Implement "enforce neighbor-as yes|no" which is by default on for ebgp

neighbors. While doing that check also that the nexthop is valid (not class D
or E and not in 127/8 range). Kill some TODO and XXX and rename the british
neighbour to neighbor as used everywhere else. OK henning@

7 files changed, 52 insertions, 22 deletions

diff --git a/usr.sbin/bgpd/bgpd.h b/usr.sbin/bgpd/bgpd.h
index 801c649948b..0339b077619 100644
--- a/usr.sbin/bgpd/bgpd.h
+++ b/usr.sbin/bgpd/bgpd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bgpd.h,v 1.99 2004/02/26 09:53:58 claudio Exp $ */
+/*	$OpenBSD: bgpd.h,v 1.100 2004/02/26 14:00:33 claudio Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -125,6 +125,12 @@ enum announce_type {
 	ANNOUNCE_ALL
 };
 
+enum enforce_as {
+	ENFORCE_AS_UNDEF,
+	ENFORCE_AS_OFF,
+	ENFORCE_AS_ON
+};
+
 struct filter_set {
 	u_int8_t	flags;
 	u_int32_t	localpref;
@@ -150,6 +156,7 @@ struct peer_config {
 	u_int16_t		 min_holdtime;
 	struct filter_set	 attrset;
 	enum announce_type	 announce_type;
+	enum enforce_as		 enforce_as;
 	char			 tcp_md5_key[TCP_MD5_KEY_LEN];
 	enum reconf_action	 reconf_action;
 };
diff --git a/usr.sbin/bgpd/config.c b/usr.sbin/bgpd/config.c
index b96706ba913..45120a2cbd5 100644
--- a/usr.sbin/bgpd/config.c
+++ b/usr.sbin/bgpd/config.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: config.c,v 1.28 2004/02/10 23:10:23 henning Exp $ */
+/*	$OpenBSD: config.c,v 1.29 2004/02/26 14:00:33 claudio Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -59,6 +59,9 @@ merge_config(struct bgpd_config *xconf, struct bgpd_config *conf,
 		if (p->conf.announce_type == ANNOUNCE_UNDEF)
 			p->conf.announce_type = p->conf.ebgp == 0 ?
 			    ANNOUNCE_ALL : ANNOUNCE_SELF;
+		if (p->conf.enforce_as == ENFORCE_AS_UNDEF)
+			p->conf.enforce_as = p->conf.ebgp == 0 ?
+			    ENFORCE_AS_OFF : ENFORCE_AS_ON;
 	}
 
 	memcpy(xconf, conf, sizeof(struct bgpd_config));
diff --git a/usr.sbin/bgpd/parse.y b/usr.sbin/bgpd/parse.y
index e77a5193242..b7119fa6d2d 100644
--- a/usr.sbin/bgpd/parse.y
+++ b/usr.sbin/bgpd/parse.y
@@ -1,4 +1,4 @@
-/*	$OpenBSD: parse.y,v 1.62 2004/02/26 13:54:50 claudio Exp $ */
+/*	$OpenBSD: parse.y,v 1.63 2004/02/26 14:00:33 claudio Exp $ */
 
