ldpd/hello.c

   1 /*      $OpenBSD$ */
   2
   3 /*
   4  * Copyright (c) 2013, 2016 Renato Westphal <renato@openbsd.org>
   5  * Copyright (c) 2009 Michele Marchetto <michele@openbsd.org>
   6  *
   7  * Permission to use, copy, modify, and distribute this software for any
   8  * purpose with or without fee is hereby granted, provided that the above
   9  * copyright notice and this permission notice appear in all copies.
  10  *
  11  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  13  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  17  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 #include <zebra.h>
  21
  22 #include "ldpd.h"
  23 #include "ldpe.h"
  24 #include "log.h"
  25 #include "ldp_debug.h"
  26
  27 static int      gen_hello_prms_tlv(struct ibuf *buf, uint16_t, uint16_t);
  28 static int      gen_opt4_hello_prms_tlv(struct ibuf *, uint16_t, uint32_t);
  29 static int      gen_opt16_hello_prms_tlv(struct ibuf *, uint16_t, uint8_t *);
  30 static int      gen_ds_hello_prms_tlv(struct ibuf *, uint32_t);
  31 static int      tlv_decode_hello_prms(char *, uint16_t, uint16_t *, uint16_t *);
  32 static int      tlv_decode_opt_hello_prms(char *, uint16_t, int *, int,
  33                     union ldpd_addr *, uint32_t *, uint16_t *);
  34
  35 int
  36 send_hello(enum hello_type type, struct iface_af *ia, struct tnbr *tnbr)
  37 {
  38         int                      af;
  39         union ldpd_addr          dst;
  40         uint16_t                 size, holdtime = 0, flags = 0;
  41         int                      fd = 0;
  42         struct ibuf             *buf;
  43         int                      err = 0;
  44
  45         switch (type) {
  46         case HELLO_LINK:
  47                 af = ia->af;
  48                 holdtime = if_get_hello_holdtime(ia);
  49                 flags = 0;
  50                 fd = (ldp_af_global_get(&global, af))->ldp_disc_socket;
  51
  52                 /* multicast destination address */
  53                 switch (af) {
  54                 case AF_INET:
  55                         if (!(leconf->ipv4.flags & F_LDPD_AF_NO_GTSM))
  56                                 flags |= F_HELLO_GTSM;
  57                         dst.v4 = global.mcast_addr_v4;
  58                         break;
  59                 case AF_INET6:
  60                         dst.v6 = global.mcast_addr_v6;
  61                         break;
  62                 default:
  63                         fatalx("send_hello: unknown af");
  64                 }
  65                 break;
  66         case HELLO_TARGETED:
  67                 af = tnbr->af;
  68                 holdtime = tnbr_get_hello_holdtime(tnbr);
  69                 flags = F_HELLO_TARGETED;
  70                 if ((tnbr->flags & F_TNBR_CONFIGURED) || tnbr->pw_count)
  71                         flags |= F_HELLO_REQ_TARG;
  72                 fd = (ldp_af_global_get(&global, af))->ldp_edisc_socket;
  73
  74                 /* unicast destination address */
  75                 dst = tnbr->addr;
  76                 break;
  77         default:
  78                 fatalx("send_hello: unknown hello type");
  79         }
  80
  81         /* calculate message size */
  82         size = LDP_HDR_SIZE + LDP_MSG_SIZE + sizeof(struct hello_prms_tlv);
  83         switch (af) {
  84         case AF_INET:
  85                 size += sizeof(struct hello_prms_opt4_tlv);
  86                 break;
  87         case AF_INET6:
  88                 size += sizeof(struct hello_prms_opt16_tlv);
  89                 break;
  90         default:
  91                 fatalx("send_hello: unknown af");
  92         }
  93         size += sizeof(struct hello_prms_opt4_tlv);
  94         if (ldp_is_dual_stack(leconf))
  95                 size += sizeof(struct hello_prms_opt4_tlv);
  96
  97         /* generate message */
  98         if ((buf = ibuf_open(size)) == NULL)
  99                 fatal(__func__);
 100
 101         err |= gen_ldp_hdr(buf, size);
 102         size -= LDP_HDR_SIZE;
 103         err |= gen_msg_hdr(buf, MSG_TYPE_HELLO, size);
 104         err |= gen_hello_prms_tlv(buf, holdtime, flags);
 105
 106         /*
 107          * RFC 7552 - Section 6.1:
 108          * "An LSR MUST include only the transport address whose address
 109          * family is the same as that of the IP packet carrying the Hello
 110          * message".
