src/odhcp6c.c

   1 /**
   2  * Copyright (C) 2012 Steven Barth <steven@midlink.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License v2 as published by
   6  * the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  */
  14
  15 #include <time.h>
  16 #include <errno.h>
  17 #include <fcntl.h>
  18 #include <stdio.h>
  19 #include <stdlib.h>
  20 #include <stddef.h>
  21 #include <unistd.h>
  22 #include <syslog.h>
  23 #include <signal.h>
  24 #include <string.h>
  25 #include <stdbool.h>
  26
  27 #include <net/if.h>
  28 #include <sys/wait.h>
  29 #include <sys/syscall.h>
  30
  31 #include "odhcp6c.h"
  32 #include "ra.h"
  33
  34
  35 static void sighandler(int signal);
  36 static int usage(void);
  37
  38
  39 static uint8_t *state_data[_STATE_MAX] = {NULL};
  40 static size_t state_len[_STATE_MAX] = {0};
  41
  42 static volatile int do_signal = 0;
  43 static int urandom_fd = -1;
  44 static bool bound = false, allow_slaac_only = true, release = true;
  45
  46
  47 int main(_unused int argc, char* const argv[])
  48 {
  49         openlog("odhcp6c", LOG_PERROR | LOG_PID, LOG_DAEMON);
  50
  51         // Allocate ressources
  52         const char *pidfile = NULL;
  53         const char *script = "/usr/sbin/odhcp6c-update";
  54         ssize_t l;
  55         uint8_t buf[134];
  56         char *optpos;
  57         uint16_t opttype;
  58         enum odhcp6c_ia_mode ia_na_mode = IA_MODE_TRY;
  59
  60         bool help = false, daemonize = false;
  61         int c, request_pd = 0;
  62         while ((c = getopt(argc, argv, "SN:P:c:r:s:khdp:")) != -1) {
  63                 switch (c) {
  64                 case 'S':
  65                         allow_slaac_only = false;
  66                         break;
  67
  68                 case 'N':
  69                         if (!strcmp(optarg, "force"))
  70                                 ia_na_mode = IA_MODE_FORCE;
  71                         else if (!strcmp(optarg, "none"))
  72                                 ia_na_mode = IA_MODE_NONE;
  73                         else if (!strcmp(optarg, "try"))
  74                                 ia_na_mode = IA_MODE_TRY;
  75                         else
  76                                 help = true;
  77                         break;
  78
  79                 case 'P':
  80                         allow_slaac_only = false;
  81                         request_pd = strtoul(optarg, NULL, 10);
  82                         if (request_pd == 0)
  83                                 request_pd = -1;
  84                         break;
  85
  86                 case 'c':
  87                         l = script_unhexlify(&buf[4], sizeof(buf) - 4, optarg);
  88                         if (l > 0) {
  89                                 buf[0] = 0;
  90                                 buf[1] = DHCPV6_OPT_CLIENTID;
  91                                 buf[2] = 0;
  92                                 buf[4] = l;
  93                                 odhcp6c_add_state(STATE_CLIENT_ID, buf, l + 4);
  94                         } else {
  95                                 help = true;
  96                         }
  97                         break;
  98
  99                 case 'r':
 100                         optpos = optarg;
 101                         while (optpos[0]) {
 102                                 opttype = htons(strtoul(optarg, &optpos, 10));
 103                                 if (optpos == optarg)
 104                                         break;
 105                                 else if (optpos[0])
 106                                         optarg = &optpos[1];
 107                                 odhcp6c_add_state(STATE_ORO, &opttype, 2);
 108                         }
 109                         break;
 110
 111                 case 's':
 112                         script = optarg;
 113                         break;
 114
 115                 case 'k':
 116                         release = false;
 117                         break;
 118
 119                 case 'd':
 120                         daemonize = true;
 121                         break;
 122
 123                 case 'p':
 124                         pidfile = optarg;
 125                         break;
 126
 127                 default:
 128                         help = true;
 129                         break;
 130                 }
 131         }
 132
 133         const char *ifname = argv[optind];
 134
 135         if (help || !ifname)
 136                 return usage();
 137
 138         if ((urandom_fd = open("/dev/urandom", O_CLOEXEC | O_RDONLY)) < 0 ||
 139                         init_dhcpv6(ifname, request_pd) || ra_init(ifname) ||
