isisd: added support for routemap match tag in redistribution

Now it's possible to filter routes redistributed by another protocol using tag
which comes from zebra daemon.

Example of a possible configuration:

```
!
ipv6 route fd00::/48 blackhole tag 20
ipv6 route fd00::/60 blackhole tag 10
!
interface one
 ipv6 router isis COMMON
 isis circuit-type level-1
!
interface two
 ipv6 router isis COMMON
 isis circuit-type level-2-only
!
router isis COMMON
 net fd.0000.0000.0000.0001.00
 redistribute ipv6 static level-1 route-map static-l1
 redistribute ipv6 static level-2 route-map static-l2
 topology ipv6-unicast
!
route-map static-l1 permit 10
 match tag 10
!
route-map static-l2 permit 10
 match tag 20
!
```

Signed-off-by: Emanuele Altomare <emanuele@common-net.org>

1 files changed, 33 insertions, 0 deletions

diff --git a/isisd/isis_routemap.c b/isisd/isis_routemap.c
index db0f2fd8b..626e399e1 100644
--- a/isisd/isis_routemap.c
+++ b/isisd/isis_routemap.c
@@ -112,6 +112,35 @@ static const struct route_map_rule_cmd
 
 /* ------------------------------------------------------------*/
 
+/* `match tag TAG' */
+/* Match function return 1 if match is success else return zero. */
+static enum route_map_cmd_result_t
+route_match_tag(void *rule, const struct prefix *p, void *object)
+{
+	route_tag_t *tag;
+	struct isis_ext_info *info;
+	route_tag_t info_tag;
+
+	tag = rule;
+	info = object;
+
+	info_tag = info->tag;
+	if (info_tag == *tag)
+		return RMAP_MATCH;
+	else
+		return RMAP_NOMATCH;
+}
+
+/* Route map commands for tag matching. */
+static const struct route_map_rule_cmd route_match_tag_cmd = {
+	"tag",
+	route_match_tag,
+	route_map_rule_tag_compile,
+	route_map_rule_tag_free,
+};
+
+/* ------------------------------------------------------------*/
+
 static enum route_map_cmd_result_t
 route_match_ipv6_address(void *rule, const struct prefix *prefix, void *object)
 {
@@ -234,6 +263,9 @@ void isis_route_map_init(void)
 	route_map_match_ipv6_address_prefix_list_hook(generic_match_add);
 	route_map_no_match_ipv6_address_prefix_list_hook(generic_match_delete);
 
+	route_map_match_tag_hook(generic_match_add);
+	route_map_no_match_tag_hook(generic_match_delete);
+
 	route_map_set_metric_hook(generic_set_add);
 	route_map_no_set_metric_hook(generic_set_delete);
 
@@ -241,5 +273,6 @@ void isis_route_map_init(void)
 	route_map_install_match(&route_match_ip_address_prefix_list_cmd);
 	route_map_install_match(&route_match_ipv6_address_cmd);
 	route_map_install_match(&route_match_ipv6_address_prefix_list_cmd);
+	route_map_install_match(&route_match_tag_cmd);
 	route_map_install_set(&route_set_metric_cmd);
 }