 @@
 #include "DownloadEngine.h"
 #include "BtHandshakeMessage.h"
 #include "Util.h"
-#include "BtContext.h"
+#include "DownloadContext.h"
 #include "DlAbortEx.h"
 #include "PeerInteractionCommand.h"
 #include "Peer.h"
@@ -91,23 +91,25 @@ bool PeerReceiveHandshakeCommand::executeInternal()
   // To handle tracker's NAT-checking feature
   if(dataLength >= 48) {
     // check info_hash
-    std::string infoHash = Util::toHex(&data[28], INFO_HASH_LENGTH);
+    std::string infoHash = std::string(&data[28], &data[28+INFO_HASH_LENGTH]);
 
     BtObject btObject = e->getBtRegistry()->get(infoHash);
-    SharedHandle<BtContext> btContext = btObject._btContext;
+    SharedHandle<DownloadContext> downloadContext = btObject._downloadContext;
     SharedHandle<BtRuntime> btRuntime = btObject._btRuntime;
     SharedHandle<PieceStorage> pieceStorage = btObject._pieceStorage;
     SharedHandle<PeerStorage> peerStorage = btObject._peerStorage;
 
-    if(btContext.isNull() || !btRuntime->ready()) {
+    if(downloadContext.isNull() || !btRuntime->ready()) {
       throw DL_ABORT_EX
-	(StringFormat("Unknown info hash %s", infoHash.c_str()).str());
+	(StringFormat("Unknown info hash %s",
+		      Util::toHex(infoHash).c_str()).str());
     }
-    TransferStat tstat = btContext->getOwnerRequestGroup()->calculateStat();
+    TransferStat tstat =
+      downloadContext->getOwnerRequestGroup()->calculateStat();
     const unsigned int maxDownloadLimit =
-      btContext->getOwnerRequestGroup()->getMaxDownloadSpeedLimit();
+      downloadContext->getOwnerRequestGroup()->getMaxDownloadSpeedLimit();
     unsigned int thresholdSpeed =
-      btContext->getOwnerRequestGroup()->
+      downloadContext->getOwnerRequestGroup()->
       getOption()->getAsInt(PREF_BT_REQUEST_PEER_SPEED_LIMIT);
     if(maxDownloadLimit > 0) {
       thresholdSpeed = std::min(maxDownloadLimit, thresholdSpeed);
@@ -123,10 +125,9 @@ bool PeerReceiveHandshakeCommand::executeInternal()
 	PeerInteractionCommand* command =
 	  new PeerInteractionCommand
 	  (cuid,
-	   btContext->getOwnerRequestGroup(),
+	   downloadContext->getOwnerRequestGroup(),
 	   peer,
 	   e,
-	   btContext,
 	   btRuntime,
 	   pieceStorage,
 	   socket,
diff --git a/src/PieceHashCheckIntegrityEntry.cc b/src/PieceHashCheckIntegrityEntry.cc
index 188e8670..972a40e8 100644
--- a/src/PieceHashCheckIntegrityEntry.cc
+++ b/src/PieceHashCheckIntegrityEntry.cc
@@ -48,8 +48,10 @@ PieceHashCheckIntegrityEntry::~PieceHashCheckIntegrityEntry() {}
 
 bool PieceHashCheckIntegrityEntry::isValidationReady()
 {
-  DownloadContextHandle dctx = _requestGroup->getDownloadContext();
-  return dctx->getPieceHashes().size() > 0 &&
+  const SharedHandle<DownloadContext>& dctx =
+    _requestGroup->getDownloadContext();
+  return !dctx->getPieceHashAlgo().empty() &&
+    dctx->getPieceHashes().size() > 0 &&
     dctx->getPieceHashes().size() == dctx->getNumPieces();
 }
 
diff --git a/src/RealtimeCommand.cc b/src/RealtimeCommand.cc
index 0f444ee4..160f1f00 100644
--- a/src/RealtimeCommand.cc
+++ b/src/RealtimeCommand.cc
@@ -36,6 +36,7 @@
 #include "DownloadEngine.h"
 #include "Exception.h"
 #include "RequestGroup.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/ReceiverMSEHandshakeCommand.cc b/src/ReceiverMSEHandshakeCommand.cc
index defe2a22..fa609b60 100644
--- a/src/ReceiverMSEHandshakeCommand.cc
+++ b/src/ReceiverMSEHandshakeCommand.cc
@@ -49,7 +49,7 @@
 #include "ARC4Decryptor.h"
 #include "RequestGroupMan.h"
 #include "BtRegistry.h"
-#include "BtContext.h"
+#include "DownloadContext.h"
 #include "PeerStorage.h"
 #include "PieceStorage.h"
 #include "BtAnnounce.h"
@@ -135,9 +135,10 @@ bool ReceiverMSEHandshakeCommand::executeInternal()
     break;
   }
   case RECEIVER_RECEIVE_PAD_C_LENGTH: {
-    std::deque<SharedHandle<BtContext> > btContexts;
-    e->getBtRegistry()->getAllBtContext(std::back_inserter(btContexts));
-    if(_mseHandshake->receiveReceiverHashAndPadCLength(btContexts)) {
+    std::deque<SharedHandle<DownloadContext> > downloadContexts;
+    e->getBtRegistry()->getAllDownloadContext
+      (std::back_inserter(downloadContexts));
+    if(_mseHandshake->receiveReceiverHashAndPadCLength(downloadContexts)) {
       _sequence = RECEIVER_RECEIVE_PAD_C;
     }
     break;
diff --git a/src/RequestGroup.cc b/src/RequestGroup.cc
index 0da471b9..2e7d9096 100644
--- a/src/RequestGroup.cc
+++ b/src/RequestGroup.cc
@@ -48,7 +48,6 @@
 #include "File.h"
 #include "message.h"
 #include "Util.h"
-#include "BtRegistry.h"
 #include "LogFactory.h"
 #include "Logger.h"
 #include "DiskAdaptor.h"
@@ -57,8 +56,7 @@
 #include "StreamCheckIntegrityEntry.h"
 #include "CheckIntegrityCommand.h"
 #include "UnknownLengthPieceStorage.h"
-#include "BtContext.h"
-#include "SingleFileDownloadContext.h"
+#include "DownloadContext.h"
 #include "DlAbortEx.h"
 #include "DownloadFailureException.h"
 #include "RequestGroupMan.h"
@@ -83,6 +81,8 @@
 # include "CheckIntegrityCommand.h"
 #endif // ENABLE_MESSAGE_DIGEST
 #ifdef ENABLE_BITTORRENT
+# include "bittorrent_helper.h"
+# include "BtRegistry.h"
 # include "BtCheckIntegrityEntry.h"
 # include "DefaultPeerStorage.h"
 # include "DefaultBtAnnounce.h"
@@ -205,39 +205,30 @@ void RequestGroup::createInitialCommand(std::deque<Command*>& commands,
 {
 #ifdef ENABLE_BITTORRENT
   {
-    BtContextHandle btContext = dynamic_pointer_cast<BtContext>(_downloadContext);
-    if(!btContext.isNull()) {
+    if(_downloadContext->hasAttribute(bittorrent::BITTORRENT)) {
+      const BDE& torrentAttrs =
+	_downloadContext->getAttribute(bittorrent::BITTORRENT);
       if(_option->getAsBool(PREF_DRY_RUN)) {
 	throw DOWNLOAD_FAILURE_EXCEPTION
 	  ("Cancel BitTorrent download in dry-run context.");
       }
       SharedHandle<BtRegistry> btRegistry = e->getBtRegistry();
-      if(!btRegistry->getBtContext(btContext->getInfoHashAsString()).isNull()) {
+      if(!btRegistry->getDownloadContext
+	 (torrentAttrs[bittorrent::INFO_HASH].s()).isNull()) {
 	throw DOWNLOAD_FAILURE_EXCEPTION
-	  (StringFormat("InfoHash %s is already registered.",
-			btContext->getInfoHashAsString().c_str()).str());
+	  (StringFormat
+	   ("InfoHash %s is already registered.",
+	    Util::toHex(torrentAttrs[bittorrent::INFO_HASH].s()).c_str()).str());
       }
 
       if(e->_requestGroupMan->isSameFileBeingDownloaded(this)) {
 	throw DOWNLOAD_FAILURE_EXCEPTION
 	  (StringFormat(EX_DUPLICATE_FILE_DOWNLOAD,
-			getFilePath().c_str()).str());
+			_downloadContext->getBasePath().c_str()).str());
       }
       initPieceStorage();
-      if(btContext->getFileEntries().size() > 1) {
-	// this is really multi file torrent.
-	// clear http/ftp uris because the current implementation does not
-	// allow integrating multi-file torrent and http/ftp.
-	_logger->debug("Clearing http/ftp URIs because the current implementation does not allow integrating multi-file torrent and http/ftp.");
-	_uris.clear();
-
+      if(_downloadContext->getFileEntries().size() > 1) {
 	_pieceStorage->setupFileFilter();
-      } else if(btContext->getFileEntries().size() == 1) {
-	// web-seeding is only enabled for single file torrent
-	SharedHandle<FileEntry> fileEntry = btContext->getFileEntries().front();
-	_uris.insert(_uris.end(),
-		     fileEntry->getAssociatedUris().begin(),
-		     fileEntry->getAssociatedUris().end());
       }
       
       SharedHandle<DefaultBtProgressInfoFile>
@@ -252,14 +243,14 @@ void RequestGroup::createInitialCommand(std::deque<Command*>& commands,
       progressInfoFile->setBtRuntime(btRuntime);
 
       SharedHandle<DefaultPeerStorage> peerStorage
-	(new DefaultPeerStorage(btContext, _option.get()));
+	(new DefaultPeerStorage(_option.get()));
       peerStorage->setBtRuntime(btRuntime);
       peerStorage->setPieceStorage(_pieceStorage);
       _peerStorage = peerStorage;
       progressInfoFile->setPeerStorage(peerStorage);
 
       SharedHandle<DefaultBtAnnounce> btAnnounce
-	(new DefaultBtAnnounce(btContext, _option.get()));
+	(new DefaultBtAnnounce(_downloadContext, _option.get()));
       btAnnounce->setBtRuntime(btRuntime);
       btAnnounce->setPieceStorage(_pieceStorage);
       btAnnounce->setPeerStorage(peerStorage);
@@ -267,8 +258,8 @@ void RequestGroup::createInitialCommand(std::deque<Command*>& commands,
 	(_option->getAsInt(PREF_BT_TRACKER_INTERVAL));
       btAnnounce->shuffleAnnounce();
       
