Adjust handling of RIB_GENERIC_ADDPATH MRT messages. Parse it the way

OpenBGPD and GoBGP dump so that it works with all the MRT implementations
out there supporting this.
While there do some additional minor cleanup.
OK deraadt@

diff --git a/usr.sbin/bgpctl/mrtparser.c b/usr.sbin/bgpctl/mrtparser.c
index 3297ed5..5a0d39e 100644 (file)
--- a/usr.sbin/bgpctl/mrtparser.c
+++ b/usr.sbin/bgpctl/mrtparser.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: mrtparser.c,v 1.15 2021/07/27 07:42:37 claudio Exp $ */
+/*     $OpenBSD: mrtparser.c,v 1.16 2021/09/22 18:17:49 claudio Exp $ */
 /*
  * Copyright (c) 2011 Claudio Jeker <claudio@openbsd.org>
  *
@@ -103,10 +103,8 @@ mrt_parse(int fd, struct mrt_parser *p, int verbose)
        struct mrt_bgp_state    *s;
        struct mrt_bgp_msg      *m;
        void                    *msg;
-       int                      addpath;
 
        while ((msg = mrt_read_msg(fd, &h))) {
-               addpath = 0;
                switch (ntohs(h.type)) {
                case MSG_NULL:
                case MSG_START:
@@ -376,7 +374,7 @@ mrt_parse_v2_rib(struct mrt_hdr *hdr, void *msg, int verbose)
        u_int32_t       snum, path_id = 0;
        u_int16_t       cnt, i, afi;
        u_int8_t        safi, aid;
-       int             ret, addpath = 0;
+       int             ret;
 
        if (len < sizeof(snum) + 1)
                return NULL;
@@ -417,6 +415,11 @@ mrt_parse_v2_rib(struct mrt_hdr *hdr, void *msg, int verbose)
                        goto fail;
                break;
        case MRT_DUMP_V2_RIB_GENERIC_ADDPATH:
+               /*
+                * RFC8050 handling for add-path has special handling for
+                * RIB_GENERIC_ADDPATH but nobody implements it that way.
+                * So just use the same way as for the other _ADDPATH types.
+                */
                r->add_path = 1;
                /* FALLTHROUGH */
        case MRT_DUMP_V2_RIB_GENERIC:
@@ -434,16 +437,6 @@ mrt_parse_v2_rib(struct mrt_hdr *hdr, void *msg, int verbose)
                if ((aid = mrt_afi2aid(afi, safi, verbose)) == AID_UNSPEC)
                        goto fail;
                
-               /* RFC8050 handling for add-path */
-               if (r->add_path) {
-                       if (len < sizeof(path_id))
-                               goto fail;
-                       memcpy(&path_id, b, sizeof(path_id));
-                       b += sizeof(path_id);
-                       len -= sizeof(path_id);
-                       path_id = ntohl(path_id);
-               }
-
                /* prefix */
                ret = mrt_extract_prefix(b, len, aid, &r->prefix,
                    &r->prefixlen, verbose);
@@ -487,12 +480,9 @@ mrt_parse_v2_rib(struct mrt_hdr *hdr, void *msg, int verbose)
                len -= sizeof(otm);
                entries[i].originated = ntohl(otm);
 
-               /* RFC8050 handling for add-path */
-               if (r->add_path &&
-                   ntohs(hdr->subtype) != MRT_DUMP_V2_RIB_GENERIC_ADDPATH) {
+               if (r->add_path) {
                        if (len < sizeof(path_id) + sizeof(alen))
                                goto fail;
-                       addpath = 0;
                        memcpy(&path_id, b, sizeof(path_id));
                        b += sizeof(path_id);
                        len -= sizeof(path_id);