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Implements proper multihop BGP.

Browse source 
Also does some incompatible changes to config file syntax,
like removing 'via IP' from multihop option.
This commit is contained in:
Ondrej Zajicek 2010-07-12 17:39:39 +02:00
parent cfe34a316e
commit 9be9a26413
7 changed files with 80 additions and 52 deletions
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46
doc/bird.sgml
View file

@ -272,7 +272,7 @@ protocol rip {
listen to IPv6 connections only. This is needed if you want to
run both bird and bird6 on the same port.
<tag>timeformat route|protocol|base|log "<m/format1/" [<m/limit> "<m/format2/"]</tag>
<tag>timeformat route|protocol|base|log "<m/format1/" [<m/limit/ "<m/format2/"]</tag>
This option allows to specify a format of date/time used by
BIRD. The first argument specifies for which purpose such
format is used. <cf/route/ is a format used in 'show route'
@ -280,8 +280,8 @@ protocol rip {
command output, <cf/base/ is used for other commands and
<cf/log/ is used in a log file.
"<m/format1/" is a format string using <i/strftime(3)/
notation (see <i/man strftime/ for details). <m/limit> and
"<m/format1/" is a format string using <it/strftime(3)/
notation (see <it/man strftime/ for details). <m/limit> and
"<m/format2/" allow to specify the second format string for
times in past deeper than <m/limit/ seconds. There are two
shorthands: <cf/iso long/ is a ISO 8601 date/time format
@ -976,10 +976,13 @@ This allows to set routing policy and all the other parameters differently
for each neighbor using the following configuration parameters:
<descrip>
<tag>local as <m/number/</tag> Define which AS we are part of. (Note that
contrary to other IP routers, BIRD is able to act as a router located
in multiple AS'es simultaneously, but in such cases you need to tweak
the BGP paths manually in the filters to get consistent behavior.)
<tag>local <m/[ip]/] as <m/number/</tag> Define which AS we
are part of. (Note that contrary to other IP routers, BIRD is
able to act as a router located in multiple AS'es
simultaneously, but in such cases you need to tweak the BGP
paths manually in the filters to get consistent behavior.)
Optional <cf/ip/ argument specifies a source address,
equivalent to the <cf/source address/ option (see below).
This parameter is mandatory.
<tag>neighbor <m/ip/ as <m/number/</tag> Define neighboring router
@ -988,16 +991,27 @@ for each neighbor using the following configuration parameters:
of your router's interfaces. In case the neighbor is in the same AS
as we are, we automatically switch to iBGP. This parameter is mandatory.
<tag>multihop <m/number/ via <m/ip/</tag> Configure multihop BGP to a
neighbor which is connected at most <m/number/ hops far and to which
we should route via our direct neighbor with address <m/ip/.
<tag>multihop <m/[number]/]</tag> Configure multihop BGP
session to a neighbor that isn't directly connected.
Accurately, this option should be used if the configured
neighbor IP address does not match with any local network
subnets. Such IP address have to be reachable through system
routing table. For multihop BGP it is recommended to
explicitly configure <cf/source address/ to have it
stable. Optional <cf/number/ argument can be used to limit TTL
(the number of hops).
Default: switched off.
<tag>source address <m/ip/</tag> Define local address we
should use for next hop calculation and as a source address
for the BGP session. Default: the address of the local
end of the interface our neighbor is connected to.
<tag>next hop self</tag> Avoid calculation of the Next Hop
attribute and always advertise our own source address (see
below) as a next hop. This needs to be used only occasionally
to circumvent misconfigurations of other routers.
Default: disabled.
attribute and always advertise our own source address as a
next hop. This needs to be used only occasionally to
circumvent misconfigurations of other routers. Default:
disabled.
<tag>missing lladdr self|drop|ignore</tag>Next Hop attribute
in BGP-IPv6 sometimes contains just the global IPv6 address,
@ -1015,10 +1029,6 @@ for each neighbor using the following configuration parameters:
that case default is <cf/drop/, because route servers usually
does not forward packets ifselves.
<tag>source address <m/ip/</tag> Define local address we should use
for next hop calculation. Default: the address of the local end
of the interface our neighbor is connected to.
<tag>password <m/string/</tag> Use this password for MD5 authentication
of BGP sessions. Default: no authentication. Password has to be set by
external utility (e.g. setkey(8)) on BSD systems.

