src/dhcpv6.c

   1 /**
   2  * Copyright (C) 2012-2013 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 <fcntl.h>
  17 #include <errno.h>
  18 #include <stdlib.h>
  19 #include <signal.h>
  20 #include <limits.h>
  21 #include <resolv.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24 #include <syslog.h>
  25 #include <stdbool.h>
  26 #include <sys/time.h>
  27 #include <sys/ioctl.h>
  28 #include <sys/socket.h>
  29 #include <netinet/in.h>
  30
  31 #include <net/if.h>
  32 #include <net/ethernet.h>
  33
  34 #include "odhcp6c.h"
  35
  36
  37 #define ALL_DHCPV6_RELAYS {{{0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\
  38                 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x02}}}
  39 #define DHCPV6_CLIENT_PORT 546
  40 #define DHCPV6_SERVER_PORT 547
  41 #define DHCPV6_DUID_LLADDR 3
  42 #define DHCPV6_REQ_DELAY 1
  43
  44
  45 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
  46                 const uint8_t transaction[3], enum dhcpv6_msg type);
  47
  48 static uint32_t dhcpv6_parse_ia(void *opt, void *end);
  49
  50 static reply_handler dhcpv6_handle_reply;
  51 static reply_handler dhcpv6_handle_advert;
  52 static reply_handler dhcpv6_handle_rebind_reply;
  53 static reply_handler dhcpv6_handle_reconfigure;
  54 static int dhcpv6_commit_advert(void);
  55
  56
  57
  58 // RFC 3315 - 5.5 Timeout and Delay values
  59 static struct dhcpv6_retx dhcpv6_retx[_DHCPV6_MSG_MAX] = {
  60         [DHCPV6_MSG_UNKNOWN] = {false, 1, 120, "<POLL>",
  61                         dhcpv6_handle_reconfigure, NULL},
  62         [DHCPV6_MSG_SOLICIT] = {true, 1, 120, "SOLICIT",
  63                         dhcpv6_handle_advert, dhcpv6_commit_advert},
  64         [DHCPV6_MSG_REQUEST] = {true, 30, 10, "REQUEST",
  65                         dhcpv6_handle_reply, NULL},
  66         [DHCPV6_MSG_RENEW] = {false, 10, 600, "RENEW",
  67                         dhcpv6_handle_reply, NULL},
  68         [DHCPV6_MSG_REBIND] = {false, 10, 600, "REBIND",
  69                         dhcpv6_handle_rebind_reply, NULL},
  70         [DHCPV6_MSG_RELEASE] = {false, 1, 600, "RELEASE", NULL, NULL},
  71         [DHCPV6_MSG_DECLINE] = {false, 1, 3, "DECLINE", NULL, NULL},
  72         [DHCPV6_MSG_INFO_REQ] = {true, 1, 120, "INFOREQ",
  73                         dhcpv6_handle_reply, NULL},
  74 };
  75
  76
  77 // Sockets
  78 static int sock = -1;
  79 static int ifindex = -1;
  80 static int64_t t1 = 0, t2 = 0, t3 = 0;
  81
  82 // IA states
  83 static int request_prefix = -1;
  84 static enum odhcp6c_ia_mode na_mode = IA_MODE_NONE;
  85 static bool accept_reconfig = false;
  86
  87
  88
  89 int init_dhcpv6(const char *ifname, int request_pd)
  90 {
  91         request_prefix = request_pd;
  92
  93         sock = socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
  94
  95         // Detect interface
  96         struct ifreq ifr;
  97         strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
  98         if (ioctl(sock, SIOCGIFINDEX, &ifr))
  99                 return -1;
 100         ifindex = ifr.ifr_ifindex;
 101
 102         // Create client DUID
 103         size_t client_id_len;
 104         odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 105         if (client_id_len == 0) {
 106                 ioctl(sock, SIOCGIFHWADDR, &ifr);
 107                 uint8_t duid[14] = {0, DHCPV6_OPT_CLIENTID, 0, 10, 0,
 108                                 DHCPV6_DUID_LLADDR, 0, 1};
 109                 memcpy(&duid[8], ifr.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
 110
 111                 uint8_t zero[ETHER_ADDR_LEN] = {0, 0, 0, 0, 0, 0};
 112                 struct ifreq ifs[100], *ifp, *ifend;
 113                 struct ifconf ifc;
 114                 ifc.ifc_req = ifs;
 115                 ifc.ifc_len = sizeof(ifs);
 116
 117                 if (!memcmp(&duid[8], zero, ETHER_ADDR_LEN) &&
 118                                 ioctl(sock, SIOCGIFCONF, &ifc) >= 0) {
 119                         // If our interface doesn't have an address...
