Implement reception of multiple paths per BGP session. This is one

side of RFC7911 and the send portion will follow.

The path-id is extracted from the NLRI encoding an put into struct
prefix.  To do this the prefix_by_peer() function gets a path-id
argument.  If a session is not path-id enabled this argument will
be always 0. If a session is path-id enabled the value is taken
from the NLRI and can be anything, including 0. The value has no
meaning in itself. Still to make sure the decision process is able
to break a tie the path-id is checked as the last step (this is not
part of the RFC but required).

OK benno@

1 files changed, 133 insertions, 46 deletions

diff --git a/usr.sbin/bgpd/rde.c b/usr.sbin/bgpd/rde.c
index 24dc6716f65..65696e253e2 100644
--- a/usr.sbin/bgpd/rde.c
+++ b/usr.sbin/bgpd/rde.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rde.c,v 1.531 2021/07/27 07:50:01 claudio Exp $ */
+/*	$OpenBSD: rde.c,v 1.532 2021/08/09 08:15:34 claudio Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -50,10 +50,10 @@ void		 rde_dispatch_imsg_parent(struct imsgbuf *);
 void		 rde_dispatch_imsg_rtr(struct imsgbuf *);
 void		 rde_dispatch_imsg_peer(struct rde_peer *, void *);
 void		 rde_update_dispatch(struct rde_peer *, struct imsg *);
-int		 rde_update_update(struct rde_peer *, struct filterstate *,
+int		 rde_update_update(struct rde_peer *, u_int32_t,
+                     struct filterstate *, struct bgpd_addr *, u_int8_t);
+void		 rde_update_withdraw(struct rde_peer *, u_int32_t,
 		     struct bgpd_addr *, u_int8_t);
-void		 rde_update_withdraw(struct rde_peer *, struct bgpd_addr *,
-		     u_int8_t);
 int		 rde_attr_parse(u_char *, u_int16_t, struct rde_peer *,
 		     struct filterstate *, struct mpattr *);
 int		 rde_attr_add(struct filterstate *, u_char *, u_int16_t);
@@ -1183,7 +1183,7 @@ rde_update_dispatch(struct rde_peer *peer, struct imsg *imsg)
 	u_int16_t		 attrpath_len;
 	u_int16_t		 nlri_len;
 	u_int8_t		 aid, prefixlen, safi, subtype;
-	u_int32_t		 fas;
+	u_int32_t		 fas, pathid;
 
 	p = imsg->data;
 
@@ -1288,6 +1288,21 @@ rde_update_dispatch(struct rde_peer *peer, struct imsg *imsg)
 			goto done;
 		}
 
+		if (peer_has_add_path(peer, AID_INET, CAPA_AP_RECV)) {
+			if (len <= sizeof(pathid)) {
+				log_peer_warnx(&peer->conf,
+				    "bad withdraw prefix");
+				rde_update_err(peer, ERR_UPDATE,
+				    ERR_UPD_NETWORK, NULL, 0);
+				goto done;
+			}
+			memcpy(&pathid, p, sizeof(pathid));
+			pathid = ntohl(pathid);
+			p += sizeof(pathid);
+			len -= sizeof(pathid);
+		} else
+			pathid = 0;
+
 		if ((pos = nlri_get_prefix(p, len, &prefix,
 		    &prefixlen)) == -1) {
 			/*
@@ -1302,7 +1317,7 @@ rde_update_dispatch(struct rde_peer *peer, struct imsg *imsg)
 		p += pos;
 		len -= pos;
 
-		rde_update_withdraw(peer, &prefix, prefixlen);
+		rde_update_withdraw(peer, pathid, &prefix, prefixlen);
 	}
 
 	/* withdraw MP_UNREACH_NLRI if available */
@@ -1339,6 +1354,23 @@ rde_update_dispatch(struct rde_peer *peer, struct imsg *imsg)
 		}
 
 		while (mplen > 0) {
+			if (peer_has_add_path(peer, aid, CAPA_AP_RECV)) {
+				if (mplen <= sizeof(pathid)) {
+					log_peer_warnx(&peer->conf,
+					    "bad %s withdraw prefix",
+					    aid2str(aid));
+					rde_update_err(peer, ERR_UPDATE,
+					    ERR_UPD_OPTATTR,
+					    mpa.unreach, mpa.unreach_len);
+					goto done;
+				}
+				memcpy(&pathid, mpp, sizeof(pathid));
+				pathid = ntohl(pathid);
+				mpp += sizeof(pathid);
+				mplen -= sizeof(pathid);
+			} else
+				pathid = 0;
+
 			switch (aid) {
 			case AID_INET6:
 				if ((pos = nlri_get_prefix6(mpp, mplen,
@@ -1381,7 +1413,7 @@ rde_update_dispatch(struct rde_peer *peer, struct imsg *imsg)
 			mpp += pos;
 			mplen -= pos;
 
