Add the new SDP section to the MNCC socket protocol, but do not yet implement
forwarding SDP from SIP. Implementing SDP forwarding follows in a subsequent
patch.
It is still possible to establish a call with empty SDP: the new osmo-msc on
the MT side, receiving an MNCC_SETUP_REQ, will hit an error log:
"Got no information of remote audio codecs: neither SDP nor Bearer Capability.
Trying anyway."
and then hold thumbs to hit a codec match, analogous to previous behavior.
Note that osmo-sip-connector should actually always have encoded a Bearer
Capability in the MNCC protocol in the MT MNCC_SETUP_REQ message, but never
has. Now we are ready to leapfrog from zero codec info to full SDP.
This patch must be merged at the same time as osmo-msc patch
Ie16f0804c4d99760cd4a0c544d0889b6313eebb7, so that both sides have a matching
MNCC protocol version number.
Change-Id: Iaca9ed6611fc5ca8ca749bbbefc31f54bea5e925
2e2db3e0ad