2008-05-13 Tatsuhiro Tsujikawa <tujikawa at rednoah dot com>

	Made string literal to static const std::string
	* src/DHTAbstractMessage.cc
	* src/DHTAnnouncePeerMessage.cc
	* src/DHTAnnouncePeerMessage.h
	* src/DHTAnnouncePeerReplyMessage.cc
	* src/DHTAnnouncePeerReplyMessage.h
	* src/DHTFindNodeMessage.cc
	* src/DHTFindNodeMessage.h
	* src/DHTFindNodeReplyMessage.cc
	* src/DHTFindNodeReplyMessage.h
	* src/DHTGetPeersMessage.cc
	* src/DHTGetPeersMessage.h
	* src/DHTGetPeersReplyMessage.cc
	* src/DHTGetPeersReplyMessage.h
	* src/DHTMessage.cc
	* src/DHTMessage.h
	* src/DHTMessageFactoryImpl.cc
	* src/DHTMessageReceiver.cc
	* src/DHTPingMessage.cc
	* src/DHTPingMessage.h
	* src/DHTPingReplyMessage.cc
	* src/DHTPingReplyMessage.h
	* src/DHTQueryMessage.cc
	* src/DHTQueryMessage.h
	* src/DHTResponseMessage.cc
	* src/DHTResponseMessage.h
	* src/DHTUnknownMessage.cc
	* src/DHTUnknownMessage.h

28 files changed, 207 insertions, 71 deletions

diff --git a/ChangeLog b/ChangeLog
index 055b38ba..c91a8f1a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,37 @@
 2008-05-13  Tatsuhiro Tsujikawa  <tujikawa at rednoah dot com>
 
 	Made string literal to static const std::string
+	* src/DHTAbstractMessage.cc
+	* src/DHTAnnouncePeerMessage.cc
+	* src/DHTAnnouncePeerMessage.h
+	* src/DHTAnnouncePeerReplyMessage.cc
+	* src/DHTAnnouncePeerReplyMessage.h
+	* src/DHTFindNodeMessage.cc
+	* src/DHTFindNodeMessage.h
+	* src/DHTFindNodeReplyMessage.cc
+	* src/DHTFindNodeReplyMessage.h
+	* src/DHTGetPeersMessage.cc
+	* src/DHTGetPeersMessage.h
+	* src/DHTGetPeersReplyMessage.cc
+	* src/DHTGetPeersReplyMessage.h
+	* src/DHTMessage.cc
+	* src/DHTMessage.h
+	* src/DHTMessageFactoryImpl.cc
+	* src/DHTMessageReceiver.cc
+	* src/DHTPingMessage.cc
+	* src/DHTPingMessage.h
+	* src/DHTPingReplyMessage.cc
+	* src/DHTPingReplyMessage.h
+	* src/DHTQueryMessage.cc
+	* src/DHTQueryMessage.h
+	* src/DHTResponseMessage.cc
+	* src/DHTResponseMessage.h
+	* src/DHTUnknownMessage.cc
+	* src/DHTUnknownMessage.h
+
+2008-05-13  Tatsuhiro Tsujikawa  <tujikawa at rednoah dot com>
+
+	Made string literal to static const std::string
 	* src/BtChokeMessage.cc (toString)
 	* src/BtHaveAllMessage.cc (toString)
 	* src/BtHaveNoneMessage.cc (toString)
diff --git a/src/DHTAbstractMessage.cc b/src/DHTAbstractMessage.cc
index 85d1fe72..fe6b46b9 100644
--- a/src/DHTAbstractMessage.cc
+++ b/src/DHTAbstractMessage.cc
@@ -55,8 +55,8 @@ DHTAbstractMessage::~DHTAbstractMessage() {}
 std::string DHTAbstractMessage::getBencodedMessage()
 {
   SharedHandle<Dictionary> msg(new Dictionary());
-  msg->put(std::string("t"), new Data(_transactionID));
-  msg->put(std::string("y"), new Data(getType()));
+  msg->put(DHTMessage::T, new Data(_transactionID));
+  msg->put(DHTMessage::Y, new Data(getType()));
   fillMessage(msg.get());
   
