Support for BGP Large Communities

BGP Large Communities are a novel way to signal information between
networks. An example of a Large Community is: "2914:65400:38016". Large
BGP Communities are composed of three 4-byte integers, separated by a
colon. This is easy to remember and accommodates advanced routing
policies in relation to 4-Byte ASNs.

This feature was developed by:
Keyur Patel <keyur@arrcus.com> (Arrcus, Inc.),
Job Snijders <job@ntt.net> (NTT Communications),
David Lamparter <equinox@opensourcerouting.org>
and Donald Sharp <sharpd@cumulusnetworks.com>

Signed-off-by: Job Snijders <job@ntt.net>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>

Author: job

bgpd/Makefile.am

@@ -75,7 +75,8 @@ libbgp_a_SOURCES = \
 	bgpd.c bgp_fsm.c bgp_aspath.c bgp_community.c bgp_attr.c \
 	bgp_debug.c bgp_route.c bgp_zebra.c bgp_open.c bgp_routemap.c \
 	bgp_packet.c bgp_network.c bgp_filter.c bgp_regex.c bgp_clist.c \
-	bgp_dump.c bgp_snmp.c bgp_ecommunity.c bgp_mplsvpn.c bgp_nexthop.c \
+	bgp_dump.c bgp_snmp.c bgp_ecommunity.c bgp_lcommunity.c \
+	bgp_mplsvpn.c bgp_nexthop.c \
 	bgp_damp.c bgp_table.c bgp_advertise.c bgp_vty.c bgp_mpath.c \
         bgp_nht.c bgp_updgrp.c bgp_updgrp_packet.c bgp_updgrp_adv.c bgp_bfd.c \
 	bgp_encap.c bgp_encap_tlv.c $(BGP_VNC_RFAPI_SRC)
@@ -85,7 +86,8 @@ noinst_HEADERS = \
 	bgp_aspath.h bgp_attr.h bgp_community.h bgp_debug.h bgp_fsm.h \
 	bgp_network.h bgp_open.h bgp_packet.h bgp_regex.h bgp_route.h \
 	bgpd.h bgp_filter.h bgp_clist.h bgp_dump.h bgp_zebra.h \
-	bgp_ecommunity.h bgp_mplsvpn.h bgp_nexthop.h bgp_damp.h bgp_table.h \
+	bgp_ecommunity.h bgp_lcommunity.h \
+	bgp_mplsvpn.h bgp_nexthop.h bgp_damp.h bgp_table.h \
 	bgp_advertise.h bgp_snmp.h bgp_vty.h bgp_mpath.h bgp_nht.h \
         bgp_updgrp.h bgp_bfd.h bgp_encap.h bgp_encap_tlv.h bgp_encap_types.h \
 	$(BGP_VNC_RFAPI_HD) 

bgpd/bgp_attr.c

@@ -42,6 +42,7 @@ Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 #include "bgpd/bgp_debug.h"
 #include "bgpd/bgp_packet.h"
 #include "bgpd/bgp_ecommunity.h"
+#include "bgpd/bgp_lcommunity.h"
 #include "bgpd/bgp_updgrp.h"
 #include "bgpd/bgp_encap_types.h"
 #if ENABLE_BGP_VNC
@@ -76,6 +77,7 @@ static const struct message attr_str [] =
 #if ENABLE_BGP_VNC
   { BGP_ATTR_VNC,              "VNC" },
 #endif
+  { BGP_ATTR_LARGE_COMMUNITIES, "LARGE_COMMUNITY" }
 };
 static const int attr_str_max = array_size(attr_str);
 
@@ -670,6 +672,8 @@ attrhash_key_make (void *p)
 
   if (extra)
     {
+      if (extra->lcommunity)
+	MIX(lcommunity_hash_make (extra->lcommunity));
       if (extra->ecommunity)
         MIX(ecommunity_hash_make (extra->ecommunity));
       if (extra->cluster)
@@ -718,6 +722,7 @@ attrhash_cmp (const void *p1, const void *p2)
           && IPV6_ADDR_SAME (&ae1->mp_nexthop_local, &ae2->mp_nexthop_local)
           && IPV4_ADDR_SAME (&ae1->mp_nexthop_global_in, &ae2->mp_nexthop_global_in)
           && ae1->ecommunity == ae2->ecommunity
+	  && ae1->lcommunity == ae2->lcommunity
           && ae1->cluster == ae2->cluster
           && ae1->transit == ae2->transit
 	  && (ae1->encap_tunneltype == ae2->encap_tunneltype)
@@ -836,6 +841,13 @@ bgp_attr_intern (struct attr *attr)
             attre->ecommunity->refcnt++;
 