 120                         ifend = ifs + (ifc.ifc_len / sizeof(struct ifreq));
 121                         for (ifp = ifc.ifc_req; ifp < ifend &&
 122                                         !memcmp(&duid[8], zero, 6); ifp++) {
 123                                 memcpy(ifr.ifr_name, ifp->ifr_name,
 124                                                 sizeof(ifr.ifr_name));
 125                                 ioctl(sock, SIOCGIFHWADDR, &ifr);
 126                                 memcpy(&duid[8], ifr.ifr_hwaddr.sa_data,
 127                                                 ETHER_ADDR_LEN);
 128                         }
 129                 }
 130
 131                 odhcp6c_add_state(STATE_CLIENT_ID, duid, sizeof(duid));
 132         }
 133
 134         // Create ORO
 135         uint16_t oro[] = {htons(DHCPV6_OPT_DNS_SERVERS),
 136                         htons(DHCPV6_OPT_DNS_DOMAIN),
 137                         htons(DHCPV6_OPT_NTP_SERVER),
 138                         htons(DHCPV6_OPT_SIP_SERVER_A),
 139                         htons(DHCPV6_OPT_SIP_SERVER_D),
 140                         htons(DHCPV6_OPT_PD_EXCLUDE)};
 141         odhcp6c_add_state(STATE_ORO, oro, sizeof(oro));
 142
 143
 144         // Configure IPv6-options
 145         int val = 1;
 146         setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val));
 147         setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
 148         setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
 149
 150         struct sockaddr_in6 client_addr = { .sin6_family = AF_INET6,
 151                 .sin6_port = htons(DHCPV6_CLIENT_PORT), .sin6_flowinfo = 0 };
 152         if (bind(sock, (struct sockaddr*)&client_addr, sizeof(client_addr)))
 153                 return -1;
 154
 155         return 0;
 156 }
 157
 158
 159 void dhcpv6_set_ia_na_mode(enum odhcp6c_ia_mode mode)
 160 {
 161         na_mode = mode;
 162 }
 163
 164
 165 static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
 166 {
 167         // Build FQDN
 168         char fqdn_buf[256];
 169         gethostname(fqdn_buf, sizeof(fqdn_buf));
 170         struct {
 171                 uint16_t type;
 172                 uint16_t len;
 173                 uint8_t flags;
 174                 uint8_t data[256];
 175         } fqdn;
 176         size_t fqdn_len = 5 + dn_comp(fqdn_buf, fqdn.data,
 177                         sizeof(fqdn.data), NULL, NULL);
 178         fqdn.type = htons(DHCPV6_OPT_FQDN);
 179         fqdn.len = htons(fqdn_len - 4);
 180         fqdn.flags = 0;
 181
 182
 183         // Build Client ID
 184         size_t cl_id_len;
 185         void *cl_id = odhcp6c_get_state(STATE_CLIENT_ID, &cl_id_len);
 186
 187         // Get Server ID
 188         size_t srv_id_len;
 189         void *srv_id = odhcp6c_get_state(STATE_SERVER_ID, &srv_id_len);
 190
 191         // Build IA_PDs
 192         size_t ia_pd_entries, ia_pd_len = 0;
 193         struct odhcp6c_entry *e = odhcp6c_get_state(STATE_IA_PD, &ia_pd_entries);
 194         ia_pd_entries /= sizeof(*e);
 195         struct dhcpv6_ia_hdr hdr_ia_pd = {
 196                 htons(DHCPV6_OPT_IA_PD),
 197                 htons(sizeof(hdr_ia_pd) - 4),
 198                 1, 0, 0
 199         };
 200
 201
 202         uint8_t *ia_pd = alloca(ia_pd_entries * (sizeof(struct dhcpv6_ia_prefix) + 10));
 203         for (size_t i = 0; i < ia_pd_entries; ++i) {
 204                 uint8_t ex_len = 0;
 205                 if (e[i].priority > 0)
 206                         ex_len = ((e[i].priority - e[i].length - 1) / 8) + 6;
 207
 208                 struct dhcpv6_ia_prefix p = {
 209                         .type = htons(DHCPV6_OPT_IA_PREFIX),
 210                         .len = htons(sizeof(p) - 4U + ex_len),
 211                         .prefix = e[i].length,
 212                         .addr = e[i].target
 213                 };
 214
 215                 memcpy(ia_pd + ia_pd_len, &p, sizeof(p));
 216                 ia_pd_len += sizeof(p);
 217
 218                 if (ex_len) {
 219                         ia_pd[ia_pd_len++] = 0;
 220                         ia_pd[ia_pd_len++] = DHCPV6_OPT_PD_EXCLUDE;
 221                         ia_pd[ia_pd_len++] = 0;
 222                         ia_pd[ia_pd_len++] = ex_len - 4;
 223                         ia_pd[ia_pd_len++] = e[i].priority;
 224