-      btRegistry->put(btContext->getInfoHashAsString(),
-		      BtObject(btContext,
+      btRegistry->put(torrentAttrs[bittorrent::INFO_HASH].s(),
+		      BtObject(_downloadContext,
 			       _pieceStorage,
 			       peerStorage,
 			       btAnnounce,
@@ -280,20 +271,20 @@ void RequestGroup::createInitialCommand(std::deque<Command*>& commands,
 	progressInfoFile->removeFile();
 	_logger->notice(MSG_REMOVED_DEFUNCT_CONTROL_FILE,
 			progressInfoFile->getFilename().c_str(),
-			getFilePath().c_str());
+			_downloadContext->getBasePath().c_str());
       }
       {
 	uint64_t actualFileSize = _pieceStorage->getDiskAdaptor()->size();
-	if(actualFileSize == btContext->getTotalLength()) {
+	if(actualFileSize == _downloadContext->getTotalLength()) {
 	  // First, make DiskAdaptor read-only mode to allow the
 	  // program to seed file in read-only media.
 	  _pieceStorage->getDiskAdaptor()->enableReadOnly();
 	} else {
 	  // Open file in writable mode to allow the program
-	  // truncate the file to btContext->getTotalLength()
+	  // truncate the file to _downloadContext->getTotalLength()
 	  _logger->debug("File size not match. File is opened in writable mode."
 			 " Expected:%s Actual:%s",
-			 Util::uitos(btContext->getTotalLength()).c_str(),
+			 Util::uitos(_downloadContext->getTotalLength()).c_str(),
 			 Util::uitos(actualFileSize).c_str());
 	}
       }
@@ -311,7 +302,7 @@ void RequestGroup::createInitialCommand(std::deque<Command*>& commands,
 	    throw DOWNLOAD_FAILURE_EXCEPTION
 	      (StringFormat
 	       (MSG_FILE_ALREADY_EXISTS,
-		getFilePath().c_str()).str());
+		_downloadContext->getBasePath().c_str()).str());
 	  } else {
 	    _pieceStorage->getDiskAdaptor()->openFile();
 	  }
@@ -324,14 +315,22 @@ void RequestGroup::createInitialCommand(std::deque<Command*>& commands,
       }
       _progressInfoFile = progressInfoFile;
 
-      if(!btContext->isPrivate() && _option->getAsBool(PREF_ENABLE_DHT)) {
+      if(torrentAttrs[bittorrent::PRIVATE].i() == 0 &&
+	 _option->getAsBool(PREF_ENABLE_DHT)) {
 	std::deque<Command*> commands;
 	DHTSetup().setup(commands, e, _option.get());
 	e->addCommand(commands);
-	if(!btContext->getNodes().empty() && DHTSetup::initialized()) {
+	if(!torrentAttrs[bittorrent::NODES].empty() && DHTSetup::initialized()) {
+	  std::deque<std::pair<std::string, uint16_t> > entryPoints;
+	  const BDE& nodes = torrentAttrs[bittorrent::NODES];
+	  for(BDE::List::const_iterator i = nodes.listBegin();
+	      i != nodes.listEnd(); ++i) {
+	    std::pair<std::string, uint16_t> addr
+	      ((*i)[bittorrent::HOSTNAME].s(), (*i)[bittorrent::PORT].i());
+	    entryPoints.push_back(addr);
+	  }
 	  DHTEntryPointNameResolveCommand* command =
-	    new DHTEntryPointNameResolveCommand(e->newCUID(), e,
-						btContext->getNodes());
+	    new DHTEntryPointNameResolveCommand(e->newCUID(), e, entryPoints);
 	  command->setTaskQueue(DHTRegistry::_taskQueue);
 	  command->setTaskFactory(DHTRegistry::_taskFactory);
 	  command->setRoutingTable(DHTRegistry::_routingTable);
@@ -361,8 +360,10 @@ void RequestGroup::createInitialCommand(std::deque<Command*>& commands,
     if(e->_requestGroupMan->isSameFileBeingDownloaded(this)) {
       throw DOWNLOAD_FAILURE_EXCEPTION
 	(StringFormat(EX_DUPLICATE_FILE_DOWNLOAD,
-		      getFilePath().c_str()).str());
+		      _downloadContext->getBasePath().c_str()).str());
     }
+    // TODO1.5 Renaming filename doesn't take into account of
+    // multi-file download.
     adjustFilename
       (SharedHandle<BtProgressInfoFile>(new DefaultBtProgressInfoFile
 					(_downloadContext,
@@ -375,7 +376,7 @@ void RequestGroup::createInitialCommand(std::deque<Command*>& commands,
     if(!infoFile->exists() && downloadFinishedByFileLength()) {
       _pieceStorage->markAllPiecesDone();
       _logger->notice(MSG_DOWNLOAD_ALREADY_COMPLETED,
-		      _gid, getFilePath().c_str());
+		      _gid, _downloadContext->getBasePath().c_str());
     } else {
       loadAndOpenFile(infoFile);
       SharedHandle<CheckIntegrityEntry> checkIntegrityEntry
@@ -412,7 +413,7 @@ void RequestGroup::initPieceStorage()
     // downloads. Currently multi-file integrated download is not supported.
     if(!_uris.empty() &&
        _downloadContext->getFileEntries().size() == 1 &&
-       !dynamic_pointer_cast<BtContext>(_downloadContext).isNull()) {
+       _downloadContext->hasAttribute(bittorrent::BITTORRENT)) {
       _logger->debug("Using LongestSequencePieceSelector");
       ps->setPieceSelector
 	(SharedHandle<PieceSelector>(new LongestSequencePieceSelector()));
@@ -449,8 +450,7 @@ bool RequestGroup::downloadFinishedByFileLength()
   if(!_downloadContext->knowsTotalLength()) {
     return false;
   }
-  // TODO consider the case when the getFilePath() returns dir path. 
-  File outfile(getFilePath());
+  File outfile(getFirstFilePath());
   if(outfile.exists() && _downloadContext->getTotalLength() == outfile.size()) {
     return true;
   } else {
@@ -468,7 +468,7 @@ void RequestGroup::adjustFilename
   } else if(downloadFinishedByFileLength()) {
     // File was downloaded already, no need to change file name.
   } else {
-    File outfile(getFilePath());    
+    File outfile(getFirstFilePath());    
     if(outfile.exists() && _option->getAsBool(PREF_CONTINUE) &&
        outfile.size() <= _downloadContext->getTotalLength()) {
       // File exists but user decided to resume it.
@@ -498,14 +498,14 @@ void RequestGroup::loadAndOpenFile(const BtProgressInfoFileHandle& progressInfoF
       progressInfoFile->removeFile();
       _logger->notice(MSG_REMOVED_DEFUNCT_CONTROL_FILE,
 		      progressInfoFile->getFilename().c_str(),
-		      getFilePath().c_str());
+		      _downloadContext->getBasePath().c_str());
     }
 
     if(progressInfoFile->exists()) {
       progressInfoFile->load();
       _pieceStorage->getDiskAdaptor()->openExistingFile();
     } else {
-      File outfile(getFilePath());    
+      File outfile(getFirstFilePath());    
       if(outfile.exists() && _option->getAsBool(PREF_CONTINUE) &&
 	 outfile.size() <= getTotalLength()) {
 	_pieceStorage->getDiskAdaptor()->openExistingFile();
@@ -535,43 +535,36 @@ void RequestGroup::shouldCancelDownloadForSafety()
   if(_option->getAsBool(PREF_ALLOW_OVERWRITE)) {
     return;
   }
-  File outfile(getFilePath());
+  File outfile(getFirstFilePath());
   if(outfile.exists()) {
     if(_option->getAsBool(PREF_AUTO_FILE_RENAMING)) {
       if(tryAutoFileRenaming()) {
-	_logger->notice(MSG_FILE_RENAMED, getFilePath().c_str());
+	_logger->notice(MSG_FILE_RENAMED, getFirstFilePath().c_str());
       } else {
 	throw DOWNLOAD_FAILURE_EXCEPTION
 	  (StringFormat("File renaming failed: %s",
-			getFilePath().c_str()).str());
+			getFirstFilePath().c_str()).str());
       }
     } else {
       throw DOWNLOAD_FAILURE_EXCEPTION
 	(StringFormat(MSG_FILE_ALREADY_EXISTS,
-		      getFilePath().c_str()).str());
+		      getFirstFilePath().c_str()).str());
     }
   }
 }
 
 bool RequestGroup::tryAutoFileRenaming()
 {
-  std::string filepath = getFilePath();
+  std::string filepath = getFirstFilePath();
   if(filepath.empty()) {
     return false;
   }
-  SingleFileDownloadContextHandle ctx =
-    dynamic_pointer_cast<SingleFileDownloadContext>(_downloadContext);
-  // Make a copy of ctx.
-  SingleFileDownloadContextHandle tempCtx(new SingleFileDownloadContext(*ctx.get()));
-
-  DefaultBtProgressInfoFile tempInfoFile(tempCtx, SharedHandle<PieceStorage>(), 0);
-
   for(unsigned int i = 1; i < 10000; ++i) {
     File newfile(strconcat(filepath, ".", Util::uitos(i)));
-    tempCtx->setUFilename(newfile.getPath());
-    tempInfoFile.updateFilename();
-    if(!newfile.exists() || (newfile.exists() && tempInfoFile.exists())) {
-      ctx->setUFilename(newfile.getPath());
+    // TODO1.5 hard coded ".aria2" extension.
+    File ctrlfile(newfile.getPath()+".aria2");
+    if(!newfile.exists() || (newfile.exists() && ctrlfile.exists())) {
+      _downloadContext->getFirstFileEntry()->setPath(newfile.getPath());
       return true;
     }
   }
@@ -639,8 +632,8 @@ void RequestGroup::createNextCommand(std::deque<Command*>& commands,
 		     static_cast<unsigned int>(_uris.size()));
     }
   }
-
   std::deque<std::string> pendingURIs;
+
   for(; numCommand--; ) {
     Command* command = new CreateRequestCommand(e->newCUID(), this, e);
     _logger->debug("filePath=%s", _downloadContext->getFileEntries().front()->getPath().c_str());
@@ -685,14 +678,14 @@ void RequestGroup::createNextCommand(std::deque<Command*>& commands,
   }
 }
 
-std::string RequestGroup::getFilePath() const
+std::string RequestGroup::getFirstFilePath() const
 {
   assert(!_downloadContext.isNull());
   if(inMemoryDownload()) {
     static const std::string DIR_MEMORY("[MEMORY]");
-    return DIR_MEMORY+File(_downloadContext->getActualBasePath()).getBasename();
+    return DIR_MEMORY+File(_downloadContext->getFirstFileEntry()->getPath()).getBasename();
   } else {
-    return _downloadContext->getActualBasePath();
+    return _downloadContext->getFirstFileEntry()->getPath();
   }
 }
 
