Allows QUIC connections to remain established even though the peer's

net/quic/quic_connection.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.
 //
 // The entity that handles framing writes for a Quic client or server.
 // Each QuicSession will have a connection associated with it.
 //
 // On the server side, the Dispatcher handles the raw reads, and hands off
 // packets via ProcessUdpPacket for framing and processing.
 //
@@ skipping 593 matching lines @@
   // Get the FEC group associate with the last processed packet or NULL, if the
   // group has already been deleted.
   QuicFecGroup* GetFecGroup();
 
   // Closes any FEC groups protecting packets before |sequence_number|.
   void CloseFecGroupsBefore(QuicPacketSequenceNumber sequence_number);
 
   // Sets the ping alarm to the appropriate value, if any.
   void SetPingAlarm();
 
+  // On arrival of a new packet, checks to see if the socket addresses have
+  // changed since the last packet we saw on this connection.
+  void CheckForAddressMigration(const IPEndPoint& self_address,
+                                const IPEndPoint& peer_address);
+
   QuicFramer framer_;
   QuicConnectionHelperInterface* helper_;  // Not owned.
   QuicPacketWriter* writer_;  // Not owned.
   EncryptionLevel encryption_level_;
   const QuicClock* clock_;
   QuicRandom* random_generator_;
 
   const QuicConnectionId connection_id_;
   // Address on the last successfully processed packet received from the
   // client.
   IPEndPoint self_address_;
   IPEndPoint peer_address_;
+  // Used to store latest peer port to possibly migrate to later.
+  int migrating_peer_port_;
 
   bool last_packet_revived_;  // True if the last packet was revived from FEC.
   size_t last_size_;  // Size of the last received packet.
   EncryptionLevel last_decrypted_packet_level_;
   QuicPacketHeader last_header_;
   std::vector<QuicStreamFrame> last_stream_frames_;
   std::vector<QuicAckFrame> last_ack_frames_;
   std::vector<QuicCongestionFeedbackFrame> last_congestion_frames_;
   std::vector<QuicStopWaitingFrame> last_stop_waiting_frames_;
   std::vector<QuicRstStreamFrame> last_rst_frames_;
@@ skipping 91 matching lines @@
   // The state of connection in version negotiation finite state machine.
   QuicVersionNegotiationState version_negotiation_state_;
 
   // Tracks if the connection was created by the server.
   bool is_server_;
 
   // True by default.  False if we've received or sent an explicit connection
   // close.
   bool connected_;
 
-  // Set to true if the udp packet headers have a new self or peer address.
-  // This is checked later on validating a data or version negotiation packet.
-  bool address_migrating_;
+  // Set to true if the UDP packet headers have a new IP address for the peer.
+  // If true, do not perform connection migration.
+  bool peer_ip_changed_;
+
+  // Set to true if the UDP packet headers have a new port for the peer.
+  // If true, and the IP has not changed, then we can migrate the connection.
+  bool peer_port_changed_;
+
+  // Set to true if the UDP packet headers are addressed to a different IP.
+  // We do not support connection migration when the self IP changed.
+  bool self_ip_changed_;
+
+  // Set to true if the UDP packet headers are addressed to a different port.
+  // If true, and the IP has not changed, then we can migrate the connection.

[wtc, 2014/05/13 16:37:15]

IMPORTANT: this comment doesn't match the code in
QuicConnection::ProcessValidatedPacket(). To match the code, this comment should
say:

  We do not support connection migration when the self port changed.

[Robbie Shade, 2014/05/13 21:31:21]

Correct - this comment is wrong, make the change wtc suggests.

[ramant (doing other things), 2014/05/14 05:30:23]

Made this change in
https://codereview.chromium.org/286693003/diff/1/net/quic/quic_connection.h

Done.

+  bool self_port_changed_;
 
   // If non-empty this contains the set of versions received in a
   // version negotiation packet.
   QuicVersionVector server_supported_versions_;
 
   // Initial flow control receive window size for new streams.
   uint32 max_flow_control_receive_window_bytes_;
 
   // Used for connection level flow control.
   scoped_ptr<QuicFlowController> flow_controller_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicConnection);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_CONNECTION_H_