bgp_packet.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

  /* If peer does not have the capability, send notification. */
  if (! CHECK_FLAG (peer->cap, PEER_CAP_REFRESH_ADV))
    {
      plog_err (peer->log, "%s [Error] BGP route refresh is not enabled",
		peer->host);
      bgp_notify_send (peer,
		       BGP_NOTIFY_HEADER_ERR,
		       BGP_NOTIFY_HEADER_BAD_MESTYPE);
      return;
    }

  /* Status must be Established. */
  if (peer->status != Established) 
    {
      plog_err (peer->log,
		"%s [Error] Route refresh packet received under status %s",
		peer->host, LOOKUP (bgp_status_msg, peer->status));
      bgp_notify_send (peer, BGP_NOTIFY_FSM_ERR, 0);
      return;
    }

  s = peer->ibuf;
  
  /* Parse packet. */
  afi = stream_getw (s);
  reserved = stream_getc (s);
  safi = stream_getc (s);

  if (BGP_DEBUG (normal, NORMAL))
    zlog_info ("%s rcvd REFRESH_REQ for afi/safi: %d/%d",
	       peer->host, afi, safi);

  /* Check AFI and SAFI. */
  if ((afi != AFI_IP && afi != AFI_IP6)
      || (safi != SAFI_UNICAST && safi != SAFI_MULTICAST
	  && safi != BGP_SAFI_VPNV4))
    {
      if (BGP_DEBUG (normal, NORMAL))
	{
	  zlog_info ("%s REFRESH_REQ for unrecognized afi/safi: %d/%d - ignored",
		     peer->host, afi, safi);
	}
      return;
    }

  /* Adjust safi code. */
  if (safi == BGP_SAFI_VPNV4)
    safi = SAFI_MPLS_VPN;

  if (size != BGP_MSG_ROUTE_REFRESH_MIN_SIZE - BGP_HEADER_SIZE)
    {
      u_char *end;
      u_char when_to_refresh;
      u_char orf_type;
      u_int16_t orf_len;

      if (size - (BGP_MSG_ROUTE_REFRESH_MIN_SIZE - BGP_HEADER_SIZE) < 5)
        {
          zlog_info ("%s ORF route refresh length error", peer->host);
          bgp_notify_send (peer, BGP_NOTIFY_CEASE, 0);
          return;
        }

      when_to_refresh = stream_getc (s);
      end = stream_pnt (s) + (size - 5);

      while (stream_pnt (s) < end)
	{
	  orf_type = stream_getc (s); 
	  orf_len = stream_getw (s);

	  if (orf_type == ORF_TYPE_PREFIX
	      || orf_type == ORF_TYPE_PREFIX_OLD)
	    {
	      u_char *p_pnt = stream_pnt (s);
	      u_char *p_end = stream_pnt (s) + orf_len;
	      struct orf_prefix orfp;
	      u_char common = 0;
	      u_int32_t seq;
	      int psize;
	      char name[BUFSIZ];
	      char buf[BUFSIZ];
	      int ret;

	      if (BGP_DEBUG (normal, NORMAL))
		{
		  zlog_info ("%s rcvd Prefixlist ORF(%d) length %d",
			     peer->host, orf_type, orf_len);
		}

	      /* ORF prefix-list name */
	      sprintf (name, "%s.%d.%d", peer->host, afi, safi);

	      while (p_pnt < p_end)
		{
		  memset (&orfp, 0, sizeof (struct orf_prefix));
		  common = *p_pnt++;
		  if (common & ORF_COMMON_PART_REMOVE_ALL)
		    {
		      if (BGP_DEBUG (normal, NORMAL))
			zlog_info ("%s rcvd Remove-All pfxlist ORF request", peer->host);
		      prefix_bgp_orf_remove_all (name);
		      break;
		    }
		  memcpy (&seq, p_pnt, sizeof (u_int32_t));
		  p_pnt += sizeof (u_int32_t);
		  orfp.seq = ntohl (seq);
		  orfp.ge = *p_pnt++;
		  orfp.le = *p_pnt++;
		  orfp.p.prefixlen = *p_pnt++;
		  orfp.p.family = afi2family (afi);
		  psize = PSIZE (orfp.p.prefixlen);
		  memcpy (&orfp.p.u.prefix, p_pnt, psize);
		  p_pnt += psize;

