minix/commands/irdpd/irdpd.c

   1 /*      irdpd 1.10 - Internet router discovery protocol daemon.
   2  *                                                      Author: Kees J. Bot
   3  *                                                              28 May 1994
   4  * Activily solicitate or passively look for routers.
   5  * Based heavily on its forerunners, the irdp_sol and rip2icmp daemons by
   6  * Philip Homburg.
   7  */
   8 #define nil 0
   9 #include <sys/types.h>
  10 #include <errno.h>
  11 #include <fcntl.h>
  12 #include <stddef.h>
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <time.h>
  17 #include <limits.h>
  18 #include <unistd.h>
  19 #include <signal.h>
  20 #include <sys/ioctl.h>
  21 #include <sys/asynchio.h>
  22 #include <net/hton.h>
  23 #include <net/netlib.h>
  24 #include <net/gen/in.h>
  25 #include <net/gen/ip_hdr.h>
  26 #include <net/gen/icmp.h>
  27 #include <net/gen/icmp_hdr.h>
  28 #include <net/gen/ip_io.h>
  29 #include <net/gen/inet.h>
  30 #include <netdb.h>
  31 #include <net/gen/oneCsum.h>
  32 #include <net/gen/socket.h>
  33 #include <net/gen/udp.h>
  34 #include <net/gen/udp_hdr.h>
  35 #include <net/gen/udp_io.h>
  36 #include <arpa/inet.h>
  37
  38 #define MAX_SOLICITATIONS           3   /* # router solicitations. */
  39 #define SOLICITATION_INTERVAL       3   /* Secs between solicitate retries. */
  40 #define DEST_TO               (10*60)   /* 10 minutes */
  41 #define NEW_ROUTE              (5*60)   /* 5 minutes */
  42 #define DANGER                 (2*60)   /* Nearing a advert timeout? */
  43 #define DEAD_TO             (24L*60*60) /* 24 hours */
  44 #define DEAD_PREF           0x80000000L /* From RFC 1256 */
  45 #define MaxAdvertisementInterval (DEST_TO/2)    /* Chosen to jive with RIP */
  46 #define AdvertisementLifetime    DEST_TO
  47 #define PRIO_OFF_DEF            -1024
  48 #define RIP_REPLY                   2
  49
  50 /* It's now or never. */
  51 #define IMMEDIATELY     ((time_t) ((time_t) -1 < 0 ? LONG_MIN : 0))
  52 #define NEVER           ((time_t) ((time_t) -1 < 0 ? LONG_MAX : ULONG_MAX))
  53
  54 #if !__minix_vmd
  55 /* Standard Minix needs to choose between router discovery and RIP info. */
  56 int do_rdisc= 1;
  57 int do_rip= 0;
  58 #else
  59 /* VMD Minix can do both at once. */
  60 #define do_rdisc 1
  61 #define do_rip 1
  62 #endif
  63
  64 int rip_fd;                     /* For incoming RIP packet. */
  65 int irdp_fd;                    /* Receive or transmit IRDP packets. */
  66
  67 char *udp_device;               /* UDP device to use. */
  68 char *ip_device;                /* IP device to use. */
  69
  70 int priority_offset;            /* Offset to make my routes less preferred. */
  71
  72 int bcast= 0;                   /* Broadcast adverts to all. */
  73 int debug= 0;
  74
  75 char rip_buf[8192];             /* Incoming RIP packet buffer. */
  76 char irdp_buf[1024];            /* IRDP buffer. */
  77
  78 typedef struct routeinfo
  79 {
  80         u8_t            command;
  81         u8_t            version;
  82         u16_t           zero1;
  83         struct routedata {
  84                 u16_t   family;
  85                 u16_t   zero2;
  86                 u32_t   ip_addr;
  87                 u32_t   zero3, zero4;
  88                 u32_t   metric;
  89         } data[1];
  90 } routeinfo_t;
  91
  92 typedef struct table
  93 {
  94         ipaddr_t        tab_gw;
  95         i32_t           tab_pref;
  96         time_t          tab_time;
  97 } table_t;
  98
  99 table_t *table;                 /* Collected table of routing info. */
 100 size_t table_size;
 101
 102 int sol_retries= MAX_SOLICITATIONS;
 103 time_t next_sol= IMMEDIATELY;
 104 time_t next_advert= NEVER;
