pimd/mtracebis.c

   1 /*
   2  * Multicast Traceroute for FRRouting
   3  * Copyright (C) 2018  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 #ifdef HAVE_CONFIG_H
  21 #include "config.h"
  22 #endif
  23
  24 #ifdef __linux__
  25
  26 #include "pim_igmp_mtrace.h"
  27
  28 #include "checksum.h"
  29 #include "prefix.h"
  30 #include "mtracebis_routeget.h"
  31
  32 #include <sys/select.h>
  33 #include <netinet/in.h>
  34 #include <arpa/inet.h>
  35 #include <unistd.h>
  36 #include <sys/types.h>
  37 #include <sys/time.h>
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <string.h>
  41 #include <time.h>
  42 #include <net/if.h>
  43 #include <unistd.h>
  44 #include <getopt.h>
  45 #include <netdb.h>
  46
  47 #define MTRACEBIS_VERSION "0.1"
  48 #define MTRACE_TIMEOUT (5)
  49
  50 #define IP_HDR_LEN (sizeof(struct ip))
  51 #define IP_RA_LEN (4)
  52 #define MTRACE_BUF_LEN (MTRACE_HDR_SIZE + (MTRACE_MAX_HOPS * MTRACE_RSP_SIZE))
  53 #define IP_AND_MTRACE_BUF_LEN (IP_HDR_LEN + IP_RA_LEN + MTRACE_BUF_LEN)
  54
  55 static const char *progname;
  56 static void usage(void)
  57 {
  58         fprintf(stderr, "Usage : %s <multicast source> [<multicast group>]\n",
  59                 progname);
  60 }
  61 static void version(void)
  62 {
  63         fprintf(stderr, "%s %s\n", progname, MTRACEBIS_VERSION);
  64 }
  65
  66 static void print_host(struct in_addr addr)
  67 {
  68         struct hostent *h;
  69
  70         h = gethostbyaddr(&addr, sizeof(addr), AF_INET);
  71         if (h == NULL)
  72                 printf("?");
  73         else
  74                 printf("%s", h->h_name);
  75         printf(" (%s) ", inet_ntoa(addr));
  76 }
  77
  78 static void print_line_no(int i)
  79 {
  80         printf("%3d  ", -i);
  81 }
  82
  83 static const char *rtg_proto_str(enum mtrace_rtg_proto proto)
  84 {
  85         static char buf[80];
  86
  87         buf[0] = '\0';
  88
  89         switch (proto) {
  90         case MTRACE_RTG_PROTO_DVMRP:
  91                 return "DVMRP";
  92         case MTRACE_RTG_PROTO_MOSPF:
  93                 return "MOSPF";
  94         case MTRACE_RTG_PROTO_PIM:
  95                 return "PIM";
  96         case MTRACE_RTG_PROTO_CBT:
  97                 return "CBT";
  98         case MTRACE_RTG_PROTO_PIM_SPECIAL:
  99                 return "PIM special";
 100         case MTRACE_RTG_PROTO_PIM_STATIC:
 101                 return "PIM static";
 102         case MTRACE_RTG_PROTO_DVMRP_STATIC:
 103                 return "DVMRP static";
 104         case MTRACE_RTG_PROTO_PIM_MBGP:
 105                 return "PIM MBGP";
 106         case MTRACE_RTG_PROTO_CBT_SPECIAL:
 107                 return "CBT special";
 108         case MTRACE_RTG_PROTO_CBT_STATIC:
 109                 return "CBT static";
 110         case MTRACE_RTG_PROTO_PIM_ASSERT:
 111                 return "PIM assert";
 112         default:
 113                 sprintf(buf, "unknown protocol (%d)", proto);
 114                 return buf;
 115         }
 116 }
 117
 118 static void print_rtg_proto(uint32_t rtg_proto)
 119 {
 120         printf("%s", rtg_proto_str(rtg_proto));
 121 }
 122
 123 static void print_fwd_ttl(uint32_t fwd_ttl)
 124 {
 125         printf("thresh^ %d", fwd_ttl);
 126 }
 127
 128 static const char *fwd_code_str(enum mtrace_fwd_code code)
 129 {
 130         static char buf[80];
 131
 132         buf[0] = '\0';
 133
 134         switch (code) {
 135         case MTRACE_FWD_CODE_NO_ERROR:
 136                 return "no error";
 137         case MTRACE_FWD_CODE_WRONG_IF:
 138                 return "wrong interface";
 139         case MTRACE_FWD_CODE_PRUNE_SENT:
 140                 return "prune sent";
 141         case MTRACE_FWD_CODE_PRUNE_RCVD:
 142                 return "prune received";
 143         case MTRACE_FWD_CODE_SCOPED:
 144                 return "scoped";
 145         case MTRACE_FWD_CODE_NO_ROUTE:
 146                 return "no route";
