ripngd.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

     apply_mask_ipv6. */
  apply_mask_ipv6 (&p);

  /* Apply input filters. */
  ri = ifp->info;

  if (ri->list[RIPNG_FILTER_IN])
    {
      if (access_list_apply (ri->list[RIPNG_FILTER_IN], &p) == FILTER_DENY)
	{
	  if (IS_RIPNG_DEBUG_PACKET)
	    zlog_info ("RIPng %s/%d is filtered by distribute in",
		       inet6_ntop (&p.prefix), p.prefixlen);
	  return;
	}
    }
  if (ri->prefix[RIPNG_FILTER_IN])
    {
      if (prefix_list_apply (ri->prefix[RIPNG_FILTER_IN], &p) == PREFIX_DENY)
	{
	  if (IS_RIPNG_DEBUG_PACKET)
	    zlog_info ("RIPng %s/%d is filtered by prefix-list in",
		       inet6_ntop (&p.prefix), p.prefixlen);
	  return;
	}
    }

  /* Modify entry. */
  if (ri->routemap[RIPNG_FILTER_IN])
    {
      int ret;
      struct ripng_info newinfo;

      memset (&newinfo, 0, sizeof (struct ripng_info));
      newinfo.metric = rte->metric;

      ret = route_map_apply (ri->routemap[RIPNG_FILTER_IN], 
			     (struct prefix *)&p, RMAP_RIPNG, &newinfo);

      if (ret == RMAP_DENYMATCH)
	{
	  if (IS_RIPNG_DEBUG_PACKET)
	    zlog_info ("RIPng %s/%d is filtered by route-map in",
		       inet6_ntop (&p.prefix), p.prefixlen);
	  return;
	}

      rte->metric = newinfo.metric;
    }

  /* Set nexthop pointer. */
  if (ripng_nexthop->flag == RIPNG_NEXTHOP_ADDRESS)
    nexthop = &ripng_nexthop->address;
  else
    nexthop = &from->sin6_addr;

  /* Lookup RIPng routing table. */
  rp = route_node_get (ripng->table, (struct prefix *) &p);

  if (rp->info == NULL)
    {
      /* Now, check to see whether there is already an explicit route
	 for the destination prefix.  If there is no such route, add
	 this route to the routing table, unless the metric is
	 infinity (there is no point in adding a route which
	 unusable). */
      if (rte->metric != RIPNG_METRIC_INFINITY)
	{
	  rinfo = ripng_info_new ();
	  
	  /* - Setting the destination prefix and length to those in
	     the RTE. */
	  rp->info = rinfo;
	  rinfo->rp = rp;

	  /* - Setting the metric to the newly calculated metric (as
	     described above). */
	  rinfo->metric = rte->metric;
	  rinfo->tag = ntohs (rte->tag);

	  /* - Set the next hop address to be the address of the router
	     from which the datagram came or the next hop address
	     specified by a next hop RTE. */
	  IPV6_ADDR_COPY (&rinfo->nexthop, nexthop);
	  IPV6_ADDR_COPY (&rinfo->from, &from->sin6_addr);
	  rinfo->ifindex = ifp->ifindex;

	  /* - Initialize the timeout for the route.  If the
	     garbage-collection timer is running for this route, stop it. */
	  ripng_timeout_update (rinfo);

	  /* - Set the route change flag. */
	  rinfo->flags |= RIPNG_RTF_CHANGED;

	  /* - Signal the output process to trigger an update (see section
	     2.5). */
	  ripng_event (RIPNG_TRIGGERED_UPDATE, 0);

	  /* Finally, route goes into the kernel. */
	  rinfo->type = ZEBRA_ROUTE_RIPNG;
	  rinfo->sub_type = RIPNG_ROUTE_RTE;

	  ripng_zebra_ipv6_add (&p, &rinfo->nexthop, rinfo->ifindex);
	  rinfo->flags |= RIPNG_RTF_FIB;

	  /* Aggregate check. */
	  ripng_aggregate_increment (rp, rinfo);
	}
    }
  else
    {
      rinfo = rp->info;
	  
      /* If there is an existing route, compare the next hop address
	 to the address of the router from which the datagram came.
	 If this datagram is from the same router as the existing
	 route, reinitialize the timeout.  */
      same = (IN6_ARE_ADDR_EQUAL (&rinfo->from, &from->sin6_addr) 
	      && (rinfo->ifindex == ifp->ifindex));

      if (same)
	ripng_timeout_update (rinfo);

