bgp_fsm.c

大名鼎鼎的路由器源码。程序分ZEBRA、OSPFRIP等3个包。程序框架采用一个路由协议一个进程的方式

/* BGP-4 Finite State Machine   
   From RFC1771 [A Border Gateway Protocol 4 (BGP-4)]
   Copyright (C) 1996, 97, 98 Kunihiro Ishiguro

This file is part of GNU Zebra.

GNU Zebra is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version.

GNU Zebra is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Zebra; see the file COPYING.  If not, write to the Free
Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */

#include <zebra.h>

#include "linklist.h"
#include "prefix.h"
#include "vty.h"
#include "sockunion.h"
#include "thread.h"
#include "log.h"
#include "stream.h"
#include "memory.h"
#include "plist.h"

#include "bgpd/bgpd.h"
#include "bgpd/bgp_attr.h"
#include "bgpd/bgp_debug.h"
#include "bgpd/bgp_fsm.h"
#include "bgpd/bgp_packet.h"
#include "bgpd/bgp_network.h"
#include "bgpd/bgp_route.h"
#include "bgpd/bgp_dump.h"
#include "bgpd/bgp_open.h"
#ifdef HAVE_SNMP
#include "bgpd/bgp_snmp.h"
#endif /* HAVE_SNMP */

/* BGP FSM (finite state machine) has three types of functions.  Type
   one is thread functions.  Type two is event functions.  Type three
   is FSM functions.  Timer functions are set by bgp_timer_set
   function. */

/* BGP event function. */
int bgp_event (struct thread *);

/* BGP thread functions. */
static int bgp_start_timer (struct thread *);
static int bgp_connect_timer (struct thread *);
static int bgp_holdtime_timer (struct thread *);
static int bgp_keepalive_timer (struct thread *);

/* BGP FSM functions. */
static int bgp_start (struct peer *);

/* BGP start timer jitter. */
int
bgp_start_jitter (int time)
{
  return ((rand () % (time + 1)) - (time / 2));
}

/* Hook function called after bgp event is occered.  And vty's
   neighbor command invoke this function after making neighbor
   structure. */
void
bgp_timer_set (struct peer *peer)
{
  int jitter = 0;

  switch (peer->status)
    {
    case Idle:
      /* First entry point of peer's finite state machine.  In Idle
	 status start timer is on unless peer is shutdown or peer is
	 inactive.  All other timer must be turned off */
      if (CHECK_FLAG (peer->flags, PEER_FLAG_SHUTDOWN)
	  || CHECK_FLAG (peer->sflags, PEER_STATUS_PREFIX_OVERFLOW)
	  || ! peer_active (peer))
	{
	  BGP_TIMER_OFF (peer->t_start);
	}
      else
	{
	  jitter = bgp_start_jitter (peer->v_start);
	  BGP_TIMER_ON (peer->t_start, bgp_start_timer,
			peer->v_start + jitter);
	}
      BGP_TIMER_OFF (peer->t_connect);
      BGP_TIMER_OFF (peer->t_holdtime);
      BGP_TIMER_OFF (peer->t_keepalive);
      BGP_TIMER_OFF (peer->t_asorig);
      BGP_TIMER_OFF (peer->t_routeadv);
      break;

    case Connect:
      /* After start timer is expired, the peer moves to Connnect
         status.  Make sure start timer is off and connect timer is
         on. */
      BGP_TIMER_OFF (peer->t_start);
      BGP_TIMER_ON (peer->t_connect, bgp_connect_timer, peer->v_connect);
      BGP_TIMER_OFF (peer->t_holdtime);
      BGP_TIMER_OFF (peer->t_keepalive);
      BGP_TIMER_OFF (peer->t_asorig);
      BGP_TIMER_OFF (peer->t_routeadv);
      break;

    case Active:
      /* Active is waiting connection from remote peer.  And if
         connect timer is expired, change status to Connect. */
      BGP_TIMER_OFF (peer->t_start);
      /* If peer is passive mode, do not set connect timer. */
      if (CHECK_FLAG (peer->flags, PEER_FLAG_PASSIVE))
	{
	  BGP_TIMER_OFF (peer->t_connect);
	}
      else
	{
	  BGP_TIMER_ON (peer->t_connect, bgp_connect_timer, peer->v_connect);
	}
      BGP_TIMER_OFF (peer->t_holdtime);
      BGP_TIMER_OFF (peer->t_keepalive);
      BGP_TIMER_OFF (peer->t_asorig);
      BGP_TIMER_OFF (peer->t_routeadv);
      break;

    case OpenSent:
      /* OpenSent status. */
      BGP_TIMER_OFF (peer->t_start);
      BGP_TIMER_OFF (peer->t_connect);
      if (peer->v_holdtime != 0)
	{
	  BGP_TIMER_ON (peer->t_holdtime, bgp_holdtime_timer, 
			peer->v_holdtime);
	}
      else
	{
	  BGP_TIMER_OFF (peer->t_holdtime);
	}
      BGP_TIMER_OFF (peer->t_keepalive);
      BGP_TIMER_OFF (peer->t_asorig);
      BGP_TIMER_OFF (peer->t_routeadv);
      break;

    case OpenConfirm:
      /* OpenConfirm status. */
      BGP_TIMER_OFF (peer->t_start);
      BGP_TIMER_OFF (peer->t_connect);

