/*
 *	BIRD -- OSPF
 *
 *	(c) 1999 - 2003 Ondrej Filip <feela@network.cz>
 *
 *	Can be freely distributed and used under the terms of the GNU GPL.
 */

#include "ospf.h"

void
fill_ospf_pkt_hdr (struct ospf_iface *ifa, void *buf, u8 h_type)
{
  struct ospf_packet *pkt;
  struct proto *p;

  p = (struct proto *) (ifa->proto);

  pkt = (struct ospf_packet *) buf;

  pkt->version = OSPF_VERSION;

  pkt->type = h_type;

  pkt->routerid = htonl (p->cf->global->router_id);
  pkt->areaid = htonl (ifa->an);
  pkt->autype = htons (ifa->autype);
  pkt->checksum = 0;
}

void
ospf_tx_authenticate (struct ospf_iface *ifa, struct ospf_packet *pkt)
{
  int i;
  pkt->autype = htons (ifa->autype);
  memcpy (pkt->authetication, ifa->aukey, 8);
  return;
}

int
ospf_rx_authenticate (struct ospf_iface *ifa, struct ospf_packet *pkt)
{
  int i;
  if (pkt->autype != htons (ifa->autype))
    return 0;
  if (ifa->autype == AU_NONE)
    return 1;
  if (ifa->autype == AU_SIMPLE)
    {
      for (i = 0; i < 8; i++)
	{
	  if (pkt->authetication[i] != ifa->aukey[i])
	    return 0;
	}
      return 1;
    }
  return 0;
}

void
ospf_pkt_finalize (struct ospf_iface *ifa, struct ospf_packet *pkt)
{

  ospf_tx_authenticate (ifa, pkt);

  /* Count checksum */
  pkt->checksum = ipsum_calculate (pkt, sizeof (struct ospf_packet) - 8,
				   (pkt + 1),
				   ntohs (pkt->length) -
				   sizeof (struct ospf_packet), NULL);
}

/**
 * ospf_rx_hook
 * @sk: socket we received the packet. Its ignored.
 * @size: size of the packet
 *
 * This is the entry point for messages from neighbors. Many checks (like
 * authentication, checksums, size) are done before the packet is passed to
 * non generic functions.
 */
int
ospf_rx_hook (sock * sk, int size)
{
#ifndef IPV6
  struct ospf_packet *ps;
  struct ospf_iface *ifa = (struct ospf_iface *) (sk->data);
  struct proto *p = (struct proto *) (ifa->proto);
  int i;
  u8 *pu8;

  if (ifa->stub)
    return (1);

  DBG ("%s: RX_Hook called on interface %s.\n", p->name, sk->iface->name);

  ps = (struct ospf_packet *) ipv4_skip_header (sk->rbuf, &size);
  if (ps == NULL)
    {
      log ("%s: Bad OSPF packet received: bad IP header", p->name);
      log ("%s: Discarding", p->name);
      return (1);
    }

  if ((unsigned) size < sizeof (struct ospf_packet))
    {
      log ("%s: Bad OSPF packet received: too short (%u bytes)", p->name,
	   size);
      log ("%s: Discarding", p->name);
      return (1);
    }

  if ((ntohs (ps->length) != size) || (size != (4 * (size / 4))))
    {
      log ("%s: Bad OSPF packet received: size field does not match",
	   p->name);
      log ("%s: Discarding", p->name);
      return (1);
    }

  if (ps->version != OSPF_VERSION)
    {
      log ("%s: Bad OSPF packet received: version %u", p->name, ps->version);
      log ("%s: Discarding", p->name);
      return (1);
    }

  if (!ipsum_verify (ps, 16, (void *) ps + sizeof (struct ospf_packet),
		     ntohs (ps->length) - sizeof (struct ospf_packet), NULL))
    {
      log ("%s: Bad OSPF packet received: bad checksum", p->name);
      log ("%s: Discarding", p->name);
      return (1);
    }

