MT#55283 add SDES-prefer option

Change-Id: I8c90c68a2c1a093d0a017d1edb6cac9b2f0bc5a1

daemon/call.c

@@ -2104,6 +2104,16 @@ static void __dtls_logic(const struct sdp_ng_flags *flags,
 			&sp->sp_flags, SP_FLAG_SETUP_PASSIVE);
 
 	if (flags) {
+		/* Allow overriding preference of DTLS over SDES */
+		if ((flags->opmode == OP_OFFER || flags->opmode == OP_PUBLISH)
+				&& flags->sdes_prefer
+				&& MEDIA_ISSET(other_media, SDES))
+		{
+			MEDIA_CLEAR(other_media, DTLS);
+			MEDIA_CLEAR(other_media, SETUP_ACTIVE);
+			MEDIA_CLEAR(other_media, SETUP_PASSIVE);
+		}
+
 		/* Special case: if this is an offer and actpass is being offered (as it should),
 		 * we would normally choose to be active. However, if this is a reinvite and we
 		 * were passive previously, we should retain this role. */

daemon/call_interfaces.c

@@ -561,6 +561,10 @@ INLINE void ng_sdes_option(struct sdp_ng_flags *out, str *s, void *dummy) {
 		case CSH_LOOKUP("nonew"):
 			out->sdes_nonew = 1;
 			break;
+		case CSH_LOOKUP("prefer"):
+		case CSH_LOOKUP("priority"):
+			out->sdes_prefer = 1;
+			break;
 		default:
 			ilog(LOG_WARN, "Unknown 'SDES' flag encountered: '"STR_FORMAT"'",
 					STR_FMT(s));

docs/ng_control_protocol.md

@@ -637,6 +637,14 @@ Optionally included keys are:
 		and instead leave the previously negotiated crypto suite in place. Only useful in
 		subsequent `answer` messages and ignored in `offer` messages.
 
+	- `prefer`
+
+        If an `offer` or `publish` contain both DTLS and SDES options, by
+        default *rtpengine* prefers DTLS over SDES and would end up accepting
+        DTLS. With this option set, in this scenario SDES would be preferred
+        and accepted, while DTLS would be rejected. Useful in combination with
+        `DTLS=off`.
+
 * `supports`
 
 	Contains a list of strings. Each string indicates support for an additional feature

include/call_interfaces.h

@@ -195,6 +195,7 @@ struct sdp_ng_flags {
 	             sdes_pad:1,
 	             sdes_static:1,
 	             sdes_nonew:1,
+	             sdes_prefer:1,
 	             drop_traffic_start:1,
 	             drop_traffic_stop:1,
 	             passthrough_on:1,