core: merge branch 'th/bgo738590_dhcp_server_route' (bgo #738590)

https://bugzilla.gnome.org/show_bug.cgi?id=738590

Signed-off-by: Thomas Haller <thaller@redhat.com>

src/NetworkManagerUtils.c

@@ -120,15 +120,15 @@ nm_utils_ip4_address_clear_host_address (in_addr_t addr, guint8 plen)
  * @src: source ip6 address
  * @plen: prefix length of network
  *
- * Note: this function is self assignment save, to update @src inplace, set both
+ * Note: this function is self assignment safe, to update @src inplace, set both
  * @dst and @src to the same destination.
  */
-void
+const struct in6_addr *
 nm_utils_ip6_address_clear_host_address (struct in6_addr *dst, const struct in6_addr *src, guint8 plen)
 {
-	g_return_if_fail (plen <= 128);
-	g_return_if_fail (src);
-	g_return_if_fail (dst);
+	g_return_val_if_fail (plen <= 128, NULL);
+	g_return_val_if_fail (src, NULL);
+	g_return_val_if_fail (dst, NULL);
 
 	if (plen < 128) {
 		guint nbytes = plen / 8;
@@ -144,6 +144,8 @@ nm_utils_ip6_address_clear_host_address (struct in6_addr *dst, const struct in6_
 			memset (&dst->s6_addr[nbytes], 0, 16 - nbytes);
 	} else if (src != dst)
 		*dst = *src;
+
+	return dst;
 }
 
 

src/NetworkManagerUtils.h

@@ -31,7 +31,22 @@
 gboolean nm_ethernet_address_is_valid (gconstpointer addr, gssize len);
 
 in_addr_t nm_utils_ip4_address_clear_host_address (in_addr_t addr, guint8 plen);
-void nm_utils_ip6_address_clear_host_address (struct in6_addr *dst, const struct in6_addr *src, guint8 plen);
+const struct in6_addr *nm_utils_ip6_address_clear_host_address (struct in6_addr *dst, const struct in6_addr *src, guint8 plen);
+
+/**
+ * nm_utils_ip6_route_metric_normalize:
+ * @metric: the route metric
+ *
+ * For IPv6 route, kernel treats the value 0 as IP6_RT_PRIO_USER (1024).
+ * Thus, when comparing metric (values), we want to treat zero as NM_PLATFORM_ROUTE_METRIC_DEFAULT.
+ *
+ * Returns: @metric, if @metric is not zero, otherwise 1024.
+ */
+static inline guint32
+nm_utils_ip6_route_metric_normalize (guint32 metric)
+{
+	return metric ? metric : 1024 /*NM_PLATFORM_ROUTE_METRIC_DEFAULT*/;
+}
 
 int nm_spawn_process (const char *args);
 

src/dhcp-manager/nm-dhcp-utils.c

@@ -451,13 +451,13 @@ nm_dhcp_utils_ip4_config_from_options (const char *iface,
 	str = g_hash_table_lookup (options, "dhcp_server_identifier");
 	if (str) {
 		if (inet_pton (AF_INET, str, &tmp_addr) > 0) {
-			NMPlatformIP4Route route;
-			guint32 mask = nm_utils_ip4_prefix_to_netmask (address.plen);
 
 			nm_log_info (LOGD_DHCP4, "  server identifier %s", str);
-			if ((tmp_addr & mask) != (address.address & mask)) {
-				/* DHCP server not on assigned subnet, route needed */
-				memset (&route, 0, sizeof (route));
+			if (   nm_utils_ip4_address_clear_host_address(tmp_addr, address.plen) != nm_utils_ip4_address_clear_host_address(address.address, address.plen)
+			    && !nm_ip4_config_get_direct_route_for_host (ip4_config, tmp_addr)) {
+				/* DHCP server not on assigned subnet and the no direct route was returned. Add route */
+				NMPlatformIP4Route route = { 0 };
+
 				route.network = tmp_addr;
 				route.plen = 32;
 				/* this will be a device route if gwaddr is 0 */

src/nm-ip4-config.c

@@ -1191,6 +1191,36 @@ nm_ip4_config_get_route (const NMIP4Config *config, guint i)
 	return &g_array_index (priv->routes, NMPlatformIP4Route, i);
 }
 
