Fix AllocationSequence to handle the case when TurnPort stops using shared socket.

webrtc/p2p/client/basicportallocator.cc

Index: webrtc/p2p/client/basicportallocator.cc
diff --git a/webrtc/p2p/client/basicportallocator.cc b/webrtc/p2p/client/basicportallocator.cc
index 22abf33e93639d90b276ca9d6c5cc025fca3a6e0..ae79aea26872bdda92a7a83cbc66f6b1489b4873 100644
--- a/webrtc/p2p/client/basicportallocator.cc
+++ b/webrtc/p2p/client/basicportallocator.cc
@@ -1083,7 +1083,7 @@ void AllocationSequence::OnReadPacket(
   for (std::vector<TurnPort*>::const_iterator it = turn_ports_.begin();
        it != turn_ports_.end(); ++it) {
     TurnPort* port = *it;
-    if (port->server_address().address == remote_addr) {
+    if (port->SharedSocket() && port->server_address().address == remote_addr) {

[honghaiz, 2016/04/19 05:32:20]

I think it is better to still let the TurnPort eat the packet if the server
address matches and the port is not using Shared socket. With the current
change, if the server address matches and the port is not using shared socket,
the packet will be passed to the stun port, which is unexpected. 

So I suggest instead of changing here, you can change the
TurnPort::HandleIncomingPacket method, 
in which if the port is using shared socket, pass it to OnReadPacket, otherwise,
drop it. 

[Sergey Ulanov, 2016/04/20 20:50:56]

The packet will be passed to a stun port only when the remote address is in the
list of stun servers. Also, according the comment above there is a case when
STUN and TURN servers share the same address. In that case I think we actually
want the packet to be passed to the stun port.

BTW the comment doesn't make it clear what's the right behavior when we receive
a STUN binding response here. If I understand correctly we want that packet be
passed to StunPort, but currently this code gives it to the TurnPort and assumes
that it was handled there.
Move all code from OnReadPacket() to HandleIncomingPacket(). This allows to
return correct result from HandleIncomingPacket() and so STUN binding responses
are now passed to STUN port as they should.

[honghaiz3, 2016/04/22 01:49:02]

It will be passed to the stun port because the condition was 
if (not found in the turn server list OR it is found in the stun server list).  
Yes, we want that packet to be passed to StunPort. 
I think the existing code is doing that because of the OR condition. 

       port->HandleIncomingPacket(socket, data, size, remote_addr, packet_time);
       turn_port_found = true;
       break;
@@ -1097,6 +1097,7 @@ void AllocationSequence::OnReadPacket(
     // the TURN server is also a STUN server.
     if (!turn_port_found ||
         stun_servers.find(remote_addr) != stun_servers.end()) {
+      RTC_DCHECK(udp_port_->SharedSocket());
       udp_port_->HandleIncomingPacket(
           socket, data, size, remote_addr, packet_time);
     }