		  if (BGP_DEBUG (normal, NORMAL))
		    zlog_info ("%s rcvd %s %s seq %u %s/%d ge %d le %d",
			       peer->host,
			       (common & ORF_COMMON_PART_REMOVE ? "Remove" : "Add"), 
			       (common & ORF_COMMON_PART_DENY ? "deny" : "permit"),
			       orfp.seq, 
			       inet_ntop (orfp.p.family, &orfp.p.u.prefix, buf, BUFSIZ),
			       orfp.p.prefixlen, orfp.ge, orfp.le);

		  ret = prefix_bgp_orf_set (name, afi, &orfp,
				 (common & ORF_COMMON_PART_DENY ? 0 : 1 ),
				 (common & ORF_COMMON_PART_REMOVE ? 0 : 1));

		  if (ret != CMD_SUCCESS)
		    {
		      if (BGP_DEBUG (normal, NORMAL))
			zlog_info ("%s Received misformatted prefixlist ORF. Remove All pfxlist", peer->host);
		      prefix_bgp_orf_remove_all (name);
		      break;
		    }
		}
	      peer->orf_plist[afi][safi] =
			 prefix_list_lookup (AFI_ORF_PREFIX, name);
	    }
	  stream_forward (s, orf_len);
	}
      if (BGP_DEBUG (normal, NORMAL))
	zlog_info ("%s rcvd Refresh %s ORF request", peer->host,
		   when_to_refresh == REFRESH_DEFER ? "Defer" : "Immediate");
      if (when_to_refresh == REFRESH_DEFER)
	return;
    }

  /* First update is deferred until ORF or ROUTE-REFRESH is received */
  if (CHECK_FLAG (peer->af_sflags[afi][safi], PEER_STATUS_ORF_WAIT_REFRESH))
    UNSET_FLAG (peer->af_sflags[afi][safi], PEER_STATUS_ORF_WAIT_REFRESH);

  /* Perform route refreshment to the peer */
  bgp_announce_route (peer, afi, safi);
}

int
bgp_capability_msg_parse (struct peer *peer, u_char *pnt, bgp_size_t length)
{
  u_char *end;
  struct capability cap;
  u_char action;
  struct bgp *bgp;
  afi_t afi;
  safi_t safi;

  bgp = peer->bgp;
  end = pnt + length;

  while (pnt < end)
    {
      /* We need at least action, capability code and capability length. */
      if (pnt + 3 > end)
        {
          zlog_info ("%s Capability length error", peer->host);
          bgp_notify_send (peer, BGP_NOTIFY_CEASE, 0);
          return -1;
        }

      action = *pnt;

      /* Fetch structure to the byte stream. */
      memcpy (&cap, pnt + 1, sizeof (struct capability));

      /* Action value check.  */
      if (action != CAPABILITY_ACTION_SET
	  && action != CAPABILITY_ACTION_UNSET)
        {
          zlog_info ("%s Capability Action Value error %d",
		     peer->host, action);
          bgp_notify_send (peer, BGP_NOTIFY_CEASE, 0);
          return -1;
        }

      if (BGP_DEBUG (normal, NORMAL))
	zlog_info ("%s CAPABILITY has action: %d, code: %u, length %u",
		   peer->host, action, cap.code, cap.length);

      /* Capability length check. */
      if (pnt + (cap.length + 3) > end)
        {
          zlog_info ("%s Capability length error", peer->host);
          bgp_notify_send (peer, BGP_NOTIFY_CEASE, 0);
          return -1;
        }

      /* We know MP Capability Code. */
      if (cap.code == CAPABILITY_CODE_MP)
        {
	  afi = ntohs (cap.mpc.afi);
	  safi = cap.mpc.safi;

          /* Ignore capability when override-capability is set. */
          if (CHECK_FLAG (peer->flags, PEER_FLAG_OVERRIDE_CAPABILITY))
	    continue;

