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;
  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 = 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 'd':
 116                         daemonize = true;
 117                         break;
 118
 119                 case 'p':
 120                         pidfile = optarg;
 121                         break;
 122
 123                 default:
 124                         help = true;
 125                         break;
 126                 }
 127         }
 128
 129         const char *ifname = argv[optind];
 130
 131         if (help || !ifname)
 132                 return usage();
 133
 134         if ((urandom_fd = open("/dev/urandom", O_CLOEXEC | O_RDONLY)) < 0 ||
 135                         init_dhcpv6(ifname, request_pd) || ra_init(ifname) ||
 136                         script_init(script, ifname)) {
 137                 syslog(LOG_ERR, "failed to initialize: %s", strerror(errno));
 138                 return 3;
 139         }
 140
 141         signal(SIGIO, sighandler);
 142         signal(SIGHUP, sighandler);
 143         signal(SIGINT, sighandler);
 144         signal(SIGCHLD, sighandler);
 145         signal(SIGTERM, sighandler);
 146         signal(SIGUSR1, sighandler);
 147         signal(SIGUSR2, sighandler);
 148
 149         if (daemonize) {
 150                 openlog("odhcp6c", LOG_PID, LOG_DAEMON); // Disable LOG_PERROR
 151                 if (daemon(0, 0)) {
 152                         syslog(LOG_ERR, "Failed to daemonize: %s",
 153                                         strerror(errno));
 154                         return 4;
 155                 }
 156
 157                 char pidbuf[128];
 158                 if (!pidfile) {
 159                         snprintf(pidbuf, sizeof(pidbuf),
 160                                         "/var/run/odhcp6c.%s.pid", ifname);
 161                         pidfile = pidbuf;
 162                 }
 163
 164                 int fd = open(pidfile, O_WRONLY | O_CREAT);
 165                 if (fd >= 0) {
 166                         char buf[8];
 167                         int len = snprintf(buf, sizeof(buf), "%i\n", getpid());
 168                         write(fd, buf, len);
 169                         close(fd);
 170                 }
 171         }
 172
 173         script_call("started");
 174
 175         while (do_signal != SIGTERM) { // Main logic
 176                 odhcp6c_clear_state(STATE_SERVER_ID);
 177                 odhcp6c_clear_state(STATE_SERVER_CAND);
 178                 odhcp6c_clear_state(STATE_IA_PD);
 179                 odhcp6c_clear_state(STATE_SNTP_IP);
 180                 odhcp6c_clear_state(STATE_SNTP_FQDN);
 181                 odhcp6c_clear_state(STATE_SIP_IP);
 182                 odhcp6c_clear_state(STATE_SIP_FQDN);
 183                 dhcpv6_set_ia_na_mode(ia_na_mode);
 184                 bound = false;
 185
 186                 do_signal = 0;
 187                 int res = dhcpv6_request(DHCPV6_MSG_SOLICIT);
 188                 odhcp6c_signal_process();
 189
 190                 if (res < 0) {
 191                         continue; // Might happen if we got a signal
 192                 } else if (res == DHCPV6_STATELESS) { // Stateless mode
 193                         while (do_signal == 0 || do_signal == SIGUSR1) {
 194                                 do_signal = 0;
 195
 196                                 res = dhcpv6_request(DHCPV6_MSG_INFO_REQ);
 197                                 odhcp6c_signal_process();
 198                                 if (do_signal == SIGUSR1)
 199                                         continue;
 200                                 else if (res < 0)
 201                                         break;
 202                                 else if (res > 0)
 203                                         script_call("informed");
 204
 205                                 bound = true;
 206
 207                                 if (dhcpv6_poll_reconfigure() > 0)
 208                                         script_call("informed");
 209                         }
 210
 211                         continue;
 212                 }
 213
 214                 // Stateful mode
 215                 if (dhcpv6_request(DHCPV6_MSG_REQUEST) < 0)
 216                         continue;
 217
 218                 odhcp6c_signal_process();
 219                 script_call("bound");
 220                 bound = true;
