Migrates QUIC sessions to a new network when old network is (about to be) disconnected.

net/quic/quic_chromium_client_session.cc

Index: net/quic/quic_chromium_client_session.cc
diff --git a/net/quic/quic_chromium_client_session.cc b/net/quic/quic_chromium_client_session.cc
index 0e7cb7b2debfa3fb6c163c6e23da05be8ee73fe9..6ee1c66891919c45fa6af1e5b7aa60c9a6dda237 100644
--- a/net/quic/quic_chromium_client_session.cc
+++ b/net/quic/quic_chromium_client_session.cc
@@ -40,6 +40,11 @@ const int k0RttHandshakeTimeoutMs = 300;
 // IPv6 packets have an additional 20 bytes of overhead than IPv4 packets.
 const size_t kAdditionalOverheadForIPv6 = 20;
 
+// Maximum number of Readers that are created for any session due to
+// connection migration. A new Reader is created every time this endpoint's
+// IP address changes.
+const size_t kMaxReadersPerQuicSession = 5;
+
 // Histograms for tracking down the crashes from http://crbug.com/354669
 // Note: these values must be kept in sync with the corresponding values in:
 // tools/metrics/histograms/histograms.xml
@@ -175,18 +180,19 @@ QuicChromiumClientSession::QuicChromiumClientSession(
       server_id_(server_id),
       require_confirmation_(false),
       stream_factory_(stream_factory),
-      socket_(socket.Pass()),
       transport_security_state_(transport_security_state),
       server_info_(server_info.Pass()),
       num_total_streams_(0),
       task_runner_(task_runner),
       net_log_(BoundNetLog::Make(net_log, NetLog::SOURCE_QUIC_SESSION)),
-      packet_reader_(socket_.get(), this, net_log_),
       dns_resolution_end_time_(dns_resolution_end_time),
       logger_(new QuicConnectionLogger(this, connection_description, net_log_)),
       going_away_(false),
       disabled_reason_(QUIC_DISABLED_NOT),
       weak_factory_(this) {
+  sockets_[0] = socket.Pass();

[Ryan Hamilton, 2015/09/08 04:09:37]

nit: sockets_.push_back(socket.Pass())

[Jana, 2015/11/17 01:50:08]

Done.

+  packet_readers_[0].reset(
+      new QuicPacketReader(sockets_[0].get(), this, net_log_));

[Ryan Hamilton, 2015/09/08 04:09:37]

ditto

[Jana, 2015/11/17 01:50:08]

Done.

   crypto_stream_.reset(
       crypto_client_stream_factory
           ? crypto_client_stream_factory->CreateQuicCryptoClientStream(
@@ -744,7 +750,10 @@ void QuicChromiumClientSession::OnConnectionClosed(QuicErrorCode error,
   if (!callback_.is_null()) {
     base::ResetAndReturn(&callback_).Run(ERR_QUIC_PROTOCOL_ERROR);
   }
-  socket_->Close();
+
+  for (size_t i = 0; i < sockets_.size(); ++i) {

[Ryan Hamilton, 2015/09/08 04:09:37]

nit: for (Socket socket : sockets) { ... }

[Jana, 2015/11/17 01:50:08]

Done.

+    sockets_[i]->Close();
+  }
   QuicSession::OnConnectionClosed(error, from_peer);
   DCHECK(dynamic_streams().empty());
   CloseAllStreams(ERR_UNEXPECTED);
@@ -788,7 +797,9 @@ void QuicChromiumClientSession::OnProofVerifyDetailsAvailable(
 }
 
 void QuicChromiumClientSession::StartReading() {
-  packet_reader_.StartReading();
+  for (size_t i = 0; i < packet_readers_.size(); ++i) {

[Ryan Hamilton, 2015/09/08 04:09:37]

nit: c++11 foreach loop

[Jana, 2015/11/17 01:50:08]

Done.

+    packet_readers_[i]->StartReading();
+  }
 }
 
 void QuicChromiumClientSession::CloseSessionOnError(int error,
@@ -953,4 +964,21 @@ void QuicChromiumClientSession::OnConnectTimeout() {
   //  DCHECK_EQ(0u, GetNumOpenStreams());
 }
 
+void QuicChromiumClientSession::AddSocket(
+    scoped_ptr<DatagramClientSocket> socket) {
+  size_t num_sockets = sockets_.size();
+  sockets_.resize(num_sockets + 1);
+  sockets_[num_sockets - 1] = socket.Pass();

[Ryan Hamilton, 2015/09/08 04:09:37]

I think you can just do sockets_.push_back(socket.Pass());

[Jana, 2015/11/17 01:50:08]

Done.

+}
+
+bool QuicChromiumClientSession::AddPacketReader(QuicPacketReader* reader) {
+  size_t num_readers = packet_readers_.size();
+  if (num_readers >= kMaxReadersPerQuicSession) {
+    return false;
+  }
+  packet_readers_.resize(num_readers + 1);
+  packet_readers_[num_readers - 1].reset(reader);
+  return true;
+}

[Ryan Hamilton, 2015/09/08 04:09:37]

It's a bit surprising that the AddSocket method returns void, but the AddReader
returns bool. Perhaps a single method which takes the Socket, Reader and Writer?

Should the size of readers_ and sockets_ be the same? If so, perhaps some
DCHECKs.

[Jana, 2015/11/17 01:50:08]

Yeah, this wasn't great, so I cleaned it up now, PTAL.

+
 }  // namespace net