Make bgpd 4-byte AS compatible. All internal representations of AS numbers

are now 4-byte instead of the old 2-byte numbers. The only exception are
communities because they can not be switched. The RDE will inflate and deflate
the ASPATH and AGGREGATOR attributes on demand and create the NEW_ASPATH and
NEW_AGGREGATOR field whenever needed. Both old and new stile sessions are
supported and can be mixed. Currently new stile sessions with the 4-byte AS
number capability turned on are only enabled if one of the AS numbers involved
is a 4-byte one.
This is based on an initial diff by Geoff Huston gih (at) apnic (dot) net
Cleanup, testing and bug-fixes by myself (via AS 3.10).
Currently mrt table dumps are producing incompatible output this will be fixed
afterwards -- this diff is already big enough.

"get it in if you think it is ready" henning@

1 files changed, 53 insertions, 18 deletions

diff --git a/usr.sbin/bgpd/session.c b/usr.sbin/bgpd/session.c
index 9f8e7718d22..1f00f61a599 100644
--- a/usr.sbin/bgpd/session.c
+++ b/usr.sbin/bgpd/session.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: session.c,v 1.272 2007/03/28 11:53:48 claudio Exp $ */
+/*	$OpenBSD: session.c,v 1.273 2007/04/23 13:04:24 claudio Exp $ */
 
 /*
  * Copyright (c) 2003, 2004, 2005 Henning Brauer <henning@openbsd.org>
@@ -32,6 +32,7 @@
 #include <err.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <limits.h>
 #include <poll.h>
 #include <pwd.h>
 #include <signal.h>
@@ -82,7 +83,7 @@ int	parse_open(struct peer *);
 int	parse_update(struct peer *);
 int	parse_refresh(struct peer *);
 int	parse_notification(struct peer *);
-int	parse_capabilities(struct peer *, u_char *, u_int16_t);
+int	parse_capabilities(struct peer *, u_char *, u_int16_t, u_int32_t *);
 void	session_dispatch_imsg(struct imsgbuf *, int, u_int *);
 void	session_up(struct peer *);
 void	session_down(struct peer *);
@@ -1247,6 +1248,7 @@ session_capa_ann_none(struct peer *peer)
 	peer->capa.ann.mp_v4 = SAFI_NONE;
 	peer->capa.ann.refresh = 0;
 	peer->capa.ann.restart = 0;
+	peer->capa.ann.as4byte = 0;
 }
 
 int
@@ -1380,6 +1382,15 @@ session_open(struct peer *p)
 		errs += buf_add(opb, &c, 4);
 	}
 
+	/* 4-bytes AS numbers, draft-ietf-idr-as4bytes-12 */
+	if (p->capa.ann.as4byte) {	/* 4 bytes data */
+		u_int32_t	nas;
+
+		nas = htonl(conf->as);
+		errs += session_capa_add(p, opb, CAPA_AS4BYTE, 4, &optparamlen);
+		errs += buf_add(opb, &nas, 4);
+	}
+
 	len = MSGSIZE_OPEN_MIN + optparamlen;
 	if (errs || (buf = session_newmsg(OPEN, len)) == NULL) {
 		buf_free(opb);
@@ -1388,7 +1399,10 @@ session_open(struct peer *p)
 	}
 
 	msg.version = 4;
-	msg.myas = htons(conf->as);
+	if (conf->as > USHRT_MAX)
+		msg.myas = htons(conf->short_as);
+	else
+		msg.myas = htons(conf->as);
 	if (p->conf.holdtime)
 		msg.holdtime = htons(p->conf.holdtime);
 	else
@@ -1816,9 +1830,9 @@ parse_open(struct peer *peer)
 {
 	u_char		*p, *op_val;
 	u_int8_t	 version, rversion;
-	u_int16_t	 as, msglen;
+	u_int16_t	 short_as, msglen;
 	u_int16_t	 holdtime, oholdtime, myholdtime;
-	u_int32_t	 bgpid;
+	u_int32_t	 as, bgpid;
 	u_int8_t	 optparamlen, plen;
 	u_int8_t	 op_type, op_len;
 
@@ -1846,22 +1860,16 @@ parse_open(struct peer *peer)
 		return (-1);
 	}
 
-	memcpy(&as, p, sizeof(as));
-	p += sizeof(as);
+	memcpy(&short_as, p, sizeof(short_as));
+	p += sizeof(short_as);
+	as = peer->short_as = ntohs(short_as);
 
