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 <unistd.h>
  21 #include <syslog.h>
  22 #include <signal.h>
  23 #include <string.h>
  24 #include <stdbool.h>
  25
  26 #include <net/if.h>
  27 #include <sys/wait.h>
  28 #include <sys/syscall.h>
  29
  30 #include "odhcp6c.h"
  31
  32
  33 static void sighandler(int signal);
  34 static int sysctl_interface(const char *ifname, const char *option,
  35                 const char *data);
  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
  44
  45 int main(_unused int argc, char* const argv[])
  46 {
  47         openlog("odhcp6c", LOG_PERROR | LOG_PID, LOG_DAEMON);
  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, reset = false;
  59         int c, request_pd = 0, timeout = 0;
  60         while ((c = getopt(argc, argv, "RN:P:c:r:s:t:hdp:")) != -1) {
  61                 switch (c) {
  62                 case 'R':
  63                         reset = true;
  64                         break;
  65
  66                 case 'N':
  67                         if (!strcmp(optarg, "force"))
  68                                 ia_na_mode = IA_MODE_FORCE;
  69                         else if (!strcmp(optarg, "none"))
  70                                 ia_na_mode = IA_MODE_NONE;
  71                         else if (!strcmp(optarg, "try"))
  72                                 ia_na_mode = IA_MODE_TRY;
  73                         else
  74                                 help = true;
  75                         break;
  76
  77                 case 'P':
  78                         request_pd = strtoul(optarg, NULL, 10);
  79                         if (request_pd == 0)
  80                                 request_pd = -1;
  81                         break;
  82
  83                 case 'c':
  84                         l = script_unhexlify(&buf[4], sizeof(buf) - 4, optarg);
  85                         if (l > 0) {
  86                                 buf[0] = 0;
  87                                 buf[1] = DHCPV6_OPT_CLIENTID;
  88                                 buf[2] = 0;
  89                                 buf[4] = l;
  90                                 odhcp6c_add_state(STATE_CLIENT_ID, buf, l + 4);
  91                         } else {
  92                                 help = true;
  93                         }
  94                         break;
  95
  96                 case 'r':
  97                         optpos = optarg;
  98                         while (optpos[0]) {
  99                                 opttype = htons(strtoul(optarg, &optpos, 10));
 100                                 if (optpos == optarg)
 101                                         break;
 102                                 else if (optpos[0])
 103                                         optarg = &optpos[1];
 104                                 odhcp6c_add_state(STATE_ORO, &opttype, 2);
 105                         }
 106                         break;
 107
 108                 case 's':
 109                         script = optarg;
 110                         break;
 111
 112                 case 't':
 113                         timeout = strtoul(optarg, NULL, 10);
 114                         break;
 115
 116                 case 'd':
 117                         daemonize = true;
 118                         break;
 119
 120                 case 'p':
 121                         pidfile = optarg;
 122                         break;
 123
 124                 default:
 125                         help = true;
 126                         break;
 127                 }
 128         }
 129
 130         const char *ifname = argv[optind];
 131
 132         if (help || !ifname)
 133                 return usage();
 134
 135         if (init_dhcpv6(ifname, request_pd) || init_rtnetlink() ||
 136                         script_init(script, ifname)) {
 137                 syslog(LOG_ERR, "failed to initialize: %s", strerror(errno));
 138                 return 3;
 139         }
 140
 141         signal(SIGHUP, sighandler);
 142         signal(SIGINT, sighandler);
 143         signal(SIGALRM, sighandler);
 144         signal(SIGCHLD, sighandler);
 145         signal(SIGTERM, sighandler);
 146         signal(SIGUSR1, sighandler);
 147         signal(SIGUSR2, sighandler);
 148
 149         // Configure interface to accept RA
 150         if (reset) {
 151                 sysctl_interface(ifname, "accept_ra", "2");
 152                 sysctl_interface(ifname, "disable_ipv6", "1");
 153                 sysctl_interface(ifname, "disable_ipv6", "0");
 154         }
 155
 156         if (daemonize) {
 157                 openlog("odhcp6c", LOG_PID, LOG_DAEMON); // Disable LOG_PERROR
 158                 if (daemon(0, 0)) {
 159                         syslog(LOG_ERR, "Failed to daemonize: %s",
 160                                         strerror(errno));
 161                         return 4;
 162                 }
 163
 164                 char pidbuf[128];
 165                 if (!pidfile) {
 166                         snprintf(pidbuf, sizeof(pidbuf),
