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         // Allocate ressources
  50         const char *pidfile = NULL;
  51         const char *script = "/usr/sbin/odhcp6c-update";
  52         ssize_t l;
  53         uint8_t buf[134];
  54         char *optpos;
  55         uint16_t opttype;
  56         enum odhcp6c_ia_mode ia_na_mode = IA_MODE_TRY;
  57
  58         bool help = false, daemonize = false;
  59         int logopt = LOG_PID;
  60         int c, request_pd = 0;
  61         while ((c = getopt(argc, argv, "SN:P:c:r:s:khedp:")) != -1) {
  62                 switch (c) {
  63                 case 'S':
  64                         allow_slaac_only = false;
  65                         break;
  66
  67                 case 'N':
  68                         if (!strcmp(optarg, "force"))
  69                                 ia_na_mode = IA_MODE_FORCE;
  70                         else if (!strcmp(optarg, "none"))
  71                                 ia_na_mode = IA_MODE_NONE;
  72                         else if (!strcmp(optarg, "try"))
  73                                 ia_na_mode = IA_MODE_TRY;
  74                         else
  75                                 help = true;
  76                         break;
  77
  78                 case 'P':
  79                         allow_slaac_only = false;
  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[3] = 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 'k':
 115                         release = false;
 116                         break;
 117
 118                 case 'e':
 119                         logopt |= LOG_PERROR;
 120                         break;
 121
 122                 case 'd':
 123                         daemonize = true;
 124                         break;
 125
 126                 case 'p':
 127                         pidfile = optarg;
 128                         break;
 129
 130                 default:
 131                         help = true;
 132                         break;
 133                 }
 134         }
 135
 136         openlog("odhcp6c", logopt, LOG_DAEMON);
 137         const char *ifname = argv[optind];
 138
 139         if (help || !ifname)
 140                 return usage();
 141
 142         signal(SIGIO, sighandler);
 143         signal(SIGHUP, sighandler);
 144         signal(SIGINT, sighandler);
 145         signal(SIGCHLD, sighandler);
 146         signal(SIGTERM, sighandler);
 147         signal(SIGUSR1, sighandler);
 148         signal(SIGUSR2, sighandler);
 149
 150         if ((urandom_fd = open("/dev/urandom", O_CLOEXEC | O_RDONLY)) < 0 ||
 151                         init_dhcpv6(ifname, request_pd) || ra_init(ifname) ||
 152                         script_init(script, ifname)) {
 153                 syslog(LOG_ERR, "failed to initialize: %s", strerror(errno));
 154                 return 3;
 155         }
 156
 157         if (daemonize) {
 158                 openlog("odhcp6c", LOG_PID, LOG_DAEMON); // Disable LOG_PERROR
 159                 if (daemon(0, 0)) {
 160                         syslog(LOG_ERR, "Failed to daemonize: %s",
 161                                         strerror(errno));
 162                         return 4;
 163                 }
 164
 165                 char pidbuf[128];
 166                 if (!pidfile) {
 167                         snprintf(pidbuf, sizeof(pidbuf),
 168                                         "/var/run/odhcp6c.%s.pid", ifname);
 169                         pidfile = pidbuf;
 170                 }
 171
 172                 int fd = open(pidfile, O_WRONLY | O_CREAT);
 173                 if (fd >= 0) {
 174                         char buf[8];
 175                         int len = snprintf(buf, sizeof(buf), "%i\n", getpid());
 176                         write(fd, buf, len);
 177                         close(fd);
 178                 }
 179         }
 180
 181         script_call("started");
 182
 183         while (do_signal != SIGTERM) { // Main logic
 184                 odhcp6c_clear_state(STATE_SERVER_ID);
 185                 odhcp6c_clear_state(STATE_SERVER_CAND);
 186                 odhcp6c_clear_state(STATE_IA_PD);
