platform: handle route table RT_TABLE_UNSPEC specially

Kernel does not allow to add a route with table 0 (RT_TABLE_UNSPEC). It
effectively is an alias for the main table. We must consider that when
comparing routes sementically.

3 files changed, 81 insertions, 18 deletions

diff --git a/src/platform/nm-linux-platform.c b/src/platform/nm-linux-platform.c
index 1edc2183bb..7245d16e77 100644
--- a/src/platform/nm-linux-platform.c
+++ b/src/platform/nm-linux-platform.c
@@ -2594,7 +2594,7 @@ _nl_msg_new_route (int nlmsg_type,
 	const NMPClass *klass = NMP_OBJECT_GET_CLASS (obj);
 	gboolean is_v4 = klass->addr_family == AF_INET;
 	const guint32 lock = ip_route_get_lock_flag (NMP_OBJECT_CAST_IP_ROUTE (obj));
-	const guint32 table = nm_platform_route_table_coerce (NMP_OBJECT_CAST_IP_ROUTE (obj)->table_coerced);
+	const guint32 table = nm_platform_route_table_uncoerce (NMP_OBJECT_CAST_IP_ROUTE (obj)->table_coerced, TRUE);
 	struct rtmsg rtmsg = {
 		.rtm_family = klass->addr_family,
 		.rtm_tos = is_v4
diff --git a/src/platform/nm-platform.c b/src/platform/nm-platform.c
index 686943a13f..b0cd3bc997 100644
--- a/src/platform/nm-platform.c
+++ b/src/platform/nm-platform.c
@@ -2904,7 +2904,7 @@ nm_platform_lookup_predicate_routes_main (const NMPObject *obj,
 {
 	nm_assert (NM_IN_SET (NMP_OBJECT_GET_TYPE (obj), NMP_OBJECT_TYPE_IP4_ROUTE,
 	                                                 NMP_OBJECT_TYPE_IP6_ROUTE));
-	return !obj->ip_route.table_coerced;
+	return nm_platform_route_table_is_main (obj->ip_route.table_coerced);
 }
 
 gboolean
@@ -2913,7 +2913,7 @@ nm_platform_lookup_predicate_routes_main_skip_rtprot_kernel (const NMPObject *ob
 {
 	nm_assert (NM_IN_SET (NMP_OBJECT_GET_TYPE (obj), NMP_OBJECT_TYPE_IP4_ROUTE,
 	                                                 NMP_OBJECT_TYPE_IP6_ROUTE));
-	return    !obj->ip_route.table_coerced
+	return    nm_platform_route_table_is_main (obj->ip_route.table_coerced)
 	       && obj->ip_route.rt_source != NM_IP_CONFIG_SOURCE_RTPROT_KERNEL;
 }
 