 147         case MTRACE_FWD_CODE_WRONG_LAST_HOP:
 148                 return "wrong last hop";
 149         case MTRACE_FWD_CODE_NOT_FORWARDING:
 150                 return "not forwarding";
 151         case MTRACE_FWD_CODE_REACHED_RP:
 152                 return "reached RP";
 153         case MTRACE_FWD_CODE_RPF_IF:
 154                 return "RPF interface";
 155         case MTRACE_FWD_CODE_NO_MULTICAST:
 156                 return "no multicast";
 157         case MTRACE_FWD_CODE_INFO_HIDDEN:
 158                 return "info hidden";
 159         case MTRACE_FWD_CODE_NO_SPACE:
 160                 return "no space";
 161         case MTRACE_FWD_CODE_OLD_ROUTER:
 162                 return "old router";
 163         case MTRACE_FWD_CODE_ADMIN_PROHIB:
 164                 return "admin. prohib.";
 165         default:
 166                 sprintf(buf, "unknown fwd. code (%d)", code);
 167                 return buf;
 168         }
 169 }
 170
 171 static void print_fwd_code(uint32_t fwd_code)
 172 {
 173         printf("%s", fwd_code_str(fwd_code));
 174 }
 175
 176 static void print_rsp(struct igmp_mtrace_rsp *rsp)
 177 {
 178         print_host(rsp->outgoing);
 179         if (rsp->fwd_code == 0 || rsp->fwd_code == MTRACE_FWD_CODE_REACHED_RP) {
 180                 print_rtg_proto(rsp->rtg_proto);
 181                 printf(" ");
 182                 if (rsp->fwd_code == MTRACE_FWD_CODE_REACHED_RP)
 183                         printf("(RP) ");
 184                 if (rsp->rtg_proto == MTRACE_RTG_PROTO_PIM) {
 185                         switch (rsp->src_mask) {
 186                         case MTRACE_SRC_MASK_GROUP:
 187                                 printf("(*,G) ");
 188                                 break;
 189                         case MTRACE_SRC_MASK_SOURCE:
 190                                 printf("(S,G) ");
 191                                 break;
 192                         }
 193                 }
 194                 print_fwd_ttl(rsp->fwd_ttl);
 195         } else {
 196                 print_fwd_code(rsp->fwd_code);
 197         }
 198         printf("\n");
 199 }
 200
 201 static void print_dest(struct igmp_mtrace *mtrace)
 202 {
 203         print_line_no(0);
 204         print_host(mtrace->dst_addr);
 205         printf("\n");
 206 }
 207
 208 static void print_summary(struct igmp_mtrace *mtrace, int hops, long msec)
 209 {
 210         int i;
 211         int t = 0;
 212
 213         for (i = 0; i < hops; i++)
 214                 t += mtrace->rsp[i].fwd_ttl;
 215
 216         printf("Round trip time %ld ms; total ttl of %d required.\n", msec, t);
 217 }
 218
 219 static void print_responses(struct igmp_mtrace *mtrace, int hops, long msec)
 220 {
 221         int i;
 222
 223         print_dest(mtrace);
 224
 225         for (i = 0; i < hops; i++) {
 226                 print_line_no(i + 1);
 227                 print_rsp(&mtrace->rsp[i]);
 228         }
 229         print_summary(mtrace, hops, msec);
 230 }
 231
 232 static int send_query(int fd, struct in_addr to_addr,
 233                       struct igmp_mtrace *mtrace)
 234 {
 235         struct sockaddr_in to;
 236         socklen_t tolen;
 237         int sent;
 238
 239         memset(&to, 0, sizeof(to));
 240         to.sin_family = AF_INET;
 241         to.sin_addr = to_addr;
 242         tolen = sizeof(to);
 243
 244         sent = sendto(fd, (char *)mtrace, sizeof(*mtrace), MSG_DONTWAIT,
 245                       (struct sockaddr *)&to, tolen);
 246
 247         if (sent < 1)
 248                 return -1;
 249         return 0;
 250 }
 251
 252 static void print_query(struct igmp_mtrace *mtrace)
 253 {
 254         char src_str[INET_ADDRSTRLEN];
 255         char dst_str[INET_ADDRSTRLEN];
 256         char grp_str[INET_ADDRSTRLEN];
 257
 258         printf("* Mtrace from %s to %s via group %s\n",
 259                inet_ntop(AF_INET, &mtrace->src_addr, src_str, sizeof(src_str)),
