src/dhcpv6.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 <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_PREFIX_CLASS)
 139                          };
 140         odhcp6c_add_state(STATE_ORO, oro, sizeof(oro));
 141
 142
 143         // Configure IPv6-options
 144         int val = 1;
 145         setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val));
 146         setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
 147         setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
 148
 149         struct sockaddr_in6 client_addr = { .sin6_family = AF_INET6,
 150                 .sin6_port = htons(DHCPV6_CLIENT_PORT), .sin6_flowinfo = 0 };
 151         if (bind(sock, (struct sockaddr*)&client_addr, sizeof(client_addr)))
 152                 return -1;
 153
 154         return 0;
 155 }
 156
 157
 158 void dhcpv6_set_ia_na_mode(enum odhcp6c_ia_mode mode)
 159 {
 160         na_mode = mode;
 161 }
 162
 163
 164 static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
 165 {
 166         // Build FQDN
 167         char fqdn_buf[256];
 168         gethostname(fqdn_buf, sizeof(fqdn_buf));
 169         struct {
 170                 uint16_t type;
 171                 uint16_t len;
 172                 uint8_t flags;
 173                 uint8_t data[256];
 174         } fqdn;
 175         size_t fqdn_len = 5 + dn_comp(fqdn_buf, fqdn.data,
 176                         sizeof(fqdn.data), NULL, NULL);
 177         fqdn.type = htons(DHCPV6_OPT_FQDN);
 178         fqdn.len = htons(fqdn_len - 4);
 179         fqdn.flags = 0;
 180
 181
 182         // Build Client ID
 183         size_t cl_id_len;
 184         void *cl_id = odhcp6c_get_state(STATE_CLIENT_ID, &cl_id_len);
 185
 186         // Get Server ID
 187         size_t srv_id_len;
 188         void *srv_id = odhcp6c_get_state(STATE_SERVER_ID, &srv_id_len);
 189
 190         // Build IA_PDs
 191         size_t ia_pd_entries, ia_pd_len = 0;
 192         void *ia_pd = NULL;
 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         struct dhcpv6_ia_prefix pref = {
 202                 .type = htons(DHCPV6_OPT_IA_PREFIX),
 203                 .len = htons(25), .prefix = request_prefix
 204         };
 205
 206
 207         struct dhcpv6_ia_prefix p[ia_pd_entries];
 208         for (size_t i = 0; i < ia_pd_entries; ++i) {
 209                 p[i].type = htons(DHCPV6_OPT_IA_PREFIX);
 210                 p[i].len = htons(sizeof(p[i]) - 4U);
 211                 p[i].preferred = 0;
 212                 p[i].valid = 0;
 213                 p[i].prefix = e[i].length;
 214                 p[i].addr = e[i].target;
 215         }
 216         ia_pd = p;
 217         ia_pd_len = sizeof(p);
 218         hdr_ia_pd.len = htons(ntohs(hdr_ia_pd.len) + ia_pd_len);
 219
 220         if (request_prefix > 0 &&
 221                         (type == DHCPV6_MSG_SOLICIT ||
 222                         type == DHCPV6_MSG_REQUEST)) {
 223                 ia_pd = &pref;
 224                 ia_pd_len = sizeof(pref);
 225                 hdr_ia_pd.len = htons(ntohs(hdr_ia_pd.len) + ia_pd_len);
 226         }
 227
 228         // Build IA_NAs
 229         size_t ia_na_entries, ia_na_len = 0;
 230         void *ia_na = NULL;
 231         e = odhcp6c_get_state(STATE_IA_NA, &ia_na_entries);
 232         ia_na_entries /= sizeof(*e);
 233
 234         struct dhcpv6_ia_hdr hdr_ia_na = {
 235                 htons(DHCPV6_OPT_IA_NA),
 236                 htons(sizeof(hdr_ia_na) - 4),
 237                 1, 0, 0
 238         };
 239
 240         struct dhcpv6_ia_addr pa[ia_na_entries];
 241         for (size_t i = 0; i < ia_na_entries; ++i) {
 242                 pa[i].type = htons(DHCPV6_OPT_IA_ADDR);
 243                 pa[i].len = htons(sizeof(pa[i]) - 4U);
 244                 pa[i].addr = e[i].target;
 245                 pa[i].preferred = 0;
 246                 pa[i].valid = 0;
 247         }
 248
 249         ia_na = pa;
