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 <benoar@dolka.fr>
This commit is contained in:
Benjamin Cama
parent
59411b8799
commit
db276bcc80
2 changed files with 222 additions and 1 deletions
201
bgp.c
201
bgp.c
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@ -250,6 +250,51 @@ int bgp_start(struct bgp_peer *peer, char *name, int as, int keepalive,
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memcpy(peer->path_attrs, path_attrs, peer->path_attr_len);
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/* multiprotocol attributes initialization */
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if (config->ipv6_prefix.s6_addr[0])
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{
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struct bgp_attr_mp_reach_nlri_partial mp_reach_nlri_partial;
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struct bgp_attr_mp_unreach_nlri_partial mp_unreach_nlri_partial;
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a.flags = BGP_PATH_ATTR_FLAG_OPTIONAL;
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a.code = BGP_PATH_ATTR_CODE_MP_REACH_NLRI;
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a.data.s.len = 0; /* will be set on UPDATE */
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mp_reach_nlri_partial.afi = htons(AF_INET6);
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mp_reach_nlri_partial.safi = BGP_MP_SAFI_UNICAST;
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mp_reach_nlri_partial.reserved = 0;
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mp_reach_nlri_partial.next_hop_len = 16;
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/* use the defined nexthop6, or our address in ipv6_prefix */
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if (config->nexthop6_address.s6_addr[0])
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memcpy(&mp_reach_nlri_partial.next_hop,
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&config->nexthop6_address.s6_addr, 16);
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else
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{
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/* our address is ipv6prefix::1 */
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memcpy(&mp_reach_nlri_partial.next_hop,
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&config->ipv6_prefix.s6_addr, 16);
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mp_reach_nlri_partial.next_hop[15] = 1;
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}
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memcpy(&a.data.s.value, &mp_reach_nlri_partial,
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sizeof(struct bgp_attr_mp_reach_nlri_partial));
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memcpy(&peer->mp_reach_nlri_partial, &a,
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BGP_PATH_ATTR_MP_REACH_NLRI_PARTIAL_SIZE);
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a.flags = BGP_PATH_ATTR_FLAG_OPTIONAL | BGP_PATH_ATTR_FLAG_EXTLEN;
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a.code = BGP_PATH_ATTR_CODE_MP_UNREACH_NLRI;
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a.data.e.len = 0; /* will be set on UPDATE */
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mp_unreach_nlri_partial.afi = htons(AF_INET6);
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mp_unreach_nlri_partial.safi = BGP_MP_SAFI_UNICAST;
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memcpy(&a.data.e.value, &mp_unreach_nlri_partial,
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sizeof(struct bgp_attr_mp_unreach_nlri_partial));
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memcpy(&peer->mp_unreach_nlri_partial, &a,
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BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE);
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}
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LOG(4, 0, 0, "Initiating BGP connection to %s (routing %s)\n",
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name, enable ? "enabled" : "suspended");
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@ -1492,6 +1537,162 @@ static int bgp_send_update(struct bgp_peer *peer)
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/* send/buffer UPDATE message for IPv6 routes */
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static int bgp_send_update6(struct bgp_peer *peer)
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{
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uint16_t unf_len = 0;
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uint16_t attr_len;
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char *unreach_len;
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uint8_t reach_len;
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uint16_t len = sizeof(peer->outbuf->packet.header);
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struct bgp_route6_list *have = peer->routes6;
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struct bgp_route6_list *want = peer->routing ? bgp_routes6 : 0;
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struct bgp_route6_list *e = 0;
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struct bgp_route6_list *add = 0;
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int s;
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char ipv6addr[INET6_ADDRSTRLEN];
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char *data = (char *) &peer->outbuf->packet.data;
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/* need leave room for attr_len, bgp_path_attrs and one prefix */
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char *max = (char *) &peer->outbuf->packet.data
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+ sizeof(peer->outbuf->packet.data)
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- sizeof(attr_len) - peer->path_attr_len_without_nexthop
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- BGP_PATH_ATTR_MP_REACH_NLRI_PARTIAL_SIZE - sizeof(struct bgp_ip6_prefix);
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memset(peer->outbuf->packet.header.marker, 0xff,
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sizeof(peer->outbuf->packet.header.marker));
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peer->outbuf->packet.header.type = BGP_MSG_UPDATE;
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/* insert non-MP unf_len */
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memcpy(data, &unf_len, sizeof(unf_len));
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/* skip over attr_len too; will be filled when known */
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data += sizeof(unf_len) + sizeof(attr_len);
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len += sizeof(unf_len) + sizeof(attr_len);
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/* copy usual attributes */
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memcpy(data, peer->path_attrs, peer->path_attr_len_without_nexthop);
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data += peer->path_attr_len_without_nexthop;
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len += peer->path_attr_len_without_nexthop;
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/* copy MP unreachable NLRI heading */
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memcpy(data, peer->mp_unreach_nlri_partial,
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BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE);
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/* remember where to update this attr len */
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unreach_len = data + 2;
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data += BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE;
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len += BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE;
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peer->update_routes6 = 0; /* tentatively clear */
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/* find differences */
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while ((have || want) && data < (max - sizeof(struct bgp_ip6_prefix)))
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{
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if (have)
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s = want
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? memcmp(&have->dest, &want->dest, sizeof(have->dest))
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: -1;
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else
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s = 1;
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if (s < 0) /* found one to delete */
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{
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struct bgp_route6_list *tmp = have;
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have = have->next;
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s = BGP_IP_PREFIX_SIZE(tmp->dest);
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memcpy(data, &tmp->dest, s);
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data += s;
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unf_len += s;
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len += s;
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LOG(5, 0, 0, "Withdrawing route %s/%d from BGP peer %s\n",
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inet_ntop(AF_INET6, &tmp->dest.prefix, ipv6addr, INET6_ADDRSTRLEN),
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tmp->dest.len, peer->name);