14
proto/bgp/attrs.c
View file

@ -752,7 +752,7 @@ bgp_get_bucket(struct bgp_proto *p, net *n, ea_list *attrs, int originate)
/* Check if next hop is valid */
a = ea_find(new, EA_CODE(EAP_BGP, BA_NEXT_HOP));
if (!a || ipa_equal(p->next_hop, *(ip_addr *)a->u.ptr->data))
if (!a || ipa_equal(p->cf->remote_ip, *(ip_addr *)a->u.ptr->data))
{
log(L_ERR "%s: Invalid NEXT_HOP attribute in route %I/%d", p->p.name, n->n.prefix, n->n.pxlen);
return NULL;
@ -808,7 +808,6 @@ bgp_rt_notify(struct proto *P, rtable *tbl UNUSED, net *n, rte *new, rte *old UN
bgp_schedule_packet(p->conn, PKT_UPDATE);
}
static int
bgp_create_attrs(struct bgp_proto *p, rte *e, ea_list **attrs, struct linpool *pool)
{
@ -834,12 +833,14 @@ bgp_create_attrs(struct bgp_proto *p, rte *e, ea_list **attrs, struct linpool *p
put_u32(z+2, p->local_as);
}
/* iBGP -> use gw, eBGP multi-hop -> use source_addr,
eBGP single-hop -> use gw if on the same iface */
z = bgp_set_attr_wa(ea->attrs+2, pool, BA_NEXT_HOP, NEXT_HOP_LENGTH);
if (p->cf->next_hop_self ||
rta->dest != RTD_ROUTER ||
ipa_equal(e->attrs->gw, IPA_NONE) ||
ipa_equal(rta->gw, IPA_NONE) ||
ipa_has_link_scope(rta->gw) ||
(!p->is_internal && (rta->iface != p->neigh->iface)))
(!p->is_internal && (!p->neigh || (rta->iface != p->neigh->iface))))
set_next_hop(z, p->source_addr);
else
set_next_hop(z, rta->gw);
@ -904,8 +905,11 @@ bgp_update_attrs(struct bgp_proto *p, rte *e, ea_list **attrs, struct linpool *p
bgp_attach_attr(attrs, pool, BA_MULTI_EXIT_DISC, 0);
}
/* iBGP -> keep next_hop, eBGP multi-hop -> use source_addr,
eBGP single-hop -> keep next_hop if on the same iface */
a = ea_find(e->attrs->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP));
if (a && !p->cf->next_hop_self && (p->is_internal || (!p->is_internal && e->attrs->iface == p->neigh->iface)))
if (a && !p->cf->next_hop_self &&
(p->is_internal || (p->neigh && (e->attrs->iface == p->neigh->iface))))
{
/* Leave the original next hop attribute, will check later where does it point */
}