 250         ia_na_len = sizeof(pa);
 251         hdr_ia_na.len = htons(ntohs(hdr_ia_na.len) + ia_na_len);
 252
 253         // Reconfigure Accept
 254         struct {
 255                 uint16_t type;
 256                 uint16_t length;
 257         } reconf_accept = {htons(DHCPV6_OPT_RECONF_ACCEPT), 0};
 258
 259         // Request Information Refresh
 260         uint16_t oro_refresh = htons(DHCPV6_OPT_INFO_REFRESH);
 261
 262         // Prepare Header
 263         size_t oro_len;
 264         void *oro = odhcp6c_get_state(STATE_ORO, &oro_len);
 265         struct {
 266                 uint8_t type;
 267                 uint8_t trid[3];
 268                 uint16_t elapsed_type;
 269                 uint16_t elapsed_len;
 270                 uint16_t elapsed_value;
 271                 uint16_t oro_type;
 272                 uint16_t oro_len;
 273         } hdr = {
 274                 type, {trid[0], trid[1], trid[2]},
 275                 htons(DHCPV6_OPT_ELAPSED), htons(2),
 276                         htons((ecs > 0xffff) ? 0xffff : ecs),
 277                 htons(DHCPV6_OPT_ORO), htons(oro_len),
 278         };
 279
 280         struct iovec iov[] = {
 281                 {&hdr, sizeof(hdr)},
 282                 {oro, oro_len},
 283                 {&oro_refresh, 0},
 284                 {cl_id, cl_id_len},
 285                 {srv_id, srv_id_len},
 286                 {&reconf_accept, 0},
 287                 {&fqdn, fqdn_len},
 288                 {&hdr_ia_na, sizeof(hdr_ia_na)},
 289                 {ia_na, ia_na_len},
 290                 {&hdr_ia_pd, sizeof(hdr_ia_pd)},
 291                 {ia_pd, ia_pd_len},
 292         };
 293
 294         size_t cnt = ARRAY_SIZE(iov);
 295         if (type == DHCPV6_MSG_INFO_REQ) {
 296                 cnt = 5;
 297                 iov[2].iov_len = sizeof(oro_refresh);
 298                 hdr.oro_len = htons(oro_len + sizeof(oro_refresh));
 299         } else if (!request_prefix) {
 300                 cnt = 9;
 301         }
 302
 303         // Disable IAs if not used
 304         if (type == DHCPV6_MSG_SOLICIT) {
 305                 iov[5].iov_len = sizeof(reconf_accept);
 306         } else if (type != DHCPV6_MSG_REQUEST) {
 307                 if (ia_na_len == 0)
 308                         iov[7].iov_len = 0;
 309                 if (ia_pd_len == 0)
 310                         iov[9].iov_len = 0;
 311         }
 312
 313         if (na_mode == IA_MODE_NONE)
 314                 iov[7].iov_len = 0;
 315
 316         struct sockaddr_in6 srv = {AF_INET6, htons(DHCPV6_SERVER_PORT),
 317                 0, ALL_DHCPV6_RELAYS, ifindex};
 318         struct msghdr msg = {&srv, sizeof(srv), iov, cnt, NULL, 0, 0};
 319
 320         sendmsg(sock, &msg, 0);
 321 }
 322
 323
 324 static int64_t dhcpv6_rand_delay(int64_t time)
 325 {
 326         int random;
 327         odhcp6c_random(&random, sizeof(random));
 328         return (time * (random % 1000)) / 10000;
 329 }
 330
 331
 332 int dhcpv6_request(enum dhcpv6_msg type)
 333 {
 334         uint8_t buf[1536];
 335         uint32_t timeout = UINT32_MAX;
 336         struct dhcpv6_retx *retx = &dhcpv6_retx[type];
 337
 338         if (retx->delay) {
 339                 struct timespec ts = {0, 0};
 340                 ts.tv_nsec = dhcpv6_rand_delay(10 * DHCPV6_REQ_DELAY);
 341                 nanosleep(&ts, NULL);
 342         }
 343
 344         if (type == DHCPV6_MSG_RELEASE || type == DHCPV6_MSG_DECLINE)
 345                 timeout = 3;
 346         else if (type == DHCPV6_MSG_UNKNOWN)
 347                 timeout = t1;
 348         else if (type == DHCPV6_MSG_RENEW)
 349                 timeout = t2 - t1;
 350         else if (type == DHCPV6_MSG_REBIND)
 351                 timeout = t3 - t2;
 352
 353         if (timeout == 0)
 354                 return -1;
 355
 356         syslog(LOG_NOTICE, "Sending %s (timeout %us)", retx->name, timeout);
 357
