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module-rtp-sap: implement IGMP recovery for multicast subscription loss

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Add IGMP recovery mechanism that monitors SAP packet reception and
triggers multicast group refresh when no packets are received if
a deadline is reached. The deadline is set to half of the cleanup
interval, with a minimum of 1 second.

When the deadline is reached, the mechanism performs IGMP leave/rejoin
operations to refresh multicast group membership. This ensures SAP
announcements continue to be received when network conditions cause
IGMP membership to expire or become stale due to router timeouts or
network issues.
This commit is contained in:
Carlos Rafael Giani 2025-10-23 17:53:54 +02:00
parent 5d21e12658
commit 3e0f4daf60
1 changed files with 131 additions and 2 deletions
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133
src/modules/module-rtp-sap.c
View file

@ -248,6 +248,16 @@ struct node {
struct session *session;
};
struct igmp_recovery {
struct pw_timer timer;
int socket_fd;
struct sockaddr_storage mcast_addr;
socklen_t mcast_len;
uint32_t if_index;
bool is_ipv6;
uint32_t deadline;
};
struct impl {
struct pw_properties *props;
@ -285,6 +295,10 @@ struct impl {
struct spa_source *sap_source;
uint32_t cleanup_interval;
/* IGMP recovery (triggers when no SAP packets are
* received after the recovery deadline is reached) */
struct igmp_recovery igmp_recovery;
uint32_t max_sessions;
uint32_t n_sessions;
struct spa_list sessions;
@ -466,7 +480,7 @@ error:
}
static int make_recv_socket(struct sockaddr_storage *sa, socklen_t salen,
char *ifname)
char *ifname, struct igmp_recovery *igmp_recovery)
{
int af, fd, val, res;
struct ifreq req;
@ -536,6 +550,16 @@ static int make_recv_socket(struct sockaddr_storage *sa, socklen_t salen,
goto error;
}
/* Store multicast info for recovery */
igmp_recovery->socket_fd = fd;
igmp_recovery->mcast_addr = ba;
igmp_recovery->mcast_len = salen;
igmp_recovery->if_index = req.ifr_ifindex;
igmp_recovery->is_ipv6 = (af == AF_INET6);
pw_log_debug("stored %s multicast info: socket_fd=%d, "
"if_index=%d", igmp_recovery->is_ipv6 ?
"IPv6" : "IPv4", fd, req.ifr_ifindex);
if (bind(fd, (struct sockaddr*)&ba, salen) < 0) {
res = -errno;
pw_log_error("bind() failed: %m");
@ -944,6 +968,97 @@ static int send_sap(struct impl *impl, struct session *sess, bool bye)
return res;
}
static void on_igmp_recovery_timer_event(void *data)
{
struct impl *impl = data;
char addr[128];
int res = 0;
/* Only attempt recovery if we have a valid socket and multicast address */
if (impl->igmp_recovery.socket_fd < 0) {
pw_log_debug("no socket, skipping IGMP recovery");
goto finish;
}
pw_net_get_ip(&impl->igmp_recovery.mcast_addr, addr, sizeof(addr), NULL, NULL);
pw_log_info("IGMP recovery triggered for %s", addr);
/* Force IGMP membership refresh by leaving the group first, then rejoin */
if (impl->igmp_recovery.is_ipv6) {
struct ipv6_mreq mr6;
memset(&mr6, 0, sizeof(mr6));
mr6.ipv6mr_multiaddr = ((struct sockaddr_in6*)&impl->igmp_recovery.mcast_addr)->sin6_addr;
mr6.ipv6mr_interface = impl->igmp_recovery.if_index;
/* Leave the group first */
res = setsockopt(impl->igmp_recovery.socket_fd, IPPROTO_IPV6, IPV6_LEAVE_GROUP,
&mr6, sizeof(mr6));
if (SPA_LIKELY(res == 0)) {
pw_log_info("left IPv6 multicast group");
} else {
if (errno == EADDRNOTAVAIL) {
pw_log_info("attempted to leave IPv6 multicast group, but "
"membership was already silently dropped");
} else {
pw_log_warn("failed to leave IPv6 multicast group: %m");
}
}
res = setsockopt(impl->igmp_recovery.socket_fd, IPPROTO_IPV6, IPV6_JOIN_GROUP,
&mr6, sizeof(mr6));
if (res < 0) {
pw_log_warn("failed to re-join IPv6 multicast group: %m");
} else {
pw_log_info("re-joined IPv6 multicast group successfully");
