From a608d8bd690e6660da70e5fecd6868bd910a95c2 Mon Sep 17 00:00:00 2001
From: Richard Aas <richard@db.org>
Date: Sun, 5 Dec 2010 15:44:23 +0000
Subject: [PATCH] RFC 5761 - Multiplexing RTP Data and Control Packets on a
 Single Port

---
 docs/README      |  1 +
 include/re_rtp.h |  1 +
 src/rtp/rtp.c    | 38 +++++++++++++++++++++++++++++---------
 3 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/docs/README b/docs/README
index ff76202..ded92a9 100644
--- a/docs/README
+++ b/docs/README
@@ -95,6 +95,7 @@ Features:
 * RFC 5118 - SIP Torture Test Messages for IPv6
 * RFC 5245 - Interactive Connectivity Establishment (ICE)
 * RFC 5389 - Session Traversal Utilities for NAT (STUN)
+* RFC 5761 - Multiplexing RTP Data and Control Packets on a Single Port
 * RFC 5766 - Traversal Using Relays around NAT (TURN)
 * RFC 5768 - Indicating Support for ICE in SIP
 * RFC 5769 - Test vectors for STUN
diff --git a/include/re_rtp.h b/include/re_rtp.h
index ed06c75..fcd5cd9 100644
--- a/include/re_rtp.h
+++ b/include/re_rtp.h
@@ -212,6 +212,7 @@ const struct sa *rtp_local(const struct rtp_sock *rs);
 /* RTCP session api */
 void  rtcp_start(struct rtp_sock *rs, const char *cname,
 		 const struct sa *peer);
+void  rtcp_enable_mux(struct rtp_sock *rs, bool enabled);
 void  rtcp_set_srate(struct rtp_sock *rs, uint32_t sr_tx, uint32_t sr_rx);
 int   rtcp_send_app(struct rtp_sock *rs, const char name[4],
 		    const uint8_t *data, size_t len);
diff --git a/src/rtp/rtp.c b/src/rtp/rtp.c
index 56f6a97..450db42 100644
--- a/src/rtp/rtp.c
+++ b/src/rtp/rtp.c
@@ -38,6 +38,7 @@ struct rtp_sock {
 	rtcp_recv_h *rtcph;
 	void *arg;
 	struct rtcp_sess *rtcp;
+	bool rtcp_mux;
 };
 
 
@@ -167,18 +168,27 @@ static void udp_recv_handler(const struct sa *src, struct mbuf *mb, void *arg)
 {
 	struct rtp_sock *rs = arg;
 	struct rtp_header hdr;
-	size_t pos;
 	int err;
 
-	pos = mb->pos;
-	err = rtp_decode(rs, mb, &hdr);
-	if (err) {
-		/* Not an RTP packet - try RTCP */
-		mb->pos = pos;
-		rtcp_recv_handler(src, mb, arg);
-		return;
+	/* Handle RTCP multiplexed on RTP-port */
+	if (rs->rtcp_mux) {
+		uint8_t pt;
+
+		if (mbuf_get_left(mb) < 2)
+			return;
+
+		pt = mbuf_buf(mb)[1] & 0x7f;
+
+		if (64 <= pt && pt <= 95) {
+			rtcp_recv_handler(src, mb, arg);
+			return;
+		}
 	}
 
+	err = rtp_decode(rs, mb, &hdr);
+	if (err)
+		return;
+
 	if (rs->rtcp) {
 		rtcp_sess_rx_rtp(rs->rtcp, hdr.seq, hdr.ts,
 				 hdr.ssrc, mbuf_get_left(mb), src);
@@ -444,12 +454,22 @@ void rtcp_start(struct rtp_sock *rs, const char *cname,
 }
 
 
+void rtcp_enable_mux(struct rtp_sock *rs, bool enabled)
+{
+	if (!rs)
+		return;
+
+	rs->rtcp_mux = enabled;
+}
+
+
 int rtcp_send(struct rtp_sock *rs, struct mbuf *mb)
 {
 	if (!rs || !rs->sock_rtcp || !sa_isset(&rs->rtcp_peer, SA_ALL))
 		return EINVAL;
 
-	return udp_send(rs->sock_rtcp, &rs->rtcp_peer, mb);
+	return udp_send(rs->rtcp_mux ? rs->sock_rtp : rs->sock_rtcp,
+			&rs->rtcp_peer, mb);
 }