 221
 222                 while (do_signal == 0 || do_signal == SIGUSR1) {
 223                         // Renew Cycle
 224                         // Wait for T1 to expire or until we get a reconfigure
 225                         int res = dhcpv6_poll_reconfigure();
 226                         odhcp6c_signal_process();
 227                         if (res >= 0) {
 228                                 if (res > 0)
 229                                         script_call("updated");
 230
 231                                 continue;
 232                         }
 233
 234                         // Handle signal, if necessary
 235                         if (do_signal == SIGUSR1)
 236                                 do_signal = 0; // Acknowledged
 237                         else if (do_signal > 0)
 238                                 break; // Other signal type
 239
 240                         size_t ia_pd_len, ia_na_len, ia_pd_new, ia_na_new;
 241                         odhcp6c_get_state(STATE_IA_PD, &ia_pd_len);
 242                         odhcp6c_get_state(STATE_IA_NA, &ia_na_len);
 243
 244                         // If we have any IAs, send renew, otherwise request
 245                         int r;
 246                         if (ia_pd_len == 0 && ia_na_len == 0)
 247                                 r = dhcpv6_request(DHCPV6_MSG_REQUEST);
 248                         else
 249                                 r = dhcpv6_request(DHCPV6_MSG_RENEW);
 250                         odhcp6c_signal_process();
 251                         if (r > 0) // Publish updates
 252                                 script_call("updated");
 253                         if (r >= 0)
 254                                 continue; // Renew was successful
 255
 256                         odhcp6c_clear_state(STATE_SERVER_ID); // Remove binding
 257
 258                         // If we have IAs, try rebind otherwise restart
 259                         res = dhcpv6_request(DHCPV6_MSG_REBIND);
 260                         odhcp6c_signal_process();
 261
 262                         odhcp6c_get_state(STATE_IA_PD, &ia_pd_new);
 263                         odhcp6c_get_state(STATE_IA_NA, &ia_na_new);
 264                         if (res < 0 || (ia_pd_new == 0 && ia_pd_len) ||
 265                                         (ia_na_new == 0 && ia_na_len))
 266                                 break; // We lost all our IAs, restart
 267                         else if (res > 0)
 268                                 script_call("rebound");
 269                 }
 270
 271
 272                 size_t ia_pd_len, ia_na_len, server_id_len;
 273                 odhcp6c_get_state(STATE_IA_PD, &ia_pd_len);
 274                 odhcp6c_get_state(STATE_IA_NA, &ia_na_len);
 275                 odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 276
 277                 // Add all prefixes to lost prefixes
 278                 bound = false;
 279                 script_call("unbound");
 280
 281                 if (server_id_len > 0 && (ia_pd_len > 0 || ia_na_len > 0))
 282                         dhcpv6_request(DHCPV6_MSG_RELEASE);
 283
 284                 odhcp6c_clear_state(STATE_IA_NA);
 285                 odhcp6c_clear_state(STATE_IA_PD);
 286         }
 287
 288         script_call("stopped");
 289         return 0;
 290 }
 291
 292
 293 static int usage(void)
 294 {
 295         const char buf[] =
 296         "Usage: odhcp6c [options] <interface>\n"
 297         "\nFeature options:\n"
 298         "       -S              Don't allow SLAAC-only (implied by -P)\n"
 299         "       -N <mode>       Mode for requesting addresses [try|force|none]\n"
 300         "       -P <length>     Request IPv6-Prefix (0 = auto)\n"
 301         "       -c <clientid>   Override client-ID (base-16 encoded)\n"
 302         "       -r <options>    Options to be requested (comma-separated)\n"
 303         "       -s <script>     Status update script (/usr/sbin/odhcp6c-update)\n"
 304         "\nInvocation options:\n"
 305         "       -p <pidfile>    Set pidfile (/var/run/6relayd.pid)\n"
 306         "       -d              Daemonize\n"
 307         //"     -v              Increase logging verbosity\n"
 308         "       -h              Show this help\n\n";
 309         write(STDERR_FILENO, buf, sizeof(buf));
 310         return 1;
 311 }
 312
 313
 314 // Don't want to pull-in librt and libpthread just for a monotonic clock...
