bfdd/bfd_packet.c

   1 /*********************************************************************
   2  * Copyright 2017 Cumulus Networks, Inc.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License as published by the Free
   6  * Software Foundation; either version 2 of the License, or (at your option)
   7  * any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; see the file COPYING; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  17  *
  18  * bfd_packet.c: implements the BFD protocol packet handling.
  19  *
  20  * Authors
  21  * -------
  22  * Shrijeet Mukherjee [shm@cumulusnetworks.com]
  23  * Kanna Rajagopal [kanna@cumulusnetworks.com]
  24  * Radhika Mahankali [Radhika@cumulusnetworks.com]
  25  */
  26
  27 #include <zebra.h>
  28
  29 #ifdef BFD_LINUX
  30 #include <linux/if_packet.h>
  31 #endif /* BFD_LINUX */
  32
  33 #include <netinet/if_ether.h>
  34 #include <netinet/udp.h>
  35
  36 #include "lib/sockopt.h"
  37
  38 #include "bfd.h"
  39
  40
  41 /*
  42  * Prototypes
  43  */
  44 static int ptm_bfd_process_echo_pkt(int s);
  45 int _ptm_bfd_send(struct bfd_session *bs, uint16_t *port, const void *data,
  46                   size_t datalen);
  47
  48 static void bfd_sd_reschedule(int sd);
  49 ssize_t bfd_recv_ipv4(int sd, uint8_t *msgbuf, size_t msgbuflen, uint8_t *ttl,
  50                       ifindex_t *ifindex, struct sockaddr_any *local,
  51                       struct sockaddr_any *peer);
  52 ssize_t bfd_recv_ipv6(int sd, uint8_t *msgbuf, size_t msgbuflen, uint8_t *ttl,
  53                       ifindex_t *ifindex, struct sockaddr_any *local,
  54                       struct sockaddr_any *peer);
  55 int bp_udp_send(int sd, uint8_t ttl, uint8_t *data, size_t datalen,
  56                 struct sockaddr *to, socklen_t tolen);
  57 int bp_bfd_echo_in(int sd, uint8_t *ttl, uint32_t *my_discr);
  58
  59 /* socket related prototypes */
  60 static void bp_set_ipopts(int sd);
  61 static void bp_bind_ip(int sd, uint16_t port);
  62 static void bp_set_ipv6opts(int sd);
  63 static void bp_bind_ipv6(int sd, uint16_t port);
  64
  65
  66 /*
  67  * Functions
  68  */
  69 int _ptm_bfd_send(struct bfd_session *bs, uint16_t *port, const void *data,
  70                   size_t datalen)
  71 {
  72         struct sockaddr *sa;
  73         struct sockaddr_in sin;
  74         struct sockaddr_in6 sin6;
  75         socklen_t slen;
  76         ssize_t rv;
  77         int sd = -1;
  78
  79         if (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_IPV6)) {
  80                 memset(&sin6, 0, sizeof(sin6));
  81                 sin6.sin6_family = AF_INET6;
  82                 sin6.sin6_addr = bs->shop.peer.sa_sin6.sin6_addr;
  83                 sin6.sin6_port =
  84                         (port) ? *port
  85                                : (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_MH))
  86                                          ? htons(BFD_DEF_MHOP_DEST_PORT)
  87                                          : htons(BFD_DEFDESTPORT);
  88
  89                 sd = bs->sock;
  90                 sa = (struct sockaddr *)&sin6;
  91                 slen = sizeof(sin6);
  92         } else {
  93                 memset(&sin, 0, sizeof(sin));
  94                 sin.sin_family = AF_INET;
  95                 sin.sin_addr = bs->shop.peer.sa_sin.sin_addr;
  96                 sin.sin_port =
  97                         (port) ? *port
  98                                : (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_MH))
  99                                          ? htons(BFD_DEF_MHOP_DEST_PORT)
 100                                          : htons(BFD_DEFDESTPORT);
 101
 102                 sd = bs->sock;
 103                 sa = (struct sockaddr *)&sin;
 104                 slen = sizeof(sin);
 105         }
 106
 107 #ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
 108         sa->sa_len = slen;
 109 #endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
 110         rv = sendto(sd, data, datalen, 0, sa, slen);
 111         if (rv <= 0) {
 112                 log_debug("packet-send: send failure: %s", strerror(errno));
 113                 return -1;
 114         }
 115         if (rv < (ssize_t)datalen)
 116                 log_debug("packet-send: send partial", strerror(errno));
 117
 118         return 0;
 119 }
 120
 121 void ptm_bfd_echo_snd(struct bfd_session *bfd)
 122 {
 123         struct sockaddr_any *sa;
 124         socklen_t salen;
 125         int sd;
 126         struct bfd_echo_pkt bep;
 127         struct sockaddr_in sin;
 128         struct sockaddr_in6 sin6;
 129
 130         if (!BFD_CHECK_FLAG(bfd->flags, BFD_SESS_FLAG_ECHO_ACTIVE))
 131                 BFD_SET_FLAG(bfd->flags, BFD_SESS_FLAG_ECHO_ACTIVE);
 132
 133         memset(&bep, 0, sizeof(bep));
 134         bep.ver = BFD_ECHO_VERSION;
 135         bep.len = BFD_ECHO_PKT_LEN;
 136         bep.my_discr = htonl(bfd->discrs.my_discr);
 137
 138         sa = BFD_CHECK_FLAG(bfd->flags, BFD_SESS_FLAG_MH) ? &bfd->mhop.peer
 139                                                           : &bfd->shop.peer;
 140         if (BFD_CHECK_FLAG(bfd->flags, BFD_SESS_FLAG_IPV6)) {
 141                 sd = bglobal.bg_echov6;
 142                 sin6 = sa->sa_sin6;
 143                 sin6.sin6_port = htons(BFD_DEF_ECHO_PORT);
 144 #ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
 145                 sin6.sin6_len = sizeof(sin6);
 146 #endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
 147
 148                 sa = (struct sockaddr_any *)&sin6;
 149                 salen = sizeof(sin6);
 150         } else {
 151                 sd = bglobal.bg_echo;
 152                 sin = sa->sa_sin;
 153                 sin.sin_port = htons(BFD_DEF_ECHO_PORT);
 154 #ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