      /* Next, compare the metrics.  If the datagram is from the same
	 router as the existing route, and the new metric is different
	 than the old one; or, if the new metric is lower than the old
	 one; do the following actions: */
      if ((same && rinfo->metric != rte->metric) ||
	  rte->metric < rinfo->metric)
	{
	  /* - Adopt the route from the datagram.  That is, put the
	     new metric in, and adjust the next hop address (if
	     necessary). */
	  oldmetric = rinfo->metric;
	  rinfo->metric = rte->metric;
	  rinfo->tag = ntohs (rte->tag);

	  if (! IN6_ARE_ADDR_EQUAL (&rinfo->nexthop, nexthop))
	    {
	      ripng_zebra_ipv6_delete (&p, &rinfo->nexthop, rinfo->ifindex);
	      ripng_zebra_ipv6_add (&p, nexthop, ifp->ifindex);
	      rinfo->flags |= RIPNG_RTF_FIB;

	      IPV6_ADDR_COPY (&rinfo->nexthop, nexthop);
	    }
	  IPV6_ADDR_COPY (&rinfo->from, &from->sin6_addr);
	  rinfo->ifindex = ifp->ifindex;

	  /* - Set the route change flag and signal the output process
	     to trigger an update. */
	  rinfo->flags |= RIPNG_RTF_CHANGED;
	  ripng_event (RIPNG_TRIGGERED_UPDATE, 0);

	  /* - If the new metric is infinity, start the deletion
	     process (described above); */
	  if (rinfo->metric == RIPNG_METRIC_INFINITY)
	    {
	      /* If the new metric is infinity, the deletion process
		 begins for the route, which is no longer used for
		 routing packets.  Note that the deletion process is
		 started only when the metric is first set to
		 infinity.  If the metric was already infinity, then a
		 new deletion process is not started. */
	      if (oldmetric != RIPNG_METRIC_INFINITY)
		{
		  /* - The garbage-collection timer is set for 120 seconds. */
		  RIPNG_TIMER_ON (rinfo->t_garbage_collect, 
				  ripng_garbage_collect, ripng->garbage_time);
		  RIPNG_TIMER_OFF (rinfo->t_timeout);

		  /* - The metric for the route is set to 16
		     (infinity).  This causes the route to be removed
		     from service.*/
		  /* - The route change flag is to indicate that this
		     entry has been changed. */
		  /* - The output process is signalled to trigger a
                     response. */
		  ;  /* Above processes are already done previously. */
		}
	    }
	  else
	    {
	      /* otherwise, re-initialize the timeout. */
	      ripng_timeout_update (rinfo);

	      /* Should a new route to this network be established
		 while the garbage-collection timer is running, the
		 new route will replace the one that is about to be
		 deleted.  In this case the garbage-collection timer
		 must be cleared. */
	      RIPNG_TIMER_OFF (rinfo->t_garbage_collect);
	    }
	}
      /* Unlock tempolary lock of the route. */
      route_unlock_node (rp);
    }
}

/* Add redistributed route to RIPng table. */
void
ripng_redistribute_add (int type, int sub_type, struct prefix_ipv6 *p, 
			unsigned int ifindex)
{
  struct route_node *rp;
  struct ripng_info *rinfo;

  /* Redistribute route  */
  if (IN6_IS_ADDR_LINKLOCAL (&p->prefix))
    return;
  if (IN6_IS_ADDR_LOOPBACK (&p->prefix))
    return;

  rp = route_node_get (ripng->table, (struct prefix *) p);
  rinfo = rp->info;

  if (rinfo)
    {
      RIPNG_TIMER_OFF (rinfo->t_timeout);
      RIPNG_TIMER_OFF (rinfo->t_garbage_collect);
      route_unlock_node (rp);
    }
  else
    {
      rinfo = ripng_info_new ();
      ripng_aggregate_increment (rp, rinfo);
    }

  rinfo->type = type;
  rinfo->sub_type = sub_type;
  rinfo->ifindex = ifindex;
  rinfo->metric = 1;
  rinfo->flags |= RIPNG_RTF_FIB;

  rinfo->rp = rp;
  rp->info = rinfo;
}

/* Delete redistributed route to RIPng table. */
void
ripng_redistribute_delete (int type, int sub_type, struct prefix_ipv6 *p, 
			   unsigned int ifindex)
{
  struct route_node *rp;
  struct ripng_info *rinfo;

  if (IN6_IS_ADDR_LINKLOCAL (&p->prefix))
    return;
  if (IN6_IS_ADDR_LOOPBACK (&p->prefix))
    return;

  rp = route_node_lookup (ripng->table, (struct prefix *) p);

  if (rp)
    {
      rinfo = rp->info;

      if (rinfo != NULL
	  && rinfo->type == type 
	  && rinfo->sub_type == sub_type 
	  && rinfo->ifindex == ifindex)
	{
	  rp->info = NULL;