 225                         uint32_t excl = ntohl(e[i].router.s6_addr32[1]);
 226                         excl >>= (64 - e[i].priority);
 227                         excl <<= 8 - ((e[i].priority - e[i].length) % 8);
 228
 229                         for (size_t i = ex_len - 5; i > 0; --i, excl >>= 8)
 230                                 ia_pd[ia_pd_len + i] = excl & 0xff;
 231                         ia_pd_len += ex_len - 5;
 232                 }
 233         }
 234
 235         struct dhcpv6_ia_prefix pref = {
 236                 .type = htons(DHCPV6_OPT_IA_PREFIX),
 237                 .len = htons(25), .prefix = request_prefix
 238         };
 239         if (request_prefix > 0 && ia_pd_len == 0 &&
 240                         (type == DHCPV6_MSG_SOLICIT ||
 241                         type == DHCPV6_MSG_REQUEST)) {
 242                 ia_pd = (uint8_t*)&pref;
 243                 ia_pd_len = sizeof(pref);
 244         }
 245         hdr_ia_pd.len = htons(ntohs(hdr_ia_pd.len) + ia_pd_len);
 246
 247         // Build IA_NAs
 248         size_t ia_na_entries, ia_na_len = 0;
 249         void *ia_na = NULL;
 250         e = odhcp6c_get_state(STATE_IA_NA, &ia_na_entries);
 251         ia_na_entries /= sizeof(*e);
 252
 253         struct dhcpv6_ia_hdr hdr_ia_na = {
 254                 htons(DHCPV6_OPT_IA_NA),
 255                 htons(sizeof(hdr_ia_na) - 4),
 256                 1, 0, 0
 257         };
 258
 259         struct dhcpv6_ia_addr pa[ia_na_entries];
 260         for (size_t i = 0; i < ia_na_entries; ++i) {
 261                 pa[i].type = htons(DHCPV6_OPT_IA_ADDR);
 262                 pa[i].len = htons(sizeof(pa[i]) - 4U);
 263                 pa[i].addr = e[i].target;
 264                 pa[i].preferred = 0;
 265                 pa[i].valid = 0;
 266         }
 267
 268         ia_na = pa;
 269         ia_na_len = sizeof(pa);
 270         hdr_ia_na.len = htons(ntohs(hdr_ia_na.len) + ia_na_len);
 271
 272         // Reconfigure Accept
 273         struct {
 274                 uint16_t type;
 275                 uint16_t length;
 276         } reconf_accept = {htons(DHCPV6_OPT_RECONF_ACCEPT), 0};
 277
 278         // Request Information Refresh
 279         uint16_t oro_refresh = htons(DHCPV6_OPT_INFO_REFRESH);
 280
 281         // Prepare Header
 282         size_t oro_len;
 283         void *oro = odhcp6c_get_state(STATE_ORO, &oro_len);
 284         struct {
 285                 uint8_t type;
 286                 uint8_t trid[3];
 287                 uint16_t elapsed_type;
 288                 uint16_t elapsed_len;
 289                 uint16_t elapsed_value;
 290                 uint16_t oro_type;
 291                 uint16_t oro_len;
 292         } hdr = {
 293                 type, {trid[0], trid[1], trid[2]},
 294                 htons(DHCPV6_OPT_ELAPSED), htons(2),
 295                         htons((ecs > 0xffff) ? 0xffff : ecs),
 296                 htons(DHCPV6_OPT_ORO), htons(oro_len),
 297         };
 298
 299         struct iovec iov[] = {
 300                 {&hdr, sizeof(hdr)},
 301                 {oro, oro_len},
 302                 {&oro_refresh, 0},
 303                 {cl_id, cl_id_len},
 304                 {srv_id, srv_id_len},
 305                 {&reconf_accept, 0},
 306                 {&fqdn, fqdn_len},
 307                 {&hdr_ia_na, sizeof(hdr_ia_na)},
 308                 {ia_na, ia_na_len},
 309                 {&hdr_ia_pd, sizeof(hdr_ia_pd)},
 310                 {ia_pd, ia_pd_len},
 311         };
 312
 313         size_t cnt = ARRAY_SIZE(iov);
 314         if (type == DHCPV6_MSG_INFO_REQ) {
 315                 cnt = 5;
 316                 iov[2].iov_len = sizeof(oro_refresh);
 317                 hdr.oro_len = htons(oro_len + sizeof(oro_refresh));
 318         } else if (!request_prefix) {
 319                 cnt = 9;
 320         }
 321
 322         // Disable IAs if not used
 323         if (type == DHCPV6_MSG_SOLICIT) {
 324                 iov[5].iov_len = sizeof(reconf_accept);
 325         } else if (type != DHCPV6_MSG_REQUEST) {
 326                 if (ia_na_len == 0)
 327                         iov[7].iov_len = 0;
 328                 if (ia_pd_len == 0)
 329                         iov[9].iov_len = 0;
 330         }
 331
 332         if (na_mode == IA_MODE_NONE)
 333                 iov[7].iov_len = 0;
 334
 335         struct sockaddr_in6 srv = {AF_INET6, htons(DHCPV6_SERVER_PORT),