@@ -827,24 +820,25 @@ void RequestGroup::setForceHaltRequested(bool f, HaltReason haltReason)
 void RequestGroup::releaseRuntimeResource(DownloadEngine* e)
 {
 #ifdef ENABLE_BITTORRENT
-  BtContextHandle btContext = dynamic_pointer_cast<BtContext>(_downloadContext);
-  if(!btContext.isNull()) {
+  if(_downloadContext->hasAttribute(bittorrent::BITTORRENT)) {
     SharedHandle<BtRegistry> btRegistry = e->getBtRegistry();
-    BtContextHandle btContextInReg =
-      btRegistry->getBtContext(btContext->getInfoHashAsString());
-    // Make sure that the registered BtContext's GID is equal to
-    // this->getGID().  Even if createInitialCommand() throws
-    // exception without registering this BtContext, after that, this
-    // method is called. In this case, just finding BtContext using
-    // infoHash may detect another download's BtContext and deleting
-    // it from BtRegistry causes Segmentation Fault.
-    if(!btContextInReg.isNull() &&
-       btContextInReg->getOwnerRequestGroup()->getGID() ==
-	btContext->getOwnerRequestGroup()->getGID()) {
-      btRegistry->remove(btContext->getInfoHashAsString());
+    const BDE& torrentAttrs =
+      _downloadContext->getAttribute(bittorrent::BITTORRENT);
+    const std::string& infoHash = torrentAttrs[bittorrent::INFO_HASH].s();
+    SharedHandle<DownloadContext> contextInReg =
+      btRegistry->getDownloadContext(infoHash);
+    // Make sure that the registered DownloadContext's GID is equal to
+    // _gid.  Even if createInitialCommand() throws exception without
+    // registering this DownloadContext, after that, this method is
+    // called. In this case, just finding DownloadContext using
+    // infoHash may detect another download's DownloadContext and
+    // deleting it from BtRegistry causes Segmentation Fault.
+    if(!contextInReg.isNull() &&
+       contextInReg->getOwnerRequestGroup()->getGID() == _gid) {
+      btRegistry->remove(infoHash);
       if(!DHTRegistry::_peerAnnounceStorage.isNull()) {
-	DHTRegistry::_peerAnnounceStorage->
-	  removeLocalPeerAnnounce(btContext->getInfoHash());
+	DHTRegistry::_peerAnnounceStorage->removeLocalPeerAnnounce
+	  (torrentAttrs[bittorrent::INFO_HASH].uc());
       }
     }
   }
@@ -856,7 +850,8 @@ void RequestGroup::releaseRuntimeResource(DownloadEngine* e)
 
 void RequestGroup::preDownloadProcessing()
 {
-  _logger->debug("Finding PreDownloadHandler for path %s.", getFilePath().c_str());
+  _logger->debug("Finding PreDownloadHandler for path %s.",
+		 getFirstFilePath().c_str());
   try {
     for(PreDownloadHandlers::const_iterator itr = _preDownloadHandlers.begin();
 	itr != _preDownloadHandlers.end(); ++itr) {
@@ -876,7 +871,8 @@ void RequestGroup::preDownloadProcessing()
 void RequestGroup::postDownloadProcessing
 (std::deque<SharedHandle<RequestGroup> >& groups)
 {
-  _logger->debug("Finding PostDownloadHandler for path %s.", getFilePath().c_str());
+  _logger->debug("Finding PostDownloadHandler for path %s.",
+		 getFirstFilePath().c_str());
   try {
     for(PostDownloadHandlers::const_iterator itr = _postDownloadHandlers.begin();
 	itr != _postDownloadHandlers.end(); ++itr) {
@@ -970,11 +966,6 @@ void RequestGroup::clearPreDowloadHandler()
   _preDownloadHandlers.clear();
 }
 
-void RequestGroup::setDownloadContext(const DownloadContextHandle& downloadContext)
-{
-  _downloadContext = downloadContext;
-}
-
 void RequestGroup::setPieceStorage(const PieceStorageHandle& pieceStorage)
 {
   _pieceStorage = pieceStorage;
@@ -1104,11 +1095,10 @@ void RequestGroup::removeIdenticalURI(const std::string& uri)
 void RequestGroup::reportDownloadFinished()
 {
   _logger->notice(MSG_FILE_DOWNLOAD_COMPLETED,
-		  getFilePath().c_str());
+		  _downloadContext->getBasePath().c_str());
   _uriSelector->resetCounters();
 #ifdef ENABLE_BITTORRENT
-  SharedHandle<BtContext> ctx = dynamic_pointer_cast<BtContext>(_downloadContext);
-  if(!ctx.isNull()) {
+  if(_downloadContext->hasAttribute(bittorrent::BITTORRENT)) {
     TransferStat stat = calculateStat();
     double shareRatio = ((stat.getAllTimeUploadLength()*10)/getCompletedLength())/10.0;
     _logger->notice(MSG_SHARE_RATIO_REPORT,
diff --git a/src/RequestGroup.h b/src/RequestGroup.h
index a8c4c388..3d579929 100644
--- a/src/RequestGroup.h
+++ b/src/RequestGroup.h
@@ -221,7 +221,7 @@ public:
 
   void closeFile();
 
-  std::string getFilePath() const;
+  std::string getFirstFilePath() const;
 
   uint64_t getTotalLength() const;
 
@@ -275,7 +275,10 @@ public:
     return _downloadContext;
   }
 
-  void setDownloadContext(const SharedHandle<DownloadContext>& downloadContext);
+  void setDownloadContext(const SharedHandle<DownloadContext>& downloadContext)
+  {
+    _downloadContext = downloadContext;
+  }
 
   const SharedHandle<PieceStorage>& getPieceStorage() const
   {
diff --git a/src/RequestGroupEntry.cc b/src/RequestGroupEntry.cc
index 01dd9b15..bba57f8b 100644
--- a/src/RequestGroupEntry.cc
+++ b/src/RequestGroupEntry.cc
@@ -35,6 +35,7 @@
 #include "RequestGroupEntry.h"
 #include "RequestGroup.h"
 #include "Command.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/RequestGroupMan.cc b/src/RequestGroupMan.cc
index 41a0f515..9069a4dd 100644
--- a/src/RequestGroupMan.cc
+++ b/src/RequestGroupMan.cc
@@ -274,7 +274,7 @@ private:
     if(!sig.isNull() && !sig->getBody().empty()) {
       // filename of signature file is the path to download file followed by
       // ".sig".
-      std::string signatureFile = group->getFilePath()+".sig";
+      std::string signatureFile = group->getFirstFilePath()+".sig";
       if(sig->save(signatureFile)) {
 	_logger->notice(MSG_SIGNATURE_SAVED, signatureFile.c_str());
       } else {
@@ -637,7 +637,7 @@ std::string RequestGroupMan::formatDownloadResult(const std::string& status, con
     o << "n/a";
   }
   o << "|";
-  const std::deque<SharedHandle<FileEntry> >& fileEntries =
+  const std::vector<SharedHandle<FileEntry> >& fileEntries =
     downloadResult->fileEntries;
   if(downloadResult->result == DownloadResult::FINISHED ||
      downloadResult->numUri == 0) {
@@ -677,7 +677,7 @@ bool RequestGroupMan::isSameFileBeingDownloaded(RequestGroup* requestGroup) cons
   for(RequestGroups::const_iterator itr = _requestGroups.begin();
       itr != _requestGroups.end(); ++itr) {
     if((*itr).get() != requestGroup) {
-      const std::deque<SharedHandle<FileEntry> >& entries =
+      const std::vector<SharedHandle<FileEntry> >& entries =
 	(*itr)->getDownloadContext()->getFileEntries();
       std::transform(entries.begin(), entries.end(),
 		     std::back_inserter(files),
@@ -685,7 +685,7 @@ bool RequestGroupMan::isSameFileBeingDownloaded(RequestGroup* requestGroup) cons
     }
   }
   std::sort(files.begin(), files.end());
-  const std::deque<SharedHandle<FileEntry> >& entries =
+  const std::vector<SharedHandle<FileEntry> >& entries =
     requestGroup->getDownloadContext()->getFileEntries();
   return sameFilePathExists(files.begin(), files.end(),
 			    entries.begin(), entries.end());
diff --git a/src/SeedCheckCommand.cc b/src/SeedCheckCommand.cc
index d005f68e..680f1fdb 100644
--- a/src/SeedCheckCommand.cc
+++ b/src/SeedCheckCommand.cc
@@ -36,23 +36,21 @@
 #include "DownloadEngine.h"
 #include "BtRuntime.h"
 #include "PieceStorage.h"
-#include "BtContext.h"
 #include "Logger.h"
 #include "SeedCriteria.h"
 #include "message.h"
 #include "RequestGroup.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
 SeedCheckCommand::SeedCheckCommand(int cuid,
 				   RequestGroup* requestGroup,
 				   DownloadEngine* e,
-				   const SharedHandle<BtContext>& btContext,
 				   const SeedCriteriaHandle& seedCriteria)
   :Command(cuid),
    _requestGroup(requestGroup),
    e(e),
-   _btContext(btContext),
    seedCriteria(seedCriteria),
    checkStarted(false)
 {
diff --git a/src/SeedCheckCommand.h b/src/SeedCheckCommand.h
index 19f6cf5d..7795e68f 100644
--- a/src/SeedCheckCommand.h
+++ b/src/SeedCheckCommand.h
@@ -43,7 +43,6 @@ namespace aria2 {
 class RequestGroup;
 class DownloadEngine;
 class SeedCriteria;
-class BtContext;
 class BtRuntime;
 class PieceStorage;
 
@@ -52,7 +51,6 @@ class SeedCheckCommand : public Command
 private:
   RequestGroup* _requestGroup;
   DownloadEngine* e;
-  SharedHandle<BtContext> _btContext;
   SharedHandle<PieceStorage> _pieceStorage;
   SharedHandle<BtRuntime> _btRuntime;
   SharedHandle<SeedCriteria> seedCriteria;
@@ -61,7 +59,6 @@ public:
   SeedCheckCommand(int cuid,
 		   RequestGroup* requestGroup,
 		   DownloadEngine* e,
-		   const SharedHandle<BtContext>& btContext,
 		   const SharedHandle<SeedCriteria>& seedCriteria);
 
   virtual ~SeedCheckCommand();
diff --git a/src/SegmentMan.cc b/src/SegmentMan.cc
index 4598e3d3..a3c72a46 100644
--- a/src/SegmentMan.cc
+++ b/src/SegmentMan.cc
@@ -60,7 +60,7 @@ SegmentEntry::SegmentEntry(cuid_t cuid, const SegmentHandle& segment):
 SegmentEntry::~SegmentEntry() {}
 