 105 time_t router_advert_valid= IMMEDIATELY;
 106 time_t now;
 107
 108 void report(const char *label)
 109 /* irdpd: /dev/hd0: Device went up in flames */
 110 {
 111         fprintf(stderr, "irdpd: %s: %s\n", label, strerror(errno));
 112 }
 113
 114 void fatal(const char *label)
 115 /* irdpd: /dev/house: Taking this with it */
 116 {
 117         report(label);
 118         exit(1);
 119 }
 120
 121 #if DEBUG
 122 char *addr2name(ipaddr_t host)
 123 /* Translate an IP address to a printable name. */
 124 {
 125         struct hostent *hostent;
 126
 127         hostent= gethostbyaddr((char *) &host, sizeof(host), AF_INET);
 128         return hostent == nil ? inet_ntoa(host) : hostent->h_name;
 129 }
 130 #else
 131 #define addr2name(host) inet_ntoa(*(struct in_addr *)&(host))
 132 #endif
 133
 134 void print_table(void)
 135 /* Show the collected routing table. */
 136 {
 137         int i;
 138         table_t *ptab;
 139         struct tm *tm;
 140
 141         for (i= 0, ptab= table; i < table_size; i++, ptab++) {
 142                 if (ptab->tab_time < now - DEAD_TO) continue;
 143
 144                 tm= localtime(&ptab->tab_time);
 145                 printf("%-40s %6ld %02d:%02d:%02d\n",
 146                         addr2name(ptab->tab_gw),
 147                         (long) ptab->tab_pref,
 148                         tm->tm_hour, tm->tm_min, tm->tm_sec);
 149         }
 150 }
 151
 152 void advertize(ipaddr_t host)
 153 /* Send a router advert to a host. */
 154 {
 155         char *buf, *data;
 156         ip_hdr_t *ip_hdr;
 157         icmp_hdr_t *icmp_hdr;
 158         int i;
 159         table_t *ptab;
 160
 161         buf= malloc(sizeof(*ip_hdr) + offsetof(icmp_hdr_t, ih_dun.uhd_data)
 162                         + table_size * (sizeof(ipaddr_t) + sizeof(u32_t)));
 163         if (buf == nil) fatal("heap error");
 164
 165         ip_hdr= (ip_hdr_t *) buf;
 166         icmp_hdr= (icmp_hdr_t *) (ip_hdr + 1);
 167
 168         ip_hdr->ih_vers_ihl= 0x45;
 169         ip_hdr->ih_dst= host;
 170
 171         icmp_hdr->ih_type= ICMP_TYPE_ROUTER_ADVER;
 172         icmp_hdr->ih_code= 0;
 173         icmp_hdr->ih_hun.ihh_ram.iram_na= 0;
 174         icmp_hdr->ih_hun.ihh_ram.iram_aes= 2;
 175         icmp_hdr->ih_hun.ihh_ram.iram_lt= htons(AdvertisementLifetime);
 176         data= (char *) icmp_hdr->ih_dun.uhd_data;
 177
 178         /* Collect gateway entries from the table. */
 179         for (i= 0, ptab= table; i < table_size; i++, ptab++) {
 180                 if (ptab->tab_time < now - DEAD_TO) continue;
 181
 182                 icmp_hdr->ih_hun.ihh_ram.iram_na++;
 183                 if (ptab->tab_time < now - DEST_TO) ptab->tab_pref= DEAD_PREF;
 184                 * (ipaddr_t *) data= ptab->tab_gw;
 185                 data+= sizeof(ipaddr_t);
 186                 * (i32_t *) data= htonl(ptab->tab_pref);
 187                 data+= sizeof(i32_t);
 188         }
 189         icmp_hdr->ih_chksum= 0;
 190         icmp_hdr->ih_chksum= ~oneC_sum(0, icmp_hdr, data - (char *) icmp_hdr);
 191
 192         if (icmp_hdr->ih_hun.ihh_ram.iram_na > 0) {
 193                 /* Send routing info. */
 194
 195                 if (debug) {
 196                         printf("Routing table send to %s:\n", addr2name(host));
 197                         print_table();
 198                 }
 199
 200                 if (write(irdp_fd, buf, data - buf) < 0) {
 201                         (errno == EIO ? fatal : report)(ip_device);
 202                 }
 203         }
 204         free(buf);
 205 }
 206
 207 void time_functions(void)
 208 /* Perform time dependend functions: router solicitation, router advert. */
 209 {
 210         if (now >= next_sol) {
 211                 char buf[sizeof(ip_hdr_t) + 8];