50
proto/bgp/bgp.c
View file

@ -145,6 +145,10 @@ bgp_startup_timeout(timer *t)
static void
bgp_initiate(struct bgp_proto *p)
{
int rv = bgp_open(p);
if (rv < 0)
return;
if (p->startup_delay)
{
BGP_TRACE(D_EVENTS, "Startup delayed by %d seconds", p->startup_delay);
@ -347,6 +351,10 @@ bgp_conn_enter_established_state(struct bgp_conn *conn)
BGP_TRACE(D_EVENTS, "BGP session established");
DBG("BGP: UP!!!\n");
/* For multi-hop BGP sessions */
if (ipa_zero(p->source_addr))
p->source_addr = conn->sk->saddr;
p->conn = conn;
p->last_error_class = 0;
p->last_error_code = 0;
@ -669,10 +677,11 @@ bgp_setup_listen_sk(ip_addr addr, unsigned port, u32 flags)
static void
bgp_start_neighbor(struct bgp_proto *p)
{
p->local_addr = p->neigh->iface->addr->ip;
p->source_addr = ipa_nonzero(p->cf->source_addr) ? p->cf->source_addr : p->local_addr;
/* Called only for single-hop BGP sessions */
if (ipa_zero(p->source_addr))
p->source_addr = p->neigh->iface->addr->ip;
DBG("BGP: local=%I remote=%I\n", p->source_addr, p->next_hop);
#ifdef IPV6
{
struct ifa *a;
@ -691,10 +700,6 @@ bgp_start_neighbor(struct bgp_proto *p)
}
#endif
int rv = bgp_open(p);
if (rv < 0)
return;
bgp_initiate(p);
}
@ -742,25 +747,22 @@ bgp_start_locked(struct object_lock *lock)
if (p->p.proto_state != PS_START)
{
DBG("BGP: Got lock in different state %d\n", p->p.proto_state);
return;
return;
}
DBG("BGP: Got lock\n");
p->local_id = proto_get_router_id(&cf->c);
p->next_hop = cf->multihop ? cf->multihop_via : cf->remote_ip;
p->neigh = neigh_find(&p->p, &p->next_hop, NEF_STICKY);
if (cf->rr_client)
if (cf->multihop)
{
p->rr_cluster_id = cf->rr_cluster_id ? cf->rr_cluster_id : p->local_id;
p->rr_client = cf->rr_client;
/* Multi-hop sessions do not use neighbor entries */
bgp_initiate(p);
return;
}
p->rs_client = cf->rs_client;
if (!p->neigh)
p->neigh = neigh_find(&p->p, &cf->remote_ip, NEF_STICKY);
if (!p->neigh || (p->neigh->scope == SCOPE_HOST))
{
log(L_ERR "%s: Invalid next hop %I", p->p.name, p->next_hop);
log(L_ERR "%s: Invalid remote address %I", p->p.name, cf->remote_ip);
/* As we do not start yet, we can just disable protocol */
p->p.disabled = 1;
bgp_store_error(p, NULL, BE_MISC, BEM_INVALID_NEXT_HOP);
@ -771,7 +773,7 @@ bgp_start_locked(struct object_lock *lock)
if (p->neigh->iface)
bgp_start_neighbor(p);
else
BGP_TRACE(D_EVENTS, "Waiting for %I to become my neighbor", p->next_hop);
BGP_TRACE(D_EVENTS, "Waiting for %I to become my neighbor", cf->remote_ip);
}
static int
@ -796,6 +798,9 @@ bgp_start(struct proto *P)
p->startup_timer->hook = bgp_startup_timeout;
p->startup_timer->data = p;
p->remote_id = 0;
p->source_addr = p->cf->source_addr;
/*
* Before attempting to create the connection, we need to lock the
* port, so that are sure we're the only instance attempting to talk
@ -869,7 +874,13 @@ bgp_init(struct proto_config *C)
p->local_as = c->local_as;
p->remote_as = c->remote_as;
p->is_internal = (c->local_as == c->remote_as);
p->local_id = proto_get_router_id(C);
p->rs_client = c->rs_client;
p->rr_client = c->rr_client;
if (p->rr_client)
p->rr_cluster_id = c->rr_cluster_id ? c->rr_cluster_id : p->local_id;
p->igp_table = get_igp_table(c);
return P;
}
@ -1046,7 +1057,6 @@ bgp_show_proto_info(struct proto *P)
cli_msg(-1006, " Neighbor AS: %u", p->remote_as);
cli_msg(-1006, " Neighbor ID: %R", p->remote_id);
cli_msg(-1006, " Neighbor address: %I", p->cf->remote_ip);
cli_msg(-1006, " Nexthop address: %I", p->next_hop);
cli_msg(-1006, " Source address: %I", p->source_addr);
cli_msg(-1006, " Neighbor caps: %s%s",
c->peer_refresh_support ? " refresh" : "",