 /*
  * Copyright (c) 2002, 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -100,6 +100,7 @@ typedef struct {
 %token	AS ROUTERID HOLDTIME YMIN LISTEN ON FIBUPDATE
 %token	GROUP NEIGHBOR NETWORK
 %token	REMOTEAS DESCR LOCALADDR MULTIHOP PASSIVE MAXPREFIX ANNOUNCE
+%token	ENFORCE NEIGHBORAS
 %token	DUMP TABLE IN OUT
 %token	LOG
 %token	TCP MD5SIG PASSWORD KEY
@@ -393,6 +394,12 @@ peeropts	: REMOTEAS number	{
 				YYERROR;
 			}
 		}
+		| ENFORCE NEIGHBORAS yesno {
+			if ($3)
+				curpeer->conf.enforce_as = ENFORCE_AS_ON;
+			else
+				curpeer->conf.enforce_as = ENFORCE_AS_OFF;
+		}
 		| MAXPREFIX number {
 			curpeer->conf.max_prefix = $2;
 		}
@@ -681,6 +688,7 @@ lookup(char *s)
 		{ "deny",		DENY},
 		{ "descr",		DESCR},
 		{ "dump",		DUMP},
+		{ "enforce",		ENFORCE},
 		{ "fib-update",		FIBUPDATE},
 		{ "from",		FROM},
 		{ "group",		GROUP},
@@ -697,6 +705,7 @@ lookup(char *s)
 		{ "med",		MED},
 		{ "min",		YMIN},
 		{ "multihop",		MULTIHOP},
+		{ "neighbor-as",	NEIGHBORAS},
 		{ "neighbor",		NEIGHBOR},
 		{ "network",		NETWORK},
 		{ "nexthop",		NEXTHOP},
diff --git a/usr.sbin/bgpd/rde.c b/usr.sbin/bgpd/rde.c
index 83b93321053..38444f5a210 100644
--- a/usr.sbin/bgpd/rde.c
+++ b/usr.sbin/bgpd/rde.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rde.c,v 1.87 2004/02/26 09:53:58 claudio Exp $ */
+/*	$OpenBSD: rde.c,v 1.88 2004/02/26 14:00:33 claudio Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -409,8 +409,8 @@ rde_update_dispatch(struct imsg *imsg)
 	/* parse path attributes */
 	attr_init(&attrs);
 	while (attrpath_len > 0) {
-		if ((pos = attr_parse(p, attrpath_len, &attrs,
-		    peer->conf.ebgp)) < 0) {
+		if ((pos = attr_parse(p, attrpath_len, &attrs, peer->conf.ebgp,
+		    peer->conf.enforce_as, peer->conf.remote_as)) < 0) {
 			emsg = attr_error(p, attrpath_len, &attrs,
 			    &subtype, &size);
 			rde_update_err(peer, ERR_UPDATE, subtype, emsg, size);
diff --git a/usr.sbin/bgpd/rde.h b/usr.sbin/bgpd/rde.h
index eb12f60dae2..4b173ce7b6a 100644
--- a/usr.sbin/bgpd/rde.h
+++ b/usr.sbin/bgpd/rde.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rde.h,v 1.29 2004/02/19 23:07:00 claudio Exp $ */
+/*	$OpenBSD: rde.h,v 1.30 2004/02/26 14:00:33 claudio Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Claudio Jeker <claudio@openbsd.org> and
@@ -213,7 +213,8 @@ u_int16_t	 rde_local_as(void);
 
 /* rde_attr.c */
 void		 attr_init(struct attr_flags *);
-int		 attr_parse(u_char *, u_int16_t, struct attr_flags *, int);
+int		 attr_parse(u_char *, u_int16_t, struct attr_flags *, int,
+		     enum enforce_as, u_int16_t);
 u_char		*attr_error(u_char *, u_int16_t, struct attr_flags *,
 		     u_int8_t *, u_int16_t *);
 u_int8_t	 attr_missing(struct attr_flags *, int);
@@ -237,7 +238,7 @@ int		 aspath_write(void *, u_int16_t, struct aspath *, u_int16_t,
 u_char		*aspath_dump(struct aspath *);
 u_int16_t	 aspath_length(struct aspath *);
 u_int16_t	 aspath_count(struct aspath *);
-u_int16_t	 aspath_neighbour(struct aspath *);
+u_int16_t	 aspath_neighbor(struct aspath *);
 u_int32_t	 aspath_hash(struct aspath *);
 int		 aspath_loopfree(struct aspath *, u_int16_t);
 int		 aspath_compare(struct aspath *, struct aspath *);
diff --git a/usr.sbin/bgpd/rde_attr.c b/usr.sbin/bgpd/rde_attr.c
index 9cb130fa201..cc6bc77f53d 100644
--- a/usr.sbin/bgpd/rde_attr.c
+++ b/usr.sbin/bgpd/rde_attr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rde_attr.c,v 1.14 2004/02/24 15:44:33 claudio Exp $ */
+/*	$OpenBSD: rde_attr.c,v 1.15 2004/02/26 14:00:33 claudio Exp $ */
 