}
} else {
struct ip_mreqn mr4;
memset(&mr4, 0, sizeof(mr4));
mr4.imr_multiaddr = ((struct sockaddr_in*)&impl->igmp_recovery.mcast_addr)->sin_addr;
mr4.imr_ifindex = impl->igmp_recovery.if_index;
/* Leave the group first */
res = setsockopt(impl->igmp_recovery.socket_fd, IPPROTO_IP, IP_DROP_MEMBERSHIP,
&mr4, sizeof(mr4));
if (SPA_LIKELY(res == 0)) {
pw_log_info("left IPv4 multicast group");
} else {
if (errno == EADDRNOTAVAIL) {
pw_log_info("attempted to leave IPv4 multicast group, but "
"membership was already silently dropped");
} else {
pw_log_warn("failed to leave IPv4 multicast group: %m");
}
}
res = setsockopt(impl->igmp_recovery.socket_fd, IPPROTO_IP, IP_ADD_MEMBERSHIP,
&mr4, sizeof(mr4));
if (res < 0) {
pw_log_warn("failed to re-join IPv4 multicast group: %m");
} else {
pw_log_info("re-joined IPv4 multicast group successfully");
}
}
finish:
/* If rejoining failed, try again in 1 second. This can happen
* for example when the network interface went down, and is not
* yet up and running again, and ENODEV is returned as a result.
* Otherwise, continue with the usual deadline. */
pw_timer_queue_add(impl->timer_queue, &impl->igmp_recovery.timer,
&impl->igmp_recovery.timer.timeout,
((res == 0) ? impl->igmp_recovery.deadline : 1) * SPA_NSEC_PER_SEC,
on_igmp_recovery_timer_event, impl);
}
static void rearm_igmp_recovery_timer(struct impl *impl)
{
pw_timer_queue_cancel(&impl->igmp_recovery.timer);
pw_timer_queue_add(impl->timer_queue, &impl->igmp_recovery.timer,
NULL, impl->igmp_recovery.deadline * SPA_NSEC_PER_SEC,
on_igmp_recovery_timer_event, impl);
}
static void on_sap_send_timer_event(void *data)
{
struct impl *impl = data;
@ -1675,6 +1790,8 @@ on_sap_io(void *data, int fd, uint32_t mask)
buffer[len] = 0;
if ((res = parse_sap(impl, buffer, len)) < 0)
pw_log_warn("error parsing SAP: %s", spa_strerror(res));
rearm_igmp_recovery_timer(impl);
}
}
@ -1696,7 +1813,8 @@ static int start_sap(struct impl *impl)
pw_log_error("can't add SAP send timer: %s", spa_strerror(res));
goto error;
}
if ((fd = make_recv_socket(&impl->sap_addr, impl->sap_len, impl->ifname)) < 0) {
if ((fd = make_recv_socket(&impl->sap_addr, impl->sap_len, impl->ifname,
&(impl->igmp_recovery))) < 0) {
/* If make_recv_socket() tries to create a socket and join to a multicast
* group while the network interfaces are not ready yet to do so
* (usually because a network manager component is still setting up
@ -1746,6 +1864,8 @@ static int start_sap(struct impl *impl)
goto error;
}
rearm_igmp_recovery_timer(impl);
finish:
return res;
@ -1884,6 +2004,7 @@ static void impl_destroy(struct impl *impl)
pw_timer_queue_cancel(&impl->sap_send_timer);
pw_timer_queue_cancel(&impl->start_sap_retry_timer);
pw_timer_queue_cancel(&impl->igmp_recovery.timer);
if (impl->sap_source)
pw_loop_destroy_source(impl->loop, impl->sap_source);
@ -1950,6 +2071,9 @@ int pipewire__module_init(struct pw_impl_module *module, const char *args)
impl->ptp_fd = -1;
spa_list_init(&impl->sessions);
impl->igmp_recovery.socket_fd = -1;
impl->igmp_recovery.if_index = -1;
if (args == NULL)
args = "";
@ -1985,6 +2109,11 @@ int pipewire__module_init(struct pw_impl_module *module, const char *args)
impl->cleanup_interval = pw_properties_get_uint32(impl->props,
"sap.cleanup.sec", DEFAULT_CLEANUP_SEC);
/* We will use half of the cleanup interval for IGMP deadline, minimum 1 second */
impl->igmp_recovery.deadline = SPA_MAX(impl->cleanup_interval / 2, 1u);
pw_log_info("using IGMP deadline of %" PRIu32 " second(s)",
impl->igmp_recovery.deadline);
impl->ttl = pw_properties_get_uint32(props, "net.ttl", DEFAULT_TTL);
impl->mcast_loop = pw_properties_get_bool(props, "net.loop", DEFAULT_LOOP);
impl->max_sessions = pw_properties_get_uint32(props, "sap.max-sessions", DEFAULT_MAX_SESSIONS);