 212                 ip_hdr_t *ip_hdr;
 213                 icmp_hdr_t *icmp_hdr;
 214
 215                 if (sol_retries == 0) {
 216                         /* Stop soliciting. */
 217                         next_sol= NEVER;
 218 #if !__minix_vmd
 219                         /* Switch to RIP if no router responded. */
 220                         if (table_size == 0) {
 221                                 do_rip= 1;
 222                                 do_rdisc= 0;
 223                         }
 224 #endif
 225                         return;
 226                 }
 227
 228                 /* Broadcast a router solicitation to find a router. */
 229                 ip_hdr= (ip_hdr_t *) buf;
 230                 icmp_hdr= (icmp_hdr_t *) (ip_hdr + 1);
 231
 232                 ip_hdr->ih_vers_ihl= 0x45;
 233                 ip_hdr->ih_dst= htonl(0xFFFFFFFFL);
 234                 icmp_hdr->ih_type= ICMP_TYPE_ROUTE_SOL;
 235                 icmp_hdr->ih_code= 0;
 236                 icmp_hdr->ih_chksum= 0;
 237                 icmp_hdr->ih_hun.ihh_unused= 0;
 238                 icmp_hdr->ih_chksum= ~oneC_sum(0, icmp_hdr, 8);
 239
 240                 if (debug) printf("Broadcasting router solicitation\n");
 241
 242                 if (write(irdp_fd, buf, sizeof(buf)) < 0)
 243                         fatal("sending router solicitation failed");
 244
 245                 /* Schedule the next packet. */
 246                 next_sol= now + SOLICITATION_INTERVAL;
 247
 248                 sol_retries--;
 249         }
 250
 251         if (now >= next_advert) {
 252                 /* Advertize routes to the local host (normally), or
 253                  * broadcast them (to keep bad hosts up.)
 254                  */
 255
 256                 advertize(bcast ? htonl(0xFFFFFFFFL) : htonl(0x7F000001L));
 257                 next_advert= now + MaxAdvertisementInterval;
 258 #if !__minix_vmd
 259                 /* Make sure we are listening to RIP now. */
 260                 do_rip= 1;
 261                 do_rdisc= 0;
 262 #endif
 263         }
 264 }
 265
 266 void add_gateway(ipaddr_t host, i32_t pref)
 267 /* Add a router with given address and preference to the routing table. */
 268 {
 269         table_t *oldest, *ptab;
 270         int i;
 271
 272         /* Look for the host, or select the oldest entry. */
 273         oldest= nil;
 274         for (i= 0, ptab= table; i < table_size; i++, ptab++) {
 275                 if (ptab->tab_gw == host) break;
 276
 277                 if (oldest == nil || ptab->tab_time < oldest->tab_time)
 278                         oldest= ptab;
 279         }
 280
 281         /* Don't evict the oldest if it is still valid. */
 282         if (oldest != nil && oldest->tab_time >= now - DEST_TO) oldest= nil;
 283
 284         /* Expand the table? */
 285         if (i == table_size && oldest == nil) {
 286                 table_size++;
 287                 table= realloc(table, table_size * sizeof(*table));
 288                 if (table == nil) fatal("heap error");
 289                 oldest= &table[table_size - 1];
 290         }
 291
 292         if (oldest != nil) {
 293                 ptab= oldest;
 294                 ptab->tab_gw= host;
 295                 ptab->tab_pref= DEAD_PREF;
 296         }
 297
 298         /* Replace an entry if the new one looks more promising. */
 299         if (pref >= ptab->tab_pref || ptab->tab_time <= now - NEW_ROUTE) {
 300                 ptab->tab_pref= pref;
 301                 ptab->tab_time= now;
 302         }
 303 }
 304
 305 void rip_incoming(ssize_t n)
 306 /* Use a RIP packet to add to the router table.  (RIP packets are really for
 307  * between routers, but often it is the only information around.)
