3 files changed, 26 insertions, 15 deletions
diff --git a/proto/pipe/config.Y b/proto/pipe/config.Y
index 1202c169..c869de9f 100644
--- a/proto/pipe/config.Y
+++ b/proto/pipe/config.Y
@@ -16,7 +16,7 @@ CF_DEFINES
 
 CF_DECLS
 
-CF_KEYWORDS(PIPE, PEER, TABLE)
+CF_KEYWORDS(PIPE, PEER, TABLE, MAX, GENERATION)
 
 CF_GRAMMAR
 
@@ -25,6 +25,7 @@ proto: pipe_proto '}' { this_channel = NULL; }  ;
 pipe_proto_start: proto_start PIPE
 {
   this_proto = proto_config_new(&proto_pipe, $1);
+  PIPE_CFG->max_generation = 16;
 }
 proto_name
 {
@@ -41,6 +42,10 @@ pipe_proto:
  | pipe_proto proto_item ';'
  | pipe_proto channel_item_ ';'
  | pipe_proto PEER TABLE rtable ';' { PIPE_CFG->peer = $4; }
+ | pipe_proto MAX GENERATION expr ';' {
+    if (($4 < 1) || ($4 > 254)) cf_error("Max generation must be in range 1..254, got %u", $4);
+    PIPE_CFG->max_generation = $4;
+  }
  ;
 
 CF_CODE
diff --git a/proto/pipe/pipe.c b/proto/pipe/pipe.c
index 3caa85d0..7604cc79 100644
--- a/proto/pipe/pipe.c
+++ b/proto/pipe/pipe.c
@@ -56,15 +56,6 @@ pipe_rt_notify(struct proto *P, struct channel *src_ch, const net_addr *n, rte *
   if (!new && !old)
     return;
 
-  if (dst->table->pipe_busy)
-    {
-      log(L_ERR "Pipe loop detected when sending %N to table %s",
-	  n, dst->table->name);
-      return;
-    }
-
-  src_ch->table->pipe_busy = 1;
-
   if (new)
     {
       rta *a = alloca(rta_size(new->attrs));
@@ -76,23 +67,34 @@ pipe_rt_notify(struct proto *P, struct channel *src_ch, const net_addr *n, rte *
       rte e0 = {
 	.attrs = a,
 	.src = new->src,
+	.generation = new->generation + 1,
       };
 
       rte_update(dst, n, &e0, new->src);
     }
   else
     rte_update(dst, n, NULL, old->src);
-
-  src_ch->table->pipe_busy = 0;
 }
 
 static int
 pipe_preexport(struct channel *c, rte *e)
 {
-  struct proto *pp = e->sender->proto;
+  struct pipe_proto *p = (void *) c->proto;
+
+  /* Avoid direct loopbacks */
+  if (e->sender == c)
+    return -1;
 
-  if (pp == c->proto)
-    return -1;	/* Avoid local loops automatically */
+  /* Indirection check */
+  uint max_generation = ((struct pipe_config *) p->p.cf)->max_generation;
+  if (e->generation >= max_generation)
+  {
+    log_rl(&p->rl_gen, L_ERR "Route overpiped (%u hops of %u configured in %s) in table %s: %N %s/%u:%u",
+	e->generation, max_generation, c->proto->name,
+	c->table->name, e->net, e->src->proto->name, e->src->private_id, e->src->global_id);
+
+    return -1;
+  }
 
   return 0;
 }
@@ -177,6 +179,8 @@ pipe_init(struct proto_config *CF)
   P->preexport = pipe_preexport;
   P->reload_routes = pipe_reload_routes;
 
+  p->rl_gen = (struct tbf) TBF_DEFAULT_LOG_LIMITS;
+
   pipe_configure_channels(p, cf);
 
   return P;
diff --git a/proto/pipe/pipe.h b/proto/pipe/pipe.h
index 038c6666..60c857eb 100644
--- a/proto/pipe/pipe.h
+++ b/proto/pipe/pipe.h
@@ -12,12 +12,14 @@
 struct pipe_config {
   struct proto_config c;
   struct rtable_config *peer;		/* Table we're connected to */
+  u8 max_generation;
 };
 
 struct pipe_proto {
   struct proto p;
   struct channel *pri;
   struct channel *sec;
+  struct tbf rl_gen;
 };
 
 #endif