	  /* Address family check.  */
	  if ((afi == AFI_IP 
	       || afi == AFI_IP6)
	      && (safi == SAFI_UNICAST 
		  || safi == SAFI_MULTICAST 
		  || safi == BGP_SAFI_VPNV4))
	    {
	      if (BGP_DEBUG (normal, NORMAL))
		zlog_info ("%s CAPABILITY has %s MP_EXT CAP for afi/safi: %u/%u",
			   peer->host,
			   action == CAPABILITY_ACTION_SET 
			   ? "Advertising" : "Removing",
			   ntohs(cap.mpc.afi) , cap.mpc.safi);
		  
	      /* Adjust safi code. */
	      if (safi == BGP_SAFI_VPNV4)
		safi = SAFI_MPLS_VPN;
	      
	      if (action == CAPABILITY_ACTION_SET)
		{
		  peer->afc_recv[afi][safi] = 1;
		  if (peer->afc[afi][safi])
		    {
		      peer->afc_nego[afi][safi] = 1;
		      bgp_announce_route (peer, afi, safi);
		    }
		}
	      else
		{
		  peer->afc_recv[afi][safi] = 0;
		  peer->afc_nego[afi][safi] = 0;

		  if (peer_active_nego (peer))
		    bgp_clear_route (peer, afi, safi);
		  else
		    BGP_EVENT_ADD (peer, BGP_Stop);
		} 
	    }
        }
      else if (cap.code == CAPABILITY_CODE_REFRESH
	       || cap.code == CAPABILITY_CODE_REFRESH_OLD)
        {
          /* Check length. */
          if (cap.length != 0)
            {
              zlog_info ("%s Route Refresh Capability length error %d",
                         peer->host, cap.length);
              bgp_notify_send (peer, BGP_NOTIFY_CEASE, 0);
              return -1;
            }
	  
          if (BGP_DEBUG (normal, NORMAL))
            zlog_info ("%s CAPABILITY has %s ROUTE-REFRESH capability(%s) for all address-families",
		       peer->host,
		       action == CAPABILITY_ACTION_SET
		       ? "Advertising" : "Removing",
		       cap.code == CAPABILITY_CODE_REFRESH_OLD
		       ? "old" : "new");
	  
          /* BGP refresh capability */
	  if (action == CAPABILITY_ACTION_SET)
	    {
	      if (cap.code == CAPABILITY_CODE_REFRESH_OLD)
		SET_FLAG (peer->cap, PEER_CAP_REFRESH_OLD_RCV);
	      else
		SET_FLAG (peer->cap, PEER_CAP_REFRESH_NEW_RCV);
	    }
	  else
	    {
	      if (cap.code == CAPABILITY_CODE_REFRESH_OLD)
		UNSET_FLAG (peer->cap, PEER_CAP_REFRESH_OLD_RCV);
	      else
		UNSET_FLAG (peer->cap, PEER_CAP_REFRESH_NEW_RCV);
	    }
        }
      else
        {
          zlog_warn ("%s unrecognized capability code: %d - ignored",
                     peer->host, cap.code);
        }
      pnt += cap.length + 3;
    }
  return 0;
}

/* Dynamic Capability is received. */
void
bgp_capability_receive (struct peer *peer, bgp_size_t size)
{
  u_char *pnt;
  int ret;

  /* Fetch pointer. */
  pnt = stream_pnt (peer->ibuf);

  if (BGP_DEBUG (normal, NORMAL))
    zlog_info ("%s rcv CAPABILITY", peer->host);

  /* If peer does not have the capability, send notification. */
  if (! CHECK_FLAG (peer->cap, PEER_CAP_DYNAMIC_ADV))
    {
      plog_err (peer->log, "%s [Error] BGP dynamic capability is not enabled",
		peer->host);
      bgp_notify_send (peer,
		       BGP_NOTIFY_HEADER_ERR,
		       BGP_NOTIFY_HEADER_BAD_MESTYPE);
      return;
    }