   BencodeVisitor v;
diff --git a/src/DHTAnnouncePeerMessage.cc b/src/DHTAnnouncePeerMessage.cc
index 802d361f..21422c43 100644
--- a/src/DHTAnnouncePeerMessage.cc
+++ b/src/DHTAnnouncePeerMessage.cc
@@ -50,6 +50,14 @@
 
 namespace aria2 {
 
+const std::string DHTAnnouncePeerMessage::ANNOUNCE_PEER("announce_peer");
+
+const std::string DHTAnnouncePeerMessage::INFO_HASH("info_hash");
+
+const std::string DHTAnnouncePeerMessage::PORT("port");
+
+const std::string DHTAnnouncePeerMessage::TOKEN("token");
+
 DHTAnnouncePeerMessage::DHTAnnouncePeerMessage(const SharedHandle<DHTNode>& localNode,
 					       const SharedHandle<DHTNode>& remoteNode,
 					       const unsigned char* infoHash,
@@ -78,19 +86,19 @@ void DHTAnnouncePeerMessage::doReceivedAction()
 Dictionary* DHTAnnouncePeerMessage::getArgument()
 {
   Dictionary* a = new Dictionary();
-  a->put("id", new Data(reinterpret_cast<const char*>(_localNode->getID()),
+  a->put(DHTMessage::ID, new Data(reinterpret_cast<const char*>(_localNode->getID()),
 			DHT_ID_LENGTH));
-  a->put("info_hash", new Data(reinterpret_cast<const char*>(_infoHash),
+  a->put(INFO_HASH, new Data(reinterpret_cast<const char*>(_infoHash),
 			       DHT_ID_LENGTH));
-  a->put("port", new Data(Util::uitos(_tcpPort), true));
-  a->put("token", new Data(_token));
+  a->put(PORT, new Data(Util::uitos(_tcpPort), true));
+  a->put(TOKEN, new Data(_token));
   
   return a;
 }
 
 std::string DHTAnnouncePeerMessage::getMessageType() const
 {
-  return "announce_peer";
+  return ANNOUNCE_PEER;
 }
 
 void DHTAnnouncePeerMessage::validate() const
diff --git a/src/DHTAnnouncePeerMessage.h b/src/DHTAnnouncePeerMessage.h
index 55380d53..ec00c6f1 100644
--- a/src/DHTAnnouncePeerMessage.h
+++ b/src/DHTAnnouncePeerMessage.h
@@ -93,6 +93,14 @@ public:
   void setPeerAnnounceStorage(const WeakHandle<DHTPeerAnnounceStorage>& storage);
 
   void setTokenTracker(const WeakHandle<DHTTokenTracker>& tokenTracker);
+
+  static const std::string ANNOUNCE_PEER;
+
+  static const std::string INFO_HASH;
+
+  static const std::string PORT;
+
+  static const std::string TOKEN;
 };
 
 } // namespace aria2
diff --git a/src/DHTAnnouncePeerReplyMessage.cc b/src/DHTAnnouncePeerReplyMessage.cc
index 5dc68ddb..edd99641 100644
--- a/src/DHTAnnouncePeerReplyMessage.cc
+++ b/src/DHTAnnouncePeerReplyMessage.cc
@@ -39,6 +39,8 @@
 
 namespace aria2 {
 
+const std::string DHTAnnouncePeerReplyMessage::ANNOUNCE_PEER("announce_peer");
+
 DHTAnnouncePeerReplyMessage::DHTAnnouncePeerReplyMessage(const SharedHandle<DHTNode>& localNode,
 							 const SharedHandle<DHTNode>& remoteNode,
 							 const std::string& transactionID):
@@ -51,13 +53,13 @@ void DHTAnnouncePeerReplyMessage::doReceivedAction() {}
 Dictionary* DHTAnnouncePeerReplyMessage::getResponse()
 {
   Dictionary* r = new Dictionary();
-  r->put("id", new Data(_localNode->getID(), DHT_ID_LENGTH));
+  r->put(DHTMessage::ID, new Data(_localNode->getID(), DHT_ID_LENGTH));
   return r;
 }
 
 std::string DHTAnnouncePeerReplyMessage::getMessageType() const
 {
-  return "announce_peer";
+  return ANNOUNCE_PEER;
 }
 
 void DHTAnnouncePeerReplyMessage::validate() const {}
diff --git a/src/DHTAnnouncePeerReplyMessage.h b/src/DHTAnnouncePeerReplyMessage.h
index 28309aba..98e50682 100644
--- a/src/DHTAnnouncePeerReplyMessage.h
+++ b/src/DHTAnnouncePeerReplyMessage.h
@@ -54,6 +54,8 @@ public:
   virtual std::string getMessageType() const;
 
   virtual void validate() const;
+
+  static const std::string ANNOUNCE_PEER;
 };
 
