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bird/proto/bgp/bgp.c

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/*
* BIRD -- The Border Gateway Protocol
*
* (c) 2000 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
/**
* DOC: Border Gateway Protocol
*
* The BGP protocol is implemented in three parts: |bgp.c| which takes care of the
* connection and most of the interface with BIRD core, |packets.c| handling
* both incoming and outgoing BGP packets and |attrs.c| containing functions for
* manipulation with BGP attribute lists.
*
* As opposed to the other existing routing daemons, BIRD has a sophisticated core
* architecture which is able to keep all the information needed by BGP in the
* primary routing table, therefore no complex data structures like a central
* BGP table are needed. This increases memory footprint of a BGP router with
* many connections, but not too much and, which is more important, it makes
* BGP much easier to implement.
*
* Each instance of BGP (corresponding to a single BGP peer) is described by a &bgp_proto
* structure to which are attached individual connections represented by &bgp_connection
* (usually, there exists only one connection, but during BGP session setup, there
* can be more of them). The connections are handled according to the BGP state machine
* defined in the RFC with all the timers and all the parameters configurable.
*
* In incoming direction, we listen on the connection's socket and each time we receive
* some input, we pass it to bgp_rx(). It decodes packet headers and the markers and
* passes complete packets to bgp_rx_packet() which distributes the packet according
* to its type.
*
* In outgoing direction, we gather all the routing updates and sort them to buckets
* (&bgp_bucket) according to their attributes (we keep a hash table for fast comparison
* of &rta's and a &fib which helps us to find if we already have another route for
* the same destination queued for sending, so that we can replace it with the new one
* immediately instead of sending both updates). There also exists a special bucket holding
* all the route withdrawals which cannot be queued anywhere else as they don't have any
* attributes. If we have any packet to send (due to either new routes or the connection
* tracking code wanting to send a Open, Keepalive or Notification message), we call
* bgp_schedule_packet() which sets the corresponding bit in a @packet_to_send
* bit field in &bgp_conn and as soon as the transmit socket buffer becomes empty,
* we call bgp_fire_tx(). It inspects state of all the packet type bits and calls
* the corresponding bgp_create_xx() functions, eventually rescheduling the same packet
* type if we have more data of the same type to send.
*
* The processing of attributes consists of two functions: bgp_decode_attrs() for checking
* of the attribute blocks and translating them to the language of BIRD's extended attributes
* and bgp_encode_attrs() which does the converse. Both functions are built around a
* @bgp_attr_table array describing all important characteristics of all known attributes.
* Unknown transitive attributes are attached to the route as %EAF_TYPE_OPAQUE byte streams.
*
* BGP protocol implements graceful restart in both restarting (local restart)
* and receiving (neighbor restart) roles. The first is handled mostly by the
* graceful restart code in the nest, BGP protocol just handles capabilities,
* sets @gr_wait and locks graceful restart until end-of-RIB mark is received.
* The second is implemented by internal restart of the BGP state to %BS_IDLE
* and protocol state to %PS_START, but keeping the protocol up from the core
* point of view and therefore maintaining received routes. Routing table
* refresh cycle (rt_refresh_begin(), rt_refresh_end()) is used for removing
* stale routes after reestablishment of BGP session during graceful restart.
*/
#undef LOCAL_DEBUG
#include "nest/bird.h"
#include "nest/iface.h"
#include "nest/protocol.h"
#include "nest/route.h"
#include "nest/cli.h"
#include "nest/locks.h"
#include "conf/conf.h"
#include "lib/socket.h"
#include "lib/resource.h"
#include "lib/string.h"
#include "bgp.h"
struct linpool *bgp_linpool; /* Global temporary pool */
static sock *bgp_listen_sk; /* Global listening socket */
static int bgp_counter; /* Number of protocol instances using the listening socket */
static void bgp_close(struct bgp_proto *p, int apply_md5);
static void bgp_connect(struct bgp_proto *p);
static void bgp_active(struct bgp_proto *p);
static sock *bgp_setup_listen_sk(ip_addr addr, unsigned port, u32 flags);
static void bgp_update_bfd(struct bgp_proto *p, int use_bfd);
/**
* bgp_open - open a BGP instance
* @p: BGP instance
*
* This function allocates and configures shared BGP resources.
* Should be called as the last step during initialization
* (when lock is acquired and neighbor is ready).
* When error, state changed to PS_DOWN, -1 is returned and caller
* should return immediately.
*/
static int
bgp_open(struct bgp_proto *p)
{
struct config *cfg = p->cf->c.global;
int errcode;
bgp_counter++;
if (!bgp_listen_sk)
bgp_listen_sk = bgp_setup_listen_sk(cfg->listen_bgp_addr, cfg->listen_bgp_port, cfg->listen_bgp_flags);
if (!bgp_listen_sk)
{
bgp_counter--;
errcode = BEM_NO_SOCKET;
goto err;
}
if (!bgp_linpool)
bgp_linpool = lp_new(&root_pool, 4080);
if (p->cf->password)
{
int rv = sk_set_md5_auth(bgp_listen_sk, p->cf->remote_ip, p->cf->iface, p->cf->password);
if (rv < 0)
{
bgp_close(p, 0);
errcode = BEM_INVALID_MD5;
goto err;
}
}
return 0;
err:
p->p.disabled = 1;
bgp_store_error(p, NULL, BE_MISC, errcode);
proto_notify_state(&p->p, PS_DOWN);
return -1;
}
static void
bgp_startup(struct bgp_proto *p)
{
BGP_TRACE(D_EVENTS, "Started");
p->start_state = p->cf->capabilities ? BSS_CONNECT : BSS_CONNECT_NOCAP;
if (!p->cf->passive)
bgp_active(p);
}
static void
bgp_startup_timeout(timer *t)
{
bgp_startup(t->data);
}
static void
bgp_initiate(struct bgp_proto *p)
{
int rv = bgp_open(p);
if (rv < 0)
return;
if (p->cf->bfd)
bgp_update_bfd(p, p->cf->bfd);
if (p->startup_delay)
{
p->start_state = BSS_DELAY;
BGP_TRACE(D_EVENTS, "Startup delayed by %d seconds", p->startup_delay);
bgp_start_timer(p->startup_timer, p->startup_delay);
}
else
bgp_startup(p);
}
/**
* bgp_close - close a BGP instance
* @p: BGP instance
* @apply_md5: 0 to disable unsetting MD5 auth
*
* This function frees and deconfigures shared BGP resources.
