From: Daniel Walton <[email protected]> Allow the replacement of a specific AS with another.
Signed-off-by: Daniel Walton <[email protected]> --- bgpd/bgp_aspath.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++ bgpd/bgp_aspath.h | 2 ++ bgpd/bgp_route.c | 15 +++++++++++++++ bgpd/bgp_vty.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ bgpd/bgpd.c | 11 +++++++++++ bgpd/bgpd.h | 4 +++- 6 files changed, 129 insertions(+), 1 deletion(-) diff --git a/bgpd/bgp_aspath.c b/bgpd/bgp_aspath.c index 776f6e6..aace91b 100644 --- a/bgpd/bgp_aspath.c +++ b/bgpd/bgp_aspath.c @@ -1167,6 +1167,58 @@ aspath_private_as_check (struct aspath *aspath) return 1; } +/* Return True if the entire ASPATH consist of the specified ASN */ +int +aspath_single_asn_check (struct aspath *aspath, as_t asn) +{ + struct assegment *seg; + + if ( !(aspath && aspath->segments) ) + return 0; + + seg = aspath->segments; + + while (seg) + { + int i; + + for (i = 0; i < seg->length; i++) + { + if (seg->as[i] != asn) + return 0; + } + seg = seg->next; + } + return 1; +} + +/* Replace all instances of the target ASN with our own ASN */ +struct aspath * +aspath_replace_specific_asn (struct aspath *aspath, as_t target_asn, + as_t our_asn) +{ + struct aspath *new; + struct assegment *seg; + + new = aspath_dup(aspath); + seg = new->segments; + + while (seg) + { + int i; + + for (i = 0; i < seg->length; i++) + { + if (seg->as[i] == target_asn) + seg->as[i] = our_asn; + } + seg = seg->next; + } + + aspath_str_update(new); + return new; +} + /* Replace all private ASNs with our own ASN */ struct aspath * aspath_replace_private_asns (struct aspath *aspath, as_t asn) diff --git a/bgpd/bgp_aspath.h b/bgpd/bgp_aspath.h index 7280f31..134f1f6 100644 --- a/bgpd/bgp_aspath.h +++ b/bgpd/bgp_aspath.h @@ -98,6 +98,8 @@ extern void aspath_print_all_vty (struct vty *); extern unsigned int aspath_key_make (void *); extern int aspath_loop_check (struct aspath *, as_t); extern int aspath_private_as_check (struct aspath *); +extern int aspath_single_asn_check (struct aspath *, as_t asn); +extern struct aspath *aspath_replace_specific_asn (struct aspath *aspath, as_t target_asn, as_t our_asn); extern struct aspath *aspath_replace_private_asns(struct aspath *aspath, as_t asn); extern struct aspath *aspath_remove_private_asns (struct aspath *aspath); extern int aspath_firstas_check (struct aspath *, as_t); diff --git a/bgpd/bgp_route.c b/bgpd/bgp_route.c index f48cfed..ab81b72 100644 --- a/bgpd/bgp_route.c +++ b/bgpd/bgp_route.c @@ -915,6 +915,19 @@ bgp_peer_remove_private_as(struct bgp *bgp, afi_t afi, safi_t safi, } } +/* If this is an EBGP peer with as-override */ +static void +bgp_peer_as_override(struct bgp *bgp, afi_t afi, safi_t safi, + struct peer *peer, struct attr *attr) +{ + if (peer->sort == BGP_PEER_EBGP && + peer_af_flag_check (peer, afi, safi, PEER_FLAG_AS_OVERRIDE)) + { + if (aspath_single_asn_check (attr->aspath, peer->as)) + attr->aspath = aspath_replace_specific_asn (attr->aspath, peer->as, bgp->as); + } +} + static int bgp_announce_check (struct bgp_info *ri, struct peer *peer, struct prefix *p, struct attr *attr, afi_t afi, safi_t safi) @@ -1177,6 +1190,7 @@ bgp_announce_check (struct bgp_info *ri, struct peer *peer, struct prefix *p, #endif /* HAVE_IPV6 */ bgp_peer_remove_private_as(bgp, afi, safi, peer, attr); + bgp_peer_as_override(bgp, afi, safi, peer, attr); /* Route map & unsuppress-map apply. */ if (ROUTE_MAP_OUT_NAME (filter) @@ -1384,6 +1398,7 @@ bgp_announce_check_rsclient (struct bgp_info *ri, struct peer *rsclient, #endif /* HAVE_IPV6 */ bgp_peer_remove_private_as(bgp, afi, safi, rsclient, attr); + bgp_peer_as_override(bgp, afi, safi, rsclient, attr); /* Route map & unsuppress-map apply. */ if (ROUTE_MAP_OUT_NAME (filter) || (ri->extra && ri->extra->suppress) ) diff --git a/bgpd/bgp_vty.c b/bgpd/bgp_vty.c index bdc149a..7bec815 100644 --- a/bgpd/bgp_vty.c +++ b/bgpd/bgp_vty.c @@ -232,6 +232,9 @@ bgp_vty_return (struct vty *vty, int ret) case BGP_ERR_NO_IBGP_WITH_TTLHACK: str = "ttl-security only allowed for EBGP peers"; break; + case BGP_ERR_AS_OVERRIDE: + str = "as-override cannot be configured for IBGP peers"; + break; } if (str) { @@ -2636,6 +2639,32 @@ DEFUN (no_neighbor_nexthop_self, PEER_FLAG_NEXTHOP_SELF|PEER_FLAG_NEXTHOP_SELF_ALL); } +/* neighbor as-override */ +DEFUN (neighbor_as_override, + neighbor_as_override_cmd, + NEIGHBOR_CMD2 "as-override", + NEIGHBOR_STR + NEIGHBOR_ADDR_STR2 + "Override ASNs in outbound updates if aspath equals remote-as\n") +{ + return peer_af_flag_set_vty (vty, argv[0], bgp_node_afi (vty), + bgp_node_safi (vty), + PEER_FLAG_AS_OVERRIDE); +} + +DEFUN (no_neighbor_as_override, + no_neighbor_as_override_cmd, + NO_NEIGHBOR_CMD2 "as-override", + NO_STR + NEIGHBOR_STR + NEIGHBOR_ADDR_STR2 + "Override ASNs in outbound updates if aspath equals remote-as\n") +{ + return peer_af_flag_unset_vty (vty, argv[0], bgp_node_afi (vty), + bgp_node_safi (vty), + PEER_FLAG_AS_OVERRIDE); +} + /* neighbor remove-private-AS. */ DEFUN (neighbor_remove_private_as, neighbor_remove_private_as_cmd, @@ -8256,6 +8285,9 @@ bgp_show_peer_afi (struct vty *vty, struct peer *p, afi_t afi, safi_t safi) else if (CHECK_FLAG (p->af_flags[afi][safi], PEER_FLAG_REMOVE_PRIVATE_AS)) vty_out (vty, " Private AS numbers removed in updates to this neighbor%s", VTY_NEWLINE); + if (CHECK_FLAG (p->af_flags[afi][safi], PEER_FLAG_AS_OVERRIDE)) + vty_out (vty, " Override ASNs in outbound updates if aspath equals remote-as%s", VTY_NEWLINE); + if (CHECK_FLAG (p->af_flags[afi][safi], PEER_FLAG_NEXTHOP_SELF) || CHECK_FLAG (p->af_flags[afi][safi], PEER_FLAG_NEXTHOP_SELF_ALL)) vty_out (vty, " NEXT_HOP is always this router%s", VTY_NEWLINE); @@ -10331,6 +10363,20 @@ bgp_vty_init (void) install_element (BGP_VPNV4_NODE, &neighbor_nexthop_self_cmd); install_element (BGP_VPNV4_NODE, &no_neighbor_nexthop_self_cmd); + /* "neighbor as-override" commands. */ + install_element (BGP_NODE, &neighbor_as_override_cmd); + install_element (BGP_NODE, &no_neighbor_as_override_cmd); + install_element (BGP_IPV4_NODE, &neighbor_as_override_cmd); + install_element (BGP_IPV4_NODE, &no_neighbor_as_override_cmd); + install_element (BGP_IPV4M_NODE, &neighbor_as_override_cmd); + install_element (BGP_IPV4M_NODE, &no_neighbor_as_override_cmd); + install_element (BGP_IPV6_NODE, &neighbor_as_override_cmd); + install_element (BGP_IPV6_NODE, &no_neighbor_as_override_cmd); + install_element (BGP_IPV6M_NODE, &neighbor_as_override_cmd); + install_element (BGP_IPV6M_NODE, &no_neighbor_as_override_cmd); + install_element (BGP_VPNV4_NODE, &neighbor_as_override_cmd); + install_element (BGP_VPNV4_NODE, &no_neighbor_as_override_cmd); + /* "neighbor remove-private-AS" commands. */ install_element (BGP_NODE, &neighbor_remove_private_as_cmd); install_element (BGP_NODE, &no_neighbor_remove_private_as_cmd); diff --git a/bgpd/bgpd.c b/bgpd/bgpd.c index cc2abb5..78f9a2c 100644 --- a/bgpd/bgpd.c +++ b/bgpd/bgpd.c @@ -2713,6 +2713,7 @@ static const struct peer_flag_action peer_af_flag_action_list[] = { PEER_FLAG_ORF_PREFIX_RM, 1, peer_change_reset }, { PEER_FLAG_NEXTHOP_LOCAL_UNCHANGED, 0, peer_change_reset_out }, { PEER_FLAG_NEXTHOP_SELF_ALL, 1, peer_change_reset_out }, + { PEER_FLAG_AS_OVERRIDE, 1, peer_change_reset_out }, { 0, 0, 0 } }; @@ -2956,6 +2957,11 @@ peer_af_flag_modify (struct peer *peer, afi_t afi, safi_t safi, u_int32_t flag, && peer_sort (peer) == BGP_PEER_IBGP) return BGP_ERR_REMOVE_PRIVATE_AS; + /* as-override is not allowed for IBGP peers */ + if (flag & PEER_FLAG_AS_OVERRIDE + && peer_sort (peer) == BGP_PEER_IBGP) + return BGP_ERR_AS_OVERRIDE; + /* When unset the peer-group member's flag we have to check peer-group configuration. */ if (! set && peer->af_group[afi][safi]) @@ -5523,6 +5529,11 @@ bgp_config_write_peer (struct vty *vty, struct bgp *bgp, vty_out (vty, " neighbor %s remove-private-AS%s", addr, VTY_NEWLINE); } + /* as-override */ + if (peer_af_flag_check (peer, afi, safi, PEER_FLAG_AS_OVERRIDE) && + !peer->af_group[afi][safi]) + vty_out (vty, " neighbor %s as-override%s", addr, VTY_NEWLINE); + /* send-community print. */ if (! peer->af_group[afi][safi]) { diff --git a/bgpd/bgpd.h b/bgpd/bgpd.h index ec73ae1..afe2b50 100644 --- a/bgpd/bgpd.h +++ b/bgpd/bgpd.h @@ -489,6 +489,7 @@ struct peer #define PEER_FLAG_NEXTHOP_SELF_ALL (1 << 17) /* next-hop-self all */ #define PEER_FLAG_REMOVE_PRIVATE_AS_ALL (1 << 18) /* remove-private-as all */ #define PEER_FLAG_REMOVE_PRIVATE_AS_REPLACE (1 << 19) /* remove-private-as replace-as */ +#define PEER_FLAG_AS_OVERRIDE (1 << 20) /* as-override */ /* MD5 password */ char *password; @@ -907,7 +908,8 @@ enum bgp_clear_type #define BGP_ERR_NO_IBGP_WITH_TTLHACK -31 #define BGP_ERR_NO_INTERFACE_CONFIG -32 #define BGP_ERR_CANNOT_HAVE_LOCAL_AS_SAME_AS_REMOTE_AS -33 -#define BGP_ERR_MAX -34 +#define BGP_ERR_AS_OVERRIDE -34 +#define BGP_ERR_MAX -35 extern struct bgp_master *bm; 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