--- get_host_realm.c.orig	2007-03-24 17:25:09.000000000 -0400
+++ get_host_realm.c	2007-03-24 17:25:48.000000000 -0400
@@ -210,6 +210,78 @@
     return KRB5_ERR_HOST_REALM_UNKNOWN;
 }
 
+static int
+dns_get_default_fqdn(unsigned char *dst, size_t dn)
+{
+	unsigned char buf[HOST_NAME_MAX];
+	unsigned char *name = buf, *dot, *dlim = dst + dn;
+
+	if (dst == NULL || dn < 1) {
+		errno = EINVAL;
+		return -1;
+	}
+	dlim--; /* ensure room for zero term */
+
+	if (gethostname(buf, sizeof(buf)) == -1) {
+		return -1;
+	}
+
+	dot = strchr(name, '.');
+	if (dot == NULL || dot[1] == '\0') {
+		/* If name doesn't have components (trailing dot doesn't
+		 * count), then try harder
+		 */
+		struct hostent *he;
+
+		he = gethostbyname(buf);
+		if (he == NULL) {
+			return -1;
+		}
+		name = he->h_name;
+
+		dot = strchr(name, '.');
+		if (dot == NULL || dot[1] == '\0') {
+			/* Still no components, try harder still
+			 */
+			int ai;
+
+			name = NULL;
+			for (ai = 0; he->h_aliases[ai]; ai++) {
+				name = he->h_aliases[ai];
+
+				dot = strchr(name, '.');
+				if (dot && dot[1] != '\0') {
+					break; /* Found a name with components */
+				}
+				name = NULL;
+			}
+		}
+	}
+
+	if (name == NULL) {
+		errno = ENOENT;
+		return -1;
+	}
+
+	/* If we make it here, we have a name with components. Copy
+	 * everything except a trailing dot into dst.
+	 */
+	dot = NULL;
+	while (*name) {
+		if (dst == dlim) {
+			errno = ENOBUFS;
+			return -1;
+		}
+		if (*name == '.')
+			dot = dst;
+		*dst++ = *name++;
+	}
+	if (name[-1] == '.')
+		dst = dot;
+	*dst = '\0';
+
+	return 0;
+}
 /*
  * Return the realm(s) of `host' as a NULL-terminated list in
  * `realms'. Free `realms' with krb5_free_host_realm().
@@ -226,7 +298,7 @@
     int use_dns;
 
     if (host == NULL) {
-	if (gethostname (hostname, sizeof(hostname))) {
+	if (dns_get_default_fqdn(hostname, sizeof(hostname))) {
 	    *realms = NULL;
 	    return errno;
 	}