 	/* if remote-as is zero and it's a cloned neighbor, accept any */
-	if (peer->conf.cloned && !peer->conf.remote_as) {
-		peer->conf.remote_as = ntohs(as);
+	if (peer->conf.cloned && !peer->conf.remote_as && as != AS_TRANS) {
+		peer->conf.remote_as = as;
 		peer->conf.ebgp = (peer->conf.remote_as != conf->as);
 	}
 
-	if (peer->conf.remote_as != ntohs(as)) {
-		log_peer_warnx(&peer->conf, "peer sent wrong AS %u", ntohs(as));
-		session_notification(peer, ERR_OPEN, ERR_OPEN_AS, NULL, 0);
-		change_state(peer, STATE_IDLE, EVNT_RCVD_OPEN);
-		return (-1);
-	}
-
 	memcpy(&oholdtime, p, sizeof(oholdtime));
 	p += sizeof(oholdtime);
 
@@ -1940,7 +1948,8 @@ parse_open(struct peer *peer)
 
 		switch (op_type) {
 		case OPT_PARAM_CAPABILITIES:		/* RFC 3392 */
-			if (parse_capabilities(peer, op_val, op_len) == -1) {
+			if (parse_capabilities(peer, op_val, op_len,
+			    &as) == -1) {
 				session_notification(peer, ERR_OPEN, 0,
 				    NULL, 0);
 				change_state(peer, STATE_IDLE, EVNT_RCVD_OPEN);
@@ -1968,6 +1977,14 @@ parse_open(struct peer *peer)
 		}
 	}
 
+	if (peer->conf.remote_as != as) {
+		log_peer_warnx(&peer->conf, "peer sent wrong AS %s",
+		    log_as(as));
+		session_notification(peer, ERR_OPEN, ERR_OPEN_AS, NULL, 0);
+		change_state(peer, STATE_IDLE, EVNT_RCVD_OPEN);
+		return (-1);
+	}
+
 	return (0);
 }
 
@@ -2103,6 +2120,11 @@ parse_notification(struct peer *peer)
 				log_peer_warnx(&peer->conf,
 				    "disabling restart capability");
 				break;
+			case CAPA_AS4BYTE:
+				peer->capa.ann.as4byte = 0;
+				log_peer_warnx(&peer->conf,
+				    "disabling 4-byte AS num capability");
+				break;
 			default:	/* should not happen... */
 				log_peer_warnx(&peer->conf, "received "
 				    "\"unsupported capability\" notification "
@@ -2126,7 +2148,7 @@ parse_notification(struct peer *peer)
 }
 
 int
-parse_capabilities(struct peer *peer, u_char *d, u_int16_t dlen)
+parse_capabilities(struct peer *peer, u_char *d, u_int16_t dlen, u_int32_t *as)
 {
 	u_int16_t	 len;
 	u_int8_t	 capa_code;
@@ -2134,6 +2156,7 @@ parse_capabilities(struct peer *peer, u_char *d, u_int16_t dlen)
 	u_char		*capa_val;
 	u_int16_t	 mp_afi;
 	u_int8_t	 mp_safi;
+	u_int32_t	 remote_as;
 
 	len = dlen;
 	while (len > 0) {
@@ -2203,6 +2226,17 @@ parse_capabilities(struct peer *peer, u_char *d, u_int16_t dlen)
 			peer->capa.peer.restart = 1;
 			/* we don't care about the further restart capas yet */
 			break;
+		case CAPA_AS4BYTE:
+			if (capa_len != 4) {
+				log_peer_warnx(&peer->conf,
+				    "parse_capabilities: "
+				    "expect len 4, len is %u", capa_len);
+				return (-1);
+			}
+			memcpy(&remote_as, capa_val, sizeof(remote_as));
+			*as = ntohl(remote_as);
+			peer->capa.peer.as4byte = 1;
+			break;
 		default:
 			break;
 		}
@@ -2754,6 +2788,7 @@ session_up(struct peer *p)
 	}
 
 	sup.remote_bgpid = p->remote_bgpid;
+	sup.short_as = p->short_as;
 	memcpy(&sup.capa_announced, &p->capa.ann, sizeof(sup.capa_announced));
 	memcpy(&sup.capa_received, &p->capa.peer, sizeof(sup.capa_received));
 	p->stats.last_updown = time(NULL);