 336                 0, ALL_DHCPV6_RELAYS, ifindex};
 337         struct msghdr msg = {&srv, sizeof(srv), iov, cnt, NULL, 0, 0};
 338
 339         sendmsg(sock, &msg, 0);
 340 }
 341
 342
 343 static int64_t dhcpv6_rand_delay(int64_t time)
 344 {
 345         int random;
 346         odhcp6c_random(&random, sizeof(random));
 347         return (time * (random % 1000)) / 10000;
 348 }
 349
 350
 351 int dhcpv6_request(enum dhcpv6_msg type)
 352 {
 353         uint8_t buf[1536];
 354         uint32_t timeout = UINT32_MAX;
 355         struct dhcpv6_retx *retx = &dhcpv6_retx[type];
 356
 357         if (retx->delay) {
 358                 struct timespec ts = {0, 0};
 359                 ts.tv_nsec = dhcpv6_rand_delay(10 * DHCPV6_REQ_DELAY);
 360                 nanosleep(&ts, NULL);
 361         }
 362
 363         if (type == DHCPV6_MSG_RELEASE || type == DHCPV6_MSG_DECLINE)
 364                 timeout = 3;
 365         else if (type == DHCPV6_MSG_UNKNOWN)
 366                 timeout = t1;
 367         else if (type == DHCPV6_MSG_RENEW)
 368                 timeout = t2 - t1;
 369         else if (type == DHCPV6_MSG_REBIND)
 370                 timeout = t3 - t2;
 371
 372         if (timeout == 0)
 373                 return -1;
 374
 375         syslog(LOG_NOTICE, "Sending %s (timeout %us)", retx->name, timeout);
 376
 377         uint64_t start = odhcp6c_get_milli_time(), round_start = start, elapsed;
 378
 379         // Generate transaction ID
 380         uint8_t trid[3];
 381         odhcp6c_random(trid, sizeof(trid));
 382         ssize_t len = -1;
 383         int64_t rto = 0;
 384
 385         do {
 386                 rto = (rto == 0) ? (retx->init_timeo * 1000 +
 387                                 dhcpv6_rand_delay(retx->init_timeo * 1000)) :
 388                                 (2 * rto + dhcpv6_rand_delay(rto));
 389
 390                 if (rto >= retx->max_timeo * 1000)
 391                         rto = retx->max_timeo * 1000 +
 392                                 dhcpv6_rand_delay(retx->max_timeo * 1000);
 393
 394                 // Calculate end for this round and elapsed time
 395                 uint64_t round_end = round_start + rto;
 396                 elapsed = round_start - start;
 397
 398                 // Don't wait too long
 399                 if (round_end - start > timeout * 1000)
 400                         round_end = timeout * 1000 + start;
 401
 402                 // Built and send package
 403                 if (type != DHCPV6_MSG_UNKNOWN)
 404                         dhcpv6_send(type, trid, elapsed / 10);
 405
 406                 // Receive rounds
 407                 for (; len < 0 && round_start < round_end;
 408                                 round_start = odhcp6c_get_milli_time()) {
 409                         // Check for pending signal
 410                         if (odhcp6c_signal_process())
 411                                 return -1;
 412
 413                         // Set timeout for receiving
 414                         uint64_t t = round_end - round_start;
 415                         struct timeval timeout = {t / 1000, (t % 1000) * 1000};
 416                         setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
 417                                         &timeout, sizeof(timeout));
 418
 419                         // Receive cycle
 420                         len = recv(sock, buf, sizeof(buf), 0);
 421
 422                         if (!dhcpv6_response_is_valid(buf, len, trid, type))
 423                                 len = -1;
 424
 425                         if (len > 0) {
 426                                 uint8_t *opt = &buf[4];
 427                                 uint8_t *opt_end = opt + len - 4;
 428
 429                                 round_start = odhcp6c_get_milli_time();
 430                                 elapsed = round_start - start;
 431                                 syslog(LOG_NOTICE, "Got a valid reply after "
 432                                                 "%ums", (unsigned)elapsed);
 433
 434                                 if (retx->handler_reply)
 435                                         len = retx->handler_reply(
 436                                                         type, opt, opt_end);
 437
 438                                 if (round_end - round_start > 1000)
