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_util.h"
  26 #include "pim_sock.h"
  27 #include "pim_rp.h"
  28 #include "pim_oil.h"
  29 #include "pim_ifchannel.h"
  30 #include "pim_macro.h"
  31 #include "pim_igmp_mtrace.h"
  32
  33 static struct in_addr mtrace_primary_address(struct interface *ifp)
  34 {
  35         struct connected *ifc;
  36         struct listnode *node;
  37         struct in_addr any;
  38         struct pim_interface *pim_ifp;
  39
  40         if (ifp->info) {
  41                 pim_ifp = ifp->info;
  42                 return pim_ifp->primary_address;
  43         }
  44
  45         any.s_addr = INADDR_ANY;
  46
  47         for (ALL_LIST_ELEMENTS_RO(ifp->connected, node, ifc)) {
  48                 struct prefix *p = ifc->address;
  49
  50                 if (p->family != AF_INET)
  51                         continue;
  52
  53                 if (!CHECK_FLAG(ifc->flags, ZEBRA_IFA_SECONDARY))
  54                         return p->u.prefix4;
  55                 /* in case no primary found, return a secondary */
  56                 any = p->u.prefix4;
  57         }
  58         return any;
  59 }
  60
  61 static bool mtrace_fwd_info_weak(struct pim_instance *pim,
  62                                     struct igmp_mtrace *mtracep,
  63                                     struct igmp_mtrace_rsp *rspp,
  64                                     struct interface **ifpp)
  65 {
  66         struct pim_nexthop nexthop;
  67         struct interface *ifp_in;
  68         struct in_addr nh_addr;
  69         int ret;
  70         char nexthop_str[INET_ADDRSTRLEN];
  71
  72         nh_addr.s_addr = 0;
  73
  74         memset(&nexthop, 0, sizeof(nexthop));
  75
  76         ret = pim_nexthop_lookup(pim, &nexthop, mtracep->src_addr, 1);
  77
  78         if (ret != 0) {
  79                 if (PIM_DEBUG_MTRACE)
  80                         zlog_debug("mtrace not found neighbor");
  81                 return false;
  82         }
  83
  84         if (PIM_DEBUG_MTRACE)
  85                 zlog_debug("mtrace pim_nexthop_lookup OK");
  86
  87         if (PIM_DEBUG_MTRACE)
  88                 zlog_warn("mtrace next_hop=%s",
  89                           inet_ntop(nexthop.mrib_nexthop_addr.family,
  90                                     &nexthop.mrib_nexthop_addr.u.prefix,
  91                                     nexthop_str, sizeof(nexthop_str)));
  92
  93         if (nexthop.mrib_nexthop_addr.family == AF_INET)
  94                 nh_addr = nexthop.mrib_nexthop_addr.u.prefix4;
  95
  96         ifp_in = nexthop.interface;
  97
  98         /* return interface for forwarding mtrace packets */
  99         *ifpp = ifp_in;
 100
 101         /* 6.2.2. 4. Fill in the Incoming Interface Address... */
 102         rspp->incoming = mtrace_primary_address(ifp_in);
 103         rspp->prev_hop = nh_addr;
 104         rspp->in_count = htonl(MTRACE_UNKNOWN_COUNT);
 105         rspp->total = htonl(MTRACE_UNKNOWN_COUNT);
 106         rspp->rtg_proto = MTRACE_RTG_PROTO_PIM;
 107         return true;
 108 }
 109
 110 static bool mtrace_fwd_info(struct pim_instance *pim,
 111                             struct igmp_mtrace *mtracep,
 112                             struct igmp_mtrace_rsp *rspp,
 113                             struct interface **ifpp)
 114 {
 115         struct prefix_sg sg;
 116         struct pim_upstream *up;
 117         struct interface *ifp_in;
 118         struct in_addr nh_addr;
 119         uint32_t total;
 120         char up_str[INET_ADDRSTRLEN];
 121
 122         memset(&sg, 0, sizeof(struct prefix_sg));
 123         sg.src = mtracep->src_addr;
 124         sg.grp = mtracep->grp_addr;
 125
 126         up = pim_upstream_find(pim, &sg);
 127
 128         if (!up) {
 129                 sg.src.s_addr = 0;
 130                 up = pim_upstream_find(pim, &sg);
 131         }
 132
 133         if (!up)
 134                 return false;
 135
 136         ifp_in = up->rpf.source_nexthop.interface;
 137         nh_addr = up->rpf.source_nexthop.mrib_nexthop_addr.u.prefix4;
 138         total = htonl(MTRACE_UNKNOWN_COUNT);
 139
 140         if (PIM_DEBUG_MTRACE)
 141                 zlog_debug("fwd_info: upstream next hop=%s",
 142                            inet_ntop(AF_INET, &(nh_addr), up_str,
 143                                      sizeof(up_str)));
 144
 145         if (up->channel_oil)
 146                 total = up->channel_oil->cc.pktcnt;
