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