      /* If the negotiated Hold Time value is zero, then the Hold Time
         timer and KeepAlive timers are not started. */
      if (peer->v_holdtime == 0)
	{
	  BGP_TIMER_OFF (peer->t_holdtime);
	  BGP_TIMER_OFF (peer->t_keepalive);
	}
      else
	{
	  BGP_TIMER_ON (peer->t_holdtime, bgp_holdtime_timer,
			peer->v_holdtime);
	  BGP_TIMER_ON (peer->t_keepalive, bgp_keepalive_timer, 
			peer->v_keepalive);
	}
      BGP_TIMER_OFF (peer->t_asorig);
      BGP_TIMER_OFF (peer->t_routeadv);
      break;

    case Established:
      /* In Established status start and connect timer is turned
         off. */
      BGP_TIMER_OFF (peer->t_start);
      BGP_TIMER_OFF (peer->t_connect);

      /* Same as OpenConfirm, if holdtime is zero then both holdtime
         and keepalive must be turned off. */
      if (peer->v_holdtime == 0)
	{
	  BGP_TIMER_OFF (peer->t_holdtime);
	  BGP_TIMER_OFF (peer->t_keepalive);
	}
      else
	{
	  BGP_TIMER_ON (peer->t_holdtime, bgp_holdtime_timer,
			peer->v_holdtime);
	  BGP_TIMER_ON (peer->t_keepalive, bgp_keepalive_timer,
			peer->v_keepalive);
	}
      BGP_TIMER_OFF (peer->t_asorig);
      break;
    }
}

/* BGP start timer.  This function set BGP_Start event to thread value
   and process event. */
static int
bgp_start_timer (struct thread *thread)
{
  struct peer *peer;

  peer = THREAD_ARG (thread);
  peer->t_start = NULL;

  if (BGP_DEBUG (fsm, FSM))
    zlog (peer->log, LOG_DEBUG,
	  "%s [FSM] Timer (start timer expire).", peer->host);

  THREAD_VAL (thread) = BGP_Start;
  bgp_event (thread);

  return 0;
}

/* BGP connect retry timer. */
static int
bgp_connect_timer (struct thread *thread)
{
  struct peer *peer;

  peer = THREAD_ARG (thread);
  peer->t_connect = NULL;

  if (BGP_DEBUG (fsm, FSM))
    zlog (peer->log, LOG_DEBUG, "%s [FSM] Timer (connect timer expire)",
	  peer->host);

  THREAD_VAL (thread) = ConnectRetry_timer_expired;
  bgp_event (thread);

  return 0;
}

/* BGP holdtime timer. */
static int
bgp_holdtime_timer (struct thread *thread)
{
  struct peer *peer;

  peer = THREAD_ARG (thread);
  peer->t_holdtime = NULL;

  if (BGP_DEBUG (fsm, FSM))
    zlog (peer->log, LOG_DEBUG,
	  "%s [FSM] Timer (holdtime timer expire)",
	  peer->host);

  THREAD_VAL (thread) = Hold_Timer_expired;
  bgp_event (thread);

  return 0;
}

/* BGP keepalive fire ! */
static int
bgp_keepalive_timer (struct thread *thread)
{
  struct peer *peer;

  peer = THREAD_ARG (thread);
  peer->t_keepalive = NULL;

  if (BGP_DEBUG (fsm, FSM))
    zlog (peer->log, LOG_DEBUG,
	  "%s [FSM] Timer (keepalive timer expire)",
	  peer->host);

  THREAD_VAL (thread) = KeepAlive_timer_expired;
  bgp_event (thread);

  return 0;
}

int
bgp_routeadv_timer (struct thread *thread)
{
  struct peer *peer;

  peer = THREAD_ARG (thread);
  peer->t_routeadv = NULL;

  if (BGP_DEBUG (fsm, FSM))
    zlog (peer->log, LOG_DEBUG,
	  "%s [FSM] Timer (routeadv timer expire)",
	  peer->host);

  peer->synctime = time (NULL);

  BGP_WRITE_ON (peer->t_write, bgp_write, peer->fd);

  BGP_TIMER_ON (peer->t_routeadv, bgp_routeadv_timer,
		peer->v_routeadv);

  return 0;
}

/* Reset bgp update timer */
static void
bgp_uptime_reset (struct peer *peer)
{
  peer->uptime = time (NULL);
}

/* BGP Peer Down Cause */
char *peer_down_str[] =
{
  "",
  "Router ID changed",
  "Remote AS changed",
  "Local AS change",
  "Cluster ID changed",
  "Confederation identifier changed",
  "Confederation peer changed",
  "RR client config change",
  "RS client config change",
  "Update source change",
  "Address family activated",
  "Admin. shutdown",
  "User reset",
  "BGP Notification received",
  "BGP Notification send",
  "Peer closed the session",
  "Neighbor deleted",
  "Peer-group add member",
  "Peer-group delete member",
  "Capability changed",
  "Passive config change",
  "Multihop config change"
};

