+ *full_hostname = h;
+ h = NULL;
+
+ return 0;
+}
+
+static const char *fallback_hostname(void) {
+
+ /* Determine the fall back hostname. For exposing this system to the outside world, we cannot have it to be
+ * "localhost" even if that's the compiled in hostname. In this case, let's revert to "linux" instead. */
+
+ if (is_localhost(FALLBACK_HOSTNAME))
+ return "linux";
+
+ return FALLBACK_HOSTNAME;
+}
+
+static int make_fallback_hostnames(char **full_hostname, char **llmnr_hostname, char **mdns_hostname) {
+ _cleanup_free_ char *n = NULL, *m = NULL;
+ char label[DNS_LABEL_MAX], *h;
+ const char *p;
+ int r;
+
+ assert(full_hostname);
+ assert(llmnr_hostname);
+ assert(mdns_hostname);
+
+ p = fallback_hostname();
+ r = dns_label_unescape(&p, label, sizeof(label));
+ if (r < 0)
+ return log_error_errno(r, "Failed to unescape fallback host name: %m");
+
+ assert(r > 0); /* The fallback hostname must have at least one label */
+
+ r = dns_label_escape_new(label, r, &n);
+ if (r < 0)
+ return log_error_errno(r, "Failed to escape fallback hostname: %m");
+
+ r = dns_name_concat(n, "local", &m);
+ if (r < 0)
+ return log_error_errno(r, "Failed to concatenate mDNS hostname: %m");
+
+ h = strdup(fallback_hostname());
+ if (!h)
+ return log_oom();
+
+ *llmnr_hostname = n;
+ n = NULL;
+
+ *mdns_hostname = m;
+ m = NULL;
+
+ *full_hostname = h;
+