 147
 148         /* return interface for forwarding mtrace packets */
 149         *ifpp = ifp_in;
 150
 151         /* 6.2.2. 4. Fill in the Incoming Interface Address... */
 152         rspp->incoming = mtrace_primary_address(ifp_in);
 153         rspp->prev_hop = nh_addr;
 154         rspp->in_count = htonl(MTRACE_UNKNOWN_COUNT);
 155         rspp->total = total;
 156         rspp->rtg_proto = MTRACE_RTG_PROTO_PIM;
 157
 158         /* 6.2.2. 4. Fill in ... S, and Src Mask */
 159         if (sg.src.s_addr) {
 160                 rspp->s = 1;
 161                 rspp->src_mask = MTRACE_SRC_MASK_SOURCE;
 162         } else {
 163                 rspp->s = 0;
 164                 rspp->src_mask = MTRACE_SRC_MASK_GROUP;
 165         }
 166
 167         return true;
 168 }
 169
 170 static void mtrace_rsp_set_fwd_code(struct igmp_mtrace_rsp *mtrace_rspp,
 171                                     enum mtrace_fwd_code fwd_code)
 172 {
 173         if (mtrace_rspp->fwd_code == MTRACE_FWD_CODE_NO_ERROR)
 174                 mtrace_rspp->fwd_code = fwd_code;
 175 }
 176
 177 static void mtrace_rsp_init(struct igmp_mtrace_rsp *mtrace_rspp)
 178 {
 179         mtrace_rspp->arrival = 0;
 180         mtrace_rspp->incoming.s_addr = 0;
 181         mtrace_rspp->outgoing.s_addr = 0;
 182         mtrace_rspp->prev_hop.s_addr = 0;
 183         mtrace_rspp->in_count = htonl(MTRACE_UNKNOWN_COUNT);
 184         mtrace_rspp->out_count = htonl(MTRACE_UNKNOWN_COUNT);
 185         mtrace_rspp->total = htonl(MTRACE_UNKNOWN_COUNT);
 186         mtrace_rspp->rtg_proto = 0;
 187         mtrace_rspp->fwd_ttl = 0;
 188         mtrace_rspp->mbz = 0;
 189         mtrace_rspp->s = 0;
 190         mtrace_rspp->src_mask = 0;
 191         mtrace_rspp->fwd_code = MTRACE_FWD_CODE_NO_ERROR;
 192 }
 193
 194 static void mtrace_rsp_debug(uint32_t qry_id, int rsp,
 195                              struct igmp_mtrace_rsp *mrspp)
 196 {
 197         char inc_str[INET_ADDRSTRLEN];
 198         char out_str[INET_ADDRSTRLEN];
 199         char prv_str[INET_ADDRSTRLEN];
 200
 201         zlog_debug(
 202                 "Rx mt(%d) qid=%ud arr=%x in=%s out=%s prev=%s proto=%d fwd=%d",
 203                 rsp, ntohl(qry_id), mrspp->arrival,
 204                 inet_ntop(AF_INET, &(mrspp->incoming), inc_str,
 205                           sizeof(inc_str)),
 206                 inet_ntop(AF_INET, &(mrspp->outgoing), out_str,
 207                           sizeof(out_str)),
 208                 inet_ntop(AF_INET, &(mrspp->prev_hop), prv_str,
 209                           sizeof(prv_str)),
 210                 mrspp->rtg_proto, mrspp->fwd_code);
 211 }
 212
 213 static void mtrace_debug(struct pim_interface *pim_ifp,
 214                          struct igmp_mtrace *mtracep, int mtrace_len)
 215 {
 216         char inc_str[INET_ADDRSTRLEN];
 217         char grp_str[INET_ADDRSTRLEN];
 218         char src_str[INET_ADDRSTRLEN];
 219         char dst_str[INET_ADDRSTRLEN];
 220         char rsp_str[INET_ADDRSTRLEN];
 221
 222         struct in_addr ga, sa, da, ra;
 223
 224         ga = mtracep->grp_addr;
 225         sa = mtracep->src_addr;
 226         da = mtracep->dst_addr;
 227         ra = mtracep->rsp_addr;
 228
 229         zlog_debug(
 230                 "Rx mtrace packet incoming on %s: "
 231                 "hops=%d type=%d size=%d, grp=%s, src=%s,"
 232                 " dst=%s rsp=%s ttl=%d qid=%ud",
 233                 inet_ntop(AF_INET, &(pim_ifp->primary_address), inc_str,
 234                           sizeof(inc_str)),
 235                 mtracep->hops, mtracep->type, mtrace_len,
 236                 inet_ntop(AF_INET, &ga, grp_str,
 237                           sizeof(grp_str)),
 238                 inet_ntop(AF_INET, &sa, src_str,
 239                           sizeof(src_str)),
 240                 inet_ntop(AF_INET, &da, dst_str,
 241                           sizeof(dst_str)),
 242                 inet_ntop(AF_INET, &ra, rsp_str,
 243                           sizeof(rsp_str)),
 244                 mtracep->rsp_ttl, ntohl(mtracep->qry_id));
 245         if (mtrace_len > (int)sizeof(struct igmp_mtrace)) {
 246
 247                 int i;
 248
 249                 int responses = mtrace_len - sizeof(struct igmp_mtrace);
 250
 251                 if ((responses % sizeof(struct igmp_mtrace_rsp)) != 0)
 252                         if (PIM_DEBUG_MTRACE)
 253                                 zlog_debug(
