ospf_packet.c

router source code for the ospdf.

/*
 * OSPF Sending and Receiving OSPF Packets.
 * Copyright (C) 1999, 2000 Toshiaki Takada
 *
 * 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 "thread.h"
#include "memory.h"
#include "linklist.h"
#include "prefix.h"
#include "if.h"
#include "table.h"
#include "sockunion.h"
#include "stream.h"
#include "log.h"
#include "md5-gnu.h"

#include "ospfd/ospfd.h"
#include "ospfd/ospf_network.h"
#include "ospfd/ospf_interface.h"
#include "ospfd/ospf_ism.h"
#include "ospfd/ospf_asbr.h"
#include "ospfd/ospf_lsa.h"
#include "ospfd/ospf_lsdb.h"
#include "ospfd/ospf_neighbor.h"
#include "ospfd/ospf_nsm.h"
#include "ospfd/ospf_packet.h"
#include "ospfd/ospf_spf.h"
#include "ospfd/ospf_flood.h"
#include "ospfd/ospf_dump.h"

static void ospf_ls_ack_send_list (struct ospf_interface *, list,
				   struct in_addr);

/* Packet Type String. */
char *ospf_packet_type_str[] =
{
  "unknown",
  "Hello",
  "Database Description",
  "Link State Request",
  "Link State Update",
  "Link State Acknowledgment",
};

extern int in_cksum (void *ptr, int nbytes);

/* OSPF authentication checking function */
int
ospf_auth_type (struct ospf_interface *oi)
{
  int auth_type;

  if (OSPF_IF_PARAM (oi, auth_type) == OSPF_AUTH_NOTSET)
    auth_type = oi->area->auth_type;
  else
    auth_type = OSPF_IF_PARAM (oi, auth_type);

  /* Handle case where MD5 key list is not configured aka Cisco */
  if (auth_type == OSPF_AUTH_CRYPTOGRAPHIC &&
      list_isempty (OSPF_IF_PARAM (oi, auth_crypt)))
    return OSPF_AUTH_NULL;
  
  return auth_type;

}

/* forward output pointer. */
void
ospf_output_forward (struct stream *s, int size)
{
  s->putp += size;
}

struct ospf_packet *
ospf_packet_new (size_t size)
{
  struct ospf_packet *new;

  new = XCALLOC (MTYPE_OSPF_PACKET, sizeof (struct ospf_packet));
  new->s = stream_new (size);

  return new;
}

void
ospf_packet_free (struct ospf_packet *op)
{
  if (op->s)
    stream_free (op->s);

  XFREE (MTYPE_OSPF_PACKET, op);

  op = NULL;
}

struct ospf_fifo *
ospf_fifo_new ()
{
  struct ospf_fifo *new;

  new = XCALLOC (MTYPE_OSPF_FIFO, sizeof (struct ospf_fifo));
  return new;
}

/* Add new packet to fifo. */
void
ospf_fifo_push (struct ospf_fifo *fifo, struct ospf_packet *op)
{
  if (fifo->tail)
    fifo->tail->next = op;
  else
    fifo->head = op;

  fifo->tail = op;

  fifo->count++;
}

/* Delete first packet from fifo. */
struct ospf_packet *
ospf_fifo_pop (struct ospf_fifo *fifo)
{
  struct ospf_packet *op;

  op = fifo->head;

  if (op)
    {
      fifo->head = op->next;

      if (fifo->head == NULL)
	fifo->tail = NULL;

      fifo->count--;
    }

  return op;
}

/* Return first fifo entry. */
struct ospf_packet *
ospf_fifo_head (struct ospf_fifo *fifo)
{
  return fifo->head;
}

/* Flush ospf packet fifo. */
void
ospf_fifo_flush (struct ospf_fifo *fifo)
{
  struct ospf_packet *op;
  struct ospf_packet *next;

  for (op = fifo->head; op; op = next)
    {
      next = op->next;
      ospf_packet_free (op);
    }
  fifo->head = fifo->tail = NULL;
  fifo->count = 0;
}

/* Free ospf packet fifo. */
void
ospf_fifo_free (struct ospf_fifo *fifo)
{
  ospf_fifo_flush (fifo);

  XFREE (MTYPE_OSPF_FIFO, fifo);
}

void
ospf_packet_add (struct ospf_interface *oi, struct ospf_packet *op)
{
  /* Add packet to end of queue. */
  ospf_fifo_push (oi->obuf, op);