	  RIPNG_TIMER_OFF (rinfo->t_timeout);
	  RIPNG_TIMER_OFF (rinfo->t_garbage_collect);
	  
	  ripng_info_free (rinfo);

	  route_unlock_node (rp);
	}

      /* For unlock route_node_lookup (). */
      route_unlock_node (rp);
    }
}

/* Withdraw redistributed route. */
void
ripng_redistribute_withdraw (int type)
{
  struct route_node *rp;
  struct ripng_info *rinfo;

  for (rp = route_top (ripng->table); rp; rp = route_next (rp))
    if ((rinfo = rp->info) != NULL)
      {
	if (rinfo->type == type)
	  {
	    rp->info = NULL;

	    RIPNG_TIMER_OFF (rinfo->t_timeout);
	    RIPNG_TIMER_OFF (rinfo->t_garbage_collect);

	    ripng_info_free (rinfo);

	    route_unlock_node (rp);
	  }
      }
}

/* RIP routing information. */
void
ripng_response_process (struct ripng_packet *packet, int size, 
			struct sockaddr_in6 *from, struct interface *ifp,
			int hoplimit)
{
  caddr_t lim;
  struct rte *rte;
  struct ripng_nexthop nexthop;

  /* RFC2080 2.4.2  Response Messages:
   The Response must be ignored if it is not from the RIPng port.  */
  if (ntohs (from->sin6_port) != RIPNG_PORT_DEFAULT)
    {
      zlog_warn ("RIPng packet comes from non RIPng port %d from %s",
		 ntohs (from->sin6_port), inet6_ntop (&from->sin6_addr));
      return;
    }

  /* The datagram's IPv6 source address should be checked to see
   whether the datagram is from a valid neighbor; the source of the
   datagram must be a link-local address.  */
  if (! IN6_IS_ADDR_LINKLOCAL(&from->sin6_addr))
   {
      zlog_warn ("RIPng packet comes from non link local address %s",
		 inet6_ntop (&from->sin6_addr));
      return;
    }

  /* It is also worth checking to see whether the response is from one
   of the router's own addresses.  Interfaces on broadcast networks
   may receive copies of their own multicasts immediately.  If a
   router processes its own output as new input, confusion is likely,
   and such datagrams must be ignored. */
  if (ripng_lladdr_check (ifp, &from->sin6_addr))
    {
      zlog_warn ("RIPng packet comes from my own link local address %s",
		 inet6_ntop (&from->sin6_addr));
      return;
    }

  /* As an additional check, periodic advertisements must have their
   hop counts set to 255, and inbound, multicast packets sent from the
   RIPng port (i.e. periodic advertisement or triggered update
   packets) must be examined to ensure that the hop count is 255. */
  if (hoplimit >= 0 && hoplimit != 255)
    {
      zlog_warn ("RIPng packet comes with non 255 hop count %d from %s",
		 hoplimit, inet6_ntop (&from->sin6_addr));
      return;
    }

  /* Reset nexthop. */
  memset (&nexthop, 0, sizeof (struct ripng_nexthop));
  nexthop.flag = RIPNG_NEXTHOP_UNSPEC;

  /* Set RTE pointer. */
  rte = packet->rte;

  for (lim = ((caddr_t) packet) + size; (caddr_t) rte < lim; rte++) 
    {
      /* First of all, we have to check this RTE is next hop RTE or
         not.  Next hop RTE is completely different with normal RTE so
         we need special treatment. */
      if (rte->metric == RIPNG_METRIC_NEXTHOP)
	{
	  ripng_nexthop_rte (rte, from, &nexthop);
	  continue;
	}