  /* Status must be Established. */
  if (peer->status != Established)
    {
      plog_err (peer->log,
		"%s [Error] Dynamic capability packet received under status %s", peer->host, LOOKUP (bgp_status_msg, peer->status));
      bgp_notify_send (peer, BGP_NOTIFY_FSM_ERR, 0);
      return;
    }

  /* Parse packet. */
  ret = bgp_capability_msg_parse (peer, pnt, size);
}

/* BGP read utility function. */
int
bgp_read_packet (struct peer *peer)
{
  int nbytes;
  int readsize;

  readsize = peer->packet_size - peer->ibuf->putp;

  /* If size is zero then return. */
  if (! readsize)
    return 0;

  /* Read packet from fd. */
  nbytes = stream_read_unblock (peer->ibuf, peer->fd, readsize);

  /* If read byte is smaller than zero then error occured. */
  if (nbytes < 0) 
    {
      if (errno == EAGAIN)
	return -1;

      plog_err (peer->log, "%s [Error] bgp_read_packet error: %s",
		 peer->host, strerror (errno));
      BGP_EVENT_ADD (peer, TCP_fatal_error);
      return -1;
    }  

  /* When read byte is zero : clear bgp peer and return */
  if (nbytes == 0) 
    {
      if (BGP_DEBUG (events, EVENTS))
	plog_info (peer->log, "%s [Event] BGP connection closed fd %d",
		   peer->host, peer->fd);

      if (peer->status == Established) 
	peer->last_reset = PEER_DOWN_CLOSE_SESSION;

      BGP_EVENT_ADD (peer, TCP_connection_closed);
      return -1;
    }

  /* We read partial packet. */
  if (peer->ibuf->putp != peer->packet_size)
    return -1;

  return 0;
}

/* Marker check. */
int
bgp_marker_all_one (struct stream *s, int length)
{
  int i;

  for (i = 0; i < length; i++)
    if (s->data[i] != 0xff)
      return 0;

  return 1;
}

/* Starting point of packet process function. */
int
bgp_read (struct thread *thread)
{
  int ret;
  u_char type = 0;
  struct peer *peer;
  bgp_size_t size;
  char notify_data_length[2];

  /* Yes first of all get peer pointer. */
  peer = THREAD_ARG (thread);
  peer->t_read = NULL;

  /* For non-blocking IO check. */
  if (peer->status == Connect)
    {
      bgp_connect_check (peer);
      goto done;
    }
  else
    {
      if (peer->fd < 0)
	{
	  zlog_err ("bgp_read peer's fd is negative value %d", peer->fd);
	  return -1;
	}
      BGP_READ_ON (peer->t_read, bgp_read, peer->fd);
    }

  /* Read packet header to determine type of the packet */
  if (peer->packet_size == 0)
    peer->packet_size = BGP_HEADER_SIZE;

  if (peer->ibuf->putp < BGP_HEADER_SIZE)
    {
      ret = bgp_read_packet (peer);

      /* Header read error or partial read packet. */
      if (ret < 0) 
	goto done;

      /* Get size and type. */
      stream_forward (peer->ibuf, BGP_MARKER_SIZE);
      memcpy (notify_data_length, stream_pnt (peer->ibuf), 2);
      size = stream_getw (peer->ibuf);
      type = stream_getc (peer->ibuf);

      if (BGP_DEBUG (normal, NORMAL) && type != 2 && type != 0)
	zlog_info ("%s rcv message type %d, length (excl. header) %d",
		   peer->host, type, size - BGP_HEADER_SIZE);

      /* Marker check */
      if (type == BGP_MSG_OPEN
	  && ! bgp_marker_all_one (peer->ibuf, BGP_MARKER_SIZE))
	{
	  bgp_notify_send (peer,
			   BGP_NOTIFY_HEADER_ERR, 
			   BGP_NOTIFY_HEADER_NOT_SYNC);
	  goto done;
	}