 } // namespace aria2
diff --git a/src/DHTFindNodeMessage.cc b/src/DHTFindNodeMessage.cc
index 951c14e3..f5b0ab2c 100644
--- a/src/DHTFindNodeMessage.cc
+++ b/src/DHTFindNodeMessage.cc
@@ -45,6 +45,10 @@
 
 namespace aria2 {
 
+const std::string DHTFindNodeMessage::FIND_NODE("find_node");
+
+const std::string DHTFindNodeMessage::TARGET_NODE("target");
+
 DHTFindNodeMessage::DHTFindNodeMessage(const SharedHandle<DHTNode>& localNode,
 				       const SharedHandle<DHTNode>& remoteNode,
 				       const unsigned char* targetNodeID,
@@ -68,16 +72,16 @@ void DHTFindNodeMessage::doReceivedAction()
 Dictionary* DHTFindNodeMessage::getArgument()
 {
   Dictionary* a = new Dictionary();
-  a->put("id", new Data(reinterpret_cast<const char*>(_localNode->getID()),
+  a->put(DHTMessage::ID, new Data(reinterpret_cast<const char*>(_localNode->getID()),
 			DHT_ID_LENGTH));
-  a->put("target", new Data(reinterpret_cast<const char*>(_targetNodeID),
+  a->put(TARGET_NODE, new Data(reinterpret_cast<const char*>(_targetNodeID),
 			    DHT_ID_LENGTH));
   return a;
 }
 
 std::string DHTFindNodeMessage::getMessageType() const
 {
-  return "find_node";
+  return FIND_NODE;
 }
 
 void DHTFindNodeMessage::validate() const {}
diff --git a/src/DHTFindNodeMessage.h b/src/DHTFindNodeMessage.h
index 1fc9d97c..95486ac8 100644
--- a/src/DHTFindNodeMessage.h
+++ b/src/DHTFindNodeMessage.h
@@ -65,6 +65,11 @@ public:
   {
     return _targetNodeID;
   }
+
+  static const std::string FIND_NODE;
+
+  // We want "TARGET", but it is defined by macro.
+  static const std::string TARGET_NODE;
 };
 
 } // namespace aria2
diff --git a/src/DHTFindNodeReplyMessage.cc b/src/DHTFindNodeReplyMessage.cc
index 67570618..47f06db1 100644
--- a/src/DHTFindNodeReplyMessage.cc
+++ b/src/DHTFindNodeReplyMessage.cc
@@ -47,6 +47,10 @@
 
 namespace aria2 {
 
+const std::string DHTFindNodeReplyMessage::FIND_NODE("find_node");
+
+const std::string DHTFindNodeReplyMessage::NODES("nodes");
+
 DHTFindNodeReplyMessage::DHTFindNodeReplyMessage(const SharedHandle<DHTNode>& localNode,
 						 const SharedHandle<DHTNode>& remoteNode,
 						 const std::string& transactionID):
@@ -66,7 +70,7 @@ void DHTFindNodeReplyMessage::doReceivedAction()
 Dictionary* DHTFindNodeReplyMessage::getResponse()
 {
   Dictionary* a = new Dictionary();
-  a->put("id", new Data(_localNode->getID(), DHT_ID_LENGTH));
+  a->put(DHTMessage::ID, new Data(_localNode->getID(), DHT_ID_LENGTH));
   size_t offset = 0;
   unsigned char buffer[DHTBucket::K*26];
   // TODO if _closestKNodes.size() > DHTBucket::K ??
@@ -77,13 +81,13 @@ Dictionary* DHTFindNodeReplyMessage::getResponse()
       offset += 26;
     }
   }
-  a->put("nodes", new Data(buffer, offset));
+  a->put(NODES, new Data(buffer, offset));
   return a;
 }
 
 std::string DHTFindNodeReplyMessage::getMessageType() const
 {
-  return "find_node";
+  return FIND_NODE;
 }
 
 void DHTFindNodeReplyMessage::validate() const {}
diff --git a/src/DHTFindNodeReplyMessage.h b/src/DHTFindNodeReplyMessage.h
index 3d301579..c3ef632c 100644
--- a/src/DHTFindNodeReplyMessage.h
+++ b/src/DHTFindNodeReplyMessage.h
@@ -63,6 +63,10 @@ public:
   const std::deque<SharedHandle<DHTNode> >& getClosestKNodes() const;
 
   void setClosestKNodes(const std::deque<SharedHandle<DHTNode> >& closestKNodes);
+
+  static const std::string FIND_NODE;
+  
+  static const std::string NODES;
 };
 
