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/**
* @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,
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;
}
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