 254                                         "Mtrace response block of wrong"
 255                                         " length");
 256
 257                 responses = responses / sizeof(struct igmp_mtrace_rsp);
 258
 259                 for (i = 0; i < responses; i++)
 260                         mtrace_rsp_debug(mtracep->qry_id, i, &mtracep->rsp[i]);
 261         }
 262 }
 263
 264 /* 5.1 Query Arrival Time */
 265 static uint32_t query_arrival_time(void)
 266 {
 267         struct timeval tv;
 268         uint32_t qat;
 269
 270         char m_qat[] = "Query arrival time lookup failed: errno=%d: %s";
 271
 272         if (gettimeofday(&tv, NULL) < 0) {
 273                 if (PIM_DEBUG_MTRACE)
 274                         zlog_warn(m_qat, errno, safe_strerror(errno));
 275                 return 0;
 276         }
 277         /* not sure second offset correct, as I get different value */
 278         qat = ((tv.tv_sec + 32384) << 16) + ((tv.tv_usec << 10) / 15625);
 279
 280         return qat;
 281 }
 282
 283 static int mtrace_send_packet(struct interface *ifp,
 284                               struct igmp_mtrace *mtracep,
 285                               size_t mtrace_buf_len, struct in_addr dst_addr,
 286                               struct in_addr group_addr)
 287 {
 288         struct sockaddr_in to;
 289         socklen_t tolen;
 290         ssize_t sent;
 291         int ret;
 292         int fd;
 293         char if_str[INET_ADDRSTRLEN];
 294         char rsp_str[INET_ADDRSTRLEN];
 295         uint8_t ttl;
 296
 297         memset(&to, 0, sizeof(to));
 298         to.sin_family = AF_INET;
 299         to.sin_addr = dst_addr;
 300         tolen = sizeof(to);
 301
 302         if (PIM_DEBUG_MTRACE) {
 303                 struct in_addr if_addr;
 304
 305                 if_addr = mtrace_primary_address(ifp);
 306                 zlog_debug(
 307                         "Sending mtrace packet to %s on %s",
 308                         inet_ntop(AF_INET, &mtracep->rsp_addr, rsp_str,
 309                                   sizeof(rsp_str)),
 310                         inet_ntop(AF_INET, &if_addr, if_str, sizeof(if_str)));
 311         }
 312
 313         fd = pim_socket_raw(IPPROTO_IGMP);
 314
 315         if (fd < 0)
 316                 return -1;
 317
 318         ret = pim_socket_bind(fd, ifp);
 319
 320         if (ret < 0) {
 321                 ret = -1;
 322                 goto close_fd;
 323         }
 324
 325         if (IPV4_CLASS_DE(ntohl(dst_addr.s_addr))) {
 326                 if (IPV4_MC_LINKLOCAL(ntohl(dst_addr.s_addr))) {
 327                         ttl = 1;
 328                 } else {
 329                         if (mtracep->type == PIM_IGMP_MTRACE_RESPONSE)
 330                                 ttl = mtracep->rsp_ttl;
 331                         else
 332                                 ttl = 64;
 333                 }
 334                 ret = setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl,
 335                                  sizeof(ttl));
 336
 337                 if (ret < 0) {
 338                         if (PIM_DEBUG_MTRACE)
 339                                 zlog_warn("Failed to set socket multicast TTL");
 340                         ret = -1;
 341                         goto close_fd;
 342                 }
 343         }
 344
 345         sent = sendto(fd, (char *)mtracep, mtrace_buf_len, MSG_DONTWAIT,
 346                       (struct sockaddr *)&to, tolen);
 347
 348         if (sent != (ssize_t)mtrace_buf_len) {
 349                 char dst_str[INET_ADDRSTRLEN];
 350                 char group_str[INET_ADDRSTRLEN];
 351
 352                 pim_inet4_dump("<dst?>", dst_addr, dst_str, sizeof(dst_str));
 353                 pim_inet4_dump("<group?>", group_addr, group_str,
 354                                sizeof(group_str));
 355                 if (sent < 0) {
 356                         if (PIM_DEBUG_MTRACE)
 357                                 zlog_warn(
 358                                         "Send mtrace request failed for %s on"
 359                                         "%s: group=%s msg_size=%zd: errno=%d: "
 360                                         " %s",
 361                                         dst_str, ifp->name, group_str,
 362                                         mtrace_buf_len, errno,
 363                                         safe_strerror(errno));
 364                 } else {