 155                 sin.sin_len = sizeof(sin);
 156 #endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
 157
 158                 sa = (struct sockaddr_any *)&sin;
 159                 salen = sizeof(sin);
 160         }
 161         if (bp_udp_send(sd, BFD_TTL_VAL, (uint8_t *)&bep, sizeof(bep),
 162                         (struct sockaddr *)sa, salen)
 163             == -1)
 164                 return;
 165
 166         bfd->stats.tx_echo_pkt++;
 167 }
 168
 169 static int ptm_bfd_process_echo_pkt(int s)
 170 {
 171         struct bfd_session *bfd;
 172         uint32_t my_discr = 0;
 173         uint8_t ttl = 0;
 174
 175         /* Receive and parse echo packet. */
 176         if (bp_bfd_echo_in(s, &ttl, &my_discr) == -1)
 177                 return 0;
 178
 179         /* Your discriminator not zero - use it to find session */
 180         bfd = bfd_id_lookup(my_discr);
 181         if (bfd == NULL) {
 182                 log_debug("echo-packet: no matching session (id:%u)", my_discr);
 183                 return -1;
 184         }
 185
 186         if (!BFD_CHECK_FLAG(bfd->flags, BFD_SESS_FLAG_ECHO_ACTIVE)) {
 187                 log_debug("echo-packet: echo disabled [%s] (id:%u)",
 188                           bs_to_string(bfd), my_discr);
 189                 return -1;
 190         }
 191
 192         bfd->stats.rx_echo_pkt++;
 193
 194         /* Compute detect time */
 195         bfd->echo_detect_TO = bfd->remote_detect_mult * bfd->echo_xmt_TO;
 196
 197         /* Update echo receive timeout. */
 198         if (bfd->echo_detect_TO > 0)
 199                 bfd_echo_recvtimer_update(bfd);
 200
 201         return 0;
 202 }
 203
 204 void ptm_bfd_snd(struct bfd_session *bfd, int fbit)
 205 {
 206         struct bfd_pkt cp;
 207
 208         /* Set fields according to section 6.5.7 */
 209         cp.diag = bfd->local_diag;
 210         BFD_SETVER(cp.diag, BFD_VERSION);
 211         cp.flags = 0;
 212         BFD_SETSTATE(cp.flags, bfd->ses_state);
 213         BFD_SETDEMANDBIT(cp.flags, BFD_DEF_DEMAND);
 214
 215         /*
 216          * Polling and Final can't be set at the same time.
 217          *
 218          * RFC 5880, Section 6.5.
 219          */
 220         BFD_SETFBIT(cp.flags, fbit);
 221         if (fbit == 0)
 222                 BFD_SETPBIT(cp.flags, bfd->polling);
 223
 224         cp.detect_mult = bfd->detect_mult;
 225         cp.len = BFD_PKT_LEN;
 226         cp.discrs.my_discr = htonl(bfd->discrs.my_discr);
 227         cp.discrs.remote_discr = htonl(bfd->discrs.remote_discr);
 228         if (bfd->polling) {
 229                 cp.timers.desired_min_tx =
 230                         htonl(bfd->timers.desired_min_tx);
 231                 cp.timers.required_min_rx =
 232                         htonl(bfd->timers.required_min_rx);
 233         } else {
 234                 /*
 235                  * We can only announce current setting on poll, this
 236                  * avoids timing mismatch with our peer and give it
 237                  * the oportunity to learn. See `bs_final_handler` for
 238                  * more information.
 239                  */
 240                 cp.timers.desired_min_tx =
 241                         htonl(bfd->cur_timers.desired_min_tx);
 242                 cp.timers.required_min_rx =
 243                         htonl(bfd->cur_timers.required_min_rx);
 244         }
 245         cp.timers.required_min_echo = htonl(bfd->timers.required_min_echo);
 246
 247         if (_ptm_bfd_send(bfd, NULL, &cp, BFD_PKT_LEN) != 0)
 248                 return;
 249
 250         bfd->stats.tx_ctrl_pkt++;
 251 }
 252
 253 ssize_t bfd_recv_ipv4(int sd, uint8_t *msgbuf, size_t msgbuflen, uint8_t *ttl,
 254                       ifindex_t *ifindex, struct sockaddr_any *local,
 255                       struct sockaddr_any *peer)
 256 {
 257         struct cmsghdr *cm;
 258         ssize_t mlen;
 259         struct sockaddr_in msgaddr;
 260         struct msghdr msghdr;
 261         struct iovec iov[1];
 262         uint8_t cmsgbuf[255];
 263
 264         /* Prepare the recvmsg params. */
 265         iov[0].iov_base = msgbuf;
 266         iov[0].iov_len = msgbuflen;
 267
 268         memset(&msghdr, 0, sizeof(msghdr));
 269         msghdr.msg_name = &msgaddr;
 270         msghdr.msg_namelen = sizeof(msgaddr);
 271         msghdr.msg_iov = iov;
 272         msghdr.msg_iovlen = 1;
 273         msghdr.msg_control = cmsgbuf;
 274         msghdr.msg_controllen = sizeof(cmsgbuf);
 275
 276         mlen = recvmsg(sd, &msghdr, MSG_DONTWAIT);
 277         if (mlen == -1) {
 278                 if (errno != EAGAIN)
 279                         log_error("ipv4-recv: recv failed: %s",
 280                                   strerror(errno));
 281
 282                 return -1;
 283         }
 284
 285         /* Get source address */
 286         peer->sa_sin = *((struct sockaddr_in *)(msghdr.msg_name));
 287
 288         /* Get and check TTL */
 289         for (cm = CMSG_FIRSTHDR(&msghdr); cm != NULL;
 290              cm = CMSG_NXTHDR(&msghdr, cm)) {
 291                 if (cm->cmsg_level != IPPROTO_IP)
 292                         continue;
 293
 294                 switch (cm->cmsg_type) {
 295 #ifdef BFD_LINUX
 296                 case IP_TTL: {
 297                         uint32_t ttlval;
 298
 299                         memcpy(&ttlval, CMSG_DATA(cm), sizeof(ttlval));
 300                         if (ttlval > 255) {
 301                                 log_debug("ipv4-recv: invalid TTL: %u", ttlval);
 302                                 return -1;
 303                         }
 304                         *ttl = ttlval;
 305                         break;
 306                 }
 307
 308                 case IP_PKTINFO: {
 309                         struct in_pktinfo *pi =