 439                                         round_end = 1000 + round_start;
 440                         }
 441                 }
 442
 443                 // Allow
 444                 if (retx->handler_finish)
 445                         len = retx->handler_finish();
 446         } while (len < 0 && elapsed / 1000 < timeout);
 447
 448         return len;
 449 }
 450
 451
 452 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
 453                 const uint8_t transaction[3], enum dhcpv6_msg type)
 454 {
 455         const struct dhcpv6_header *rep = buf;
 456         if (len < (ssize_t)sizeof(*rep) || memcmp(rep->tr_id,
 457                         transaction, sizeof(rep->tr_id)))
 458                 return false; // Invalid reply
 459
 460         if (type == DHCPV6_MSG_SOLICIT) {
 461                 if (rep->msg_type != DHCPV6_MSG_ADVERT &&
 462                                 rep->msg_type != DHCPV6_MSG_REPLY)
 463                         return false;
 464         } else if (type == DHCPV6_MSG_UNKNOWN) {
 465                 if (!accept_reconfig || rep->msg_type != DHCPV6_MSG_RECONF)
 466                         return false;
 467         } else if (rep->msg_type != DHCPV6_MSG_REPLY) {
 468                 return false;
 469         }
 470
 471         uint8_t *end = ((uint8_t*)buf) + len, *odata;
 472         uint16_t otype, olen;
 473         bool clientid_ok = false, serverid_ok = false;
 474
 475         size_t client_id_len, server_id_len;
 476         void *client_id = odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 477         void *server_id = odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 478
 479         dhcpv6_for_each_option(&rep[1], end, otype, olen, odata)
 480                 if (otype == DHCPV6_OPT_CLIENTID)
 481                         clientid_ok = (olen + 4U == client_id_len) && !memcmp(
 482                                         &odata[-4], client_id, client_id_len);
 483                 else if (otype == DHCPV6_OPT_SERVERID)
 484                         serverid_ok = (olen + 4U == server_id_len) && !memcmp(
 485                                         &odata[-4], server_id, server_id_len);
 486
 487         return clientid_ok && (serverid_ok || server_id_len == 0);
 488 }
 489
 490
 491 int dhcpv6_poll_reconfigure(void)
 492 {
 493         int ret = dhcpv6_request(DHCPV6_MSG_UNKNOWN);
 494         if (ret != -1)
 495                 ret = dhcpv6_request(ret);
 496
 497         return ret;
 498 }
 499
 500
 501 static int dhcpv6_handle_reconfigure(_unused enum dhcpv6_msg orig,
 502                 const void *opt, const void *end)
 503 {
 504         // TODO: should verify the reconfigure message
 505         uint16_t otype, olen;
 506         uint8_t *odata, msg = DHCPV6_MSG_RENEW;
 507         dhcpv6_for_each_option(opt, end, otype, olen, odata)
 508                 if (otype == DHCPV6_OPT_RECONF_MESSAGE && olen == 1 && (
 509                                 odata[0] == DHCPV6_MSG_RENEW ||
 510                                 odata[0] == DHCPV6_MSG_INFO_REQ))
 511                         msg = odata[0];
 512
 513         dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 514         return msg;
 515 }
 516
 517
 518 // Collect all advertised servers
 519 static int dhcpv6_handle_advert(_unused enum dhcpv6_msg orig,
 520                 const void *opt, const void *end)
 521 {
 522         uint16_t olen, otype;
 523         uint8_t *odata;
 524         struct dhcpv6_server_cand cand = {false, false, 0, 0, {0}};
 525
 526         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 527                 if (otype == DHCPV6_OPT_SERVERID && olen <= 130) {
 528                         memcpy(cand.duid, odata, olen);
 529                         cand.duid_len = olen;
 530                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 531                                 && odata[1] == DHCPV6_NoAddrsAvail) {
 532                         if (na_mode == IA_MODE_FORCE) {
 533                                 return -1;
 534                         } else {
 535                                 cand.has_noaddravail = true;
 536                                 cand.preference -= 1000;
 537                         }
 538                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 539                                 && odata[1] == DHCPV6_NoPrefixAvail) {