 358         uint64_t start = odhcp6c_get_milli_time(), round_start = start, elapsed;
 359
 360         // Generate transaction ID
 361         uint8_t trid[3];
 362         odhcp6c_random(trid, sizeof(trid));
 363         ssize_t len = -1;
 364         int64_t rto = 0;
 365
 366         do {
 367                 rto = (rto == 0) ? (retx->init_timeo * 1000 +
 368                                 dhcpv6_rand_delay(retx->init_timeo * 1000)) :
 369                                 (2 * rto + dhcpv6_rand_delay(rto));
 370
 371                 if (rto >= retx->max_timeo * 1000)
 372                         rto = retx->max_timeo * 1000 +
 373                                 dhcpv6_rand_delay(retx->max_timeo * 1000);
 374
 375                 // Calculate end for this round and elapsed time
 376                 uint64_t round_end = round_start + rto;
 377                 elapsed = round_start - start;
 378
 379                 // Don't wait too long
 380                 if (round_end - start > timeout * 1000)
 381                         round_end = timeout * 1000 + start;
 382
 383                 // Built and send package
 384                 if (type != DHCPV6_MSG_UNKNOWN)
 385                         dhcpv6_send(type, trid, elapsed / 10);
 386
 387                 // Receive rounds
 388                 for (; len < 0 && round_start < round_end;
 389                                 round_start = odhcp6c_get_milli_time()) {
 390                         // Check for pending signal
 391                         if (odhcp6c_signal_process())
 392                                 return -1;
 393
 394                         // Set timeout for receiving
 395                         uint64_t t = round_end - round_start;
 396                         struct timeval timeout = {t / 1000, (t % 1000) * 1000};
 397                         setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
 398                                         &timeout, sizeof(timeout));
 399
 400                         // Receive cycle
 401                         len = recv(sock, buf, sizeof(buf), 0);
 402
 403                         if (!dhcpv6_response_is_valid(buf, len, trid, type))
 404                                 len = -1;
 405
 406                         if (len > 0) {
 407                                 uint8_t *opt = &buf[4];
 408                                 uint8_t *opt_end = opt + len - 4;
 409
 410                                 round_start = odhcp6c_get_milli_time();
 411                                 elapsed = round_start - start;
 412                                 syslog(LOG_NOTICE, "Got a valid reply after "
 413                                                 "%ums", (unsigned)elapsed);
 414
 415                                 if (retx->handler_reply)
 416                                         len = retx->handler_reply(
 417                                                         type, opt, opt_end);
 418
 419                                 if (round_end - round_start > 1000)
 420                                         round_end = 1000 + round_start;
 421                         }
 422                 }
 423
 424                 // Allow
 425                 if (retx->handler_finish)
 426                         len = retx->handler_finish();
 427         } while (len < 0 && elapsed / 1000 < timeout);
 428
 429         return len;
 430 }
 431
 432
 433 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
 434                 const uint8_t transaction[3], enum dhcpv6_msg type)
 435 {
 436         const struct dhcpv6_header *rep = buf;
 437         if (len < (ssize_t)sizeof(*rep) || memcmp(rep->tr_id,
 438                         transaction, sizeof(rep->tr_id)))
 439                 return false; // Invalid reply
 440
 441         if (type == DHCPV6_MSG_SOLICIT) {
 442                 if (rep->msg_type != DHCPV6_MSG_ADVERT &&
 443                                 rep->msg_type != DHCPV6_MSG_REPLY)