* @apply_md5 is set to 0 when bgp_close is called as a cleanup
* from failed bgp_open().
*/
static void
bgp_close(struct bgp_proto *p, int apply_md5)
{
ASSERT(bgp_counter);
bgp_counter--;
if (p->cf->password && apply_md5)
sk_set_md5_auth(bgp_listen_sk, p->cf->remote_ip, p->cf->iface, NULL);
if (!bgp_counter)
{
rfree(bgp_listen_sk);
bgp_listen_sk = NULL;
rfree(bgp_linpool);
bgp_linpool = NULL;
}
}
/**
* bgp_start_timer - start a BGP timer
* @t: timer
* @value: time to fire (0 to disable the timer)
*
* This functions calls tm_start() on @t with time @value and the
* amount of randomization suggested by the BGP standard. Please use
* it for all BGP timers.
*/
void
bgp_start_timer(timer *t, int value)
{
if (value)
{
/* The randomization procedure is specified in RFC 1771: 9.2.3.3 */
t->randomize = value / 4;
tm_start(t, value - t->randomize);
}
else
tm_stop(t);
}
/**
* bgp_close_conn - close a BGP connection
* @conn: connection to close
*
* This function takes a connection described by the &bgp_conn structure,
* closes its socket and frees all resources associated with it.
*/
void
bgp_close_conn(struct bgp_conn *conn)
{
// struct bgp_proto *p = conn->bgp;
DBG("BGP: Closing connection\n");
conn->packets_to_send = 0;
rfree(conn->connect_retry_timer);
conn->connect_retry_timer = NULL;
rfree(conn->keepalive_timer);
conn->keepalive_timer = NULL;
rfree(conn->hold_timer);
conn->hold_timer = NULL;
rfree(conn->sk);
conn->sk = NULL;
rfree(conn->tx_ev);
conn->tx_ev = NULL;
}
/**
* bgp_update_startup_delay - update a startup delay
* @p: BGP instance
*
* This function updates a startup delay that is used to postpone next BGP connect.
* It also handles disable_after_error and might stop BGP instance when error
* happened and disable_after_error is on.
*
* It should be called when BGP protocol error happened.
*/
void
bgp_update_startup_delay(struct bgp_proto *p)
{
struct bgp_config *cf = p->cf;
DBG("BGP: Updating startup delay\n");
if (p->last_proto_error && ((now - p->last_proto_error) >= (int) cf->error_amnesia_time))
p->startup_delay = 0;
p->last_proto_error = now;
if (cf->disable_after_error)
{
p->startup_delay = 0;
p->p.disabled = 1;
return;
}
if (!p->startup_delay)
p->startup_delay = cf->error_delay_time_min;
else
p->startup_delay = MIN(2 * p->startup_delay, cf->error_delay_time_max);
}
static void
bgp_graceful_close_conn(struct bgp_conn *conn, unsigned subcode)
{
switch (conn->state)
{
case BS_IDLE:
case BS_CLOSE:
return;
case BS_CONNECT:
case BS_ACTIVE:
bgp_conn_enter_idle_state(conn);
return;
case BS_OPENSENT:
case BS_OPENCONFIRM:
case BS_ESTABLISHED:
bgp_error(conn, 6, subcode, NULL, 0);
return;
default:
bug("bgp_graceful_close_conn: Unknown state %d", conn->state);
}
}
static void
bgp_down(struct bgp_proto *p)
{
if (p->start_state > BSS_PREPARE)
bgp_close(p, 1);
BGP_TRACE(D_EVENTS, "Down");
proto_notify_state(&p->p, PS_DOWN);
}
static void
bgp_decision(void *vp)
{
struct bgp_proto *p = vp;
DBG("BGP: Decision start\n");
if ((p->p.proto_state == PS_START)
&& (p->outgoing_conn.state == BS_IDLE)
&& (p->incoming_conn.state != BS_OPENCONFIRM)
&& (!p->cf->passive))
bgp_active(p);
if ((p->p.proto_state == PS_STOP)
&& (p->outgoing_conn.state == BS_IDLE)
&& (p->incoming_conn.state == BS_IDLE))
bgp_down(p);
}
void
bgp_stop(struct bgp_proto *p, unsigned subcode)
{
proto_notify_state(&p->p, PS_STOP);
bgp_graceful_close_conn(&p->outgoing_conn, subcode);
bgp_graceful_close_conn(&p->incoming_conn, subcode);
ev_schedule(p->event);
}
static inline void
bgp_conn_set_state(struct bgp_conn *conn, unsigned new_state)
{
if (conn->bgp->p.mrtdump & MD_STATES)
mrt_dump_bgp_state_change(conn, conn->state, new_state);
conn->state = new_state;
}
void
bgp_conn_enter_openconfirm_state(struct bgp_conn *conn)
{
/* Really, most of the work is done in bgp_rx_open(). */
bgp_conn_set_state(conn, BS_OPENCONFIRM);
}
void
bgp_conn_enter_established_state(struct bgp_conn *conn)
{
struct bgp_proto *p = conn->bgp;
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;
bgp_init_bucket_table(p);
bgp_init_prefix_table(p, 8);
int peer_gr_ready = conn->peer_gr_aware && !(conn->peer_gr_flags & BGP_GRF_RESTART);
if (p->p.gr_recovery && !peer_gr_ready)
proto_graceful_restart_unlock(&p->p);
if (p->p.gr_recovery && (p->cf->gr_mode == BGP_GR_ABLE) && peer_gr_ready)
p->p.gr_wait = 1;
if (p->gr_active)
tm_stop(p->gr_timer);
if (p->gr_active && (!conn->peer_gr_able || !(conn->peer_gr_aflags & BGP_GRF_FORWARDING)))
bgp_graceful_restart_done(p);
bgp_conn_set_state(conn, BS_ESTABLISHED);
