mgw: Configure IuUP if codec set during MDCX

The mgcp client may first configure the connection to use RTP-AMR, but
after setting up another call leg may find out that both legs are IuUP
and hence want to forward the IuUP between the 2 connections instead.
In that case, an MDCX with codec VND.3GPP.IUFP would be set.

Until now, osmo-mgw didn't take that scenario into account, and it was
only upgrading the rtp conn to iuup internally during CRCX.
As a result, in the mentioned scenario osmo-mgw would continue to
output RTP instead of IuUP after the MDCX with VND.3GPP.IUFP, which is
wrong.

Related: SYS#6578
Change-Id: Ic94bf90f54d8ba3e65a2cd52734867847f3a60c2
---
M src/libosmo-mgcp/mgcp_protocol.c
1 file changed, 25 insertions(+), 0 deletions(-)

diff --git a/src/libosmo-mgcp/mgcp_protocol.c b/src/libosmo-mgcp/mgcp_protocol.c
index 7795734..809622b 100644
--- a/src/libosmo-mgcp/mgcp_protocol.c
+++ b/src/libosmo-mgcp/mgcp_protocol.c
@@ -1293,6 +1293,10 @@
 		error_code = rc;
 		goto error3;
 	}
+	/* Upgrade the conn type RTP_DEFAULT->RTP_IUUP if needed based on requested codec: */
+	/* TODO: "codec" probably needs to be moved from endp to conn */
+	if (conn->type == MGCP_RTP_DEFAULT && strcmp(conn->end.codec->subtype_name, "VND.3GPP.IUFP") == 0)
+		rc = mgcp_conn_iuup_init(conn);
 
 	/* check connection mode setting */
 	if (conn->conn->mode != MGCP_CONN_LOOPBACK

