/*
 *	Rest in pieces - RIP protocol
 *
 *	Copyright (c) 1998 Pavel Machek <pavel@ucw.cz>
 *
 *	Can be freely distributed and used under the terms of the GNU GPL.
 */

#define LOCAL_DEBUG

#include <string.h>
#include <stdlib.h>

#include "nest/bird.h"
#include "nest/iface.h"
#include "nest/protocol.h"
#include "nest/route.h"
#include "lib/socket.h"
#include "lib/resource.h"
#include "lib/lists.h"
#include "lib/timer.h"

#include "rip.h"

static void
rip_reply(struct proto *p)
{
#if 0
  P->listen->tbuf = "ACK!";
  sk_send_to( P->listen, 5, P->listen->faddr, P->listen->fport );
#endif
}

#define P_NAME "rip/unknown" /* FIXME */

/*
 * Output processing
 */

static void
rip_tx_err( sock *s, int err )
{
  struct rip_connection *c = s->data;
  struct proto *p = c->proto;
  log( L_ERR "Unexpected error at rip transmit: %m" );
}

static void
rip_tx( sock *s )
{
  struct rip_interface *rif = s->data;
  struct rip_connection *c = rif->busy;
  struct proto *p = c->proto;
  struct rip_packet *packet = (void *) s->tbuf;
  int i;

  do {

    if (c->done) {
      DBG( "Looks like I'm" );
      c->rif->busy = NULL;
      rem_node(NODE c);
      mb_free(c);
      DBG( " done\n" );
      return;
    }

    if (c->done) {
      DBG( "looks like I'm done!\n" );
      return;
    }

    DBG( "Preparing packet to send: " );

    packet->heading.command = RIPCMD_RESPONSE;
    packet->heading.version = RIP_V2;
    packet->heading.unused  = 0;

    i = 0;
    FIB_ITERATE_START(&P->rtable, &c->iter, z) {
      struct rip_entry *e = (struct rip_entry *) z;
      DBG( "." );
      packet->block[i].family  = htons( 2 ); /* AF_INET */
      packet->block[i].tag     = htons( 0 ); /* FIXME: What should I set it to? */
      packet->block[i].network = e->n.prefix;
      packet->block[i].netmask = ipa_mkmask( e->n.pxlen );
      packet->block[i].nexthop = IPA_NONE; /* FIXME: How should I set it? */
      packet->block[i].metric  = htonl( 1+ (e->metric?:1) );
      if (ipa_equal(e->whotoldme, s->daddr)) {
	DBG( "(split horizont)" );
	/* FIXME: should we do it in all cases? */
	packet->block[i].metric = P->infinity;
      }
      ipa_hton( packet->block[i].network );
      ipa_hton( packet->block[i].netmask );
      ipa_hton( packet->block[i].nexthop );

      if (i++ == 25) {
	FIB_ITERATE_PUT(&c->iter, z);
	goto break_loop;
      }
    } FIB_ITERATE_END(z);
    c->done = 1;

  break_loop:

    DBG( ", sending %d blocks, ", i );

    if (ipa_nonzero(c->daddr))
      i = sk_send_to( s, sizeof( struct rip_packet_heading ) + i*sizeof( struct rip_block ), c->daddr, c->dport );
    else
      i = sk_send( s, sizeof( struct rip_packet_heading ) + i*sizeof( struct rip_block ) );

    DBG( "it wants more\n" );
  
