Fixes some problems in pipes.

For transparent pipes, loop detection works correctly now.
Pipes are now more symmetric - in both directions filtering
is done in do_rte_announce().

nest/rt-table.c

@@ -403,6 +403,26 @@ rte_recalculate(rtable *table, net *net, struct proto *p, struct proto *src, rte
     {
       if (old->attrs->proto == src)
 	{
+	  /* If there is the same route in the routing table but from
+	   * a different sender, then there are two paths from the
+	   * source protocol to this routing table through transparent
+	   * pipes, which is not allowed.
+	   *
+	   * We log that and ignore the route. If it is withdraw, we
+	   * ignore it completely (there might be 'spurious withdraws',
+	   * see FIXME in do_rte_announce())
+	   */
+	  if (old->sender != p)
+	    {
+	      if (new)
+		{
+		  log(L_ERR "Pipe collision detected when sending %I/%d to table %s",
+		      net->n.prefix, net->n.pxlen, table->name);
+		  rte_free_quick(new);
+		}
+	      return;
+	    }
+
 	  if (new && rte_same(old, new))
 	    {
 	      /* No changes, ignore the new route */
@@ -597,11 +617,12 @@ rte_update(rtable *table, net *net, struct proto *p, struct proto *src, rte *new
       new->sender = p;
       struct filter *filter = p->in_filter;
 
-	/* Do not filter routes going to the secondary side of the pipe, 
-	   that should only go through export filter.
-	   FIXME Make a better check whether p is really a pipe. */
-      if (p->table != table)
+      /* Do not filter routes going through the pipe, 
+	 they are filtered in the export filter only. */
+#ifdef CONFIG_PIPE
+      if (p->proto == &proto_pipe)
 	filter = FILTER_ACCEPT;
+#endif
 
       p->stats.imp_updates_received++;
       if (!rte_validate(new))

proto/pipe/pipe.c

@@ -31,7 +31,7 @@
 #include "pipe.h"
 
 static void
-pipe_send(struct pipe_proto *p, rtable *dest, net *n, rte *new, rte *old, ea_list *attrs)
+pipe_send(struct pipe_proto *p, rtable *src_table, rtable *dest, net *n, rte *new, rte *old, ea_list *attrs)
 {
   struct proto *src;
   net *nn;
@@ -80,9 +80,9 @@ pipe_send(struct pipe_proto *p, rtable *dest, net *n, rte *new, rte *old, ea_lis
       src = old->attrs->proto;
     }
 
-  dest->pipe_busy = 1;
+  src_table->pipe_busy = 1;
   rte_update(dest, nn, &p->p, (p->mode == PIPE_OPAQUE) ? &p->p : src, e);
-  dest->pipe_busy = 0;
+  src_table->pipe_busy = 0;
 }
 
 static void
@@ -91,7 +91,7 @@ pipe_rt_notify_pri(struct proto *P, net *net, rte *new, rte *old, ea_list *attrs
   struct pipe_proto *p = (struct pipe_proto *) P;
 
   DBG("PIPE %c> %I/%d\n", (new ? '+' : '-'), net->n.prefix, net->n.pxlen);
-  pipe_send(p, p->peer, net, new, old, attrs);
+  pipe_send(p, p->p.table, p->peer, net, new, old, attrs);
 }
 
 static void
@@ -100,7 +100,7 @@ pipe_rt_notify_sec(struct proto *P, net *net, rte *new, rte *old, ea_list *attrs
   struct pipe_proto *p = ((struct pipe_proto *) P)->phantom;
 
   DBG("PIPE %c< %I/%d\n", (new ? '+' : '-'), net->n.prefix, net->n.pxlen);
-  pipe_send(p, p->p.table, net, new, old, attrs);
+  pipe_send(p, p->peer, p->p.table, net, new, old, attrs);
 }
 
 static int
@@ -134,7 +134,20 @@ pipe_start(struct proto *P)
   ph->p.rt_notify = pipe_rt_notify_sec;
   ph->p.proto_state = PS_UP;
   ph->p.core_state = ph->p.core_goal = FS_HAPPY;
-  ph->p.in_filter = ph->p.out_filter = FILTER_ACCEPT;	/* We do all filtering on the local end */
+
+  /*
+   *  Routes should be filtered in the do_rte_announce() (export
+   *  filter for protocols). Reverse direction is handled by putting
+   *  specified import filter to out_filter field of the phantom
+   *  protocol.
+   *
+   *  in_filter fields are not important, there is an exception in
+   *  rte_update() to ignore it for pipes. We cannot just set
+   *  P->in_filter to FILTER_ACCEPT, because that would break other
+   *  things (reconfiguration, show-protocols command).
+   */
+  ph->p.in_filter = FILTER_ACCEPT;
+  ph->p.out_filter = P->in_filter;
 
   /*
    *  Connect the phantom protocol to the peer routing table, but