 444                         return false;
 445         } else if (type == DHCPV6_MSG_UNKNOWN) {
 446                 if (!accept_reconfig || rep->msg_type != DHCPV6_MSG_RECONF)
 447                         return false;
 448         } else if (rep->msg_type != DHCPV6_MSG_REPLY) {
 449                 return false;
 450         }
 451
 452         uint8_t *end = ((uint8_t*)buf) + len, *odata;
 453         uint16_t otype, olen;
 454         bool clientid_ok = false, serverid_ok = false;
 455
 456         size_t client_id_len, server_id_len;
 457         void *client_id = odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 458         void *server_id = odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 459
 460         dhcpv6_for_each_option(&rep[1], end, otype, olen, odata)
 461                 if (otype == DHCPV6_OPT_CLIENTID)
 462                         clientid_ok = (olen + 4U == client_id_len) && !memcmp(
 463                                         &odata[-4], client_id, client_id_len);
 464                 else if (otype == DHCPV6_OPT_SERVERID)
 465                         serverid_ok = (olen + 4U == server_id_len) && !memcmp(
 466                                         &odata[-4], server_id, server_id_len);
 467
 468         return clientid_ok && (serverid_ok || server_id_len == 0);
 469 }
 470
 471
 472 int dhcpv6_poll_reconfigure(void)
 473 {
 474         int ret = dhcpv6_request(DHCPV6_MSG_UNKNOWN);
 475         if (ret != -1)
 476                 ret = dhcpv6_request(ret);
 477
 478         return ret;
 479 }
 480
 481
 482 static int dhcpv6_handle_reconfigure(_unused enum dhcpv6_msg orig,
 483                 const void *opt, const void *end)
 484 {
 485         // TODO: should verify the reconfigure message
 486         uint16_t otype, olen;
 487         uint8_t *odata, msg = DHCPV6_MSG_RENEW;
 488         dhcpv6_for_each_option(opt, end, otype, olen, odata)
 489                 if (otype == DHCPV6_OPT_RECONF_MESSAGE && olen == 1 && (
 490                                 odata[0] == DHCPV6_MSG_RENEW ||
 491                                 odata[0] == DHCPV6_MSG_INFO_REQ))
 492                         msg = odata[0];
 493
 494         dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 495         return msg;
 496 }
 497
 498
 499 // Collect all advertised servers
 500 static int dhcpv6_handle_advert(_unused enum dhcpv6_msg orig,
 501                 const void *opt, const void *end)
 502 {
 503         uint16_t olen, otype;
 504         uint8_t *odata;
 505         struct dhcpv6_server_cand cand = {false, false, 0, 0, {0}};
 506
 507         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 508                 if (otype == DHCPV6_OPT_SERVERID && olen <= 130) {
 509                         memcpy(cand.duid, odata, olen);
 510                         cand.duid_len = olen;
 511                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 512                                 && odata[1] == DHCPV6_NoAddrsAvail) {
 513                         if (na_mode == IA_MODE_FORCE) {
 514                                 return -1;
 515                         } else {
 516                                 cand.has_noaddravail = true;
 517                                 cand.preference -= 1000;
 518                         }
 519                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 520                                 && odata[1] == DHCPV6_NoPrefixAvail) {
 521                         cand.preference -= 2000;
 522                 } else if (otype == DHCPV6_OPT_PREF && olen >= 1 &&
 523                                 cand.preference >= 0) {
 524                         cand.preference = odata[0];
 525                 } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
 526                         cand.wants_reconfigure = true;
 527                 } else if (otype == DHCPV6_OPT_IA_PD && request_prefix) {
 528                         struct dhcpv6_ia_hdr *h = (void*)odata;