  } while (i>0);
  
  if (i<0) rip_tx_err( s, i );
  DBG( "blocked\n" );
}

static void
rip_sendto( struct proto *p, ip_addr daddr, int dport, struct rip_interface *rif )
{
  struct iface *iface = rif->iface;
  struct rip_connection *c = mb_alloc( p->pool, sizeof( struct rip_connection ));
  static int num = 0;

  if (rif->busy) {
    log (L_WARN "Interface %s is much too slow, dropping request", iface->name);
    return;
  }
  rif->busy = c;
  
  c->addr = daddr;
  c->proto = p;
  c->num = num++;
  c->rif = rif;

  c->dport = dport;
  c->daddr = daddr;
  if (c->rif->sock->data != rif)
    bug("not enough send magic");
#if 0
  if (sk_open(c->send)<0) {
    log( L_ERR "Could not open socket for data send to %I:%d on %s", daddr, dport, rif->iface->name );
    return;
  }
#endif

  c->done = 0;
  fit_init( &c->iter, &P->rtable );
  add_head( &P->connections, NODE c );
  debug( "Sending my routing table to %I:%d on %s\n", daddr, dport, rif->iface->name );

  rip_tx(c->rif->sock);
}

struct rip_interface*
find_interface(struct proto *p, struct iface *what)
{
  struct rip_interface *i;

  WALK_LIST (i, P->interfaces)
    if (i->iface == what)
      return i;
  return NULL;
}

/*
 * Input processing
 */

static int
process_authentication( struct proto *p, struct rip_block *block )
{
  /* FIXME: Should do md5 authentication */
  return 0;
}

/* Let main routing table know about our new entry */
static void
advertise_entry( struct proto *p, struct rip_block *b, ip_addr whotoldme )
{
  rta *a, A;
  rte *r;
  net *n;
  neighbor *neighbor;
  struct rip_interface *i;

  bzero(&A, sizeof(A));
  A.proto = p;
  A.source = RTS_RIP;
  A.scope = SCOPE_UNIVERSE;
  A.cast = RTC_UNICAST;
  A.dest = RTD_ROUTER;
  A.tos = 0;
  A.flags = 0;
  A.gw = ipa_nonzero(b->nexthop) ? b->nexthop : whotoldme;
  A.from = whotoldme;
  
  neighbor = neigh_find( p, &A.gw, 0 );
  if (!neighbor) {
    log( L_ERR "%I asked me to route %I/%I using not-neighbor %I.", A.from, b->network, b->netmask, A.gw );
    return;
  }

  A.iface = neighbor->iface;
  if (!(i = neighbor->data)) {
    i = neighbor->data = find_interface(p, A.iface);
  }
  /* set to: interface of nexthop */
  a = rta_lookup(&A);
  n = net_get( &master_table, 0, b->network, ipa_mklen( b->netmask )); /* FIXME: should verify that it really is netmask */
  r = rte_get_temp(a);
  r->u.rip.metric = ntohl(b->metric) + i->metric;
  if (r->u.rip.metric > P->infinity) r->u.rip.metric = P->infinity;
  r->u.rip.tag = ntohl(b->tag);
  r->net = n;
  r->pflags = 0; /* Here go my flags */
  rte_update( n, p, r );
  DBG( "done\n" );
}

static void
process_block( struct proto *p, struct rip_block *block, ip_addr whotoldme )
{
  struct rip_entry *e;
  int metric = ntohl( block->metric );
  ip_addr network = block->network;

  CHK_MAGIC;
  if ((!metric) || (metric > P->infinity)) {
    log( L_WARN "Got metric %d from %I", metric, whotoldme );
    return;
  }

  /* FIXME: Check if destination looks valid - ie not net 0 or 127 */

  debug( "block: %I tells me: %I/%I available, metric %d... ", whotoldme, network, block->netmask, metric );

  advertise_entry( p, block, whotoldme );
}

#define BAD( x ) { log( L_WARN "RIP/%s: " x, P_NAME ); return 1; }

static int
rip_process_packet( struct proto *p, struct rip_packet *packet, int num, ip_addr whotoldme, int port )
{
  int i;
  int native_class = 0;

  switch( packet->heading.version ) {
  case RIP_V1: DBG( "Rip1: " ); break;
  case RIP_V2: DBG( "Rip2: " ); break;
  default: BAD( "Unknown version" );
  }