 SegmentMan::SegmentMan(const Option* option,
-		       const DownloadContextHandle& downloadContext,
+		       const SharedHandle<DownloadContext>& downloadContext,
 		       const PieceStorageHandle& pieceStorage):
   _option(option),
   logger(LogFactory::getInstance()),
@@ -104,7 +104,8 @@ void SegmentMan::setPieceStorage(const PieceStorageHandle& pieceStorage)
   _pieceStorage = pieceStorage;
 }
 
-void SegmentMan::setDownloadContext(const DownloadContextHandle& downloadContext)
+void SegmentMan::setDownloadContext
+(const SharedHandle<DownloadContext>& downloadContext)
 {
   _downloadContext = downloadContext;
 }
diff --git a/src/ShareRatioSeedCriteria.h b/src/ShareRatioSeedCriteria.h
index d09d5219..e4eec635 100644
--- a/src/ShareRatioSeedCriteria.h
+++ b/src/ShareRatioSeedCriteria.h
@@ -36,7 +36,7 @@
 #define _D_SHARE_RATIO_SEED_CRITERIA_H_
 
 #include "SeedCriteria.h"
-#include "BtContext.h"
+#include "DownloadContext.h"
 #include "PeerStorage.h"
 #include "PieceStorage.h"
 
@@ -45,20 +45,21 @@ namespace aria2 {
 class ShareRatioSeedCriteria : public SeedCriteria {
 private:
   double ratio;
-  SharedHandle<BtContext> btContext;
+  SharedHandle<DownloadContext> _downloadContext;
   SharedHandle<PeerStorage> _peerStorage;
   SharedHandle<PieceStorage> _pieceStorage;
 public:
-  ShareRatioSeedCriteria(double ratio, const SharedHandle<BtContext>& btContext)
+  ShareRatioSeedCriteria
+  (double ratio, const SharedHandle<DownloadContext>& downloadContext)
     :ratio(ratio),
-     btContext(btContext) {}
+     _downloadContext(downloadContext) {}
 
   virtual ~ShareRatioSeedCriteria() {}
 
   virtual void reset() {}
 
   virtual bool evaluate() {
-    if(btContext->getTotalLength() == 0) {
+    if(_downloadContext->getTotalLength() == 0) {
       return false;
     }
     TransferStat stat = _peerStorage->calculateStat();
diff --git a/src/SingleFileDownloadContext.cc b/src/SingleFileDownloadContext.cc
deleted file mode 100644
index 1acbb2b1..00000000
--- a/src/SingleFileDownloadContext.cc
+++ /dev/null
@@ -1,108 +0,0 @@
-/* <!-- copyright */
-/*
- * aria2 - The high speed download utility
- *
- * Copyright (C) 2006 Tatsuhiro Tsujikawa
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- *
- * In addition, as a special exception, the copyright holders give
- * permission to link the code of portions of this program with the
- * OpenSSL library under certain conditions as described in each
- * individual source file, and distribute linked combinations
- * including the two.
- * You must obey the GNU General Public License in all respects
- * for all of the code used other than OpenSSL.  If you modify
- * file(s) with this exception, you may extend this exception to your
- * version of the file(s), but you are not obligated to do so.  If you
- * do not wish to do so, delete this exception statement from your
- * version.  If you delete this exception statement from all source
- * files in the program, then also delete it here.
- */
-/* copyright --> */
-#include "SingleFileDownloadContext.h"
-#include "FileEntry.h"
-
-namespace aria2 {
-
-const std::string SingleFileDownloadContext::DEFAULT_FILENAME("index.html");
-
-SingleFileDownloadContext::SingleFileDownloadContext(size_t pieceLength,
-						     uint64_t totalLength,
-						     const std::string& filename,
-						     const std::string& ufilename):
-  _pieceLength(pieceLength),
-  _filename(filename),
-  _ufilename(ufilename),
-  _knowsTotalLength(true)
-{
-  _fileEntries.push_back
-    (SharedHandle<FileEntry>(new FileEntry(filename, totalLength, 0)));
-  updateFileEntry();
-}
-
-void SingleFileDownloadContext::updateFileEntry()
-{
-  const SharedHandle<FileEntry>& fileEntry = _fileEntries.front();
-  if(!_ufilename.empty()) {
-    fileEntry->setPath(_ufilename);
-  } else if(!_filename.empty()) {
-    fileEntry->setPath(_filename);
-  } else {
-    fileEntry->setPath("");
-  }
-}
-
-const std::deque<std::string>&
-SingleFileDownloadContext::getPieceHashes() const
-{
-  return _pieceHashes;
-}
-
-uint64_t SingleFileDownloadContext::getTotalLength() const
-{
-  return _fileEntries.front()->getLength();
-}
-
-bool SingleFileDownloadContext::knowsTotalLength() const
-{
-  return _knowsTotalLength;
-}
-
-size_t SingleFileDownloadContext::getNumPieces() const
-{
-  if(_pieceLength == 0) {
-    return 0;
-  } else {
-    return (_fileEntries.front()->getLength()+_pieceLength-1)/_pieceLength;
-  }
-}
-
-std::string SingleFileDownloadContext::getActualBasePath() const
-{
-  return _fileEntries.front()->getPath();
-}
-
-void SingleFileDownloadContext::setTotalLength(uint64_t totalLength)
-{
-  _fileEntries.front()->setLength(totalLength);
-}
-
-void SingleFileDownloadContext::markTotalLengthIsUnknown()
-{
-  _knowsTotalLength = false;
-}
-
-} // namespace aria2
diff --git a/src/SingleFileDownloadContext.h b/src/SingleFileDownloadContext.h
deleted file mode 100644
index 7f07d9a9..00000000
--- a/src/SingleFileDownloadContext.h
+++ /dev/null
@@ -1,180 +0,0 @@
-/* <!-- copyright */
-/*
- * aria2 - The high speed download utility
- *
- * Copyright (C) 2006 Tatsuhiro Tsujikawa
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- *
- * In addition, as a special exception, the copyright holders give
- * permission to link the code of portions of this program with the
- * OpenSSL library under certain conditions as described in each
- * individual source file, and distribute linked combinations
- * including the two.
- * You must obey the GNU General Public License in all respects
- * for all of the code used other than OpenSSL.  If you modify
- * file(s) with this exception, you may extend this exception to your
- * version of the file(s), but you are not obligated to do so.  If you
- * do not wish to do so, delete this exception statement from your
- * version.  If you delete this exception statement from all source
- * files in the program, then also delete it here.
- */
-/* copyright --> */
-#ifndef _D_SINGLE_FILE_DOWNLOAD_CONTEXT_H_
-#define _D_SINGLE_FILE_DOWNLOAD_CONTEXT_H_
-
-#include "DownloadContext.h"
-
-#include <string>
-#include <deque>
-
-#include "A2STR.h"
-
-namespace aria2 {
-
-class SingleFileDownloadContext:public DownloadContext
-{
-private:
-  size_t _pieceLength;
-  /**
-   * _filename and _ufilename may contains directory path name.  So
-   * /usr/local/aria2c is acceptable here.  These should be complete
-   * file path.
-   */
-  std::string _filename;
-  std::string _ufilename;
-
-  std::string _contentType;
-
-  std::deque<std::string> _pieceHashes;
-  std::string _pieceHashAlgo;
-
-  std::string _checksum;
-  std::string _checksumHashAlgo;
-
-  bool _knowsTotalLength;
-
-  void updateFileEntry();
-public:
-  SingleFileDownloadContext(size_t pieceLength,
-			    uint64_t totalLength,
-			    const std::string& filename,
-			    const std::string& ufilename = A2STR::NIL);
-
-  virtual ~SingleFileDownloadContext() {}
-
-  virtual const std::string& getPieceHash(size_t index) const
-  {
-    if(index < _pieceHashes.size()) {
-      return _pieceHashes[index];
-    } else {
-      return A2STR::NIL;
-    }
-  }
-  
-  virtual const std::deque<std::string>& getPieceHashes() const;
-
-  virtual uint64_t getTotalLength() const;
-
-  virtual bool knowsTotalLength() const;
-
-
-  virtual FILE_MODE getFileMode() const
-  {
-    if(_fileEntries.size() == 1) {
-      return SINGLE;
-    } else {
-      return MULTI;
-    }
-  }
-
-  virtual size_t getPieceLength() const
-  {
-    return _pieceLength;
-  }
-
-  virtual size_t getNumPieces() const;
-
-  virtual std::string getActualBasePath() const;
-
-  virtual const std::string& getPieceHashAlgo() const
-  {
-    return _pieceHashAlgo;
-  }
-
-  const std::string& getChecksumHashAlgo() const
-  {
-    return _checksumHashAlgo;
-  }
-
-  const std::string& getChecksum() const
-  {
-    return _checksum;
-  }
-
-  void setPieceHashes(const std::deque<std::string>& pieceHashes)
-  {
-    _pieceHashes = pieceHashes;
-  }
-  
-  void setChecksumHashAlgo(const std::string& algo)
-  {
-    _checksumHashAlgo = algo;
-  }
-
-  void setChecksum(const std::string& checksum)
-  {
-    _checksum = checksum;
-  }
-
-  void setFilename(const std::string& filename)
-  {
-    _filename = filename;
-    updateFileEntry();
-  }
-
-  void setUFilename(const std::string& ufilename)
-  {
-    _ufilename = ufilename;
-    updateFileEntry();
-  }
-
-  void setTotalLength(uint64_t totalLength);
-
-  void markTotalLengthIsUnknown();
-
-  void setPieceHashAlgo(const std::string& algo)
-  {
-    _pieceHashAlgo = algo;
-  }
-
-  void setContentType(const std::string& contentType)
-  {
-    _contentType = contentType;
-  }
-
-  const std::string& getContentType()
-  {
-    return _contentType;
-  }
-
-  static const std::string DEFAULT_FILENAME;
-};
-
-typedef SharedHandle<SingleFileDownloadContext> SingleFileDownloadContextHandle;
-
-} // namespace aria2
-
-#endif // _D_SINGLE_FILE_DOWNLOAD_CONTEXT_H_
diff --git a/src/SleepCommand.cc b/src/SleepCommand.cc
index 17912215..5fd18604 100644
--- a/src/SleepCommand.cc
+++ b/src/SleepCommand.cc
@@ -35,6 +35,7 @@
 #include "SleepCommand.h"
 #include "RequestGroup.h"
 #include "DownloadEngine.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/StreamCheckIntegrityEntry.cc b/src/StreamCheckIntegrityEntry.cc
index 5a4014c3..39e25393 100644
--- a/src/StreamCheckIntegrityEntry.cc
+++ b/src/StreamCheckIntegrityEntry.cc
@@ -37,6 +37,7 @@
 #include "DownloadEngine.h"
 #include "StreamFileAllocationEntry.h"
 #include "Request.h"
+#include "DownloadContext.h"
 
 namespace aria2 {
 
diff --git a/src/TrackerWatcherCommand.cc b/src/TrackerWatcherCommand.cc
index 87a51c58..dddf163e 100644
--- a/src/TrackerWatcherCommand.cc
+++ b/src/TrackerWatcherCommand.cc
@@ -37,7 +37,6 @@
 #include <sstream>
 