 310                                 (struct in_pktinfo *)CMSG_DATA(cm);
 311
 312                         if (pi == NULL)
 313                                 break;
 314
 315                         local->sa_sin.sin_family = AF_INET;
 316                         local->sa_sin.sin_addr = pi->ipi_addr;
 317 #ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
 318                         local->sa_sin.sin_len = sizeof(local->sa_sin);
 319 #endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
 320
 321                         *ifindex = pi->ipi_ifindex;
 322                         break;
 323                 }
 324 #endif /* BFD_LINUX */
 325 #ifdef BFD_BSD
 326                 case IP_RECVTTL: {
 327                         memcpy(ttl, CMSG_DATA(cm), sizeof(*ttl));
 328                         break;
 329                 }
 330
 331                 case IP_RECVDSTADDR: {
 332                         struct in_addr ia;
 333
 334                         memcpy(&ia, CMSG_DATA(cm), sizeof(ia));
 335                         local->sa_sin.sin_family = AF_INET;
 336                         local->sa_sin.sin_addr = ia;
 337 #ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
 338                         local->sa_sin.sin_len = sizeof(local->sa_sin);
 339 #endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
 340                         break;
 341                 }
 342 #endif /* BFD_BSD */
 343
 344                 default:
 345                         /*
 346                          * On *BSDs we expect to land here when skipping
 347                          * the IP_RECVIF header. It will be handled by
 348                          * getsockopt_ifindex() below.
 349                          */
 350                         /* NOTHING */
 351                         break;
 352                 }
 353         }
 354
 355         /* OS agnostic way of getting interface name. */
 356         if (*ifindex == IFINDEX_INTERNAL)
 357                 *ifindex = getsockopt_ifindex(AF_INET, &msghdr);
 358
 359         return mlen;
 360 }
 361
 362 ssize_t bfd_recv_ipv6(int sd, uint8_t *msgbuf, size_t msgbuflen, uint8_t *ttl,
 363                       ifindex_t *ifindex, struct sockaddr_any *local,
 364                       struct sockaddr_any *peer)
 365 {
 366         struct cmsghdr *cm;
 367         struct in6_pktinfo *pi6 = NULL;
 368         ssize_t mlen;
 369         uint32_t ttlval;
 370         struct sockaddr_in6 msgaddr6;
 371         struct msghdr msghdr6;
 372         struct iovec iov[1];
 373         uint8_t cmsgbuf6[255];
 374
 375         /* Prepare the recvmsg params. */
 376         iov[0].iov_base = msgbuf;
 377         iov[0].iov_len = msgbuflen;
 378
 379         memset(&msghdr6, 0, sizeof(msghdr6));
 380         msghdr6.msg_name = &msgaddr6;
 381         msghdr6.msg_namelen = sizeof(msgaddr6);
 382         msghdr6.msg_iov = iov;
 383         msghdr6.msg_iovlen = 1;
 384         msghdr6.msg_control = cmsgbuf6;
 385         msghdr6.msg_controllen = sizeof(cmsgbuf6);
 386
 387         mlen = recvmsg(sd, &msghdr6, MSG_DONTWAIT);
 388         if (mlen == -1) {
 389                 if (errno != EAGAIN)
 390                         log_error("ipv6-recv: recv failed: %s",
 391                                   strerror(errno));
 392
 393                 return -1;
 394         }
 395
 396         /* Get source address */
 397         peer->sa_sin6 = *((struct sockaddr_in6 *)(msghdr6.msg_name));
 398
 399         /* Get and check TTL */
 400         for (cm = CMSG_FIRSTHDR(&msghdr6); cm != NULL;
 401              cm = CMSG_NXTHDR(&msghdr6, cm)) {
 402                 if (cm->cmsg_level != IPPROTO_IPV6)
 403                         continue;
 404
 405                 if (cm->cmsg_type == IPV6_HOPLIMIT) {
 406                         memcpy(&ttlval, CMSG_DATA(cm), sizeof(ttlval));
 407                         if (ttlval > 255) {
 408                                 log_debug("ipv6-recv: invalid TTL: %u", ttlval);
 409                                 return -1;
 410                         }
 411
 412                         *ttl = ttlval;
 413                 } else if (cm->cmsg_type == IPV6_PKTINFO) {
 414                         pi6 = (struct in6_pktinfo *)CMSG_DATA(cm);
 415                         if (pi6) {
 416                                 local->sa_sin6.sin6_family = AF_INET6;
 417                                 local->sa_sin6.sin6_addr = pi6->ipi6_addr;
 418 #ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
 419                                 local->sa_sin6.sin6_len = sizeof(local->sa_sin6);
 420 #endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
 421
 422                                 *ifindex = pi6->ipi6_ifindex;
 423                         }
 424                 }
 425         }
 426
 427         /* Set scope ID for link local addresses. */
 428         if (IN6_IS_ADDR_LINKLOCAL(&peer->sa_sin6.sin6_addr))
 429                 peer->sa_sin6.sin6_scope_id = *ifindex;
 430         if (IN6_IS_ADDR_LINKLOCAL(&local->sa_sin6.sin6_addr))
 431                 local->sa_sin6.sin6_scope_id = *ifindex;
 432
 433         return mlen;
 434 }
 435
 436 static void bfd_sd_reschedule(int sd)
 437 {
 438         if (sd == bglobal.bg_shop) {
 439                 THREAD_OFF(bglobal.bg_ev[0]);
 440                 thread_add_read(master, bfd_recv_cb, NULL, bglobal.bg_shop,
 441                                 &bglobal.bg_ev[0]);
 442         } else if (sd == bglobal.bg_mhop) {
 443                 THREAD_OFF(bglobal.bg_ev[1]);
 444                 thread_add_read(master, bfd_recv_cb, NULL, bglobal.bg_mhop,
 445                                 &bglobal.bg_ev[1]);
 446         } else if (sd == bglobal.bg_shop6) {
 447                 THREAD_OFF(bglobal.bg_ev[2]);
 448                 thread_add_read(master, bfd_recv_cb, NULL, bglobal.bg_shop6,
 449                                 &bglobal.bg_ev[2]);
 450         } else if (sd == bglobal.bg_mhop6) {
 451                 THREAD_OFF(bglobal.bg_ev[3]);
 452                 thread_add_read(master, bfd_recv_cb, NULL, bglobal.bg_mhop6,
 453                                 &bglobal.bg_ev[3]);
 454         } else if (sd == bglobal.bg_echo) {
 455                 THREAD_OFF(bglobal.bg_ev[4]);
 456                 thread_add_read(master, bfd_recv_cb, NULL, bglobal.bg_echo,
 457                                 &bglobal.bg_ev[4]);
 458         } else if (sd == bglobal.bg_echov6) {
 459                 THREAD_OFF(bglobal.bg_ev[5]);
 460                 thread_add_read(master, bfd_recv_cb, NULL, bglobal.bg_echov6,
 461                                 &bglobal.bg_ev[5]);
 462         }
 463 }
 464
 465 static void cp_debug(bool mhop, struct sockaddr_any *peer,
 466                      struct sockaddr_any *local, ifindex_t ifindex,
 467                      vrf_id_t vrfid, const char *fmt, ...)
 468 {
 469         char buf[512], peerstr[128], localstr[128], portstr[64], vrfstr[64];
 470         va_list vl;
 471
 472         if (peer->sa_sin.sin_family)
 473                 snprintf(peerstr, sizeof(peerstr), " peer:%s", satostr(peer));
 474         else
 475                 peerstr[0] = 0;
 476
 477         if (local->sa_sin.sin_family)
 478                 snprintf(localstr, sizeof(localstr), " local:%s",
 479                          satostr(local));
 480         else
 481                 localstr[0] = 0;
 482
 483         if (ifindex != IFINDEX_INTERNAL)
 484                 snprintf(portstr, sizeof(portstr), " port:%u", ifindex);
 485         else
 486                 portstr[0] = 0;
 487
 488         if (vrfid != VRF_DEFAULT)
 489                 snprintf(vrfstr, sizeof(vrfstr), " vrf:%u", vrfid);
 490         else
 491                 vrfstr[0] = 0;
 492
 493         va_start(vl, fmt);
 494         vsnprintf(buf, sizeof(buf), fmt, vl);
 495         va_end(vl);
 496
 497         log_debug("control-packet: %s [mhop:%s%s%s%s%s]", buf,
 498                   mhop ? "yes" : "no", peerstr, localstr, portstr, vrfstr);
 499 }
 500
 501 int bfd_recv_cb(struct thread *t)
 502 {
 503         int sd = THREAD_FD(t);
 504         struct bfd_session *bfd;
 505         struct bfd_pkt *cp;
 506         bool is_mhop;
 507         ssize_t mlen = 0;
 508         uint8_t ttl = 0;
 509         vrf_id_t vrfid = VRF_DEFAULT;
 510         ifindex_t ifindex = IFINDEX_INTERNAL;
 511         struct sockaddr_any local, peer;
 512         uint8_t msgbuf[1516];
 513
 514         /* Schedule next read. */
 515         bfd_sd_reschedule(sd);
 516
 517         /* Handle echo packets. */
 518         if (sd == bglobal.bg_echo || sd == bglobal.bg_echov6) {
 519                 ptm_bfd_process_echo_pkt(sd);
 520                 return 0;
 521         }
 522
 523         /* Sanitize input/output. */
 524         memset(&local, 0, sizeof(local));
 525         memset(&peer, 0, sizeof(peer));
 526
 527         /* Handle control packets. */
 528         is_mhop = false;
 529         if (sd == bglobal.bg_shop || sd == bglobal.bg_mhop) {
 530                 is_mhop = sd == bglobal.bg_mhop;
 531                 mlen = bfd_recv_ipv4(sd, msgbuf, sizeof(msgbuf), &ttl, &ifindex,
 532                                      &local, &peer);
 533         } else if (sd == bglobal.bg_shop6 || sd == bglobal.bg_mhop6) {
 534                 is_mhop = sd == bglobal.bg_mhop6;
 535                 mlen = bfd_recv_ipv6(sd, msgbuf, sizeof(msgbuf), &ttl, &ifindex,
 536                                      &local, &peer);
 537         }
 538
 539         /* Implement RFC 5880 6.8.6 */
 540         if (mlen < BFD_PKT_LEN) {
 541                 cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
 542                          "too small (%ld bytes)", mlen);
 543                 return 0;
 544         }
 545
 546         /* Validate packet TTL. */
 547         if ((!is_mhop) && (ttl != BFD_TTL_VAL)) {
 548                 cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
 549                          "invalid TTL: %d expected %d", ttl, BFD_TTL_VAL);
 550                 return 0;
 551         }
 552
 553         /*
 554          * Parse the control header for inconsistencies:
 555          * - Invalid version;
 556          * - Bad multiplier configuration;
 557          * - Short packets;
 558          * - Invalid discriminator;
 559          */
 560         cp = (struct bfd_pkt *)(msgbuf);
 561         if (BFD_GETVER(cp->diag) != BFD_VERSION) {
 562                 cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
 563                          "bad version %d", BFD_GETVER(cp->diag));
 564                 return 0;
 565         }
 566
 567         if (cp->detect_mult == 0) {
 568                 cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
 569                          "detect multiplier set to zero");
 570                 return 0;
 571         }
 572
 573         if ((cp->len < BFD_PKT_LEN) || (cp->len > mlen)) {
 574                 cp_debug(is_mhop, &peer, &local, ifindex, vrfid, "too small");
 575                 return 0;
 576         }
 577
 578         if (cp->discrs.my_discr == 0) {
 579                 cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
 580                          "'my discriminator' is zero");
 581                 return 0;
 582         }
 583
 584         /* Find the session that this packet belongs. */
 585         bfd = ptm_bfd_sess_find(cp, &peer, &local, ifindex, vrfid, is_mhop);
 586         if (bfd == NULL) {
 587                 cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
 588                          "no session found");
 589                 return 0;
 590         }
 591
 592         bfd->stats.rx_ctrl_pkt++;
 593
 594         /*
 595          * Multi hop: validate packet TTL.
 596          * Single hop: set local address that received the packet.
 597          */
 598         if (is_mhop) {
 599                 if ((BFD_TTL_VAL - bfd->mh_ttl) > BFD_TTL_VAL) {
 600                         cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
 601                                  "exceeded max hop count (expected %d, got %d)",
 602                                  bfd->mh_ttl, BFD_TTL_VAL);
 603                         return 0;
 604                 }
 605         } else if (bfd->local_ip.sa_sin.sin_family == AF_UNSPEC) {
 606                 bfd->local_ip = local;
 607         }
 608
 609         /*
 610          * If no interface was detected, save the interface where the
 611          * packet came in.
 612          */
 613         if (bfd->ifp == NULL)
 614                 bfd->ifp = if_lookup_by_index(ifindex, vrfid);
 615
 616         /* Log remote discriminator changes. */
 617         if ((bfd->discrs.remote_discr != 0)
 618             && (bfd->discrs.remote_discr != ntohl(cp->discrs.my_discr)))
 619                 cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
 620                          "remote discriminator mismatch (expected %u, got %u)",
 621                          bfd->discrs.remote_discr, ntohl(cp->discrs.my_discr));
 622
 623         bfd->discrs.remote_discr = ntohl(cp->discrs.my_discr);
 624
 625         /* Save remote diagnostics before state switch. */
 626         bfd->remote_diag = cp->diag & BFD_DIAGMASK;
 627
 628         /* Update remote timers settings. */
 629         bfd->remote_timers.desired_min_tx = ntohl(cp->timers.desired_min_tx);
 630         bfd->remote_timers.required_min_rx = ntohl(cp->timers.required_min_rx);
 631         bfd->remote_timers.required_min_echo =
 632                 ntohl(cp->timers.required_min_echo);
 633         bfd->remote_detect_mult = cp->detect_mult;
 634
 635         /* State switch from section 6.2. */
 636         bs_state_handler(bfd, BFD_GETSTATE(cp->flags));
 637
 638         /* RFC 5880, Section 6.5: handle POLL/FINAL negotiation sequence. */
 639         if (bfd->polling && BFD_GETFBIT(cp->flags)) {
 640                 /* Disable pooling. */
 641                 bfd->polling = 0;
 642
 643                 /* Handle poll finalization. */
 644                 bs_final_handler(bfd);
 645         } else {
 646                 /* Received a packet, lets update the receive timer. */
 647                 bfd_recvtimer_update(bfd);
 648         }
 649
 650         /* Handle echo timers changes. */
 651         bs_echo_timer_handler(bfd);
 652
 653         /*
 654          * We've received a packet with the POLL bit set, we must send
 655          * a control packet back with the FINAL bit set.
 656          *
 657          * RFC 5880, Section 6.5.
 658          */
 659         if (BFD_GETPBIT(cp->flags)) {
 660                 /* We are finalizing a poll negotiation. */
 661                 bs_final_handler(bfd);
 662
 663                 /* Send the control packet with the final bit immediately. */
 664                 ptm_bfd_snd(bfd, 1);
 665         }
 666
 667         return 0;
 668 }
 669
 670 /*
 671  * bp_bfd_echo_in: proccesses an BFD echo packet. On TTL == BFD_TTL_VAL
 672  * the packet is looped back or returns the my discriminator ID along
 673  * with the TTL.
 674  *
 675  * Returns -1 on error or loopback or 0 on success.
 676  */
 677 int bp_bfd_echo_in(int sd, uint8_t *ttl, uint32_t *my_discr)
 678 {
 679         struct bfd_echo_pkt *bep;
 680         ssize_t rlen;
 681         struct sockaddr_any local, peer;
 682         ifindex_t ifindex = IFINDEX_INTERNAL;
 683         vrf_id_t vrfid = VRF_DEFAULT;
 684         uint8_t msgbuf[1516];
 685
 686         if (sd == bglobal.bg_echo)
 687                 rlen = bfd_recv_ipv4(sd, msgbuf, sizeof(msgbuf), ttl, &ifindex,
 688                                      &local, &peer);
 689         else
 690                 rlen = bfd_recv_ipv6(sd, msgbuf, sizeof(msgbuf), ttl, &ifindex,
 691                                      &local, &peer);
 692
 693         /* Short packet, better not risk reading it. */
 694         if (rlen < (ssize_t)sizeof(*bep)) {
 695                 cp_debug(false, &peer, &local, ifindex, vrfid,
 696                          "small echo packet");
 697                 return -1;
 698         }
 699
 700         /* Test for loopback. */
 701         if (*ttl == BFD_TTL_VAL) {
 702                 bp_udp_send(sd, *ttl - 1, msgbuf, rlen,
 703                             (struct sockaddr *)&peer,
 704                             (sd == bglobal.bg_echo) ? sizeof(peer.sa_sin)
 705                                                     : sizeof(peer.sa_sin6));
 706                 return -1;
 707         }
 708
 709         /* Read my discriminator from BFD Echo packet. */
 710         bep = (struct bfd_echo_pkt *)msgbuf;
 711         *my_discr = ntohl(bep->my_discr);
 712         if (*my_discr == 0) {
 713                 cp_debug(false, &peer, &local, ifindex, vrfid,
 714                          "invalid echo packet discriminator (zero)");
 715                 return -1;
 716         }
 717
 718         return 0;
 719 }
 720
 721 int bp_udp_send(int sd, uint8_t ttl, uint8_t *data, size_t datalen,
 722                 struct sockaddr *to, socklen_t tolen)
 723 {
 724         struct cmsghdr *cmsg;
 725         ssize_t wlen;
 726         int ttlval = ttl;
 727         bool is_ipv6 = to->sa_family == AF_INET6;
 728         struct msghdr msg;
 729         struct iovec iov[1];
 730         uint8_t msgctl[255];
 731
 732         /* Prepare message data. */
 733         iov[0].iov_base = data;
 734         iov[0].iov_len = datalen;
 735
 736         memset(&msg, 0, sizeof(msg));
 737         memset(msgctl, 0, sizeof(msgctl));
 738         msg.msg_name = to;
 739         msg.msg_namelen = tolen;
 740         msg.msg_iov = iov;
 741         msg.msg_iovlen = 1;
 742
 743         /* Prepare the packet TTL information. */
 744         if (ttl > 0) {
 745                 /* Use ancillary data. */
 746                 msg.msg_control = msgctl;
 747                 msg.msg_controllen = CMSG_LEN(sizeof(ttlval));
 748
 749                 /* Configure the ancillary data. */
 750                 cmsg = CMSG_FIRSTHDR(&msg);
 751                 cmsg->cmsg_len = CMSG_LEN(sizeof(ttlval));
 752                 if (is_ipv6) {
 753                         cmsg->cmsg_level = IPPROTO_IPV6;
 754                         cmsg->cmsg_type = IPV6_HOPLIMIT;
 755                 } else {
 756 #if BFD_LINUX
 757                         cmsg->cmsg_level = IPPROTO_IP;
 758                         cmsg->cmsg_type = IP_TTL;
 759 #else
 760                         /* FreeBSD does not support TTL in ancillary data. */
 761                         msg.msg_control = NULL;
 762                         msg.msg_controllen = 0;
 763
 764                         bp_set_ttl(sd, ttl);
 765 #endif /* BFD_BSD */
 766                 }
 767                 memcpy(CMSG_DATA(cmsg), &ttlval, sizeof(ttlval));
 768         }
 769
 770         /* Send echo back. */
 771         wlen = sendmsg(sd, &msg, 0);
 772         if (wlen <= 0) {
 773                 log_debug("udp-send: loopback failure: (%d) %s", errno, strerror(errno));
 774                 return -1;
 775         } else if (wlen < (ssize_t)datalen) {
 776                 log_debug("udp-send: partial send: %ld expected %ld", wlen,
 777                           datalen);
 778                 return -1;
 779         }
 780
 781         return 0;
 782 }
 783
 784
 785 /*
 786  * Sockets creation.
 787  */
 788
 789
 790 /*
 791  * IPv4 sockets
 792  */
 793 int bp_set_ttl(int sd, uint8_t value)
 794 {
 795         int ttl = value;
 796
 797         if (setsockopt(sd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)) == -1) {
 798                 log_warning("set-ttl: setsockopt(IP_TTL, %d): %s", value,
 799                             strerror(errno));
 800                 return -1;
 801         }
 802
 803         return 0;
 804 }
 805
 806 int bp_set_tos(int sd, uint8_t value)
 807 {
 808         int tos = value;
 809
 810         if (setsockopt(sd, IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) == -1) {
 811                 log_warning("set-tos: setsockopt(IP_TOS, %d): %s", value,
 812                             strerror(errno));
 813                 return -1;
 814         }
 815
 816         return 0;
 817 }
 818
 819 static void bp_set_ipopts(int sd)
 820 {
 821         int rcvttl = BFD_RCV_TTL_VAL;
 822
 823         if (bp_set_ttl(sd, BFD_TTL_VAL) != 0)
 824                 log_fatal("set-ipopts: TTL configuration failed");
 825
 826         if (setsockopt(sd, IPPROTO_IP, IP_RECVTTL, &rcvttl, sizeof(rcvttl))
 827             == -1)
 828                 log_fatal("set-ipopts: setsockopt(IP_RECVTTL, %d): %s", rcvttl,
 829                           strerror(errno));
 830
 831 #ifdef BFD_LINUX
 832         int pktinfo = BFD_PKT_INFO_VAL;
 833
 834         /* Figure out address and interface to do the peer matching. */
 835         if (setsockopt(sd, IPPROTO_IP, IP_PKTINFO, &pktinfo, sizeof(pktinfo))
 836             == -1)
 837                 log_fatal("set-ipopts: setsockopt(IP_PKTINFO, %d): %s", pktinfo,
 838                           strerror(errno));
 839 #endif /* BFD_LINUX */
 840 #ifdef BFD_BSD
 841         int yes = 1;
 842
 843         /* Find out our address for peer matching. */
 844         if (setsockopt(sd, IPPROTO_IP, IP_RECVDSTADDR, &yes, sizeof(yes)) == -1)
 845                 log_fatal("set-ipopts: setsockopt(IP_RECVDSTADDR, %d): %s", yes,
 846                           strerror(errno));
 847
 848         /* Find out interface where the packet came in. */
 849         if (setsockopt_ifindex(AF_INET, sd, yes) == -1)
 850                 log_fatal("set-ipopts: setsockopt_ipv4_ifindex(%d): %s", yes,
 851                           strerror(errno));
 852 #endif /* BFD_BSD */
 853 }
 854
 855 static void bp_bind_ip(int sd, uint16_t port)
 856 {
 857         struct sockaddr_in sin;
 858
 859         memset(&sin, 0, sizeof(sin));
 860         sin.sin_family = AF_INET;
 861         sin.sin_addr.s_addr = htonl(INADDR_ANY);
 862         sin.sin_port = htons(port);
 863         if (bind(sd, (struct sockaddr *)&sin, sizeof(sin)) == -1)
 864                 log_fatal("bind-ip: bind: %s", strerror(errno));
 865 }
 866
 867 int bp_udp_shop(void)
 868 {
 869         int sd;
 870
 871         sd = socket(AF_INET, SOCK_DGRAM, PF_UNSPEC);
 872         if (sd == -1)
 873                 log_fatal("udp-shop: socket: %s", strerror(errno));
 874
 875         bp_set_ipopts(sd);
 876         bp_bind_ip(sd, BFD_DEFDESTPORT);
 877
 878         return sd;
 879 }
 880
 881 int bp_udp_mhop(void)
 882 {
 883         int sd;
 884
 885         sd = socket(AF_INET, SOCK_DGRAM, PF_UNSPEC);
 886         if (sd == -1)
 887                 log_fatal("udp-mhop: socket: %s", strerror(errno));
 888
 889         bp_set_ipopts(sd);
 890         bp_bind_ip(sd, BFD_DEF_MHOP_DEST_PORT);
 891
 892         return sd;
 893 }
 894
 895 int bp_peer_socket(const struct bfd_session *bs)
 896 {
 897         int sd, pcount;
 898         struct sockaddr_in sin;
 899         static int srcPort = BFD_SRCPORTINIT;
 900
 901         sd = socket(AF_INET, SOCK_DGRAM, PF_UNSPEC);
 902         if (sd == -1) {
 903                 log_error("ipv4-new: failed to create socket: %s",
 904                           strerror(errno));
 905                 return -1;
 906         }
 907
 908         /* Set TTL to 255 for all transmitted packets */
 909         if (bp_set_ttl(sd, BFD_TTL_VAL) != 0) {
 910                 close(sd);
 911                 return -1;
 912         }
 913
 914         /* Set TOS to CS6 for all transmitted packets */
 915         if (bp_set_tos(sd, BFD_TOS_VAL) != 0) {
 916                 close(sd);
 917                 return -1;
 918         }
 919
 920         if (bs->shop.ifindex != IFINDEX_INTERNAL) {
 921                 if (bp_bind_dev(sd, bs->ifp->name) != 0) {
 922                         close(sd);
 923                         return -1;
 924                 }
 925         } else if (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_MH) &&
 926                    bs->mhop.vrfid != VRF_DEFAULT) {
 927                 if (bp_bind_dev(sd, bs->vrf->name) != 0) {
 928                         close(sd);
 929                         return -1;
 930                 }
 931         }
 932
 933         /* Find an available source port in the proper range */
 934         sin = bs->local_ip.sa_sin;
 935         sin.sin_family = AF_INET;
 936 #ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
 937         sin.sin_len = sizeof(sin);
 938 #endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
 939         if (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_MH) == 0)
 940                 sin.sin_addr.s_addr = INADDR_ANY;
 941
 942         pcount = 0;
 943         do {
 944                 if ((++pcount) > (BFD_SRCPORTMAX - BFD_SRCPORTINIT)) {
 945                         /* Searched all ports, none available */
 946                         log_error("ipv4-new: failed to bind port: %s",
 947                                   strerror(errno));
 948                         close(sd);
 949                         return -1;
 950                 }
 951                 if (srcPort >= BFD_SRCPORTMAX)
 952                         srcPort = BFD_SRCPORTINIT;
 953                 sin.sin_port = htons(srcPort++);
 954         } while (bind(sd, (struct sockaddr *)&sin, sizeof(sin)) < 0);
 955
 956         return sd;
 957 }
 958
 959
 960 /*
 961  * IPv6 sockets
 962  */
 963
 964 int bp_peer_socketv6(const struct bfd_session *bs)
 965 {
 966         int sd, pcount;
 967         struct sockaddr_in6 sin6;
 968         static int srcPort = BFD_SRCPORTINIT;
 969
 970         sd = socket(AF_INET6, SOCK_DGRAM, PF_UNSPEC);
 971         if (sd == -1) {
 972                 log_error("ipv6-new: failed to create socket: %s",
 973                           strerror(errno));
 974                 return -1;
 975         }
 976
 977         /* Set TTL to 255 for all transmitted packets */
 978         if (bp_set_ttlv6(sd, BFD_TTL_VAL) != 0) {
 979                 close(sd);
 980                 return -1;
 981         }
 982
 983         /* Set TOS to CS6 for all transmitted packets */
 984         if (bp_set_tosv6(sd, BFD_TOS_VAL) != 0) {
 985                 close(sd);
 986                 return -1;
 987         }
 988
 989         /* Find an available source port in the proper range */
 990         sin6 = bs->local_ip.sa_sin6;
 991         sin6.sin6_family = AF_INET6;
 992 #ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
 993         sin6.sin6_len = sizeof(sin6);
 994 #endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
 995
 996         if (bs->shop.ifindex != IFINDEX_INTERNAL) {
 997                 if (bp_bind_dev(sd, bs->ifp->name) != 0) {
 998                         close(sd);
 999                         return -1;
1000                 }
1001         } else if (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_MH) &&
1002                    bs->mhop.vrfid != VRF_DEFAULT) {
1003                 if (bp_bind_dev(sd, bs->vrf->name) != 0) {
1004                         close(sd);
1005                         return -1;
1006                 }
1007         }
1008
1009         pcount = 0;
1010         do {
1011                 if ((++pcount) > (BFD_SRCPORTMAX - BFD_SRCPORTINIT)) {
1012                         /* Searched all ports, none available */
1013                         log_error("ipv6-new: failed to bind port: %s",
1014                                   strerror(errno));
1015                         close(sd);
1016                         return -1;
1017                 }
1018                 if (srcPort >= BFD_SRCPORTMAX)
1019                         srcPort = BFD_SRCPORTINIT;
1020                 sin6.sin6_port = htons(srcPort++);
1021         } while (bind(sd, (struct sockaddr *)&sin6, sizeof(sin6)) < 0);
1022
1023         return sd;
1024 }
1025
1026 int bp_set_ttlv6(int sd, uint8_t value)
1027 {
1028         int ttl = value;
1029
1030         if (setsockopt(sd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl))
1031             == -1) {
1032                 log_warning("set-ttlv6: setsockopt(IPV6_UNICAST_HOPS, %d): %s",
1033                             value, strerror(errno));
1034                 return -1;
1035         }
1036
1037         return 0;
1038 }
1039
1040 int bp_set_tosv6(int sd, uint8_t value)
1041 {
1042         int tos = value;
1043
1044         if (setsockopt(sd, IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos))
1045             == -1) {
1046                 log_warning("set-tosv6: setsockopt(IPV6_TCLASS, %d): %s", value,
1047                             strerror(errno));
1048                 return -1;
1049         }
1050
1051         return 0;
1052 }
1053
1054 static void bp_set_ipv6opts(int sd)
1055 {
1056         int ipv6_pktinfo = BFD_IPV6_PKT_INFO_VAL;
1057         int ipv6_only = BFD_IPV6_ONLY_VAL;
1058
1059         if (bp_set_ttlv6(sd, BFD_TTL_VAL) == -1)
1060                 log_fatal("set-ipv6opts: setsockopt(IPV6_UNICAST_HOPS, %d): %s",
1061                           BFD_TTL_VAL, strerror(errno));
1062
1063         if (setsockopt_ipv6_hoplimit(sd, BFD_RCV_TTL_VAL) == -1)
1064                 log_fatal("set-ipv6opts: setsockopt(IPV6_HOPLIMIT, %d): %s",
1065                           BFD_RCV_TTL_VAL, strerror(errno));
1066
1067         if (setsockopt_ipv6_pktinfo(sd, ipv6_pktinfo) == -1)
1068                 log_fatal("set-ipv6opts: setsockopt(IPV6_PKTINFO, %d): %s",
1069                           ipv6_pktinfo, strerror(errno));
1070
1071         if (setsockopt(sd, IPPROTO_IPV6, IPV6_V6ONLY, &ipv6_only,
1072                        sizeof(ipv6_only))
1073             == -1)
1074                 log_fatal("set-ipv6opts: setsockopt(IPV6_V6ONLY, %d): %s",
1075                           ipv6_only, strerror(errno));
1076 }
1077
1078 static void bp_bind_ipv6(int sd, uint16_t port)
1079 {
1080         struct sockaddr_in6 sin6;
1081
1082         memset(&sin6, 0, sizeof(sin6));
1083         sin6.sin6_family = AF_INET6;
1084         sin6.sin6_addr = in6addr_any;
1085         sin6.sin6_port = htons(port);
1086 #ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
1087         sin6.sin6_len = sizeof(sin6);
1088 #endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
1089         if (bind(sd, (struct sockaddr *)&sin6, sizeof(sin6)) == -1)
1090                 log_fatal("bind-ipv6: bind: %s", strerror(errno));
1091 }
1092
1093 int bp_udp6_shop(void)
1094 {
1095         int sd;
1096
1097         sd = socket(AF_INET6, SOCK_DGRAM, PF_UNSPEC);
1098         if (sd == -1)
1099                 log_fatal("udp6-shop: socket: %s", strerror(errno));
1100
1101         bp_set_ipv6opts(sd);
1102         bp_bind_ipv6(sd, BFD_DEFDESTPORT);
1103
1104         return sd;
1105 }
1106
1107 int bp_udp6_mhop(void)
1108 {
1109         int sd;
1110
1111         sd = socket(AF_INET6, SOCK_DGRAM, PF_UNSPEC);
1112         if (sd == -1)
1113                 log_fatal("udp6-mhop: socket: %s", strerror(errno));
1114
1115         bp_set_ipv6opts(sd);
1116         bp_bind_ipv6(sd, BFD_DEF_MHOP_DEST_PORT);
1117
1118         return sd;
1119 }
1120
1121 int bp_echo_socket(void)
1122 {
1123         int s;
1124
1125         s = socket(AF_INET, SOCK_DGRAM, 0);
1126         if (s == -1)
1127                 log_fatal("echo-socket: socket: %s", strerror(errno));
1128
1129         bp_set_ipopts(s);
1130         bp_bind_ip(s, BFD_DEF_ECHO_PORT);
1131
1132         return s;
1133 }
1134
1135 int bp_echov6_socket(void)
1136 {
1137         int s;
1138
1139         s = socket(AF_INET6, SOCK_DGRAM, 0);
1140         if (s == -1)
1141                 log_fatal("echov6-socket: socket: %s", strerror(errno));
1142
1143         bp_set_ipv6opts(s);
1144         bp_bind_ipv6(s, BFD_DEF_ECHO_PORT);
1145
1146         return s;
1147 }