implement experimental passthrough relay mode

daemon/call.c

@@ -441,6 +441,8 @@ static void determine_handler(struct packet_stream *in, const struct packet_stre
 
 	if (PS_ISSET(in, HAS_HANDLER))
 		return;
+	if (MEDIA_ISSET(in->media, PASSTHRU))
+		goto noop;
 
 	if (!in->media->protocol)
 		goto err;
@@ -465,6 +467,7 @@ done:
 
 err:
 	ilog(LOG_WARNING, "Unknown transport protocol encountered");
+noop:
 	in->handler = &__sh_noop;
 	goto done;
 }
@@ -1566,6 +1569,29 @@ static int __init_streams(struct call_media *A, struct call_media *B, const stru
 	return 0;
 }
 
+static void __ice_offer(const struct sdp_ng_flags *flags, struct call_media *this,
+		struct call_media *other)
+{
+	if (!flags)
+		return;
+
+	/* we offer ICE by default */
+	if (flags->opmode == OP_OFFER) {
+		if (!MEDIA_ISSET(this, INITIALIZED))
+			MEDIA_SET(this, ICE);
+	}
+	if (flags->ice_remove)
+		MEDIA_CLEAR(this, ICE);
+
+	/* special case: if doing ICE on both sides and ice_force is not set, we cannot
+	 * be sure that media will pass through us, so we have to disable certain features */
+	if (MEDIA_ISSET(this, ICE) && MEDIA_ISSET(other, ICE) && !flags->ice_force) {
+		ilog(LOG_DEBUG, "enabling passthrough mode");
+		MEDIA_SET(this, PASSTHRU);
+		MEDIA_SET(other, PASSTHRU);
+	}
+}
+
 /* generates SDES parametes for outgoing SDP, which is our media "out" direction */
 static void __generate_crypto(const struct sdp_ng_flags *flags, struct call_media *this,
 		struct call_media *other)
@@ -1576,7 +1602,7 @@ static void __generate_crypto(const struct sdp_ng_flags *flags, struct call_medi
 	if (!flags)
 		return;
 
-	if (!this->protocol || !this->protocol->srtp) {
+	if (!this->protocol || !this->protocol->srtp || MEDIA_ISSET(this, PASSTHRU)) {
 		cp->crypto_suite = NULL;
 		MEDIA_CLEAR(this, DTLS);
 		MEDIA_CLEAR(this, SDES);
@@ -1764,7 +1790,7 @@ int monologue_offer_answer(struct call_monologue *monologue, GQueue *streams,
 
 		/* copy parameters advertised by the sender of this message */
 		bf_copy_same(&other_media->media_flags, &sp->sp_flags,
-				SP_FLAG_RTCP_MUX | SP_FLAG_ASYMMETRIC);
+				SHARED_FLAG_RTCP_MUX | SHARED_FLAG_ASYMMETRIC | SHARED_FLAG_ICE);
 
 		crypto_params_copy(&other_media->sdes_in.params, &sp->crypto);
 		other_media->sdes_in.tag = sp->sdes_tag;
@@ -1789,6 +1815,9 @@ int monologue_offer_answer(struct call_monologue *monologue, GQueue *streams,
 				&& other_media->fingerprint.hash_func)
 			MEDIA_SET(other_media, DTLS);
 
+		/* ICE negotiation */
+		__ice_offer(flags, media, other_media);
+
 		/* control rtcp-mux */
 		__rtcp_mux_logic(flags, media, other_media);
 

daemon/call.h

@@ -76,6 +76,7 @@ struct call_monologue;
 #define SHARED_FLAG_RTCP_MUX			0x00000010
 #define SHARED_FLAG_SETUP_ACTIVE		0x00000020
 #define SHARED_FLAG_SETUP_PASSIVE		0x00000040
+#define SHARED_FLAG_ICE				0x00000080
 
 /* struct stream_params */
 #define SP_FLAG_NO_RTCP				0x00010000
@@ -86,6 +87,7 @@ struct call_monologue;
 #define SP_FLAG_ASYMMETRIC			SHARED_FLAG_ASYMMETRIC
 #define SP_FLAG_SETUP_ACTIVE			SHARED_FLAG_SETUP_ACTIVE
 #define SP_FLAG_SETUP_PASSIVE			SHARED_FLAG_SETUP_PASSIVE
+#define SP_FLAG_ICE				SHARED_FLAG_ICE
 