      /* RTE information validation. */

      /* - is the destination prefix valid (e.g., not a multicast
         prefix and not a link-local address) A link-local address
         should never be present in an RTE. */
      if (IN6_IS_ADDR_MULTICAST (&rte->addr))
	{
	  zlog_warn ("Destination prefix is a multicast address %s/%d [%d]",
		     inet6_ntop (&rte->addr), rte->prefixlen, rte->metric);
	  continue;
	}
      if (IN6_IS_ADDR_LINKLOCAL (&rte->addr))
	{
	  zlog_warn ("Destination prefix is a link-local address %s/%d [%d]",
		     inet6_ntop (&rte->addr), rte->prefixlen, rte->metric);
	  continue;
	}
      if (IN6_IS_ADDR_LOOPBACK (&rte->addr))
	{
	  zlog_warn ("Destination prefix is a loopback address %s/%d [%d]",
		     inet6_ntop (&rte->addr), rte->prefixlen, rte->metric);
	  continue;
	}

      /* - is the prefix length valid (i.e., between 0 and 128,
         inclusive) */
      if (rte->prefixlen > 128)
	{
	  zlog_warn ("Invalid prefix length %s/%d from %s%%%s",
		     inet6_ntop (&rte->addr), rte->prefixlen,
		     inet6_ntop (&from->sin6_addr), ifp->name);
	  continue;
	}

      /* - is the metric valid (i.e., between 1 and 16, inclusive) */
      if (! (rte->metric >= 1 && rte->metric <= 16))
	{
	  zlog_warn ("Invalid metric %d from %s%%%s", rte->metric,
		     inet6_ntop (&from->sin6_addr), ifp->name);
	  continue;
	}

      /* Metric calculation. */
      rte->metric += ifp->metric;
      if (rte->metric > RIPNG_METRIC_INFINITY)
	rte->metric = RIPNG_METRIC_INFINITY;

      /* Routing table updates. */
      ripng_route_process (rte, from, &nexthop, ifp);
    }
}

/* Response to request message. */
void
ripng_request_process (struct ripng_packet *packet,int size, 
		       struct sockaddr_in6 *from, struct interface *ifp)
{
  caddr_t lim;
  struct rte *rte;
  struct prefix_ipv6 p;
  struct route_node *rp;
  struct ripng_info *rinfo;
  struct ripng_interface *ri;

  /* Check RIPng process is enabled on this interface. */
  ri = ifp->info;
  if (! ri->running)
    return;

  /* When passive interface is specified, suppress responses */
  if (ri->passive)
    return;

  lim = ((caddr_t) packet) + size;
  rte = packet->rte;

  /* The Request is processed entry by entry.  If there are no
     entries, no response is given. */
  if (lim == (caddr_t) rte)
    return;

  /* There is one special case.  If there is exactly one entry in the
     request, and it has a destination prefix of zero, a prefix length
     of zero, and a metric of infinity (i.e., 16), then this is a
     request to send the entire routing table.  In that case, a call
     is made to the output process to send the routing table to the
     requesting address/port. */
  if (lim == ((caddr_t) (rte + 1)) &&
      IN6_IS_ADDR_UNSPECIFIED (&rte->addr) &&
      rte->prefixlen == 0 &&
      rte->metric == RIPNG_METRIC_INFINITY)
    {	
      /* All route with split horizon */
      ripng_output_process (ifp, from, ripng_all_route, ripng_split_horizon);
    }
  else
    {
      /* Except for this special case, processing is quite simple.
	 Examine the list of RTEs in the Request one by one.  For each
	 entry, look up the destination in the router's routing
	 database and, if there is a route, put that route's metric in
	 the metric field of the RTE.  If there is no explicit route
	 to the specified destination, put infinity in the metric
	 field.  Once all the entries have been filled in, change the
	 command from Request to Response and send the datagram back
	 to the requestor. */
      memset (&p, 0, sizeof (struct prefix_ipv6));
      p.family = AF_INET6;

      for (; ((caddr_t) rte) < lim; rte++)
	{
	  p.prefix = rte->addr;
	  p.prefixlen = rte->prefixlen;
	  apply_mask_ipv6 (&p);
	  
	  rp = route_node_lookup (ripng->table, (struct prefix *) &p);

	  if (rp)
	    {
	      rinfo = rp->info;
	      rte->metric = rinfo->metric;
	      route_unlock_node (rp);
	    }
	  else
	    rte->metric = RIPNG_METRIC_INFINITY;
	}
      packet->command = RIPNG_RESPONSE;

      ripng_send_packet ((caddr_t) packet, size, from, ifp);
    }
}

/* First entry point of reading RIPng packet. */
int