 140                         script_init(script, ifname)) {
 141                 syslog(LOG_ERR, "failed to initialize: %s", strerror(errno));
 142                 return 3;
 143         }
 144
 145         signal(SIGIO, sighandler);
 146         signal(SIGHUP, sighandler);
 147         signal(SIGINT, sighandler);
 148         signal(SIGCHLD, sighandler);
 149         signal(SIGTERM, sighandler);
 150         signal(SIGUSR1, sighandler);
 151         signal(SIGUSR2, sighandler);
 152
 153         if (daemonize) {
 154                 openlog("odhcp6c", LOG_PID, LOG_DAEMON); // Disable LOG_PERROR
 155                 if (daemon(0, 0)) {
 156                         syslog(LOG_ERR, "Failed to daemonize: %s",
 157                                         strerror(errno));
 158                         return 4;
 159                 }
 160
 161                 char pidbuf[128];
 162                 if (!pidfile) {
 163                         snprintf(pidbuf, sizeof(pidbuf),
 164                                         "/var/run/odhcp6c.%s.pid", ifname);
 165                         pidfile = pidbuf;
 166                 }
 167
 168                 int fd = open(pidfile, O_WRONLY | O_CREAT);
 169                 if (fd >= 0) {
 170                         char buf[8];
 171                         int len = snprintf(buf, sizeof(buf), "%i\n", getpid());
 172                         write(fd, buf, len);
 173                         close(fd);
 174                 }
 175         }
 176
 177         script_call("started");
 178
 179         while (do_signal != SIGTERM) { // Main logic
 180                 odhcp6c_clear_state(STATE_SERVER_ID);
 181                 odhcp6c_clear_state(STATE_SERVER_CAND);
 182                 odhcp6c_clear_state(STATE_IA_PD);
 183                 odhcp6c_clear_state(STATE_SNTP_IP);
 184                 odhcp6c_clear_state(STATE_SNTP_FQDN);
 185                 odhcp6c_clear_state(STATE_SIP_IP);
 186                 odhcp6c_clear_state(STATE_SIP_FQDN);
 187                 dhcpv6_set_ia_na_mode(ia_na_mode);
 188                 bound = false;
 189
 190                 syslog(LOG_NOTICE, "(re)starting transaction on %s", ifname);
 191
 192                 do_signal = 0;
 193                 int res = dhcpv6_request(DHCPV6_MSG_SOLICIT);
 194                 odhcp6c_signal_process();
 195
 196                 if (res < 0) {
 197                         continue; // Might happen if we got a signal
 198                 } else if (res == DHCPV6_STATELESS) { // Stateless mode
 199                         while (do_signal == 0 || do_signal == SIGUSR1) {
 200                                 do_signal = 0;
 201
 202                                 res = dhcpv6_request(DHCPV6_MSG_INFO_REQ);
 203                                 odhcp6c_signal_process();
 204                                 if (do_signal == SIGUSR1)
 205                                         continue;
 206                                 else if (res < 0)
 207                                         break;
 208                                 else if (res > 0)
 209                                         script_call("informed");
 210
 211                                 bound = true;
 212                                 syslog(LOG_NOTICE, "entering stateless-mode on %s", ifname);
 213
 214                                 if (dhcpv6_poll_reconfigure() > 0)
 215                                         script_call("informed");
 216                         }
 217
 218                         continue;
 219                 }
 220
 221                 // Stateful mode
 222                 if (dhcpv6_request(DHCPV6_MSG_REQUEST) < 0)
 223                         continue;
 224
 225                 odhcp6c_signal_process();
 226                 script_call("bound");
 227                 bound = true;
 228                 syslog(LOG_NOTICE, "entering stateful-mode on %s", ifname);
 229
 230                 while (do_signal == 0 || do_signal == SIGUSR1) {
 231                         // Renew Cycle
 232                         // Wait for T1 to expire or until we get a reconfigure
 233                         int res = dhcpv6_poll_reconfigure();
 234                         odhcp6c_signal_process();
 235                         if (res >= 0) {
 236                                 if (res > 0)
 237                                         script_call("updated");
 238
 239                                 continue;
 240                         }
 241
 242                         // Handle signal, if necessary
 243                         if (do_signal == SIGUSR1)
 244                                 do_signal = 0; // Acknowledged
 245                         else if (do_signal > 0)
 246                                 break; // Other signal type