/* Administrative BGP peer stop event. */
int
bgp_stop (struct peer *peer)
{
  int established = 0;
  afi_t afi;
  safi_t safi;
  char orf_name[BUFSIZ];

  /* Increment Dropped count. */
  if (peer->status == Established)
    {
      established = 1;
      peer->dropped++;
      bgp_fsm_change_status (peer, Idle);

      /* bgp log-neighbor-changes of neighbor Down */
      if (bgp_flag_check (peer->bgp, BGP_FLAG_LOG_NEIGHBOR_CHANGES))
	zlog_info ("%%ADJCHANGE: neighbor %s Down %s", peer->host,
		   peer_down_str [(int) peer->last_reset]);

      /* set last reset time */
      peer->resettime = time (NULL);

#ifdef HAVE_SNMP
      bgpTrapBackwardTransition (peer);
#endif /* HAVE_SNMP */
    }

  /* Reset uptime. */
  bgp_uptime_reset (peer);

  /* Need of clear of peer. */
  if (established)
    bgp_clear_route_all (peer);

  /* Stop read and write threads when exists. */
  BGP_READ_OFF (peer->t_read);
  BGP_WRITE_OFF (peer->t_write);

  /* Stop all timers. */
  BGP_TIMER_OFF (peer->t_start);
  BGP_TIMER_OFF (peer->t_connect);
  BGP_TIMER_OFF (peer->t_holdtime);
  BGP_TIMER_OFF (peer->t_keepalive);
  BGP_TIMER_OFF (peer->t_asorig);
  BGP_TIMER_OFF (peer->t_routeadv);

  /* Delete all existing events of the peer. */
  BGP_EVENT_DELETE (peer);

  /* Stream reset. */
  peer->packet_size = 0;

  /* Clear input and output buffer.  */
  if (peer->ibuf)
    stream_reset (peer->ibuf);
  if (peer->work)
    stream_reset (peer->work);
  stream_fifo_clean (peer->obuf);

  /* Close of file descriptor. */
  if (peer->fd >= 0)
    {
      close (peer->fd);
      peer->fd = -1;
    }

  /* Connection information. */
  if (peer->su_local)
    {
      XFREE (MTYPE_SOCKUNION, peer->su_local);
      peer->su_local = NULL;
    }

  if (peer->su_remote)
    {
      XFREE (MTYPE_SOCKUNION, peer->su_remote);
      peer->su_remote = NULL;
    }

  /* Clear remote router-id. */
  peer->remote_id.s_addr = 0;

  /* Reset all negotiated variables */
  peer->afc_nego[AFI_IP][SAFI_UNICAST] = 0;
  peer->afc_nego[AFI_IP][SAFI_MULTICAST] = 0;
  peer->afc_nego[AFI_IP][SAFI_MPLS_VPN] = 0;
  peer->afc_nego[AFI_IP6][SAFI_UNICAST] = 0;
  peer->afc_nego[AFI_IP6][SAFI_MULTICAST] = 0;
  peer->afc_adv[AFI_IP][SAFI_UNICAST] = 0;
  peer->afc_adv[AFI_IP][SAFI_MULTICAST] = 0;
  peer->afc_adv[AFI_IP][SAFI_MPLS_VPN] = 0;
  peer->afc_adv[AFI_IP6][SAFI_UNICAST] = 0;
  peer->afc_adv[AFI_IP6][SAFI_MULTICAST] = 0;
  peer->afc_recv[AFI_IP][SAFI_UNICAST] = 0;
  peer->afc_recv[AFI_IP][SAFI_MULTICAST] = 0;
  peer->afc_recv[AFI_IP][SAFI_MPLS_VPN] = 0;
  peer->afc_recv[AFI_IP6][SAFI_UNICAST] = 0;
  peer->afc_recv[AFI_IP6][SAFI_MULTICAST] = 0;

  /* Reset route refresh flag. */
  UNSET_FLAG (peer->cap, PEER_CAP_REFRESH_ADV);
  UNSET_FLAG (peer->cap, PEER_CAP_REFRESH_OLD_RCV);
  UNSET_FLAG (peer->cap, PEER_CAP_REFRESH_NEW_RCV);
  UNSET_FLAG (peer->cap, PEER_CAP_DYNAMIC_ADV);
  UNSET_FLAG (peer->cap, PEER_CAP_DYNAMIC_RCV);

  for (afi = AFI_IP ; afi < AFI_MAX ; afi++)
    for (safi = SAFI_UNICAST ; safi < SAFI_MAX ; safi++)
      {
	/* peer address family capability flags*/
	peer->af_cap[afi][safi] = 0;
	/* peer address family status flags*/
	peer->af_sflags[afi][safi] = 0;
	/* Received ORF prefix-filter */
	peer->orf_plist[afi][safi] = NULL;