 260                inet_ntop(AF_INET, &mtrace->dst_addr, dst_str, sizeof(dst_str)),
 261                inet_ntop(AF_INET, &mtrace->grp_addr, grp_str, sizeof(grp_str)));
 262 }
 263
 264 static int recv_response(int fd, int *hops, struct igmp_mtrace *mtracer)
 265 {
 266         int recvd;
 267         char mtrace_buf[IP_AND_MTRACE_BUF_LEN];
 268         struct ip *ip;
 269         struct igmp_mtrace *mtrace;
 270         int mtrace_len;
 271         int responses;
 272         unsigned short sum;
 273         size_t mtrace_off;
 274         size_t ip_len;
 275
 276         recvd = recvfrom(fd, mtrace_buf, IP_AND_MTRACE_BUF_LEN, 0, NULL, 0);
 277
 278         if (recvd < 1) {
 279                 fprintf(stderr, "recvfrom error: %s\n", strerror(errno));
 280                 return -1;
 281         }
 282
 283         if (recvd < (int)sizeof(struct ip)) {
 284                 fprintf(stderr, "no ip header\n");
 285                 return -1;
 286         }
 287
 288         ip = (struct ip *)mtrace_buf;
 289
 290         if (ip->ip_v != 4) {
 291                 fprintf(stderr, "IP not version 4\n");
 292                 return -1;
 293         }
 294
 295         sum = ip->ip_sum;
 296         ip->ip_sum = 0;
 297
 298         if (sum != in_cksum(ip, ip->ip_hl * 4))
 299                 return -1;
 300
 301         /* Header overflow check */
 302         mtrace_off = 4 * ip->ip_hl;
 303         if (mtrace_off > MTRACE_BUF_LEN)
 304                 return -1;
 305
 306         /* Underflow/overflow check */
 307         ip_len = ntohs(ip->ip_len);
 308         if (ip_len < mtrace_off || ip_len < MTRACE_HDR_SIZE
 309             || ip_len > MTRACE_BUF_LEN)
 310                 return -1;
 311
 312         mtrace_len = ip_len - mtrace_off;
 313         mtrace = (struct igmp_mtrace *)(mtrace_buf + mtrace_off);
 314
 315         sum = mtrace->checksum;
 316         mtrace->checksum = 0;
 317         if (sum != in_cksum(mtrace, mtrace_len)) {
 318                 fprintf(stderr, "mtrace checksum wrong\n");
 319                 return -1;
 320         }
 321
 322         if (mtrace->type != PIM_IGMP_MTRACE_RESPONSE)
 323                 return -1;
 324
 325
 326         responses = mtrace_len - sizeof(struct igmp_mtrace);
 327         responses /= sizeof(struct igmp_mtrace_rsp);
 328
 329         if (responses > MTRACE_MAX_HOPS) {
 330                 fprintf(stderr, "mtrace too large\n");
 331                 return -1;
 332         }
 333
 334         if (hops)
 335                 *hops = responses;
 336
 337         if (mtracer)
 338                 memcpy(mtracer, mtrace, mtrace_len);
 339
 340         return 0;
 341 }
 342
 343 static int wait_for_response(int fd, int *hops, struct igmp_mtrace *mtrace,
 344                              long *ret_msec)
 345 {
 346         fd_set readfds;
 347         struct timeval timeout;
 348         int ret;
 349         long msec, rmsec, tmsec;
 350
 351         FD_ZERO(&readfds);
 352         FD_SET(fd, &readfds);
 353
 354         memset(&timeout, 0, sizeof(timeout));
 355
 356         timeout.tv_sec = MTRACE_TIMEOUT;
 357
 358         tmsec = timeout.tv_sec * 1000 + timeout.tv_usec / 1000;
 359         do {
 360                 ret = select(fd + 1, &readfds, NULL, NULL, &timeout);
 361                 if (ret <= 0)
 362                         return ret;
 363                 rmsec = timeout.tv_sec * 1000 + timeout.tv_usec / 1000;
 364                 msec = tmsec - rmsec;
 365         } while (recv_response(fd, hops, mtrace) != 0);
 366
 367         if (ret_msec)
 368                 *ret_msec = msec;
 369
 370         return ret;
 371 }
 372
 373 static bool check_end(struct igmp_mtrace *mtrace, int hops)
 374 {
 375         return mtrace->src_addr.s_addr == mtrace->rsp[hops - 1].prev_hop.s_addr;
 376 }
 377
 378 int main(int argc, char *const argv[])
 379 {
 380         struct in_addr mc_source;
 381         struct in_addr mc_group;