  switch( packet->heading.command ) {
  case RIPCMD_REQUEST: DBG( "Asked to send my routing table\n" ); 
    /* FIXME: should have configurable: ignore always, honour to neighbours, honour always. FIXME: use one global socket for these. FIXME: synchronization - if two ask me at same time */
    	  rip_sendto( p, whotoldme, port, NULL ); /* no broadcast */
          break;
  case RIPCMD_RESPONSE: DBG( "*** Rtable from %I\n", whotoldme ); 
          if (port != P->port) {
	    log( L_ERR "%I send me routing info from port %d", whotoldme, port );
#if 0
	    return 0;
#else
	    log( L_ERR "...ignoring" );
#endif
	  }

	  if (!neigh_find( p, &whotoldme, 0 )) {
	    log( L_ERR "%I send me routing info but he is not my neighbour", whotoldme );
	    return 0;
	  }

	  /* FIXME: Should check if it is not my own packet */

          for (i=0; i<num; i++) {
	    struct rip_block *block = &packet->block[i];
	    if (block->family == 0xffff)
	      if (!i) {
		if (process_authentication(p, block))
		  BAD( "Authentication failed" );
	      } else BAD( "Authentication is not the first!" );
	    ipa_ntoh( block->network );
	    ipa_ntoh( block->netmask );
	    ipa_ntoh( block->nexthop );
	    if (packet->heading.version == RIP_V1) {
	      block->netmask = block->network; /* MJ: why are macros like this?! */
	      ipa_class_mask( block->netmask );
	    }
	    process_block( p, block, whotoldme );
	  }
          break;
  case RIPCMD_TRACEON:
  case RIPCMD_TRACEOFF: BAD( "I was asked for traceon/traceoff" );
  case 5: BAD( "Some Sun extension around here" );
  default: BAD( "Unknown command" );
  }

  rip_reply(p);
  return 0;
}

static int
rip_rx(sock *s, int size)
{
  struct rip_interface *i = s->data;
  struct proto *p = i->proto;
  int num;

  CHK_MAGIC;
  DBG( "RIP: message came: %d bytes\n", size );
  size -= sizeof( struct rip_packet_heading );
  if (size < 0) BAD( "Too small packet" );
  if (size % sizeof( struct rip_block )) BAD( "Odd sized packet" );
  num = size / sizeof( struct rip_block );
  if (num>25) BAD( "Too many blocks" );

  rip_process_packet( p, (struct rip_packet *) s->rbuf, num, s->faddr, s->fport );
  return 1;
}

/*
 * Interface to rest of bird
 */

static void
rip_dump_entry( struct rip_entry *e )
{
  debug( "%I told me %d/%d ago: to %I/%d go via %I, metric %d ", 
  e->whotoldme, e->updated-now, e->changed-now, e->n.prefix, e->n.pxlen, e->nexthop, e->metric );
  if (e->flags & RIP_F_EXTERNAL) debug( "[external]" );
  debug( "\n" );
}

static void
rip_timer(timer *t)
{
  struct proto *p = t->data;
  struct rip_entry *e, *et;

  CHK_MAGIC;
  DBG( "RIP: tick tock\n" );
  
  WALK_LIST_DELSAFE( e, et, P->garbage ) {
    rte *rte;
    rte = SKIP_BACK( struct rte, u.rip.garbage, e );
    DBG( "Garbage: " ); rte_dump( rte );

    if (now - rte->lastmod > P->garbage_time) {
      debug( "RIP: entry is too old: " ); rte_dump( rte );
      rte_discard(rte);
    }
  }

  DBG( "RIP: Broadcasting routing tables\n" );
  {
    struct rip_interface *rif;