 /*
  * Copyright (c) 2004 Claudio Jeker <claudio@openbsd.org>
@@ -19,6 +19,8 @@
 #include <sys/types.h>
 #include <sys/queue.h>
 
+#include <netinet/in.h>
+
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
@@ -59,7 +61,8 @@ attr_init(struct attr_flags *a)
 }
 
 int
-attr_parse(u_char *p, u_int16_t len, struct attr_flags *a, int ebgp)
+attr_parse(u_char *p, u_int16_t len, struct attr_flags *a, int ebgp,
+    enum enforce_as enforce_as, u_int16_t remote_as)
 {
 	u_int32_t	 tmp32;
 	u_int16_t	 attr_len;
@@ -108,7 +111,10 @@ attr_parse(u_char *p, u_int16_t len, struct attr_flags *a, int ebgp)
 			return (-1);
 		WFLAG(a->wflags, F_ATTR_ASPATH);
 		a->aspath = aspath_create(p, attr_len);
-		/* XXX enforce remote-as == left most AS if not disabled */
+		if (enforce_as == ENFORCE_AS_ON &&
+		    remote_as != aspath_neighbor(a->aspath))
+			return (-1);
+
 		plen += attr_len;
 		break;
 	case ATTR_NEXTHOP:
@@ -118,7 +124,14 @@ attr_parse(u_char *p, u_int16_t len, struct attr_flags *a, int ebgp)
 			return (-1);
 		WFLAG(a->wflags, F_ATTR_NEXTHOP);
 		UPD_READ(&a->nexthop, p, plen, 4);	/* network byte order */
-		/* XXX check if the nexthop is a valid IP address */
+		/*
+		 * Check if the nexthop is a valid IP address. We consider
+		 * multicast, experimental and loopback addresses as invalid.
+		 */
+		tmp32 = ntohl(a->nexthop);
+		if (IN_MULTICAST(tmp32) || IN_BADCLASS(tmp32) ||
+		    (tmp32 & 0x7f000000) == 0x7f000000) 
+			return (-1);
 		break;
 	case ATTR_MED:
 		if (attr_len != 4)
@@ -480,10 +493,6 @@ attr_optfree(struct attr_flags *attr)
 
 /* aspath specific functions */
 
-/* TODO
- * aspath regexp search,
- * aspath to string converter
- */
 static u_int16_t	aspath_extract(void *, int);
 
 /*
@@ -642,6 +651,7 @@ void
 aspath_destroy(struct aspath *aspath)
 {
 	/* only the aspath needs to be freed */
+	if (aspath == NULL) return;
 	free(aspath);
 }
 
@@ -681,11 +691,11 @@ aspath_count(struct aspath *aspath)
 }
 
 u_int16_t
-aspath_neighbour(struct aspath *aspath)
+aspath_neighbor(struct aspath *aspath)
 {
 	/*
 	 * Empty aspath is OK -- internal as route.
-	 * But what is the neighbour? For now let's return 0 that
+	 * But what is the neighbor? For now let's return 0 that
 	 * should not break anything.
 	 */
 
diff --git a/usr.sbin/bgpd/rde_decide.c b/usr.sbin/bgpd/rde_decide.c
index b16e2a05757..9580e9fbf42 100644
--- a/usr.sbin/bgpd/rde_decide.c
+++ b/usr.sbin/bgpd/rde_decide.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rde_decide.c,v 1.28 2004/02/17 14:22:40 claudio Exp $ */
+/*	$OpenBSD: rde_decide.c,v 1.29 2004/02/26 14:00:33 claudio Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Claudio Jeker <claudio@openbsd.org>
@@ -147,8 +147,8 @@ prefix_cmp(struct prefix *p1, struct prefix *p2)
 		return (asp2->flags.origin - asp1->flags.origin);
 
 	/* 5. MED decision, only comparable between the same neighboring AS */
-	if (aspath_neighbour(asp1->flags.aspath) ==
-	    aspath_neighbour(asp2->flags.aspath))
+	if (aspath_neighbor(asp1->flags.aspath) ==
+	    aspath_neighbor(asp2->flags.aspath))
 		/* the bigger, the better */
 		if ((asp1->flags.med - asp2->flags.med) != 0)
 			return (asp1->flags.med - asp2->flags.med);