proto_notify_state(&p->p, PS_UP);
}
static void
bgp_conn_leave_established_state(struct bgp_proto *p)
{
BGP_TRACE(D_EVENTS, "BGP session closed");
p->conn = NULL;
if (p->p.proto_state == PS_UP)
bgp_stop(p, 0);
}
void
bgp_conn_enter_close_state(struct bgp_conn *conn)
{
struct bgp_proto *p = conn->bgp;
int os = conn->state;
bgp_conn_set_state(conn, BS_CLOSE);
tm_stop(conn->keepalive_timer);
conn->sk->rx_hook = NULL;
/* Timeout for CLOSE state, if we cannot send notification soon then we just hangup */
bgp_start_timer(conn->hold_timer, 10);
if (os == BS_ESTABLISHED)
bgp_conn_leave_established_state(p);
}
void
bgp_conn_enter_idle_state(struct bgp_conn *conn)
{
struct bgp_proto *p = conn->bgp;
int os = conn->state;
bgp_close_conn(conn);
bgp_conn_set_state(conn, BS_IDLE);
ev_schedule(p->event);
if (os == BS_ESTABLISHED)
bgp_conn_leave_established_state(p);
}
/**
* bgp_handle_graceful_restart - handle detected BGP graceful restart
* @p: BGP instance
*
* This function is called when a BGP graceful restart of the neighbor is
* detected (when the TCP connection fails or when a new TCP connection
* appears). The function activates processing of the restart - starts routing
* table refresh cycle and activates BGP restart timer. The protocol state goes
* back to %PS_START, but changing BGP state back to %BS_IDLE is left for the
* caller.
*/
void
bgp_handle_graceful_restart(struct bgp_proto *p)
{
ASSERT(p->conn && (p->conn->state == BS_ESTABLISHED) && p->gr_ready);
BGP_TRACE(D_EVENTS, "Neighbor graceful restart detected%s",
p->gr_active ? " - already pending" : "");
proto_notify_state(&p->p, PS_START);
if (p->gr_active)
rt_refresh_end(p->p.main_ahook->table, p->p.main_ahook);
p->gr_active = 1;
bgp_start_timer(p->gr_timer, p->conn->peer_gr_time);
rt_refresh_begin(p->p.main_ahook->table, p->p.main_ahook);
}
/**
* bgp_graceful_restart_done - finish active BGP graceful restart
* @p: BGP instance
*
* This function is called when the active BGP graceful restart of the neighbor
* should be finished - either successfully (the neighbor sends all paths and
* reports end-of-RIB on the new session) or unsuccessfully (the neighbor does
* not support BGP graceful restart on the new session). The function ends
* routing table refresh cycle and stops BGP restart timer.
*/
void
bgp_graceful_restart_done(struct bgp_proto *p)
{
BGP_TRACE(D_EVENTS, "Neighbor graceful restart done");
p->gr_active = 0;
tm_stop(p->gr_timer);
rt_refresh_end(p->p.main_ahook->table, p->p.main_ahook);
}
/**
* bgp_graceful_restart_timeout - timeout of graceful restart 'restart timer'
* @t: timer
*
* This function is a timeout hook for @gr_timer, implementing BGP restart time
* limit for reestablisment of the BGP session after the graceful restart. When
* fired, we just proceed with the usual protocol restart.
*/
static void
bgp_graceful_restart_timeout(timer *t)
{
struct bgp_proto *p = t->data;
BGP_TRACE(D_EVENTS, "Neighbor graceful restart timeout");
bgp_stop(p, 0);
}
static void
bgp_send_open(struct bgp_conn *conn)
{
conn->start_state = conn->bgp->start_state;
// Default values, possibly changed by receiving capabilities.
conn->advertised_as = 0;
conn->peer_refresh_support = 0;
conn->peer_as4_support = 0;
conn->peer_add_path = 0;
conn->peer_gr_aware = 0;
conn->peer_gr_able = 0;
conn->peer_gr_time = 0;
conn->peer_gr_flags = 0;
conn->peer_gr_aflags = 0;
DBG("BGP: Sending open\n");
conn->sk->rx_hook = bgp_rx;
conn->sk->tx_hook = bgp_tx;
tm_stop(conn->connect_retry_timer);
bgp_schedule_packet(conn, PKT_OPEN);
bgp_conn_set_state(conn, BS_OPENSENT);
bgp_start_timer(conn->hold_timer, conn->bgp->cf->initial_hold_time);
}
static void
bgp_connected(sock *sk)
{
struct bgp_conn *conn = sk->data;
struct bgp_proto *p = conn->bgp;
BGP_TRACE(D_EVENTS, "Connected");
bgp_send_open(conn);
}
static void
bgp_connect_timeout(timer *t)
{
struct bgp_conn *conn = t->data;
struct bgp_proto *p = conn->bgp;
DBG("BGP: connect_timeout\n");
if (p->p.proto_state == PS_START)
{
bgp_close_conn(conn);
bgp_connect(p);
}
else
bgp_conn_enter_idle_state(conn);
}
static void
bgp_sock_err(sock *sk, int err)
{
struct bgp_conn *conn = sk->data;
struct bgp_proto *p = conn->bgp;
/*
* This error hook may be called either asynchronously from main
* loop, or synchronously from sk_send(). But sk_send() is called
* only from bgp_tx() and bgp_kick_tx(), which are both called
* asynchronously from main loop. Moreover, they end if err hook is
* called. Therefore, we could suppose that it is always called
* asynchronously.