 365                         if (PIM_DEBUG_MTRACE)
 366                                 zlog_warn(
 367                                         "Send mtrace request failed for %s on"
 368                                         " %s: group=%s msg_size=%zd: sent=%zd",
 369                                         dst_str, ifp->name, group_str,
 370                                         mtrace_buf_len, sent);
 371                 }
 372                 ret = -1;
 373                 goto close_fd;
 374         }
 375         ret = 0;
 376 close_fd:
 377         close(fd);
 378         return ret;
 379 }
 380
 381 static int mtrace_un_forward_packet(struct pim_instance *pim, struct ip *ip_hdr,
 382                                     struct interface *interface)
 383 {
 384         struct pim_nexthop nexthop;
 385         struct sockaddr_in to;
 386         struct interface *if_out;
 387         socklen_t tolen;
 388         int ret;
 389         int fd;
 390         int sent;
 391         uint16_t checksum;
 392
 393         checksum = ip_hdr->ip_sum;
 394
 395         ip_hdr->ip_sum = 0;
 396
 397         if (checksum != in_cksum(ip_hdr, ip_hdr->ip_hl * 4))
 398                 return -1;
 399
 400         if (ip_hdr->ip_ttl-- <= 1)
 401                 return -1;
 402
 403         ip_hdr->ip_sum = in_cksum(ip_hdr, ip_hdr->ip_hl * 4);
 404
 405         fd = pim_socket_raw(IPPROTO_RAW);
 406
 407         if (fd < 0)
 408                 return -1;
 409
 410         pim_socket_ip_hdr(fd);
 411
 412         if (interface == NULL) {
 413                 memset(&nexthop, 0, sizeof(nexthop));
 414                 ret = pim_nexthop_lookup(pim, &nexthop, ip_hdr->ip_dst, 0);
 415
 416                 if (ret != 0) {
 417                         close(fd);
 418                         if (PIM_DEBUG_MTRACE)
 419                                 zlog_warn(
 420                                         "Dropping mtrace packet, "
 421                                         "no route to destination");
 422                         return -1;
 423                 }
 424
 425                 if_out = nexthop.interface;
 426         } else {
 427                 if_out = interface;
 428         }
 429
 430         ret = pim_socket_bind(fd, if_out);
 431
 432         if (ret < 0) {
 433                 close(fd);
 434                 return -1;
 435         }
 436
 437         memset(&to, 0, sizeof(to));
 438         to.sin_family = AF_INET;
 439         to.sin_addr = ip_hdr->ip_dst;
 440         tolen = sizeof(to);
 441
 442         sent = sendto(fd, ip_hdr, ntohs(ip_hdr->ip_len), 0,
 443                       (struct sockaddr *)&to, tolen);
 444
 445         close(fd);
 446
 447         if (sent < 0) {
 448                 if (PIM_DEBUG_MTRACE)
 449                         zlog_warn(
 450                                 "Failed to forward mtrace packet:"
 451                                 " sendto errno=%d, %s",
 452                                 errno, safe_strerror(errno));
 453                 return -1;
 454         }
 455
 456         if (PIM_DEBUG_MTRACE) {
 457                 zlog_debug("Fwd mtrace packet len=%u to %s ttl=%u",
 458                            ntohs(ip_hdr->ip_len), inet_ntoa(ip_hdr->ip_dst),
 459                            ip_hdr->ip_ttl);
 460         }
 461
 462         return 0;
 463 }
 464
 465 static int mtrace_mc_forward_packet(struct pim_instance *pim, struct ip *ip_hdr)
 466 {
 467         struct prefix_sg sg;
 468         struct channel_oil *c_oil;
 469         struct listnode *chnode;
 470         struct listnode *chnextnode;
 471         struct pim_ifchannel *ch = NULL;
 472         int ret = -1;
 473
 474         memset(&sg, 0, sizeof(struct prefix_sg));
 475         sg.grp = ip_hdr->ip_dst;
 476
 477         c_oil = pim_find_channel_oil(pim, &sg);
 478
 479         if (c_oil == NULL) {
 480                 if (PIM_DEBUG_MTRACE) {
 481                         zlog_debug(
 482                                 "Dropping mtrace multicast packet "
 483                                 "len=%u to %s ttl=%u",
 484                                 ntohs(ip_hdr->ip_len),
 485                                 inet_ntoa(ip_hdr->ip_dst), ip_hdr->ip_ttl);
 486                 }
 487                 return -1;
 488         }
 489         if (c_oil->up == NULL)
 490                 return -1;
 491         if (c_oil->up->ifchannels == NULL)
 492                 return -1;
