codecs[] is an array of enum osmo_mgcp_codecs.
ptmap[] is an array of { enum osmo_mgcp_codecs, unsigned int ptmap }.
MGCP lists first a bunch of payload type numbers and then specifies them
again for details, like the numbers 112, 96, 3 in this example:
m=audio <port> RTP/AVP 112 96 3
a=rtpmap:112 AMR/8000
a=rtpmap:96 VND.3GPP.IUFP/16000
a=rtpmap:3 GSM-FR/8000
So far we keep these lists in two separate arrays:
- codecs[], codecs_len stores the 'm=audio' list
- ptmap[], ptmap_len stores the 'a=rtpmap' list (and may omit some
elements present in codecs[])
This applies to both struct mgcp_response and struct mgcp_msg.
These are semantically identical, and the separation leads to checks,
conversions and dear hopes of correct ordering.
So let's keep only one list with both codec and payload type number in
it. The 'm=audio' list establishes the order of the pt numbers, and the
'a=rtpmap' list adds codec information to the established entries.
In the internal API structs mgcp_msg and mgcp_response, just drop the
codecs[] entirely.
In public API struct mgcp_conn_peer, keep the codecs[] array, mark it
deprecated, and provide a backwards compat conversion: if any caller
invokes mgcp_conn_create() or mgcp_conn_modify() with codecs[] still
present in the verb_info arg, then move codecs[] entries over to the
ptmap[] array in a sensible way.
(BTW, even mgcp_conn_create() and mgcp_conn_modify() are never called
from outside of libosmo-mgcp-client in any of our osmo-cni programs;
users call osmo_mgcpc_ep_ci_add() and osmo_mgcpc_ep_ci_request(), which
in turn may pass user-provided codecs[] lists on to mgcp_conn_create() or
mgcp_conn_modify().)
Tests for parsing the MGCP response are mostly missing. They will be
added in upcoming patch I842ce65a9a70f313570857b7df53727cc572b9e6,
because they will be using only the new ptmap API.
Related: OS#6171
Change-Id: I798e02c6663376d3d52f4a74fc4b32411ce95bed
Neels Hofmeyr
cc2f7937ed