*/
bgp_store_error(p, conn, BE_SOCKET, err);
if (err)
BGP_TRACE(D_EVENTS, "Connection lost (%M)", err);
else
BGP_TRACE(D_EVENTS, "Connection closed");
if ((conn->state == BS_ESTABLISHED) && p->gr_ready)
bgp_handle_graceful_restart(p);
bgp_conn_enter_idle_state(conn);
}
static void
bgp_hold_timeout(timer *t)
{
struct bgp_conn *conn = t->data;
struct bgp_proto *p = conn->bgp;
DBG("BGP: Hold timeout\n");
/* We are already closing the connection - just do hangup */
if (conn->state == BS_CLOSE)
{
BGP_TRACE(D_EVENTS, "Connection stalled");
bgp_conn_enter_idle_state(conn);
return;
}
/* If there is something in input queue, we are probably congested
and perhaps just not processed BGP packets in time. */
if (sk_rx_ready(conn->sk) > 0)
bgp_start_timer(conn->hold_timer, 10);
else
bgp_error(conn, 4, 0, NULL, 0);
}
static void
bgp_keepalive_timeout(timer *t)
{
struct bgp_conn *conn = t->data;
DBG("BGP: Keepalive timer\n");
bgp_schedule_packet(conn, PKT_KEEPALIVE);
}
static void
bgp_setup_conn(struct bgp_proto *p, struct bgp_conn *conn)
{
timer *t;
conn->sk = NULL;
conn->bgp = p;
conn->packets_to_send = 0;
t = conn->connect_retry_timer = tm_new(p->p.pool);
t->hook = bgp_connect_timeout;
t->data = conn;
t = conn->hold_timer = tm_new(p->p.pool);
t->hook = bgp_hold_timeout;
t->data = conn;
t = conn->keepalive_timer = tm_new(p->p.pool);
t->hook = bgp_keepalive_timeout;
t->data = conn;
conn->tx_ev = ev_new(p->p.pool);
conn->tx_ev->hook = bgp_kick_tx;
conn->tx_ev->data = conn;
}
static void
bgp_setup_sk(struct bgp_conn *conn, sock *s)
{
s->data = conn;
s->err_hook = bgp_sock_err;
conn->sk = s;
}
static void
bgp_active(struct bgp_proto *p)
{
int delay = MAX(1, p->cf->start_delay_time);
struct bgp_conn *conn = &p->outgoing_conn;
BGP_TRACE(D_EVENTS, "Connect delayed by %d seconds", delay);
bgp_setup_conn(p, conn);
bgp_conn_set_state(conn, BS_ACTIVE);
bgp_start_timer(conn->connect_retry_timer, delay);
}
/**
* bgp_connect - initiate an outgoing connection
* @p: BGP instance
*
* The bgp_connect() function creates a new &bgp_conn and initiates
* a TCP connection to the peer. The rest of connection setup is governed
* by the BGP state machine as described in the standard.
*/
static void
bgp_connect(struct bgp_proto *p) /* Enter Connect state and start establishing connection */
{
sock *s;
struct bgp_conn *conn = &p->outgoing_conn;
int hops = p->cf->multihop ? : 1;
DBG("BGP: Connecting\n");
s = sk_new(p->p.pool);
s->type = SK_TCP_ACTIVE;
s->saddr = p->source_addr;
s->daddr = p->cf->remote_ip;
s->iface = p->neigh ? p->neigh->iface : NULL;
s->dport = BGP_PORT;
s->ttl = p->cf->ttl_security ? 255 : hops;
s->rbsize = BGP_RX_BUFFER_SIZE;
s->tbsize = BGP_TX_BUFFER_SIZE;
s->tos = IP_PREC_INTERNET_CONTROL;
s->password = p->cf->password;
s->tx_hook = bgp_connected;
BGP_TRACE(D_EVENTS, "Connecting to %I%J from local address %I%J", s->daddr, p->cf->iface,
s->saddr, ipa_has_link_scope(s->saddr) ? s->iface : NULL);
bgp_setup_conn(p, conn);
bgp_setup_sk(conn, s);
bgp_conn_set_state(conn, BS_CONNECT);
if (sk_open(s) < 0)
{
bgp_sock_err(s, 0);
return;
}
/* Set minimal receive TTL if needed */
if (p->cf->ttl_security)
{
DBG("Setting minimum received TTL to %d", 256 - hops);
if (sk_set_min_ttl(s, 256 - hops) < 0)
{
log(L_ERR "TTL security configuration failed, closing session");
bgp_sock_err(s, 0);
return;
}
}
DBG("BGP: Waiting for connect success\n");
bgp_start_timer(conn->connect_retry_timer, p->cf->connect_retry_time);
}
/**
* bgp_incoming_connection - handle an incoming connection
* @sk: TCP socket
* @dummy: unused
*
* This function serves as a socket hook for accepting of new BGP
* connections. It searches a BGP instance corresponding to the peer
* which has connected and if such an instance exists, it creates a
* &bgp_conn structure, attaches it to the instance and either sends
* an Open message or (if there already is an active connection) it
* closes the new connection by sending a Notification message.