    WALK_LIST( rif, P->interfaces ) {
      struct iface *iface = rif->iface;

      if (rif->patt->mode == IM_QUIET)
	continue;

      if (!iface) continue;
      if (!(iface->flags & IF_UP)) continue;
      if (iface->flags & (IF_IGNORE | IF_LOOPBACK)) continue;

      rip_sendto( p, IPA_NONE, 0, rif );
    }
  }

  DBG( "RIP: tick tock done\n" );
}

static int
rip_start(struct proto *p)
{
  struct rip_interface *rif;
  DBG( "RIP: starting instance...\n" );

  P->magic = RIP_MAGIC;
  fib_init( &P->rtable, p->pool, sizeof( struct rip_entry ), 0, NULL );
  init_list( &P->connections );
  init_list( &P->garbage );
  init_list( &P->interfaces );
  P->timer = tm_new( p->pool );
  P->timer->data = p;
  P->timer->randomize = 5;
  P->timer->recurrent = P->period; 
  P->timer->hook = rip_timer;
  tm_start( P->timer, 5 );
  rif = new_iface(p, NULL, 0);	/* Initialize dummy interface */
  add_head( &P->interfaces, NODE rif );
  CHK_MAGIC;

  DBG( "RIP: ...done\n");
  return PS_UP;
}

static struct proto *
rip_init(struct proto_config *cfg)
{
  struct proto *p = proto_new(cfg, sizeof(struct proto));

  return p;
}

static void
rip_dump(struct proto *p)
{
  int i;
  node *w, *e;
  struct rip_interface *rif;
  i = 0;
  WALK_LIST( w, P->connections ) {
    struct rip_connection *n = (void *) w;
    debug( "RIP: connection #%d: %I\n", n->num, n->addr );
  }
  i = 0;
  FIB_WALK( &P->rtable, e ) {
    debug( "RIP: entry #%d: ", i++ );
    rip_dump_entry( E );
  } FIB_WALK_END;
  i = 0;
  WALK_LIST( rif, P->interfaces ) {
    debug( "RIP: interface #%d: %s, %I, busy = %x\n", i++, rif->iface?rif->iface->name:"(dummy)", rif->sock->daddr, rif->busy );
  }
}

static int
rip_want_this_if(struct rip_interface *iface)
{
  return 1;
}

static void
kill_iface(struct proto *p, struct rip_interface *i)
{
  DBG( "RIP: Interface %s disappeared\n", i->iface->name);
  rfree(i->sock);
  mb_free(i);
}

/*
 * new maybe null if we are creating initial send socket 
 */
struct rip_interface *
new_iface(struct proto *p, struct iface *new, unsigned long flags)
{
  struct rip_interface *rif;
  int want_multicast;

  rif = mb_alloc(p->pool, sizeof( struct rip_interface ));
  rif->iface = new;
  rif->proto = p;
  rif->busy = NULL;

  want_multicast = 0 && (flags & IF_MULTICAST);
  /* FIXME: should have config option to disable this one */
  /* FIXME: lookup multicasts over unnumbered links */

  rif->sock = sk_new( p->pool );
  rif->sock->type = want_multicast?SK_UDP_MC:SK_UDP;
  rif->sock->sport = P->port;
  rif->sock->rx_hook = rip_rx;
  rif->sock->data = rif;
  rif->sock->rbsize = 10240;
  rif->sock->iface = new;		/* Automagically works for dummy interface */
  rif->sock->tbuf = mb_alloc( p->pool, sizeof( struct rip_packet ));
  rif->sock->tx_hook = rip_tx;
  rif->sock->err_hook = rip_tx_err;
  rif->sock->daddr = IPA_NONE;
  rif->sock->dport = P->port;
  rif->sock->ttl = 1; /* FIXME: care must be taken not to send requested responses from this socket */

  if (want_multicast)
    rif->sock->daddr = ipa_from_u32(0x7f000001); /* FIXME: must lookup address in rfc's */
  if (flags & IF_BROADCAST)
    rif->sock->daddr = new->brd;
  if (flags & IF_UNNUMBERED)
    rif->sock->daddr = new->opposite;

