networking/udhcp/dhcpc.c

   1 /* vi: set sw=4 ts=4: */
   2 /* dhcpc.c
   3  *
   4  * udhcp DHCP client
   5  *
   6  * Russ Dill <Russ.Dill@asu.edu> July 2001
   7  *
   8  * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
   9  */
  10
  11 #include <getopt.h>
  12
  13 #include "common.h"
  14 #include "dhcpd.h"
  15 #include "dhcpc.h"
  16 #include "options.h"
  17
  18
  19 static int state;
  20 /* Something is definitely wrong here. IPv4 addresses
  21  * in variables of type long?? BTW, we use inet_ntoa()
  22  * in the code. Manpage says that struct in_addr has a member of type long (!)
  23  * which holds IPv4 address, and the struct is passed by value (!!)
  24  */
  25 static unsigned long requested_ip; /* = 0 */
  26 static unsigned long server_addr;
  27 static unsigned long timeout;
  28 static int packet_num; /* = 0 */
  29 static int fd = -1;
  30
  31 #define LISTEN_NONE 0
  32 #define LISTEN_KERNEL 1
  33 #define LISTEN_RAW 2
  34 static int listen_mode;
  35
  36 struct client_config_t client_config;
  37
  38
  39 /* just a little helper */
  40 static void change_mode(int new_mode)
  41 {
  42         DEBUG("entering %s listen mode",
  43                 new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
  44         if (fd >= 0) close(fd);
  45         fd = -1;
  46         listen_mode = new_mode;
  47 }
  48
  49
  50 /* perform a renew */
  51 static void perform_renew(void)
  52 {
  53         bb_info_msg("Performing a DHCP renew");
  54         switch (state) {
  55         case BOUND:
  56                 change_mode(LISTEN_KERNEL);
  57         case RENEWING:
  58         case REBINDING:
  59                 state = RENEW_REQUESTED;
  60                 break;
  61         case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
  62                 udhcp_run_script(NULL, "deconfig");
  63         case REQUESTING:
  64         case RELEASED:
  65                 change_mode(LISTEN_RAW);
  66                 state = INIT_SELECTING;
  67                 break;
  68         case INIT_SELECTING:
  69                 break;
  70         }
  71
  72         /* start things over */
  73         packet_num = 0;
  74
  75         /* Kill any timeouts because the user wants this to hurry along */
  76         timeout = 0;
  77 }
  78
  79
  80 /* perform a release */
  81 static void perform_release(void)
  82 {
  83         char buffer[16];
  84         struct in_addr temp_addr;
  85
  86         /* send release packet */
  87         if (state == BOUND || state == RENEWING || state == REBINDING) {
  88                 temp_addr.s_addr = server_addr;
  89                 sprintf(buffer, "%s", inet_ntoa(temp_addr));
  90                 temp_addr.s_addr = requested_ip;
  91                 bb_info_msg("Unicasting a release of %s to %s",
  92                                 inet_ntoa(temp_addr), buffer);
  93                 send_release(server_addr, requested_ip); /* unicast */
  94                 udhcp_run_script(NULL, "deconfig");
  95         }
  96         bb_info_msg("Entering released state");
  97
  98         change_mode(LISTEN_NONE);
  99         state = RELEASED;
 100         timeout = 0x7fffffff;
 101 }
 102
 103
 104 static void client_background(void)
 105 {
 106         udhcp_background(client_config.pidfile);
 107         client_config.foreground = 1; /* Do not fork again. */
 108         client_config.background_if_no_lease = 0;
 109 }
 110
 111
 112 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
 113 {
 114         uint8_t *storage;
 115         int len = strlen(str);
 116         if (len > 255) len = 255;
 117         storage = xzalloc(len + extra + OPT_DATA);
 118         storage[OPT_CODE] = code;
 119         storage[OPT_LEN] = len + extra;
 120         memcpy(storage + extra + OPT_DATA, str, len);
 121         return storage;
 122 }
 123
 124
 125 int udhcpc_main(int argc, char *argv[])
 126 {
 127         uint8_t *temp, *message;
 128         char *str_c, *str_V, *str_h, *str_F, *str_r, *str_T, *str_t;
 129         unsigned long t1 = 0, t2 = 0, xid = 0;
 130         unsigned long start = 0, lease = 0;
 131         long now;
 132         unsigned opt;
 133         int max_fd;
 134         int sig;
 135         int retval;
 136         int len;
 137         int no_clientid = 0;
 138         fd_set rfds;