 187                 odhcp6c_clear_state(STATE_SNTP_IP);
 188                 odhcp6c_clear_state(STATE_SNTP_FQDN);
 189                 odhcp6c_clear_state(STATE_SIP_IP);
 190                 odhcp6c_clear_state(STATE_SIP_FQDN);
 191                 dhcpv6_set_ia_na_mode(ia_na_mode);
 192                 bound = false;
 193
 194                 syslog(LOG_NOTICE, "(re)starting transaction on %s", ifname);
 195
 196                 do_signal = 0;
 197                 int res = dhcpv6_request(DHCPV6_MSG_SOLICIT);
 198                 odhcp6c_signal_process();
 199
 200                 if (res < 0) {
 201                         continue; // Might happen if we got a signal
 202                 } else if (res == DHCPV6_STATELESS) { // Stateless mode
 203                         while (do_signal == 0 || do_signal == SIGUSR1) {
 204                                 do_signal = 0;
 205
 206                                 res = dhcpv6_request(DHCPV6_MSG_INFO_REQ);
 207                                 odhcp6c_signal_process();
 208                                 if (do_signal == SIGUSR1)
 209                                         continue;
 210                                 else if (res < 0)
 211                                         break;
 212                                 else if (res > 0)
 213                                         script_call("informed");
 214
 215                                 bound = true;
 216                                 syslog(LOG_NOTICE, "entering stateless-mode on %s", ifname);
 217
 218                                 if (dhcpv6_poll_reconfigure() > 0)
 219                                         script_call("informed");
 220                         }
 221
 222                         continue;
 223                 }
 224
 225                 // Stateful mode
 226                 if (dhcpv6_request(DHCPV6_MSG_REQUEST) < 0)
 227                         continue;
 228
 229                 odhcp6c_signal_process();
 230                 script_call("bound");
 231                 bound = true;
 232                 syslog(LOG_NOTICE, "entering stateful-mode on %s", ifname);
 233
 234                 while (do_signal == 0 || do_signal == SIGUSR1) {
 235                         // Renew Cycle
 236                         // Wait for T1 to expire or until we get a reconfigure
 237                         int res = dhcpv6_poll_reconfigure();
 238                         odhcp6c_signal_process();
 239                         if (res >= 0) {
 240                                 if (res > 0)
 241                                         script_call("updated");
 242
 243                                 continue;
 244                         }
 245
 246                         // Handle signal, if necessary
 247                         if (do_signal == SIGUSR1)
 248                                 do_signal = 0; // Acknowledged
 249                         else if (do_signal > 0)
 250                                 break; // Other signal type
 251
 252                         size_t ia_pd_len, ia_na_len, ia_pd_new, ia_na_new;
 253                         odhcp6c_get_state(STATE_IA_PD, &ia_pd_len);
 254                         odhcp6c_get_state(STATE_IA_NA, &ia_na_len);
 255
 256                         // If we have any IAs, send renew, otherwise request
 257                         int r;
 258                         if (ia_pd_len == 0 && ia_na_len == 0)
 259                                 r = dhcpv6_request(DHCPV6_MSG_REQUEST);
 260                         else
 261                                 r = dhcpv6_request(DHCPV6_MSG_RENEW);
 262                         odhcp6c_signal_process();
 263                         if (r > 0) // Publish updates
 264                                 script_call("updated");
 265                         if (r >= 0)
 266                                 continue; // Renew was successful
 267
 268                         odhcp6c_clear_state(STATE_SERVER_ID); // Remove binding
 269
 270                         // If we have IAs, try rebind otherwise restart
 271                         res = dhcpv6_request(DHCPV6_MSG_REBIND);
 272                         odhcp6c_signal_process();