 /* struct packet_stream */
 #define PS_FLAG_RTP				0x00010000
@@ -112,6 +114,7 @@ struct call_monologue;
 #define MEDIA_FLAG_SETUP_ACTIVE			SHARED_FLAG_SETUP_ACTIVE
 #define MEDIA_FLAG_SETUP_PASSIVE		SHARED_FLAG_SETUP_PASSIVE
 #define MEDIA_FLAG_PASSTHRU			0x00100000
+#define MEDIA_FLAG_ICE				SHARED_FLAG_ICE
 
 /* access macros */
 #define SP_ISSET(p, f)		bf_isset(&(p)->sp_flags, SP_FLAG_ ## f)

daemon/sdp.c

@@ -1031,6 +1031,10 @@ int sdp_streams(const GQueue *sessions, GQueue *streams, struct sdp_ng_flags *fl
 						sp->fingerprint.hash_func->num_bytes);
 			}
 
+			/* a=candidate */
+			if (attr_get_by_id(&media->attributes, ATTR_CANDIDATE))
+				SP_SET(sp, ICE);
+
 			/* determine RTCP endpoint */
 
 			if (attr_get_by_id(&media->attributes, ATTR_RTCP_MUX)) {
@@ -1356,23 +1360,31 @@ static int process_media_attributes(struct sdp_chopper *chop, struct sdp_media *
 			case ATTR_ICE:
 			case ATTR_ICE_UFRAG:
 			case ATTR_CANDIDATE:
+				if (MEDIA_ISSET(media, PASSTHRU))
+					break;
 				if (!flags->ice_remove && !flags->ice_force)
 					break;
 				goto strip;
 
 			case ATTR_RTCP:
 			case ATTR_RTCP_MUX:
-			case ATTR_EXTMAP:
-			case ATTR_CRYPTO:
 			case ATTR_INACTIVE:
 			case ATTR_SENDONLY:
 			case ATTR_RECVONLY:
 			case ATTR_SENDRECV:
+				goto strip;
+
+			case ATTR_EXTMAP:
+			case ATTR_CRYPTO:
 			case ATTR_FINGERPRINT:
 			case ATTR_SETUP:
+				if (MEDIA_ISSET(media, PASSTHRU))
+					break;
 				goto strip;
 
 			case ATTR_MID:
+				if (MEDIA_ISSET(media, PASSTHRU))
+					break;
 				a = attr_get_by_id(&sdp->session->attributes, ATTR_GROUP);
 				if (a && a->u.group.semantics == GROUP_BUNDLE)
 					goto strip;
@@ -1499,7 +1511,7 @@ static void insert_dtls(struct call_media *media, struct sdp_chopper *chop) {
 	const char *actpass;
 	struct call *call = media->call;
 
-	if (!call->dtls_cert || !MEDIA_ISSET(media, DTLS))
+	if (!call->dtls_cert || !MEDIA_ISSET(media, DTLS) || MEDIA_ISSET(media, PASSTHRU))
 		return;
 
 	hf = call->dtls_cert->fingerprint.hash_func;
@@ -1538,7 +1550,7 @@ static void insert_crypto(struct call_media *media, struct sdp_chopper *chop) {
 	struct crypto_params *cp = &media->sdes_out.params;
 	unsigned long long ull;
 
-	if (!cp->crypto_suite || !MEDIA_ISSET(media, SDES))
+	if (!cp->crypto_suite || !MEDIA_ISSET(media, SDES) || MEDIA_ISSET(media, PASSTHRU))
 		return;
 
 	p = b64_buf;
@@ -1616,12 +1628,14 @@ int sdp_replace(struct sdp_chopper *chop, GQueue *sessions, struct call_monologu
 				goto error;
 		}
 
-		if (process_session_attributes(chop, &session->attributes, flags))
-			goto error;
+		if (!MEDIA_ISSET(call_media, PASSTHRU)) {
+			if (process_session_attributes(chop, &session->attributes, flags))
+				goto error;
 
-		if (do_ice) {
-			copy_up_to_end_of(chop, &session->s);
-			chopper_append_c(chop, "a=ice-lite\r\n");
+			if (do_ice) {
+				copy_up_to_end_of(chop, &session->s);
+				chopper_append_c(chop, "a=ice-lite\r\n");
+			}
 		}
 
 		media_index = 1;
@@ -1696,7 +1710,7 @@ int sdp_replace(struct sdp_chopper *chop, GQueue *sessions, struct call_monologu
 			insert_crypto(call_media, chop);
 			insert_dtls(call_media, chop);
 
-			if (do_ice) {
+			if (do_ice && !MEDIA_ISSET(call_media, PASSTHRU)) {
 				if (!call_media->ice_ufrag.s) {
 					create_random_ice_string(call, &call_media->ice_ufrag, 8);
 					create_random_ice_string(call, &call_media->ice_pwd, 28);