      /* BGP type check. */
      if (type != BGP_MSG_OPEN && type != BGP_MSG_UPDATE 
	  && type != BGP_MSG_NOTIFY && type != BGP_MSG_KEEPALIVE 
	  && type != BGP_MSG_ROUTE_REFRESH_NEW
	  && type != BGP_MSG_ROUTE_REFRESH_OLD
	  && type != BGP_MSG_CAPABILITY)
	{
	  if (BGP_DEBUG (normal, NORMAL))
	    plog_err (peer->log,
		      "%s unknown message type 0x%02x",
		      peer->host, type);
	  bgp_notify_send_with_data (peer,
				     BGP_NOTIFY_HEADER_ERR,
			 	     BGP_NOTIFY_HEADER_BAD_MESTYPE,
				     &type, 1);
	  goto done;
	}
      /* Mimimum packet length check. */
      if ((size < BGP_HEADER_SIZE)
	  || (size > BGP_MAX_PACKET_SIZE)
	  || (type == BGP_MSG_OPEN && size < BGP_MSG_OPEN_MIN_SIZE)
	  || (type == BGP_MSG_UPDATE && size < BGP_MSG_UPDATE_MIN_SIZE)
	  || (type == BGP_MSG_NOTIFY && size < BGP_MSG_NOTIFY_MIN_SIZE)
	  || (type == BGP_MSG_KEEPALIVE && size != BGP_MSG_KEEPALIVE_MIN_SIZE)
	  || (type == BGP_MSG_ROUTE_REFRESH_NEW && size < BGP_MSG_ROUTE_REFRESH_MIN_SIZE)
	  || (type == BGP_MSG_ROUTE_REFRESH_OLD && size < BGP_MSG_ROUTE_REFRESH_MIN_SIZE)
	  || (type == BGP_MSG_CAPABILITY && size < BGP_MSG_CAPABILITY_MIN_SIZE))
	{
	  if (BGP_DEBUG (normal, NORMAL))
	    plog_err (peer->log,
		      "%s bad message length - %d for %s",
		      peer->host, size, 
		      type == 128 ? "ROUTE-REFRESH" :
		      bgp_type_str[(int) type]);
	  bgp_notify_send_with_data (peer,
				     BGP_NOTIFY_HEADER_ERR,
			  	     BGP_NOTIFY_HEADER_BAD_MESLEN,
				     notify_data_length, 2);
	  goto done;
	}

      /* Adjust size to message length. */
      peer->packet_size = size;
    }

  ret = bgp_read_packet (peer);
  if (ret < 0) 
    goto done;

  /* Get size and type again. */
  size = stream_getw_from (peer->ibuf, BGP_MARKER_SIZE);
  type = stream_getc_from (peer->ibuf, BGP_MARKER_SIZE + 2);

  /* BGP packet dump function. */
  bgp_dump_packet (peer, type, peer->ibuf);
  
  size = (peer->packet_size - BGP_HEADER_SIZE);

  /* Read rest of the packet and call each sort of packet routine */
  switch (type) 
    {
    case BGP_MSG_OPEN:
      peer->open_in++;
      bgp_open_receive (peer, size);
      break;
    case BGP_MSG_UPDATE:
      peer->readtime = time(NULL);    /* Last read timer reset */
      bgp_update_receive (peer, size);
      break;
    case BGP_MSG_NOTIFY:
      bgp_notify_receive (peer, size);
      break;
    case BGP_MSG_KEEPALIVE:
      peer->readtime = time(NULL);    /* Last read timer reset */
      bgp_keepalive_receive (peer, size);
      break;
    case BGP_MSG_ROUTE_REFRESH_NEW:
    case BGP_MSG_ROUTE_REFRESH_OLD:
      peer->refresh_in++;
      bgp_route_refresh_receive (peer, size);
      break;
    case BGP_MSG_CAPABILITY:
      peer->dynamic_cap_in++;
      bgp_capability_receive (peer, size);
      break;
    }

  /* Clear input buffer. */
  peer->packet_size = 0;
  if (peer->ibuf)
    stream_reset (peer->ibuf);

 done:
  if (CHECK_FLAG (peer->sflags, PEER_STATUS_ACCEPT_PEER))
    {
      if (BGP_DEBUG (events, EVENTS))
	zlog_info ("%s [Event] Accepting BGP peer delete", peer->host);
      peer_delete (peer);
    }
  return 0;
}