 308  */
 309 {
 310         udp_io_hdr_t *udp_io_hdr;
 311         u32_t default_dist;
 312         i32_t pref;
 313         routeinfo_t *routeinfo;
 314         struct routedata *data, *end;
 315
 316         /* We don't care about RIP packets when there are router adverts. */
 317         if (now + MaxAdvertisementInterval < router_advert_valid) return;
 318
 319         udp_io_hdr= (udp_io_hdr_t *) rip_buf;
 320         if (udp_io_hdr->uih_data_len != n - sizeof(*udp_io_hdr)) {
 321                 if (debug) printf("Bad sized route packet (discarded)\n");
 322                 return;
 323         }
 324         routeinfo= (routeinfo_t *) (rip_buf + sizeof(*udp_io_hdr)
 325                         + udp_io_hdr->uih_ip_opt_len);
 326
 327         if (routeinfo->command != RIP_REPLY) {
 328                 if (debug) {
 329                         printf("RIP-%d packet command %d ignored\n",
 330                                 routeinfo->version, routeinfo->command);
 331                 }
 332                 return;
 333         }
 334
 335         /* Look for a default route, the route to the gateway. */
 336         end= (struct routedata *) (rip_buf + n);
 337         default_dist= (u32_t) -1;
 338         for (data= routeinfo->data; data < end; data++) {
 339                 if (ntohs(data->family) != AF_INET || data->ip_addr != 0)
 340                         continue;
 341                 default_dist= ntohl(data->metric);
 342                 if (default_dist >= 256) {
 343                         if (debug) {
 344                                 printf("Strange metric %lu\n",
 345                                         (unsigned long) default_dist);
 346                         }
 347                 }
 348         }
 349         pref= default_dist >= 256 ? 1 : 512 - default_dist;
 350         pref+= priority_offset;
 351
 352         /* Add the gateway to the table with the calculated preference. */
 353         add_gateway(udp_io_hdr->uih_src_addr, pref);
 354
 355         if (debug) {
 356                 printf("Routing table after RIP-%d packet from %s:\n",
 357                         routeinfo->version,
 358                         addr2name(udp_io_hdr->uih_src_addr));
 359                 print_table();
 360         }
 361
 362         /* Start advertizing. */
 363         if (next_advert == NEVER) next_advert= IMMEDIATELY;
 364 }
 365
 366 void irdp_incoming(ssize_t n)
 367 /* Look for router solicitations and router advertisements.  The solicitations
 368  * are probably from other irdpd daemons, we answer them if we do not expect
 369  * a real router to answer.  The advertisements cause this daemon to shut up.
 370  */
 371 {
 372         ip_hdr_t *ip_hdr;
 373         icmp_hdr_t *icmp_hdr;
 374         int ip_hdr_len;
 375         char *data;
 376         int i;
 377         int router;
 378         ipaddr_t addr;
 379         i32_t pref;
 380         time_t valid;
 381
 382         ip_hdr= (ip_hdr_t *) irdp_buf;
 383         ip_hdr_len= (ip_hdr->ih_vers_ihl & IH_IHL_MASK) << 2;
 384         if (n < ip_hdr_len + 8) {
 385                 if (debug) printf("Bad sized ICMP (discarded)\n");
 386                 return;
 387         }
 388
 389         icmp_hdr= (icmp_hdr_t *)(irdp_buf + ip_hdr_len);
 390
 391         /* Did I send this myself? */
 392         if (ip_hdr->ih_src == ip_hdr->ih_dst) return;
 393         if ((htonl(ip_hdr->ih_src) & 0xFF000000L) == 0x7F000000L) return;
 394
 395         if (icmp_hdr->ih_type != ICMP_TYPE_ROUTER_ADVER) return;
 396
 397         /* Incoming router advertisement, the kind of packet the TCP/IP task
 398          * is very happy with.  No need to solicit further.
 399          */
 400         sol_retries= 0;
 401
 402         /* Add router info to our table.  Also see if the packet really came
 403          * from a router.  If so then we can go dormant for the lifetime of
 404          * the ICMP.
