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