 139         struct timeval tv;
 140         struct dhcpMessage packet;
 141         struct in_addr temp_addr;
 142
 143         enum {
 144                 OPT_c = 1 << 0,
 145                 OPT_C = 1 << 1,
 146                 OPT_V = 1 << 2,
 147                 OPT_f = 1 << 3,
 148                 OPT_b = 1 << 4,
 149                 OPT_H = 1 << 5,
 150                 OPT_h = 1 << 6,
 151                 OPT_F = 1 << 7,
 152                 OPT_i = 1 << 8,
 153                 OPT_n = 1 << 9,
 154                 OPT_p = 1 << 10,
 155                 OPT_q = 1 << 11,
 156                 OPT_R = 1 << 12,
 157                 OPT_r = 1 << 13,
 158                 OPT_s = 1 << 14,
 159                 OPT_T = 1 << 15,
 160                 OPT_t = 1 << 16,
 161                 OPT_v = 1 << 17,
 162         };
 163         static const struct option arg_options[] = {
 164                 { "clientid",   required_argument,      0, 'c' },
 165                 { "clientid-none", no_argument,         0, 'C' },
 166                 { "vendorclass", required_argument,     0, 'V' },
 167                 { "foreground", no_argument,            0, 'f' },
 168                 { "background", no_argument,            0, 'b' },
 169                 { "hostname",   required_argument,      0, 'H' },
 170                 { "hostname",   required_argument,      0, 'h' },
 171                 { "fqdn",       required_argument,      0, 'F' },
 172                 { "interface",  required_argument,      0, 'i' },
 173                 { "now",        no_argument,            0, 'n' },
 174                 { "pidfile",    required_argument,      0, 'p' },
 175                 { "quit",       no_argument,            0, 'q' },
 176                 { "release",    no_argument,            0, 'R' },
 177                 { "request",    required_argument,      0, 'r' },
 178                 { "script",     required_argument,      0, 's' },
 179                 { "timeout",    required_argument,      0, 'T' },
 180                 { "version",    no_argument,            0, 'v' },
 181                 { "retries",    required_argument,      0, 't' },
 182                 { 0, 0, 0, 0 }
 183         };
 184
 185         /* Default options. */
 186         client_config.interface = "eth0";
 187         client_config.script = DEFAULT_SCRIPT;
 188         client_config.retries = 3;
 189         client_config.timeout = 3;
 190
 191         /* Parse command line */
 192         opt_complementary = "?:c--C:C--c" // mutually exclusive
 193                             ":hH:Hh"; // -h and -H are the same
 194         applet_long_options = arg_options;
 195         opt = getopt32(argc, argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:v",
 196                 &str_c, &str_V, &str_h, &str_h, &str_F,
 197                 &client_config.interface, &client_config.pidfile, &str_r,
 198                 &client_config.script, &str_T, &str_t
 199                 );
 200
 201         if (opt & OPT_c)
 202                 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0);
 203         if (opt & OPT_C)
 204                 no_clientid = 1;
 205         if (opt & OPT_V)
 206                 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
 207         if (opt & OPT_f)
 208                 client_config.foreground = 1;
 209         if (opt & OPT_b)
 210                 client_config.background_if_no_lease = 1;
 211         if (opt & OPT_h)
 212                 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
 213         if (opt & OPT_F) {
 214                 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
 215                 /* Flags: 0000NEOS
 216                 S: 1 => Client requests Server to update A RR in DNS as well as PTR
 217                 O: 1 => Server indicates to client that DNS has been updated regardless
 218                 E: 1 => Name data is DNS format, i.e. <4>host<6>domain<4>com<0> not "host.domain.com"
 219                 N: 1 => Client requests Server to not update DNS
 220                 */
 221                 client_config.fqdn[OPT_DATA + 0] = 0x1;
 222                 /* client_config.fqdn[OPT_DATA + 1] = 0; - redundant */
 223                 /* client_config.fqdn[OPT_DATA + 2] = 0; - redundant */
 224         }
 225         // if (opt & OPT_i) client_config.interface = ...
