mgcp/sdp: Session name must not be empty pick an empty one
The session name must be present in a SDP file. The RFC proposes
to use a space for it but the other equipment is using the dash
so I have picked that as well.
RFC 4566:
The "s=" field is the textual session name. There MUST be one and
only one "s=" field per session description. The "s=" field MUST NOT
be empty and SHOULD contain ISO 10646 characters (but see also the
"a=charset" attribute). If a session has no meaningful name, the
alue "s= " SHOULD be used (i.e., a single space as the session
name).
Fixes: RT#2196
diff --git a/openbsc/src/libmgcp/mgcp_protocol.c b/openbsc/src/libmgcp/mgcp_protocol.c
index 98452ce..5df3577 100644
--- a/openbsc/src/libmgcp/mgcp_protocol.c
+++ b/openbsc/src/libmgcp/mgcp_protocol.c
@@ -258,6 +258,7 @@
len = snprintf(sdp_record, size,
"v=0\r\n"
"o=- %u 23 IN IP4 %s\r\n"
+ "s=-\r\n"
"c=IN IP4 %s\r\n"
"t=0 0\r\n",
endp->ci, addr, addr);