+static int link_get_flags(unsigned index, unsigned *flags) {
+ _cleanup_free_ char *s = NULL, *p = NULL;
+ int r;
+
+ assert(index);
+ assert(flags);
+
+ if (asprintf(&p, "/run/systemd/network/links/%u", index) < 0)
+ return -ENOMEM;
+
+ r = parse_env_file(p, NEWLINE, "FLAGS", &s, NULL);
+ if (r == -ENOENT)
+ return -ENODATA;
+ else if (r < 0)
+ return r;
+ else if (!s)
+ return -EIO;
+
+ return safe_atou(s, flags);
+}
+
+_public_ int sd_network_link_is_loopback(unsigned index) {
+ unsigned flags;
+ int r;
+
+ r = link_get_flags(index, &flags);
+ if (r < 0)
+ return 0;
+
+ return flags & IFF_LOOPBACK;
+}
+