 226         if (opt & OPT_n)
 227                 client_config.abort_if_no_lease = 1;
 228         // if (opt & OPT_p) client_config.pidfile = ...
 229         if (opt & OPT_q)
 230                 client_config.quit_after_lease = 1;
 231         if (opt & OPT_R)
 232                 client_config.release_on_quit = 1;
 233         if (opt & OPT_r)
 234                 requested_ip = inet_addr(str_r);
 235         // if (opt & OPT_s) client_config.script = ...
 236         if (opt & OPT_T)
 237                 client_config.timeout = xatoi_u(str_T);
 238         if (opt & OPT_t)
 239                 client_config.retries = xatoi_u(str_t);
 240         if (opt & OPT_v) {
 241                 printf("version %s\n\n", BB_VER);
 242                 return 0;
 243         }
 244
 245         /* Start the log, sanitize fd's, and write a pid file */
 246         udhcp_start_log_and_pid(client_config.pidfile);
 247
 248         if (read_interface(client_config.interface, &client_config.ifindex,
 249                            NULL, client_config.arp) < 0)
 250                 return 1;
 251
 252         /* if not set, and not suppressed, setup the default client ID */
 253         if (!client_config.clientid && !no_clientid) {
 254                 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
 255                 client_config.clientid[OPT_DATA] = 1;
 256                 memcpy(client_config.clientid + OPT_DATA+1, client_config.arp, 6);
 257         }
 258
 259         if (!client_config.vendorclass)
 260                 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, "udhcp "BB_VER, 0);
 261
 262         /* setup the signal pipe */
 263         udhcp_sp_setup();
 264
 265         state = INIT_SELECTING;
 266         udhcp_run_script(NULL, "deconfig");
 267         change_mode(LISTEN_RAW);
 268
 269         for (;;) {
 270                 tv.tv_sec = timeout - uptime();
 271                 tv.tv_usec = 0;
 272
 273                 if (listen_mode != LISTEN_NONE && fd < 0) {
 274                         if (listen_mode == LISTEN_KERNEL)
 275                                 fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
 276                         else
 277                                 fd = raw_socket(client_config.ifindex);
 278                         if (fd < 0) {
 279                                 bb_perror_msg("FATAL: cannot listen on socket");
 280                                 return 0;
 281                         }
 282                 }
 283                 max_fd = udhcp_sp_fd_set(&rfds, fd);
 284
 285                 if (tv.tv_sec > 0) {
 286                         DEBUG("Waiting on select...");
 287                         retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
 288                 } else retval = 0; /* If we already timed out, fall through */
 289
 290                 now = uptime();
 291                 if (retval == 0) {
 292                         /* timeout dropped to zero */
 293                         switch (state) {
 294                         case INIT_SELECTING:
 295                                 if (packet_num < client_config.retries) {
 296                                         if (packet_num == 0)
 297                                                 xid = random_xid();
 298
 299                                         /* send discover packet */
 300                                         send_discover(xid, requested_ip); /* broadcast */
 301
 302                                         timeout = now + client_config.timeout;
 303                                         packet_num++;
 304                                 } else {
 305                                         udhcp_run_script(NULL, "leasefail");
 306                                         if (client_config.background_if_no_lease) {
 307                                                 bb_info_msg("No lease, forking to background");
 308                                                 client_background();
 309                                         } else if (client_config.abort_if_no_lease) {
 310                                                 bb_info_msg("No lease, failing");
 311                                                 return 1;
 312                                         }
 313                                         /* wait to try again */
 314                                         packet_num = 0;
 315                                         timeout = now + 60;
 316                                 }
 317                                 break;
 318                         case RENEW_REQUESTED:
 319                         case REQUESTING:
 320                                 if (packet_num < client_config.retries) {
 321                                         /* send request packet */
 322                                         if (state == RENEW_REQUESTED)
 323                                                 send_renew(xid, server_addr, requested_ip); /* unicast */
 324                                         else send_selecting(xid, server_addr, requested_ip); /* broadcast */
 325
 326                                         timeout = now + ((packet_num == 2) ? 10 : 2);
 327                                         packet_num++;
