daemon: rework a bit systemd support

Use connect() as done by other implementations, notably the one in
sd_notify(2). Also add a check on socket length.

diff --git a/src/daemon/lldpd.c b/src/daemon/lldpd.c
index 918f31387301eac711a1cb462778c7f5ccd676b8..5486475336e69b995ea7958128f4c3a9e7d6b453 100644 (file)
--- a/src/daemon/lldpd.c
+++ b/src/daemon/lldpd.c
@@ -1459,36 +1459,44 @@ lldpd_started_by_systemd()
 {
 #  ifdef HOST_OS_LINUX
        int fd = -1;
+       int ret = 0;
+       size_t path_length;
+       struct sockaddr_un sun = {
+               .sun_family = AF_UNIX,
+       };
        const char *notifysocket = getenv("NOTIFY_SOCKET");
-       if (!notifysocket || !strchr("@/", notifysocket[0]) || strlen(notifysocket) < 2)
-               return 0;
+       if (!notifysocket || !strchr("@/", notifysocket[0]) ||
+           (path_length = strlen(notifysocket)) < 2)
+               goto done;
+
+       if (path_length >= sizeof(sun.sun_path)) {
+               log_warnx("main", "systemd notification socket is too long");
+               goto done;
+       }
+       strlcpy(sun.sun_path, notifysocket, sizeof(sun.sun_path));
+       if (notifysocket[0] == '@') sun.sun_path[0] = 0;
 
        log_debug("main", "running with systemd, don't fork but signal ready");
        if ((fd = socket(AF_UNIX, SOCK_DGRAM, 0)) < 0) {
                log_warn("main", "unable to open systemd notification socket %s",
                    notifysocket);
-               return 0;
+               goto done;
+       }
+       if (connect(fd, &sun, sizeof(sun)) != 0) {
+               log_warn("main", "unable to connect to systemd notification socket");
+               goto done;
        }
-
-       struct sockaddr_un su = { .sun_family = AF_UNIX };
-       strlcpy(su.sun_path, notifysocket, sizeof(su.sun_path));
-       if (notifysocket[0] == '@') su.sun_path[0] = 0;
-
        char ready[] = "READY=1";
-       struct iovec iov = { .iov_base = ready, .iov_len = sizeof ready - 1 };
-       struct msghdr hdr = { .msg_name = &su,
-               .msg_namelen =
-                   offsetof(struct sockaddr_un, sun_path) + strlen(notifysocket),
-               .msg_iov = &iov,
-               .msg_iovlen = 1 };
-       unsetenv("NOTIFY_SOCKET");
-       if (sendmsg(fd, &hdr, MSG_NOSIGNAL) < 0) {
+       ssize_t written = write(fd, ready, sizeof ready - 1);
+       if (written != (ssize_t)sizeof ready - 1) {
                log_warn("main", "unable to send notification to systemd");
-               close(fd);
-               return 0;
+               goto done;
        }
-       close(fd);
-       return 1;
+       unsetenv("NOTIFY_SOCKET");
+       ret = 1;
+done:
+       if (fd >= 0) close(fd);
+       return ret;
 #  else
        return 0;
 #  endif