 167                                         "/var/run/odhcp6c.%s.pid", ifname);
 168                         pidfile = pidbuf;
 169                 }
 170
 171                 int fd = open(pidfile, O_WRONLY | O_CREAT);
 172                 if (fd >= 0) {
 173                         char buf[8];
 174                         int len = snprintf(buf, sizeof(buf), "%i\n", getpid());
 175                         write(fd, buf, len);
 176                         close(fd);
 177                 }
 178         }
 179
 180         while (do_signal != SIGTERM) { // Main logic
 181                 odhcp6c_clear_state(STATE_SERVER_ID);
 182                 odhcp6c_clear_state(STATE_SERVER_CAND);
 183                 odhcp6c_clear_state(STATE_IA_PD);
 184                 odhcp6c_clear_state(STATE_IA_PD_LOST);
 185                 dhcpv6_set_ia_na_mode(ia_na_mode);
 186
 187                 alarm(timeout);
 188                 do_signal = 0;
 189                 int res = dhcpv6_request(DHCPV6_MSG_SOLICIT);
 190
 191                 if (res < 0) {
 192                         continue; // Might happen if we got a signal
 193                 } else if (res == DHCPV6_STATELESS) { // Stateless mode
 194                         while (do_signal == 0 || do_signal == SIGUSR1) {
 195                                 do_signal = 0;
 196
 197                                 res = dhcpv6_request(DHCPV6_MSG_INFO_REQ);
 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                                 alarm(0);
 206                                 if (dhcpv6_poll_reconfigure() > 0)
 207                                         script_call("informed");
 208                         }
 209
 210                         if (do_signal == SIGALRM)
 211                                 script_call("timeout");
 212
 213                         continue;
 214                 }
 215
 216                 // Stateful mode
 217                 if (dhcpv6_request(DHCPV6_MSG_REQUEST) < 0)
 218                         continue;
 219
 220                 script_call("bound");
 221                 alarm(0);
 222
 223                 while (do_signal == 0 || do_signal == SIGUSR1) {
 224                         // Renew Cycle
 225                         // Wait for T1 to expire or until we get a reconfigure
 226                         int res = dhcpv6_poll_reconfigure();
 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                         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
 260                         odhcp6c_get_state(STATE_IA_PD, &ia_pd_new);
 261                         odhcp6c_get_state(STATE_IA_NA, &ia_na_new);
 262                         if (res < 0 || (ia_pd_new == 0 && ia_pd_len) ||
 263                                         (ia_na_new == 0 && ia_na_len))
 264                                 break; // We lost all our IAs, restart
 265                         else if (res > 0)
 266                                 script_call("rebound");
 267                 }
 268
 269
 270                 size_t ia_pd_len, ia_na_len, server_id_len;
 271                 uint8_t *ia_pd = odhcp6c_get_state(STATE_IA_PD, &ia_pd_len);
 272                 odhcp6c_get_state(STATE_IA_NA, &ia_na_len);
 273                 odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 274
 275                 // Add all prefixes to lost prefixes
 276                 odhcp6c_add_state(STATE_IA_PD_LOST, ia_pd, ia_pd_len);
 277                 odhcp6c_clear_state(STATE_IA_PD);
 278
 279                 if (do_signal == SIGALRM)
 280                         script_call("timeout");
 281                 else
 282                         script_call("unbound");
 283
 284                 // Remove assigned addresses
 285                 if (ia_na_len > 0)
 286                         dhcpv6_remove_addrs();
 287
 288                 if (server_id_len > 0 && (ia_pd_len > 0 || ia_na_len > 0))
 289                         dhcpv6_request(DHCPV6_MSG_RELEASE);
 290         }
 291
 292         return 0;
 293 }
 294
 295
 296 static int usage(void)
 297 {
 298         const char buf[] =
 299         "Usage: odhcp6c [options] <interface>\n"
 300         "\nFeature options:\n"
 301         "       -N <mode>       Mode for requesting addresses [try|force|none]\n"
 302         "       -P <length>     Request IPv6-Prefix (0 = auto)\n"
 303         "       -c <clientid>   Override client-ID (base-16 encoded)\n"
 304         "       -r <options>    Options to be requested (comma-separated)\n"
 305         "       -s <script>     Status update script (/usr/sbin/odhcp6c-update)\n"
 306         "       -t <timeout>    Request timeout after which the script is called\n"
 307         "\nInvocation options:\n"
 308         "       -p <pidfile>    Set pidfile (/var/run/6relayd.pid)\n"
 309         "       -d              Daemonize\n"
 310         //"     -v              Increase logging verbosity\n"
 311         "       -h              Show this help\n\n";
 312         write(STDERR_FILENO, buf, sizeof(buf));
 313         return 1;
 314 }
 315
 316
 317 // Don't want to pull-in librt and libpthread just for a monotonic clock...
