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