ipv6: special-case fe80::1

It's expected for binding that fe80::1 maps to lo, but in fact there is no
such address typically bound to any interface explicitly.

This patch handles it as a special case on ipv6 enabled builds forcibly
mapping it to lo as expected.

#3028

Author: lws-team

.gitignore

@@ -64,3 +64,4 @@ doc
 /destdir/
 /bb1/
 /bb3/
+/bin/

lib/roles/http/server/server.c

@@ -86,7 +86,8 @@ _lws_vhost_init_server_af(struct vh_sock_args *a)
 {
 	struct lws_context *cx = a->vhost->context;
 	struct lws_context_per_thread *pt;
-	int n, opt = 1, limit = 1;
+	int n, opt = 1, limit = 1, san = 2;
+	const char *_iface = a->vhost->iface;
 	lws_sockfd_type sockfd;
 	struct lws *wsi;
 	int m = 0, is;
@@ -97,21 +98,32 @@ _lws_vhost_init_server_af(struct vh_sock_args *a)
 	(void)method_names;
 	(void)opt;
 
+#ifdef LWS_WITH_IPV6
+        if (LWS_IPV6_ENABLED(a->vhost)) {
+		if (_iface && !strcmp(_iface, "fe80::1"))
+			_iface = "lo";
+	}
+#endif
+
 	lwsl_info("%s: af %d\n", __func__, (int)a->af);
 
 	if (lws_vhost_foreach_listen_wsi(a->vhost->context, a, check_extant))
 		return 0;
 
 deal:
 
-	if (a->vhost->iface) {
+	if (!san--) {
+		return -1;
+	}
+
+	if (_iface) {
 
 		/*
 		 * let's check before we do anything else about the disposition
 		 * of the interface he wants to bind to...
 		 */
 		is = lws_socket_bind(a->vhost, NULL, LWS_SOCK_INVALID,
-				     a->vhost->listen_port, a->vhost->iface,
+				     a->vhost->listen_port, _iface,
 				     a->af);
 		lwsl_debug("initial if check says %d\n", is);
 
@@ -158,7 +170,7 @@ _lws_vhost_init_server_af(struct vh_sock_args *a)
 
 			/* first time */
 			lwsl_err("%s: VH %s: iface %s port %d DOESN'T EXIST\n",
-				 __func__, a->vhost->name, a->vhost->iface,
+				 __func__, a->vhost->name, _iface,
 				 a->vhost->listen_port);
 
 			return (a->info->options &
@@ -172,7 +184,7 @@ _lws_vhost_init_server_af(struct vh_sock_args *a)
 				return -1;
 
 			lwsl_err("%s: VH %s: iface %s port %d NOT USABLE\n",
-				 __func__, a->vhost->name, a->vhost->iface,
+				 __func__, a->vhost->name, _iface,
 				 a->vhost->listen_port);
 
 			return (a->info->options &
@@ -273,7 +285,7 @@ _lws_vhost_init_server_af(struct vh_sock_args *a)
 
 		is = lws_socket_bind(a->vhost, NULL, sockfd,
 				     a->vhost->listen_port,
-				     a->vhost->iface, a->af);
+				     _iface, a->af);
 
 		if (is == LWS_ITOSA_BUSY) {
 			/* treat as fatal */
@@ -288,9 +300,9 @@ _lws_vhost_init_server_af(struct vh_sock_args *a)
 		 * here despite we earlier confirmed it.
 		 */
 		if (is < 0) {
-			lwsl_info("%s: lws_socket_bind says %d\n", __func__, is);
+			lwsl_info("%s: A lws_socket_bind says %d\n", __func__, is);
 			compatible_close(sockfd);
-			if (a->vhost->iface)
+			if (_iface)
 				goto deal;
 			return -1;
 		}
@@ -316,7 +328,7 @@ _lws_vhost_init_server_af(struct vh_sock_args *a)
 			wsi->unix_skt = 1;
 			a->vhost->listen_port = is;
 
-			lwsl_debug("%s: lws_socket_bind says %d\n", __func__, is);
+			lwsl_debug("%s: B lws_socket_bind says %d\n", __func__, is);
 		}
 
 		wsi->desc.sockfd = sockfd;
@@ -375,19 +387,19 @@ _lws_vhost_init_server_af(struct vh_sock_args *a)
 				     &a->vhost->context->lcg[LWSLCG_WSI],
 				     &wsi->lc, "listen|%s|%s|%d",
 				     a->vhost->name,
-				     a->vhost->iface ? a->vhost->iface : "",
+				     _iface ? _iface : "",
 				     (int)a->vhost->listen_port);
 
 	} /* for each thread able to independently listen */
 
 	if (!lws_check_opt(cx->options, LWS_SERVER_OPTION_EXPLICIT_VHOSTS)) {
 #ifdef LWS_WITH_UNIX_SOCK
 		if (a->af == AF_UNIX)
-			lwsl_info(" Listening on \"%s\"\n", a->vhost->iface);
+			lwsl_info(" Listening on \"%s\"\n", _iface);
 		else
 #endif
 			lwsl_info(" Listening on %s:%d\n",
-					a->vhost->iface,
+					_iface,
 					a->vhost->listen_port);
         }