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

net/quic/quic_framer.h

 // 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.
 
 #ifndef NET_QUIC_QUIC_FRAMER_H_
 #define NET_QUIC_QUIC_FRAMER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 351 matching lines @@
   void set_validate_flags(bool value) { validate_flags_ = value; }
 
   Perspective perspective() const { return perspective_; }
 
   static QuicPacketEntropyHash GetPacketEntropyHash(
       const QuicPacketHeader& header);
 
   // Called when a PATH_CLOSED frame has been sent/received on |path_id|.
   void OnPathClosed(QuicPathId path_id);
 
+  QuicTag last_version_tag() { return last_version_tag_; }
+
  private:
   friend class test::QuicFramerPeer;
 
   typedef std::map<QuicPacketNumber, uint8_t> NackRangeMap;
 
   struct AckFrameInfo {
     AckFrameInfo();
     AckFrameInfo(const AckFrameInfo& other);
     ~AckFrameInfo();
 
@@ skipping 147 matching lines @@
   std::unordered_set<QuicPathId> closed_paths_;
   // Map mapping path id to packet number of last successfully decrypted/revived
   // received packet.
   std::unordered_map<QuicPathId, QuicPacketNumber> last_packet_numbers_;
   // Updated by ProcessPacketHeader when it succeeds.
   QuicPacketNumber last_packet_number_;
   // The path on which last successfully decrypted/revived packet was received.
   QuicPathId last_path_id_;
   // Updated by WritePacketHeader.
   QuicConnectionId last_serialized_connection_id_;
+  // The last QUIC version tag received.
+  QuicTag last_version_tag_;
   // Version of the protocol being used.
   QuicVersion quic_version_;
   // This vector contains QUIC versions which we currently support.
   // This should be ordered such that the highest supported version is the first
   // element, with subsequent elements in descending order (versions can be
   // skipped as necessary).
   QuicVersionVector supported_versions_;
   // Primary decrypter used to decrypt packets during parsing.
   scoped_ptr<QuicDecrypter> decrypter_;
   // Alternative decrypter that can also be used to decrypt packets.
@@ skipping 19 matching lines @@
   // The time delta computed for the last timestamp frame. This is relative to
   // the creation_time.
   QuicTime::Delta last_timestamp_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicFramer);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_FRAMER_H_