 247
 248                         size_t ia_pd_len, ia_na_len, ia_pd_new, ia_na_new;
 249                         odhcp6c_get_state(STATE_IA_PD, &ia_pd_len);
 250                         odhcp6c_get_state(STATE_IA_NA, &ia_na_len);
 251
 252                         // If we have any IAs, send renew, otherwise request
 253                         int r;
 254                         if (ia_pd_len == 0 && ia_na_len == 0)
 255                                 r = dhcpv6_request(DHCPV6_MSG_REQUEST);
 256                         else
 257                                 r = dhcpv6_request(DHCPV6_MSG_RENEW);
 258                         odhcp6c_signal_process();
 259                         if (r > 0) // Publish updates
 260                                 script_call("updated");
 261                         if (r >= 0)
 262                                 continue; // Renew was successful
 263
 264                         odhcp6c_clear_state(STATE_SERVER_ID); // Remove binding
 265
 266                         // If we have IAs, try rebind otherwise restart
 267                         res = dhcpv6_request(DHCPV6_MSG_REBIND);
 268                         odhcp6c_signal_process();
 269
 270                         odhcp6c_get_state(STATE_IA_PD, &ia_pd_new);
 271                         odhcp6c_get_state(STATE_IA_NA, &ia_na_new);
 272                         if (res < 0 || (ia_pd_new == 0 && ia_pd_len) ||
 273                                         (ia_na_new == 0 && ia_na_len))
 274                                 break; // We lost all our IAs, restart
 275                         else if (res > 0)
 276                                 script_call("rebound");
 277                 }
 278
 279
 280                 size_t ia_pd_len, ia_na_len, server_id_len;
 281                 odhcp6c_get_state(STATE_IA_PD, &ia_pd_len);
 282                 odhcp6c_get_state(STATE_IA_NA, &ia_na_len);
 283                 odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 284
 285                 // Add all prefixes to lost prefixes
 286                 bound = false;
 287                 script_call("unbound");
 288
 289                 if (server_id_len > 0 && (ia_pd_len > 0 || ia_na_len > 0) && release)
 290                         dhcpv6_request(DHCPV6_MSG_RELEASE);
 291
 292                 odhcp6c_clear_state(STATE_IA_NA);
 293                 odhcp6c_clear_state(STATE_IA_PD);
 294         }
 295
 296         script_call("stopped");
 297         return 0;
 298 }
 299
 300
 301 static int usage(void)
 302 {
 303         const char buf[] =
 304         "Usage: odhcp6c [options] <interface>\n"
 305         "\nFeature options:\n"
 306         "       -S              Don't allow SLAAC-only (implied by -P)\n"
 307         "       -N <mode>       Mode for requesting addresses [try|force|none]\n"
 308         "       -P <length>     Request IPv6-Prefix (0 = auto)\n"
 309         "       -c <clientid>   Override client-ID (base-16 encoded)\n"
 310         "       -r <options>    Options to be requested (comma-separated)\n"
 311         "       -s <script>     Status update script (/usr/sbin/odhcp6c-update)\n"
 312         "       -k              Don't send a RELEASE when stopping\n"
 313         "\nInvocation options:\n"
 314         "       -p <pidfile>    Set pidfile (/var/run/6relayd.pid)\n"
 315         "       -d              Daemonize\n"
 316         //"     -v              Increase logging verbosity\n"
 317         "       -h              Show this help\n\n";
 318         write(STDERR_FILENO, buf, sizeof(buf));
 319         return 1;
 320 }
 321
 322
 323 // Don't want to pull-in librt and libpthread just for a monotonic clock...
 324 uint64_t odhcp6c_get_milli_time(void)
 325 {
 326         struct timespec t = {0, 0};
 327         syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &t);
 328         return t.tv_sec * 1000 + t.tv_nsec / 1000000;
 329 }
 330
 331
 332 static uint8_t* odhcp6c_resize_state(enum odhcp6c_state state, ssize_t len)
 333 {
 334         if (len == 0)
 335                 return state_data[state] + state_len[state];
 336         else if (state_len[state] + len > 1024)
 337                 return NULL;
 338
 339         uint8_t *n = realloc(state_data[state], state_len[state] + len);
 340         if (n || state_len[state] + len == 0) {
 341                 state_data[state] = n;
 342                 n += state_len[state];
 343                 state_len[state] += len;
 344         }
 345         return n;
 346 }
 347
 348
 349 bool odhcp6c_signal_process(void)
 350 {
 351         if (do_signal == SIGIO) {
 352                 do_signal = 0;
 353                 bool updated = ra_process();
 354                 updated |= ra_rtnl_process();