*/
static int
bgp_incoming_connection(sock *sk, int dummy UNUSED)
{
struct proto_config *pc;
DBG("BGP: Incoming connection from %I port %d\n", sk->daddr, sk->dport);
WALK_LIST(pc, config->protos)
if (pc->protocol == &proto_bgp && pc->proto)
{
struct bgp_proto *p = (struct bgp_proto *) pc->proto;
if (ipa_equal(p->cf->remote_ip, sk->daddr) &&
(!ipa_has_link_scope(sk->daddr) || (p->cf->iface == sk->iface)))
{
/* We are in proper state and there is no other incoming connection */
int acc = (p->p.proto_state == PS_START || p->p.proto_state == PS_UP) &&
(p->start_state >= BSS_CONNECT) && (!p->incoming_conn.sk);
if (p->conn && (p->conn->state == BS_ESTABLISHED) && p->gr_ready)
{
bgp_store_error(p, NULL, BE_MISC, BEM_GRACEFUL_RESTART);
bgp_handle_graceful_restart(p);
bgp_conn_enter_idle_state(p->conn);
acc = 1;
}
BGP_TRACE(D_EVENTS, "Incoming connection from %I%J (port %d) %s",
sk->daddr, ipa_has_link_scope(sk->daddr) ? sk->iface : NULL,
sk->dport, acc ? "accepted" : "rejected");
if (!acc)
goto err;
int hops = p->cf->multihop ? : 1;
if (p->cf->ttl_security)
{
/* TTL security support */
if ((sk_set_ttl(sk, 255) < 0) ||
(sk_set_min_ttl(sk, 256 - hops) < 0))
{
log(L_ERR "TTL security configuration failed, closing session");
goto err;
}
}
else
sk_set_ttl(sk, hops);
bgp_setup_conn(p, &p->incoming_conn);
bgp_setup_sk(&p->incoming_conn, sk);
bgp_send_open(&p->incoming_conn);
return 0;
}
}
log(L_WARN "BGP: Unexpected connect from unknown address %I%J (port %d)",
sk->daddr, ipa_has_link_scope(sk->daddr) ? sk->iface : NULL, sk->dport);
err:
rfree(sk);
return 0;
}
static void
bgp_listen_sock_err(sock *sk UNUSED, int err)
{
if (err == ECONNABORTED)
log(L_WARN "BGP: Incoming connection aborted");
else
log(L_ERR "BGP: Error on listening socket: %M", err);
}
static sock *
bgp_setup_listen_sk(ip_addr addr, unsigned port, u32 flags)
{
sock *s = sk_new(&root_pool);
DBG("BGP: Creating listening socket\n");
s->type = SK_TCP_PASSIVE;
s->ttl = 255;
s->saddr = addr;
s->sport = port ? port : BGP_PORT;
s->flags = flags ? 0 : SKF_V6ONLY;
s->tos = IP_PREC_INTERNET_CONTROL;
s->rbsize = BGP_RX_BUFFER_SIZE;
s->tbsize = BGP_TX_BUFFER_SIZE;
s->rx_hook = bgp_incoming_connection;
s->err_hook = bgp_listen_sock_err;
if (sk_open(s) < 0)
{
log(L_ERR "BGP: Unable to open listening socket");
rfree(s);
return NULL;
}
return s;
}
static void
bgp_start_neighbor(struct bgp_proto *p)
{
/* Called only for single-hop BGP sessions */
if (ipa_zero(p->source_addr))
p->source_addr = p->neigh->ifa->ip;
#ifdef IPV6
{
struct ifa *a;
p->local_link = IPA_NONE;
WALK_LIST(a, p->neigh->iface->addrs)
if (a->scope == SCOPE_LINK)
{
p->local_link = a->ip;
break;
}
if (! ipa_nonzero(p->local_link))
log(L_WARN "%s: Missing link local address on interface %s", p->p.name, p->neigh->iface->name);
DBG("BGP: Selected link-level address %I\n", p->local_link);
}
#endif
bgp_initiate(p);
}
static void
bgp_neigh_notify(neighbor *n)
{
struct bgp_proto *p = (struct bgp_proto *) n->proto;
if (! (n->flags & NEF_STICKY))
return;
if (n->scope > 0)
{
if ((p->p.proto_state == PS_START) && (p->start_state == BSS_PREPARE))
{
BGP_TRACE(D_EVENTS, "Neighbor found");
bgp_start_neighbor(p);
}
}
else
{
if ((p->p.proto_state == PS_START) || (p->p.proto_state == PS_UP))
{
BGP_TRACE(D_EVENTS, "Neighbor lost");
bgp_store_error(p, NULL, BE_MISC, BEM_NEIGHBOR_LOST);
bgp_stop(p, 0);
}
}
}
static void
bgp_bfd_notify(struct bfd_request *req)
{
struct bgp_proto *p = req->data;
int ps = p->p.proto_state;
if (req->down && ((ps == PS_START) || (ps == PS_UP)))
{
BGP_TRACE(D_EVENTS, "BFD session down");
bgp_store_error(p, NULL, BE_MISC, BEM_BFD_DOWN);
if (ps == PS_UP)
bgp_update_startup_delay(p);
bgp_stop(p, 0);
}
}
static void
bgp_update_bfd(struct bgp_proto *p, int use_bfd)
{
if (use_bfd && !p->bfd_req)
p->bfd_req = bfd_request_session(p->p.pool, p->cf->remote_ip, p->source_addr,
p->cf->multihop ? NULL : p->neigh->iface,
bgp_bfd_notify, p);
if (!use_bfd && p->bfd_req)
{
rfree(p->bfd_req);
p->bfd_req = NULL;
}
