Make QUIC version negotiation stateless. The QUIC dispatcher now detects version mismatch before cr…

net/quic/quic_framer.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/quic_framer.h"
 
 #include <stdint.h>
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
@@ skipping 957 matching lines @@
   if (public_header->version_flag && perspective_ == Perspective::IS_SERVER) {
     QuicTag version_tag;
     if (!reader->ReadUInt32(&version_tag)) {
       set_detailed_error("Unable to read protocol version.");
       return false;
     }
 
     // If the version from the new packet is the same as the version of this
     // framer, then the public flags should be set to something we understand.
     // If not, this raises an error.
+    last_version_tag_ = version_tag;
     QuicVersion version = QuicTagToQuicVersion(version_tag);
     if (version == quic_version_ && public_flags > PACKET_PUBLIC_FLAGS_MAX) {
       set_detailed_error("Illegal public flags value.");
       return false;
     }
     public_header->versions.push_back(version);
   }
   return true;
 }
 
@@ skipping 1319 matching lines @@
 
 bool QuicFramer::RaiseError(QuicErrorCode error) {
   DVLOG(1) << "Error: " << QuicUtils::ErrorToString(error)
            << " detail: " << detailed_error_;
   set_error(error);
   visitor_->OnError(this);
   return false;
 }
 
 }  // namespace net