 111          */
 112         switch (af) {
 113         case AF_INET:
 114                 err |= gen_opt4_hello_prms_tlv(buf, TLV_TYPE_IPV4TRANSADDR,
 115                     leconf->ipv4.trans_addr.v4.s_addr);
 116                 break;
 117         case AF_INET6:
 118                 err |= gen_opt16_hello_prms_tlv(buf, TLV_TYPE_IPV6TRANSADDR,
 119                     leconf->ipv6.trans_addr.v6.s6_addr);
 120                 break;
 121         default:
 122                 fatalx("send_hello: unknown af");
 123         }
 124
 125         err |= gen_opt4_hello_prms_tlv(buf, TLV_TYPE_CONFIG,
 126             htonl(global.conf_seqnum));
 127
 128         /*
 129          * RFC 7552 - Section 6.1.1:
 130          * "A Dual-stack LSR (i.e., an LSR supporting Dual-stack LDP for a peer)
 131          * MUST include the Dual-Stack capability TLV in all of its LDP Hellos".
 132          */
 133         if (ldp_is_dual_stack(leconf))
 134                 err |= gen_ds_hello_prms_tlv(buf, leconf->trans_pref);
 135
 136         if (err) {
 137                 ibuf_free(buf);
 138                 return (-1);
 139         }
 140
 141         switch (type) {
 142         case HELLO_LINK:
 143                 debug_hello_send("iface %s (%s) holdtime %u", ia->iface->name,
 144                     af_name(ia->af), holdtime);
 145                 break;
 146         case HELLO_TARGETED:
 147                 debug_hello_send("targeted-neighbor %s (%s) holdtime %u",
 148                     log_addr(tnbr->af, &tnbr->addr), af_name(tnbr->af),
 149                     holdtime);
 150                 break;
 151         default:
 152                 fatalx("send_hello: unknown hello type");
 153         }
 154
 155         send_packet(fd, af, &dst, ia, buf->buf, buf->wpos);
 156         ibuf_free(buf);
 157
 158         return (0);
 159 }
 160
 161 void
 162 recv_hello(struct in_addr lsr_id, struct ldp_msg *msg, int af,
 163     union ldpd_addr *src, struct iface *iface, int multicast, char *buf,
 164     uint16_t len)
 165 {
 166         struct adj              *adj = NULL;
 167         struct nbr              *nbr, *nbrt;
 168         uint16_t                 holdtime = 0, flags = 0;
 169         int                      tlvs_rcvd;
 170         int                      ds_tlv;
 171         union ldpd_addr          trans_addr;
 172         uint32_t                 scope_id = 0;
 173         uint32_t                 conf_seqnum;
 174         uint16_t                 trans_pref;
 175         int                      r;
 176         struct hello_source      source;
 177         struct iface_af         *ia = NULL;
 178         struct tnbr             *tnbr = NULL;
 179
 180         r = tlv_decode_hello_prms(buf, len, &holdtime, &flags);
 181         if (r == -1) {
 182                 log_debug("%s: lsr-id %s: failed to decode params", __func__,
 183                     inet_ntoa(lsr_id));
 184                 return;
 185         }
 186         /* safety checks */
 187         if (holdtime != 0 && holdtime < MIN_HOLDTIME) {
 188                 log_debug("%s: lsr-id %s: invalid hello holdtime (%u)",
 189                     __func__, inet_ntoa(lsr_id), holdtime);
 190                 return;
 191         }
 192         if (multicast && (flags & F_HELLO_TARGETED)) {
 193                 log_debug("%s: lsr-id %s: multicast targeted hello", __func__,
 194                     inet_ntoa(lsr_id));
 195                 return;
 196         }
 197         if (!multicast && !((flags & F_HELLO_TARGETED))) {
 198                 log_debug("%s: lsr-id %s: unicast link hello", __func__,
 199                     inet_ntoa(lsr_id));
 200                 return;
 201         }
 202         buf += r;
 203         len -= r;
 204
 205         r = tlv_decode_opt_hello_prms(buf, len, &tlvs_rcvd, af, &trans_addr,
 206             &conf_seqnum, &trans_pref);
 207         if (r == -1) {
 208                 log_debug("%s: lsr-id %s: failed to decode optional params",
 209                     __func__, inet_ntoa(lsr_id));
 210                 return;
 211         }
 212         if (r != len) {