 493         for (ALL_LIST_ELEMENTS(c_oil->up->ifchannels, chnode, chnextnode, ch)) {
 494                 if (pim_macro_chisin_oiflist(ch)) {
 495                         int r;
 496
 497                         r = mtrace_un_forward_packet(pim, ip_hdr,
 498                                                      ch->interface);
 499                         if (r == 0)
 500                                 ret = 0;
 501                 }
 502         }
 503         return ret;
 504 }
 505
 506
 507 static int mtrace_forward_packet(struct pim_instance *pim, struct ip *ip_hdr)
 508 {
 509         if (IPV4_CLASS_DE(ntohl(ip_hdr->ip_dst.s_addr)))
 510                 return mtrace_mc_forward_packet(pim, ip_hdr);
 511         else
 512                 return mtrace_un_forward_packet(pim, ip_hdr, NULL);
 513 }
 514
 515 static int mtrace_send_mc_response(struct pim_instance *pim,
 516                                    struct igmp_mtrace *mtracep,
 517                                    size_t mtrace_len)
 518 {
 519         struct prefix_sg sg;
 520         struct channel_oil *c_oil;
 521         struct listnode *chnode;
 522         struct listnode *chnextnode;
 523         struct pim_ifchannel *ch = NULL;
 524         int ret = -1;
 525
 526         memset(&sg, 0, sizeof(struct prefix_sg));
 527         sg.grp = mtracep->rsp_addr;
 528
 529         c_oil = pim_find_channel_oil(pim, &sg);
 530
 531         if (c_oil == NULL) {
 532                 if (PIM_DEBUG_MTRACE) {
 533                         zlog_debug(
 534                                 "Dropping mtrace multicast response packet "
 535                                 "len=%u to %s",
 536                                 (unsigned int)mtrace_len,
 537                                 inet_ntoa(mtracep->rsp_addr));
 538                 }
 539                 return -1;
 540         }
 541         if (c_oil->up == NULL)
 542                 return -1;
 543         if (c_oil->up->ifchannels == NULL)
 544                 return -1;
 545         for (ALL_LIST_ELEMENTS(c_oil->up->ifchannels, chnode, chnextnode, ch)) {
 546                 if (pim_macro_chisin_oiflist(ch)) {
 547                         int r;
 548
 549                         r = mtrace_send_packet(ch->interface, mtracep,
 550                                                mtrace_len, mtracep->rsp_addr,
 551                                                mtracep->grp_addr);
 552                         if (r == 0)
 553                                 ret = 0;
 554                 }
 555         }
 556         return ret;
 557 }
 558
 559 /* 6.5 Sending Traceroute Responses */
 560 static int mtrace_send_response(struct pim_instance *pim,
 561                                 struct igmp_mtrace *mtracep, size_t mtrace_len)
 562 {
 563         struct pim_nexthop nexthop;
 564         int ret;
 565
 566         mtracep->type = PIM_IGMP_MTRACE_RESPONSE;
 567
 568         mtracep->checksum = 0;
 569         mtracep->checksum = in_cksum((char *)mtracep, mtrace_len);
 570
 571         if (IPV4_CLASS_DE(ntohl(mtracep->rsp_addr.s_addr))) {
 572                 struct pim_rpf *p_rpf;
 573                 char grp_str[INET_ADDRSTRLEN];
 574
 575                 if (pim_rp_i_am_rp(pim, mtracep->rsp_addr))
 576                         return mtrace_send_mc_response(pim, mtracep,
 577                                                        mtrace_len);
 578
 579                 p_rpf = pim_rp_g(pim, mtracep->rsp_addr);
 580
 581                 if (p_rpf == NULL) {
 582                         if (PIM_DEBUG_MTRACE)
 583                                 zlog_warn("mtrace no RP for %s",
 584                                           inet_ntop(AF_INET,
 585                                                     &(mtracep->rsp_addr),
 586                                                     grp_str, sizeof(grp_str)));
 587                         return -1;
 588                 }
 589                 nexthop = p_rpf->source_nexthop;
 590                 if (PIM_DEBUG_MTRACE)
 591                         zlog_debug("mtrace response to RP");
 592         } else {
 593                 memset(&nexthop, 0, sizeof(nexthop));
 594                 /* TODO: should use unicast rib lookup */
 595                 ret = pim_nexthop_lookup(pim, &nexthop, mtracep->rsp_addr, 1);
 596
 597                 if (ret != 0) {
 598                         if (PIM_DEBUG_MTRACE)
 599                                 zlog_warn(
