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authorOndrej Zajicek <santiago@crfreenet.org>2009-02-27 15:24:46 +0100
committerOndrej Zajicek <santiago@crfreenet.org>2009-02-27 15:24:46 +0100
commit82a79586e5810af2f0338cb4c5982e085b5c5292 (patch)
treec25310da25f371ed78028f406eeb55e2587e7077
parentcb5303927188de9504a6e18aedec299956a22b6f (diff)
downloadbird-82a79586e5810af2f0338cb4c5982e085b5c5292.tar
bird-82a79586e5810af2f0338cb4c5982e085b5c5292.zip
Better handling of too long attributes
This patch extends the length for attributes from 1024 to 2048 (because both AS_PATH and AS4_PATH attributes take 2+4 B per AS). If there is not enough space for attributes, Bird skips that route group. Old behavior (skipping remaining attributes) leads to skipping required attributes and session drop.
-rw-r--r--proto/bgp/attrs.c5
-rw-r--r--proto/bgp/packets.c47
2 files changed, 44 insertions, 8 deletions
diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c
index d8a6aad..91d4d06 100644
--- a/proto/bgp/attrs.c
+++ b/proto/bgp/attrs.c
@@ -347,7 +347,7 @@ bgp_get_attr_len(eattr *a)
* The bgp_encode_attrs() function takes a list of extended attributes
* and converts it to its BGP representation (a part of an Update message).
*
- * Result: Length of the attribute block generated.
+ * Result: Length of the attribute block generated or -1 if not enough space.
*/
unsigned int
bgp_encode_attrs(struct bgp_proto *p, byte *w, ea_list *attrs, int remains)
@@ -488,8 +488,7 @@ bgp_encode_attrs(struct bgp_proto *p, byte *w, ea_list *attrs, int remains)
return w - start;
err_no_buffer:
- log(L_ERR "BGP: attribute list too long, ignoring the remaining attributes");
- return w - start;
+ return -1;
}
static void
diff --git a/proto/bgp/packets.c b/proto/bgp/packets.c
index fe7472b..4256489 100644
--- a/proto/bgp/packets.c
+++ b/proto/bgp/packets.c
@@ -127,6 +127,18 @@ bgp_encode_prefixes(struct bgp_proto *p, byte *w, struct bgp_bucket *buck, unsig
return w - start;
}
+static void
+bgp_flush_prefixes(struct bgp_proto *p, struct bgp_bucket *buck)
+{
+ while (!EMPTY_LIST(buck->prefixes))
+ {
+ struct bgp_prefix *px = SKIP_BACK(struct bgp_prefix, bucket_node, HEAD(buck->prefixes));
+ log(L_ERR "%s: - route %I/%d skipped", p->p.name, px->n.prefix, px->n.pxlen);
+ rem_node(&px->bucket_node);
+ fib_delete(&p->prefix_fib, px);
+ }
+}
+
#ifndef IPV6 /* IPv4 version */
static byte *
@@ -150,7 +162,7 @@ bgp_create_update(struct bgp_conn *conn, byte *buf)
}
put_u16(buf, wd_size);
- if (remains >= 2048)
+ if (remains >= 3072)
{
while ((buck = (struct bgp_bucket *) HEAD(p->bucket_queue))->send_node.next)
{
@@ -161,8 +173,19 @@ bgp_create_update(struct bgp_conn *conn, byte *buf)
bgp_free_bucket(p, buck);
continue;
}
+
DBG("Processing bucket %p\n", buck);
- a_size = bgp_encode_attrs(p, w+2, buck->eattrs, 1024);
+ a_size = bgp_encode_attrs(p, w+2, buck->eattrs, 2048);
+
+ if (a_size < 0)
+ {
+ log(L_ERR "%s: Attribute list too long, skipping corresponding route group", p->p.name);
+ bgp_flush_prefixes(p, buck);
+ rem_node(&buck->send_node);
+ bgp_free_bucket(p, buck);
+ continue;
+ }
+
put_u16(w, a_size);
w += a_size + 2;
r_size = bgp_encode_prefixes(p, w, buck, remains - a_size);
@@ -211,11 +234,12 @@ bgp_create_update(struct bgp_conn *conn, byte *buf)
*tmp++ = 1;
ea->attrs[0].u.ptr->length = bgp_encode_prefixes(p, tmp, buck, remains-11);
size = bgp_encode_attrs(p, w, ea, remains);
+ ASSERT(size >= 0);
w += size;
remains -= size;
}
- if (remains >= 2048)
+ if (remains >= 3072)
{
while ((buck = (struct bgp_bucket *) HEAD(p->bucket_queue))->send_node.next)
{
@@ -226,8 +250,19 @@ bgp_create_update(struct bgp_conn *conn, byte *buf)
bgp_free_bucket(p, buck);
continue;
}
+
DBG("Processing bucket %p\n", buck);
- size = bgp_encode_attrs(p, w, buck->eattrs, 1024);
+ size = bgp_encode_attrs(p, w, buck->eattrs, 2048);
+
+ if (size < 0)
+ {
+ log(L_ERR "%s: Attribute list too long, ignoring corresponding route group", p->p.name);
+ bgp_flush_prefixes(p, buck);
+ rem_node(&buck->send_node);
+ bgp_free_bucket(p, buck);
+ continue;
+ }
+
w += size;
remains -= size;
tstart = tmp = bgp_attach_attr_wa(&ea, bgp_linpool, BA_MP_REACH_NLRI, remains-8);
@@ -274,7 +309,9 @@ bgp_create_update(struct bgp_conn *conn, byte *buf)
*tmp++ = 0; /* No SNPA information */
tmp += bgp_encode_prefixes(p, tmp, buck, remains - (8+3+32+1));
ea->attrs[0].u.ptr->length = tmp - tstart;
- w += bgp_encode_attrs(p, w, ea, remains);
+ size = bgp_encode_attrs(p, w, ea, remains);
+ ASSERT(size >= 0);
+ w += size;
break;
}
}