 405          */
 406         router= 0;
 407         data= (char *) icmp_hdr->ih_dun.uhd_data;
 408         for (i= 0; i < icmp_hdr->ih_hun.ihh_ram.iram_na; i++) {
 409                 addr= * (ipaddr_t *) data;
 410                 data+= sizeof(ipaddr_t);
 411                 pref= htonl(* (i32_t *) data);
 412                 data+= sizeof(i32_t);
 413
 414                 if (addr == ip_hdr->ih_src) {
 415                         /* The sender is in the routing table! */
 416                         router= 1;
 417                 }
 418                 add_gateway(addr, pref);
 419         }
 420
 421         valid= now + ntohs(icmp_hdr->ih_hun.ihh_ram.iram_lt);
 422         if (router) router_advert_valid= valid;
 423
 424         /* Restart advertizing close to the timeout of the advert.  (No more
 425          * irdpd adverts if the router stays alive.)
 426          */
 427         if (router || next_advert > valid - DANGER)
 428                 next_advert= valid - DANGER;
 429
 430         if (debug) {
 431                 printf("Routing table after advert received from %s:\n",
 432                         addr2name(ip_hdr->ih_src));
 433                 print_table();
 434                 if (router) {
 435                         struct tm *tm= localtime(&router_advert_valid);
 436                         printf(
 437                         "This router advert is valid until %02d:%02d:%02d\n",
 438                                 tm->tm_hour, tm->tm_min, tm->tm_sec);
 439                 }
 440         }
 441 }
 442
 443 void sig_handler(int sig)
 444 /* A signal changes the debug level. */
 445 {
 446         switch (sig) {
 447         case SIGUSR1:   debug++;                break;
 448         case SIGUSR2:   debug= 0;               break;
 449         }
 450 }
 451
 452 void usage(void)
 453 {
 454         fprintf(stderr,
 455 "Usage: irdpd [-bd] [-U udp-device] [-I ip-device] [-o priority-offset]\n");
 456         exit(1);
 457 }
 458
 459 int main(int argc, char **argv)
 460 {
 461         int i;
 462         struct servent *service;
 463         udpport_t route_port;
 464         nwio_udpopt_t udpopt;
 465         nwio_ipopt_t ipopt;
 466         asynchio_t asyn;
 467         time_t timeout;
 468         struct timeval tv;
 469         struct sigaction sa;
 470         char *offset_arg, *offset_end;
 471         long arg;
 472
 473         udp_device= ip_device= nil;
 474         offset_arg= nil;
 475
 476         for (i = 1; i < argc && argv[i][0] == '-'; i++) {
 477                 char *p= argv[i] + 1;
 478
 479                 if (p[0] == '-' && p[1] == 0) { i++; break; }
 480
 481                 while (*p != 0) {
 482                         switch (*p++) {
 483                         case 'U':
 484                                 if (udp_device != nil) usage();
 485                                 if (*p == 0) {
 486                                         if (++i == argc) usage();
 487                                         p= argv[i];
 488                                 }
 489                                 udp_device= p;
 490                                 p= "";
 491                                 break;
 492                         case 'I':
 493                                 if (ip_device != nil) usage();
 494                                 if (*p == 0) {
 495                                         if (++i == argc) usage();
 496                                         p= argv[i];
 497                                 }
 498                                 ip_device= p;
 499                                 p= "";
 500                                 break;
 501                         case 'o':
 502                                 if (offset_arg != nil) usage();
 503                                 if (*p == 0) {
 504                                         if (++i == argc) usage();
 505                                         p= argv[i];
 506                                 }
 507                                 offset_arg= p;
 508                                 p= "";
 509                                 break;
 510                         case 'b':
 511                                 bcast= 1;
 512                                 break;
 513                         case 's':
 514                                 /*obsolete*/
 515                                 break;
 516                         case 'd':
 517                                 debug= 1;