 #include "DownloadEngine.h"
-#include "BtContext.h"
 #include "BtAnnounce.h"
 #include "BtRuntime.h"
 #include "PieceStorage.h"
@@ -45,7 +44,6 @@
 #include "Peer.h"
 #include "prefs.h"
 #include "message.h"
-#include "SingleFileDownloadContext.h"
 #include "ByteArrayDiskWriterFactory.h"
 #include "RecoverableException.h"
 #include "PeerInitiateConnectionCommand.h"
@@ -59,17 +57,16 @@
 #include "SocketCore.h"
 #include "Request.h"
 #include "AnnounceTier.h"
+#include "DownloadContext.h"
+#include "bittorrent_helper.h"
 
 namespace aria2 {
 
-TrackerWatcherCommand::TrackerWatcherCommand(int32_t cuid,
-					     RequestGroup* requestGroup,
-					     DownloadEngine* e,
-					     const BtContextHandle& btContext):
+TrackerWatcherCommand::TrackerWatcherCommand
+(int32_t cuid, RequestGroup* requestGroup, DownloadEngine* e):
   Command(cuid),
   _requestGroup(requestGroup),
-  e(e),
-  _btContext(btContext)
+  e(e)
 {
   _requestGroup->increaseNumCommand();
 }
@@ -162,12 +159,8 @@ void TrackerWatcherCommand::processTrackerResponse
     }
     peer->usedBy(e->newCUID());
     PeerInitiateConnectionCommand* command =
-      new PeerInitiateConnectionCommand(peer->usedBy(),
-					_requestGroup,
-					peer,
-					e,
-					_btContext,
-					_btRuntime);
+      new PeerInitiateConnectionCommand
+      (peer->usedBy(), _requestGroup, peer, e, _btRuntime);
     command->setPeerStorage(_peerStorage);
     command->setPieceStorage(_pieceStorage);
     e->commands.push_back(command);
@@ -185,15 +178,17 @@ RequestGroupHandle TrackerWatcherCommand::createAnnounce() {
 }
 
 static bool backupTrackerIsAvailable
-(const std::deque<SharedHandle<AnnounceTier> >& announceTiers)
+(const SharedHandle<DownloadContext>& context)
 {
-  if(announceTiers.size() >= 2) {
+  const BDE& announceList =
+    context->getAttribute(bittorrent::BITTORRENT)[bittorrent::ANNOUNCE_LIST];
+  if(announceList.size() >= 2) {
     return true;
   }
-  if(announceTiers.empty()) {
+  if(announceList.empty()) {
     return false;
   }
-  if(announceTiers[0]->urls.size() >= 2) {
+  if(announceList[0].size() >= 2) {
     return true;
   } else {
     return false;
@@ -208,7 +203,7 @@ TrackerWatcherCommand::createRequestGroup(const std::string& uri)
   RequestGroupHandle rg(new RequestGroup(getOption(), uris));
   // If backup tracker is available, only try 2 times for each tracker
   // and if they all fails, then try next one.
-  if(backupTrackerIsAvailable(_btContext->getAnnounceTiers())) {
+  if(backupTrackerIsAvailable(_requestGroup->getDownloadContext())) {
     logger->debug("This is multi-tracker announce.");
     rg->getOption()->put(PREF_MAX_TRIES, "2");
   } else {
@@ -217,11 +212,10 @@ TrackerWatcherCommand::createRequestGroup(const std::string& uri)
   }
 
   static const std::string TRACKER_ANNOUNCE_FILE("[tracker.announce]");
-  SingleFileDownloadContextHandle dctx
-    (new SingleFileDownloadContext(getOption()->getAsInt(PREF_SEGMENT_SIZE),
-				   0,
-				   A2STR::NIL,
-				   TRACKER_ANNOUNCE_FILE));
+  SharedHandle<DownloadContext> dctx
+    (new DownloadContext(getOption()->getAsInt(PREF_SEGMENT_SIZE),
+			 0,
+			 TRACKER_ANNOUNCE_FILE));
   dctx->setDir(A2STR::NIL);
   dctx->getFileEntries().front()->setUris(uris);
   rg->setDownloadContext(dctx);
diff --git a/src/TrackerWatcherCommand.h b/src/TrackerWatcherCommand.h
index 9c7c2417..7ec0c03f 100644
--- a/src/TrackerWatcherCommand.h
+++ b/src/TrackerWatcherCommand.h
@@ -42,7 +42,6 @@ namespace aria2 {
 
 class DownloadEngine;
 class RequestGroup;
-class BtContext;
 class PeerStorage;
 class PieceStorage;
 class BtRuntime;
@@ -56,8 +55,6 @@ private:
 
   DownloadEngine* e;
 
-  SharedHandle<BtContext> _btContext;
-
   SharedHandle<PeerStorage> _peerStorage;
 
   SharedHandle<PieceStorage> _pieceStorage;
@@ -81,8 +78,7 @@ private:
 public:
   TrackerWatcherCommand(int32_t cuid,
 			RequestGroup* requestGroup,
-			DownloadEngine* e,
-			const SharedHandle<BtContext>& btContext);
+			DownloadEngine* e);
 
   virtual ~TrackerWatcherCommand();
 
diff --git a/src/UnknownLengthPieceStorage.cc b/src/UnknownLengthPieceStorage.cc
index 369767c7..878fff93 100644
--- a/src/UnknownLengthPieceStorage.cc
+++ b/src/UnknownLengthPieceStorage.cc
@@ -46,8 +46,9 @@
 
 namespace aria2 {
 
-UnknownLengthPieceStorage::UnknownLengthPieceStorage(const DownloadContextHandle& downloadContext,
-						     const Option* option):
+UnknownLengthPieceStorage::UnknownLengthPieceStorage
+(const SharedHandle<DownloadContext>& downloadContext,
+ const Option* option):
   _downloadContext(downloadContext),
   _option(option),
   _diskWriterFactory(new DefaultDiskWriterFactory()),
@@ -60,7 +61,8 @@ void UnknownLengthPieceStorage::initStorage()
 {
   DirectDiskAdaptorHandle directDiskAdaptor(new DirectDiskAdaptor());
   directDiskAdaptor->setTotalLength(_downloadContext->getTotalLength());
-  directDiskAdaptor->setFileEntries(_downloadContext->getFileEntries());
+  directDiskAdaptor->setFileEntries(_downloadContext->getFileEntries().begin(),
+				    _downloadContext->getFileEntries().end());
 
   DiskWriterHandle writer =
     _diskWriterFactory->newDiskWriter(directDiskAdaptor->getFilePath());
diff --git a/src/Util.cc b/src/Util.cc
index c2cabda1..0ade0084 100644
--- a/src/Util.cc
+++ b/src/Util.cc
@@ -43,7 +43,6 @@
 #include <cstring>
 #include <cstdio>
 #include <cstdlib>
-#include <iomanip>
 #include <sstream>
 #include <ostream>
 #include <algorithm>
@@ -709,20 +708,6 @@ time_t Util::httpGMT(const std::string& httpStdTime)
   return thetime;
 }
 
-void Util::toStream(std::ostream& os, const FileEntries& fileEntries)
-{
-  os << _("Files:") << "\n";
-  os << "idx|path/length" << "\n";
-  os << "===+===========================================================================" << "\n";
-  int32_t count = 1;
-  for(FileEntries::const_iterator itr = fileEntries.begin();
-      itr != fileEntries.end(); ++count, ++itr) {
-    os << std::setw(3) << count << "|" << (*itr)->getPath() << "\n";
-    os << "   |" << Util::abbrevSize((*itr)->getLength()) << "B" << "\n";
-    os << "---+---------------------------------------------------------------------------" << "\n";
-  }
-}
-
 void Util::sleep(long seconds) {
 #ifdef HAVE_SLEEP
   ::sleep(seconds);
diff --git a/src/Util.h b/src/Util.h
index fd5da150..6a54de02 100644
--- a/src/Util.h
+++ b/src/Util.h
@@ -43,8 +43,10 @@
 #include <utility>
 #include <deque>
 #include <iosfwd>
+#include <ostream>
 #include <numeric>
 #include <map>
+#include <iomanip>
 
 #include "SharedHandle.h"
 #include "IntSequence.h"
@@ -243,8 +245,20 @@ public:
    */
   static time_t httpGMT(const std::string& httpTimeFormat);
 
-  static void toStream(std::ostream& os,
-		       const std::deque<SharedHandle<FileEntry> >& entries);
+  template<typename InputIterator>
+  static void toStream
+  (InputIterator first, InputIterator last, std::ostream& os)
+  {
+    os << _("Files:") << "\n";
+    os << "idx|path/length" << "\n";
+    os << "===+===========================================================================" << "\n";
+    int32_t count = 1;
+    for(; first != last; ++first, ++count) {
+    os << std::setw(3) << count << "|" << (*first)->getPath() << "\n";
+    os << "   |" << Util::abbrevSize((*first)->getLength()) << "B" << "\n";
+    os << "---+---------------------------------------------------------------------------" << "\n";
+    }
+  }
 
   static void sleep(long seconds);
 
diff --git a/src/XmlRpcMethodImpl.cc b/src/XmlRpcMethodImpl.cc
index 8bc629a2..954369c2 100644
--- a/src/XmlRpcMethodImpl.cc
+++ b/src/XmlRpcMethodImpl.cc
@@ -51,17 +51,20 @@
 #include "StringFormat.h"
 #include "XmlRpcRequest.h"
 #include "PieceStorage.h"
-#include "PeerStorage.h"
-#include "BtContext.h"
-#include "BtRegistry.h"
-#include "Peer.h"
+#include "DownloadContext.h"
 #include "DiskAdaptor.h"
 #include "FileEntry.h"
 #include "BtProgressInfoFile.h"
-#include "BtRuntime.h"
-#include "BtAnnounce.h"
 #include "prefs.h"
 #include "message.h"
+#ifdef ENABLE_BITTORRENT
+# include "bittorrent_helper.h"
+# include "BtRegistry.h"
+# include "PeerStorage.h"
+# include "Peer.h"
+# include "BtRuntime.h"
+# include "BtAnnounce.h"
+#endif // ENABLE_BITTORRENT
 
 namespace aria2 {
 
@@ -286,13 +289,12 @@ static void gatherProgressCommon
 
 #ifdef ENABLE_BITTORRENT
 static void gatherProgressBitTorrent
-(BDE& entryDict, const SharedHandle<BtContext>& btctx,
- const SharedHandle<BtRegistry>& btreg)
+(BDE& entryDict, const BDE& torrentAttrs, const SharedHandle<BtRegistry>& btreg)
 {
-  entryDict["infoHash"] = btctx->getInfoHashAsString();
+  const std::string& infoHash = torrentAttrs[bittorrent::INFO_HASH].s();
+  entryDict["infoHash"] = Util::toHex(infoHash);
 