}
static int
bgp_reload_routes(struct proto *P)
{
struct bgp_proto *p = (struct bgp_proto *) P;
if (!p->conn || !p->conn->peer_refresh_support)
return 0;
bgp_schedule_packet(p->conn, PKT_ROUTE_REFRESH);
return 1;
}
static void
bgp_feed_done(struct proto *P)
{
struct bgp_proto *p = (struct bgp_proto *) P;
if (!p->conn || !p->cf->gr_mode)
return;
p->send_end_mark = 1;
bgp_schedule_packet(p->conn, PKT_UPDATE);
}
static void
bgp_start_locked(struct object_lock *lock)
{
struct bgp_proto *p = lock->data;
struct bgp_config *cf = p->cf;
if (p->p.proto_state != PS_START)
{
DBG("BGP: Got lock in different state %d\n", p->p.proto_state);
return;
}
DBG("BGP: Got lock\n");
if (cf->multihop)
{
/* Multi-hop sessions do not use neighbor entries */
bgp_initiate(p);
return;
}
p->neigh = neigh_find2(&p->p, &cf->remote_ip, cf->iface, NEF_STICKY);
if (!p->neigh || (p->neigh->scope == SCOPE_HOST))
{
log(L_ERR "%s: Invalid remote address %I%J", p->p.name, cf->remote_ip, cf->iface);
/* 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);
proto_notify_state(&p->p, PS_DOWN);
return;
}
if (p->neigh->scope > 0)
bgp_start_neighbor(p);
else
BGP_TRACE(D_EVENTS, "Waiting for %I%J to become my neighbor", cf->remote_ip, cf->iface);
}
static int
bgp_start(struct proto *P)
{
struct bgp_proto *p = (struct bgp_proto *) P;
struct object_lock *lock;
DBG("BGP: Startup.\n");
p->start_state = BSS_PREPARE;
p->outgoing_conn.state = BS_IDLE;
p->incoming_conn.state = BS_IDLE;
p->neigh = NULL;
p->bfd_req = NULL;
p->gr_ready = 0;
p->gr_active = 0;
rt_lock_table(p->igp_table);
p->event = ev_new(p->p.pool);
p->event->hook = bgp_decision;
p->event->data = p;
p->startup_timer = tm_new(p->p.pool);
p->startup_timer->hook = bgp_startup_timeout;
p->startup_timer->data = p;
p->gr_timer = tm_new(p->p.pool);
p->gr_timer->hook = bgp_graceful_restart_timeout;
p->gr_timer->data = p;
p->local_id = proto_get_router_id(P->cf);
if (p->rr_client)
p->rr_cluster_id = p->cf->rr_cluster_id ? p->cf->rr_cluster_id : p->local_id;
p->remote_id = 0;
p->source_addr = p->cf->source_addr;
if (p->p.gr_recovery && p->cf->gr_mode)
proto_graceful_restart_lock(P);
/*
* Before attempting to create the connection, we need to lock the
* port, so that are sure we're the only instance attempting to talk
* with that neighbor.
*/
lock = p->lock = olock_new(P->pool);
lock->addr = p->cf->remote_ip;
lock->iface = p->cf->iface;
lock->type = OBJLOCK_TCP;
lock->port = BGP_PORT;
lock->hook = bgp_start_locked;
lock->data = p;
olock_acquire(lock);
return PS_START;
}
extern int proto_restart;
static int
bgp_shutdown(struct proto *P)
{
struct bgp_proto *p = (struct bgp_proto *) P;
unsigned subcode = 0;
BGP_TRACE(D_EVENTS, "Shutdown requested");
switch (P->down_code)
{
case PDC_CF_REMOVE:
case PDC_CF_DISABLE:
subcode = 3; // Errcode 6, 3 - peer de-configured
break;
case PDC_CF_RESTART:
subcode = 6; // Errcode 6, 6 - other configuration change
break;
case PDC_CMD_DISABLE:
case PDC_CMD_SHUTDOWN:
subcode = 2; // Errcode 6, 2 - administrative shutdown
break;
case PDC_CMD_RESTART:
subcode = 4; // Errcode 6, 4 - administrative reset
break;
case PDC_RX_LIMIT_HIT:
case PDC_IN_LIMIT_HIT:
subcode = 1; // Errcode 6, 1 - max number of prefixes reached
/* log message for compatibility */
log(L_WARN "%s: Route limit exceeded, shutting down", p->p.name);
goto limit;
case PDC_OUT_LIMIT_HIT:
subcode = proto_restart ? 4 : 2; // Administrative reset or shutdown
limit:
bgp_store_error(p, NULL, BE_AUTO_DOWN, BEA_ROUTE_LIMIT_EXCEEDED);
if (proto_restart)
bgp_update_startup_delay(p);
else
p->startup_delay = 0;
goto done;
}
bgp_store_error(p, NULL, BE_MAN_DOWN, 0);
p->startup_delay = 0;
done:
bgp_stop(p, subcode);
return p->p.proto_state;
}
static void
bgp_cleanup(struct proto *P)
{
struct bgp_proto *p = (struct bgp_proto *) P;
rt_unlock_table(p->igp_table);
}
static rtable *
get_igp_table(struct bgp_config *cf)
{
return cf->igp_table ? cf->igp_table->table : cf->c.table->table;
}
static struct proto *
bgp_init(struct proto_config *C)