  /* Debug of packet fifo*/
  /* ospf_fifo_debug (oi->obuf); */
}

void
ospf_packet_delete (struct ospf_interface *oi)
{
  struct ospf_packet *op;
  
  op = ospf_fifo_pop (oi->obuf);

  if (op)
    ospf_packet_free (op);
}

struct stream *
ospf_stream_copy (struct stream *new, struct stream *s)
{
  new->endp = s->endp;
  new->putp = s->putp;
  new->getp = s->getp;

  memcpy (new->data, s->data, stream_get_endp (s));

  return new;
}

struct ospf_packet *
ospf_packet_dup (struct ospf_packet *op)
{
  struct ospf_packet *new;

  if (stream_get_endp(op->s) != op->length)
    zlog_warn ("ospf_packet_dup stream %ld ospf_packet %d size mismatch",
	       STREAM_SIZE(op->s), op->length);

  /* Reserve space for MD5 authentication that may be added later. */
  new = ospf_packet_new (stream_get_endp(op->s) + OSPF_AUTH_MD5_SIZE);
  ospf_stream_copy (new->s, op->s);

  new->dst = op->dst;
  new->length = op->length;

  return new;
}

int
ospf_packet_max (struct ospf_interface *oi)
{
  int max;

  if ( ospf_auth_type (oi) == OSPF_AUTH_CRYPTOGRAPHIC)
    max = oi->ifp->mtu - OSPF_AUTH_MD5_SIZE - 88;
  else
    max = oi->ifp->mtu - 88;

  return max;
}


int
ospf_check_md5_digest (struct ospf_interface *oi, struct stream *s,
                       u_int16_t length)
{
  void *ibuf;
  struct md5_ctx ctx;
  unsigned char digest[OSPF_AUTH_MD5_SIZE];
  unsigned char *pdigest;
  struct crypt_key *ck;
  struct ospf_header *ospfh;
  struct ospf_neighbor *nbr;
  

  ibuf = STREAM_PNT (s);
  ospfh = (struct ospf_header *) ibuf;

  /* Get pointer to the end of the packet. */
  pdigest = ibuf + length;

  /* Get secret key. */
  ck = ospf_crypt_key_lookup (OSPF_IF_PARAM (oi, auth_crypt),
			      ospfh->u.crypt.key_id);
  if (ck == NULL)
    {
      zlog_warn ("interface %s: ospf_check_md5 no key %d",
		 IF_NAME (oi), ospfh->u.crypt.key_id);
      return 0;
    }

  /* check crypto seqnum. */
  nbr = ospf_nbr_lookup_by_routerid (oi->nbrs, &ospfh->router_id);

  if (nbr && ntohl(nbr->crypt_seqnum) > ntohl(ospfh->u.crypt.crypt_seqnum))
    {
      zlog_warn ("interface %s: ospf_check_md5 bad sequence %d (expect %d)",
		 IF_NAME (oi),
		 ntohl(ospfh->u.crypt.crypt_seqnum),
		 ntohl(nbr->crypt_seqnum));
      return 0;
    }
      
  /* Generate a digest for the ospf packet - their digest + our digest. */
  md5_init_ctx (&ctx);
  md5_process_bytes (ibuf, length, &ctx);
  md5_process_bytes (ck->auth_key, OSPF_AUTH_MD5_SIZE, &ctx);
  md5_finish_ctx (&ctx, digest);

  /* compare the two */
  if (memcmp (pdigest, digest, OSPF_AUTH_MD5_SIZE))
    {
      zlog_warn ("interface %s: ospf_check_md5 checksum mismatch",
		 IF_NAME (oi));
      return 0;
    }

  /* save neighbor's crypt_seqnum */
  if (nbr)
    nbr->crypt_seqnum = ospfh->u.crypt.crypt_seqnum;
  return 1;
}

/* This function is called from ospf_write(), it will detect the
   authentication scheme and if it is MD5, it will change the sequence
   and update the MD5 digest. */
int
ospf_make_md5_digest (struct ospf_interface *oi, struct ospf_packet *op)
{
  struct ospf_header *ospfh;
  unsigned char digest[OSPF_AUTH_MD5_SIZE];
  struct md5_ctx ctx;
  void *ibuf;
  unsigned long oldputp;
  u_int32_t t;
  struct crypt_key *ck;
  char *auth_key;

  ibuf = STREAM_DATA (op->s);
  ospfh = (struct ospf_header *) ibuf;

  if (ntohs (ospfh->auth_type) != OSPF_AUTH_CRYPTOGRAPHIC)
    return 0;

  /* We do this here so when we dup a packet, we don't have to
     waste CPU rewriting other headers. */
  t = (time(NULL) & 0xFFFFFFFF);
  oi->crypt_seqnum = ( t > oi->crypt_seqnum ? t : oi->crypt_seqnum++);
  ospfh->u.crypt.crypt_seqnum = htonl (oi->crypt_seqnum); 