 600                                         "Dropped response qid=%ud, no route to "
 601                                         "response address",
 602                                         mtracep->qry_id);
 603                         return -1;
 604                 }
 605         }
 606
 607         return mtrace_send_packet(nexthop.interface, mtracep, mtrace_len,
 608                                   mtracep->rsp_addr, mtracep->grp_addr);
 609 }
 610
 611 int igmp_mtrace_recv_qry_req(struct igmp_sock *igmp, struct ip *ip_hdr,
 612                              struct in_addr from, const char *from_str,
 613                              char *igmp_msg, int igmp_msg_len)
 614 {
 615         static uint32_t qry_id, qry_src;
 616         char mtrace_buf[MTRACE_HDR_SIZE + MTRACE_MAX_HOPS * MTRACE_RSP_SIZE];
 617         struct interface *ifp;
 618         struct interface *out_ifp = NULL;
 619         struct pim_interface *pim_ifp;
 620         struct pim_instance *pim;
 621         struct igmp_mtrace *mtracep;
 622         struct igmp_mtrace_rsp *rspp;
 623         struct in_addr nh_addr;
 624         enum mtrace_fwd_code fwd_code = MTRACE_FWD_CODE_NO_ERROR;
 625         size_t r_len;
 626         int last_rsp_ind = 0;
 627         size_t mtrace_len;
 628         uint16_t recv_checksum;
 629         uint16_t checksum;
 630         bool reached_source;
 631         bool fwd_info;
 632
 633         ifp = igmp->interface;
 634         pim_ifp = ifp->info;
 635         pim = pim_ifp->pim;
 636
 637         /*
 638          * 6. Router Behaviour
 639          * Check if mtrace packet is addressed elsewhere and forward,
 640          * if applicable
 641          */
 642         if (!IPV4_CLASS_DE(ntohl(ip_hdr->ip_dst.s_addr)))
 643                 if (!if_lookup_exact_address(&ip_hdr->ip_dst, AF_INET,
 644                                              pim->vrf_id))
 645                         return mtrace_forward_packet(pim, ip_hdr);
 646
 647         if (igmp_msg_len < (int)sizeof(struct igmp_mtrace)) {
 648                 if (PIM_DEBUG_MTRACE)
 649                         zlog_warn(
 650                                 "Recv mtrace packet from %s on %s: too short,"
 651                                 " len=%d, min=%zu",
 652                                 from_str, ifp->name, igmp_msg_len,
 653                                 sizeof(struct igmp_mtrace));
 654                 return -1;
 655         }
 656
 657         mtracep = (struct igmp_mtrace *)igmp_msg;
 658
 659         recv_checksum = mtracep->checksum;
 660
 661         mtracep->checksum = 0;
 662
 663         checksum = in_cksum(igmp_msg, igmp_msg_len);
 664
 665         if (recv_checksum != checksum) {
 666                 if (PIM_DEBUG_MTRACE)
 667                         zlog_warn(
 668                                 "Recv mtrace packet from %s on %s: checksum"
 669                                 " mismatch: received=%x computed=%x",
 670                                 from_str, ifp->name, recv_checksum, checksum);
 671                 return -1;
 672         }
 673
 674         /* Collecting IGMP Rx stats */
 675         igmp->rx_stats.mtrace_req++;
 676
 677         if (PIM_DEBUG_MTRACE)
 678                 mtrace_debug(pim_ifp, mtracep, igmp_msg_len);
 679
 680         /* subtract header from message length */
 681         r_len = igmp_msg_len - sizeof(struct igmp_mtrace);
 682
 683         /* Classify mtrace packet, check if it is a query */
 684         if (!r_len) {
 685                 if (PIM_DEBUG_MTRACE)
 686                         zlog_debug("Received IGMP multicast traceroute query");
 687
 688                 /* 6.1.1  Packet verification */
 689                 if (!pim_if_connected_to_source(ifp, mtracep->dst_addr)) {
 690                         if (IPV4_CLASS_DE(ntohl(ip_hdr->ip_dst.s_addr))) {
 691                                 if (PIM_DEBUG_MTRACE)
 692                                         zlog_debug(
 693                                                 "Dropping multicast query "
 694                                                 "on wrong interface");
 695                                 return -1;
 696                         }
 697                         /* Unicast query on wrong interface */
 698                         fwd_code = MTRACE_FWD_CODE_WRONG_IF;
 699                         if (PIM_DEBUG_MTRACE)
 700                                 zlog_debug("Multicast query on wrong interface");