@@ -3828,12 +3828,14 @@ nm_platform_ip_route_normalize (int addr_family,
 	switch (addr_family) {
 	case AF_INET:
 		r4 = (NMPlatformIP4Route *) route;
+		r4->table_coerced = nm_platform_route_table_coerce (nm_platform_route_table_uncoerce (r4->table_coerced, TRUE));
 		r4->network = nm_utils_ip4_address_clear_host_address (r4->network, r4->plen);
 		r4->rt_source = nmp_utils_ip_config_source_round_trip_rtprot (r4->rt_source);
 		r4->scope_inv = _ip_route_scope_inv_get_normalized (r4);
 		break;
 	case AF_INET6:
 		r6 = (NMPlatformIP6Route *) route;
+		r6->table_coerced = nm_platform_route_table_coerce (nm_platform_route_table_uncoerce (r6->table_coerced, TRUE));
 		nm_utils_ip6_address_clear_host_address (&r6->network, &r6->network, r6->plen);
 		r6->rt_source = nmp_utils_ip_config_source_round_trip_rtprot (r6->rt_source),
 		r6->metric = nm_utils_ip6_route_metric_normalize (r6->metric);
@@ -4942,7 +4944,7 @@ nm_platform_ip4_route_to_string (const NMPlatformIP4Route *route, char *buf, gsi
 	            "%s" /* initrwnd */
 	            "%s" /* mtu */
 	            "",
-	            route->table_coerced ? nm_sprintf_buf (str_table, "table %u ", nm_platform_route_table_coerce (route->table_coerced)) : "",
+	            route->table_coerced ? nm_sprintf_buf (str_table, "table %u ", nm_platform_route_table_uncoerce (route->table_coerced, FALSE)) : "",
 	            s_network,
 	            route->plen,
 	            s_gateway,
@@ -5015,7 +5017,7 @@ nm_platform_ip6_route_to_string (const NMPlatformIP6Route *route, char *buf, gsi
 	            "%s" /* initrwnd */
 	            "%s" /* mtu */
 	            "",
-	            route->table_coerced ? nm_sprintf_buf (str_table, "table %u ", nm_platform_route_table_coerce (route->table_coerced)) : "",
+	            route->table_coerced ? nm_sprintf_buf (str_table, "table %u ", nm_platform_route_table_uncoerce (route->table_coerced, FALSE)) : "",
 	            s_network,
 	            route->plen,
 	            s_gateway,
@@ -5458,7 +5460,7 @@ nm_platform_ip4_route_hash (const NMPlatformIP4Route *obj, NMPlatformIPRouteCmpT
 		switch (cmp_type) {
 		case NM_PLATFORM_IP_ROUTE_CMP_TYPE_WEAK_ID:
 		case NM_PLATFORM_IP_ROUTE_CMP_TYPE_ID:
-			h = NM_HASH_COMBINE (h, obj->table_coerced);
+			h = NM_HASH_COMBINE (h, nm_platform_route_table_uncoerce (obj->table_coerced, TRUE));
 			h = NM_HASH_COMBINE (h, nm_utils_ip4_address_clear_host_address (obj->network, obj->plen));
 			h = NM_HASH_COMBINE (h, obj->plen);
 			h = NM_HASH_COMBINE (h, obj->metric);
@@ -5484,7 +5486,10 @@ nm_platform_ip4_route_hash (const NMPlatformIP4Route *obj, NMPlatformIPRouteCmpT
 			break;
 		case NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY:
 		case NM_PLATFORM_IP_ROUTE_CMP_TYPE_FULL:
-			h = NM_HASH_COMBINE (h, obj->table_coerced);
+			if (cmp_type == NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY)
+				h = NM_HASH_COMBINE (h, nm_platform_route_table_uncoerce (obj->table_coerced, TRUE));
+			else
+				h = NM_HASH_COMBINE (h, obj->table_coerced);
 			h = NM_HASH_COMBINE (h, obj->ifindex);
 			if (cmp_type == NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY)
 				h = NM_HASH_COMBINE (h, nm_utils_ip4_address_clear_host_address (obj->network, obj->plen));
@@ -5527,7 +5532,8 @@ nm_platform_ip4_route_cmp (const NMPlatformIP4Route *a, const NMPlatformIP4Route
 	switch (cmp_type) {
 	case NM_PLATFORM_IP_ROUTE_CMP_TYPE_WEAK_ID:
 	case NM_PLATFORM_IP_ROUTE_CMP_TYPE_ID:
-		NM_CMP_FIELD (a, b, table_coerced);
+		NM_CMP_DIRECT (nm_platform_route_table_uncoerce (a->table_coerced, TRUE),
+		               nm_platform_route_table_uncoerce (b->table_coerced, TRUE));
 		NM_CMP_DIRECT_IN4ADDR_SAME_PREFIX (a->network, b->network, MIN (a->plen, b->plen));
 		NM_CMP_FIELD (a, b, plen);
 		NM_CMP_FIELD (a, b, metric);
@@ -5555,7 +5561,11 @@ nm_platform_ip4_route_cmp (const NMPlatformIP4Route *a, const NMPlatformIP4Route
