MT#55283 ignore ICE=force for answer SDPs

It doesn't make sense to produce an answer SDP with ICE attributes (and
enabling ICE processing) if the offer didn't indicate ICE support.

Closes #2106

Change-Id: I7cc6083beffc3f76f34c965049e8179866df2e6f
(cherry picked from commit eb108705b2)

daemon/call.c

@@ -1431,8 +1431,10 @@ static void __ice_offer(const sdp_ng_flags *flags, struct call_media *this,
 	// unless instructed not to
 	if (flags->ice_option == ICE_REMOVE)
 		MEDIA_CLEAR(this, ICE);
-	else if (flags->ice_option != ICE_DEFAULT)
-		MEDIA_SET(this, ICE);
+	else if (flags->ice_option != ICE_DEFAULT) {
+		if (flags->opmode != OP_ANSWER && flags->opmode != OP_PUBLISH)
+			MEDIA_SET(this, ICE);
+	}
 
 	if (flags->ice_reject)
 		MEDIA_CLEAR(other, ICE);

t/auto-daemon-tests.pl

@@ -1139,6 +1139,51 @@ rcv($sock_b, $port_a, rtpm(98 | 0x80, 7003, 9480, 0x75336ce, "\x08\x0f\x00\xa0")
 
 
 
+new_call;
+
+offer('ICE=force in answer', { }, <<SDP);
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.1
+s=tester
+t=0 0
+m=audio 2000 RTP/AVP 0
+c=IN IP4 198.51.100.14
+a=sendrecv
+----------------------------------
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.1
+s=tester
+t=0 0
+m=audio PORT RTP/AVP 0
+c=IN IP4 203.0.113.1
+a=rtpmap:0 PCMU/8000
+a=sendrecv
+a=rtcp:PORT
+SDP
+
+answer('ICE=force in answer', { ICE => 'force'}, <<SDP);
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.1
+s=tester
+t=0 0
+m=audio 2000 RTP/AVP 0
+c=IN IP4 198.51.100.14
+a=sendrecv
+----------------------------------
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.1
+s=tester
+t=0 0
+m=audio PORT RTP/AVP 0
+c=IN IP4 203.0.113.1
+a=rtpmap:0 PCMU/8000
+a=sendrecv
+a=rtcp:PORT
+SDP
+
+
+
+
 ($sock_a, $sock_b) = new_call([qw(198.51.100.1 7256)], [qw(198.51.100.3 7258)]);
 
 ($port_a, undef, $ufrag_a, $pwd_a) = offer('remote-candidates', { 'rtcp-mux' => ['require'] }, <<SDP);