 382         struct in_addr iface_addr;
 383         struct in_addr gw_addr;
 384         struct in_addr mtrace_addr;
 385         struct igmp_mtrace mtrace;
 386         struct igmp_mtrace *mtracep;
 387         int hops = 255;
 388         int rhops;
 389         int maxhops = 255;
 390         int perhop = 3;
 391         int ifindex;
 392         int unicast = 1;
 393         int ttl = 64;
 394         int fd = -1;
 395         int ret = -1;
 396         int c;
 397         long msec;
 398         int i, j;
 399         char ifname[IF_NAMESIZE];
 400         char mbuf[MTRACE_BUF_LEN];
 401         bool not_group;
 402
 403         mtrace_addr.s_addr = inet_addr("224.0.1.32");
 404
 405         uid_t uid = getuid();
 406
 407         if (uid != 0) {
 408                 printf("must run as root\n");
 409                 exit(EXIT_FAILURE);
 410         }
 411
 412         if (argc <= 0)
 413                 progname = "mtracebis";
 414         else
 415                 progname = argv[0];
 416
 417         if (argc != 2 && argc != 3) {
 418                 usage();
 419                 exit(EXIT_FAILURE);
 420         }
 421
 422         while (1) {
 423                 static struct option long_options[] = {
 424                         {"help", no_argument, 0, 'h'},
 425                         {"version", no_argument, 0, 'v'},
 426                         {0, 0, 0, 0}};
 427                 int option_index = 0;
 428
 429                 c = getopt_long(argc, argv, "vh", long_options, &option_index);
 430
 431                 if (c == -1)
 432                         break;
 433
 434                 switch (c) {
 435                 case 'h':
 436                         usage();
 437                         exit(0);
 438                 case 'v':
 439                         version();
 440                         exit(0);
 441                 default:
 442                         usage();
 443                         exit(EXIT_FAILURE);
 444                 }
 445         }
 446         if (inet_pton(AF_INET, argv[1], &mc_source) != 1) {
 447                 usage();
 448                 fprintf(stderr, "%s: %s is not a valid IPv4 address\n", argv[0],
 449                         argv[1]);
 450                 exit(EXIT_FAILURE);
 451         }
 452
 453         mc_group.s_addr = 0;
 454         not_group = false;
 455
 456         if (argc == 3) {
 457                 if (inet_pton(AF_INET, argv[2], &mc_group) != 1)
 458                         not_group = true;
 459                 if (!not_group && !IPV4_CLASS_DE(ntohl(mc_group.s_addr)))
 460                         not_group = true;
 461         }
 462
 463         if (not_group) {
 464                 usage();
 465                 fprintf(stderr, "%s: %s is not a valid IPv4 group address\n",
 466                         argv[0], argv[2]);
 467                 exit(EXIT_FAILURE);
 468         }
 469
 470         ifindex = routeget(mc_source, &iface_addr, &gw_addr);
 471         if (ifindex < 0) {
 472                 fprintf(stderr, "%s: failed to get route to source %s\n",
 473                         argv[0], argv[1]);
 474                 exit(EXIT_FAILURE);
 475         }
 476
 477         if (if_indextoname(ifindex, ifname) == NULL) {
 478                 fprintf(stderr, "%s: if_indextoname error: %s\n", argv[0],
 479                         strerror(errno));
 480                 exit(EXIT_FAILURE);
 481         }
 482
 483         /* zero mtrace struct */
 484         memset((char *)&mtrace, 0, sizeof(mtrace));
 485
 486         /* set up query */
 487         mtrace.type = PIM_IGMP_MTRACE_QUERY_REQUEST;
 488         mtrace.hops = hops;
 489         mtrace.checksum = 0;
 490         mtrace.grp_addr = mc_group;
 491         mtrace.src_addr = mc_source;
 492         mtrace.dst_addr = iface_addr;
 493         mtrace.rsp_addr = unicast ? iface_addr : mtrace_addr;
 494         mtrace.rsp_ttl = ttl;