-			rde_update_withdraw(peer, &prefix, prefixlen);
+			rde_update_withdraw(peer, pathid, &prefix, prefixlen);
 		}
 
 		if ((state.aspath.flags & ~F_ATTR_MP_UNREACH) == 0)
@@ -1401,6 +1433,21 @@ rde_update_dispatch(struct rde_peer *peer, struct imsg *imsg)
 			goto done;
 		}
 
+		if (peer_has_add_path(peer, AID_INET, CAPA_AP_RECV)) {
+			if (nlri_len <= sizeof(pathid)) {
+				log_peer_warnx(&peer->conf,
+				    "bad nlri prefix");
+				rde_update_err(peer, ERR_UPDATE,
+				    ERR_UPD_NETWORK, NULL, 0);
+				goto done;
+			}
+			memcpy(&pathid, p, sizeof(pathid));
+			pathid = ntohl(pathid);
+			p += sizeof(pathid);
+			nlri_len -= sizeof(pathid);
+		} else
+			pathid = 0;
+
 		if ((pos = nlri_get_prefix(p, nlri_len, &prefix,
 		    &prefixlen)) == -1) {
 			log_peer_warnx(&peer->conf, "bad nlri prefix");
@@ -1411,7 +1458,8 @@ rde_update_dispatch(struct rde_peer *peer, struct imsg *imsg)
 		p += pos;
 		nlri_len -= pos;
 
-		if (rde_update_update(peer, &state, &prefix, prefixlen) == -1)
+		if (rde_update_update(peer, pathid, &state,
+		    &prefix, prefixlen) == -1)
 			goto done;
 
 	}
@@ -1456,6 +1504,22 @@ rde_update_dispatch(struct rde_peer *peer, struct imsg *imsg)
 		mplen -= pos;
 
 		while (mplen > 0) {
+			if (peer_has_add_path(peer, aid, CAPA_AP_RECV)) {
+				if (mplen <= sizeof(pathid)) {
+					log_peer_warnx(&peer->conf,
+					    "bad %s nlri prefix", aid2str(aid));
+					rde_update_err(peer, ERR_UPDATE,
+					    ERR_UPD_OPTATTR,
+					    mpa.reach, mpa.reach_len);
+					goto done;
+				}
+				memcpy(&pathid, mpp, sizeof(pathid));
+				pathid = ntohl(pathid);
+				mpp += sizeof(pathid);
+				mplen -= sizeof(pathid);
+			} else
+				pathid = 0;
+
 			switch (aid) {
 			case AID_INET6:
 				if ((pos = nlri_get_prefix6(mpp, mplen,
@@ -1498,7 +1562,7 @@ rde_update_dispatch(struct rde_peer *peer, struct imsg *imsg)
 			mpp += pos;
 			mplen -= pos;
 
-			if (rde_update_update(peer, &state,
+			if (rde_update_update(peer, pathid, &state,
 			    &prefix, prefixlen) == -1)
 				goto done;
 		}
@@ -1509,8 +1573,8 @@ done:
 }
 
 int
-rde_update_update(struct rde_peer *peer, struct filterstate *in,
-    struct bgpd_addr *prefix, u_int8_t prefixlen)
+rde_update_update(struct rde_peer *peer, u_int32_t path_id,
+    struct filterstate *in, struct bgpd_addr *prefix, u_int8_t prefixlen)
 {
 	struct filterstate	 state;
 	enum filter_actions	 action;
@@ -1523,8 +1587,8 @@ rde_update_update(struct rde_peer *peer, struct filterstate *in,
 	    aspath_origin(in->aspath.aspath));
 
 	/* add original path to the Adj-RIB-In */
-	if (prefix_update(rib_byid(RIB_ADJ_IN), peer, in, prefix, prefixlen,
-	    vstate) == 1)
+	if (prefix_update(rib_byid(RIB_ADJ_IN), peer, path_id, in,
+	    prefix, prefixlen, vstate) == 1)
 		peer->prefix_cnt++;
 
