Adding PortAllocator option to support cases where sockets can't be bound.

webrtc/p2p/base/basicpacketsocketfactory.cc

 /*
  *  Copyright 2011 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 96 matching lines @@
 AsyncPacketSocket* BasicPacketSocketFactory::CreateClientTcpSocket(
     const SocketAddress& local_address, const SocketAddress& remote_address,
     const ProxyInfo& proxy_info, const std::string& user_agent, int opts) {
   AsyncSocket* socket =
       socket_factory()->CreateAsyncSocket(local_address.family(), SOCK_STREAM);
   if (!socket) {
     return NULL;
   }
 
   if (BindSocket(socket, local_address, 0, 0) < 0) {
-    LOG(LS_ERROR) << "TCP bind failed with error "
-                  << socket->GetError();
-    delete socket;
-    return NULL;
+    // Allow BindSocket to fail if we're binding to the ANY address anyway. The

[pthatcher1, 2017/06/13 19:52:50]

Not sure what "anyway" adds to the end of the sentence.  It seems like you could
remove it.

[Taylor Brandstetter, 2017/06/13 22:11:17]

Rephrased comment.

+    // socket will be bound when we call Connect() instead.
+    if (local_address.IsAnyIP()) {
+      LOG(LS_WARNING) << "TCP bind failed with error " << socket->GetError()
+                      << "; ignoring since socket is using 'any' address.";

[pthatcher1, 2017/06/13 19:52:49]

Can you use an early return and then leave the rest of the code outside of the
else block?

[Taylor Brandstetter, 2017/06/13 22:11:17]

I knew you would ask for an early return here. :)

And that's how I wrote the code originally, but it's notably less readable that
way; not worth removing a level of indentation imo.

+    } else {
+      LOG(LS_ERROR) << "TCP bind failed with error " << socket->GetError();
+      delete socket;
+      return NULL;
+    }
   }
 
   // If using a proxy, wrap the socket in a proxy socket.
   if (proxy_info.type == PROXY_SOCKS5) {
     socket = new AsyncSocksProxySocket(
         socket, proxy_info.address, proxy_info.username, proxy_info.password);
   } else if (proxy_info.type == PROXY_HTTPS) {
     socket =
         new AsyncHttpsProxySocket(socket, user_agent, proxy_info.address,
                                   proxy_info.username, proxy_info.password);
@@ skipping 75 matching lines @@
 SocketFactory* BasicPacketSocketFactory::socket_factory() {
   if (thread_) {
     RTC_DCHECK(thread_ == Thread::Current());
     return thread_->socketserver();
   } else {
     return socket_factory_;
   }
 }
 
 }  // namespace rtc