From db276bcc801cbd2662f90a6b22cfc551ecddbf0f Mon Sep 17 00:00:00 2001 From: Benjamin Cama Date: Wed, 20 Jul 2011 14:45:09 +0200 Subject: [PATCH] Handle multiprotocol UPDATE. Add IPv6 routes advertisement handling, with MP path attributes heading prepared on initialization. BTW, fix a bug in attribute size calculation (for extended attr). Signed-off-by: Benjamin Cama --- bgp.c | 201 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ bgp.h | 22 ++++++- 2 files changed, 222 insertions(+), 1 deletion(-) diff --git a/bgp.c b/bgp.c index 1e1713d..d9c5818 100644 --- a/bgp.c +++ b/bgp.c @@ -250,6 +250,51 @@ int bgp_start(struct bgp_peer *peer, char *name, int as, int keepalive, memcpy(peer->path_attrs, path_attrs, peer->path_attr_len); + /* multiprotocol attributes initialization */ + if (config->ipv6_prefix.s6_addr[0]) + { + struct bgp_attr_mp_reach_nlri_partial mp_reach_nlri_partial; + struct bgp_attr_mp_unreach_nlri_partial mp_unreach_nlri_partial; + + a.flags = BGP_PATH_ATTR_FLAG_OPTIONAL; + a.code = BGP_PATH_ATTR_CODE_MP_REACH_NLRI; + a.data.s.len = 0; /* will be set on UPDATE */ + + mp_reach_nlri_partial.afi = htons(AF_INET6); + mp_reach_nlri_partial.safi = BGP_MP_SAFI_UNICAST; + mp_reach_nlri_partial.reserved = 0; + mp_reach_nlri_partial.next_hop_len = 16; + + /* use the defined nexthop6, or our address in ipv6_prefix */ + if (config->nexthop6_address.s6_addr[0]) + memcpy(&mp_reach_nlri_partial.next_hop, + &config->nexthop6_address.s6_addr, 16); + else + { + /* our address is ipv6prefix::1 */ + memcpy(&mp_reach_nlri_partial.next_hop, + &config->ipv6_prefix.s6_addr, 16); + mp_reach_nlri_partial.next_hop[15] = 1; + } + + memcpy(&a.data.s.value, &mp_reach_nlri_partial, + sizeof(struct bgp_attr_mp_reach_nlri_partial)); + memcpy(&peer->mp_reach_nlri_partial, &a, + BGP_PATH_ATTR_MP_REACH_NLRI_PARTIAL_SIZE); + + a.flags = BGP_PATH_ATTR_FLAG_OPTIONAL | BGP_PATH_ATTR_FLAG_EXTLEN; + a.code = BGP_PATH_ATTR_CODE_MP_UNREACH_NLRI; + a.data.e.len = 0; /* will be set on UPDATE */ + + mp_unreach_nlri_partial.afi = htons(AF_INET6); + mp_unreach_nlri_partial.safi = BGP_MP_SAFI_UNICAST; + + memcpy(&a.data.e.value, &mp_unreach_nlri_partial, + sizeof(struct bgp_attr_mp_unreach_nlri_partial)); + memcpy(&peer->mp_unreach_nlri_partial, &a, + BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE); + } + LOG(4, 0, 0, "Initiating BGP connection to %s (routing %s)\n", name, enable ? "enabled" : "suspended"); @@ -1492,6 +1537,162 @@ static int bgp_send_update(struct bgp_peer *peer) /* send/buffer UPDATE message for IPv6 routes */ static int bgp_send_update6(struct bgp_peer *peer) { + uint16_t unf_len = 0; + uint16_t attr_len; + char *unreach_len; + uint8_t reach_len; + uint16_t len = sizeof(peer->outbuf->packet.header); + struct bgp_route6_list *have = peer->routes6; + struct bgp_route6_list *want = peer->routing ? bgp_routes6 : 0; + struct bgp_route6_list *e = 0; + struct bgp_route6_list *add = 0; + int s; + char ipv6addr[INET6_ADDRSTRLEN]; + + char *data = (char *) &peer->outbuf->packet.data; + + /* need leave room for attr_len, bgp_path_attrs and one prefix */ + char *max = (char *) &peer->outbuf->packet.data + + sizeof(peer->outbuf->packet.data) + - sizeof(attr_len) - peer->path_attr_len_without_nexthop + - BGP_PATH_ATTR_MP_REACH_NLRI_PARTIAL_SIZE - sizeof(struct bgp_ip6_prefix); + + memset(peer->outbuf->packet.header.marker, 0xff, + sizeof(peer->outbuf->packet.header.marker)); + + peer->outbuf->packet.header.type = BGP_MSG_UPDATE; + + /* insert non-MP unf_len */ + memcpy(data, &unf_len, sizeof(unf_len)); + /* skip over attr_len too; will be filled when known */ + data += sizeof(unf_len) + sizeof(attr_len); + len += sizeof(unf_len) + sizeof(attr_len); + + /* copy usual attributes */ + memcpy(data, peer->path_attrs, peer->path_attr_len_without_nexthop); + data += peer->path_attr_len_without_nexthop; + len += peer->path_attr_len_without_nexthop; + + /* copy MP unreachable NLRI heading */ + memcpy(data, peer->mp_unreach_nlri_partial, + BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE); + /* remember where to update this attr len */ + unreach_len = data + 2; + data += BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE; + len += BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE; + + peer->update_routes6 = 0; /* tentatively clear */ + + /* find differences */ + while ((have || want) && data < (max - sizeof(struct bgp_ip6_prefix))) + { + if (have) + s = want + ? memcmp(&have->dest, &want->dest, sizeof(have->dest)) + : -1; + else + s = 1; + + if (s < 0) /* found one to delete */ + { + struct bgp_route6_list *tmp = have; + have = have->next; + + s = BGP_IP_PREFIX_SIZE(tmp->dest); + memcpy(data, &tmp->dest, s); + data += s; + unf_len += s; + len += s; + + LOG(5, 0, 0, "Withdrawing route %s/%d from BGP peer %s\n", + inet_ntop(AF_INET6, &tmp->dest.prefix, ipv6addr, INET6_ADDRSTRLEN), + tmp->dest.len, peer->name); + + free(tmp); + + if (e) + e->next = have; + else + peer->routes6 = have; + } + else + { + if (!s) /* same */ + { + e = have; /* stash the last found to relink above */ + have = have->next; + want = want->next; + } + else if (s > 0) /* addition reqd. */ + { + if (add) + { + peer->update_routes6 = 1; /* only one add per packet */ + if (!have) + break; + } + else + add = want; + + if (want) + want = want->next; + } + } + } + + if (have || want) + peer->update_routes6 = 1; /* more to do */ + + /* anything changed? */ + if (!(unf_len || add)) + return 1; + + /* go back and insert MP unf_len */ + unf_len += sizeof(struct bgp_attr_mp_unreach_nlri_partial); + unf_len = htons(unf_len); + memcpy(&unreach_len, &unf_len, sizeof(unf_len)); + + if (add) + { + if (!(e = malloc(sizeof(*e)))) + { + LOG(0, 0, 0, "Can't allocate route for %s/%d (%s)\n", + inet_ntop(AF_INET6, &add->dest.prefix, ipv6addr, INET6_ADDRSTRLEN), + add->dest.len, strerror(errno)); + + return 0; + } + + memcpy(e, add, sizeof(*e)); + e->next = 0; + peer->routes6 = bgp_insert_route6(peer->routes6, e); + + /* copy MP reachable NLRI heading */ + memcpy(data, peer->mp_reach_nlri_partial, + BGP_PATH_ATTR_MP_REACH_NLRI_PARTIAL_SIZE); + /* with proper len */ + reach_len = BGP_IP_PREFIX_SIZE(add->dest); + data[2] = reach_len; + data += BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE; + len += BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE; + + memcpy(data, &add->dest, reach_len); + data += reach_len; + len += reach_len; + + LOG(5, 0, 0, "Advertising route %s/%d to BGP peer %s\n", + inet_ntop(AF_INET6, &add->dest.prefix, ipv6addr, INET6_ADDRSTRLEN), + add->dest.len, peer->name); + } + + /* go back and insert attr_len */ + attr_len = htons(len - 4); + memcpy(&peer->outbuf->packet.data + 2, &attr_len, sizeof(attr_len)); + + peer->outbuf->packet.header.len = htons(len); + peer->outbuf->done = 0; + + return bgp_write(peer); } /* send/buffer NOTIFICATION message */ diff --git a/bgp.h b/bgp.h index db8b1ae..6dbfbf8 100644 --- a/bgp.h +++ b/bgp.h @@ -101,6 +101,22 @@ struct bgp_path_attr { } data; /* variable */ } __attribute__ ((packed)); +struct bgp_attr_mp_reach_nlri_partial { + uint16_t afi; /* sa_family_t */ + uint8_t safi; + uint8_t next_hop_len; + uint8_t next_hop[16]; + uint8_t reserved; +} __attribute__ ((packed)); +#define BGP_PATH_ATTR_MP_REACH_NLRI_PARTIAL_SIZE (3 + sizeof(struct bgp_attr_mp_reach_nlri_partial)) + +struct bgp_attr_mp_unreach_nlri_partial { + uint16_t afi; /* sa_family_t */ + uint8_t safi; +} __attribute__ ((packed)); +/* we use it as an extended attribute */ +#define BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE (4 + sizeof(struct bgp_attr_mp_unreach_nlri_partial)) + /* bgp_path_attr.flags (bitfields) */ #define BGP_PATH_ATTR_FLAG_OPTIONAL (1 << 7) #define BGP_PATH_ATTR_FLAG_TRANS (1 << 6) @@ -121,9 +137,11 @@ struct bgp_path_attr { #define BGP_PATH_ATTR_CODE_ATOMIC_AGGREGATE 6 /* well-known, discretionary */ #define BGP_PATH_ATTR_CODE_AGGREGATOR 7 /* optional, transitive */ #define BGP_PATH_ATTR_CODE_COMMUNITIES 8 /* optional, transitive (RFC1997) */ +#define BGP_PATH_ATTR_CODE_MP_REACH_NLRI 14 /* optional, non-transitive (RFC4760) */ +#define BGP_PATH_ATTR_CODE_MP_UNREACH_NLRI 15 /* optional, non-transitive (RFC4760) */ #define BGP_PATH_ATTR_SIZE(p) ((((p).flags & BGP_PATH_ATTR_FLAG_EXTLEN) \ - ? ((p).data.e.len + 1) : (p).data.s.len) + 3) + ? ((p).data.e.len + 4) : (p).data.s.len) + 3) /* well known COMMUNITIES */ #define BGP_COMMUNITY_NO_EXPORT 0xffffff01 /* don't advertise outside confederation */ @@ -222,6 +240,8 @@ struct bgp_peer { int handle_ipv6_routes; /* can handle IPv6 routes advertisements */ int update_routes6; /* UPDATE required for IPv6 routes */ struct bgp_route6_list *routes6; /* IPv6 routes known by this peer */ + char mp_reach_nlri_partial[BGP_PATH_ATTR_MP_REACH_NLRI_PARTIAL_SIZE]; + char mp_unreach_nlri_partial[BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE]; }; /* bgp_peer.cli_flag */ -- 2.20.1