 315 uint64_t odhcp6c_get_milli_time(void)
 316 {
 317         struct timespec t = {0, 0};
 318         syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &t);
 319         return t.tv_sec * 1000 + t.tv_nsec / 1000000;
 320 }
 321
 322
 323 static uint8_t* odhcp6c_resize_state(enum odhcp6c_state state, ssize_t len)
 324 {
 325         if (len == 0)
 326                 return state_data[state] + state_len[state];
 327         else if (state_len[state] + len > 1024)
 328                 return NULL;
 329
 330         uint8_t *n = realloc(state_data[state], state_len[state] + len);
 331         if (n || state_len[state] + len == 0) {
 332                 state_data[state] = n;
 333                 n += state_len[state];
 334                 state_len[state] += len;
 335         }
 336         return n;
 337 }
 338
 339
 340 bool odhcp6c_signal_process(void)
 341 {
 342         if (do_signal == SIGIO) {
 343                 do_signal = 0;
 344                 bool updated = ra_process();
 345                 updated |= ra_rtnl_process();
 346                 if (updated && (bound || allow_slaac_only)) {
 347                         odhcp6c_expire();
 348                         script_call("ra-updated");
 349                 }
 350         }
 351
 352         return do_signal != 0;
 353 }
 354
 355
 356 void odhcp6c_clear_state(enum odhcp6c_state state)
 357 {
 358         state_len[state] = 0;
 359 }
 360
 361
 362 void odhcp6c_add_state(enum odhcp6c_state state, const void *data, size_t len)
 363 {
 364         uint8_t *n = odhcp6c_resize_state(state, len);
 365         if (n)
 366                 memcpy(n, data, len);
 367 }
 368
 369
 370 size_t odhcp6c_remove_state(enum odhcp6c_state state, size_t offset, size_t len)
 371 {
 372         uint8_t *data = state_data[state];
 373         ssize_t len_after = state_len[state] - (offset + len);
 374         if (len_after < 0)
 375                 return state_len[state];
 376
 377         memmove(data + offset, data + offset + len, len_after);
 378         return state_len[state] -= len;
 379 }
 380
 381
 382 void* odhcp6c_get_state(enum odhcp6c_state state, size_t *len)
 383 {
 384         *len = state_len[state];
 385         return state_data[state];
 386 }
 387
 388
 389 struct odhcp6c_entry* odhcp6c_find_entry(enum odhcp6c_state state, const struct odhcp6c_entry *new)
 390 {
 391         size_t len, cmplen = offsetof(struct odhcp6c_entry, target) + new->length / 8;
 392         struct odhcp6c_entry *start = odhcp6c_get_state(state, &len);
 393         struct odhcp6c_entry *x = NULL;
 394
 395         for (struct odhcp6c_entry *c = start; !x && c < &start[len/sizeof(*c)]; ++c)
 396                 if (!memcmp(c, new, cmplen))
 397                         return c;
 398
 399         return NULL;
 400 }
 401
 402
 403 void odhcp6c_update_entry_safe(enum odhcp6c_state state, struct odhcp6c_entry *new, uint32_t safe)
 404 {
 405         size_t len;
 406         struct odhcp6c_entry *x = odhcp6c_find_entry(state, new);
 407         struct odhcp6c_entry *start = odhcp6c_get_state(state, &len);
 408
 409         if (x && x->valid > new->valid && new->valid < safe)
 410                 new->valid = safe;
 411
 412         if (new->valid > 0) {
 413                 if (x) {
 414                         x->valid = new->valid;
 415                         x->preferred = new->preferred;
 416                 } else {
 417                         odhcp6c_add_state(state, new, sizeof(*new));
 418                 }
 419         } else if (x) {
 420                 odhcp6c_remove_state(state, (x - start) * sizeof(*x), sizeof(*x));
 421         }
 422 }
 423
 424
 425 void odhcp6c_update_entry(enum odhcp6c_state state, struct odhcp6c_entry *new)
 426 {
 427         odhcp6c_update_entry_safe(state, new, 0);
 428 }
 429
 430
 431 static void odhcp6c_expire_list(enum odhcp6c_state state, uint32_t elapsed)
 432 {
 433         size_t len;
 434         struct odhcp6c_entry *start = odhcp6c_get_state(state, &len);
 435         for (struct odhcp6c_entry *c = start; c < &start[len / sizeof(*c)]; ++c) {
 436                 if (c->preferred < elapsed)
 437                         c->preferred = 0;
 438                 else if (c->preferred != UINT32_MAX)
 439                         c->preferred -= elapsed;
 440
 441                 if (c->valid < elapsed)
 442                         c->valid = 0;
 443                 else if (c->valid != UINT32_MAX)
 444                         c->valid -= elapsed;
 445
 446                 if (!c->valid)
 447                         odhcp6c_remove_state(state, (c - start) * sizeof(*c), sizeof(*c));
 448         }
 449 }
 450
 451
 452 void odhcp6c_expire(void)
 453 {
 454         static time_t last_update = 0;
 455         time_t now = odhcp6c_get_milli_time() / 1000;
 456
 457         uint32_t elapsed = now - last_update;
 458         last_update = now;
 459
 460         odhcp6c_expire_list(STATE_RA_PREFIX, elapsed);
 461         odhcp6c_expire_list(STATE_RA_ROUTE, elapsed);
 462         odhcp6c_expire_list(STATE_RA_DNS, elapsed);
 463         odhcp6c_expire_list(STATE_IA_NA, elapsed);
 464         odhcp6c_expire_list(STATE_IA_PD, elapsed);
 465 }
 466
 467
 468 void odhcp6c_random(void *buf, size_t len)
 469 {
 470         read(urandom_fd, buf, len);
 471 }
 472
 473
 474 static void sighandler(int signal)
 475 {
 476         if (signal == SIGCHLD)
 477                 while (waitpid(-1, NULL, WNOHANG) > 0);
 478         else if (signal == SIGUSR1)
 479                 do_signal = SIGUSR1;
 480         else if (signal == SIGUSR2)
 481                 do_signal = SIGUSR2;
 482         else if (signal == SIGIO)
 483                 do_signal = SIGIO;
 484         else
 485                 do_signal = SIGTERM;
 486 }