 	/* max prefix checker */
@@ -1552,9 +1616,9 @@ rde_update_update(struct rde_peer *peer, struct filterstate *in,
 			rde_update_log("update", i, peer,
 			    &state.nexthop->exit_nexthop, prefix,
 			    prefixlen);
-			prefix_update(rib, peer, &state, prefix,
+			prefix_update(rib, peer, path_id, &state, prefix,
 			    prefixlen, vstate);
-		} else if (prefix_withdraw(rib, peer, prefix,
+		} else if (prefix_withdraw(rib, peer, path_id, prefix,
 		    prefixlen)) {
 			rde_update_log(wmsg, i, peer,
 			    NULL, prefix, prefixlen);
@@ -1567,8 +1631,8 @@ rde_update_update(struct rde_peer *peer, struct filterstate *in,
 }
 
 void
-rde_update_withdraw(struct rde_peer *peer, struct bgpd_addr *prefix,
-    u_int8_t prefixlen)
+rde_update_withdraw(struct rde_peer *peer, u_int32_t path_id,
+    struct bgpd_addr *prefix, u_int8_t prefixlen)
 {
 	u_int16_t i;
 
@@ -1576,13 +1640,14 @@ rde_update_withdraw(struct rde_peer *peer, struct bgpd_addr *prefix,
 		struct rib *rib = rib_byid(i);
 		if (rib == NULL)
 			continue;
-		if (prefix_withdraw(rib, peer, prefix, prefixlen))
+		if (prefix_withdraw(rib, peer, path_id, prefix, prefixlen))
 			rde_update_log("withdraw", i, peer, NULL, prefix,
 			    prefixlen);
 	}
 
 	/* remove original path form the Adj-RIB-In */
-	if (prefix_withdraw(rib_byid(RIB_ADJ_IN), peer, prefix, prefixlen))
+	if (prefix_withdraw(rib_byid(RIB_ADJ_IN), peer, path_id,
+	    prefix, prefixlen))
 		peer->prefix_cnt--;
 
 	peer->prefix_rcvd_withdraw++;
@@ -2292,28 +2357,31 @@ rde_reflector(struct rde_peer *peer, struct rde_aspath *asp)
  * control specific functions
  */
 static void
-rde_dump_rib_as(struct prefix *p, struct rde_aspath *asp, pid_t pid, int flags)
+rde_dump_rib_as(struct prefix *p, struct rde_aspath *asp, pid_t pid, int flags,
+    int adjout)
 {
 	struct ctl_show_rib	 rib;
 	struct ibuf		*wbuf;
 	struct attr		*a;
 	struct nexthop		*nexthop;
 	struct rib_entry	*re;
+	struct rde_peer		*peer;
 	void			*bp;
 	time_t			 staletime;
 	size_t			 aslen;
 	u_int8_t		 l;
 
 	nexthop = prefix_nexthop(p);
+	peer = prefix_peer(p);
 	bzero(&rib, sizeof(rib));
 	rib.age = getmonotime() - p->lastchange;
 	rib.local_pref = asp->lpref;
 	rib.med = asp->med;
 	rib.weight = asp->weight;
-	strlcpy(rib.descr, prefix_peer(p)->conf.descr, sizeof(rib.descr));
-	memcpy(&rib.remote_addr, &prefix_peer(p)->remote_addr,
+	strlcpy(rib.descr, peer->conf.descr, sizeof(rib.descr));
+	memcpy(&rib.remote_addr, &peer->remote_addr,
 	    sizeof(rib.remote_addr));
-	rib.remote_id = prefix_peer(p)->remote_bgpid;
+	rib.remote_id = peer->remote_bgpid;
 	if (nexthop != NULL) {
 		memcpy(&rib.true_nexthop, &nexthop->true_nexthop,
 		    sizeof(rib.true_nexthop));
@@ -2334,7 +2402,7 @@ rde_dump_rib_as(struct prefix *p, struct rde_aspath *asp, pid_t pid, int flags)
 	re = prefix_re(p);
 	if (re != NULL && re->active == p)
 		rib.flags |= F_PREF_ACTIVE;
-	if (!prefix_peer(p)->conf.ebgp)
+	if (!peer->conf.ebgp)
 		rib.flags |= F_PREF_INTERNAL;
 	if (asp->flags & F_PREFIX_ANNOUNCED)
 		rib.flags |= F_PREF_ANNOUNCE;
@@ -2344,9 +2412,20 @@ rde_dump_rib_as(struct prefix *p, struct rde_aspath *asp, pid_t pid, int flags)
 		rib.flags &= ~F_PREF_ELIGIBLE;
 	if (asp->flags & F_ATTR_PARSE_ERR)
 		rib.flags |= F_PREF_INVALID;
-	staletime = prefix_peer(p)->staletime[p->pt->aid];
+	staletime = peer->staletime[p->pt->aid];
 	if (staletime && p->lastchange <= staletime)
 		rib.flags |= F_PREF_STALE;
+	if (!adjout) {
+		if (peer_has_add_path(peer, p->pt->aid, CAPA_AP_RECV)) {
+			rib.path_id = p->path_id;
+			rib.flags |= F_PREF_PATH_ID;
+		}
+	} else {
+		if (peer_has_add_path(peer, p->pt->aid, CAPA_AP_SEND)) {
+			rib.path_id = 0;	/* XXX add-path send */
+			rib.flags |= F_PREF_PATH_ID;
+		}
+	}
 	aslen = aspath_length(asp->aspath);
 