 701                 }
 702                 if (qry_id == mtracep->qry_id && qry_src == from.s_addr) {
 703                         if (PIM_DEBUG_MTRACE)
 704                                 zlog_debug(
 705                                         "Dropping multicast query with "
 706                                         "duplicate source and id");
 707                         return -1;
 708                 }
 709                 qry_id = mtracep->qry_id;
 710                 qry_src = from.s_addr;
 711         }
 712         /* if response fields length is equal to a whole number of responses */
 713         else if ((r_len % sizeof(struct igmp_mtrace_rsp)) == 0) {
 714                 r_len = igmp_msg_len - sizeof(struct igmp_mtrace);
 715
 716                 if (r_len != 0)
 717                         last_rsp_ind = r_len / sizeof(struct igmp_mtrace_rsp);
 718                 if (last_rsp_ind > MTRACE_MAX_HOPS) {
 719                         if (PIM_DEBUG_MTRACE)
 720                                 zlog_warn("Mtrace request of excessive size");
 721                         return -1;
 722                 }
 723         } else {
 724                 if (PIM_DEBUG_MTRACE)
 725                         zlog_warn(
 726                                 "Recv mtrace packet from %s on %s: "
 727                                 "invalid length %d",
 728                                 from_str, ifp->name, igmp_msg_len);
 729                 return -1;
 730         }
 731
 732         /* 6.2.1 Packet Verification - drop not link-local multicast */
 733         if (IPV4_CLASS_DE(ntohl(ip_hdr->ip_dst.s_addr))
 734             && !IPV4_MC_LINKLOCAL(ntohl(ip_hdr->ip_dst.s_addr))) {
 735                 if (PIM_DEBUG_MTRACE)
 736                         zlog_warn(
 737                                 "Recv mtrace packet from %s on %s:"
 738                                 " not link-local multicast %s",
 739                                 from_str, ifp->name, inet_ntoa(ip_hdr->ip_dst));
 740                 return -1;
 741         }
 742
 743         /* 6.2.2. Normal Processing */
 744
 745         /* 6.2.2. 1. If there is room in the current buffer? */
 746
 747         if (last_rsp_ind == MTRACE_MAX_HOPS) {
 748                 /* ...there was no room... */
 749                 mtracep->rsp[MTRACE_MAX_HOPS - 1].fwd_code =
 750                         MTRACE_FWD_CODE_NO_SPACE;
 751                 return mtrace_send_response(pim_ifp->pim, mtracep,
 752                                             igmp_msg_len);
 753         }
 754
 755         /* ...insert new response block... */
 756
 757         /* calculate new mtrace lenght with extra response */
 758         mtrace_len = igmp_msg_len + sizeof(struct igmp_mtrace_rsp);
 759
 760         /* copy received query/request */
 761         memcpy(mtrace_buf, igmp_msg, igmp_msg_len);
 762
 763         /* repoint mtracep pointer to copy */
 764         mtracep = (struct igmp_mtrace *)mtrace_buf;
 765
 766         /* pointer for extra response field to be filled in */
 767         rspp = &mtracep->rsp[last_rsp_ind];
 768
 769         /* initialize extra response field */
 770         mtrace_rsp_init(rspp);
 771
 772         /* carry over any error noted when receiving the query */
 773         rspp->fwd_code = fwd_code;
 774
 775         /* ...and fill in Query Arrival Time... */
 776         rspp->arrival = htonl(query_arrival_time());
 777         rspp->outgoing = pim_ifp->primary_address;
 778         rspp->out_count = htonl(MTRACE_UNKNOWN_COUNT);
 779         rspp->fwd_ttl = 1;
 780
 781         /* 6.2.2. 2. Attempt to determine the forwarding information... */
 782
 783         if (mtracep->grp_addr.s_addr)
 784                 fwd_info = mtrace_fwd_info(pim, mtracep, rspp, &out_ifp);
 785         else
 786                 fwd_info = mtrace_fwd_info_weak(pim, mtracep, rspp, &out_ifp);
 787
 788         /* 6.2.2 3. If no forwarding information... */
 789         if (!fwd_info) {
 790                 if (PIM_DEBUG_MTRACE)
 791                         zlog_debug("mtrace not found multicast state");
 792                 mtrace_rsp_set_fwd_code(rspp, MTRACE_FWD_CODE_NO_ROUTE);
 793                 /* 6.2.2. 3. forward the packet to requester */
 794                 return mtrace_send_response(pim, mtracep, mtrace_len);
 795         }
 796
 797         nh_addr = rspp->prev_hop;
 798
 799         reached_source = false;
 800