 540                         cand.preference -= 2000;
 541                 } else if (otype == DHCPV6_OPT_PREF && olen >= 1 &&
 542                                 cand.preference >= 0) {
 543                         cand.preference = odata[0];
 544                 } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
 545                         cand.wants_reconfigure = true;
 546                 } else if (otype == DHCPV6_OPT_IA_PD && request_prefix) {
 547                         struct dhcpv6_ia_hdr *h = (void*)odata;
 548                         uint8_t *oend = odata + olen, *d;
 549                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d) {
 550                                 if (otype == DHCPV6_OPT_IA_PREFIX)
 551                                         cand.preference += 2000;
 552                                 else if (otype == DHCPV6_OPT_STATUS &&
 553                                                 olen >= 2 && d[0] == 0 &&
 554                                                 d[1] == DHCPV6_NoPrefixAvail)
 555                                         cand.preference -= 2000;
 556                         }
 557                 }
 558         }
 559
 560         if (cand.duid_len > 0)
 561                 odhcp6c_add_state(STATE_SERVER_CAND, &cand, sizeof(cand));
 562
 563         return -1;
 564 }
 565
 566
 567 static int dhcpv6_commit_advert(void)
 568 {
 569         size_t cand_len;
 570         struct dhcpv6_server_cand *c = NULL, *cand =
 571                         odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
 572
 573         bool retry = false;
 574         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 575                 if (cand[i].has_noaddravail)
 576                         retry = true; // We want to try again
 577
 578                 if (!c || c->preference < cand[i].preference)
 579                         c = &cand[i];
 580         }
 581
 582         if (retry && na_mode == IA_MODE_TRY) {
 583                 // We give it a second try without the IA_NA
 584                 na_mode = IA_MODE_NONE;
 585                 return dhcpv6_request(DHCPV6_MSG_SOLICIT);
 586         }
 587
 588         if (c) {
 589                 uint16_t hdr[2] = {htons(DHCPV6_OPT_SERVERID),
 590                                 htons(c->duid_len)};
 591                 odhcp6c_add_state(STATE_SERVER_ID, hdr, sizeof(hdr));
 592                 odhcp6c_add_state(STATE_SERVER_ID, c->duid, c->duid_len);
 593                 accept_reconfig = c->wants_reconfigure;
 594         }
 595
 596         odhcp6c_clear_state(STATE_SERVER_CAND);
 597
 598         if (!c)
 599                 return -1;
 600         else if (request_prefix || na_mode != IA_MODE_NONE)
 601                 return DHCPV6_STATEFUL;
 602         else
 603                 return DHCPV6_STATELESS;
 604 }
 605
 606
 607 static int dhcpv6_handle_rebind_reply(enum dhcpv6_msg orig,
 608                 const void *opt, const void *end)
 609 {
 610         dhcpv6_handle_advert(orig, opt, end);
 611         if (dhcpv6_commit_advert() < 0) {
 612                 dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 613                 return -1;
 614         }
 615
 616         return dhcpv6_handle_reply(orig, opt, end);
 617 }
 618
 619
 620 static int dhcpv6_handle_reply(enum dhcpv6_msg orig,
 621                 const void *opt, const void *end)
 622 {
 623         uint8_t *odata;
 624         uint16_t otype, olen;
 625
 626         static time_t last_update = 0;
 627         time_t now = odhcp6c_get_milli_time() / 1000;
 628
 629         uint32_t elapsed = now - last_update;
 630         odhcp6c_expire();
 631
 632         if (orig == DHCPV6_MSG_UNKNOWN) {
 633                 t1 -= elapsed;
 634                 t2 -= elapsed;
 635                 t3 -= elapsed;
 636
 637                 if (t1 < 0)
 638                         t1 = 0;
 639
 640                 if (t2 < 0)
 641                         t2 = 0;
 642
 643                 if (t3 < 0)
 644                         t3 = 0;
 645         } else {
 646                 t1 = t2 = t3 = UINT32_MAX;
 647         }
 648
 649         if (opt) {
 650                 odhcp6c_clear_state(STATE_DNS);
 651                 odhcp6c_clear_state(STATE_SEARCH);
 652                 odhcp6c_clear_state(STATE_SNTP_IP);