 495         mtrace.qry_id = 0xffffff & time(NULL);
 496
 497         mtrace.checksum = in_cksum(&mtrace, sizeof(mtrace));
 498
 499         fd = socket(AF_INET, SOCK_RAW, IPPROTO_IGMP);
 500
 501         if (fd < 1) {
 502                 fprintf(stderr, "%s: socket error: %s\n", argv[0],
 503                         strerror(errno));
 504                 exit(EXIT_FAILURE);
 505         }
 506
 507         ret = setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, ifname,
 508                          strlen(ifname));
 509
 510         if (ret < 0) {
 511                 fprintf(stderr, "%s: setsockopt error: %s\n", argv[0],
 512                         strerror(errno));
 513                 ret = EXIT_FAILURE;
 514                 goto close_fd;
 515         }
 516
 517         print_query(&mtrace);
 518         if (send_query(fd, gw_addr, &mtrace) < 0) {
 519                 fprintf(stderr, "%s: sendto error: %s\n", argv[0],
 520                         strerror(errno));
 521                 ret = EXIT_FAILURE;
 522                 goto close_fd;
 523         }
 524         printf("Querying full reverse path...\n");
 525         mtracep = (struct igmp_mtrace *)mbuf;
 526         ret = wait_for_response(fd, &rhops, mtracep, &msec);
 527         if (ret > 0) {
 528                 print_responses(mtracep, rhops, msec);
 529                 ret = 0;
 530                 goto close_fd;
 531         }
 532         if (ret < 0) {
 533                 fprintf(stderr, "%s: select error: %s\n", argv[0],
 534                         strerror(errno));
 535                 ret = EXIT_FAILURE;
 536                 goto close_fd;
 537         }
 538         printf(" * ");
 539         printf("switching to hop-by-hop:\n");
 540         print_dest(&mtrace);
 541         for (i = 1; i < maxhops; i++) {
 542                 print_line_no(i);
 543                 mtrace.hops = i;
 544                 for (j = 0; j < perhop; j++) {
 545                         mtrace.qry_id++;
 546                         mtrace.checksum = 0;
 547                         mtrace.checksum = in_cksum(&mtrace, sizeof(mtrace));
 548                         if (send_query(fd, gw_addr, &mtrace) < 0) {
 549                                 fprintf(stderr, "%s: sendto error: %s\n",
 550                                         argv[0], strerror(errno));
 551                                 ret = EXIT_FAILURE;
 552                                 goto close_fd;
 553                         }
 554                         ret = wait_for_response(fd, &rhops, mtracep, &msec);
 555                         if (ret > 0) {
 556                                 if (check_end(mtracep, rhops)) {
 557                                         print_rsp(&mtracep->rsp[rhops - 1]);
 558                                         print_summary(mtracep, rhops, msec);
 559                                         ret = 0;
 560                                         goto close_fd;
 561                                 }
 562                                 if (i > rhops) {
 563                                         printf(" * ...giving up.\n");
 564                                         ret = 0;
 565                                         goto close_fd;
 566                                 }
 567                                 print_rsp(&mtracep->rsp[rhops - 1]);
 568                                 break;
 569                         }
 570                         printf(" *");
 571                 }
 572                 if (ret <= 0)
 573                         printf("\n");
 574         }
 575         ret = 0;
 576 close_fd:
 577         close(fd);
 578         exit(ret);
 579 }
 580
 581 #else /* __linux__ */
 582
 583 #include <stdio.h>
 584 #include <stdlib.h>
 585
 586 int main(int argc, char *argv[])
 587 {
 588         printf("%s implemented only for GNU/Linux\n", argv[0]);
 589         exit(0);
 590 }
 591
 592 #endif /* __linux__ */