-  SharedHandle<PeerStorage> peerStorage =
-    btreg->get(btctx->getInfoHashAsString())._peerStorage;
+  SharedHandle<PeerStorage> peerStorage = btreg->get(infoHash)._peerStorage;
   assert(!peerStorage.isNull());
 
   std::deque<SharedHandle<Peer> > peers;
@@ -329,11 +331,11 @@ static void gatherProgress
 {
   gatherProgressCommon(entryDict, group);
 #ifdef ENABLE_BITTORRENT
-  SharedHandle<BtContext> btctx =
-    dynamic_pointer_cast<BtContext>(group->getDownloadContext());
-  if(!btctx.isNull()) {
+  if(group->getDownloadContext()->hasAttribute(bittorrent::BITTORRENT)) {
+    const BDE& torrentAttrs =
+      group->getDownloadContext()->getAttribute(bittorrent::BITTORRENT);
     SharedHandle<BtRegistry> btreg = e->getBtRegistry();
-    gatherProgressBitTorrent(entryDict, btctx, btreg);
+    gatherProgressBitTorrent(entryDict, torrentAttrs, btreg);
   }
 #endif // ENABLE_BITTORRENT
 }
@@ -400,9 +402,9 @@ BDE GetFilesXmlRpcMethod::process
       createFileEntry(files, dr->fileEntries.begin(), dr->fileEntries.end());
     }
   } else {
-    const std::deque<SharedHandle<FileEntry> >& fileEntries =
-      group->getDownloadContext()->getFileEntries();
-    createFileEntry(files, fileEntries.begin(), fileEntries.end());
+    createFileEntry(files,
+		    group->getDownloadContext()->getFileEntries().begin(),
+		    group->getDownloadContext()->getFileEntries().end());
   }
   return files;
 }
@@ -455,12 +457,12 @@ BDE GetPeersXmlRpcMethod::process
       (StringFormat("No peer data is available for GID#%d", gid).str());
   }
   BDE peers = BDE::list();
-  SharedHandle<BtContext> btctx =
-    dynamic_pointer_cast<BtContext>(group->getDownloadContext());
-  if(!btctx.isNull()) {
+  if(group->getDownloadContext()->hasAttribute(bittorrent::BITTORRENT)) {
     SharedHandle<BtRegistry> btreg = e->getBtRegistry();
+    const BDE& torrentAttrs =
+      group->getDownloadContext()->getAttribute(bittorrent::BITTORRENT);
     SharedHandle<PeerStorage> peerStorage =
-      btreg->get(btctx->getInfoHashAsString())._peerStorage;
+      btreg->get(torrentAttrs[bittorrent::INFO_HASH].s())._peerStorage;
     assert(!peerStorage.isNull());
     BDE entry = BDE::dict();
     gatherPeer(peers, peerStorage);
diff --git a/src/bittorrent_helper.cc b/src/bittorrent_helper.cc
new file mode 100644
index 00000000..cb3be528
--- /dev/null
+++ b/src/bittorrent_helper.cc
@@ -0,0 +1,529 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * Copyright (C) 2009 Tatsuhiro Tsujikawa
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+#include "bittorrent_helper.h"
+
+#include <algorithm>
+#include <deque>
+
+#include "DownloadContext.h"
+#include "Randomizer.h"
+#include "bencode.h"
+#include "Util.h"
+#include "DlAbortEx.h"
+#include "message.h"
+#include "StringFormat.h"
+#include "BtConstants.h"
+#include "messageDigest.h"
+#include "MessageDigestHelper.h"
+#include "PeerMessageUtil.h"
+#include "SimpleRandomizer.h"
+
+namespace aria2 {
+
+namespace bittorrent {
+
+static const std::string C_NAME("name");
+
+static const std::string C_NAME_UTF8("name.utf-8");
+
+static const std::string C_FILES("files");
+
+static const std::string C_LENGTH("length");
+
+static const std::string C_PATH("path");
+
+static const std::string C_PATH_UTF8("path.utf-8");
+
+static const std::string C_INFO("info");
+
+static const std::string C_PIECES("pieces");
+
+static const std::string C_PIECE_LENGTH("piece length");
+
+static const std::string C_PRIVATE("private");
+
+static const std::string C_URL_LIST("url-list");
+
+static const std::string C_ANNOUNCE("announce");
+
+static const std::string C_ANNOUNCE_LIST("announce-list");
+
+static const std::string C_NODES("nodes");
+
+static const std::string DEFAULT_PEER_ID_PREFIX("-aria2-");
+
+const std::string INFO_HASH("infoHash");
+
+const std::string MODE("mode");
+
+const std::string PRIVATE("private");
+
+const std::string ANNOUNCE_LIST("announceList");
+
+const std::string NODES("nodes");
+
+const std::string HOSTNAME("hostname");
+
+const std::string PORT("port");
+
+const std::string NAME("name");
+
+const std::string BITTORRENT("bittorrent");
+
+const std::string MULTI("multi");
+
+const std::string SINGLE("single");
+
+static void extractPieceHash(const SharedHandle<DownloadContext>& ctx,
+			     const std::string& hashData,
+			     size_t hashLength,
+			     size_t numPieces)
+{
+  std::vector<std::string> pieceHashes;
+  for(size_t i = 0; i < numPieces; ++i) {
+    pieceHashes.push_back(Util::toHex(hashData.data()+i*hashLength,
+				      hashLength));
+  }
+  ctx->setPieceHashes(pieceHashes.begin(), pieceHashes.end());
+  ctx->setPieceHashAlgo(MessageDigestContext::SHA1);
+}
+
+static void extractUrlList(std::vector<std::string>& uris, const BDE& bde)
+{
+  if(bde.isList()) {
+    for(BDE::List::const_iterator itr = bde.listBegin();
+	itr != bde.listEnd(); ++itr) {
+      if((*itr).isString()) {
+	uris.push_back((*itr).s());
+      }
+    }
+  } else if(bde.isString()) {
+    uris.push_back(bde.s());
+  }
+}
+
+static void extractFileEntries
+(const SharedHandle<DownloadContext>& ctx,
+ BDE& torrent,
+ const BDE& infoDict,
+ const std::string& defaultName,
+ const std::string& overrideName,
+ const std::vector<std::string>& urlList)
+{
+  std::string name;
+  if(overrideName.empty()) {
+    std::string nameKey;
+    if(infoDict.containsKey(C_NAME_UTF8)) {
+      nameKey = C_NAME_UTF8;
+    } else {
+      nameKey = C_NAME;
+    }
+    const BDE& nameData = infoDict[nameKey];
+    if(nameData.isString()) {
+      // Slice path by '/' just in case nasty ".." is included in name
+      std::deque<std::string> pathelems;
+      Util::slice(pathelems, nameData.s(), '/');
+      name = Util::joinPath(pathelems.begin(), pathelems.end());
+      torrent[NAME] = nameData.s();
+    } else {
+      name = strconcat(File(defaultName).getBasename(), ".file");
+      torrent[NAME] = name;
+    }
+  } else {
+    name = overrideName;
+    torrent[NAME] = name;
+  }
+
+  const BDE& filesList = infoDict[C_FILES];
+  std::vector<SharedHandle<FileEntry> > fileEntries;
+  if(filesList.isList()) {
+    uint64_t length = 0;
+    off_t offset = 0;
+    // multi-file mode
+    torrent[MODE] = MULTI;
+    for(BDE::List::const_iterator itr = filesList.listBegin();
+	itr != filesList.listEnd(); ++itr) {
+      const BDE& fileDict = *itr;
+      if(!fileDict.isDict()) {
+	continue;
+      }
+      const BDE& fileLengthData = fileDict[C_LENGTH];
+      if(!fileLengthData.isInteger()) {
+	throw DL_ABORT_EX(StringFormat(MSG_MISSING_BT_INFO,
+				       C_LENGTH.c_str()).str());
+      }
+      length += fileLengthData.i();
+
+      std::string pathKey;
+      if(fileDict.containsKey(C_PATH_UTF8)) {
+	pathKey = C_PATH_UTF8;
+      } else {
+	pathKey = C_PATH;
+      }
+      const BDE& pathList = fileDict[pathKey];
+      if(!pathList.isList() || pathList.empty()) {
+	throw DL_ABORT_EX("Path is empty.");
+      }
+      
+      std::vector<std::string> pathelem(pathList.size());
+      std::transform(pathList.listBegin(), pathList.listEnd(), pathelem.begin(),
+		     std::mem_fun_ref(&BDE::s));
+      std::string path = name;
+      strappend(path, "/", Util::joinPath(pathelem.begin(), pathelem.end()));
+      // Split path with '/' again because each pathList element can
+      // contain "/" inside.
+      std::deque<std::string> elements;
+      Util::slice(elements, path, '/');
+      path = Util::joinPath(elements.begin(), elements.end());
+
+      std::deque<std::string> uris;
+      std::transform(urlList.begin(), urlList.end(), std::back_inserter(uris),
+		     std::bind2nd(std::plus<std::string>(), "/"+path));
+      SharedHandle<FileEntry> fileEntry
+	(new FileEntry(strconcat(ctx->getDir(), "/", path),
+		       fileLengthData.i(),
+		       offset, uris));
+      fileEntries.push_back(fileEntry);
+      offset += fileEntry->getLength();
+    }
+  } else {
+    // single-file mode;
+    torrent[MODE] = SINGLE;
+    const BDE& lengthData = infoDict[C_LENGTH];
+    if(!lengthData.isInteger()) {
+	throw DL_ABORT_EX(StringFormat(MSG_MISSING_BT_INFO,
+				       C_LENGTH.c_str()).str());      
+    }
+    uint64_t totalLength = lengthData.i();
+
+    // For each uri in urlList, if it ends with '/', then
+    // concatenate name to it. Specification just says so.
+    std::deque<std::string> uris;
+    for(std::vector<std::string>::const_iterator i = urlList.begin();
+	i != urlList.end(); ++i) {
+      if(Util::endsWith(*i, "/")) {
+	uris.push_back((*i)+name);
+      } else {
+	uris.push_back(*i);
+      }
+    }
+
+    SharedHandle<FileEntry> fileEntry
+      (new FileEntry(strconcat(ctx->getDir(), "/", name),totalLength, 0,
+		     uris));
+    fileEntries.push_back(fileEntry);
+  }
+  ctx->setFileEntries(fileEntries.begin(), fileEntries.end());
+  if(torrent[MODE].s() == MULTI) {
+    ctx->setBasePath(strconcat(ctx->getDir(), "/", name));
+  }
+}
+
+static void extractAnnounce(BDE& torrent, const BDE& rootDict)
+{
+  const BDE& announceList = rootDict[C_ANNOUNCE_LIST];
+  if(announceList.isList()) {
+    torrent[ANNOUNCE_LIST] = announceList;
+  } else {
+    const BDE& announce = rootDict[C_ANNOUNCE];
+    BDE announceList = BDE::list();
+    if(announce.isString()) {
+      announceList << BDE::list();
+      announceList[0] << announce;
+    }
+    torrent[ANNOUNCE_LIST] = announceList;
+  }
+}
+
+static void extractNodes(BDE& torrent, const BDE& nodesList)
+{
+  BDE nodes = BDE::list();
+  if(nodesList.isList()) {
+    for(BDE::List::const_iterator i = nodesList.listBegin();
+	i != nodesList.listEnd(); ++i) {
+      const BDE& addrPairList = (*i);
+      if(!addrPairList.isList() || addrPairList.size() != 2) {
+	continue;
+      }
+      const BDE& hostname = addrPairList[0];
+      if(!hostname.isString()) {
+	continue;
+      }
+      if(Util::trim(hostname.s()).empty()) {
+	continue;
+      }
+      const BDE& port = addrPairList[1];
+      if(!port.isInteger() || !(0 < port.i() && port.i() < 65536)) {
+	continue;
+      }
+      BDE node = BDE::dict();
+      node[HOSTNAME] = hostname;
+      node[PORT] = port;
+      nodes << node;
+    }
+  }
+  torrent[NODES] = nodes;
+}
+
+static void processRootDictionary
+(const SharedHandle<DownloadContext>& ctx,
+ const BDE& rootDict,
+ const std::string& defaultName,
+ const std::string& overrideName)
+{
+  if(!rootDict.isDict()) {
+    throw DL_ABORT_EX("torrent file does not contain a root dictionary.");
+  }
+  const BDE& infoDict = rootDict[C_INFO];
+  if(!infoDict.isDict()) {
+    throw DL_ABORT_EX(StringFormat(MSG_MISSING_BT_INFO,
+				   C_INFO.c_str()).str());
+  }
+  BDE torrent = BDE::dict();
+
+  // retrieve infoHash
+  std::string encodedInfoDict = bencode::encode(infoDict);