  /* Get MD5 Authentication key from auth_key list. */
  if (list_isempty (OSPF_IF_PARAM (oi, auth_crypt)))
    auth_key = "";
  else
    {
      ck = getdata (OSPF_IF_PARAM (oi, auth_crypt)->tail);
      auth_key = ck->auth_key;
    }

  /* Generate a digest for the entire packet + our secret key. */
  md5_init_ctx (&ctx);
  md5_process_bytes (ibuf, ntohs (ospfh->length), &ctx);
  md5_process_bytes (auth_key, OSPF_AUTH_MD5_SIZE, &ctx);
  md5_finish_ctx (&ctx, digest);

  /* Append md5 digest to the end of the stream. */
  oldputp = stream_get_putp (op->s);
  stream_set_putp (op->s, ntohs (ospfh->length));
  stream_put (op->s, digest, OSPF_AUTH_MD5_SIZE);
  stream_set_putp (op->s, oldputp);

  /* We do *NOT* increment the OSPF header length. */
  op->length = ntohs (ospfh->length) + OSPF_AUTH_MD5_SIZE;

  if (stream_get_endp(op->s) != op->length)
    zlog_warn("ospf_make_md5_digest: length mismatch stream %ld ospf_packet %d", stream_get_endp(op->s), op->length);

  return OSPF_AUTH_MD5_SIZE;
}


int
ospf_ls_req_timer (struct thread *thread)
{
  struct ospf_neighbor *nbr;

  nbr = THREAD_ARG (thread);
  nbr->t_ls_req = NULL;

  /* Send Link State Request. */
  if (ospf_ls_request_count (nbr))
    ospf_ls_req_send (nbr);

  /* Set Link State Request retransmission timer. */
  OSPF_NSM_TIMER_ON (nbr->t_ls_req, ospf_ls_req_timer, nbr->v_ls_req);

  return 0;
}

void
ospf_ls_req_event (struct ospf_neighbor *nbr)
{
  if (nbr->t_ls_req)
    {
      thread_cancel (nbr->t_ls_req);
      nbr->t_ls_req = NULL;
    }
  nbr->t_ls_req = thread_add_event (master, ospf_ls_req_timer, nbr, 0);
}

/* Cyclic timer function.  Fist registered in ospf_nbr_new () in
   ospf_neighbor.c  */
int
ospf_ls_upd_timer (struct thread *thread)
{
  struct ospf_neighbor *nbr;

  nbr = THREAD_ARG (thread);
  nbr->t_ls_upd = NULL;

  /* Send Link State Update. */
  if (ospf_ls_retransmit_count (nbr) > 0)
    {
      list update;
      struct ospf_lsdb *lsdb;
      int i;
      struct timeval now;
      int retransmit_interval;

      gettimeofday (&now, NULL);
      retransmit_interval = OSPF_IF_PARAM (nbr->oi, retransmit_interval);

      lsdb = &nbr->ls_rxmt;
      update = list_new ();

      for (i = OSPF_MIN_LSA; i < OSPF_MAX_LSA; i++)
	{
	  struct route_table *table = lsdb->type[i].db;
	  struct route_node *rn;
	  
	  for (rn = route_top (table); rn; rn = route_next (rn))
	    {
	      struct ospf_lsa *lsa;
	      
	      if ((lsa = rn->info) != NULL)
		/* Don't retransmit an LSA if we received it within
		  the last RxmtInterval seconds - this is to allow the
		  neighbour a chance to acknowledge the LSA as it may
		  have ben just received before the retransmit timer
		  fired.  This is a small tweak to what is in the RFC,
		  but it will cut out out a lot of retransmit traffic
		  - MAG */
		if (tv_cmp (tv_sub (now, lsa->tv_recv), 
			    int2tv (retransmit_interval)) >= 0)
		  listnode_add (update, rn->info);
	    }
	}

      if (listcount (update) > 0)
	ospf_ls_upd_send (nbr, update, OSPF_SEND_PACKET_DIRECT);
      list_delete (update);
    }

  /* Set LS Update retransmission timer. */
  OSPF_NSM_TIMER_ON (nbr->t_ls_upd, ospf_ls_upd_timer, nbr->v_ls_upd);

  return 0;
}

int
ospf_ls_ack_timer (struct thread *thread)
{
  struct ospf_interface *oi;

  oi = THREAD_ARG (thread);
  oi->t_ls_ack = NULL;

  /* Send Link State Acknowledgment. */