diff options
Diffstat (limited to 'proto/bgp/attrs.c')
| -rw-r--r-- | proto/bgp/attrs.c | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c index 9b243763..39297dd7 100644 --- a/proto/bgp/attrs.c +++ b/proto/bgp/attrs.c @@ -404,6 +404,15 @@ bgp_format_origin(eattr *a, byte *buf, uint size UNUSED) } +static inline int +bgp_as_path_first_as_equal(const byte *data, uint len, u32 asn) +{ + return (len >= 6) && + ((data[0] == AS_PATH_SEQUENCE) || (data[0] == AS_PATH_CONFED_SEQUENCE)) && + (data[1] > 0) && + (get_u32(data+2) == asn); +} + static int bgp_encode_as_path(struct bgp_write_state *s, eattr *a, byte *buf, uint size) { @@ -433,11 +442,6 @@ bgp_decode_as_path(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte if (!as_path_valid(data, len, as_length, as_sets, as_confed, err, sizeof(err))) WITHDRAW("Malformed AS_PATH attribute - %s", err); - /* In some circumstances check for initial AS_CONFED_SEQUENCE; RFC 5065 5.0 */ - if (p->is_interior && !p->is_internal && - ((len < 2) || (data[0] != AS_PATH_CONFED_SEQUENCE))) - WITHDRAW("Malformed AS_PATH attribute - %s", "missing initial AS_CONFED_SEQUENCE"); - if (!s->as4_session) { /* Prepare 32-bit AS_PATH (from 16-bit one) in a temporary buffer */ @@ -446,6 +450,16 @@ bgp_decode_as_path(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte len = as_path_16to32(data, src, len); } + /* In some circumstances check for initial AS_CONFED_SEQUENCE; RFC 5065 5.0 */ + if (p->is_interior && !p->is_internal && + ((len < 2) || (data[0] != AS_PATH_CONFED_SEQUENCE))) + WITHDRAW("Malformed AS_PATH attribute - %s", "missing initial AS_CONFED_SEQUENCE"); + + /* Reject routes with first AS in AS_PATH not matching neighbor AS; RFC 4271 6.3 */ + if (!p->is_internal && p->cf->enforce_first_as && + !bgp_as_path_first_as_equal(data, len, p->remote_as)) + WITHDRAW("Malformed AS_PATH attribute - %s", "First AS differs from neigbor AS"); + bgp_set_attr_data(to, s->pool, BA_AS_PATH, flags, data, len); } |