 318 uint64_t adhc6c_get_milli_time(void)
 319 {
 320         struct timespec t = {0, 0};
 321         syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &t);
 322         return t.tv_sec * 1000 + t.tv_nsec / 1000000;
 323 }
 324
 325
 326 static uint8_t* odhcp6c_resize_state(enum odhcp6c_state state, ssize_t len)
 327 {
 328         if (len == 0)
 329                 return state_data[state] + state_len[state];
 330
 331         uint8_t *n = realloc(state_data[state], state_len[state] + len);
 332         if (n || state_len[state] + len == 0) {
 333                 state_data[state] = n;
 334                 n += state_len[state];
 335                 state_len[state] += len;
 336         }
 337         return n;
 338 }
 339
 340
 341 bool odhcp6c_signal_is_pending(void)
 342 {
 343         return do_signal != 0;
 344 }
 345
 346
 347 void odhcp6c_clear_state(enum odhcp6c_state state)
 348 {
 349         state_len[state] = 0;
 350 }
 351
 352
 353 void odhcp6c_add_state(enum odhcp6c_state state, const void *data, size_t len)
 354 {
 355         uint8_t *n = odhcp6c_resize_state(state, len);
 356         if (n)
 357                 memcpy(n, data, len);
 358 }
 359
 360
 361 size_t odhcp6c_remove_state(enum odhcp6c_state state, size_t offset, size_t len)
 362 {
 363         uint8_t *data = state_data[state];
 364         ssize_t len_after = state_len[state] - (offset + len);
 365         if (len_after < 0)
 366                 return state_len[state];
 367
 368         memmove(data + offset, data + offset + len, len_after);
 369         return state_len[state] -= len;
 370 }
 371
 372
 373 bool odhcp6c_commit_state(enum odhcp6c_state state, size_t old_len)
 374 {
 375         size_t new_len = state_len[state] - old_len;
 376         uint8_t *old_data = state_data[state], *new_data = old_data + old_len;
 377         bool upd = new_len != old_len || memcmp(old_data, new_data, new_len);
 378
 379         memmove(old_data, new_data, new_len);
 380         odhcp6c_resize_state(state, -old_len);
 381
 382         return upd;
 383 }
 384
 385
 386 void* odhcp6c_get_state(enum odhcp6c_state state, size_t *len)
 387 {
 388         *len = state_len[state];
 389         return state_data[state];
 390 }
 391
 392
 393 static int sysctl_interface(const char *ifname, const char *option,
 394                 const char *data)
 395 {
 396         char pathbuf[64];
 397         const char *sysctl_pattern = "/proc/sys/net/ipv6/conf/%s/%s";
 398         snprintf(pathbuf, sizeof(pathbuf), sysctl_pattern, ifname, option);
 399
 400         int fd = open(pathbuf, O_WRONLY);
 401         int written = write(fd, data, strlen(data));
 402         close(fd);
 403
 404         return (written > 0) ? 0 : -1;
 405 }
 406
 407
 408 static void sighandler(int signal)
 409 {
 410         if (signal == SIGCHLD)
 411                 while (waitpid(-1, NULL, WNOHANG) > 0);
 412         else if (signal == SIGUSR1)
 413                 do_signal = SIGUSR1;
 414         else if (signal == SIGUSR2)
 415                 do_signal = SIGUSR2;
 416         else if (signal == SIGALRM)
 417                 do_signal = SIGALRM;
 418         else
 419                 do_signal = SIGTERM;
 420 }