 	if ((wbuf = imsg_create(ibuf_se_ctl, IMSG_CTL_SHOW_RIB, 0, pid,
@@ -2411,7 +2490,7 @@ rde_match_peer(struct rde_peer *p, struct ctl_neighbor *n)
 }
 
 static void
-rde_dump_filter(struct prefix *p, struct ctl_show_rib_request *req)
+rde_dump_filter(struct prefix *p, struct ctl_show_rib_request *req, int adjout)
 {
 	struct rde_aspath	*asp;
 	struct rib_entry	*re;
@@ -2428,6 +2507,12 @@ rde_dump_filter(struct prefix *p, struct ctl_show_rib_request *req)
 	if ((req->flags & F_CTL_INVALID) &&
 	    (asp->flags & F_ATTR_PARSE_ERR) == 0)
 		return;
+	/*
+	 * XXX handle out specially since then we want to match against our
+	 * path ids.
+	 */
+	if ((req->flags & F_CTL_HAS_PATHID) && req->path_id != p->path_id)
+		return;
 	if (req->as.type != AS_UNDEF &&
 	    !aspath_match(asp->aspath, &req->as, 0))
 		return;
@@ -2438,7 +2523,7 @@ rde_dump_filter(struct prefix *p, struct ctl_show_rib_request *req)
 	}
 	if (!ovs_match(p, req->flags))
 		return;
-	rde_dump_rib_as(p, asp, req->pid, req->flags);
+	rde_dump_rib_as(p, asp, req->pid, req->flags, adjout);
 }
 
 static void
@@ -2448,7 +2533,7 @@ rde_dump_upcall(struct rib_entry *re, void *ptr)
 	struct prefix		*p;
 
 	LIST_FOREACH(p, &re->prefix_h, entry.list.rib)
-		rde_dump_filter(p, &ctx->req);
+		rde_dump_filter(p, &ctx->req, 0);
 }
 
 static void
@@ -2469,14 +2554,14 @@ rde_dump_prefix_upcall(struct rib_entry *re, void *ptr)
 		if (!prefix_compare(&ctx->req.prefix, &addr,
 		    ctx->req.prefixlen))
 			LIST_FOREACH(p, &re->prefix_h, entry.list.rib)
-				rde_dump_filter(p, &ctx->req);
+				rde_dump_filter(p, &ctx->req, 0);
 	} else {
 		if (ctx->req.prefixlen < pt->prefixlen)
 			return;
 		if (!prefix_compare(&addr, &ctx->req.prefix,
 		    pt->prefixlen))
 			LIST_FOREACH(p, &re->prefix_h, entry.list.rib)
-				rde_dump_filter(p, &ctx->req);
+				rde_dump_filter(p, &ctx->req, 0);
 	}
 }
 
@@ -2487,7 +2572,7 @@ rde_dump_adjout_upcall(struct prefix *p, void *ptr)
 
 	if (p->flags & (PREFIX_FLAG_WITHDRAW | PREFIX_FLAG_DEAD))
 		return;
-	rde_dump_filter(p, &ctx->req);
+	rde_dump_filter(p, &ctx->req, 1);
 }
 
 static void
@@ -2507,13 +2592,13 @@ rde_dump_adjout_prefix_upcall(struct prefix *p, void *ptr)
 			return;
 		if (!prefix_compare(&ctx->req.prefix, &addr,
 		    ctx->req.prefixlen))
-			rde_dump_filter(p, &ctx->req);
+			rde_dump_filter(p, &ctx->req, 1);
 	} else {
 		if (ctx->req.prefixlen < p->pt->prefixlen)
 			return;
 		if (!prefix_compare(&addr, &ctx->req.prefix,
 		    p->pt->prefixlen))
-			rde_dump_filter(p, &ctx->req);
+			rde_dump_filter(p, &ctx->req, 1);
 	}
 }
 