+  unsigned char infoHash[INFO_HASH_LENGTH];
+  MessageDigestHelper::digest(infoHash, INFO_HASH_LENGTH,
+			      MessageDigestContext::SHA1,
+			      encodedInfoDict.data(),
+			      encodedInfoDict.size());
+  torrent[INFO_HASH] = std::string(&infoHash[0], &infoHash[INFO_HASH_LENGTH]);
+
+  // calculate the number of pieces
+  const BDE& piecesData = infoDict[C_PIECES];
+  if(!piecesData.isString()) {
+    throw DL_ABORT_EX(StringFormat(MSG_MISSING_BT_INFO,
+				   C_PIECES.c_str()).str());
+  }
+  if(piecesData.s().empty()) {
+    throw DL_ABORT_EX("The length of piece hash is 0.");
+  }
+  size_t numPieces = piecesData.s().size()/PIECE_HASH_LENGTH;
+  if(numPieces == 0) {
+    throw DL_ABORT_EX("The number of pieces is 0.");
+  }
+  // retrieve piece length
+  const BDE& pieceLengthData = infoDict[C_PIECE_LENGTH];
+  if(!pieceLengthData.isInteger()) {
+    throw DL_ABORT_EX(StringFormat(MSG_MISSING_BT_INFO,
+				   C_PIECE_LENGTH.c_str()).str());
+  }
+  size_t pieceLength = pieceLengthData.i();
+  ctx->setPieceLength(pieceLength);
+  // retrieve piece hashes
+  extractPieceHash(ctx, piecesData.s(), PIECE_HASH_LENGTH, numPieces);
+  // private flag
+  const BDE& privateData = infoDict[C_PRIVATE];
+  int privatefg = 0;
+  if(privateData.isInteger()) {
+    if(privateData.i() == 1) {
+      privatefg = 1;
+    }
+  }
+  torrent[PRIVATE] = BDE((int64_t)privatefg);
+  // retrieve uri-list.
+  // This implemantation obeys HTTP-Seeding specification:
+  // see http://www.getright.com/seedtorrent.html
+  std::vector<std::string> urlList;
+  extractUrlList(urlList, rootDict[C_URL_LIST]);
+
+  // retrieve file entries
+  extractFileEntries(ctx, torrent, infoDict, defaultName, overrideName, urlList);
+  if((ctx->getTotalLength()+pieceLength-1)/pieceLength != numPieces) {
+    throw DL_ABORT_EX("Too few/many piece hash.");
+  }
+  // retrieve announce
+  extractAnnounce(torrent, rootDict);
+  // retrieve nodes
+  extractNodes(torrent, rootDict[C_NODES]);
+
+  ctx->setAttribute(BITTORRENT, torrent);
+}
+
+void load(const std::string& torrentFile,
+	  const SharedHandle<DownloadContext>& ctx,
+	  const std::string& overrideName)
+{
+  processRootDictionary(ctx,
+			bencode::decodeFromFile(torrentFile),
+			torrentFile,
+			overrideName);
+
+}
+
+void loadFromMemory(const unsigned char* content,
+		    size_t length,
+		    const SharedHandle<DownloadContext>& ctx,
+		    const std::string& defaultName,
+		    const std::string& overrideName)
+{
+  processRootDictionary(ctx,
+			bencode::decode(content, length),
+			defaultName,
+			overrideName);
+}
+
+void loadFromMemory(const std::string& context,
+		    const SharedHandle<DownloadContext>& ctx,
+		    const std::string& defaultName,
+		    const std::string& overrideName)
+{
+  processRootDictionary
+    (ctx,
+     bencode::decode(reinterpret_cast<const unsigned char*>(context.c_str()),
+		     context.size()),
+     defaultName, overrideName);
+}
+
+const unsigned char*
+getInfoHash(const SharedHandle<DownloadContext>& downloadContext)
+{
+  return downloadContext->getAttribute(BITTORRENT)[INFO_HASH].uc();
+}
+
+std::string
+getInfoHashString(const SharedHandle<DownloadContext>& downloadContext)
+{
+  return Util::toHex(downloadContext->getAttribute(BITTORRENT)[INFO_HASH].s());
+}
+
+void print(std::ostream& o, const SharedHandle<DownloadContext>& dctx)
+{
+  const BDE& torrentAttrs = dctx->getAttribute(BITTORRENT);
+  o << "*** BitTorrent File Information ***" << "\n";
+  o << "Mode: " << torrentAttrs[MODE].s() << "\n";
+  o << "Announce:" << "\n";
+  const BDE& announceList = torrentAttrs[ANNOUNCE_LIST];
+  for(BDE::List::const_iterator tieritr = announceList.listBegin();
+      tieritr != announceList.listEnd(); ++tieritr) {
+    if(!(*tieritr).isList()) {
+      continue;
+    }
+    for(BDE::List::const_iterator i = (*tieritr).listBegin();
+	i != (*tieritr).listEnd(); ++i) {
+      o << " " << (*i).s();
+    }
+    o << "\n";
+  }
+  o << "Info Hash: " << Util::toHex(torrentAttrs[INFO_HASH].s()) << "\n";
+  o << "Piece Length: " << Util::abbrevSize(dctx->getPieceLength()) << "B\n";
+  o << "The Number of Pieces: " << dctx->getNumPieces() << "\n";
+  o << "Total Length: " << Util::abbrevSize(dctx->getTotalLength()) << "B\n";
+  o << "Name: " << torrentAttrs[NAME].s() << "\n";
+  Util::toStream(dctx->getFileEntries().begin(), dctx->getFileEntries().end(), o);
+}
+
+void computeFastSet
+(std::vector<size_t>& fastSet, const std::string& ipaddr,
+ size_t numPieces, const unsigned char* infoHash, size_t fastSetSize)
+{
+  unsigned char compact[6];
+  if(!PeerMessageUtil::createcompact(compact, ipaddr, 0)) {
+    return;
+  }
+  if(numPieces < fastSetSize) {
+    fastSetSize = numPieces;
+  }
+  unsigned char tx[24];
+  memcpy(tx, compact, 4);
+  if((tx[0] & 0x80) == 0 || (tx[0] & 0x40) == 0) {
+    tx[2] = 0x00;
+    tx[3] = 0x00;
+  } else {
+    tx[3] = 0x00;
+  }
+  memcpy(tx+4, infoHash, 20);
+  unsigned char x[20];
+  MessageDigestHelper::digest(x, sizeof(x), MessageDigestContext::SHA1, tx, 24);
+  while(fastSet.size() < fastSetSize) {
+    for(size_t i = 0; i < 5 && fastSet.size() < fastSetSize; ++i) {
+      size_t j = i*4;
+      uint32_t ny;
+      memcpy(&ny, x+j, 4);
+      uint32_t y = ntohl(ny);
+      size_t index = y%numPieces;
+      if(std::find(fastSet.begin(), fastSet.end(), index) == fastSet.end()) {
+	fastSet.push_back(index);
+      }
+    }
+    unsigned char temp[20];
+    MessageDigestHelper::digest(temp, sizeof(temp), MessageDigestContext::SHA1, x, sizeof(x));
+    memcpy(x, temp, sizeof(x));
+  }
+}
+
+std::string generatePeerId
+(const std::string& peerIdPrefix, const SharedHandle<Randomizer>& randomizer)
+{
+  std::string peerId = peerIdPrefix;
+  peerId += Util::randomAlpha(20-peerIdPrefix.size(), randomizer);
+  if(peerId.size() > 20) {
+    peerId.erase(20);
+  }
+  return peerId;
+}
+
+static std::string peerId;
+
+const std::string& generateStaticPeerId
+(const std::string& peerIdPrefix, const SharedHandle<Randomizer>& randomizer)
+{
+  if(peerId.empty()) {
+    peerId = generatePeerId(peerIdPrefix, randomizer);
+  }
+  return peerId;
+}
+
+void setStaticPeerId(const std::string& newPeerId)
+{
+  peerId = newPeerId;
+}
+
+// If PeerID is not generated, it is created with default peerIdPrefix
+// (-aria2-) and SimpleRandomizer.
+const unsigned char* getStaticPeerId()
+{
+  if(peerId.empty()) {
+    return
+      reinterpret_cast<const unsigned char*>(generateStaticPeerId(DEFAULT_PEER_ID_PREFIX, SimpleRandomizer::getInstance()).data());
+  } else {
+    return reinterpret_cast<const unsigned char*>(peerId.data());
+  }
+}
+
+} // namespace bittorrent
+
+} // namespace aria2
diff --git a/src/bittorrent_helper.h b/src/bittorrent_helper.h
new file mode 100644
index 00000000..99db7d9a
--- /dev/null
+++ b/src/bittorrent_helper.h
@@ -0,0 +1,132 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * Copyright (C) 2009 Tatsuhiro Tsujikawa
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+#ifndef _D_BITTORRENT_HELPER_H_
+#define _D_BITTORRENT_HELPER_H_
+
+#include "common.h"
+
+#include <string>
+#include <vector>
+
+#include "SharedHandle.h"
+#include "AnnounceTier.h"
+#include "BDE.h"
+#include "Util.h"
+
+namespace aria2 {
+
+class DownloadContext;
+class Randomizer;
+
+namespace bittorrent {
+
+extern const std::string INFO_HASH;
+
+extern const std::string MODE;
+
+extern const std::string PRIVATE;
+
+extern const std::string ANNOUNCE_LIST;
+
+extern const std::string NODES;
+
+extern const std::string HOSTNAME;
+
+extern const std::string PORT;
+
+extern const std::string NAME;
+
+extern const std::string SINGLE;
+
+extern const std::string MULTI;
+
+extern const std::string BITTORRENT;
+
+void load(const std::string& torrentFile,
+	  const SharedHandle<DownloadContext>& ctx,
+	  const std::string& overrideName = "");
+
+void loadFromMemory(const unsigned char* content, size_t length,
+		    const SharedHandle<DownloadContext>& ctx,
+		    const std::string& defaultName,
+		    const std::string& overrideName = "");
+
+void loadFromMemory(const std::string& context,
+		    const SharedHandle<DownloadContext>& ctx,
+		    const std::string& defaultName,
+		    const std::string& overrideName = "");
+
+// Generates Peer ID. BitTorrent specification says Peer ID is 20-byte
+// length.  This function uses peerIdPrefix as a Peer ID and it is
+// less than 20bytes, random bytes are generated and appened to it. If
+// peerIdPrefix is larger than 20bytes, first 20bytes are used.
+std::string generatePeerId
+(const std::string& peerIdPrefix, const SharedHandle<Randomizer>& randomizer);
+
+// Generates Peer ID and stores it in static variable. This function
+// uses generatePeerId(peerIdPrefix, randomizer) to produce Peer ID.
+const std::string& generateStaticPeerId
+(const std::string& peerIdPrefix, const SharedHandle<Randomizer>& randomizer);
+
+// Returns Peer ID statically stored by generateStaticPeerId().  If
+// Peer ID is not stored yet, this function calls
+// generateStaticPeerId("-aria2-", randomizer)
+const unsigned char* getStaticPeerId();
+
+// Set newPeerId as a static Peer ID. newPeerId must be 20-byte
+// length.
+void setStaticPeerId(const std::string& newPeerId);
+
+// Computes fast set index and stores them in fastset.
+void computeFastSet
+(std::vector<size_t>& fastSet, const std::string& ipaddr,
+ size_t numPieces, const unsigned char* infoHash, size_t fastSetSize);
+
+// Writes the detailed information about torrent loaded in dctx.
+void print(std::ostream& o, const SharedHandle<DownloadContext>& dctx);
+
+// Returns the value associated with INFO_HASH key in BITTORRENT
+// attribute.
+const unsigned char*
+getInfoHash(const SharedHandle<DownloadContext>& downloadContext);
+
+std::string
+getInfoHashString(const SharedHandle<DownloadContext>& downloadContext);
+
+} // namespace bittorrent
+
+} // namespace aria2
+
+#endif // _D_BITTORRENT_HELPER_H_
diff --git a/src/download_helper.cc b/src/download_helper.cc
index b232f33d..baabf94e 100644
--- a/src/download_helper.cc
+++ b/src/download_helper.cc
@@ -48,12 +48,11 @@
 #include "ParameterizedStringParser.h"
 #include "PStringBuildVisitor.h"
 #include "UriListParser.h"
-#include "SingleFileDownloadContext.h"
+#include "DownloadContext.h"
 #include "RecoverableException.h"
 #include "DlAbortEx.h"
 #include "message.h"
 #include "StringFormat.h"
-#include "DefaultBtContext.h"
 #include "FileEntry.h"
 #include "LogFactory.h"
 #include "File.h"
@@ -62,6 +61,9 @@
 #include "OptionHandler.h"
 #include "ByteArrayDiskWriter.h"
 #include "a2functional.h"
+#ifdef ENABLE_BITTORRENT
+# include "bittorrent_helper.h"
+#endif // ENABLE_BITTORRENT
 