  if (!ospf_rx_authenticate (ifa, ps))
    {
      log ("%s: Bad OSPF packet received: bad password", p->name);
      return (1);
    }

  if (ntohl (ps->areaid) != ifa->an)
    {
      log ("%s: Bad OSPF packet received: other area %ld", p->name,
	   ps->areaid);
      log ("%s: Discarding", p->name);
      return (1);
    }

  if (ntohl (ps->routerid) == p->cf->global->router_id)
    {
      log ("%s: Bad OSPF packet received: received my own router ID!",
	   p->name);
      log ("%s: Discarding", p->name);
      return (1);
    }

  if (ntohl (ps->routerid) == 0)
    {
      log ("%s: Bad OSPF packet received: Id 0.0.0.0 is not allowed.",
	   p->name);
      log ("%s: Discarding", p->name);
      return (1);
    }

  /* Dump packet 
     pu8=(u8 *)(sk->rbuf+5*4);
     for(i=0;i<ntohs(ps->length);i+=4)
     DBG("%s: received %u,%u,%u,%u\n",p->name, pu8[i+0], pu8[i+1], pu8[i+2],
     pu8[i+3]);
     DBG("%s: received size: %u\n",p->name,size);
   */

  switch (ps->type)
    {
    case HELLO_P:
      DBG ("%s: Hello received.\n", p->name);
      ospf_hello_receive((struct ospf_hello_packet *) ps, ifa, size,
		     sk->faddr);
      break;
    case DBDES_P:
      DBG ("%s: Database description received.\n", p->name);
      ospf_dbdes_rx ((struct ospf_dbdes_packet *) ps, p, ifa, size);
      break;
    case LSREQ_P:
      DBG ("%s: Link state request received.\n", p->name);
      ospf_lsreq_receive((struct ospf_lsreq_packet *) ps, ifa, size);
      break;
    case LSUPD_P:
      DBG ("%s: Link state update received.\n", p->name);
      ospf_lsupd_rx ((struct ospf_lsupd_packet *) ps, p, ifa, size);
      break;
    case LSACK_P:
      DBG ("%s: Link state ack received.\n", p->name);
      ospf_lsack_receive((struct ospf_lsack_packet *) ps, ifa, size);
      break;
    default:
      log ("%s: Bad packet received: wrong type %u", p->name, ps->type);
      log ("%s: Discarding\n", p->name);
      return (1);
    };
#else
#error RX_Hook does not work for IPv6 now.
#endif
  return (1);
}

void
ospf_tx_hook (sock * sk)
{
  struct ospf_iface *ifa;
  struct proto *p;

  ifa = (struct ospf_iface *) (sk->data);

  p = (struct proto *) (ifa->proto);
  DBG ("%s: TX_Hook called on interface %s\n", p->name, sk->iface->name);
}

void
ospf_err_hook (sock * sk, int err)
{
  struct ospf_iface *ifa;
  struct proto *p;

  ifa = (struct ospf_iface *) (sk->data);

  p = (struct proto *) (ifa->proto);
  DBG ("%s: Err_Hook called on interface %s\n", p->name, sk->iface->name);
}

void
sk_send_to_agt (sock * sk, u16 len, struct ospf_iface *ifa, u8 state)
{
  struct ospf_neighbor *n;

  WALK_LIST (NODE n, ifa->neigh_list) if (n->state >= state)
    sk_send_to (sk, len, n->ip, OSPF_PROTO);
}

void
sk_send_to_bdr (sock * sk, u16 len, struct ospf_iface *ifa)
{
  struct ospf_neighbor *n;

  if (ipa_compare (ifa->drip, ipa_from_u32 (0)) != 0)
    sk_send_to (sk, len, ifa->drip, OSPF_PROTO);
  if (ipa_compare (ifa->bdrip, ipa_from_u32 (0)) != 0)
    sk_send_to (sk, len, ifa->bdrip, OSPF_PROTO);
}