 518                                 break;
 519                         default:
 520                                 usage();
 521                         }
 522                 }
 523         }
 524         if (i != argc) usage();
 525
 526         /* Debug level signals. */
 527         sa.sa_handler= sig_handler;
 528         sigemptyset(&sa.sa_mask);
 529         sa.sa_flags= 0;
 530         sigaction(SIGUSR1, &sa, nil);
 531         sigaction(SIGUSR2, &sa, nil);
 532
 533         if (udp_device == nil && (udp_device= getenv("UDP_DEVICE")) == nil)
 534                 udp_device= UDP_DEVICE;
 535
 536         if (ip_device == nil && (ip_device= getenv("IP_DEVICE")) == nil)
 537                 ip_device= IP_DEVICE;
 538
 539         if (offset_arg == nil) {
 540                 priority_offset= PRIO_OFF_DEF;
 541         } else {
 542                 arg= strtol(offset_arg, &offset_end, 0);
 543                 if (*offset_end != 0 || (priority_offset= arg) != arg) usage();
 544         }
 545
 546         if ((service= getservbyname("route", "udp")) == nil) {
 547                 fprintf(stderr,
 548         "irdpd: unable to look up the port number for the 'route' service\n");
 549                 exit(1);
 550         }
 551
 552         route_port= (udpport_t) service->s_port;
 553
 554         if ((rip_fd= open(udp_device, O_RDWR)) < 0) fatal(udp_device);
 555
 556         udpopt.nwuo_flags= NWUO_COPY | NWUO_LP_SET | NWUO_DI_LOC
 557                 | NWUO_EN_BROAD | NWUO_RP_SET | NWUO_RA_ANY | NWUO_RWDATALL
 558                 | NWUO_DI_IPOPT;
 559         udpopt.nwuo_locport= route_port;
 560         udpopt.nwuo_remport= route_port;
 561         if (ioctl(rip_fd, NWIOSUDPOPT, &udpopt) < 0)
 562                 fatal("setting UDP options failed");
 563
 564         if ((irdp_fd= open(ip_device, O_RDWR)) < 0) fatal(ip_device);
 565
 566         ipopt.nwio_flags= NWIO_COPY | NWIO_EN_LOC | NWIO_EN_BROAD
 567                         | NWIO_REMANY | NWIO_PROTOSPEC
 568                         | NWIO_HDR_O_SPEC | NWIO_RWDATALL;
 569         ipopt.nwio_tos= 0;
 570         ipopt.nwio_ttl= 1;
 571         ipopt.nwio_df= 0;
 572         ipopt.nwio_hdropt.iho_opt_siz= 0;
 573         ipopt.nwio_rem= htonl(0xFFFFFFFFL);
 574         ipopt.nwio_proto= IPPROTO_ICMP;
 575
 576         if (ioctl(irdp_fd, NWIOSIPOPT, &ipopt) < 0)
 577                 fatal("can't configure ICMP channel");
 578
 579         asyn_init(&asyn);
 580
 581         while (1) {
 582                 ssize_t r;
 583
 584                 if (do_rip) {
 585                         /* Try a RIP read. */
 586                         r= asyn_read(&asyn, rip_fd, rip_buf, sizeof(rip_buf));
 587                         if (r < 0) {
 588                                 if (errno == EIO) fatal(udp_device);
 589                                 if (errno != EINPROGRESS) report(udp_device);
 590                         } else {
 591                                 now= time(nil);
 592                                 rip_incoming(r);
 593                         }
 594                 }
 595
 596                 if (do_rdisc) {
 597                         /* Try an IRDP read. */
 598                         r= asyn_read(&asyn, irdp_fd, irdp_buf,
 599                                                         sizeof(irdp_buf));
 600                         if (r < 0) {
 601                                 if (errno == EIO) fatal(ip_device);
 602                                 if (errno != EINPROGRESS) report(ip_device);
 603                         } else {
 604                                 now= time(nil);
 605                                 irdp_incoming(r);
 606                         }
 607                 }
 608                 fflush(stdout);
 609
 610                 /* Compute the next wakeup call. */
 611                 timeout= next_sol < next_advert ? next_sol : next_advert;
 612
 613                 /* Wait for a RIP or IRDP packet or a timeout. */
 614                 tv.tv_sec= timeout;
 615                 tv.tv_usec= 0;
 616                 if (asyn_wait(&asyn, 0, timeout == NEVER ? nil : &tv) < 0) {
 617                         /* Timeout? */
 618                         if (errno != EINTR && errno != EAGAIN)
 619                                 fatal("asyn_wait()");
 620                         now= time(nil);
 621                         time_functions();
 622                 }
 623         }
 624 }