 653                 odhcp6c_clear_state(STATE_SNTP_FQDN);
 654                 odhcp6c_clear_state(STATE_SIP_IP);
 655                 odhcp6c_clear_state(STATE_SIP_FQDN);
 656         }
 657
 658         // Parse and find all matching IAs
 659         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 660                 if ((otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA)
 661                                 && olen > sizeof(struct dhcpv6_ia_hdr)) {
 662                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 663                         uint32_t l_t1 = ntohl(ia_hdr->t1);
 664                         uint32_t l_t2 = ntohl(ia_hdr->t2);
 665
 666                         // Test ID and T1-T2 validity
 667                         if (ia_hdr->iaid != 1 || l_t2 < l_t1)
 668                                 continue;
 669
 670                         bool error = false;
 671                         uint16_t stype, slen;
 672                         uint8_t *sdata;
 673                         // Test status and bail if error
 674                         dhcpv6_for_each_option(&ia_hdr[1], odata + olen,
 675                                         stype, slen, sdata)
 676                                 if (stype == DHCPV6_OPT_STATUS && slen >= 2 &&
 677                                                 (sdata[0] || sdata[1]))
 678                                         error = true;
 679
 680                         if (error)
 681                                 continue;
 682
 683                         // Update times
 684                         if (l_t1 > 0 && t1 > l_t1)
 685                                 t1 = l_t1;
 686
 687                         if (l_t2 > 0 && t2 > l_t2)
 688                                 t2 = l_t2;
 689
 690                         uint32_t n = dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 691
 692                         if (n < t1)
 693                                 t1 = n;
 694
 695                         if (n < t2)
 696                                 t2 = n;
 697
 698                         if (n < t3)
 699                                 t3 = n;
 700
 701                         if (t2 >= t3)
 702                                 t2 = 8 * t3 / 10;
 703
 704                         if (t1 >= t2)
 705                                 t1 = 5 * t2 / 8;
 706
 707                 } else if (otype == DHCPV6_OPT_DNS_SERVERS) {
 708                         if (olen % 16 == 0)
 709                                 odhcp6c_add_state(STATE_DNS, odata, olen);
 710                 } else if (otype == DHCPV6_OPT_DNS_DOMAIN) {
 711                         odhcp6c_add_state(STATE_SEARCH, odata, olen);
 712                 } else if (otype == DHCPV6_OPT_NTP_SERVER) {
 713                         uint16_t stype, slen;
 714                         uint8_t *sdata;
 715                         // Test status and bail if error
 716                         dhcpv6_for_each_option(odata, odata + olen,
 717                                         stype, slen, sdata) {
 718                                 if (slen == 16 && (stype == NTP_MC_ADDR ||
 719                                                 stype == NTP_SRV_ADDR))
 720                                         odhcp6c_add_state(STATE_SNTP_IP,
 721                                                         sdata, slen);
 722                                 else if (slen > 0 && stype == NTP_SRV_FQDN)
 723                                         odhcp6c_add_state(STATE_SNTP_FQDN,
 724                                                         sdata, slen);
 725                         }
 726                 } else if (otype == DHCPV6_OPT_SIP_SERVER_A) {
 727                         if (olen == 16)
 728                                 odhcp6c_add_state(STATE_SIP_IP, odata, olen);
 729                 } else if (otype == DHCPV6_OPT_SIP_SERVER_D) {
 730                         odhcp6c_add_state(STATE_SIP_FQDN, odata, olen);
 731                 } else if (otype == DHCPV6_OPT_INFO_REFRESH && olen >= 4) {
 732                         uint32_t refresh = ntohl(*((uint32_t*)odata));
 733                         if (refresh < (uint32_t)t1)
 734                                 t1 = refresh;
 735                 } else if (otype != DHCPV6_OPT_CLIENTID &&
 736                                 otype != DHCPV6_OPT_SERVERID) {
