Before adding a prefix to the Adj-RIB-Out modify the attributes to the

ones being sent out. Mainly prepend the ASPATH if needed and also change
the nexthop to the one being sent.
This should make the `bgpctl show rib out` output show the values the
peer receives.
OK job@

diff --git a/usr.sbin/bgpd/rde_update.c b/usr.sbin/bgpd/rde_update.c
index 66abee9..3296227 100644 (file)
--- a/usr.sbin/bgpd/rde_update.c
+++ b/usr.sbin/bgpd/rde_update.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: rde_update.c,v 1.129 2021/05/27 14:32:08 claudio Exp $ */
+/*     $OpenBSD: rde_update.c,v 1.130 2021/06/17 08:14:50 claudio Exp $ */
 
 /*
  * Copyright (c) 2004 Claudio Jeker <claudio@openbsd.org>
@@ -45,6 +45,8 @@ static struct community       comm_no_expsubconfed = {
        .data2 = COMMUNITY_NO_EXPSUBCONFED
 };
 
+static void up_prep_adjout(struct rde_peer *, struct filterstate *, u_int8_t);
+
 static int
 up_test_update(struct rde_peer *peer, struct prefix *p)
 {
@@ -166,6 +168,8 @@ again:
                        goto again;
                }
 
+               up_prep_adjout(peer, &state, addr.aid);
+
                /* only send update if path changed */
                if (prefix_adjout_update(peer, &state, &addr,
                    new->pt->prefixlen, prefix_vstate(new)) == 1) {
@@ -225,6 +229,8 @@ up_generate_default(struct filter_head *rules, struct rde_peer *peer,
                return;
        }
 
+       up_prep_adjout(peer, &state, addr.aid);
+
        if (prefix_adjout_update(peer, &state, &addr, 0, ROA_NOTFOUND) == 1) {
                peer->prefix_out_cnt++;
                peer->up_nlricnt++;
@@ -244,7 +250,6 @@ up_generate_default(struct filter_head *rules, struct rde_peer *peer,
        }
 }
 
-/* only for IPv4 */
 static struct bgpd_addr *
 up_get_nexthop(struct rde_peer *peer, struct filterstate *state, u_int8_t aid)
 {
@@ -325,6 +330,32 @@ up_get_nexthop(struct rde_peer *peer, struct filterstate *state, u_int8_t aid)
        }
 }
 
+static void
+up_prep_adjout(struct rde_peer *peer, struct filterstate *state, u_int8_t aid)
+{
+       struct bgpd_addr *nexthop;
+       struct nexthop *nh;
+       u_char *np;
+       u_int16_t nl;
+
+       /* prepend local AS number for eBGP sessions. */
+       if (peer->conf.ebgp && (peer->flags & PEERFLAG_TRANS_AS) == 0) {
+               u_int32_t prep_as = peer->conf.local_as;
+               np = aspath_prepend(state->aspath.aspath, prep_as, 1, &nl);
+               aspath_put(state->aspath.aspath);
+               state->aspath.aspath = aspath_get(np, nl);
+               free(np);
+       }
+
+       /* update nexthop */
+       nexthop = up_get_nexthop(peer, state, aid);
+       nh = nexthop_get(nexthop);
+       nexthop_unref(state->nexthop);
+       state->nexthop = nh;
+       state->nhflags = 0;
+}
+
+
 static int
 up_generate_attr(u_char *buf, int len, struct rde_peer *peer,
     struct filterstate *state, u_int8_t aid)
@@ -334,7 +365,7 @@ up_generate_attr(u_char *buf, int len, struct rde_peer *peer,
        struct attr     *oa = NULL, *newaggr = NULL;
        u_char          *pdata;
        u_int32_t        tmp32;
-       in_addr_t        nexthop;
+       struct bgpd_addr *nexthop;
        int              flags, r, neednewpath = 0;
        u_int16_t        wlen = 0, plen;
        u_int8_t         oalen = 0, type;
@@ -363,13 +394,8 @@ up_generate_attr(u_char *buf, int len, struct rde_peer *peer,
                                return (-1);
                        break;
                case ATTR_ASPATH:
-                       if (!peer->conf.ebgp ||
-                           peer->flags & PEERFLAG_TRANS_AS)
-                               pdata = aspath_prepend(asp->aspath,
-                                   peer->conf.local_as, 0, &plen);
-                       else
-                               pdata = aspath_prepend(asp->aspath,
-                                   peer->conf.local_as, 1, &plen);
+                       plen = aspath_length(asp->aspath);
+                       pdata = aspath_dump(asp->aspath);
 
