Implemented Metalink/HTTP in HTTP download.

Link header fields from first Metalink server is utilized as described
in rfc6249. We only set digest from Digest header field to
DownloadContext only when PieceStorage is not initialized(in other
words, before file size is known). After PieceStorage is initialized,
Digest header field is used to check the value is the same in digest
in DownloadContext.  Current implementation only handles
rel=duplicate.

1 files changed, 70 insertions, 0 deletions

diff --git a/src/HttpResponseCommand.cc b/src/HttpResponseCommand.cc
index 88c19a21..c02e324b 100644
--- a/src/HttpResponseCommand.cc
+++ b/src/HttpResponseCommand.cc
@@ -72,6 +72,10 @@
 #include "ChunkedDecodingStreamFilter.h"
 #include "uri.h"
 #include "SocketRecvBuffer.h"
+#include "MetalinkHttpEntry.h"
+#ifdef ENABLE_MESSAGE_DIGEST
+#include "Checksum.h"
+#endif // ENABLE_MESSAGE_DIGEST
 #ifdef HAVE_ZLIB
 # include "GZipDecodingStreamFilter.h"
 #endif // HAVE_ZLIB
@@ -189,6 +193,42 @@ bool HttpResponseCommand::executeInternal()
     getFileEntry()->poolRequest(getRequest());
     return true;
   }
+  if(!getPieceStorage()) {
+    // Metalink/HTTP
+    if(!getDownloadContext()->getMetalinkServerContacted()) {
+      if(httpHeader->defined(HttpHeader::LINK)) {
+        getDownloadContext()->setMetalinkServerContacted(true);
+        std::vector<MetalinkHttpEntry> entries;
+        httpResponse->getMetalinKHttpEntries(entries, getOption());
+        for(std::vector<MetalinkHttpEntry>::iterator i = entries.begin(),
+              eoi = entries.end(); i != eoi; ++i) {
+          getFileEntry()->addUri((*i).uri);
+          A2_LOG_DEBUG(fmt("Adding URI=%s", (*i).uri.c_str()));
+        }
+      }
+    }
+#ifdef ENABLE_MESSAGE_DIGEST
+    if(httpHeader->defined(HttpHeader::DIGEST)) {
+      std::vector<Checksum> checksums;
+      httpResponse->getDigest(checksums);
+      for(std::vector<Checksum>::iterator i = checksums.begin(),
+            eoi = checksums.end(); i != eoi; ++i) {
+        if(getDownloadContext()->getChecksumHashAlgo().empty()) {
+          A2_LOG_DEBUG(fmt("Setting digest: type=%s, digest=%s",
+                           (*i).getAlgo().c_str(),
+                           (*i).getMessageDigest().c_str()));
+          getDownloadContext()->setChecksumHashAlgo((*i).getAlgo());
+          getDownloadContext()->setChecksum((*i).getMessageDigest());
+          break;
+        } else {
+          if(checkChecksum(getDownloadContext(), *i)) {
+            break;
+          }
+        }
+      }
+    }
+#endif // ENABLE_MESSAGE_DIGEST
+  }
   if(statusCode >= 300) {
     if(statusCode == 404) {
       getRequestGroup()->increaseAndValidateFileNotFoundCount();
@@ -241,6 +281,19 @@ bool HttpResponseCommand::executeInternal()
       return handleDefaultEncoding(httpResponse);
     }
   } else {
+#ifdef ENABLE_MESSAGE_DIGEST
+    if(!getDownloadContext()->getChecksumHashAlgo().empty() &&
+       httpHeader->defined(HttpHeader::DIGEST)) {
+      std::vector<Checksum> checksums;
+      httpResponse->getDigest(checksums);
+      for(std::vector<Checksum>::iterator i = checksums.begin(),
+            eoi = checksums.end(); i != eoi; ++i) {
+        if(checkChecksum(getDownloadContext(), *i)) {
+          break;
+        }
+      }
+    }
+#endif // ENABLE_MESSAGE_DIGEST
     // validate totalsize
     getRequestGroup()->validateTotalLength(getFileEntry()->getLength(),
                                        httpResponse->getEntityLength());
@@ -501,4 +554,21 @@ void HttpResponseCommand::onDryRunFileFound()
   poolConnection();
 }
 
+#ifdef ENABLE_MESSAGE_DIGEST
+bool HttpResponseCommand::checkChecksum
+(const SharedHandle<DownloadContext>& dctx,
+ const Checksum& checksum)
+{
+  if(dctx->getChecksumHashAlgo() == checksum.getAlgo()) {
+    if(dctx->getChecksum() == checksum.getMessageDigest()) {
+      A2_LOG_INFO("Valid hash found in Digest header field.");
+      return true;
+    } else {
+      throw DL_ABORT_EX("Invalid hash found in Digest header field.");
+    }
+  }
+  return false;
+}
+#endif // ENABLE_MESSAGE_DIGEST
+
 } // namespace aria2