 } // namespace aria2
diff --git a/src/DHTGetPeersMessage.cc b/src/DHTGetPeersMessage.cc
index f0333580..5a4a6291 100644
--- a/src/DHTGetPeersMessage.cc
+++ b/src/DHTGetPeersMessage.cc
@@ -49,6 +49,10 @@
 
 namespace aria2 {
 
+const std::string DHTGetPeersMessage::GET_PEERS("get_peers");
+
+const std::string DHTGetPeersMessage::INFO_HASH("info_hash");
+
 DHTGetPeersMessage::DHTGetPeersMessage(const SharedHandle<DHTNode>& localNode,
 				       const SharedHandle<DHTNode>& remoteNode,
 				       const unsigned char* infoHash,
@@ -86,14 +90,14 @@ void DHTGetPeersMessage::doReceivedAction()
 Dictionary* DHTGetPeersMessage::getArgument()
 {
   Dictionary* a = new Dictionary();
-  a->put("id", new Data(_localNode->getID(), DHT_ID_LENGTH));
-  a->put("info_hash", new Data(_infoHash, DHT_ID_LENGTH));
+  a->put(DHTMessage::ID, new Data(_localNode->getID(), DHT_ID_LENGTH));
+  a->put(INFO_HASH, new Data(_infoHash, DHT_ID_LENGTH));
   return a;
 }
 
 std::string DHTGetPeersMessage::getMessageType() const
 {
-  return "get_peers";
+  return GET_PEERS;
 }
 
 void DHTGetPeersMessage::validate() const {}
diff --git a/src/DHTGetPeersMessage.h b/src/DHTGetPeersMessage.h
index 42b4d6ce..20ed3474 100644
--- a/src/DHTGetPeersMessage.h
+++ b/src/DHTGetPeersMessage.h
@@ -78,6 +78,11 @@ public:
 
 
   void setTokenTracker(const WeakHandle<DHTTokenTracker>& tokenTracker);
+
+  static const std::string GET_PEERS;
+
+  static const std::string INFO_HASH;
+
 };
 
 } // namespace aria2
diff --git a/src/DHTGetPeersReplyMessage.cc b/src/DHTGetPeersReplyMessage.cc
index 725a9670..6c0fb423 100644
--- a/src/DHTGetPeersReplyMessage.cc
+++ b/src/DHTGetPeersReplyMessage.cc
@@ -50,6 +50,14 @@
 
 namespace aria2 {
 
+const std::string DHTGetPeersReplyMessage::GET_PEERS("get_peers");
+
+const std::string DHTGetPeersReplyMessage::TOKEN("token");
+
+const std::string DHTGetPeersReplyMessage::VALUES("values");
+
+const std::string DHTGetPeersReplyMessage::NODES("nodes");
+
 DHTGetPeersReplyMessage::DHTGetPeersReplyMessage(const SharedHandle<DHTNode>& localNode,
 						 const SharedHandle<DHTNode>& remoteNode,
 						 const std::string& token,
@@ -67,11 +75,11 @@ void DHTGetPeersReplyMessage::doReceivedAction()
 Dictionary* DHTGetPeersReplyMessage::getResponse()
 {
   Dictionary* r = new Dictionary();
-  r->put("id", new Data(_localNode->getID(), DHT_ID_LENGTH));
-  r->put("token", new Data(_token));
+  r->put(DHTMessage::ID, new Data(_localNode->getID(), DHT_ID_LENGTH));
+  r->put(TOKEN, new Data(_token));
   if(_values.size()) {
     List* valuesList = new List();
-    r->put("values", valuesList);
+    r->put(VALUES, valuesList);
     for(std::deque<SharedHandle<Peer> >::const_iterator i = _values.begin(); i != _values.end(); ++i) {
       const SharedHandle<Peer>& peer = *i;
       unsigned char buffer[6];
@@ -89,14 +97,14 @@ Dictionary* DHTGetPeersReplyMessage::getResponse()
 	offset += 26;
       }
     }
-    r->put("nodes", new Data(buffer, offset));
+    r->put(NODES, new Data(buffer, offset));
   }
   return r;
 }
 
 std::string DHTGetPeersReplyMessage::getMessageType() const
 {
-  return "get_peers";
+  return GET_PEERS;
 }
 
 void DHTGetPeersReplyMessage::validate() const {}
diff --git a/src/DHTGetPeersReplyMessage.h b/src/DHTGetPeersReplyMessage.h
index daedc27a..5b526546 100644
--- a/src/DHTGetPeersReplyMessage.h
+++ b/src/DHTGetPeersReplyMessage.h
@@ -80,6 +80,14 @@ public:
   {
     return _token;
   }
+
+  static const std::string GET_PEERS;
+
+  static const std::string TOKEN;
+
+  static const std::string VALUES;
+
+  static const std::string NODES;
 };
 
 } // namespace aria2
diff --git a/src/DHTMessage.cc b/src/DHTMessage.cc
index 5b1d07e4..0ecc2fe2 100644
--- a/src/DHTMessage.cc
+++ b/src/DHTMessage.cc
@@ -38,6 +38,12 @@
 
 namespace aria2 {
 
+const std::string DHTMessage::Y("y");
+
+const std::string DHTMessage::T("t");
+
+const std::string DHTMessage::ID("id");
+
 DHTMessage::DHTMessage(const SharedHandle<DHTNode>& localNode,
 		       const SharedHandle<DHTNode>& remoteNode,
 		       const std::string& transactionID):
@@ -67,5 +73,4 @@ SharedHandle<DHTNode> DHTMessage::getRemoteNode() const
   return _remoteNode;
 }
 
