fix 3G hack: allow any IP for loopback and 0.0.0.0

HACK: for IuUP, we want to reply with an IuUP Initialization ACK upon the first RTP
message received. We currently hackishly accomplish that by putting the endpoint in
loopback mode and patching over the looped back RTP message to make it look like an
ack. We don't know the femto cell's IP address and port until the RAB Assignment
Response is received, but the nano3G expects an IuUP Initialization Ack before it even
sends the RAB Assignment Response. Hence, if the remote address is 0.0.0.0 and the
MGCP port is in loopback mode, allow looping back the packet to any source.

None of these are anything near nice, during call setup using a 3G femto cell,
we still lack a proper IuUP handling. See OS#2459, OS#1937. This is merely a
temporary hack to maintain 3G voice usability in a quick and dirty way.

Related: OS#3411
Change-Id: Ib25e6261855eae8ddb8d1c0b8838cc3e30332cf1
1 file changed