 213                 log_debug("%s: lsr-id %s: unexpected data in message",
 214                     __func__, inet_ntoa(lsr_id));
 215                 return;
 216         }
 217
 218         /* implicit transport address */
 219         if (!(tlvs_rcvd & F_HELLO_TLV_RCVD_ADDR))
 220                 trans_addr = *src;
 221         if (bad_addr(af, &trans_addr)) {
 222                 log_debug("%s: lsr-id %s: invalid transport address %s",
 223                     __func__, inet_ntoa(lsr_id), log_addr(af, &trans_addr));
 224                 return;
 225         }
 226         if (af == AF_INET6 && IN6_IS_SCOPE_EMBED(&trans_addr.v6)) {
 227                 /*
 228                  * RFC 7552 - Section 6.1:
 229                  * "An LSR MUST use a global unicast IPv6 address in an IPv6
 230                  * Transport Address optional object of outgoing targeted
 231                  * Hellos and check for the same in incoming targeted Hellos
 232                  * (i.e., MUST discard the targeted Hello if it failed the
 233                  * check)".
 234                  */
 235                 if (flags & F_HELLO_TARGETED) {
 236                         log_debug("%s: lsr-id %s: invalid targeted hello "
 237                             "transport address %s", __func__, inet_ntoa(lsr_id),
 238                              log_addr(af, &trans_addr));
 239                         return;
 240                 }
 241                 scope_id = iface->ifindex;
 242         }
 243
 244         memset(&source, 0, sizeof(source));
 245         if (flags & F_HELLO_TARGETED) {
 246                 /*
 247                  * RFC 7552 - Section 5.2:
 248                 * "The link-local IPv6 addresses MUST NOT be used as the
 249                 * targeted LDP Hello packet's source or destination addresses".
 250                 */
 251                 if (af == AF_INET6 && IN6_IS_SCOPE_EMBED(&src->v6)) {
 252                         log_debug("%s: lsr-id %s: targeted hello with "
 253                             "link-local source address", __func__,
 254                             inet_ntoa(lsr_id));
 255                         return;
 256                 }
 257
 258                 tnbr = tnbr_find(leconf, af, src);
 259
 260                 /* remove the dynamic tnbr if the 'R' bit was cleared */
 261                 if (tnbr && (tnbr->flags & F_TNBR_DYNAMIC) &&
 262                     !((flags & F_HELLO_REQ_TARG))) {
 263                         tnbr->flags &= ~F_TNBR_DYNAMIC;
 264                         tnbr = tnbr_check(leconf, tnbr);
 265                 }
 266
 267                 if (!tnbr) {
 268                         if (!((flags & F_HELLO_REQ_TARG) &&
 269                             ((ldp_af_conf_get(leconf, af))->flags &
 270                             F_LDPD_AF_THELLO_ACCEPT)))
 271                                 return;
 272
 273                         tnbr = tnbr_new(af, src);
 274                         tnbr->flags |= F_TNBR_DYNAMIC;
 275                         tnbr_update(tnbr);
 276                         RB_INSERT(tnbr_head, &leconf->tnbr_tree, tnbr);
 277                 }
 278
 279                 source.type = HELLO_TARGETED;
 280                 source.target = tnbr;
 281         } else {
 282                 ia = iface_af_get(iface, af);
 283                 source.type = HELLO_LINK;
 284                 source.link.ia = ia;
 285                 source.link.src_addr = *src;
 286         }
 287
 288         adj = adj_find(&source);
 289         nbr = nbr_find_ldpid(lsr_id.s_addr);
 290
 291         /* check dual-stack tlv */
 292         ds_tlv = (tlvs_rcvd & F_HELLO_TLV_RCVD_DS) ? 1 : 0;
 293         if (ds_tlv && trans_pref != leconf->trans_pref) {
 294                 /*
 295                  * RFC 7552 - Section 6.1.1:
 296                  * "If the Dual-Stack capability TLV is present and the remote
 297                  * preference does not match the local preference (or does not
 298                  * get recognized), then the LSR MUST discard the Hello message
 299                  * and log an error.
