Fallback to IPv6 if IPv4 adb port not available.

chrome/test/chromedriver/net/adb_client_socket.cc

 // Copyright (c) 2013 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 "chrome/test/chromedriver/net/adb_client_socket.h"
 
 #include <stddef.h>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 349 matching lines @@
 }
 
 AdbClientSocket::AdbClientSocket(int port) : port_(port) {}
 
 AdbClientSocket::~AdbClientSocket() {
 }
 
 void AdbClientSocket::Connect(const net::CompletionCallback& callback) {
   net::AddressList address_list = net::AddressList::CreateFromIPAddress(
       net::IPAddress::IPv4Localhost(), port_);
   socket_.reset(new net::TCPClientSocket(address_list, NULL, NULL,

[pmarks, 2016/09/20 00:42:13]

It looks like TCPClientSocket already supports connecting to a list of IP
addresses.  Can you pass it a list instead of implementing your own fallback?

[lepton, 2016/09/20 08:04:11]

Done.

                                          net::NetLog::Source()));
   int result = socket_->Connect(callback);
+  if (result == net::ERR_ADDRESS_UNREACHABLE) {
+      VLOG(0) << "connect to IPv4 failed, trying IPv6";
+      address_list =
+          net::AddressList::CreateFromIPAddress(net::IPAddress::IPv6Localhost(),
+                                                port_);
+      socket_.reset(new net::TCPClientSocket(address_list, NULL, NULL,
+                                             net::NetLog::Source()));
+      result = socket_->Connect(callback);
+  }
   if (result != net::ERR_IO_PENDING)
     callback.Run(result);
 }
 
 void AdbClientSocket::SendCommand(const std::string& command,
                                   bool is_void,
                                   bool has_length,
                                   const CommandCallback& callback) {
   scoped_refptr<net::StringIOBuffer> request_buffer =
       new net::StringIOBuffer(EncodeMessage(command));
@@ skipping 143 matching lines @@
                                     base::Unretained(this),
                                     callback,
                                     new_response,
                                     response_buffer,
                                     bytes_left));
   if (result > 0)
     OnResponseData(callback, new_response, response_buffer, bytes_left, result);
   else if (result != net::ERR_IO_PENDING)
     callback.Run(net::OK, new_response);
 }