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free(tmp);
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if (e)
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e->next = have;
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else
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peer->routes6 = have;
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}
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else
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{
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if (!s) /* same */
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{
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e = have; /* stash the last found to relink above */
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have = have->next;
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want = want->next;
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}
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else if (s > 0) /* addition reqd. */
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{
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if (add)
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{
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peer->update_routes6 = 1; /* only one add per packet */
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if (!have)
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break;
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}
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else
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add = want;
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if (want)
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want = want->next;
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}
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}
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}
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if (have || want)
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peer->update_routes6 = 1; /* more to do */
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/* anything changed? */
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if (!(unf_len || add))
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return 1;
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/* go back and insert MP unf_len */
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unf_len += sizeof(struct bgp_attr_mp_unreach_nlri_partial);
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unf_len = htons(unf_len);
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memcpy(&unreach_len, &unf_len, sizeof(unf_len));
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if (add)
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{
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if (!(e = malloc(sizeof(*e))))
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{
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LOG(0, 0, 0, "Can't allocate route for %s/%d (%s)\n",
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inet_ntop(AF_INET6, &add->dest.prefix, ipv6addr, INET6_ADDRSTRLEN),
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add->dest.len, strerror(errno));
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return 0;
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}
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memcpy(e, add, sizeof(*e));
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e->next = 0;
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peer->routes6 = bgp_insert_route6(peer->routes6, e);
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/* copy MP reachable NLRI heading */
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memcpy(data, peer->mp_reach_nlri_partial,
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BGP_PATH_ATTR_MP_REACH_NLRI_PARTIAL_SIZE);
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/* with proper len */
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reach_len = BGP_IP_PREFIX_SIZE(add->dest);
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data[2] = reach_len;
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data += BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE;
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len += BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE;
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memcpy(data, &add->dest, reach_len);
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data += reach_len;
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len += reach_len;
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LOG(5, 0, 0, "Advertising route %s/%d to BGP peer %s\n",
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inet_ntop(AF_INET6, &add->dest.prefix, ipv6addr, INET6_ADDRSTRLEN),
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add->dest.len, peer->name);
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}
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/* go back and insert attr_len */
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attr_len = htons(len - 4);
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memcpy(&peer->outbuf->packet.data + 2, &attr_len, sizeof(attr_len));
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peer->outbuf->packet.header.len = htons(len);
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peer->outbuf->done = 0;
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return bgp_write(peer);
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}
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/* send/buffer NOTIFICATION message */
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22
bgp.h
22
bgp.h
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@ -101,6 +101,22 @@ struct bgp_path_attr {
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} data; /* variable */
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} __attribute__ ((packed));
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struct bgp_attr_mp_reach_nlri_partial {
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uint16_t afi; /* sa_family_t */
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uint8_t safi;
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uint8_t next_hop_len;
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uint8_t next_hop[16];
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uint8_t reserved;
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} __attribute__ ((packed));
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#define BGP_PATH_ATTR_MP_REACH_NLRI_PARTIAL_SIZE (3 + sizeof(struct bgp_attr_mp_reach_nlri_partial))
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struct bgp_attr_mp_unreach_nlri_partial {
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uint16_t afi; /* sa_family_t */
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uint8_t safi;
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} __attribute__ ((packed));
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/* we use it as an extended attribute */
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#define BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE (4 + sizeof(struct bgp_attr_mp_unreach_nlri_partial))
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/* bgp_path_attr.flags (bitfields) */
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#define BGP_PATH_ATTR_FLAG_OPTIONAL (1 << 7)
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#define BGP_PATH_ATTR_FLAG_TRANS (1 << 6)
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@ -121,9 +137,11 @@ struct bgp_path_attr {
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#define BGP_PATH_ATTR_CODE_ATOMIC_AGGREGATE 6 /* well-known, discretionary */
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#define BGP_PATH_ATTR_CODE_AGGREGATOR 7 /* optional, transitive */
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#define BGP_PATH_ATTR_CODE_COMMUNITIES 8 /* optional, transitive (RFC1997) */
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#define BGP_PATH_ATTR_CODE_MP_REACH_NLRI 14 /* optional, non-transitive (RFC4760) */
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#define BGP_PATH_ATTR_CODE_MP_UNREACH_NLRI 15 /* optional, non-transitive (RFC4760) */
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#define BGP_PATH_ATTR_SIZE(p) ((((p).flags & BGP_PATH_ATTR_FLAG_EXTLEN) \
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? ((p).data.e.len + 1) : (p).data.s.len) + 3)
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? ((p).data.e.len + 4) : (p).data.s.len) + 3)
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/* well known COMMUNITIES */
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#define BGP_COMMUNITY_NO_EXPORT 0xffffff01 /* don't advertise outside confederation */
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@ -222,6 +240,8 @@ struct bgp_peer {
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int handle_ipv6_routes; /* can handle IPv6 routes advertisements */
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int update_routes6; /* UPDATE required for IPv6 routes */
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struct bgp_route6_list *routes6; /* IPv6 routes known by this peer */
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char mp_reach_nlri_partial[BGP_PATH_ATTR_MP_REACH_NLRI_PARTIAL_SIZE];
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char mp_unreach_nlri_partial[BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE];
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};
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/* bgp_peer.cli_flag */
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