mgcp-client: Add keepalive feature
The `keepalive` feature in libosmo-mgcp-client allows scheduling periodical
queries on the MGCP layer in order to make sure it is reachable and hence
obtain information on the state of the MGCP link.
This patch only uses it to print the status on the VTY, but it will be used
too in a follow-up commit by the MGW Pool when picking an MGW from the pool:
MGWs whose link is considered to be DOWN are skipped.
The feature consists of:
- A `keepalive request-interval` which will trigger a transmission of an MGCP
AuditEndpoint command targeting endpoint with name `keepalive request-endpoint`.
This interval is updated every time any message is transmitted in the MGCP
link, meaning the MGCP AuditEndpoint message is only triggered if no message
has been transmitted since `keepalive request-interval` seconds ago.
- A `keepalive timeout` considering the MGW to be non-reachable (link DOWN) if
no message is received over that amount of time.
The `keepalive` parameters are to be preferrably configured so that
"keepalive request-interval" * 2 < "keepalive timeout".
Example VTY configuration of `keepalive` feature in libosmo-mgcp-client:
----
mgw 0
...
keepalive request-interval 20 <1>
keepalive request-endpoint null <2>
keepalive timeout 50 <3>
----
<1> Transmit an MGCP AuditEndpoint message to the MGW if no message has been
sent to it over last 10 seconds
<2> The MGCP AuditEndpoint targets the `null` endpoint. This is a special
endpoint available at OsmoMGW for those purposes, but any available
endpoint can be configured and used instead.
<3> Consider the MGCP link to be DOWN if no message is received from the
MGW over the last 50 seconds
NOTE: The `keepalive` feature is disabled by default, and must be explicitly
configured in order to enable it.
Related: SYS#6481
Change-Id: I3dc74c78548d017f272da863d5282dc5e0020ca3
diff --git a/src/libosmo-mgcp-client/mgcp_client.c b/src/libosmo-mgcp-client/mgcp_client.c
index f74255c..677a4f3 100644
--- a/src/libosmo-mgcp-client/mgcp_client.c
+++ b/src/libosmo-mgcp-client/mgcp_client.c
@@ -202,6 +202,11 @@
.local_port = -1,
.remote_addr = NULL,
.remote_port = -1,
+ .keepalive = {
+ .timeout_sec = 0, /* disabled */
+ .req_interval_sec = 0, /* disabled */
+ .req_endpoint_name = MGCP_CLIENT_KEEPALIVE_DEFAULT_ENDP,
+ },
};
INIT_LLIST_HEAD(&conf->reset_epnames);
@@ -696,6 +701,14 @@
r = talloc_zero(mgcp, struct mgcp_response);
OSMO_ASSERT(r);
+ /* Re-arm keepalive timer if enabled */
+ if (OSMO_UNLIKELY(mgcp->conn_up == false)) {
+ LOGPMGW(mgcp, LOGL_NOTICE, "MGCP link to MGW now considered UP\n");
+ mgcp->conn_up = true;
+ }
+ if (mgcp->actual.keepalive.timeout_sec > 0)
+ osmo_timer_schedule(&mgcp->keepalive_rx_timer, mgcp->actual.keepalive.timeout_sec, 0);
+
rc = mgcp_response_parse_head(r, msg);
if (rc) {
LOGPMGW(mgcp, LOGL_ERROR, "Cannot parse MGCP response (head)\n");
@@ -766,10 +779,14 @@
osmo_escape_str((const char *)msg->data, OSMO_MIN(42, msg->len)));
ret = write(fd->fd, msg->data, msg->len);
- if (ret != msg->len)
+ if (OSMO_UNLIKELY(ret != msg->len))
LOGPMGW(mgcp, LOGL_ERROR, "Failed to Tx MGCP: %s: %d='%s'; msg: len=%u '%s'...\n",
osmo_sock_get_name2(fd->fd), errno, strerror(errno),
msg->len, osmo_escape_str((const char *)msg->data, OSMO_MIN(42, msg->len)));
+
+ /* Re-arm the keepalive Tx timer: */
+ if (mgcp->actual.keepalive.req_interval_sec > 0)
+ osmo_timer_schedule(&mgcp->keepalive_tx_timer, mgcp->actual.keepalive.req_interval_sec, 0);
return ret;
}
@@ -807,6 +824,39 @@
mgcp_client_tx(mgcp, msgb_dlcx, &_ignore_mgcp_response, NULL);
}
+/* Format AuditEndpoint message (fire and forget) and send it off to the MGW */
+static void _mgcp_client_send_auep(struct mgcp_client *mgcp, const char *epname)
+{
+ struct msgb *msgb_auep;
+ struct mgcp_msg mgcp_msg_auep = {
+ .verb = MGCP_VERB_AUEP,
+ .presence = MGCP_MSG_PRESENCE_ENDPOINT,
+ };
+ OSMO_STRLCPY_ARRAY(mgcp_msg_auep.endpoint, epname);
+ msgb_auep = mgcp_msg_gen(mgcp, &mgcp_msg_auep);
+ mgcp_client_tx(mgcp, msgb_auep, &_ignore_mgcp_response, NULL);