 273
 274                         odhcp6c_get_state(STATE_IA_PD, &ia_pd_new);
 275                         odhcp6c_get_state(STATE_IA_NA, &ia_na_new);
 276                         if (res < 0 || (ia_pd_new == 0 && ia_pd_len) ||
 277                                         (ia_na_new == 0 && ia_na_len))
 278                                 break; // We lost all our IAs, restart
 279                         else if (res > 0)
 280                                 script_call("rebound");
 281                 }
 282
 283
 284                 size_t ia_pd_len, ia_na_len, server_id_len;
 285                 odhcp6c_get_state(STATE_IA_PD, &ia_pd_len);
 286                 odhcp6c_get_state(STATE_IA_NA, &ia_na_len);
 287                 odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 288
 289                 // Add all prefixes to lost prefixes
 290                 bound = false;
 291                 script_call("unbound");
 292
 293                 if (server_id_len > 0 && (ia_pd_len > 0 || ia_na_len > 0) && release)
 294                         dhcpv6_request(DHCPV6_MSG_RELEASE);
 295
 296                 odhcp6c_clear_state(STATE_IA_NA);
 297                 odhcp6c_clear_state(STATE_IA_PD);
 298         }
 299
 300         script_call("stopped");
 301         return 0;
 302 }
 303
 304
 305 static int usage(void)
 306 {
 307         const char buf[] =
 308         "Usage: odhcp6c [options] <interface>\n"
 309         "\nFeature options:\n"
 310         "       -S              Don't allow SLAAC-only (implied by -P)\n"
 311         "       -N <mode>       Mode for requesting addresses [try|force|none]\n"
 312         "       -P <length>     Request IPv6-Prefix (0 = auto)\n"
 313         "       -c <clientid>   Override client-ID (base-16 encoded)\n"
 314         "       -r <options>    Options to be requested (comma-separated)\n"
 315         "       -s <script>     Status update script (/usr/sbin/odhcp6c-update)\n"
 316         "       -k              Don't send a RELEASE when stopping\n"
 317         "\nInvocation options:\n"
 318         "       -p <pidfile>    Set pidfile (/var/run/6relayd.pid)\n"
 319         "       -d              Daemonize\n"
 320         "       -e              Write logmessages to stderr\n"
 321         //"     -v              Increase logging verbosity\n"
 322         "       -h              Show this help\n\n";
 323         write(STDERR_FILENO, buf, sizeof(buf));
 324         return 1;
 325 }
 326
 327
 328 // Don't want to pull-in librt and libpthread just for a monotonic clock...
 329 uint64_t odhcp6c_get_milli_time(void)
 330 {
 331         struct timespec t = {0, 0};
 332         syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &t);
 333         return t.tv_sec * 1000 + t.tv_nsec / 1000000;
 334 }
 335
 336
 337 static uint8_t* odhcp6c_resize_state(enum odhcp6c_state state, ssize_t len)
 338 {
 339         if (len == 0)
 340                 return state_data[state] + state_len[state];
 341         else if (state_len[state] + len > 1024)
 342                 return NULL;
 343
 344         uint8_t *n = realloc(state_data[state], state_len[state] + len);
 345         if (n || state_len[state] + len == 0) {
 346                 state_data[state] = n;
 347                 n += state_len[state];
 348                 state_len[state] += len;
 349         }
 350         return n;
 351 }
 352
 353
 354 bool odhcp6c_signal_process(void)
 355 {
 356         if (do_signal == SIGIO) {
 357                 do_signal = 0;
 358                 bool updated = ra_process();
 359                 updated |= ra_rtnl_process();
 360                 if (updated && (bound || allow_slaac_only)) {
 361                         odhcp6c_expire();
 362                         script_call("ra-updated");
 363                 }
 364         }
 365
 366         return do_signal != 0;
 367 }
 368
 369
 370 void odhcp6c_clear_state(enum odhcp6c_state state)
 371 {
 372         state_len[state] = 0;
 373 }
 374
 375
 376 void odhcp6c_add_state(enum odhcp6c_state state, const void *data, size_t len)
 377 {
 378         uint8_t *n = odhcp6c_resize_state(state, len);
 379         if (n)