                        if (!peer_has_as4byte(peer))
                                pdata = aspath_deflate(pdata, &plen,
@@ -378,16 +404,16 @@ up_generate_attr(u_char *buf, int len, struct rde_peer *peer,
                        if ((r = attr_write(buf + wlen, len, ATTR_WELL_KNOWN,
                            ATTR_ASPATH, pdata, plen)) == -1)
                                return (-1);
-                       free(pdata);
+                       if (!peer_has_as4byte(peer))
+                               free(pdata);
                        break;
                case ATTR_NEXTHOP:
                        switch (aid) {
                        case AID_INET:
-                               nexthop =
-                                   up_get_nexthop(peer, state, aid)->v4.s_addr;
+                               nexthop = &state->nexthop->exit_nexthop;
                                if ((r = attr_write(buf + wlen, len,
-                                   ATTR_WELL_KNOWN, ATTR_NEXTHOP, &nexthop,
-                                   4)) == -1)
+                                   ATTR_WELL_KNOWN, ATTR_NEXTHOP,
+                                   &nexthop->v4.s_addr, 4)) == -1)
                                        return (-1);
                                break;
                        default:
@@ -442,13 +468,9 @@ up_generate_attr(u_char *buf, int len, struct rde_peer *peer,
                 */
                case ATTR_AS4_PATH:
                        if (neednewpath) {
-                               if (!peer->conf.ebgp ||
-                                   peer->flags & PEERFLAG_TRANS_AS)
-                                       pdata = aspath_prepend(asp->aspath,
-                                       peer->conf.local_as, 0, &plen);
-                               else
-                                       pdata = aspath_prepend(asp->aspath,
-                                           peer->conf.local_as, 1, &plen);
+                               plen = aspath_length(asp->aspath);
+                               pdata = aspath_dump(asp->aspath);
+
                                flags = ATTR_OPTIONAL|ATTR_TRANSITIVE;
                                if (!(asp->flags & F_PREFIX_ANNOUNCED))
                                        flags |= ATTR_PARTIAL;
@@ -457,7 +479,6 @@ up_generate_attr(u_char *buf, int len, struct rde_peer *peer,
                                else if ((r = attr_write(buf + wlen, len, flags,
                                    ATTR_AS4_PATH, pdata, plen)) == -1)
                                        return (-1);
-                               free(pdata);
                        }
                        break;
                case ATTR_AS4_AGGREGATOR:
@@ -786,7 +807,7 @@ up_generate_mp_reach(u_char *buf, int len, struct rde_peer *peer,
 
                /* write nexthop */
                attrbuf += 4;
-               nexthop = up_get_nexthop(peer, state, aid);
+               nexthop = &state->nexthop->exit_nexthop;
                memcpy(attrbuf, &nexthop->v6, sizeof(struct in6_addr));
                break;
        case AID_VPN_IPv4:
@@ -804,7 +825,7 @@ up_generate_mp_reach(u_char *buf, int len, struct rde_peer *peer,
 
                /* write nexthop */
                attrbuf += 12;
-               nexthop = up_get_nexthop(peer, state, aid);
+               nexthop = &state->nexthop->exit_nexthop;
                memcpy(attrbuf, &nexthop->v4, sizeof(struct in_addr));
                break;
        case AID_VPN_IPv6:
@@ -822,7 +843,7 @@ up_generate_mp_reach(u_char *buf, int len, struct rde_peer *peer,
 
                /* write nexthop */
                attrbuf += 12;
-               nexthop = up_get_nexthop(peer, state, aid);
+               nexthop = &state->nexthop->exit_nexthop;
                memcpy(attrbuf, &nexthop->v6, sizeof(struct in6_addr));
                break;
        default: