pimd/pim_igmp_mtrace.c

   1 /*
   2  * Multicast traceroute for FRRouting
   3  * Copyright (C) 2017  Mladen Sablic
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; see the file COPYING; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19
  20 /* based on draft-ietf-idmr-traceroute-ipm-07 */
  21
  22 #include <zebra.h>
  23
  24 #include "pimd.h"
  25 #include "pim_instance.h"
  26 #include "pim_util.h"
  27 #include "pim_sock.h"
  28 #include "pim_rp.h"
  29 #include "pim_oil.h"
  30 #include "pim_ifchannel.h"
  31 #include "pim_macro.h"
  32 #include "pim_igmp_mtrace.h"
  33
  34 static struct in_addr mtrace_primary_address(struct interface *ifp)
  35 {
  36         struct connected *ifc;
  37         struct listnode *node;
  38         struct in_addr any;
  39         struct pim_interface *pim_ifp;
  40
  41         if (ifp->info) {
  42                 pim_ifp = ifp->info;
  43                 return pim_ifp->primary_address;
  44         }
  45
  46         any.s_addr = INADDR_ANY;
  47
  48         for (ALL_LIST_ELEMENTS_RO(ifp->connected, node, ifc)) {
  49                 struct prefix *p = ifc->address;
  50
  51                 if (p->family != AF_INET)
  52                         continue;
  53
  54                 if (!CHECK_FLAG(ifc->flags, ZEBRA_IFA_SECONDARY))
  55                         return p->u.prefix4;
  56                 /* in case no primary found, return a secondary */
  57                 any = p->u.prefix4;
  58         }
  59         return any;
  60 }
  61
  62 static bool mtrace_fwd_info_weak(struct pim_instance *pim,
  63                                     struct igmp_mtrace *mtracep,
  64                                     struct igmp_mtrace_rsp *rspp,
  65                                     struct interface **ifpp)
  66 {
  67         struct pim_nexthop nexthop;
  68         struct interface *ifp_in;
  69         struct in_addr nh_addr;
  70
  71         nh_addr.s_addr = INADDR_ANY;
  72
  73         memset(&nexthop, 0, sizeof(nexthop));
  74
  75         if (!pim_nexthop_lookup(pim, &nexthop, mtracep->src_addr, 1)) {
  76                 if (PIM_DEBUG_MTRACE)
  77                         zlog_debug("mtrace not found neighbor");
  78                 return false;
  79         }
  80
  81         if (PIM_DEBUG_MTRACE)
  82                 zlog_debug("mtrace pim_nexthop_lookup OK");
  83
  84         if (PIM_DEBUG_MTRACE)
  85                 zlog_debug("mtrace next_hop=%pPAs", &nexthop.mrib_nexthop_addr);
  86
  87         nh_addr = nexthop.mrib_nexthop_addr;
  88
  89         ifp_in = nexthop.interface;
  90
  91         /* return interface for forwarding mtrace packets */
  92         *ifpp = ifp_in;
  93
  94         /* 6.2.2. 4. Fill in the Incoming Interface Address... */
  95         rspp->incoming = mtrace_primary_address(ifp_in);
  96         rspp->prev_hop = nh_addr;
  97         rspp->in_count = htonl(MTRACE_UNKNOWN_COUNT);
  98         rspp->total = htonl(MTRACE_UNKNOWN_COUNT);
  99         rspp->rtg_proto = MTRACE_RTG_PROTO_PIM;
 100         return true;
 101 }
 102
 103 static bool mtrace_fwd_info(struct pim_instance *pim,
 104                             struct igmp_mtrace *mtracep,
 105                             struct igmp_mtrace_rsp *rspp,
 106                             struct interface **ifpp)
 107 {
 108         pim_sgaddr sg;
 109         struct pim_upstream *up;
 110         struct interface *ifp_in;
 111         struct in_addr nh_addr;
 112         uint32_t total;
 113
 114         memset(&sg, 0, sizeof(sg));
 115         sg.src = mtracep->src_addr;
 116         sg.grp = mtracep->grp_addr;
 117
 118         up = pim_upstream_find(pim, &sg);
 119
 120         if (!up) {
 121                 sg.src = PIMADDR_ANY;
 122                 up = pim_upstream_find(pim, &sg);
 123         }
 124
 125         if (!up)
 126                 return false;
 127
 128         if (!up->rpf.source_nexthop.interface) {
 129                 if (PIM_DEBUG_TRACE)
 130                         zlog_debug("%s: up %s RPF is not present", __func__,
 131                                    up->sg_str);
 132                 return false;
 133         }
 134
 135         ifp_in = up->rpf.source_nexthop.interface;
 136         nh_addr = up->rpf.source_nexthop.mrib_nexthop_addr;
 137         total = htonl(MTRACE_UNKNOWN_COUNT);
 138
 139         if (PIM_DEBUG_MTRACE)
 140                 zlog_debug("fwd_info: upstream next hop=%pI4", &nh_addr);
 141
 142         if (up->channel_oil)
 143                 total = up->channel_oil->cc.pktcnt;
 144
 145         /* return interface for forwarding mtrace packets */
 146         *ifpp = ifp_in;
 147
 148         /* 6.2.2. 4. Fill in the Incoming Interface Address... */
 149         rspp->incoming = mtrace_primary_address(ifp_in);
 150         rspp->prev_hop = nh_addr;
 151         rspp->in_count = htonl(MTRACE_UNKNOWN_COUNT);
 152         rspp->total = total;
 153         rspp->rtg_proto = MTRACE_RTG_PROTO_PIM;
 154
 155         /* 6.2.2. 4. Fill in ... S, and Src Mask */
 156         if (!pim_addr_is_any(sg.src)) {
 157                 rspp->s = 1;
 158                 rspp->src_mask = MTRACE_SRC_MASK_SOURCE;
 159         } else {
 160                 rspp->s = 0;
 161                 rspp->src_mask = MTRACE_SRC_MASK_GROUP;
 162         }
 163
 164         return true;
 165 }
 166
 167 static void mtrace_rsp_set_fwd_code(struct igmp_mtrace_rsp *mtrace_rspp,
 168                                     enum mtrace_fwd_code fwd_code)
 169 {
 170         if (mtrace_rspp->fwd_code == MTRACE_FWD_CODE_NO_ERROR)
 171                 mtrace_rspp->fwd_code = fwd_code;
 172 }
 173
 174 static void mtrace_rsp_init(struct igmp_mtrace_rsp *mtrace_rspp)
 175 {
 176         mtrace_rspp->arrival = 0;
 177         mtrace_rspp->incoming.s_addr = INADDR_ANY;
 178         mtrace_rspp->outgoing.s_addr = INADDR_ANY;
 179         mtrace_rspp->prev_hop.s_addr = INADDR_ANY;
 180         mtrace_rspp->in_count = htonl(MTRACE_UNKNOWN_COUNT);
 181         mtrace_rspp->out_count = htonl(MTRACE_UNKNOWN_COUNT);
 182         mtrace_rspp->total = htonl(MTRACE_UNKNOWN_COUNT);
 183         mtrace_rspp->rtg_proto = 0;
 184         mtrace_rspp->fwd_ttl = 0;
 185         mtrace_rspp->mbz = 0;
 186         mtrace_rspp->s = 0;
 187         mtrace_rspp->src_mask = 0;
 188         mtrace_rspp->fwd_code = MTRACE_FWD_CODE_NO_ERROR;
 189 }
 190
 191 static void mtrace_rsp_debug(uint32_t qry_id, int rsp,
 192                              struct igmp_mtrace_rsp *mrspp)
 193 {
 194         struct in_addr incoming = mrspp->incoming;
 195         struct in_addr outgoing = mrspp->outgoing;
 196         struct in_addr prev_hop = mrspp->prev_hop;
 197
 198         zlog_debug(
 199                 "Rx mt(%d) qid=%ud arr=%x in=%pI4 out=%pI4 prev=%pI4 proto=%d fwd=%d",
 200                 rsp, ntohl(qry_id), mrspp->arrival, &incoming, &outgoing,
 201                 &prev_hop, mrspp->rtg_proto, mrspp->fwd_code);
 202 }
 203
 204 static void mtrace_debug(struct pim_interface *pim_ifp,
 205                          struct igmp_mtrace *mtracep, int mtrace_len)
 206 {
 207         struct in_addr ga, sa, da, ra;
 208
 209         ga = mtracep->grp_addr;
 210         sa = mtracep->src_addr;
 211         da = mtracep->dst_addr;
 212         ra = mtracep->rsp_addr;
 213
 214         zlog_debug(
 215                 "Rx mtrace packet incoming on %pI4: hops=%d type=%d size=%d, grp=%pI4, src=%pI4, dst=%pI4 rsp=%pI4 ttl=%d qid=%ud",
 216                 &pim_ifp->primary_address, mtracep->hops, mtracep->type,
 217                 mtrace_len, &ga, &sa, &da, &ra, mtracep->rsp_ttl,
 218                 ntohl(mtracep->qry_id));
 219         if (mtrace_len > (int)sizeof(struct igmp_mtrace)) {
 220
 221                 int i;
 222
 223                 int responses = mtrace_len - sizeof(struct igmp_mtrace);
 224
 225                 if ((responses % sizeof(struct igmp_mtrace_rsp)) != 0)
 226                         if (PIM_DEBUG_MTRACE)
 227                                 zlog_debug(
 228                                         "Mtrace response block of wrong length");
 229
 230                 responses = responses / sizeof(struct igmp_mtrace_rsp);
 231
 232                 for (i = 0; i < responses; i++)
 233                         mtrace_rsp_debug(mtracep->qry_id, i, &mtracep->rsp[i]);
 234         }
 235 }
 236
 237 /* 5.1 Query Arrival Time */
 238 static uint32_t query_arrival_time(void)
 239 {
 240         struct timeval tv;
 241         uint32_t qat;
 242
 243         if (gettimeofday(&tv, NULL) < 0) {
 244                 if (PIM_DEBUG_MTRACE)
 245                         zlog_debug("Query arrival time lookup failed: errno=%d: %s",
 246                                    errno, safe_strerror(errno));
 247                 return 0;
 248         }
 249         /* not sure second offset correct, as I get different value */
 250         qat = ((tv.tv_sec + 32384) << 16) + ((tv.tv_usec << 10) / 15625);
 251
 252         return qat;
 253 }
 254
 255 static int mtrace_send_packet(struct interface *ifp,
 256                               struct igmp_mtrace *mtracep,
 257                               size_t mtrace_buf_len, struct in_addr dst_addr,
 258                               struct in_addr group_addr)
 259 {
 260         struct sockaddr_in to;
 261         socklen_t tolen;
 262         ssize_t sent;
 263         int ret;
 264         int fd;
 265         uint8_t ttl;
 266
 267         memset(&to, 0, sizeof(to));
 268         to.sin_family = AF_INET;
 269         to.sin_addr = dst_addr;
 270         tolen = sizeof(to);
 271
 272         if (PIM_DEBUG_MTRACE) {
 273                 struct in_addr if_addr;
 274                 struct in_addr rsp_addr = mtracep->rsp_addr;
 275
 276                 if_addr = mtrace_primary_address(ifp);
 277                 zlog_debug("Sending mtrace packet to %pI4 on %pI4", &rsp_addr,
 278                            &if_addr);
 279         }
 280
 281         fd = pim_socket_raw(IPPROTO_IGMP);
 282
 283         if (fd < 0)
 284                 return -1;
 285
 286         ret = pim_socket_bind(fd, ifp);
 287
 288         if (ret < 0) {
 289                 ret = -1;
 290                 goto close_fd;
 291         }
 292
 293         if (IPV4_CLASS_DE(ntohl(dst_addr.s_addr))) {
 294                 if (IPV4_MC_LINKLOCAL(ntohl(dst_addr.s_addr))) {
 295                         ttl = 1;
 296                 } else {
 297                         if (mtracep->type == PIM_IGMP_MTRACE_RESPONSE)
 298                                 ttl = mtracep->rsp_ttl;
 299                         else
 300                                 ttl = 64;
 301                 }
 302                 ret = setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl,
 303                                  sizeof(ttl));
 304
 305                 if (ret < 0) {
 306                         if (PIM_DEBUG_MTRACE)
 307                                 zlog_debug("Failed to set socket multicast TTL");
 308                         ret = -1;
 309                         goto close_fd;
 310                 }
 311         }
 312
 313         sent = sendto(fd, (char *)mtracep, mtrace_buf_len, MSG_DONTWAIT,
 314                       (struct sockaddr *)&to, tolen);
 315
 316         if (sent != (ssize_t)mtrace_buf_len) {
 317                 char dst_str[INET_ADDRSTRLEN];
 318                 char group_str[INET_ADDRSTRLEN];
 319
 320                 pim_inet4_dump("<dst?>", dst_addr, dst_str, sizeof(dst_str));
 321                 pim_inet4_dump("<group?>", group_addr, group_str,
 322                                sizeof(group_str));
 323                 if (sent < 0) {
 324                         if (PIM_DEBUG_MTRACE)
 325                                 zlog_debug(
 326                                         "Send mtrace request failed for %s on%s: group=%s msg_size=%zd: errno=%d:  %s",
 327                                         dst_str, ifp->name, group_str,
 328                                         mtrace_buf_len, errno,
 329                                         safe_strerror(errno));
 330                 } else {
 331                         if (PIM_DEBUG_MTRACE)
 332                                 zlog_debug(
 333                                         "Send mtrace request failed for %s on %s: group=%s msg_size=%zd: sent=%zd",
 334                                         dst_str, ifp->name, group_str,
 335                                         mtrace_buf_len, sent);
 336                 }
 337                 ret = -1;
 338                 goto close_fd;
 339         }
 340         ret = 0;
 341 close_fd:
 342         close(fd);
 343         return ret;
 344 }
 345
 346 static int mtrace_un_forward_packet(struct pim_instance *pim, struct ip *ip_hdr,
 347                                     struct interface *interface)
 348 {
 349         struct pim_nexthop nexthop;
 350         struct sockaddr_in to;
 351         struct interface *if_out;
 352         socklen_t tolen;
 353         int ret;
 354         int fd;
 355         int sent;
 356         uint16_t checksum;
 357
 358         checksum = ip_hdr->ip_sum;
 359
 360         ip_hdr->ip_sum = 0;
 361
 362         if (checksum != in_cksum(ip_hdr, ip_hdr->ip_hl * 4))
 363                 return -1;
 364
 365         if (ip_hdr->ip_ttl-- <= 1)
 366                 return -1;
 367
 368         ip_hdr->ip_sum = in_cksum(ip_hdr, ip_hdr->ip_hl * 4);
 369
 370         fd = pim_socket_raw(IPPROTO_RAW);
 371
 372         if (fd < 0)
 373                 return -1;
 374
 375         pim_socket_ip_hdr(fd);
 376
 377         if (interface == NULL) {
 378                 memset(&nexthop, 0, sizeof(nexthop));
 379                 if (!pim_nexthop_lookup(pim, &nexthop, ip_hdr->ip_dst, 0)) {
 380                         close(fd);
 381                         if (PIM_DEBUG_MTRACE)
 382                                 zlog_debug(
 383                                         "Dropping mtrace packet, no route to destination");
 384                         return -1;
 385                 }
 386
 387                 if_out = nexthop.interface;
 388         } else {
 389                 if_out = interface;
 390         }
 391
 392         ret = pim_socket_bind(fd, if_out);
 393
 394         if (ret < 0) {
 395                 close(fd);
 396                 return -1;
 397         }
 398
 399         memset(&to, 0, sizeof(to));
 400         to.sin_family = AF_INET;
 401         to.sin_addr = ip_hdr->ip_dst;
 402         tolen = sizeof(to);
 403
 404         sent = sendto(fd, ip_hdr, ntohs(ip_hdr->ip_len), 0,
 405                       (struct sockaddr *)&to, tolen);
 406
 407         close(fd);
 408
 409         if (sent < 0) {
 410                 if (PIM_DEBUG_MTRACE)
 411                         zlog_debug(
 412                                 "Failed to forward mtrace packet: sendto errno=%d, %s",
 413                                 errno, safe_strerror(errno));
 414                 return -1;
 415         }
 416
 417         if (PIM_DEBUG_MTRACE) {
 418                 zlog_debug("Fwd mtrace packet len=%u to %pI4 ttl=%u",
 419                            ntohs(ip_hdr->ip_len), &ip_hdr->ip_dst,
 420                            ip_hdr->ip_ttl);
 421         }
 422
 423         return 0;
 424 }
 425
 426 static int mtrace_mc_forward_packet(struct pim_instance *pim, struct ip *ip_hdr)
 427 {
 428         pim_sgaddr sg;
 429         struct channel_oil *c_oil;
 430         struct listnode *chnode;
 431         struct listnode *chnextnode;
 432         struct pim_ifchannel *ch = NULL;
 433         int ret = -1;
 434
 435         memset(&sg, 0, sizeof(sg));
 436         sg.grp = ip_hdr->ip_dst;
 437
 438         c_oil = pim_find_channel_oil(pim, &sg);
 439
 440         if (c_oil == NULL) {
 441                 if (PIM_DEBUG_MTRACE) {
 442                         zlog_debug(
 443                                 "Dropping mtrace multicast packet len=%u to %pI4 ttl=%u",
 444                                 ntohs(ip_hdr->ip_len),
 445                                 &ip_hdr->ip_dst, ip_hdr->ip_ttl);
 446                 }
 447                 return -1;
 448         }
 449         if (c_oil->up == NULL)
 450                 return -1;
 451         if (c_oil->up->ifchannels == NULL)
 452                 return -1;
 453         for (ALL_LIST_ELEMENTS(c_oil->up->ifchannels, chnode, chnextnode, ch)) {
 454                 if (pim_macro_chisin_oiflist(ch)) {
 455                         int r;
 456
 457                         r = mtrace_un_forward_packet(pim, ip_hdr,
 458                                                      ch->interface);
 459                         if (r == 0)
 460                                 ret = 0;
 461                 }
 462         }
 463         return ret;
 464 }
 465
 466
 467 static int mtrace_forward_packet(struct pim_instance *pim, struct ip *ip_hdr)
 468 {
 469         if (IPV4_CLASS_DE(ntohl(ip_hdr->ip_dst.s_addr)))
 470                 return mtrace_mc_forward_packet(pim, ip_hdr);
 471         else
 472                 return mtrace_un_forward_packet(pim, ip_hdr, NULL);
 473 }
 474
 475 static int mtrace_send_mc_response(struct pim_instance *pim,
 476                                    struct igmp_mtrace *mtracep,
 477                                    size_t mtrace_len)
 478 {
 479         pim_sgaddr sg;
 480         struct channel_oil *c_oil;
 481         struct listnode *chnode;
 482         struct listnode *chnextnode;
 483         struct pim_ifchannel *ch = NULL;
 484         int ret = -1;
 485
 486         memset(&sg, 0, sizeof(sg));
 487         sg.grp = mtracep->rsp_addr;
 488
 489         c_oil = pim_find_channel_oil(pim, &sg);
 490
 491         if (c_oil == NULL) {
 492                 if (PIM_DEBUG_MTRACE) {
 493                         struct in_addr rsp_addr = mtracep->rsp_addr;
 494
 495                         zlog_debug(
 496                                 "Dropping mtrace multicast response packet len=%u to %pI4",
 497                                 (unsigned int)mtrace_len, &rsp_addr);
 498                 }
 499                 return -1;
 500         }
 501         if (c_oil->up == NULL)
 502                 return -1;
 503         if (c_oil->up->ifchannels == NULL)
 504                 return -1;
 505         for (ALL_LIST_ELEMENTS(c_oil->up->ifchannels, chnode, chnextnode, ch)) {
 506                 if (pim_macro_chisin_oiflist(ch)) {
 507                         int r;
 508
 509                         r = mtrace_send_packet(ch->interface, mtracep,
 510                                                mtrace_len, mtracep->rsp_addr,
 511                                                mtracep->grp_addr);
 512                         if (r == 0)
 513                                 ret = 0;
 514                 }
 515         }
 516         return ret;
 517 }
 518
 519 /* 6.5 Sending Traceroute Responses */
 520 static int mtrace_send_response(struct pim_instance *pim,
 521                                 struct igmp_mtrace *mtracep, size_t mtrace_len)
 522 {
 523         struct pim_nexthop nexthop;
 524
 525         mtracep->type = PIM_IGMP_MTRACE_RESPONSE;
 526
 527         mtracep->checksum = 0;
 528         mtracep->checksum = in_cksum((char *)mtracep, mtrace_len);
 529
 530         if (IPV4_CLASS_DE(ntohl(mtracep->rsp_addr.s_addr))) {
 531                 struct pim_rpf *p_rpf;
 532
 533                 if (pim_rp_i_am_rp(pim, mtracep->rsp_addr))
 534                         return mtrace_send_mc_response(pim, mtracep,
 535                                                        mtrace_len);
 536
 537                 p_rpf = pim_rp_g(pim, mtracep->rsp_addr);
 538
 539                 if (p_rpf == NULL) {
 540                         if (PIM_DEBUG_MTRACE) {
 541                                 struct in_addr rsp_addr = mtracep->rsp_addr;
 542
 543                                 zlog_debug("mtrace no RP for %pI4", &rsp_addr);
 544                         }
 545                         return -1;
 546                 }
 547                 nexthop = p_rpf->source_nexthop;
 548                 if (PIM_DEBUG_MTRACE)
 549                         zlog_debug("mtrace response to RP");
 550         } else {
 551                 memset(&nexthop, 0, sizeof(nexthop));
 552                 /* TODO: should use unicast rib lookup */
 553                 if (!pim_nexthop_lookup(pim, &nexthop, mtracep->rsp_addr, 1)) {
 554                         if (PIM_DEBUG_MTRACE)
 555                                 zlog_debug(
 556                                         "Dropped response qid=%ud, no route to response address",
 557                                         mtracep->qry_id);
 558                         return -1;
 559                 }
 560         }
 561
 562         return mtrace_send_packet(nexthop.interface, mtracep, mtrace_len,
 563                                   mtracep->rsp_addr, mtracep->grp_addr);
 564 }
 565
 566 int igmp_mtrace_recv_qry_req(struct gm_sock *igmp, struct ip *ip_hdr,
 567                              struct in_addr from, const char *from_str,
 568                              char *igmp_msg, int igmp_msg_len)
 569 {
 570         static uint32_t qry_id, qry_src;
 571         char mtrace_buf[MTRACE_HDR_SIZE + MTRACE_MAX_HOPS * MTRACE_RSP_SIZE];
 572         struct interface *ifp;
 573         struct interface *out_ifp = NULL;
 574         struct pim_interface *pim_ifp;
 575         struct pim_instance *pim;
 576         struct igmp_mtrace *mtracep;
 577         struct igmp_mtrace_rsp *rspp;
 578         struct in_addr nh_addr;
 579         enum mtrace_fwd_code fwd_code = MTRACE_FWD_CODE_NO_ERROR;
 580         size_t r_len;
 581         int last_rsp_ind = 0;
 582         size_t mtrace_len;
 583         uint16_t recv_checksum;
 584         uint16_t checksum;
 585         bool reached_source;
 586         bool fwd_info;
 587
 588         ifp = igmp->interface;
 589         pim_ifp = ifp->info;
 590         pim = pim_ifp->pim;
 591
 592         /*
 593          * 6. Router Behaviour
 594          * Check if mtrace packet is addressed elsewhere and forward,
 595          * if applicable
 596          */
 597         if (!IPV4_CLASS_DE(ntohl(ip_hdr->ip_dst.s_addr)))
 598                 if (!if_address_is_local(&ip_hdr->ip_dst, AF_INET,
 599                                          pim->vrf->vrf_id))
 600                         return mtrace_forward_packet(pim, ip_hdr);
 601
 602         if (igmp_msg_len < (int)sizeof(struct igmp_mtrace)) {
 603                 if (PIM_DEBUG_MTRACE)
 604                         zlog_debug(
 605                                 "Recv mtrace packet from %s on %s: too short, len=%d, min=%zu",
 606                                 from_str, ifp->name, igmp_msg_len,
 607                                 sizeof(struct igmp_mtrace));
 608                 return -1;
 609         }
 610
 611         mtracep = (struct igmp_mtrace *)igmp_msg;
 612
 613         recv_checksum = mtracep->checksum;
 614
 615         mtracep->checksum = 0;
 616
 617         checksum = in_cksum(igmp_msg, igmp_msg_len);
 618
 619         if (recv_checksum != checksum) {
 620                 if (PIM_DEBUG_MTRACE)
 621                         zlog_debug(
 622                                 "Recv mtrace packet from %s on %s: checksum mismatch: received=%x computed=%x",
 623                                 from_str, ifp->name, recv_checksum, checksum);
 624                 return -1;
 625         }
 626
 627         /* Collecting IGMP Rx stats */
 628         igmp->igmp_stats.mtrace_req++;
 629
 630         if (PIM_DEBUG_MTRACE)
 631                 mtrace_debug(pim_ifp, mtracep, igmp_msg_len);
 632
 633         /* subtract header from message length */
 634         r_len = igmp_msg_len - sizeof(struct igmp_mtrace);
 635
 636         /* Classify mtrace packet, check if it is a query */
 637         if (!r_len) {
 638                 if (PIM_DEBUG_MTRACE)
 639                         zlog_debug("Received IGMP multicast traceroute query");
 640
 641                 /* 6.1.1  Packet verification */
 642                 if (!pim_if_connected_to_source(ifp, mtracep->dst_addr)) {
 643                         if (IPV4_CLASS_DE(ntohl(ip_hdr->ip_dst.s_addr))) {
 644                                 if (PIM_DEBUG_MTRACE)
 645                                         zlog_debug(
 646                                                 "Dropping multicast query on wrong interface");
 647                                 return -1;
 648                         }
 649                         /* Unicast query on wrong interface */
 650                         fwd_code = MTRACE_FWD_CODE_WRONG_IF;
 651                         if (PIM_DEBUG_MTRACE)
 652                                 zlog_debug("Multicast query on wrong interface");
 653                 }
 654                 if (qry_id == mtracep->qry_id && qry_src == from.s_addr) {
 655                         if (PIM_DEBUG_MTRACE)
 656                                 zlog_debug(
 657                                         "Dropping multicast query with duplicate source and id");
 658                         return -1;
 659                 }
 660                 qry_id = mtracep->qry_id;
 661                 qry_src = from.s_addr;
 662         }
 663         /* if response fields length is equal to a whole number of responses */
 664         else if ((r_len % sizeof(struct igmp_mtrace_rsp)) == 0) {
 665                 r_len = igmp_msg_len - sizeof(struct igmp_mtrace);
 666
 667                 if (r_len != 0)
 668                         last_rsp_ind = r_len / sizeof(struct igmp_mtrace_rsp);
 669                 if (last_rsp_ind > MTRACE_MAX_HOPS) {
 670                         if (PIM_DEBUG_MTRACE)
 671                                 zlog_debug("Mtrace request of excessive size");
 672                         return -1;
 673                 }
 674         } else {
 675                 if (PIM_DEBUG_MTRACE)
 676                         zlog_debug(
 677                                 "Recv mtrace packet from %s on %s: invalid length %d",
 678                                 from_str, ifp->name, igmp_msg_len);
 679                 return -1;
 680         }
 681
 682         /* 6.2.1 Packet Verification - drop not link-local multicast */
 683         if (IPV4_CLASS_DE(ntohl(ip_hdr->ip_dst.s_addr))
 684             && !IPV4_MC_LINKLOCAL(ntohl(ip_hdr->ip_dst.s_addr))) {
 685                 if (PIM_DEBUG_MTRACE)
 686                         zlog_debug(
 687                                 "Recv mtrace packet from %s on %s: not link-local multicast %pI4",
 688                                 from_str, ifp->name, &ip_hdr->ip_dst);
 689                 return -1;
 690         }
 691
 692         /* 6.2.2. Normal Processing */
 693
 694         /* 6.2.2. 1. If there is room in the current buffer? */
 695
 696         if (last_rsp_ind == MTRACE_MAX_HOPS) {
 697                 /* ...there was no room... */
 698                 mtracep->rsp[MTRACE_MAX_HOPS - 1].fwd_code =
 699                         MTRACE_FWD_CODE_NO_SPACE;
 700                 return mtrace_send_response(pim_ifp->pim, mtracep,
 701                                             igmp_msg_len);
 702         }
 703
 704         /* ...insert new response block... */
 705
 706         /* calculate new mtrace lenght with extra response */
 707         mtrace_len = igmp_msg_len + sizeof(struct igmp_mtrace_rsp);
 708
 709         /* copy received query/request */
 710         memcpy(mtrace_buf, igmp_msg, igmp_msg_len);
 711
 712         /* repoint mtracep pointer to copy */
 713         mtracep = (struct igmp_mtrace *)mtrace_buf;
 714
 715         /* pointer for extra response field to be filled in */
 716         rspp = &mtracep->rsp[last_rsp_ind];
 717
 718         /* initialize extra response field */
 719         mtrace_rsp_init(rspp);
 720
 721         /* carry over any error noted when receiving the query */
 722         rspp->fwd_code = fwd_code;
 723
 724         /* ...and fill in Query Arrival Time... */
 725         rspp->arrival = htonl(query_arrival_time());
 726         rspp->outgoing = pim_ifp->primary_address;
 727         rspp->out_count = htonl(MTRACE_UNKNOWN_COUNT);
 728         rspp->fwd_ttl = 1;
 729
 730         /* 6.2.2. 2. Attempt to determine the forwarding information... */
 731
 732         if (mtracep->grp_addr.s_addr != INADDR_ANY)
 733                 fwd_info = mtrace_fwd_info(pim, mtracep, rspp, &out_ifp);
 734         else
 735                 fwd_info = mtrace_fwd_info_weak(pim, mtracep, rspp, &out_ifp);
 736
 737         /* 6.2.2 3. If no forwarding information... */
 738         if (!fwd_info) {
 739                 if (PIM_DEBUG_MTRACE)
 740                         zlog_debug("mtrace not found multicast state");
 741                 mtrace_rsp_set_fwd_code(rspp, MTRACE_FWD_CODE_NO_ROUTE);
 742                 /* 6.2.2. 3. forward the packet to requester */
 743                 return mtrace_send_response(pim, mtracep, mtrace_len);
 744         }
 745
 746         nh_addr = rspp->prev_hop;
 747
 748         reached_source = false;
 749
 750         if (nh_addr.s_addr == INADDR_ANY) {
 751                 /* no pim? i.e. 7.5.3. No Previous Hop */
 752                 if (!out_ifp->info) {
 753                         if (PIM_DEBUG_MTRACE)
 754                                 zlog_debug("mtrace not found incoming if w/ pim");
 755                         mtrace_rsp_set_fwd_code(rspp,
 756                                                 MTRACE_FWD_CODE_NO_MULTICAST);
 757                         return mtrace_send_response(pim, mtracep, mtrace_len);
 758                 }
 759                 /* reached source? i.e. 7.5.1 Arriving at source */
 760                 if (pim_if_connected_to_source(out_ifp, mtracep->src_addr)) {
 761                         reached_source = true;
 762                         rspp->prev_hop = mtracep->src_addr;
 763                 }
 764                 /*
 765                  * 6.4 Forwarding Traceroute Requests:
 766                  * Previous-hop router not known,
 767                  * packet is sent to an appropriate multicast address
 768                  */
 769                 (void)inet_aton(MCAST_ALL_ROUTERS, &nh_addr);
 770         }
 771
 772         /* 6.2.2 8. If this router is the Rendez-vous Point */
 773         if (mtracep->grp_addr.s_addr != INADDR_ANY &&
 774             pim_rp_i_am_rp(pim, mtracep->grp_addr)) {
 775                 mtrace_rsp_set_fwd_code(rspp, MTRACE_FWD_CODE_REACHED_RP);
 776                 /* 7.7.1. PIM-SM ...RP has not performed source-specific join */
 777                 if (rspp->src_mask == MTRACE_SRC_MASK_GROUP)
 778                         return mtrace_send_response(pim, mtracep, mtrace_len);
 779         }
 780
 781         /*
 782          * 6.4 Forwarding Traceroute Requests: the number of response
 783          * blocks exceeds number of responses, so forward to the requester.
 784          */
 785         if (mtracep->hops <= (last_rsp_ind + 1))
 786                 return mtrace_send_response(pim, mtracep, mtrace_len);
 787
 788         /* 7.5.1. Arriving at source: terminate trace */
 789         if (reached_source)
 790                 return mtrace_send_response(pim, mtracep, mtrace_len);
 791
 792         mtracep->checksum = 0;
 793
 794         mtracep->checksum = in_cksum(mtrace_buf, mtrace_len);
 795
 796         /* 6.4 Forwarding Traceroute Requests: response blocks less than req. */
 797         return mtrace_send_packet(out_ifp, mtracep, mtrace_len, nh_addr,
 798                                   mtracep->grp_addr);
 799 }
 800
 801 /* 6.3. Traceroute responses */
 802 int igmp_mtrace_recv_response(struct gm_sock *igmp, struct ip *ip_hdr,
 803                               struct in_addr from, const char *from_str,
 804                               char *igmp_msg, int igmp_msg_len)
 805 {
 806         static uint32_t qry_id, rsp_dst;
 807         struct interface *ifp;
 808         struct pim_interface *pim_ifp;
 809         struct pim_instance *pim;
 810         struct igmp_mtrace *mtracep;
 811         uint16_t recv_checksum;
 812         uint16_t checksum;
 813
 814         ifp = igmp->interface;
 815         pim_ifp = ifp->info;
 816         pim = pim_ifp->pim;
 817
 818         if (igmp_msg_len < (int)sizeof(struct igmp_mtrace)) {
 819                 if (PIM_DEBUG_MTRACE)
 820                         zlog_debug(
 821                                 "Recv mtrace packet from %s on %s: too short, len=%d, min=%zu",
 822                                 from_str, ifp->name, igmp_msg_len,
 823                                 sizeof(struct igmp_mtrace));
 824                 return -1;
 825         }
 826
 827         mtracep = (struct igmp_mtrace *)igmp_msg;
 828
 829         recv_checksum = mtracep->checksum;
 830
 831         mtracep->checksum = 0;
 832
 833         checksum = in_cksum(igmp_msg, igmp_msg_len);
 834
 835         if (recv_checksum != checksum) {
 836                 if (PIM_DEBUG_MTRACE)
 837                         zlog_debug(
 838                                 "Recv mtrace response from %s on %s: checksum mismatch: received=%x computed=%x",
 839                                 from_str, ifp->name, recv_checksum, checksum);
 840                 return -1;
 841         }
 842
 843         mtracep->checksum = checksum;
 844
 845         /* Collecting IGMP Rx stats */
 846         igmp->igmp_stats.mtrace_rsp++;
 847
 848         if (PIM_DEBUG_MTRACE)
 849                 mtrace_debug(pim_ifp, mtracep, igmp_msg_len);
 850
 851         /* Drop duplicate packets */
 852         if (qry_id == mtracep->qry_id && rsp_dst == ip_hdr->ip_dst.s_addr) {
 853                 if (PIM_DEBUG_MTRACE)
 854                         zlog_debug("duplicate mtrace response packet dropped");
 855                 return -1;
 856         }
 857
 858         qry_id = mtracep->qry_id;
 859         rsp_dst = ip_hdr->ip_dst.s_addr;
 860
 861         return mtrace_forward_packet(pim, ip_hdr);
 862 }