TT#29151 add 'loop protect' feature

possible fix for: #431, #425, #415, #65

Change-Id: I12558681b7d292e3973d2ba024f30f1e236b3a57

README.md

@@ -1015,6 +1015,14 @@ Optionally included keys are:
 
 		Omit the `a=rtcp` line from the outgoing SDP.
 
+	- `loop protect`
+
+		Inserts a custom attribute (`a=rtpengine:...`) into the outgoing SDP to prevent *rtpengine*
+		processing and rewriting the same SDP multiple times. This is useful if your setup
+		involves signalling loops and need to make sure that *rtpengine* doesn't start looping
+		media packets back to itself. When this flag is present and *rtpengine* sees a matching
+		attribute already present in the SDP, it will leave the SDP untouched and not process
+		the message.
 
 * `replace`
 

daemon/call_interfaces.c

@@ -608,6 +608,8 @@ static void call_ng_flags_flags(struct sdp_ng_flags *out, str *s, void *dummy) {
 		out->record_call = 1;
 	else if (!str_cmp(s, "no-rtcp-attribute"))
 		out->no_rtcp_attr = 1;
+	else if (!str_cmp(s, "loop-protect"))
+		out->loop_protect = 1;
 	else {
 		// handle values aliases from other dictionaries
 		if (call_ng_flags_prefix(out, s, "SDES-", ng_sdes_option, NULL))
@@ -734,6 +736,13 @@ static const char *call_offer_answer_ng(bencode_item_t *input,
 	call_ng_process_flags(&flags, input);
 	flags.opmode = opmode;
 
+	if (flags.loop_protect && sdp_is_duplicate(&parsed)) {
+		ilog(LOG_INFO, "Ignoring message as SDP has already been processed by us");
+		bencode_dictionary_add_str(output, "sdp", &sdp);
+		errstr = NULL;
+		goto out;
+	}
+
 	errstr = "Incomplete SDP specification";
 	if (sdp_streams(&parsed, &streams, &flags))
 		goto out;

daemon/call_interfaces.h

@@ -54,6 +54,7 @@ struct sdp_ng_flags {
 	    dtls_passive:1,
 	    reset:1,
 	    record_call:1,
+	    loop_protect:1,
 	    dtls_off:1,
 	    sdes_off:1,
 	    sdes_unencrypted_srtp:1,

daemon/sdp.c

@@ -201,6 +201,7 @@ struct sdp_attribute {
 		ATTR_RTPMAP,
 		ATTR_FMTP,
 		ATTR_IGNORE,
+		ATTR_RTPENGINE,
 		ATTR_END_OF_CANDIDATES,
 	} attr;
 
@@ -219,6 +220,11 @@ struct sdp_attribute {
 
 
 
+static char __id_buf[6*2 + 1]; // 6 hex encoded characters
+static const str instance_id = STR_CONST_INIT(__id_buf);
+
+
+
 
 INLINE struct sdp_attribute *attr_get_by_id(struct sdp_attributes *a, int id) {
 	return g_hash_table_lookup(a->id_hash, &id);
@@ -854,6 +860,8 @@ static int parse_attribute(struct sdp_attribute *a) {
 				ret = parse_attribute_candidate(a);
 			else if (!str_cmp(&a->name, "ice-ufrag"))
 				a->attr = ATTR_ICE_UFRAG;
+			else if (!str_cmp(&a->name, "rtpengine"))
+				a->attr = ATTR_RTPENGINE;
 			break;
 		case 11:
 			if (!str_cmp(&a->name, "ice-options"))
@@ -2005,6 +2013,14 @@ int sdp_replace(struct sdp_chopper *chop, GQueue *sessions, struct call_monologu
 				goto error;
 		}
 
+		copy_up_to_end_of(chop, &session->s);
+
+		if (flags->loop_protect) {
+			chopper_append_c(chop, "a=rtpengine:");
+			chopper_append_str(chop, &instance_id);
+			chopper_append_c(chop, "\r\n");
+		}
+
 		media_index = 1;
 
 		for (k = session->media_streams.head; k; k = k->next) {
@@ -2126,5 +2142,24 @@ error:
 	return -1;
 }
 
+int sdp_is_duplicate(GQueue *sessions) {
+	for (GList *l = sessions->head; l; l = l->next) {
+		struct sdp_session *s = l->data;
+		GQueue *attr_list = attr_list_get_by_id(&s->attributes, ATTR_RTPENGINE);
+		if (!attr_list)
+			return 0;
+		for (GList *ql = attr_list->head; ql; ql = ql->next) {
+			struct sdp_attribute *attr = ql->data;
+			if (!str_cmp_str(&attr->value, &instance_id))
+				goto next;
+		}
+		return 0;
+next:
+		;
+	}
+	return 1;
+}
+
 void sdp_init() {
+	rand_hex_str(instance_id.s, instance_id.len / 2);
 }

daemon/sdp.h

@@ -22,6 +22,7 @@ int sdp_parse(str *body, GQueue *sessions);
 int sdp_streams(const GQueue *sessions, GQueue *streams, struct sdp_ng_flags *);
 void sdp_free(GQueue *sessions);
 int sdp_replace(struct sdp_chopper *, GQueue *, struct call_monologue *, struct sdp_ng_flags *);
+int sdp_is_duplicate(GQueue *sessions);
 
 struct sdp_chopper *sdp_chopper_new(str *input);
 void sdp_chopper_destroy(struct sdp_chopper *chop);

utils/rtpengine-ng-client

@@ -43,6 +43,7 @@ GetOptions(
 	'delete-delay=i'		=> \$options{'delete-delay'},
 	'reset'				=> \$options{'reset'},
 	'port-latching'			=> \$options{'port latching'},
+	'loop-protect'			=> \$options{'loop protect'},
 	'media-address=s'		=> \$options{'media address'},
 	'codec-strip=s@'		=> \$options{'codec-strip'},
 	'codec-offer=s@'		=> \$options{'codec-offer'},
@@ -59,7 +60,7 @@ for my $x (split(/,/, 'from-tag,to-tag,call-id,transport protocol,media address,
 for my $x (split(/,/, 'TOS,delete-delay')) {
 	defined($options{$x}) and $packet{$x} = $options{$x};
 }
-for my $x (split(/,/, 'trust address,symmetric,asymmetric,force,strict source,media handover,sip source address,reset,port latching,no rtcp attribute')) {
+for my $x (split(/,/, 'trust address,symmetric,asymmetric,force,strict source,media handover,sip source address,reset,port latching,no rtcp attribute,loop protect')) {
 	defined($options{$x}) and push(@{$packet{flags}}, $x);
 }
 for my $x (split(/,/, 'origin,session connection')) {