{
struct proto *P = proto_new(C, sizeof(struct bgp_proto));
struct bgp_config *c = (struct bgp_config *) C;
struct bgp_proto *p = (struct bgp_proto *) P;
P->accept_ra_types = c->secondary ? RA_ACCEPTED : RA_OPTIMAL;
P->rt_notify = bgp_rt_notify;
P->import_control = bgp_import_control;
P->neigh_notify = bgp_neigh_notify;
P->reload_routes = bgp_reload_routes;
P->feed_done = bgp_feed_done;
P->rte_better = bgp_rte_better;
P->rte_recalculate = c->deterministic_med ? bgp_rte_recalculate : NULL;
p->cf = c;
p->local_as = c->local_as;
p->remote_as = c->remote_as;
p->is_internal = (c->local_as == c->remote_as);
p->rs_client = c->rs_client;
p->rr_client = c->rr_client;
p->igp_table = get_igp_table(c);
return P;
}
void
bgp_check_config(struct bgp_config *c)
{
int internal = (c->local_as == c->remote_as);
/* Do not check templates at all */
if (c->c.class == SYM_TEMPLATE)
return;
/* EBGP direct by default, IBGP multihop by default */
if (c->multihop < 0)
c->multihop = internal ? 64 : 0;
/* Different default for gw_mode */
if (!c->gw_mode)
c->gw_mode = c->multihop ? GW_RECURSIVE : GW_DIRECT;
/* Different default based on rs_client */
if (!c->missing_lladdr)
c->missing_lladdr = c->rs_client ? MLL_IGNORE : MLL_SELF;
/* Disable after error incompatible with restart limit action */
if (c->c.in_limit && (c->c.in_limit->action == PLA_RESTART) && c->disable_after_error)
c->c.in_limit->action = PLA_DISABLE;
if (!c->local_as)
cf_error("Local AS number must be set");
if (!c->remote_as)
cf_error("Neighbor must be configured");
if (!(c->capabilities && c->enable_as4) && (c->remote_as > 0xFFFF))
cf_error("Neighbor AS number out of range (AS4 not available)");
if (!internal && c->rr_client)
cf_error("Only internal neighbor can be RR client");
if (internal && c->rs_client)
cf_error("Only external neighbor can be RS client");
if (c->multihop && (c->gw_mode == GW_DIRECT))
cf_error("Multihop BGP cannot use direct gateway mode");
if (c->multihop && (ipa_has_link_scope(c->remote_ip) ||
ipa_has_link_scope(c->source_addr)))
cf_error("Multihop BGP cannot be used with link-local addresses");
if (c->multihop && c->bfd && ipa_zero(c->source_addr))
cf_error("Multihop BGP with BFD requires specified source address");
if ((c->gw_mode == GW_RECURSIVE) && c->c.table->sorted)
cf_error("BGP in recursive mode prohibits sorted table");
if (c->deterministic_med && c->c.table->sorted)
cf_error("BGP with deterministic MED prohibits sorted table");
if (c->secondary && !c->c.table->sorted)
cf_error("BGP with secondary option requires sorted table");
}
static int
bgp_reconfigure(struct proto *P, struct proto_config *C)
{
struct bgp_config *new = (struct bgp_config *) C;
struct bgp_proto *p = (struct bgp_proto *) P;
struct bgp_config *old = p->cf;
if (proto_get_router_id(C) != p->local_id)
return 0;
int same = !memcmp(((byte *) old) + sizeof(struct proto_config),
((byte *) new) + sizeof(struct proto_config),
// password item is last and must be checked separately
OFFSETOF(struct bgp_config, password) - sizeof(struct proto_config))
&& ((!old->password && !new->password)
|| (old->password && new->password && !strcmp(old->password, new->password)))
&& (get_igp_table(old) == get_igp_table(new));
if (same && (p->start_state > BSS_PREPARE))
bgp_update_bfd(p, new->bfd);
/* We should update our copy of configuration ptr as old configuration will be freed */
if (same)
p->cf = new;
return same;
}
static void
bgp_copy_config(struct proto_config *dest, struct proto_config *src)
{
/* Just a shallow copy */
proto_copy_rest(dest, src, sizeof(struct bgp_config));
}
/**
* bgp_error - report a protocol error
* @c: connection
* @code: error code (according to the RFC)
* @subcode: error sub-code
* @data: data to be passed in the Notification message
* @len: length of the data
*
* bgp_error() sends a notification packet to tell the other side that a protocol
* error has occurred (including the data considered erroneous if possible) and
* closes the connection.