-
 } // namespace aria2
diff --git a/src/DHTMessage.h b/src/DHTMessage.h
index 53bde055..bc018fdd 100644
--- a/src/DHTMessage.h
+++ b/src/DHTMessage.h
@@ -80,6 +80,12 @@ public:
   virtual std::string getMessageType() const = 0;
 
   virtual std::string toString() const = 0;
+
+  static const std::string Y;
+
+  static const std::string T;
+
+  static const std::string ID;
 };
 
 } // namespace aria2
diff --git a/src/DHTMessageFactoryImpl.cc b/src/DHTMessageFactoryImpl.cc
index cbe083e9..e2621708 100644
--- a/src/DHTMessageFactoryImpl.cc
+++ b/src/DHTMessageFactoryImpl.cc
@@ -160,36 +160,36 @@ SharedHandle<DHTMessage> DHTMessageFactoryImpl::createQueryMessage(const Diction
 							   const std::string& ipaddr,
 							   uint16_t port)
 {
-  const Data* q = getData(d, "q");
-  const Data* t = getData(d, "t");
-  const Data* y = getData(d, "y");
-  const Dictionary* a = getDictionary(d, "a");
-  if(y->toString() != "q") {
+  const Data* q = getData(d, DHTQueryMessage::Q);
+  const Data* t = getData(d, DHTMessage::T);
+  const Data* y = getData(d, DHTMessage::Y);
+  const Dictionary* a = getDictionary(d, DHTQueryMessage::A);
+  if(y->toString() != DHTQueryMessage::Q) {
     throw DlAbortEx("Malformed DHT message. y != q");
   }
-  const Data* id = getData(getDictionary(d, "a"), "id");
+  const Data* id = getData(getDictionary(d, DHTQueryMessage::A), DHTMessage::ID);
   validateID(id);
   SharedHandle<DHTNode> remoteNode = getRemoteNode(id->getData(), ipaddr, port);
   std::string messageType = q->toString();
   std::string transactionID = t->toString();
-  if(messageType == "ping") {
+  if(messageType == DHTPingMessage::PING) {
     return createPingMessage(remoteNode, transactionID);
-  } else if(messageType == "find_node") {
-    const Data* targetNodeID = getData(a, "target");
+  } else if(messageType == DHTFindNodeMessage::FIND_NODE) {
+    const Data* targetNodeID = getData(a, DHTFindNodeMessage::TARGET_NODE);
     validateID(targetNodeID);
     return createFindNodeMessage(remoteNode, targetNodeID->getData(),
 				 transactionID);
-  } else if(messageType == "get_peers") {
-    const Data* infoHash = getData(a, "info_hash");
+  } else if(messageType == DHTGetPeersMessage::GET_PEERS) {
+    const Data* infoHash = getData(a, DHTGetPeersMessage::INFO_HASH);
     validateID(infoHash);
     return createGetPeersMessage(remoteNode,
 				 infoHash->getData(), transactionID);
-  } else if(messageType == "announce_peer") {
-    const Data* infoHash = getData(a, "info_hash");
+  } else if(messageType == DHTAnnouncePeerMessage::ANNOUNCE_PEER) {
+    const Data* infoHash = getData(a, DHTAnnouncePeerMessage::INFO_HASH);
     validateID(infoHash);
-    const Data* port = getData(a, "port");
+    const Data* port = getData(a, DHTAnnouncePeerMessage::PORT);
     validatePort(port);
-    const Data* token = getData(a, "token");
+    const Data* token = getData(a, DHTAnnouncePeerMessage::TOKEN);
     return createAnnouncePeerMessage(remoteNode, infoHash->getData(),
 				     static_cast<uint16_t>(port->toInt()),
 				     token->toString(), transactionID);
@@ -204,11 +204,11 @@ DHTMessageFactoryImpl::createResponseMessage(const std::string& messageType,
 					     const Dictionary* d,
 					     const SharedHandle<DHTNode>& remoteNode)
 {
-  const Data* t = getData(d, "t");
-  const Data* y = getData(d, "y");
-  if(y->toString() == "e") {
+  const Data* t = getData(d, DHTMessage::T);
+  const Data* y = getData(d, DHTMessage::Y);
+  if(y->toString() == DHTUnknownMessage::E) {
     // for now, just report error message arrived and throw exception.
-    const List* e = getList(d, "e");
+    const List* e = getList(d, DHTUnknownMessage::E);
     if(e->getList().size() == 2) {
       _logger->info("Received Error DHT message. code=%s, msg=%s",
 		    Util::urlencode(getData(e, 0)->toString()).c_str(),
@@ -217,34 +217,35 @@ DHTMessageFactoryImpl::createResponseMessage(const std::string& messageType,
       _logger->debug("e doesn't have 2 elements.");
     }
     throw DlAbortEx("Received Error DHT message.");
-  } else if(y->toString() != "r") {
+  } else if(y->toString() != DHTResponseMessage::R) {
     throw DlAbortEx
       (StringFormat("Malformed DHT message. y != r: y=%s",
 		    Util::urlencode(y->toString()).c_str()).str());
   }
-  const Dictionary* r = getDictionary(d, "r");
-  const Data* id = getData(r, "id");
+  const Dictionary* r = getDictionary(d, DHTResponseMessage::R);
+  const Data* id = getData(r, DHTMessage::ID);
   validateID(id);
   validateIDMatch(remoteNode->getID(), id->getData());
   std::string transactionID = t->toString();
-  if(messageType == "ping") {
+  if(messageType == DHTPingReplyMessage::PING) {