 		break;
 	case NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY:
 	case NM_PLATFORM_IP_ROUTE_CMP_TYPE_FULL:
-		NM_CMP_FIELD (a, b, table_coerced);
+		if (cmp_type == NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY) {
+			NM_CMP_DIRECT (nm_platform_route_table_uncoerce (a->table_coerced, TRUE),
+			               nm_platform_route_table_uncoerce (b->table_coerced, TRUE));
+		} else
+			NM_CMP_FIELD (a, b, table_coerced);
 		NM_CMP_FIELD (a, b, ifindex);
 		if (cmp_type == NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY)
 			NM_CMP_DIRECT_IN4ADDR_SAME_PREFIX (a->network, b->network, MIN (a->plen, b->plen));
@@ -5601,7 +5611,7 @@ nm_platform_ip6_route_hash (const NMPlatformIP6Route *obj, NMPlatformIPRouteCmpT
 		switch (cmp_type) {
 		case NM_PLATFORM_IP_ROUTE_CMP_TYPE_WEAK_ID:
 		case NM_PLATFORM_IP_ROUTE_CMP_TYPE_ID:
-			h = NM_HASH_COMBINE (h, obj->table_coerced);
+			h = NM_HASH_COMBINE (h, nm_platform_route_table_uncoerce (obj->table_coerced, TRUE));
 			h = NM_HASH_COMBINE_IN6ADDR_PREFIX (h, &obj->network, obj->plen);
 			h = NM_HASH_COMBINE (h, obj->plen);
 			h = NM_HASH_COMBINE (h, nm_utils_ip6_route_metric_normalize (obj->metric));
@@ -5614,7 +5624,10 @@ nm_platform_ip6_route_hash (const NMPlatformIP6Route *obj, NMPlatformIPRouteCmpT
 			break;
 		case NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY:
 		case NM_PLATFORM_IP_ROUTE_CMP_TYPE_FULL:
-			h = NM_HASH_COMBINE (h, obj->table_coerced);
+			if (cmp_type == NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY)
+				h = NM_HASH_COMBINE (h, nm_platform_route_table_uncoerce (obj->table_coerced, TRUE));
+			else
+				h = NM_HASH_COMBINE (h, obj->table_coerced);
 			h = NM_HASH_COMBINE (h, obj->ifindex);
 			if (cmp_type == NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY)
 				h = NM_HASH_COMBINE_IN6ADDR_PREFIX (h, &obj->network, obj->plen);
@@ -5661,7 +5674,8 @@ nm_platform_ip6_route_cmp (const NMPlatformIP6Route *a, const NMPlatformIP6Route
 	switch (cmp_type) {
 	case NM_PLATFORM_IP_ROUTE_CMP_TYPE_WEAK_ID:
 	case NM_PLATFORM_IP_ROUTE_CMP_TYPE_ID:
-		NM_CMP_FIELD (a, b, table_coerced);
+		NM_CMP_DIRECT (nm_platform_route_table_uncoerce (a->table_coerced, TRUE),
+		               nm_platform_route_table_uncoerce (b->table_coerced, TRUE));
 		NM_CMP_DIRECT_IN6ADDR_SAME_PREFIX (&a->network, &b->network, MIN (a->plen, b->plen));
 		NM_CMP_FIELD (a, b, plen);
 		NM_CMP_DIRECT (nm_utils_ip6_route_metric_normalize (a->metric), nm_utils_ip6_route_metric_normalize (b->metric));
@@ -5674,7 +5688,11 @@ nm_platform_ip6_route_cmp (const NMPlatformIP6Route *a, const NMPlatformIP6Route
 		break;
 	case NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY:
 	case NM_PLATFORM_IP_ROUTE_CMP_TYPE_FULL:
-		NM_CMP_FIELD (a, b, table_coerced);
+		if (cmp_type == NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY) {
+			NM_CMP_DIRECT (nm_platform_route_table_uncoerce (a->table_coerced, TRUE),
+			               nm_platform_route_table_uncoerce (b->table_coerced, TRUE));
+		} else
+			NM_CMP_FIELD (a, b, table_coerced);
 		NM_CMP_FIELD (a, b, ifindex);
 		if (cmp_type == NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY)
 			NM_CMP_DIRECT_IN6ADDR_SAME_PREFIX (&a->network, &b->network, MIN (a->plen, b->plen));
diff --git a/src/platform/nm-platform.h b/src/platform/nm-platform.h
index e68457ca2b..bbc268125c 100644
--- a/src/platform/nm-platform.h
+++ b/src/platform/nm-platform.h
@@ -426,7 +426,7 @@ typedef union {
 	 *
 	 * This is not the original table ID. Instead, 254 (RT_TABLE_MAIN) and
 	 * zero (RT_TABLE_UNSPEC) are swapped, so that the default is the main
-	 * table. Use nm_platform_route_table_coerce(). */ \
+	 * table. Use nm_platform_route_table_coerce()/nm_platform_route_table_uncoerce(). */ \
 	guint32 table_coerced; \
 	\
 	/*end*/
@@ -860,15 +860,21 @@ NMPlatform *nm_platform_get (void);
 
