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