@@ -3580,11 +3665,12 @@ rde_softreconfig_in(struct rib_entry *re, void *bula)
 
 			if (action == ACTION_ALLOW) {
 				/* update Local-RIB */
-				prefix_update(rib, peer, &state, &prefix,
-				    pt->prefixlen, p->validation_state);
+				prefix_update(rib, peer, p->path_id, &state,
+				    &prefix, pt->prefixlen,
+				    p->validation_state);
 			} else if (action == ACTION_DENY) {
 				/* remove from Local-RIB */
-				prefix_withdraw(rib, peer, &prefix,
+				prefix_withdraw(rib, peer, p->path_id, &prefix,
 				    pt->prefixlen);
 			}
 
@@ -3724,11 +3810,12 @@ rde_roa_softreload(struct rib_entry *re, void *bula)
 
 			if (action == ACTION_ALLOW) {
 				/* update Local-RIB */
-				prefix_update(rib, peer, &state, &prefix,
-				    pt->prefixlen, p->validation_state);
+				prefix_update(rib, peer, p->path_id, &state,
+				    &prefix, pt->prefixlen,
+				    p->validation_state);
 			} else if (action == ACTION_DENY) {
 				/* remove from Local-RIB */
-				prefix_withdraw(rib, peer, &prefix,
+				prefix_withdraw(rib, peer, p->path_id, &prefix,
 				    pt->prefixlen);
 			}
 
@@ -3952,7 +4039,7 @@ network_add(struct network_config *nc, struct filterstate *state)
 
 	vstate = rde_roa_validity(&rde_roa, &nc->prefix,
 	    nc->prefixlen, aspath_origin(state->aspath.aspath));
-	if (prefix_update(rib_byid(RIB_ADJ_IN), peerself, state, &nc->prefix,
+	if (prefix_update(rib_byid(RIB_ADJ_IN), peerself, 0, state, &nc->prefix,
 	    nc->prefixlen, vstate) == 1)
 		peerself->prefix_cnt++;
 	for (i = RIB_LOC_START; i < rib_size; i++) {
@@ -3962,7 +4049,7 @@ network_add(struct network_config *nc, struct filterstate *state)
 		rde_update_log("announce", i, peerself,
 		    state->nexthop ? &state->nexthop->exit_nexthop : NULL,
 		    &nc->prefix, nc->prefixlen);
-		prefix_update(rib, peerself, state, &nc->prefix,
+		prefix_update(rib, peerself, 0, state, &nc->prefix,
 		    nc->prefixlen, vstate);
 	}
 	filterset_free(&nc->attrset);
@@ -4022,12 +4109,12 @@ network_delete(struct network_config *nc)
 		struct rib *rib = rib_byid(i);
 		if (rib == NULL)
 			continue;
-		if (prefix_withdraw(rib, peerself, &nc->prefix,
+		if (prefix_withdraw(rib, peerself, 0, &nc->prefix,
 		    nc->prefixlen))
 			rde_update_log("withdraw announce", i, peerself,
 			    NULL, &nc->prefix, nc->prefixlen);
 	}
-	if (prefix_withdraw(rib_byid(RIB_ADJ_IN), peerself, &nc->prefix,
+	if (prefix_withdraw(rib_byid(RIB_ADJ_IN), peerself, 0, &nc->prefix,
 	    nc->prefixlen))
 		peerself->prefix_cnt--;
 }
@@ -4074,7 +4161,7 @@ network_flush_upcall(struct rib_entry *re, void *ptr)
 	u_int32_t i;
 	u_int8_t prefixlen;
 
-	p = prefix_bypeer(re, peerself);
+	p = prefix_bypeer(re, peerself, 0);
 	if (p == NULL)
 		return;
 	if ((prefix_aspath(p)->flags & F_ANN_DYNAMIC) != F_ANN_DYNAMIC)
@@ -4087,12 +4174,12 @@ network_flush_upcall(struct rib_entry *re, void *ptr)
 		struct rib *rib = rib_byid(i);
 		if (rib == NULL)
 			continue;
-		if (prefix_withdraw(rib, peerself, &addr, prefixlen) == 1)
+		if (prefix_withdraw(rib, peerself, 0, &addr, prefixlen) == 1)
 			rde_update_log("flush announce", i, peerself,
 			    NULL, &addr, prefixlen);
 	}
 
-	if (prefix_withdraw(rib_byid(RIB_ADJ_IN), peerself, &addr,
+	if (prefix_withdraw(rib_byid(RIB_ADJ_IN), peerself, 0, &addr,
 	    prefixlen) == 1)
 		peerself->prefix_cnt--;
 }