From: Pavel Tvrdík <pawel.tvrdik@gmail.com>
Date: Tue, 5 Jan 2016 17:05:06 +0000 (+0100)
Subject: MRT Table Dump: Fix size of AS_PATH in BGP Attributes
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5125741512eedd347dc05e705a8d663267fa137e;p=thirdparty%2Fbird.git

MRT Table Dump: Fix size of AS_PATH in BGP Attributes

All AS numbers in the AS_PATH attribute in RIB Entries MUST be encoded as 4-byte AS numbers.
 -- RFC 6396

Thanks to Colin Petrie for noticing us about this bug in BIRD!
---

diff --git a/proto/bgp/mrt.c b/proto/bgp/mrt.c
index d4f8a434f..713be83a6 100644
--- a/proto/bgp/mrt.c
+++ b/proto/bgp/mrt.c
@@ -101,7 +101,11 @@ bgp_mrt_table_dump_step(struct mrt_table_dump_ctx *state)
 	  continue;
 	}
 
-	attributes_length = bgp_encode_attrs(p, attributes_buffer, e->attrs->eattrs, BGP_ATTR_BUFFER_SIZE);
+	struct bgp_proto tmp_bgp_proto = {
+	    .as4_session = 1, /* to force build AS_PATH as 32bit AS in bgp_encode_attrs() */
+	};
+
+	attributes_length = bgp_encode_attrs(&tmp_bgp_proto, attributes_buffer, e->attrs->eattrs, BGP_ATTR_BUFFER_SIZE);
 	if (attributes_length == -1)
 	{
 	  log(L_WARN "%s: MRT Table Dump for %I/%u: Attribute list too long, let it blank", p->p.name, n->n.prefix, n->n.pxlen);