 737                         odhcp6c_add_state(STATE_CUSTOM_OPTS,
 738                                         &odata[-4], olen + 4);
 739                 }
 740         }
 741
 742         return true;
 743 }
 744
 745
 746 static uint32_t dhcpv6_parse_ia(void *opt, void *end)
 747 {
 748         uint32_t timeout = UINT32_MAX; // Minimum timeout
 749         uint16_t otype, olen;
 750         uint8_t *odata;
 751
 752         struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT,
 753                         0, 0, IN6ADDR_ANY_INIT, 0, 0};
 754
 755         // Update address IA
 756         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 757                 if (otype == DHCPV6_OPT_IA_PREFIX) {
 758                         struct dhcpv6_ia_prefix *prefix = (void*)&odata[-4];
 759                         if (olen + 4U < sizeof(*prefix))
 760                                 continue;
 761
 762                         entry.valid = ntohl(prefix->valid);
 763                         entry.preferred = ntohl(prefix->preferred);
 764
 765                         if (entry.preferred > entry.valid)
 766                                 continue;
 767
 768                         entry.length = prefix->prefix;
 769                         entry.target = prefix->addr;
 770
 771                         // Parse PD-exclude
 772                         bool ok = true;
 773                         uint16_t stype, slen;
 774                         uint8_t *sdata;
 775                         dhcpv6_for_each_option(odata + sizeof(*prefix) - 4U,
 776                                         odata + olen, stype, slen, sdata) {
 777                                 if (stype != DHCPV6_OPT_PD_EXCLUDE || slen < 2)
 778                                         continue;
 779
 780                                 uint8_t elen = sdata[0];
 781                                 if (elen > 64)
 782                                         elen = 64;
 783
 784                                 if (elen <= 32 || elen <= entry.length) {
 785                                         ok = false;
 786                                         continue;
 787                                 }
 788
 789
 790                                 uint8_t bytes = ((elen - entry.length - 1) / 8) + 1;
 791                                 if (slen <= bytes) {
 792                                         ok = false;
 793                                         continue;
 794                                 }
 795
 796                                 uint32_t exclude = 0;
 797                                 do {
 798                                         exclude = exclude << 8 | sdata[bytes];
 799                                 } while (--bytes);
 800
 801                                 exclude >>= 8 - ((elen - entry.length) % 8);
 802                                 exclude <<= 64 - elen;
 803
 804                                 // Abusing router & priority fields for exclusion
 805                                 entry.router = entry.target;
 806                                 entry.router.s6_addr32[1] |= htonl(exclude);
 807                                 entry.priority = elen;
 808                         }
 809
 810                         if (ok)
 811                                 odhcp6c_update_entry(STATE_IA_PD, &entry);
 812
 813                         entry.priority = 0;
 814                         memset(&entry.router, 0, sizeof(entry.router));
 815                 } else if (otype == DHCPV6_OPT_IA_ADDR) {
 816                         struct dhcpv6_ia_addr *addr = (void*)&odata[-4];
 817                         if (olen + 4U < sizeof(*addr))
 818                                 continue;
 819
 820                         entry.preferred = ntohl(addr->preferred);
 821                         entry.valid = ntohl(addr->valid);
 822
 823                         if (entry.preferred > entry.valid)
 824                                 continue;
 825
 826                         entry.length = 128;
 827                         entry.target = addr->addr;
 828
 829                         odhcp6c_update_entry(STATE_IA_NA, &entry);
 830                 }
 831
 832                 if (entry.valid > 0 && timeout > entry.valid)
 833                         timeout = entry.valid;
 834         }
 835
 836         return timeout;
 837 }