 328                                 } else {
 329                                         /* timed out, go back to init state */
 330                                         if (state == RENEW_REQUESTED) udhcp_run_script(NULL, "deconfig");
 331                                         state = INIT_SELECTING;
 332                                         timeout = now;
 333                                         packet_num = 0;
 334                                         change_mode(LISTEN_RAW);
 335                                 }
 336                                 break;
 337                         case BOUND:
 338                                 /* Lease is starting to run out, time to enter renewing state */
 339                                 state = RENEWING;
 340                                 change_mode(LISTEN_KERNEL);
 341                                 DEBUG("Entering renew state");
 342                                 /* fall right through */
 343                         case RENEWING:
 344                                 /* Either set a new T1, or enter REBINDING state */
 345                                 if ((t2 - t1) <= (lease / 14400 + 1)) {
 346                                         /* timed out, enter rebinding state */
 347                                         state = REBINDING;
 348                                         timeout = now + (t2 - t1);
 349                                         DEBUG("Entering rebinding state");
 350                                 } else {
 351                                         /* send a request packet */
 352                                         send_renew(xid, server_addr, requested_ip); /* unicast */
 353
 354                                         t1 = (t2 - t1) / 2 + t1;
 355                                         timeout = t1 + start;
 356                                 }
 357                                 break;
 358                         case REBINDING:
 359                                 /* Either set a new T2, or enter INIT state */
 360                                 if ((lease - t2) <= (lease / 14400 + 1)) {
 361                                         /* timed out, enter init state */
 362                                         state = INIT_SELECTING;
 363                                         bb_info_msg("Lease lost, entering init state");
 364                                         udhcp_run_script(NULL, "deconfig");
 365                                         timeout = now;
 366                                         packet_num = 0;
 367                                         change_mode(LISTEN_RAW);
 368                                 } else {
 369                                         /* send a request packet */
 370                                         send_renew(xid, 0, requested_ip); /* broadcast */
 371
 372                                         t2 = (lease - t2) / 2 + t2;
 373                                         timeout = t2 + start;
 374                                 }
 375                                 break;
 376                         case RELEASED:
 377                                 /* yah, I know, *you* say it would never happen */
 378                                 timeout = 0x7fffffff;
 379                                 break;
 380                         }
 381                 } else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
 382                         /* a packet is ready, read it */
 383
 384                         if (listen_mode == LISTEN_KERNEL)
 385                                 len = udhcp_get_packet(&packet, fd);
 386                         else len = get_raw_packet(&packet, fd);
 387
 388                         if (len == -1 && errno != EINTR) {
 389                                 DEBUG("error on read, %s, reopening socket", strerror(errno));
 390                                 change_mode(listen_mode); /* just close and reopen */
 391                         }
 392                         if (len < 0) continue;
 393
 394                         if (packet.xid != xid) {
 395                                 DEBUG("Ignoring XID %lx (our xid is %lx)",
 396                                         (unsigned long) packet.xid, xid);
 397                                 continue;
 398                         }
 399
 400                         /* Ignore packets that aren't for us */
 401                         if (memcmp(packet.chaddr, client_config.arp, 6)) {
 402                                 DEBUG("Packet does not have our chaddr - ignoring");
 403                                 continue;
 404                         }
 405
 406                         if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 407                                 bb_error_msg("cannot get option from packet - ignoring");
 408                                 continue;
 409                         }
 410
 411                         switch (state) {
 412                         case INIT_SELECTING:
 413                                 /* Must be a DHCPOFFER to one of our xid's */
 414                                 if (*message == DHCPOFFER) {
 415                                         temp = get_option(&packet, DHCP_SERVER_ID);
 416                                         if (temp) {