*/
void
bgp_error(struct bgp_conn *c, unsigned code, unsigned subcode, byte *data, int len)
{
struct bgp_proto *p = c->bgp;
if (c->state == BS_CLOSE)
return;
bgp_log_error(p, BE_BGP_TX, "Error", code, subcode, data, (len > 0) ? len : -len);
bgp_store_error(p, c, BE_BGP_TX, (code << 16) | subcode);
bgp_conn_enter_close_state(c);
c->notify_code = code;
c->notify_subcode = subcode;
c->notify_data = data;
c->notify_size = (len > 0) ? len : 0;
bgp_schedule_packet(c, PKT_NOTIFICATION);
if (code != 6)
{
bgp_update_startup_delay(p);
bgp_stop(p, 0);
}
}
/**
* bgp_store_error - store last error for status report
* @p: BGP instance
* @c: connection
* @class: error class (BE_xxx constants)
* @code: error code (class specific)
*
* bgp_store_error() decides whether given error is interesting enough
* and store that error to last_error variables of @p
*/
void
bgp_store_error(struct bgp_proto *p, struct bgp_conn *c, u8 class, u32 code)
{
/* During PS_UP, we ignore errors on secondary connection */
if ((p->p.proto_state == PS_UP) && c && (c != p->conn))
return;
/* During PS_STOP, we ignore any errors, as we want to report
* the error that caused transition to PS_STOP
*/
if (p->p.proto_state == PS_STOP)
return;
p->last_error_class = class;
p->last_error_code = code;
}
static char *bgp_state_names[] = { "Idle", "Connect", "Active", "OpenSent", "OpenConfirm", "Established", "Close" };
static char *bgp_err_classes[] = { "", "Error: ", "Socket: ", "Received: ", "BGP Error: ", "Automatic shutdown: ", ""};
static char *bgp_misc_errors[] = { "", "Neighbor lost", "Invalid next hop", "Kernel MD5 auth failed", "No listening socket", "BFD session down", "Graceful restart"};
static char *bgp_auto_errors[] = { "", "Route limit exceeded"};
static const char *
bgp_last_errmsg(struct bgp_proto *p)
{
switch (p->last_error_class)
{
case BE_MISC:
return bgp_misc_errors[p->last_error_code];
case BE_SOCKET:
return (p->last_error_code == 0) ? "Connection closed" : strerror(p->last_error_code);
case BE_BGP_RX:
case BE_BGP_TX:
return bgp_error_dsc(p->last_error_code >> 16, p->last_error_code & 0xFF);
case BE_AUTO_DOWN:
return bgp_auto_errors[p->last_error_code];
default:
return "";
}
}
static const char *
bgp_state_dsc(struct bgp_proto *p)
{
if (p->p.proto_state == PS_DOWN)
return "Down";
int state = MAX(p->incoming_conn.state, p->outgoing_conn.state);
if ((state == BS_IDLE) && (p->start_state >= BSS_CONNECT) && p->cf->passive)
return "Passive";
return bgp_state_names[state];
}
static void
bgp_get_status(struct proto *P, byte *buf)
{
struct bgp_proto *p = (struct bgp_proto *) P;
const char *err1 = bgp_err_classes[p->last_error_class];
const char *err2 = bgp_last_errmsg(p);
if (P->proto_state == PS_DOWN)
bsprintf(buf, "%s%s", err1, err2);
else
bsprintf(buf, "%-14s%s%s", bgp_state_dsc(p), err1, err2);
}
static void
bgp_show_proto_info(struct proto *P)
{
struct bgp_proto *p = (struct bgp_proto *) P;
struct bgp_conn *c = p->conn;
proto_show_basic_info(P);
cli_msg(-1006, " BGP state: %s", bgp_state_dsc(p));
cli_msg(-1006, " Neighbor address: %I%J", p->cf->remote_ip, p->cf->iface);
cli_msg(-1006, " Neighbor AS: %u", p->remote_as);
if (p->gr_active)
cli_msg(-1006, " Neighbor graceful restart active");
if (P->proto_state == PS_START)
{
struct bgp_conn *oc = &p->outgoing_conn;
if ((p->start_state < BSS_CONNECT) &&
(p->startup_timer->expires))
cli_msg(-1006, " Error wait: %d/%d",
p->startup_timer->expires - now, p->startup_delay);
if ((oc->state == BS_ACTIVE) &&
(oc->connect_retry_timer->expires))
cli_msg(-1006, " Start delay: %d/%d",
oc->connect_retry_timer->expires - now, p->cf->start_delay_time);
if (p->gr_active && p->gr_timer->expires)
cli_msg(-1006, " Restart timer: %d/-", p->gr_timer->expires - now);
}
else if (P->proto_state == PS_UP)
{
cli_msg(-1006, " Neighbor ID: %R", p->remote_id);
cli_msg(-1006, " Neighbor caps: %s%s%s%s%s",
c->peer_refresh_support ? " refresh" : "",
c->peer_gr_able ? " restart-able" : (c->peer_gr_aware ? " restart-aware" : ""),
c->peer_as4_support ? " AS4" : "",
(c->peer_add_path & ADD_PATH_RX) ? " add-path-rx" : "",
(c->peer_add_path & ADD_PATH_TX) ? " add-path-tx" : "");
cli_msg(-1006, " Session: %s%s%s%s%s%s%s",
p->is_internal ? "internal" : "external",
p->cf->multihop ? " multihop" : "",
p->rr_client ? " route-reflector" : "",
p->rs_client ? " route-server" : "",
p->as4_session ? " AS4" : "",
p->add_path_rx ? " add-path-rx" : "",
p->add_path_tx ? " add-path-tx" : "");
cli_msg(-1006, " Source address: %I", p->source_addr);
if (P->cf->in_limit)
cli_msg(-1006, " Route limit: %d/%d",
p->p.stats.imp_routes + p->p.stats.filt_routes, P->cf->in_limit->limit);
cli_msg(-1006, " Hold timer: %d/%d",
tm_remains(c->hold_timer), c->hold_time);
cli_msg(-1006, " Keepalive timer: %d/%d",
tm_remains(c->keepalive_timer), c->keepalive_time);
}
if ((p->last_error_class != BE_NONE) &&
(p->last_error_class != BE_MAN_DOWN))
{
const char *err1 = bgp_err_classes[p->last_error_class];
const char *err2 = bgp_last_errmsg(p);
cli_msg(-1006, " Last error: %s%s", err1, err2);
}
}
struct protocol proto_bgp = {
name: "BGP",
template: "bgp%d",
attr_class: EAP_BGP,
preference: DEF_PREF_BGP,
init: bgp_init,
start: bgp_start,
shutdown: bgp_shutdown,
cleanup: bgp_cleanup,
reconfigure: bgp_reconfigure,
copy_config: bgp_copy_config,
get_status: bgp_get_status,
get_attr: bgp_get_attr,
get_route_info: bgp_get_route_info,
show_proto_info: bgp_show_proto_info
};
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