+}
+
+static void mgcp_client_keepalive_tx_timer_cb(void *data)
+{
+ struct mgcp_client *mgcp = (struct mgcp_client *)data;
+ LOGPMGW(mgcp, LOGL_INFO, "Triggering keepalive MGCP request\n");
+ const char *epname = _mgcp_client_name_append_domain(mgcp, mgcp->actual.keepalive.req_endpoint_name);
+ _mgcp_client_send_auep(mgcp, epname);
+
+ /* Re-arm the timer: */
+ osmo_timer_schedule(&mgcp->keepalive_tx_timer, mgcp->actual.keepalive.req_interval_sec, 0);
+}
+
+static void mgcp_client_keepalive_rx_timer_cb(void *data)
+{
+ struct mgcp_client *mgcp = (struct mgcp_client *)data;
+ LOGPMGW(mgcp, LOGL_ERROR, "MGCP link to MGW now considered DOWN (keepalive timeout, more than %u seconds with no answer from MGW)\n",
+ mgcp->actual.keepalive.timeout_sec);
+ mgcp->conn_up = false;
+ /* TODO: Potentially time out all ongoing transactions for that MGW. Maybe based on VTY cfg? */
+}
+
struct mgcp_client *mgcp_client_init(void *ctx,
struct mgcp_client_conf *conf)
{
@@ -851,6 +901,15 @@
if (conf->description)
mgcp->actual.description = talloc_strdup(mgcp, conf->description);
+ osmo_wqueue_init(&mgcp->wq, 1024);
+ mgcp->wq.read_cb = mgcp_do_read;
+ mgcp->wq.write_cb = mgcp_do_write;
+ osmo_fd_setup(&mgcp->wq.bfd, -1, OSMO_FD_READ, osmo_wqueue_bfd_cb, mgcp, 0);
+
+ memcpy(&mgcp->actual.keepalive, &conf->keepalive, sizeof(conf->keepalive));
+ osmo_timer_setup(&mgcp->keepalive_tx_timer, mgcp_client_keepalive_tx_timer_cb, mgcp);
+ osmo_timer_setup(&mgcp->keepalive_rx_timer, mgcp_client_keepalive_rx_timer_cb, mgcp);
+
return mgcp;
}
@@ -859,24 +918,17 @@
* \returns 0 on success, -EINVAL on error. */
int mgcp_client_connect(struct mgcp_client *mgcp)
{
- struct osmo_wqueue *wq;
int rc;
struct reset_ep *reset_ep;
const char *epname;
+ bool some_dlcx_sent = false;
if (!mgcp) {
LOGPMGW(mgcp, LOGL_FATAL, "Client not initialized properly\n");
return -EINVAL;
}
- wq = &mgcp->wq;
- osmo_wqueue_init(wq, 1024);
- wq->read_cb = mgcp_do_read;
- wq->write_cb = mgcp_do_write;
-
- osmo_fd_setup(&wq->bfd, -1, OSMO_FD_READ, osmo_wqueue_bfd_cb, mgcp, 0);
-
- rc = osmo_sock_init2_ofd(&wq->bfd, AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, mgcp->actual.local_addr,
+ rc = osmo_sock_init2_ofd(&mgcp->wq.bfd, AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, mgcp->actual.local_addr,
mgcp->actual.local_port, mgcp->actual.remote_addr, mgcp->actual.remote_port,
OSMO_SOCK_F_BIND | OSMO_SOCK_F_CONNECT);
if (rc < 0) {
@@ -888,7 +940,7 @@
goto error_close_fd;
}
- LOGPMGW(mgcp, LOGL_INFO, "MGW connection: %s\n", osmo_sock_get_name2(wq->bfd.fd));
+ LOGPMGW(mgcp, LOGL_INFO, "MGW connection: %s\n", osmo_sock_get_name2(mgcp->wq.bfd.fd));
/* If configured, send a DLCX message to the endpoints that are configured to
* be reset on startup. Usually this is a wildcarded endpoint. */
@@ -896,11 +948,27 @@
epname = _mgcp_client_name_append_domain(mgcp, reset_ep->name);
LOGPMGW(mgcp, LOGL_INFO, "Sending DLCX to: %s\n", epname);
_mgcp_client_send_dlcx(mgcp, epname);
+ some_dlcx_sent = true;
}
+
+ if (!some_dlcx_sent) {
+ if (mgcp->actual.keepalive.req_interval_sec > 0) {
+ /* Attempt an immediate probe to find out if link is UP or DOWN: */
+ osmo_timer_schedule(&mgcp->keepalive_tx_timer, 0, 0);
+ } else {
+ /* Assume link is UP by default, so that this MGW can be selected: */
+ mgcp->conn_up = true;
+ }
+ }
+ /* else: keepalive_tx_timer was already scheduled (if needed) down in the stack during Tx DLCX above */
+
+ if (mgcp->actual.keepalive.timeout_sec > 0)
+ osmo_timer_schedule(&mgcp->keepalive_rx_timer, mgcp->actual.keepalive.timeout_sec, 0);
+
return 0;
error_close_fd:
- close(wq->bfd.fd);
- wq->bfd.fd = -1;
+ close(mgcp->wq.bfd.fd);
+ mgcp->wq.bfd.fd = -1;
return rc;
}
@@ -924,6 +992,11 @@
return;
}
+ /* Disarm keepalive Tx/Rx timer until next connect() */
+ osmo_timer_del(&mgcp->keepalive_rx_timer);
+ osmo_timer_del(&mgcp->keepalive_tx_timer);
+ mgcp->conn_up = false;
+
wq = &mgcp->wq;
osmo_wqueue_clear(wq);
LOGPMGW(mgcp, LOGL_INFO, "MGCP association: %s -- closed!\n", osmo_sock_get_name2(wq->bfd.fd));