 355                 if (updated && (bound || allow_slaac_only)) {
 356                         odhcp6c_expire();
 357                         script_call("ra-updated");
 358                 }
 359         }
 360
 361         return do_signal != 0;
 362 }
 363
 364
 365 void odhcp6c_clear_state(enum odhcp6c_state state)
 366 {
 367         state_len[state] = 0;
 368 }
 369
 370
 371 void odhcp6c_add_state(enum odhcp6c_state state, const void *data, size_t len)
 372 {
 373         uint8_t *n = odhcp6c_resize_state(state, len);
 374         if (n)
 375                 memcpy(n, data, len);
 376 }
 377
 378
 379 size_t odhcp6c_remove_state(enum odhcp6c_state state, size_t offset, size_t len)
 380 {
 381         uint8_t *data = state_data[state];
 382         ssize_t len_after = state_len[state] - (offset + len);
 383         if (len_after < 0)
 384                 return state_len[state];
 385
 386         memmove(data + offset, data + offset + len, len_after);
 387         return state_len[state] -= len;
 388 }
 389
 390
 391 void* odhcp6c_get_state(enum odhcp6c_state state, size_t *len)
 392 {
 393         *len = state_len[state];
 394         return state_data[state];
 395 }
 396
 397
 398 struct odhcp6c_entry* odhcp6c_find_entry(enum odhcp6c_state state, const struct odhcp6c_entry *new)
 399 {
 400         size_t len, cmplen = offsetof(struct odhcp6c_entry, target) + new->length / 8;
 401         struct odhcp6c_entry *start = odhcp6c_get_state(state, &len);
 402         struct odhcp6c_entry *x = NULL;
 403
 404         for (struct odhcp6c_entry *c = start; !x && c < &start[len/sizeof(*c)]; ++c)
 405                 if (!memcmp(c, new, cmplen))
 406                         return c;
 407
 408         return NULL;
 409 }
 410
 411
 412 void odhcp6c_update_entry_safe(enum odhcp6c_state state, struct odhcp6c_entry *new, uint32_t safe)
 413 {
 414         size_t len;
 415         struct odhcp6c_entry *x = odhcp6c_find_entry(state, new);
 416         struct odhcp6c_entry *start = odhcp6c_get_state(state, &len);
 417
 418         if (x && x->valid > new->valid && new->valid < safe)
 419                 new->valid = safe;
 420
 421         if (new->valid > 0) {
 422                 if (x) {
 423                         x->valid = new->valid;
 424                         x->preferred = new->preferred;
 425                 } else {
 426                         odhcp6c_add_state(state, new, sizeof(*new));
 427                 }
 428         } else if (x) {
 429                 odhcp6c_remove_state(state, (x - start) * sizeof(*x), sizeof(*x));
 430         }
 431 }
 432
 433
 434 void odhcp6c_update_entry(enum odhcp6c_state state, struct odhcp6c_entry *new)
 435 {
 436         odhcp6c_update_entry_safe(state, new, 0);
 437 }
 438
 439
 440 static void odhcp6c_expire_list(enum odhcp6c_state state, uint32_t elapsed)
 441 {
 442         size_t len;
 443         struct odhcp6c_entry *start = odhcp6c_get_state(state, &len);
 444         for (struct odhcp6c_entry *c = start; c < &start[len / sizeof(*c)]; ++c) {
 445                 if (c->preferred < elapsed)
 446                         c->preferred = 0;
 447                 else if (c->preferred != UINT32_MAX)
 448                         c->preferred -= elapsed;
 449
 450                 if (c->valid < elapsed)
 451                         c->valid = 0;
 452                 else if (c->valid != UINT32_MAX)
 453                         c->valid -= elapsed;
 454
 455                 if (!c->valid)
 456                         odhcp6c_remove_state(state, (c - start) * sizeof(*c), sizeof(*c));
 457         }
 458 }
 459
 460
 461 void odhcp6c_expire(void)
 462 {
 463         static time_t last_update = 0;
 464         time_t now = odhcp6c_get_milli_time() / 1000;
 465
 466         uint32_t elapsed = now - last_update;
 467         last_update = now;
 468
 469         odhcp6c_expire_list(STATE_RA_PREFIX, elapsed);
 470         odhcp6c_expire_list(STATE_RA_ROUTE, elapsed);
 471         odhcp6c_expire_list(STATE_RA_DNS, elapsed);
 472         odhcp6c_expire_list(STATE_IA_NA, elapsed);
 473         odhcp6c_expire_list(STATE_IA_PD, elapsed);
 474 }
 475
 476
 477 void odhcp6c_random(void *buf, size_t len)
 478 {
 479         read(urandom_fd, buf, len);
 480 }
 481
 482
 483 static void sighandler(int signal)
 484 {
 485         if (signal == SIGCHLD)
 486                 while (waitpid(-1, NULL, WNOHANG) > 0);
 487         else if (signal == SIGUSR1)
 488                 do_signal = SIGUSR1;
 489         else if (signal == SIGUSR2)
 490                 do_signal = SIGUSR2;
 491         else if (signal == SIGIO)
 492                 do_signal = SIGIO;
 493         else
 494                 do_signal = SIGTERM;
 495 }