Jakub Adam authored Feb 03, 2018 and Olivier Crête committed Mar 23, 2018

If main SfB TURN server sends our allocation request to an alternate
server, the response will have XOR_MAPPED_ADDRESS containing the IP
address of the turn server that proxied the message instead of our own
actual external IP.

Before we create server reflexive candidates upon receiving an allocate
response, check that the TURN port got assigned on the same server we
sent out allocate request to. Otherwise, the request was proxied and
XOR_MAPPED_ADDRESS contains a bogus value we should ignore.

Issue introduced by 59fcf95d.
Differential Revision: https://phabricator.freedesktop.org/D1949