 300                  * If an LDP session was already in place, then the LSR MUST
 301                  * send a fatal Notification message with status code of
 302                  * 'Transport Connection Mismatch' and reset the session".
 303                  */
 304                 log_debug("%s: lsr-id %s: remote transport preference does not "
 305                     "match the local preference", __func__, inet_ntoa(lsr_id));
 306                 if (nbr)
 307                         session_shutdown(nbr, S_TRANS_MISMTCH, msg->id,
 308                             msg->type);
 309                 if (adj)
 310                         adj_del(adj, S_SHUTDOWN);
 311                 return;
 312         }
 313
 314         /*
 315          * Check for noncompliant dual-stack neighbor according to
 316          * RFC 7552 section 6.1.1.
 317          */
 318         if (nbr && !ds_tlv) {
 319                 switch (af) {
 320                 case AF_INET:
 321                         if (nbr_adj_count(nbr, AF_INET6) > 0) {
 322                                 session_shutdown(nbr, S_DS_NONCMPLNCE,
 323                                     msg->id, msg->type);
 324                                 return;
 325                         }
 326                         break;
 327                 case AF_INET6:
 328                         if (nbr_adj_count(nbr, AF_INET) > 0) {
 329                                 session_shutdown(nbr, S_DS_NONCMPLNCE,
 330                                     msg->id, msg->type);
 331                                 return;
 332                         }
 333                         break;
 334                 default:
 335                         fatalx("recv_hello: unknown af");
 336                 }
 337         }
 338
 339         /*
 340          * Protections against misconfigured networks and buggy implementations.
 341          */
 342         if (nbr && nbr->af == af &&
 343             (ldp_addrcmp(af, &nbr->raddr, &trans_addr) ||
 344             nbr->raddr_scope != scope_id)) {
 345                 log_warnx("%s: lsr-id %s: hello packet advertising a different "
 346                     "transport address", __func__, inet_ntoa(lsr_id));
 347                 if (adj)
 348                         adj_del(adj, S_SHUTDOWN);
 349                 return;
 350         }
 351         if (nbr == NULL) {
 352                 nbrt = nbr_find_addr(af, &trans_addr);
 353                 if (nbrt) {
 354                         log_debug("%s: transport address %s is already being "
 355                             "used by lsr-id %s", __func__, log_addr(af,
 356                             &trans_addr), inet_ntoa(nbrt->id));
 357                         if (adj)
 358                                 adj_del(adj, S_SHUTDOWN);
 359                         return;
 360                 }
 361         }
 362
 363         if (adj == NULL) {
 364                 adj = adj_new(lsr_id, &source, &trans_addr);
 365                 if (nbr) {
 366                         adj->nbr = nbr;
 367                         RB_INSERT(nbr_adj_head, &nbr->adj_tree, adj);
 368                 }
 369         }
 370
 371         /*
 372          * If the hello adjacency's address-family doesn't match the local
 373          * preference, then an adjacency is still created but we don't attempt
 374          * to start an LDP session.
