1 files changed, 165 insertions, 0 deletions
diff --git a/src/rtpkeep.c b/src/rtpkeep.c
new file mode 100644
index 0000000..7f32c41
--- /dev/null
+++ b/src/rtpkeep.c
@@ -0,0 +1,165 @@
+/**
+ * @file rtpkeep.c  RTP Keepalive
+ *
+ * Copyright (C) 2010 Creytiv.com
+ */
+#include <re.h>
+#include <baresip.h>
+#include "core.h"
+
+
+/*
+ * See draft-ietf-avt-app-rtp-keepalive:
+ *
+ *  "zero"     4.1.  Transport Packet of 0-byte
+ *  "rtcp"     4.3.  RTCP Packets Multiplexed with RTP Packets
+ *  "stun"     4.4.  STUN Indication Packet
+ *  "dyna"     4.6.  RTP Packet with Unknown Payload Type
+ */
+
+
+enum {
+	Tr_UDP =   15,
+	Tr_TCP = 7200
+};
+
+/** RTP Keepalive */
+struct rtpkeep {
+	struct rtp_sock *rtp;
+	struct sdp_media *sdp;
+	struct tmr tmr;
+	char *method;
+	uint32_t ts;
+	bool flag;
+};
+
+
+static void destructor(void *arg)
+{
+	struct rtpkeep *rk = arg;
+
+	tmr_cancel(&rk->tmr);
+	mem_deref(rk->method);
+}
+
+
+static int send_keepalive(struct rtpkeep *rk)
+{
+	int err = 0;
+
+	if (!str_casecmp(rk->method, "zero")) {
+		struct mbuf *mb = mbuf_alloc(1);
+		if (!mb)
+			return ENOMEM;
+		err = udp_send(rtp_sock(rk->rtp),
+			       sdp_media_raddr(rk->sdp), mb);
+		mem_deref(mb);
+	}
+	else if (!str_casecmp(rk->method, "stun")) {
+		err = stun_indication(IPPROTO_UDP, rtp_sock(rk->rtp),
+				      sdp_media_raddr(rk->sdp), 0,
+				      STUN_METHOD_BINDING, NULL, 0, false, 0);
+	}
+	else if (!str_casecmp(rk->method, "dyna")) {
+		struct mbuf *mb = mbuf_alloc(RTP_HEADER_SIZE);
+		int pt = sdp_media_find_unused_pt(rk->sdp);
+		if (!mb)
+			return ENOMEM;
+		if (pt == -1)
+			return ENOENT;
+		mb->pos = mb->end = RTP_HEADER_SIZE;
+
+		err = rtp_send(rk->rtp, sdp_media_raddr(rk->sdp), false,
+			       pt, rk->ts, mb);
+
+		mem_deref(mb);
+	}
+	else if (!str_casecmp(rk->method, "rtcp")) {
+
+		if (sdp_media_rattr(rk->sdp, "rtcp-mux")) {
+			/* do nothing */
+			;
+		}
+		else {
+			warning("rtpkeep: rtcp-mux is disabled\n");
+		}
+	}
+	else {
+		warning("rtpkeep: unknown method: %s\n", rk->method);
+		return ENOSYS;
+	}
+
+	return err;
+}
+
+
+/**
+ * Logic:
+ *
+ * We check for RTP activity every 15 seconds, and clear the flag.
+ * The flag is set for every transmitted RTP packet. If the flag
+ * is not set, it means that we have not sent any RTP packet in the
+ * last period of 0 - 15 seconds. Start transmitting RTP keepalives
+ * now and every 15 seconds after that.
+ *
+ * @param arg Handler argument
+ */
+static void timeout(void *arg)
+{
+	struct rtpkeep *rk = arg;
+	int err;
+
+	tmr_start(&rk->tmr, Tr_UDP * 1000, timeout, rk);
+
+	if (rk->flag) {
+		rk->flag = false;
+		return;
+	}
+
+	err = send_keepalive(rk);
+	if (err) {
+		warning("rtpkeep: send keepalive failed: %m\n", err);
+	}
+}
+
+
+int rtpkeep_alloc(struct rtpkeep **rkp, const char *method, int proto,
+		  struct rtp_sock *rtp, struct sdp_media *sdp)
+{
+	struct rtpkeep *rk;
+	int err;
+
+	if (!rkp || !method || proto != IPPROTO_UDP || !rtp || !sdp)
+		return EINVAL;
+
+	rk = mem_zalloc(sizeof(*rk), destructor);
+	if (!rk)
+		return ENOMEM;
+
+	rk->rtp = rtp;
+	rk->sdp = sdp;
+
+	err = str_dup(&rk->method, method);
+	if (err)
+		goto out;
+
+	tmr_start(&rk->tmr, 20, timeout, rk);
+
+ out:
+	if (err)
+		mem_deref(rk);
+	else
+		*rkp = rk;
+
+	return err;
+}
+
+
+void rtpkeep_refresh(struct rtpkeep *rk, uint32_t ts)
+{
+	if (!rk)
+		return;
+
+	rk->ts = ts;
+	rk->flag = true;
+}