9
proto/bgp/bgp.h
View file

@ -20,7 +20,6 @@ struct bgp_config {
u32 local_as, remote_as;
ip_addr remote_ip;
int multihop; /* Number of hops if multihop */
ip_addr multihop_via; /* Multihop: address to route to */
ip_addr source_addr; /* Source address to use */
int next_hop_self; /* Always set next hop to local IP address */
int missing_lladdr; /* What we will do when we don' know link-local addr, see MLL_* */
@ -89,10 +88,8 @@ struct bgp_proto {
struct bgp_conn outgoing_conn; /* Outgoing connection we're working with */
struct bgp_conn incoming_conn; /* Incoming connection we have neither accepted nor rejected yet */
struct object_lock *lock; /* Lock for neighbor connection */
ip_addr next_hop; /* Either the peer or multihop_via */
struct neighbor *neigh; /* Neighbor entry corresponding to next_hop */
ip_addr local_addr; /* Address of the local end of the link to next_hop */
ip_addr source_addr; /* Address used as advertised next hop, usually local_addr */
struct neighbor *neigh; /* Neighbor entry corresponding to remote ip, NULL if multihop */
ip_addr source_addr; /* Local address used as an advertised next hop */
rtable *igp_table; /* Table used for recursive next hop lookups */
struct event *event; /* Event for respawning and shutting process */
struct timer *startup_timer; /* Timer used to delay protocol startup due to previous errors (startup_delay) */
@ -109,7 +106,7 @@ struct bgp_proto {
#ifdef IPV6
byte *mp_reach_start, *mp_unreach_start; /* Multiprotocol BGP attribute notes */
unsigned mp_reach_len, mp_unreach_len;
ip_addr local_link; /* Link-level version of local_addr */
ip_addr local_link; /* Link-level version of source_addr */
#endif
};

4
proto/bgp/config.Y
View file

@ -54,6 +54,7 @@ bgp_proto:
bgp_proto_start proto_name '{'
| bgp_proto proto_item ';'
| bgp_proto LOCAL AS expr ';' { BGP_CFG->local_as = $4; }
| bgp_proto LOCAL ipa AS expr ';' { BGP_CFG->source_addr = $3; BGP_CFG->local_as = $5; }
| bgp_proto NEIGHBOR ipa AS expr ';' {
if (ipa_nonzero(BGP_CFG->remote_ip)) cf_error("Only one neighbor per BGP instance is allowed");
@ -67,7 +68,8 @@ bgp_proto:
| bgp_proto STARTUP HOLD TIME expr ';' { BGP_CFG->initial_hold_time = $5; }
| bgp_proto CONNECT RETRY TIME expr ';' { BGP_CFG->connect_retry_time = $5; }
| bgp_proto KEEPALIVE TIME expr ';' { BGP_CFG->keepalive_time = $4; }
| bgp_proto MULTIHOP expr VIA ipa ';' { BGP_CFG->multihop = $3; BGP_CFG->multihop_via = $5; }
| bgp_proto MULTIHOP ';' { BGP_CFG->multihop = 64; }
| bgp_proto MULTIHOP expr ';' { BGP_CFG->multihop = $3; }
| bgp_proto NEXT HOP SELF ';' { BGP_CFG->next_hop_self = 1; }
| bgp_proto MISSING LLADDR SELF ';' { BGP_CFG->missing_lladdr = MLL_SELF; }
| bgp_proto MISSING LLADDR DROP ';' { BGP_CFG->missing_lladdr = MLL_DROP; }

4
proto/bgp/packets.c
View file

@ -58,7 +58,7 @@ mrt_put_bgp4_hdr(byte *buf, struct bgp_conn *conn, int as4)
buf+=4;
}
put_u16(buf+0, p->neigh->iface->index);
put_u16(buf+0, p->neigh ? p->neigh->iface->index : 0);
put_u16(buf+2, BGP_AF);
buf+=4;
buf = ipa_put_addr(buf, conn->sk ? conn->sk->daddr : IPA_NONE);
@ -402,7 +402,7 @@ bgp_create_update(struct bgp_conn *conn, byte *buf)
*/
n = neigh_find(&p->p, &ip, 0);
if (n && n->iface == p->neigh->iface)
if (n && p->neigh && n->iface == p->neigh->iface)
{
if (second && ipa_nonzero(ipp[1]))
ip_ll = ipp[1];

5
sysdep/unix/io.c
View file

@ -1004,6 +1004,11 @@ sk_leave_group(sock *s, ip_addr maddr)
static void
sk_tcp_connected(sock *s)
{
sockaddr lsa;
int lsa_len = sizeof(lsa);
if (getsockname(s->fd, (struct sockaddr *) &lsa, &lsa_len) == 0)
get_sockaddr(&lsa, &s->saddr, &s->sport, 1);
s->type = SK_TCP;
sk_alloc_bufs(s);
s->tx_hook(s);