 801         if (nh_addr.s_addr == 0) {
 802                 /* no pim? i.e. 7.5.3. No Previous Hop */
 803                 if (!out_ifp->info) {
 804                         if (PIM_DEBUG_MTRACE)
 805                                 zlog_debug("mtrace not found incoming if w/ pim");
 806                         mtrace_rsp_set_fwd_code(rspp,
 807                                                 MTRACE_FWD_CODE_NO_MULTICAST);
 808                         return mtrace_send_response(pim, mtracep, mtrace_len);
 809                 }
 810                 /* reached source? i.e. 7.5.1 Arriving at source */
 811                 if (pim_if_connected_to_source(out_ifp, mtracep->src_addr)) {
 812                         reached_source = true;
 813                         rspp->prev_hop = mtracep->src_addr;
 814                 }
 815                 /*
 816                  * 6.4 Forwarding Traceroute Requests:
 817                  * Previous-hop router not known,
 818                  * packet is sent to an appropriate multicast address
 819                  */
 820                 (void)inet_aton(MCAST_ALL_ROUTERS, &nh_addr);
 821         }
 822
 823         /* 6.2.2 8. If this router is the Rendez-vous Point */
 824         if (pim_rp_i_am_rp(pim, mtracep->grp_addr)) {
 825                 mtrace_rsp_set_fwd_code(rspp, MTRACE_FWD_CODE_REACHED_RP);
 826                 /* 7.7.1. PIM-SM ...RP has not performed source-specific join */
 827                 if (rspp->src_mask == MTRACE_SRC_MASK_GROUP)
 828                         return mtrace_send_response(pim, mtracep, mtrace_len);
 829         }
 830
 831         /*
 832          * 6.4 Forwarding Traceroute Requests: the number of response
 833          * blocks exceeds number of responses, so forward to the requester.
 834          */
 835         if (mtracep->hops <= (last_rsp_ind + 1))
 836                 return mtrace_send_response(pim, mtracep, mtrace_len);
 837
 838         /* 7.5.1. Arriving at source: terminate trace */
 839         if (reached_source)
 840                 return mtrace_send_response(pim, mtracep, mtrace_len);
 841
 842         mtracep->checksum = 0;
 843
 844         mtracep->checksum = in_cksum(mtrace_buf, mtrace_len);
 845
 846         /* 6.4 Forwarding Traceroute Requests: response blocks less than req. */
 847         return mtrace_send_packet(out_ifp, mtracep, mtrace_len, nh_addr,
 848                                   mtracep->grp_addr);
 849 }
 850
 851 /* 6.3. Traceroute responses */
 852 int igmp_mtrace_recv_response(struct igmp_sock *igmp, struct ip *ip_hdr,
 853                               struct in_addr from, const char *from_str,
 854                               char *igmp_msg, int igmp_msg_len)
 855 {
 856         static uint32_t qry_id, rsp_dst;
 857         struct interface *ifp;
 858         struct pim_interface *pim_ifp;
 859         struct pim_instance *pim;
 860         struct igmp_mtrace *mtracep;
 861         uint16_t recv_checksum;
 862         uint16_t checksum;
 863
 864         ifp = igmp->interface;
 865         pim_ifp = ifp->info;
 866         pim = pim_ifp->pim;
 867
 868         mtracep = (struct igmp_mtrace *)igmp_msg;
 869
 870         recv_checksum = mtracep->checksum;
 871
 872         mtracep->checksum = 0;
 873
 874         checksum = in_cksum(igmp_msg, igmp_msg_len);
 875
 876         if (recv_checksum != checksum) {
 877                 if (PIM_DEBUG_MTRACE)
 878                         zlog_warn(
 879                                 "Recv mtrace response from %s on %s: checksum"
 880                                 " mismatch: received=%x computed=%x",
 881                                 from_str, ifp->name, recv_checksum, checksum);
 882                 return -1;
 883         }
 884
 885         mtracep->checksum = checksum;
 886
 887         /* Collecting IGMP Rx stats */
 888         igmp->rx_stats.mtrace_rsp++;
 889
 890         if (PIM_DEBUG_MTRACE)
 891                 mtrace_debug(pim_ifp, mtracep, igmp_msg_len);
 892
 893         /* Drop duplicate packets */
 894         if (qry_id == mtracep->qry_id && rsp_dst == ip_hdr->ip_dst.s_addr) {
 895                 if (PIM_DEBUG_MTRACE)
 896                         zlog_debug("duplicate mtrace response packet dropped");
 897                 return -1;
 898         }
 899
 900         qry_id = mtracep->qry_id;
 901         rsp_dst = ip_hdr->ip_dst.s_addr;
 902
 903         return mtrace_forward_packet(pim, ip_hdr);
 904 }