implement port latching option

closes #119

Change-Id: I9c5f3a560088ffb04c02e1b229a2616132a506e6

README.md

@@ -717,6 +717,12 @@ Optionally included keys are:
 		This flag is valid only in an `offer` message and is useful when the call has been
 		transferred to a new endpoint without change of `From` or `To` tags.
 
+	- `port latching`
+
+		Forces *rtpengine* to retain its local ports during a signalling exchange even when the
+		remote endpoint changes its port.
+
+
 * `replace`
 
 	Similar to the `flags` list. Controls which parts of the SDP body should be rewritten.

daemon/call.c

@@ -682,7 +682,7 @@ static struct call_media *__get_media(struct call_monologue *ml, GList **it, con
 }
 
 static struct endpoint_map *__get_endpoint_map(struct call_media *media, unsigned int num_ports,
-		const struct endpoint *ep)
+		const struct endpoint *ep, const struct sdp_ng_flags *flags)
 {
 	GList *l;
 	struct endpoint_map *em;
@@ -705,13 +705,17 @@ static struct endpoint_map *__get_endpoint_map(struct call_media *media, unsigne
 		}
 		if (!ep) /* creating wildcard map */
 			break;
-		/* handle zero endpoint address */
-		if (is_addr_unspecified(&ep->address) || is_addr_unspecified(&em->endpoint.address)) {
+
+		if (flags && flags->port_latching)
+			/* do nothing - ignore endpoint addresses */ ;
+		else if (is_addr_unspecified(&ep->address) || is_addr_unspecified(&em->endpoint.address)) {
+			/* handle zero endpoint address: only compare ports */
 			if (ep->port != em->endpoint.port)
 				continue;
 		}
 		else if (memcmp(&em->endpoint, ep, sizeof(*ep)))
 			continue;
+
 		if (em->num_ports >= num_ports) {
 			if (is_addr_unspecified(&em->endpoint.address))
 				em->endpoint.address = ep->address;
@@ -809,7 +813,7 @@ static void __assign_stream_fds(struct call_media *media, GQueue *intf_sfds) {
 static int __wildcard_endpoint_map(struct call_media *media, unsigned int num_ports) {
 	struct endpoint_map *em;
 
-	em = __get_endpoint_map(media, num_ports, NULL);
+	em = __get_endpoint_map(media, num_ports, NULL, NULL);
 	if (!em)
 		return -1;
 
@@ -1632,7 +1636,7 @@ int monologue_offer_answer(struct call_monologue *other_ml, GQueue *streams,
 
 		/* get that many ports for each side, and one packet stream for each port, then
 		 * assign the ports to the streams */
-		em = __get_endpoint_map(media, num_ports, &sp->rtp_endpoint);
+		em = __get_endpoint_map(media, num_ports, &sp->rtp_endpoint, flags);
 		if (!em) {
 			goto error_ports;
 		} else {

daemon/call_interfaces.c

@@ -557,6 +557,8 @@ static void call_ng_process_flags(struct sdp_ng_flags *out, bencode_item_t *inpu
 				out->reset = 1;
 			else if (it->iov[1].iov_len >= 5 && !memcmp(it->iov[1].iov_base, "SDES-", 5))
 				ng_sdes_option(out, it, 5);
+			else if (!bencode_strcmp(it, "port-latching"))
+				out->port_latching = 1;
 			else
 				ilog(LOG_WARN, "Unknown flag encountered: '"BENCODE_FORMAT"'",
 						BENCODE_FMT(it));

daemon/call_interfaces.h

@@ -32,6 +32,7 @@ struct sdp_ng_flags {
 	int tos;
 	int asymmetric:1,
 	    trust_address:1,
+	    port_latching:1,
 	    replace_origin:1,
 	    replace_sess_conn:1,
 	    ice_remove:1,

tests/simulator-ng.pl

@@ -18,7 +18,7 @@ use SRTP;
 my ($NUM, $RUNTIME, $STREAMS, $PAYLOAD, $INTERVAL, $RTCP_INTERVAL, $STATS_INTERVAL)
 	= (1000, 30, 1, 160, 20, 5, 5);
 my ($NODEL, $IP, $IPV6, $KEEPGOING, $REINVITES, $PROTOS, $DEST, $SUITES, $NOENC, $RTCPMUX, $BUNDLE, $LAZY,
-	$CHANGE_SSRC);
+	$CHANGE_SSRC, $PORT_LATCHING);
 GetOptions(
 		'no-delete'	=> \$NODEL,
 		'num-calls=i'	=> \$NUM,
@@ -40,6 +40,7 @@ GetOptions(
 		'bundle'	=> \$BUNDLE,
 		'lazy-params'	=> \$LAZY,
 		'change-ssrc'   => \$CHANGE_SSRC,
+		'port-latching' => \$PORT_LATCHING,
 ) or die;
 
 ($IP || $IPV6) or die("at least one of --local-ip or --local-ipv6 must be given");
@@ -635,6 +636,7 @@ a=rtpmap:111 opus/48000/2
 		'received from' => [ qw(IP4 127.0.0.1) ],
 		'rtcp-mux' => ['demux'],
 	};
+	$PORT_LATCHING and push(@{$dict->{flags}}, 'port latching');
 	#$viabranch and $dict->{'via-branch'} = $viabranch;
 	if ($op eq 'offer') {
 		$dict->{'from-tag'} = $$A{tag};

utils/ng-client

@@ -43,6 +43,7 @@ GetOptions(
 	'TOS=i'				=> \$options{'TOS'},
 	'delete-delay=i'		=> \$options{'delete-delay'},
 	'reset'				=> \$options{'reset'},
+	'port-latching'			=> \$options{'port latching'},
 ) or die;
 
 my $cmd = shift(@ARGV) or die;
@@ -52,7 +53,7 @@ my %packet = (command => $cmd);
 for my $x (split(',', 'from-tag,to-tag,call-id,transport protocol,media address,ICE,address family,TOS,DTLS,via-branch,delete-delay')) {
 	defined($options{$x}) and $packet{$x} = $options{$x};
 }
-for my $x (split(',', 'trust address,symmetric,asymmetric,force,strict source,media handover,sip source address,reset')) {
+for my $x (split(',', 'trust address,symmetric,asymmetric,force,strict source,media handover,sip source address,reset,port latching')) {
 	defined($options{$x}) and push(@{$packet{flags}}, $x);
 }
 for my $x (split(',', 'origin,session connection')) {