From 261816b0d4f3d4549a4402b95541b82fc7f10a4b Mon Sep 17 00:00:00 2001
From: "Ondrej Zajicek (work)" <santiago@crfreenet.org>
Date: Tue, 15 Nov 2016 16:24:39 +0100
Subject: [PATCH] BGP: Cluster list item should be prepended

Commit 3c09af41... changed behavior of int_set_add() from prepend to
append, which makes more sense for community list, but prepend must be
used for cluster list. Add int_set_prepend() and use it in cluster list
handling code.
---
 nest/a-set.c      | 23 +++++++++++++++++++++--
 nest/attrs.h      |  1 +
 proto/bgp/attrs.c |  2 +-
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/nest/a-set.c b/nest/a-set.c
index bd244e2e..a6c07f45 100644
--- a/nest/a-set.c
+++ b/nest/a-set.c
@@ -231,6 +231,26 @@ lc_set_contains(struct adata *list, lcomm val)
   return 0;
 }
 
+struct adata *
+int_set_prepend(struct linpool *pool, struct adata *list, u32 val)
+{
+  struct adata *res;
+  int len;
+
+  if (int_set_contains(list, val))
+    return list;
+
+  len = list ? list->length : 0;
+  res = lp_alloc(pool, sizeof(struct adata) + len + 4);
+  res->length = len + 4;
+
+  if (list)
+    memcpy(res->data + 4, list->data, list->length);
+
+  * (u32 *) res->data = val;
+
+  return res;
+}
 
 struct adata *
 int_set_add(struct linpool *pool, struct adata *list, u32 val)
@@ -248,8 +268,7 @@ int_set_add(struct linpool *pool, struct adata *list, u32 val)
   if (list)
     memcpy(res->data, list->data, list->length);
 
-  u32 *c = (u32 *) (res->data + len);
-  *c = val;
+  * (u32 *) (res->data + len) = val;
 
   return res;
 }
diff --git a/nest/attrs.h b/nest/attrs.h
index 548d71a9..a34e64d3 100644
--- a/nest/attrs.h
+++ b/nest/attrs.h
@@ -132,6 +132,7 @@ int lc_set_format(struct adata *set, int from, byte *buf, uint size);
 int int_set_contains(struct adata *list, u32 val);
 int ec_set_contains(struct adata *list, u64 val);
 int lc_set_contains(struct adata *list, lcomm val);
+struct adata *int_set_prepend(struct linpool *pool, struct adata *list, u32 val);
 struct adata *int_set_add(struct linpool *pool, struct adata *list, u32 val);
 struct adata *ec_set_add(struct linpool *pool, struct adata *list, u64 val);
 struct adata *lc_set_add(struct linpool *pool, struct adata *list, lcomm val);
diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c
index 0309c1f7..aa2a3b46 100644
--- a/proto/bgp/attrs.c
+++ b/proto/bgp/attrs.c
@@ -1077,7 +1077,7 @@ static inline void
 bgp_cluster_list_prepend(rte *e, ea_list **attrs, struct linpool *pool, u32 cid)
 {
   eattr *a = ea_find(e->attrs->eattrs, EA_CODE(EAP_BGP, BA_CLUSTER_LIST));
-  bgp_attach_attr(attrs, pool, BA_CLUSTER_LIST, (uintptr_t) int_set_add(pool, a ? a->u.ptr : NULL, cid));
+  bgp_attach_attr(attrs, pool, BA_CLUSTER_LIST, (uintptr_t) int_set_prepend(pool, a ? a->u.ptr : NULL, cid));
 }
 
 static int