+#ifdef HAVE_GETNAMEINFO
+static char *
+smn_get_hostname(const struct sockaddr *sap, const socklen_t salen,
+ const char *name)
+{
+ char buf[NI_MAXHOST];
+ int error;
+
+ error = getnameinfo(sap, salen, buf, sizeof(buf), NULL, 0, NI_NAMEREQD);
+ if (error != 0) {
+ xlog(L_ERROR, "my_name '%s' is unusable: %s",
+ name, gai_strerror(error));
+ return NULL;
+ }
+ return strdup(buf);
+}
+#else /* !HAVE_GETNAMEINFO */
+static char *
+smn_get_hostname(const struct sockaddr *sap,
+ __attribute__ ((unused)) const socklen_t salen,
+ const char *name)
+{
+ const struct sockaddr_in *sin = (const struct sockaddr_in *)(char *)sap;
+ const struct in_addr *addr = &sin->sin_addr;
+ struct hostent *hp;
+
+ if (sap->sa_family != AF_INET) {
+ xlog(L_ERROR, "my_name '%s' is unusable: Bad address family",
+ name);
+ return NULL;
+ }
+
+ hp = gethostbyaddr(addr, (socklen_t)sizeof(addr), AF_INET);
+ if (hp == NULL) {
+ xlog(L_ERROR, "my_name '%s' is unusable: %s",
+ name, hstrerror(h_errno));
+ return NULL;
+ }
+ return strdup(hp->h_name);
+}
+#endif /* !HAVE_GETNAMEINFO */
+
+/*
+ * Presentation addresses are converted to their canonical hostnames.
+ * If the IP address does not map to a hostname, it is an error:
+ * we never send a presentation address as the argument of SM_NOTIFY.
+ *
+ * If "name" is not a presentation address, it is left alone. This
+ * allows the administrator some flexibility if DNS isn't configured
+ * exactly how sm-notify prefers it.
+ *
+ * Returns NUL-terminated C string containing the result, or NULL
+ * if the canonical name doesn't exist or cannot be determined.
+ * The caller must free the result with free(3).
+ */
+__attribute_malloc__
+static char *
+smn_verify_my_name(const char *name)
+{
+ struct addrinfo *ai = NULL;
+ struct addrinfo hint = {
+#ifdef IPV6_SUPPORTED
+ .ai_family = AF_UNSPEC,
+#else /* !IPV6_SUPPORTED */
+ .ai_family = AF_INET,
+#endif /* !IPV6_SUPPORTED */
+ .ai_flags = AI_NUMERICHOST,
+ };
+ char *retval;
+ int error;
+
+ error = getaddrinfo(name, NULL, &hint, &ai);
+ switch (error) {
+ case 0:
+ /* @name was a presentation address */
+ retval = smn_get_hostname(ai->ai_addr, ai->ai_addrlen, name);
+ freeaddrinfo(ai);
+ if (retval == NULL)
+ return NULL;
+ break;
+ case EAI_NONAME:
+ /* @name was not a presentation address */
+ retval = strdup(name);
+ break;
+ default:
+ xlog(L_ERROR, "my_name '%s' is unusable: %s",
+ name, gai_strerror(error));
+ return NULL;
+ }
+
+ xlog(D_GENERAL, "Canonical name for my_name '%s': %s",
+ name, retval);
+ return retval;
+}
+