Commit e86cfd41 authored by Ondrej Zajicek (work)'s avatar Ondrej Zajicek (work)
Browse files

KRT: Fix route learn scan when route changed 

When a kernel route changed, function krt_learn_scan() noticed that and
replaced the route in internal kernel FIB, but after that, function
krt_learn_prune() failed to propagate the new route to the nest, because
it confused the new route with the (removed) old best route and decided
that the best route did not changed.

Wow, the original code (and the bug) is almost 17 years old.
parent ea0a8be2

nest/route.h

+1 −1
Original line number Diff line number Diff line
@@ -223,8 +223,8 @@ typedef struct rte { 
    struct {				/* Routes generated by krt sync (both temporary and inherited ones) */

      s8 src;				/* Alleged route source (see krt.h) */

      u8 proto;				/* Kernel source protocol ID */

      u8 type;				/* Kernel route type */

      u8 seen;				/* Seen during last scan */

      u8 best;				/* Best route in network, propagated to core */

      u32 metric;			/* Kernel metric */

    } krt;

  } u;

sysdep/bsd/krt-sock.c

+2 −3
Original line number Diff line number Diff line
@@ -493,9 +493,8 @@ krt_read_route(struct ks_msg *msg, struct krt_proto *p, int scan) 
  e->net = net;

  e->u.krt.src = src;

  e->u.krt.proto = src2;



  /* These are probably too Linux-specific */

  e->u.krt.type = 0;

  e->u.krt.seen = 0;

  e->u.krt.best = 0;

  e->u.krt.metric = 0;



  if (scan)

sysdep/linux/netlink.c

+2 −1
Original line number Diff line number Diff line
@@ -1102,7 +1102,8 @@ nl_parse_route(struct nlmsghdr *h, int scan) 
  e->net = net;

  e->u.krt.src = src;

  e->u.krt.proto = i->rtm_protocol;

  e->u.krt.type = i->rtm_type;

  e->u.krt.seen = 0;

  e->u.krt.best = 0;

  e->u.krt.metric = 0;



  if (a[RTA_PRIORITY])

sysdep/unix/krt.c

+29 −17
Original line number Diff line number Diff line
@@ -417,46 +417,58 @@ again: 
      net *n = (net *) f;

      rte *e, **ee, *best, **pbest, *old_best;



      old_best = n->routes;

      /*

       * Note that old_best may be NULL even if there was an old best route in

       * the previous step, because it might be replaced in krt_learn_scan().

       * But in that case there is a new valid best route.

       */



      old_best = NULL;

      best = NULL;

      pbest = NULL;

      ee = &n->routes;

      while (e = *ee)

	{

	  if (e->u.krt.best)

	    old_best = e;



	  if (!e->u.krt.seen)

	    {

	      *ee = e->next;

	      rte_free(e);

	      continue;

	    }



	  if (!best || best->u.krt.metric > e->u.krt.metric)

	    {

	      best = e;

	      pbest = ee;

	    }



	  e->u.krt.seen = 0;

	  e->u.krt.best = 0;

	  ee = &e->next;

	}

      if (!n->routes)

	{

	  DBG("%I/%d: deleting\n", n->n.prefix, n->n.pxlen);

	  if (old_best)

	    {

	    krt_learn_announce_delete(p, n);

	      n->n.flags &= ~KRF_INSTALLED;

	    }



	  FIB_ITERATE_PUT(&fit, f);

	  fib_delete(fib, f);

	  goto again;

	}



      best->u.krt.best = 1;

      *pbest = best->next;

      best->next = n->routes;

      n->routes = best;

      if (best != old_best || !(n->n.flags & KRF_INSTALLED) || p->reload)



      if ((best != old_best) || p->reload)

	{

	  DBG("%I/%d: announcing (metric=%d)\n", n->n.prefix, n->n.pxlen, best->u.krt.metric);

	  krt_learn_announce_update(p, best);

	  n->n.flags |= KRF_INSTALLED;

	}

      else

	DBG("%I/%d: uptodate (metric=%d)\n", n->n.prefix, n->n.pxlen, best->u.krt.metric);
@@ -515,31 +527,31 @@ krt_learn_async(struct krt_proto *p, rte *e, int new) 
  best = n->routes;

  bestp = &n->routes;

  for(gg=&n->routes; g=*gg; gg=&g->next)

  {

    if (best->u.krt.metric > g->u.krt.metric)

      {

	best = g;

	bestp = gg;

      }



    g->u.krt.best = 0;

  }



  if (best)

    {

      best->u.krt.best = 1;

      *bestp = best->next;

      best->next = n->routes;

      n->routes = best;

    }



  if (best != old_best)

    {

      DBG("krt_learn_async: distributing change\n");

      if (best)

	{

	krt_learn_announce_update(p, best);

	  n->n.flags |= KRF_INSTALLED;

	}

      else

	{

	  n->routes = NULL;

	krt_learn_announce_delete(p, n);

	  n->n.flags &= ~KRF_INSTALLED;

	}

    }

}
@@ -564,7 +576,7 @@ krt_dump(struct proto *P) 
static void

krt_dump_attrs(rte *e)

{

  debug(" [m=%d,p=%d,t=%d]", e->u.krt.metric, e->u.krt.proto, e->u.krt.type);

  debug(" [m=%d,p=%d]", e->u.krt.metric, e->u.krt.proto);

}



#endif

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