  if (!ipa_nonzero(rif->sock->daddr))
    log( L_WARN "RIP: interface %s is too strange for me", rif->iface ? rif->iface->name : "(dummy)" );

  if (sk_open(rif->sock)<0)
    die( "RIP/%s: could not listen on %s", P_NAME, rif->iface ? rif->iface->name : "(dummy)" );
  /* FIXME: Should not be fatal, since the interface might have gone */
  
  return rif;
}

static void
rip_if_notify(struct proto *p, unsigned c, struct iface *new, struct iface *old)
{
  DBG( "RIP: if notify\n" );
  if (old) {
    struct rip_interface *i;
    i = find_interface(p, old);
    if (i) {
      rem_node(NODE i);
      kill_iface(p, i);
    }
  }
  if (new) {
    struct rip_interface *rif;
    struct iface_patt *k = iface_patt_match(&P->iface_list, new);

    if (!k) return; /* We are not interested in this interface */
    DBG("adding interface %s\n", new->name );
    rif = new_iface(p, new, new->flags);
    rif->patt = (void *) k;
    add_head( &P->interfaces, NODE rif );
  }
}

static void
rip_rt_notify(struct proto *p, struct network *net, struct rte *new, struct rte *old)
{
  CHK_MAGIC;

  if (old) {
    struct rip_entry *e = fib_find( &P->rtable, &net->n.prefix, net->n.pxlen );
    if (!e)
      log( L_BUG "Deleting nonexistent entry?!" );
    fib_delete( &P->rtable, e );
  }

  if (new) {
    struct rip_entry *e;
    if (fib_find( &P->rtable, &net->n.prefix, net->n.pxlen ))
      log( L_BUG "Inserting entry which is already there?" );
    e = fib_get( &P->rtable, &net->n.prefix, net->n.pxlen );

    e->nexthop = new->attrs->gw;
    e->tag = new->u.rip.tag;
    e->metric = new->u.rip.metric;
    e->whotoldme = new->attrs->from;
    e->updated = e->changed = now;
    e->flags = 0;
  }
}

static int
rip_rte_better(struct rte *new, struct rte *old)
{
  if (old->u.rip.metric < new->u.rip.metric)
    return 0;

  if (old->u.rip.metric > new->u.rip.metric)
    return 1;

#define old_metric_is_much_older_than_new_metric 0
  if ((old->u.rip.metric == new->u.rip.metric) && (old_metric_is_much_older_than_new_metric))
    return 1;

  return 0;
}

static int
rip_rta_same(rta *a, rta *b)
{
  /* As we have no specific data in rta, they are always the same */
  return 1;
}

static void
rip_rte_insert(net *net, rte *rte)
{
  struct proto *p = rte->attrs->proto;
  add_head( &P->garbage, &rte->u.rip.garbage );
}

static void
rip_rte_remove(net *net, rte *rte)
{
  struct proto *p = rte->attrs->proto;
  rem_node( &rte->u.rip.garbage );
}

void
rip_init_instance(struct proto *p)
{
  p->preference = DEF_PREF_RIP;
  p->if_notify = rip_if_notify;
  p->rt_notify = rip_rt_notify;
  p->rte_better = rip_rte_better;
  p->rta_same = rip_rta_same;
  p->rte_insert = rip_rte_insert;
  p->rte_remove = rip_rte_remove;

  P->infinity	= 16;
  P->port	= 520;
  P->period	= 30;
  P->garbage_time = 120+180;

  init_list(&P->iface_list);
}

static void
rip_preconfig(struct protocol *x, struct config *c)
{
  DBG( "RIP: preconfig\n" );
}

static void
rip_postconfig(struct proto_config *c)
{
}

struct protocol proto_rip = {
  name: "RIP",
  preconfig: rip_preconfig,
  postconfig: rip_postconfig,

  init: rip_init,
  dump: rip_dump,
  start: rip_start,
};