         }
+      if (attre->lcommunity)
+        {
+          if (! attre->lcommunity->refcnt)
+            attre->lcommunity = lcommunity_intern (attre->lcommunity);
+          else
+            attre->lcommunity->refcnt++;
+        }
       if (attre->cluster)
         {
           if (! attre->cluster->refcnt)
@@ -1026,6 +1038,10 @@ bgp_attr_unintern_sub (struct attr *attr)
       if (attr->extra->ecommunity)
         ecommunity_unintern (&attr->extra->ecommunity);
       UNSET_FLAG(attr->flag, ATTR_FLAG_BIT (BGP_ATTR_EXT_COMMUNITIES));
+
+      if (attr->extra->lcommunity)
+        lcommunity_unintern (&attr->extra->lcommunity);
+      UNSET_FLAG(attr->flag, ATTR_FLAG_BIT (BGP_ATTR_LARGE_COMMUNITIES));
 
       if (attr->extra->cluster)
         cluster_unintern (attr->extra->cluster);
@@ -1096,6 +1112,8 @@ bgp_attr_flush (struct attr *attr)
 
       if (attre->ecommunity && ! attre->ecommunity->refcnt)
         ecommunity_free (&attre->ecommunity);
+      if (attre->lcommunity && ! attre->lcommunity->refcnt)
+	lcommunity_free (&attre->lcommunity);
       if (attre->cluster && ! attre->cluster->refcnt)
         {
           cluster_free (attre->cluster);
@@ -1254,6 +1272,7 @@ const u_int8_t attr_flags_values [] = {
   [BGP_ATTR_EXT_COMMUNITIES] =  BGP_ATTR_FLAG_OPTIONAL | BGP_ATTR_FLAG_TRANS,
   [BGP_ATTR_AS4_PATH] =         BGP_ATTR_FLAG_OPTIONAL | BGP_ATTR_FLAG_TRANS,
   [BGP_ATTR_AS4_AGGREGATOR] =   BGP_ATTR_FLAG_OPTIONAL | BGP_ATTR_FLAG_TRANS,
+  [BGP_ATTR_LARGE_COMMUNITIES] = BGP_ATTR_FLAG_TRANS | BGP_ATTR_FLAG_OPTIONAL
 };
 static const size_t attr_flags_values_max = array_size(attr_flags_values) - 1;
 
@@ -2042,6 +2061,40 @@ bgp_mp_unreach_parse (struct bgp_attr_parser_args *args,
   return BGP_ATTR_PARSE_PROCEED;
 }
 
+/* Large Community attribute. */
+static bgp_attr_parse_ret_t
+bgp_attr_large_community (struct bgp_attr_parser_args *args)
+{
+  struct peer *const peer = args->peer;
+  struct attr *const attr = args->attr;
+  const bgp_size_t length = args->length;
+
+  /*
+   * Large community follows new attribute format.
+   */
+  if (length == 0)
+    {
+      if (attr->extra)
+        attr->extra->lcommunity = NULL;
+      /* Empty extcomm doesn't seem to be invalid per se */
+      return BGP_ATTR_PARSE_PROCEED;
+    }
+
+  (bgp_attr_extra_get (attr))->lcommunity =
+    lcommunity_parse ((u_int8_t *)stream_pnt (peer->ibuf), length);
+  /* XXX: fix ecommunity_parse to use stream API */
+  stream_forward_getp (peer->ibuf, length);
+
+  if (attr->extra && !attr->extra->lcommunity)
+    return bgp_attr_malformed (args,
+                               BGP_NOTIFY_UPDATE_OPT_ATTR_ERR,
+                               args->total);
+
+  attr->flag |= ATTR_FLAG_BIT (BGP_ATTR_LARGE_COMMUNITIES);
+
+  return BGP_ATTR_PARSE_PROCEED;
+}
+
 /* Extended Community attribute. */
 static bgp_attr_parse_ret_t
 bgp_attr_ext_communities (struct bgp_attr_parser_args *args)
@@ -2063,7 +2116,7 @@ bgp_attr_ext_communities (struct bgp_attr_parser_args *args)
   /* XXX: fix ecommunity_parse to use stream API */
   stream_forward_getp (peer->ibuf, length);
 
