unixsocket: make socket connection fault tolerant

When the l2tpd is killed, the unix socket will permanently loose the connection,
even if l2tpd is restarted the connection is still blocked. This commit adds
some fault tolerance mechanisms to automatically reconnect the socket as soon
as it is available again.

1 files changed, 55 insertions, 13 deletions

diff --git a/src/input/unixsocket.c b/src/input/unixsocket.c
index 6a9e83b..7bf99c7 100644
--- a/src/input/unixsocket.c
+++ b/src/input/unixsocket.c
@@ -46,17 +46,33 @@ void *tall_unixsocket_ctx;
 
 struct unixsocket_line {
 	struct osmo_fd fd;
+	struct osmo_timer_list timer;
 };
 
+static int unixsocket_line_update(struct e1inp_line *line);
 static int ts_want_write(struct e1inp_ts *e1i_ts);
 
 static int unixsocket_exception_cb(struct osmo_fd *bfd)
 {
 	struct e1inp_line *line = bfd->data;
-	LOGP(DLINP, LOGL_ERROR, "unixsocket: closing socket. Exception cb called.\n");
 
+	LOGP(DLINP, LOGL_ERROR,
+	     "Socket connection failure, reconnecting... (line=%p, fd=%d)\n",
+	     line, bfd->fd);
+
+	/* Unregister faulty file descriptor from select loop */
+	if(osmo_fd_is_registered(bfd)) {
+		LOGP(DLINP, LOGL_DEBUG,
+		     "removing inactive socket from select loop... (line=%p, fd=%d)\n",
+		     line, bfd->fd);
+		osmo_fd_unregister(bfd);
+	}
+
+	/* Close faulty file descriptor */
 	close(bfd->fd);
 
+	unixsocket_line_update(line);
+
 	return 0;
 }
 
@@ -79,6 +95,9 @@ static int unixsocket_read_cb(struct osmo_fd *bfd)
 	}
 	msgb_put(msg, ret);
 
+	LOGP(DLMI, LOGL_DEBUG, "rx msg: %s (fd=%d)\n",
+	     osmo_hexdump_nospc(msg->data, msg->len), bfd->fd);
+
 	return e1inp_rx_ts_lapd(&line->ts[0], msg);
 }
 
@@ -103,7 +122,8 @@ static int unixsocket_write_cb(struct osmo_fd *bfd)
 	msg = e1inp_tx_ts(e1i_ts, &sign_link);
 	if (!msg) {
 		/* no message after tx delay timer */
-		LOGP(DLINP, LOGL_INFO, "unixsocket: no message available");
+		LOGP(DLINP, LOGL_INFO,
+		     "no message available (line=%p)\n", line);
 		return 0;
 	}
 
@@ -113,7 +133,8 @@ static int unixsocket_write_cb(struct osmo_fd *bfd)
 
 	osmo_timer_schedule(&e1i_ts->sign.tx_timer, 0, e1i_ts->sign.delay);
 
-	LOGP(DLINP, LOGL_INFO, "unixsocket: sending: %s", msgb_hexdump(msg));
+	LOGP(DLINP, LOGL_INFO, "sending: %s (line=%p)\n",
+	     msgb_hexdump(msg), line);
 	lapd_transmit(e1i_ts->lapd, sign_link->tei,
 			sign_link->sapi, msg);
 
@@ -151,6 +172,9 @@ static void unixsocket_write_msg(struct msgb *msg, void *cbdata)
 	struct osmo_fd *bfd = cbdata;
 	int ret;
 
+	LOGP(DLMI, LOGL_DEBUG, "tx msg: %s (fd=%d)\n",
+	     osmo_hexdump_nospc(msg->data, msg->len), bfd->fd);
+
 	ret = write(bfd->fd, msg->data, msg->len);
 	msgb_free(msg);
 	if (ret == -1)
@@ -178,38 +202,55 @@ static int unixsocket_line_update(struct e1inp_line *line)
 		line->driver_data = talloc_zero(line, struct unixsocket_line);
 
 	if (!line->driver_data) {
-		LOGP(DLINP, LOGL_ERROR, "unixsocket: OOM in line update\n");
+		LOGP(DLINP, LOGL_ERROR,
+		     "OOM in line update (line=%p)\n", line);
 		return -ENOMEM;
 	}
 
 	config = line->driver_data;
-
 	config->fd.data = line;
 	config->fd.when = BSC_FD_READ;
 	config->fd.cb = unixsocket_cb;
-	ret = osmo_sock_unix_init(SOCK_SEQPACKET, 0, sock_path, OSMO_SOCK_F_CONNECT);
 
+	/* Open unix domain socket */
+	ret = osmo_sock_unix_init(SOCK_SEQPACKET, 0, sock_path,
+				  OSMO_SOCK_F_CONNECT);
 	if (ret < 0) {
-		talloc_free(config);
+		/* Note: We will not free the allocated driver_data memory if
+		 * opening the socket fails. The caller may want to call this
+		 * function multiple times using config->fd.data as line
+		 * parameter. Freeing now would destroy that reference. */
+		LOGP(DLINP, LOGL_ERROR,
+		     "unable to open socket: %s (line=%p, fd=%d)\n", sock_path,
+		     line, config->fd.fd);
 		return ret;
 	}
-
+	LOGP(DLINP, LOGL_DEBUG,
+	     "successfully opend (new) socket: %s (line=%p, fd=%d, ret=%d)\n",
+	     sock_path, line, config->fd.fd, ret);
 	config->fd.fd = ret;
+
+	/* Register socket in select loop */
 	if (osmo_fd_register(&config->fd) < 0) {
+		LOGP(DLINP, LOGL_ERROR,
+		     "error registering new socket (line=%p, fd=%d)\n",
+		     line, config->fd.fd);
 		close(config->fd.fd);
 		return -EIO;
 	}
 
+	/* Set line parameter */
 	for (i = 0; i < ARRAY_SIZE(line->ts); i++) {
 		struct e1inp_ts *e1i_ts = &line->ts[i];
-
-		if (!e1i_ts->lapd)
+		if (!e1i_ts->lapd) {
 			e1i_ts->lapd = lapd_instance_alloc(1,
-				unixsocket_write_msg, &config->fd, e1inp_dlsap_up,
-				e1i_ts, &lapd_profile_abis);
+				unixsocket_write_msg, &config->fd,
+				e1inp_dlsap_up, e1i_ts, &lapd_profile_abis);
+		}
 	}
 
-	/* Ensure Superchannel is turned of when a new connection is made */
+	/* Ensure ericsson-superchannel is turned of when
+	 * a new connection is made */
 	e1inp_ericsson_set_altc(line, 0);
 
 	return ret;
@@ -256,3 +297,4 @@ void e1inp_ericsson_set_altc(struct e1inp_line *unixline, int superchannel)
 
 	unixsocket_write_msg(msg, &config->fd);
 }
+