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

net/udp/udp_client_socket.cc

 // Copyright (c) 2011 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/udp/udp_client_socket.h"
 
 #include "net/base/net_errors.h"
 #include "net/log/net_log.h"
 
 namespace net {
 
 UDPClientSocket::UDPClientSocket(DatagramSocket::BindType bind_type,
                                  const RandIntCallback& rand_int_cb,
                                  net::NetLog* net_log,
                                  const net::NetLog::Source& source)
     : socket_(bind_type, rand_int_cb, net_log, source) {
 }
 
 UDPClientSocket::~UDPClientSocket() {
 }
 
 int UDPClientSocket::BindToNetwork(
     NetworkChangeNotifier::NetworkHandle network) {
   return socket_.BindToNetwork(network);
 }
 
+int UDPClientSocket::BindToDefaultNetwork() {
+  NetworkChangeNotifier::NetworkHandle network = 
+      NetworkChangeNotifier::GetDefaultNetwork();
+  return BindToNetwork(network);

[pauljensen, 2015/10/19 19:01:39]

The reason this needs to loop is that the default network can change, so this is
racy.  The idea is to do something like:
int ret;
for (int attempt = 0; attempt < 3; attempt++) {
  NetworkChangeNotifier::NetworkHandle network =
      NetworkChangeNotifier::GetDefaultNetwork();
  if (network == kInvalidNetworkHandle)
    return ERR_INTERNET_DISCONNECTED;
  ret = BindToNetwork(network);
  if (ret != /*whatever ENONET turns into*/)
    return ret;
}
return ret;

You can see we return ENONET when we try to bind a socket to a network that no
longer exists here in Android:
http://androidxref.com/6.0.0_r1/xref/system/netd/server/NetworkController.cpp...

[pauljensen, 2015/10/19 19:49:04]

This incorrectly returns ERR_INTERNET_DISCONNECTED however when
GetDefaultNetwork isn't implemented however...hmm

[Jana, 2015/11/17 01:50:09]

Let's continue this conversation on your CL to implement BindToDefaultNetwork.
I'm leaving this simple implementation as is, to be replaced by your
implementation. SG?

+}
+
 int UDPClientSocket::Connect(const IPEndPoint& address) {
   int rv = socket_.Open(address.GetFamily());
   if (rv != OK)
     return rv;
   return socket_.Connect(address);
 }
 
 int UDPClientSocket::Read(IOBuffer* buf,
                           int buf_len,
                           const CompletionCallback& callback) {
@@ skipping 30 matching lines @@
   return socket_.NetLog();
 }
 
 #if defined(OS_WIN)
 void UDPClientSocket::UseNonBlockingIO() {
   socket_.UseNonBlockingIO();
 }
 #endif
 
 }  // namespace net