 namespace aria2 {
 
@@ -178,16 +180,14 @@ static SharedHandle<RequestGroup> createRequestGroup
  bool useOutOption = false)
 {
   SharedHandle<RequestGroup> rg(new RequestGroup(option, uris));
-  SharedHandle<SingleFileDownloadContext> dctx
-    (new SingleFileDownloadContext
+  SharedHandle<DownloadContext> dctx
+    (new DownloadContext
      (option->getAsInt(PREF_SEGMENT_SIZE),
       0,
-      A2STR::NIL,
       useOutOption&&!option->blank(PREF_OUT)?
       strconcat(option->get(PREF_DIR), "/", option->get(PREF_OUT)):A2STR::NIL));
-
   dctx->setDir(option->get(PREF_DIR));
-  dctx->getFileEntries().front()->setUris(uris);
+  dctx->getFirstFileEntry()->setUris(uris);
   rg->setDownloadContext(dctx);
   return rg;
 }
@@ -202,28 +202,26 @@ createBtRequestGroup(const std::string& torrentFilePath,
 		     const std::string& torrentData = "")
 {
   SharedHandle<RequestGroup> rg(new RequestGroup(option, auxUris));
-  SharedHandle<DefaultBtContext> btContext(new DefaultBtContext());
-  btContext->setDir(option->get(PREF_DIR));
+  SharedHandle<DownloadContext> dctx(new DownloadContext());
+  dctx->setDir(option->get(PREF_DIR));
   if(torrentData.empty()) {
-    btContext->load(torrentFilePath);// may throw exception
+    bittorrent::load(torrentFilePath, dctx);// may throw exception
   } else {
-    btContext->loadFromMemory(torrentData, "default"); // may throw exception
-  }
-  if(option->defined(PREF_PEER_ID_PREFIX)) {
-    btContext->setPeerIdPrefix(option->get(PREF_PEER_ID_PREFIX));
+    bittorrent::loadFromMemory(torrentData, dctx, "default"); // may
+							      // throw
+							      // exception
   }
-  btContext->setFileFilter
-    (Util::parseIntRange(option->get(PREF_SELECT_FILE)));
+  dctx->setFileFilter(Util::parseIntRange(option->get(PREF_SELECT_FILE)));
   std::istringstream indexOutIn(option->get(PREF_INDEX_OUT));
   std::map<size_t, std::string> indexPathMap =
     Util::createIndexPathMap(indexOutIn);
   for(std::map<size_t, std::string>::const_iterator i = indexPathMap.begin();
       i != indexPathMap.end(); ++i) {
-    btContext->setFilePathWithIndex
-      ((*i).first, strconcat(btContext->getDir(), "/", (*i).second));
+    dctx->setFilePathWithIndex
+      ((*i).first, strconcat(dctx->getDir(), "/", (*i).second));
   }
-  rg->setDownloadContext(btContext);
-  btContext->setOwnerRequestGroup(rg.get());
+  rg->setDownloadContext(dctx);
+  dctx->setOwnerRequestGroup(rg.get());
   return rg;
 }
 
diff --git a/src/main.cc b/src/main.cc
index 1c4210bd..a3a13ffb 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -59,7 +59,6 @@
 #include "a2io.h"
 #include "a2time.h"
 #include "Platform.h"
-#include "DefaultBtContext.h"
 #include "FileEntry.h"
 #include "RequestGroup.h"
 #include "ConsoleStatCalc.h"
@@ -69,6 +68,10 @@
 #include "ProtocolDetector.h"
 #include "RecoverableException.h"
 #include "SocketCore.h"
+#include "DownloadContext.h"
+#ifdef ENABLE_BITTORRENT
+# include "bittorrent_helper.h"
+#endif // ENABLE_BITTORRENT
 #ifdef ENABLE_METALINK
 # include "MetalinkHelper.h"
 # include "MetalinkEntry.h"
@@ -108,9 +111,9 @@ std::ostream& getSummaryOut(const SharedHandle<Option>& op)
 #ifdef ENABLE_BITTORRENT
 static void showTorrentFile(const std::string& uri)
 {
-  SharedHandle<DefaultBtContext> btContext(new DefaultBtContext());
-  btContext->load(uri);
-  std::cout << btContext << std::endl;
+  SharedHandle<DownloadContext> dctx(new DownloadContext());
+  bittorrent::load(uri, dctx);
+  bittorrent::print(std::cout, dctx);
 }
 #endif // ENABLE_BITTORRENT
 
@@ -122,7 +125,7 @@ static void showMetalinkFile
   MetalinkHelper::parseAndQuery(metalinkEntries, uri, op.get());
   std::deque<SharedHandle<FileEntry> > fileEntries;
   MetalinkEntry::toFileEntry(fileEntries, metalinkEntries);
-  Util::toStream(std::cout, fileEntries);
+  Util::toStream(fileEntries.begin(), fileEntries.end(), std::cout);
   std::cout << std::endl;
 }
 #endif // ENABLE_METALINK
diff --git a/src/option_processing.cc b/src/option_processing.cc
index 8b27f197..240f2bac 100644
--- a/src/option_processing.cc
+++ b/src/option_processing.cc
@@ -54,6 +54,8 @@
 #include "StringFormat.h"
 #include "OptionHandlerException.h"
 #include "DownloadResult.h"
+#include "SimpleRandomizer.h"
+#include "bittorrent_helper.h"
 
 namespace aria2 {
 
@@ -202,6 +204,10 @@ void option_processing(Option& op, std::deque<std::string>& uris,
     }
   }
 #endif // HAVE_DAEMON
+#ifdef ENABLE_BITTORRENT
+  bittorrent::generateStaticPeerId(op.get(PREF_PEER_ID_PREFIX),
+				   SimpleRandomizer::getInstance());
+#endif // ENABLE_BITTORRENT
 }
 
 } // namespace aria2
author	Tatsuhiro Tsujikawa <tatsuhiro.t@gmail.com>	2009-06-28 10:37:15 +0000
committer	Tatsuhiro Tsujikawa <tatsuhiro.t@gmail.com>	2009-06-28 10:37:15 +0000
commit	5699b675268658ea958f7c2306e19849dff9bc41 (patch)
tree	c654c18eef6f4361cccf13854895b88967aa33ea /src
parent	90471d68050ebd05439435330e4d0dbb19c6fd1e (diff)