 375          */
 376         if (nbr == NULL && (!ds_tlv ||
 377             ((trans_pref == DUAL_STACK_LDPOV4 && af == AF_INET) ||
 378             (trans_pref == DUAL_STACK_LDPOV6 && af == AF_INET6))))
 379                 nbr = nbr_new(lsr_id, af, ds_tlv, &trans_addr, scope_id);
 380
 381         /* dynamic LDPv4 GTSM negotiation as per RFC 6720 */
 382         if (nbr) {
 383                 if (flags & F_HELLO_GTSM)
 384                         nbr->flags |= F_NBR_GTSM_NEGOTIATED;
 385                 else
 386                         nbr->flags &= ~F_NBR_GTSM_NEGOTIATED;
 387         }
 388
 389         /* update neighbor's configuration sequence number */
 390         if (nbr && (tlvs_rcvd & F_HELLO_TLV_RCVD_CONF)) {
 391                 if (conf_seqnum > nbr->conf_seqnum &&
 392                     nbr_pending_idtimer(nbr))
 393                         nbr_stop_idtimer(nbr);
 394                 nbr->conf_seqnum = conf_seqnum;
 395         }
 396
 397         /* always update the holdtime to properly handle runtime changes */
 398         switch (source.type) {
 399         case HELLO_LINK:
 400                 if (holdtime == 0)
 401                         holdtime = LINK_DFLT_HOLDTIME;
 402
 403                 adj->holdtime = min(if_get_hello_holdtime(ia), holdtime);
 404                 break;
 405         case HELLO_TARGETED:
 406                 if (holdtime == 0)
 407                         holdtime = TARGETED_DFLT_HOLDTIME;
 408
 409                 adj->holdtime = min(tnbr_get_hello_holdtime(tnbr), holdtime);
 410         }
 411         if (adj->holdtime != INFINITE_HOLDTIME)
 412                 adj_start_itimer(adj);
 413         else
 414                 adj_stop_itimer(adj);
 415
 416         debug_hello_recv("%s lsr-id %s transport-address %s holdtime %u%s",
 417             log_hello_src(&source), inet_ntoa(lsr_id), log_addr(af, &trans_addr),
 418              holdtime, (ds_tlv) ? " (dual stack TLV present)" : "");
 419
 420         if (nbr && nbr->state == NBR_STA_PRESENT && !nbr_pending_idtimer(nbr) &&
 421             nbr_session_active_role(nbr) && !nbr_pending_connect(nbr))
 422                 nbr_establish_connection(nbr);
 423 }
 424
 425 static int
 426 gen_hello_prms_tlv(struct ibuf *buf, uint16_t holdtime, uint16_t flags)
 427 {
 428         struct hello_prms_tlv   parms;
 429
 430         memset(&parms, 0, sizeof(parms));
 431         parms.type = htons(TLV_TYPE_COMMONHELLO);
 432         parms.length = htons(sizeof(parms.holdtime) + sizeof(parms.flags));
 433         parms.holdtime = htons(holdtime);
 434         parms.flags = htons(flags);
 435
 436         return (ibuf_add(buf, &parms, sizeof(parms)));
 437 }
 438
 439 static int
 440 gen_opt4_hello_prms_tlv(struct ibuf *buf, uint16_t type, uint32_t value)
 441 {
 442         struct hello_prms_opt4_tlv      parms;
 443
 444         memset(&parms, 0, sizeof(parms));
 445         parms.type = htons(type);
 446         parms.length = htons(sizeof(parms.value));
 447         parms.value = value;
 448
 449         return (ibuf_add(buf, &parms, sizeof(parms)));
 450 }
 451
 452 static int
 453 gen_opt16_hello_prms_tlv(struct ibuf *buf, uint16_t type, uint8_t *value)
 454 {
 455         struct hello_prms_opt16_tlv     parms;
 456
 457         memset(&parms, 0, sizeof(parms));
 458         parms.type = htons(type);
 459         parms.length = htons(sizeof(parms.value));
 460         memcpy(&parms.value, value, sizeof(parms.value));
 461
 462         return (ibuf_add(buf, &parms, sizeof(parms)));
 463 }
 464
 465 static int
 466 gen_ds_hello_prms_tlv(struct ibuf *buf, uint32_t value)
 467 {
 468         if (leconf->flags & F_LDPD_DS_CISCO_INTEROP)
 469                 value = htonl(value);
 470         else
 471                 value = htonl(value << 28);
 472
 473         return (gen_opt4_hello_prms_tlv(buf, TLV_TYPE_DUALSTACK, value));
 474 }
 475
 476 static int
 477 tlv_decode_hello_prms(char *buf, uint16_t len, uint16_t *holdtime,
 478     uint16_t *flags)
 479 {
 480         struct hello_prms_tlv   tlv;
 481
 482         if (len < sizeof(tlv))
 483                 return (-1);
 484         memcpy(&tlv, buf, sizeof(tlv));
 485
 486         if (tlv.type != htons(TLV_TYPE_COMMONHELLO))
 487                 return (-1);
 488         if (ntohs(tlv.length) != sizeof(tlv) - TLV_HDR_SIZE)
 489                 return (-1);
 490
 491         *holdtime = ntohs(tlv.holdtime);
 492         *flags = ntohs(tlv.flags);
 493
 494         return (sizeof(tlv));
 495 }
 496
 497 static int
 498 tlv_decode_opt_hello_prms(char *buf, uint16_t len, int *tlvs_rcvd, int af,
 499     union ldpd_addr *addr, uint32_t *conf_number, uint16_t *trans_pref)
 500 {
 501         struct tlv      tlv;
 502         uint16_t        tlv_len;
 503         int             total = 0;
 504
 505         *tlvs_rcvd = 0;
 506         memset(addr, 0, sizeof(*addr));
 507         *conf_number = 0;
 508         *trans_pref = 0;
 509
 510         /*
 511          * RFC 7552 - Section 6.1:
 512          * "An LSR SHOULD accept the Hello message that contains both IPv4 and
 513          * IPv6 Transport Address optional objects but MUST use only the
 514          * transport address whose address family is the same as that of the
 515          * IP packet carrying the Hello message.  An LSR SHOULD accept only
 516          * the first Transport Address optional object for a given address
 517          * family in the received Hello message and ignore the rest if the
 518          * LSR receives more than one Transport Address optional object for a
 519          * given address family".