 /**
  * nm_platform_route_table_coerce:
- * @table: the route table, either its original value, or its coerced.
+ * @table: the route table, in its original value as received
+ *   from rtm_table/RTA_TABLE.
  *
- * Returns: returns the coerced table id. If the table id is like
- *   RTA_TABLE, it returns a value for NMPlatformIPRoute.table_coerced
- *   and vice versa.
+ * Returns: returns the coerced table id, that can be stored in
+ *   NMPlatformIPRoute.table_coerced.
  */
 static inline guint32
 nm_platform_route_table_coerce (guint32 table)
 {
+	/* For kernel, the default table is RT_TABLE_MAIN (254).
+	 * We want that in NMPlatformIPRoute.table_coerced a numeric
+	 * zero is the default. Hence, @table_coerced swaps the
+	 * value 0 and 254. Use nm_platform_route_table_coerce()
+	 * and nm_platform_route_table_uncoerce() to convert between
+	 * the two domains. */
 	switch (table) {
 	case 0 /* RT_TABLE_UNSPEC */:
 		return 254;
@@ -880,6 +886,45 @@ nm_platform_route_table_coerce (guint32 table)
 }
 
 /**
+ * nm_platform_route_table_uncoerce:
+ * @table: the route table, in its coerced value
+ * @normalize: whether to normalize RT_TABLE_UNSPEC to
+ *   RT_TABLE_MAIN. For kernel, routes with a table id
+ *   RT_TABLE_UNSPEC do not exist and are treated like
+ *   RT_TABLE_MAIN.
+ *
+ * Returns: reverts the coerced table ID in NMPlatformIPRoute.table_coerced
+ *   to the original value as kernel understands it.
+ */
+static inline guint32
+nm_platform_route_table_uncoerce (guint32 table_coerced, gboolean normalize)
+{
+	/* this undoes nm_platform_route_table_coerce().  */
+	switch (table_coerced) {
+	case 0 /* RT_TABLE_UNSPEC */:
+		return 254;
+	case 254 /* RT_TABLE_MAIN */:
+		return normalize ? 254 : 0;
+	default:
+		return table_coerced;
+	}
+}
+
+static inline gboolean
+nm_platform_route_table_is_main (guint32 table)
+{
+	/* same as
+	 *   nm_platform_route_table_uncoerce (table, TRUE) == RT_TABLE_MAIN
+	 * and
+	 *   nm_platform_route_table_uncoerce (nm_platform_route_table_coerce (table), TRUE) == RT_TABLE_MAIN
+	 *
+	 * That is, the function operates the same on @table and its coerced
+	 * form.
+	 */
+	return table == 0 || table == 254;
+}
+
+/**
  * nm_platform_route_scope_inv:
  * @scope: the route scope, either its original value, or its inverse.
  *