 417                                                 server_addr = *(uint32_t*)temp;
 418                                                 xid = packet.xid;
 419                                                 requested_ip = packet.yiaddr;
 420
 421                                                 /* enter requesting state */
 422                                                 state = REQUESTING;
 423                                                 timeout = now;
 424                                                 packet_num = 0;
 425                                         } else {
 426                                                 bb_error_msg("no server ID in message");
 427                                         }
 428                                 }
 429                                 break;
 430                         case RENEW_REQUESTED:
 431                         case REQUESTING:
 432                         case RENEWING:
 433                         case REBINDING:
 434                                 if (*message == DHCPACK) {
 435                                         temp = get_option(&packet, DHCP_LEASE_TIME);
 436                                         if (!temp) {
 437                                                 bb_error_msg("no lease time with ACK, using 1 hour lease");
 438                                                 lease = 60 * 60;
 439                                         } else {
 440                                                 lease = ntohl(*(uint32_t*)temp);
 441                                         }
 442
 443                                         /* enter bound state */
 444                                         t1 = lease / 2;
 445
 446                                         /* little fixed point for n * .875 */
 447                                         t2 = (lease * 0x7) >> 3;
 448                                         temp_addr.s_addr = packet.yiaddr;
 449                                         bb_info_msg("Lease of %s obtained, lease time %ld",
 450                                                 inet_ntoa(temp_addr), lease);
 451                                         start = now;
 452                                         timeout = t1 + start;
 453                                         requested_ip = packet.yiaddr;
 454                                         udhcp_run_script(&packet,
 455                                                    ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
 456
 457                                         state = BOUND;
 458                                         change_mode(LISTEN_NONE);
 459                                         if (client_config.quit_after_lease) {
 460                                                 if (client_config.release_on_quit)
 461                                                         perform_release();
 462                                                 return 0;
 463                                         }
 464                                         if (!client_config.foreground)
 465                                                 client_background();
 466
 467                                 } else if (*message == DHCPNAK) {
 468                                         /* return to init state */
 469                                         bb_info_msg("Received DHCP NAK");
 470                                         udhcp_run_script(&packet, "nak");
 471                                         if (state != REQUESTING)
 472                                                 udhcp_run_script(NULL, "deconfig");
 473                                         state = INIT_SELECTING;
 474                                         timeout = now;
 475                                         requested_ip = 0;
 476                                         packet_num = 0;
 477                                         change_mode(LISTEN_RAW);
 478                                         sleep(3); /* avoid excessive network traffic */
 479                                 }
 480                                 break;
 481                         /* case BOUND, RELEASED: - ignore all packets */
 482                         }
 483                 } else if (retval > 0 && (sig = udhcp_sp_read(&rfds))) {
 484                         switch (sig) {
 485                         case SIGUSR1:
 486                                 perform_renew();
 487                                 break;
 488                         case SIGUSR2:
 489                                 perform_release();
 490                                 break;
 491                         case SIGTERM:
 492                                 bb_info_msg("Received SIGTERM");
 493                                 if (client_config.release_on_quit)
 494                                         perform_release();
 495                                 return 0;
 496                         }
 497                 } else if (retval == -1 && errno == EINTR) {
 498                         /* a signal was caught */
 499                 } else {
 500                         /* An error occured */
 501                         bb_perror_msg("select");
 502                 }
 503
 504         }
 505         return 0;
 506 }