 520          */
 521         while (len >= sizeof(tlv)) {
 522                 memcpy(&tlv, buf, TLV_HDR_SIZE);
 523                 tlv_len = ntohs(tlv.length);
 524                 if (tlv_len + TLV_HDR_SIZE > len)
 525                         return (-1);
 526                 buf += TLV_HDR_SIZE;
 527                 len -= TLV_HDR_SIZE;
 528                 total += TLV_HDR_SIZE;
 529
 530                 switch (ntohs(tlv.type)) {
 531                 case TLV_TYPE_IPV4TRANSADDR:
 532                         if (tlv_len != sizeof(addr->v4))
 533                                 return (-1);
 534                         if (af != AF_INET)
 535                                 return (-1);
 536                         if (*tlvs_rcvd & F_HELLO_TLV_RCVD_ADDR)
 537                                 break;
 538                         memcpy(&addr->v4, buf, sizeof(addr->v4));
 539                         *tlvs_rcvd |= F_HELLO_TLV_RCVD_ADDR;
 540                         break;
 541                 case TLV_TYPE_IPV6TRANSADDR:
 542                         if (tlv_len != sizeof(addr->v6))
 543                                 return (-1);
 544                         if (af != AF_INET6)
 545                                 return (-1);
 546                         if (*tlvs_rcvd & F_HELLO_TLV_RCVD_ADDR)
 547                                 break;
 548                         memcpy(&addr->v6, buf, sizeof(addr->v6));
 549                         *tlvs_rcvd |= F_HELLO_TLV_RCVD_ADDR;
 550                         break;
 551                 case TLV_TYPE_CONFIG:
 552                         if (tlv_len != sizeof(uint32_t))
 553                                 return (-1);
 554                         memcpy(conf_number, buf, sizeof(uint32_t));
 555                         *tlvs_rcvd |= F_HELLO_TLV_RCVD_CONF;
 556                         break;
 557                 case TLV_TYPE_DUALSTACK:
 558                         if (tlv_len != sizeof(uint32_t))
 559                                 return (-1);
 560                         /*
 561                          * RFC 7552 - Section 6.1:
 562                          * "A Single-stack LSR does not need to use the
 563                          * Dual-Stack capability in Hello messages and SHOULD
 564                          * ignore this capability if received".
 565                          */
 566                         if (!ldp_is_dual_stack(leconf))
 567                                 break;
 568                         /* Shame on you, Cisco! */
 569                         if (leconf->flags & F_LDPD_DS_CISCO_INTEROP) {
 570                                 memcpy(trans_pref, buf + sizeof(uint16_t),
 571                                     sizeof(uint16_t));
 572                                 *trans_pref = ntohs(*trans_pref);
 573                         } else {
 574                                 memcpy(trans_pref, buf , sizeof(uint16_t));
 575                                 *trans_pref = ntohs(*trans_pref) >> 12;
 576                         }
 577                         *tlvs_rcvd |= F_HELLO_TLV_RCVD_DS;
 578                         break;
 579                 default:
 580                         /* if unknown flag set, ignore TLV */
 581                         if (!(ntohs(tlv.type) & UNKNOWN_FLAG))
 582                                 return (-1);
 583                         break;
 584                 }
 585                 buf += tlv_len;
 586                 len -= tlv_len;
 587                 total += tlv_len;
 588         }
 589
 590         return (total);
 591 }