     return createPingReplyMessage(remoteNode,
 				  id->getData(), transactionID);
-  } else if(messageType == "find_node") {
+  } else if(messageType == DHTFindNodeReplyMessage::FIND_NODE) {
     return createFindNodeReplyMessage(remoteNode, d, transactionID);
-  } else if(messageType == "get_peers") {
-    const List* values = dynamic_cast<const List*>(r->get("values"));
+  } else if(messageType == DHTGetPeersReplyMessage::GET_PEERS) {
+    const List* values =
+      dynamic_cast<const List*>(r->get(DHTGetPeersReplyMessage::VALUES));
     if(values) {
       return createGetPeersReplyMessageWithValues(remoteNode, d, transactionID);
     } else {
-      const Data* nodes = dynamic_cast<const Data*>(r->get("nodes"));
+      const Data* nodes = dynamic_cast<const Data*>(r->get(DHTGetPeersReplyMessage::NODES));
       if(nodes) {
 	return createGetPeersReplyMessageWithNodes(remoteNode, d, transactionID);
       } else {
 	throw DlAbortEx("Malformed DHT message: missing nodes/values");
       }
     }
-  } else if(messageType == "announce_peer") {
+  } else if(messageType == DHTAnnouncePeerReplyMessage::ANNOUNCE_PEER) {
     return createAnnouncePeerReplyMessage(remoteNode, transactionID);
   } else {
     throw DlAbortEx
@@ -325,7 +326,7 @@ DHTMessageFactoryImpl::createFindNodeReplyMessage(const SharedHandle<DHTNode>& r
 						  const Dictionary* d,
 						  const std::string& transactionID)
 {
-  const Data* nodesData = getData(getDictionary(d, "r"), "nodes");
+  const Data* nodesData = getData(getDictionary(d, DHTResponseMessage::R), DHTFindNodeReplyMessage::NODES);
   std::deque<SharedHandle<DHTNode> > nodes = extractNodes(nodesData->getData(), nodesData->getLen());
   return createFindNodeReplyMessage(remoteNode, nodes, transactionID);
 }
@@ -350,10 +351,10 @@ DHTMessageFactoryImpl::createGetPeersReplyMessageWithNodes(const SharedHandle<DH
 							   const Dictionary* d,
 							   const std::string& transactionID)
 {
-  const Dictionary* r = getDictionary(d, "r");
-  const Data* nodesData = getData(r, "nodes");
+  const Dictionary* r = getDictionary(d, DHTResponseMessage::R);
+  const Data* nodesData = getData(r, DHTGetPeersReplyMessage::NODES);
   std::deque<SharedHandle<DHTNode> > nodes = extractNodes(nodesData->getData(), nodesData->getLen());
-  const Data* token = getData(r, "token");
+  const Data* token = getData(r, DHTGetPeersReplyMessage::TOKEN);
   return createGetPeersReplyMessage(remoteNode, nodes, token->toString(),
 				    transactionID);
 }
@@ -376,8 +377,8 @@ DHTMessageFactoryImpl::createGetPeersReplyMessageWithValues(const SharedHandle<D
 							    const Dictionary* d,
 							    const std::string& transactionID)
 {
-  const Dictionary* r = getDictionary(d, "r");
-  const List* valuesList = getList(r, "values");
+  const Dictionary* r = getDictionary(d, DHTResponseMessage::R);
+  const List* valuesList = getList(r, DHTGetPeersReplyMessage::VALUES);
   std::deque<SharedHandle<Peer> > peers;
   for(std::deque<MetaEntry*>::const_iterator i = valuesList->getList().begin(); i != valuesList->getList().end(); ++i) {
     const Data* data = dynamic_cast<const Data*>(*i);
@@ -387,7 +388,7 @@ DHTMessageFactoryImpl::createGetPeersReplyMessageWithValues(const SharedHandle<D
       peers.push_back(peer);
     }
   }
-  const Data* token = getData(r, "token");
+  const Data* token = getData(r, DHTGetPeersReplyMessage::TOKEN);
   return createGetPeersReplyMessage(remoteNode, peers, token->toString(),
 				    transactionID);
 }
diff --git a/src/DHTMessageReceiver.cc b/src/DHTMessageReceiver.cc
index ff3a159d..8fcfaefa 100644
--- a/src/DHTMessageReceiver.cc
+++ b/src/DHTMessageReceiver.cc
@@ -36,6 +36,8 @@
 #include "DHTMessageTracker.h"
 #include "DHTConnection.h"
 #include "DHTMessage.h"
+#include "DHTResponseMessage.h"
+#include "DHTUnknownMessage.h"
 #include "DHTMessageFactory.h"
 #include "DHTRoutingTable.h"
 #include "DHTNode.h"
@@ -74,9 +76,10 @@ SharedHandle<DHTMessage> DHTMessageReceiver::receiveMessage()
     MetaEntryHandle msgroot(MetaFileUtil::bdecoding(data, length));
     const Dictionary* d = dynamic_cast<const Dictionary*>(msgroot.get());
     if(d) {
-      const Data* y = dynamic_cast<const Data*>(d->get("y"));
+      const Data* y = dynamic_cast<const Data*>(d->get(DHTMessage::Y));
       if(y) {
-	if(y->toString() == "r" || y->toString() == "e") {
+	if(y->toString() == DHTResponseMessage::R ||
+	   y->toString() == DHTUnknownMessage::E) {
 	  isReply = true;
 	}
       } else {
diff --git a/src/DHTPingMessage.cc b/src/DHTPingMessage.cc
index 45fa1ee5..9e396625 100644
--- a/src/DHTPingMessage.cc
+++ b/src/DHTPingMessage.cc
@@ -43,6 +43,8 @@
 
 namespace aria2 {
 
+const std::string DHTPingMessage::PING("ping");
+
 DHTPingMessage::DHTPingMessage(const SharedHandle<DHTNode>& localNode,
 			       const SharedHandle<DHTNode>& remoteNode,
 			       const std::string& transactionID):
@@ -60,14 +62,14 @@ void DHTPingMessage::doReceivedAction()
 Dictionary* DHTPingMessage::getArgument()
 {
   Dictionary* a = new Dictionary();
-  a->put("id", new Data(reinterpret_cast<const char*>(_localNode->getID()),
+  a->put(DHTMessage::ID, new Data(reinterpret_cast<const char*>(_localNode->getID()),
 			DHT_ID_LENGTH));
   return a;
 }
 
 std::string DHTPingMessage::getMessageType() const
 {
-  return "ping";
+  return PING;
 }
 
 void DHTPingMessage::validate() const {}
diff --git a/src/DHTPingMessage.h b/src/DHTPingMessage.h
index f1be9fe3..8b458cbc 100644
--- a/src/DHTPingMessage.h
+++ b/src/DHTPingMessage.h
@@ -55,6 +55,8 @@ public:
   virtual std::string getMessageType() const;
 
   virtual void validate() const;
+
+  static const std::string PING;
 };
 
 } // namespace aria2
diff --git a/src/DHTPingReplyMessage.cc b/src/DHTPingReplyMessage.cc
index 068483fb..b4c75984 100644
--- a/src/DHTPingReplyMessage.cc
+++ b/src/DHTPingReplyMessage.cc
@@ -40,6 +40,8 @@
 
 namespace aria2 {
 
+const std::string DHTPingReplyMessage::PING("ping");
+
 DHTPingReplyMessage::DHTPingReplyMessage(const SharedHandle<DHTNode>& localNode,
 					 const SharedHandle<DHTNode>& remoteNode,
 					 const unsigned char* id,
@@ -56,13 +58,13 @@ void DHTPingReplyMessage::doReceivedAction() {}
 Dictionary* DHTPingReplyMessage::getResponse()
 {
   Dictionary* r = new Dictionary();
-  r->put("id", new Data(_id, DHT_ID_LENGTH));
+  r->put(DHTMessage::ID, new Data(_id, DHT_ID_LENGTH));
   return r;
 }
 
 std::string DHTPingReplyMessage::getMessageType() const
 {
-  return "ping";
+  return PING;
 }
 
 void DHTPingReplyMessage::validate() const {}
diff --git a/src/DHTPingReplyMessage.h b/src/DHTPingReplyMessage.h
index b95eaa01..5c4130cf 100644
--- a/src/DHTPingReplyMessage.h
+++ b/src/DHTPingReplyMessage.h
@@ -63,6 +63,8 @@ public:
   {
     return _id;
   }
+
+  static const std::string PING;
 };
 