+const NMPlatformIP4Route *
+nm_ip4_config_get_direct_route_for_host (const NMIP4Config *config, guint32 host)
+{
+	NMIP4ConfigPrivate *priv = NM_IP4_CONFIG_GET_PRIVATE (config);
+	int i;
+	NMPlatformIP4Route *best_route = NULL;
+
+	g_return_val_if_fail (host, NULL);
+
+	for (i = 0; i < priv->routes->len; i++ ) {
+		NMPlatformIP4Route *item = &g_array_index (priv->routes, NMPlatformIP4Route, i);
+
+		if (item->gateway != 0)
+			continue;
+
+		if (best_route && best_route->plen > item->plen)
+			continue;
+
+		if (nm_utils_ip4_address_clear_host_address (host, item->plen) != nm_utils_ip4_address_clear_host_address (item->network, item->plen))
+			continue;
+
+		if (best_route && best_route->metric <= item->metric)
+			continue;
+
+		best_route = item;
+	}
+
+	return best_route;
+}
+
 /******************************************************************/
 
 void

src/nm-ip4-config.h

@@ -92,6 +92,8 @@ void nm_ip4_config_del_route (NMIP4Config *config, guint i);
 guint32 nm_ip4_config_get_num_routes (const NMIP4Config *config);
 const NMPlatformIP4Route *nm_ip4_config_get_route (const NMIP4Config *config, guint32 i);
 
+const NMPlatformIP4Route *nm_ip4_config_get_direct_route_for_host (const NMIP4Config *config, guint32 host);
+
 /* Nameservers */
 void nm_ip4_config_reset_nameservers (NMIP4Config *config);
 void nm_ip4_config_add_nameserver (NMIP4Config *config, guint32 nameserver);

src/nm-ip6-config.c

@@ -1196,6 +1196,41 @@ nm_ip6_config_get_route (const NMIP6Config *config, guint i)
 	return &g_array_index (priv->routes, NMPlatformIP6Route, i);
 }
 
+const NMPlatformIP6Route *
+nm_ip6_config_get_direct_route_for_host (const NMIP6Config *config, const struct in6_addr *host)
+{
+	NMIP6ConfigPrivate *priv = NM_IP6_CONFIG_GET_PRIVATE (config);
+	int i;
+	struct in6_addr network2, host2;
+	NMPlatformIP6Route *best_route = NULL;
+
+	g_return_val_if_fail (host && !IN6_IS_ADDR_UNSPECIFIED (host), NULL);
+
+	for (i = 0; i < priv->routes->len; i++ ) {
+		NMPlatformIP6Route *item = &g_array_index (priv->routes, NMPlatformIP6Route, i);
+
+		if (!IN6_IS_ADDR_UNSPECIFIED (&item->gateway))
+			continue;
+
+		if (best_route && best_route->plen > item->plen)
+			continue;
+
+		nm_utils_ip6_address_clear_host_address (&host2, host, item->plen);
+		nm_utils_ip6_address_clear_host_address (&network2, &item->network, item->plen);
+
+		if (!IN6_ARE_ADDR_EQUAL (&network2, &host2))
+			continue;
+
+		if (best_route &&
+		    nm_utils_ip6_route_metric_normalize (best_route->metric) <= nm_utils_ip6_route_metric_normalize (item->metric))
+			continue;
+
+		best_route = item;
+	}
+
+	return best_route;
+}
+
 /******************************************************************/
 
 void

src/nm-ip6-config.h

@@ -93,6 +93,8 @@ void nm_ip6_config_del_route (NMIP6Config *config, guint i);
 guint32 nm_ip6_config_get_num_routes (const NMIP6Config *config);
 const NMPlatformIP6Route *nm_ip6_config_get_route (const NMIP6Config *config, guint32 i);
 
+const NMPlatformIP6Route *nm_ip6_config_get_direct_route_for_host (const NMIP6Config *config, const struct in6_addr *host);
+
 /* Nameservers */
 void nm_ip6_config_reset_nameservers (NMIP6Config *config);
 void nm_ip6_config_add_nameserver (NMIP6Config *config, const struct in6_addr *nameserver);

src/platform/nm-platform.h

@@ -216,6 +216,8 @@ G_STATIC_ASSERT (G_STRUCT_OFFSET (NMPlatformIPAddress, address_ptr) == G_STRUCT_
 #undef __NMPlatformIPAddress_COMMON
 
 
+/* Adding an IPv6 route with metric 0, kernel translates to IP6_RT_PRIO_USER (1024).
+ * Thus, the value is not choosen arbitraily, but matches kernel IPv6 default. */
 #define NM_PLATFORM_ROUTE_METRIC_DEFAULT 1024
 
 #define __NMPlatformIPRoute_COMMON \