-  if (!attr->extra->ecommunity)
+  if (attr->extra && !attr->extra->ecommunity)
     return bgp_attr_malformed (args,
                                BGP_NOTIFY_UPDATE_OPT_ATTR_ERR,
                                args->total);
@@ -2477,6 +2530,9 @@ bgp_attr_parse (struct peer *peer, struct attr *attr, bgp_size_t size,
 	case BGP_ATTR_COMMUNITIES:
 	  ret = bgp_attr_community (&attr_args);
 	  break;
+	case BGP_ATTR_LARGE_COMMUNITIES:
+	  ret = bgp_attr_large_community (&attr_args);
+	  break;
 	case BGP_ATTR_ORIGINATOR_ID:
 	  ret = bgp_attr_originator_id (&attr_args);
 	  break;
@@ -3101,6 +3157,28 @@ bgp_packet_attribute (struct bgp *bgp, struct peer *peer,
       stream_put (s, attr->community->val, attr->community->size * 4);
     }
 
+  /*
+   * Large Community attribute.
+   */
+  if (attr->extra &&
+      CHECK_FLAG (peer->af_flags[afi][safi], PEER_FLAG_SEND_LARGE_COMMUNITY)
+      && (attr->flag & ATTR_FLAG_BIT (BGP_ATTR_LARGE_COMMUNITIES)))
+    {
+      if (attr->extra->lcommunity->size * 12 > 255)
+	{
+	  stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS|BGP_ATTR_FLAG_EXTLEN);
+	  stream_putc (s, BGP_ATTR_LARGE_COMMUNITIES);
+	  stream_putw (s, attr->extra->lcommunity->size * 12);
+	}
+      else
+	{
+	  stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS);
+	  stream_putc (s, BGP_ATTR_LARGE_COMMUNITIES);
+	  stream_putc (s, attr->extra->lcommunity->size * 12);
+	}
+      stream_put (s, attr->extra->lcommunity->val, attr->extra->lcommunity->size * 12);
+    }
+
   /* Route Reflector. */
   if (peer->sort == BGP_PEER_IBGP
       && from
@@ -3333,6 +3411,7 @@ bgp_attr_init (void)
   attrhash_init ();
   community_init ();
   ecommunity_init ();
+  lcommunity_init ();
   cluster_init ();
   transit_init ();
   encap_init ();
@@ -3345,6 +3424,7 @@ bgp_attr_finish (void)
   attrhash_finish ();
   community_finish ();
   ecommunity_finish ();
+  lcommunity_finish ();
   cluster_finish ();
   transit_finish ();
   encap_finish ();
@@ -3448,6 +3528,25 @@ bgp_dump_routes_attr (struct stream *s, struct attr *attr,
       stream_put (s, attr->community->val, attr->community->size * 4);
     }
 
+  /* Large Community attribute. */
+  if (attr->extra && attr->flag & ATTR_FLAG_BIT (BGP_ATTR_LARGE_COMMUNITIES))
+    {
+      if (attr->extra->lcommunity->size * 12 > 255)
+	{
+	  stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS|BGP_ATTR_FLAG_EXTLEN);
+	  stream_putc (s, BGP_ATTR_LARGE_COMMUNITIES);
+	  stream_putw (s, attr->extra->lcommunity->size * 12);
+	}
+      else
+	{
+	  stream_putc (s, BGP_ATTR_FLAG_OPTIONAL|BGP_ATTR_FLAG_TRANS);
+	  stream_putc (s, BGP_ATTR_LARGE_COMMUNITIES);
+	  stream_putc (s, attr->extra->lcommunity->size * 12);
+	}
+
+      stream_put (s, attr->extra->lcommunity->val, attr->extra->lcommunity->size * 12);
+    }
+
   /* Add a MP_NLRI attribute to dump the IPv6 next hop */
   if (prefix != NULL && prefix->family == AF_INET6 && attr->extra &&
      (attr->extra->mp_nexthop_len == BGP_ATTR_NHLEN_IPV6_GLOBAL ||

bgpd/bgp_attr.h

@@ -92,6 +92,9 @@ struct attr_extra
 
   /* Extended Communities attribute. */
   struct ecommunity *ecommunity;
+
+  /* Large Communities attribute. */
+  struct lcommunity *lcommunity;
 
   /* Route-Reflector Cluster attribute */
   struct cluster_list *cluster;