netlink: clean up sockets, close files

Sockets are handled for most usage paths, except for shutdown. Handle
those at shutdown.

(cherry picked from commit 3cbbea8)
Signed-off-by: Paul Donald <newtwen+github@gmail.com>
Link: openwrt#367
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

Author: systemcrash

src/netlink.c

@@ -53,6 +53,29 @@ static struct event_socket rtnl_event = {
 	.sock_bufsize = 133120,
 };
 
+/* Shut down and free netlink sockets/registration. Safe to call multiple times. */
+static void netlink_shutdown(void)
+{
+	/* Deregister event and free the event socket */
+	if (rtnl_event.sock) {
+		odhcpd_deregister(&rtnl_event.ev);
+
+		if (rtnl_event.ev.uloop.fd >= 0) {
+			close(rtnl_event.ev.uloop.fd);
+			rtnl_event.ev.uloop.fd = -1;
+		}
+
+		nl_socket_free(rtnl_event.sock);
+		rtnl_event.sock = NULL;
+	}
+
+	/* Free the primary rtnl socket */
+	if (rtnl_socket) {
+		nl_socket_free(rtnl_socket);
+		rtnl_socket = NULL;
+	}
+}
+
 int netlink_init(void)
 {
 	rtnl_socket = create_socket(NETLINK_ROUTE);
@@ -85,19 +108,12 @@ int netlink_init(void)
 
 	odhcpd_register(&rtnl_event.ev);
 
+	atexit(netlink_shutdown);
+
 	return 0;
 
 err:
-	if (rtnl_socket) {
-		nl_socket_free(rtnl_socket);
-		rtnl_socket = NULL;
-	}
-
-	if (rtnl_event.sock) {
-		nl_socket_free(rtnl_event.sock);
-		rtnl_event.sock = NULL;
-		rtnl_event.ev.uloop.fd = -1;
-	}
+	netlink_shutdown();
 
 	return -1;
 }

src/router.c

@@ -45,6 +45,15 @@ static FILE *fp_route = NULL;
 
 #define TIME_LEFT(t1, now) ((t1) != UINT32_MAX ? (t1) - (now) : UINT32_MAX)
 
+/* Shutdown helper: close fp_route if open. Safe to call multiple times. */
+static void router_shutdown(void)
+{
+	if (fp_route) {
+		fclose(fp_route);
+		fp_route = NULL;
+	}
+}
+
 int router_init(void)
 {
 	int ret = 0;
@@ -60,11 +69,11 @@ int router_init(void)
 		ret = -1;
 	}
 
+	atexit(router_shutdown);
+
 out:
-	if (ret < 0 && fp_route) {
-		fclose(fp_route);
-		fp_route = NULL;
-	}
+	if (ret < 0)
+		router_shutdown();
 
 	return ret;
 }