 380                 memcpy(n, data, len);
 381 }
 382
 383
 384 size_t odhcp6c_remove_state(enum odhcp6c_state state, size_t offset, size_t len)
 385 {
 386         uint8_t *data = state_data[state];
 387         ssize_t len_after = state_len[state] - (offset + len);
 388         if (len_after < 0)
 389                 return state_len[state];
 390
 391         memmove(data + offset, data + offset + len, len_after);
 392         return state_len[state] -= len;
 393 }
 394
 395
 396 void* odhcp6c_get_state(enum odhcp6c_state state, size_t *len)
 397 {
 398         *len = state_len[state];
 399         return state_data[state];
 400 }
 401
 402
 403 struct odhcp6c_entry* odhcp6c_find_entry(enum odhcp6c_state state, const struct odhcp6c_entry *new)
 404 {
 405         size_t len, cmplen = offsetof(struct odhcp6c_entry, target) + new->length / 8;
 406         struct odhcp6c_entry *start = odhcp6c_get_state(state, &len);
 407         struct odhcp6c_entry *x = NULL;
 408
 409         for (struct odhcp6c_entry *c = start; !x && c < &start[len/sizeof(*c)]; ++c)
 410                 if (!memcmp(c, new, cmplen))
 411                         return c;
 412
 413         return NULL;
 414 }
 415
 416
 417 void odhcp6c_update_entry_safe(enum odhcp6c_state state, struct odhcp6c_entry *new, uint32_t safe)
 418 {
 419         size_t len;
 420         struct odhcp6c_entry *x = odhcp6c_find_entry(state, new);
 421         struct odhcp6c_entry *start = odhcp6c_get_state(state, &len);
 422
 423         if (x && x->valid > new->valid && new->valid < safe)
 424                 new->valid = safe;
 425
 426         if (new->valid > 0) {
 427                 if (x) {
 428                         x->valid = new->valid;
 429                         x->preferred = new->preferred;
 430                 } else {
 431                         odhcp6c_add_state(state, new, sizeof(*new));
 432                 }
 433         } else if (x) {
 434                 odhcp6c_remove_state(state, (x - start) * sizeof(*x), sizeof(*x));
 435         }
 436 }
 437
 438
 439 void odhcp6c_update_entry(enum odhcp6c_state state, struct odhcp6c_entry *new)
 440 {
 441         odhcp6c_update_entry_safe(state, new, 0);
 442 }
 443
 444
 445 static void odhcp6c_expire_list(enum odhcp6c_state state, uint32_t elapsed)
 446 {
 447         size_t len;
 448         struct odhcp6c_entry *start = odhcp6c_get_state(state, &len);
 449         for (struct odhcp6c_entry *c = start; c < &start[len / sizeof(*c)]; ++c) {
 450                 if (c->preferred < elapsed)
 451                         c->preferred = 0;
 452                 else if (c->preferred != UINT32_MAX)
 453                         c->preferred -= elapsed;
 454
 455                 if (c->valid < elapsed)
 456                         c->valid = 0;
 457                 else if (c->valid != UINT32_MAX)
 458                         c->valid -= elapsed;
 459
 460                 if (!c->valid)
 461                         odhcp6c_remove_state(state, (c - start) * sizeof(*c), sizeof(*c));
 462         }
 463 }
 464
 465
 466 void odhcp6c_expire(void)
 467 {
 468         static time_t last_update = 0;
 469         time_t now = odhcp6c_get_milli_time() / 1000;
 470
 471         uint32_t elapsed = now - last_update;
 472         last_update = now;
 473
 474         odhcp6c_expire_list(STATE_RA_PREFIX, elapsed);
 475         odhcp6c_expire_list(STATE_RA_ROUTE, elapsed);
 476         odhcp6c_expire_list(STATE_RA_DNS, elapsed);
 477         odhcp6c_expire_list(STATE_IA_NA, elapsed);
 478         odhcp6c_expire_list(STATE_IA_PD, elapsed);
 479 }
 480
 481
 482 void odhcp6c_random(void *buf, size_t len)
 483 {
 484         read(urandom_fd, buf, len);
 485 }
 486
 487
 488 static void sighandler(int signal)
 489 {
 490         if (signal == SIGCHLD)
 491                 while (waitpid(-1, NULL, WNOHANG) > 0);
 492         else if (signal == SIGUSR1)
 493                 do_signal = SIGUSR1;
 494         else if (signal == SIGUSR2)
 495                 do_signal = SIGUSR2;
 496         else if (signal == SIGIO)
 497                 do_signal = SIGIO;
 498         else
 499                 do_signal = SIGTERM;
 500 }