 } // namespace aria2
diff --git a/src/DHTQueryMessage.cc b/src/DHTQueryMessage.cc
index 1ded98ab..895a2dc5 100644
--- a/src/DHTQueryMessage.cc
+++ b/src/DHTQueryMessage.cc
@@ -40,6 +40,10 @@
 
 namespace aria2 {
 
+const std::string DHTQueryMessage::Q("q");
+
+const std::string DHTQueryMessage::A("a");
+
 DHTQueryMessage::DHTQueryMessage(const SharedHandle<DHTNode>& localNode,
 				 const SharedHandle<DHTNode>& remoteNode,
 				 const std::string& transactionID):
@@ -49,13 +53,13 @@ DHTQueryMessage::~DHTQueryMessage() {}
 
 std::string DHTQueryMessage::getType() const
 {
-  return "q";
+  return Q;
 }
 
 void DHTQueryMessage::fillMessage(Dictionary* message)
 {
-  message->put("q", new Data(getMessageType()));
-  message->put("a", getArgument());
+  message->put(Q, new Data(getMessageType()));
+  message->put(A, getArgument());
 }
 
 bool DHTQueryMessage::isReply() const
diff --git a/src/DHTQueryMessage.h b/src/DHTQueryMessage.h
index 76505239..dc9cb22f 100644
--- a/src/DHTQueryMessage.h
+++ b/src/DHTQueryMessage.h
@@ -59,6 +59,10 @@ public:
   virtual bool isReply() const;
 
   virtual std::string toString() const;
+
+  static const std::string Q;
+
+  static const std::string A;
 };
 
 } // namespace aria2
diff --git a/src/DHTResponseMessage.cc b/src/DHTResponseMessage.cc
index 5a66daae..b9cd374b 100644
--- a/src/DHTResponseMessage.cc
+++ b/src/DHTResponseMessage.cc
@@ -40,6 +40,8 @@
 
 namespace aria2 {
 
+const std::string DHTResponseMessage::R("r");
+
 DHTResponseMessage::DHTResponseMessage(const SharedHandle<DHTNode>& localNode,
 				       const SharedHandle<DHTNode>& remoteNode,
 				       const std::string& transactionID):
@@ -49,12 +51,12 @@ DHTResponseMessage::~DHTResponseMessage() {}
 
 std::string DHTResponseMessage::getType() const
 {
-  return "r";
+  return R;
 }
 
 void DHTResponseMessage::fillMessage(Dictionary* message)
 {
-  message->put("r", getResponse());
+  message->put(R, getResponse());
 }
 
 bool DHTResponseMessage::isReply() const
diff --git a/src/DHTResponseMessage.h b/src/DHTResponseMessage.h
index 2c4fb03a..8a2ecc79 100644
--- a/src/DHTResponseMessage.h
+++ b/src/DHTResponseMessage.h
@@ -59,6 +59,8 @@ public:
   virtual bool isReply() const;
 
   virtual std::string toString() const;
+
+  static const std::string R;
 };
 
 } // namespace aria2
diff --git a/src/DHTUnknownMessage.cc b/src/DHTUnknownMessage.cc
index d188ab08..ab2b0fa2 100644
--- a/src/DHTUnknownMessage.cc
+++ b/src/DHTUnknownMessage.cc
@@ -39,6 +39,10 @@
 
 namespace aria2 {
 
+const std::string DHTUnknownMessage::E("e");
+
+const std::string DHTUnknownMessage::UNKNOWN("unknown");
+
 DHTUnknownMessage::DHTUnknownMessage(const SharedHandle<DHTNode>& localNode,
 				     const unsigned char* data, size_t length,
 				     const std::string& ipaddr, uint16_t port):
@@ -73,7 +77,7 @@ void DHTUnknownMessage::validate() const {}
   
 std::string DHTUnknownMessage::getMessageType() const
 {
-  return "unknown";
+  return UNKNOWN;
 }
 
 std::string DHTUnknownMessage::toString() const
diff --git a/src/DHTUnknownMessage.h b/src/DHTUnknownMessage.h
index 76dce6d2..47c37584 100644
--- a/src/DHTUnknownMessage.h
+++ b/src/DHTUnknownMessage.h
@@ -69,6 +69,10 @@ public:
 
   // show some sample bytes
   virtual std::string toString() const;
+
+  static const std::string E;
+
+  static const std::string UNKNOWN;
 };
 
 } // namespace aria2