 529                         uint8_t *oend = odata + olen, *d;
 530                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d) {
 531                                 if (otype == DHCPV6_OPT_IA_PREFIX)
 532                                         cand.preference += 2000;
 533                                 else if (otype == DHCPV6_OPT_STATUS &&
 534                                                 olen >= 2 && d[0] == 0 &&
 535                                                 d[1] == DHCPV6_NoPrefixAvail)
 536                                         cand.preference -= 2000;
 537                         }
 538                 }
 539         }
 540
 541         if (cand.duid_len > 0)
 542                 odhcp6c_add_state(STATE_SERVER_CAND, &cand, sizeof(cand));
 543
 544         return -1;
 545 }
 546
 547
 548 static int dhcpv6_commit_advert(void)
 549 {
 550         size_t cand_len;
 551         struct dhcpv6_server_cand *c = NULL, *cand =
 552                         odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
 553
 554         bool retry = false;
 555         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 556                 if (cand[i].has_noaddravail)
 557                         retry = true; // We want to try again
 558
 559                 if (!c || c->preference < cand[i].preference)
 560                         c = &cand[i];
 561         }
 562
 563         if (retry && na_mode == IA_MODE_TRY) {
 564                 // We give it a second try without the IA_NA
 565                 na_mode = IA_MODE_NONE;
 566                 return dhcpv6_request(DHCPV6_MSG_SOLICIT);
 567         }
 568
 569         if (c) {
 570                 uint16_t hdr[2] = {htons(DHCPV6_OPT_SERVERID),
 571                                 htons(c->duid_len)};
 572                 odhcp6c_add_state(STATE_SERVER_ID, hdr, sizeof(hdr));
 573                 odhcp6c_add_state(STATE_SERVER_ID, c->duid, c->duid_len);
 574                 accept_reconfig = c->wants_reconfigure;
 575         }
 576
 577         odhcp6c_clear_state(STATE_SERVER_CAND);
 578
 579         if (!c)
 580                 return -1;
 581         else if (request_prefix || na_mode != IA_MODE_NONE)
 582                 return DHCPV6_STATEFUL;
 583         else
 584                 return DHCPV6_STATELESS;
 585 }
 586
 587
 588 static int dhcpv6_handle_rebind_reply(enum dhcpv6_msg orig,
 589                 const void *opt, const void *end)
 590 {
 591         dhcpv6_handle_advert(orig, opt, end);
 592         if (dhcpv6_commit_advert() < 0) {
 593                 dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 594                 return -1;
 595         }
 596
 597         return dhcpv6_handle_reply(orig, opt, end);
 598 }
 599
 600
 601 static int dhcpv6_handle_reply(enum dhcpv6_msg orig,
 602                 const void *opt, const void *end)
 603 {
 604         uint8_t *odata;
 605         uint16_t otype, olen;
 606
 607         static time_t last_update = 0;
 608         time_t now = odhcp6c_get_milli_time() / 1000;
 609
 610         uint32_t elapsed = now - last_update;
 611         odhcp6c_expire();
 612
 613         if (orig == DHCPV6_MSG_UNKNOWN) {
 614                 t1 -= elapsed;
 615                 t2 -= elapsed;
 616                 t3 -= elapsed;
 617
 618                 if (t1 < 0)
 619                         t1 = 0;
 620
 621                 if (t2 < 0)
 622                         t2 = 0;
 623
 624                 if (t3 < 0)
 625                         t3 = 0;
 626         } else {
 627                 t1 = t2 = t3 = UINT32_MAX;
 628         }
 629
 630         if (opt) {
 631                 odhcp6c_clear_state(STATE_DNS);
 632                 odhcp6c_clear_state(STATE_SEARCH);
 633                 odhcp6c_clear_state(STATE_SNTP_IP);
 634                 odhcp6c_clear_state(STATE_SNTP_FQDN);
 635                 odhcp6c_clear_state(STATE_SIP_IP);
 636                 odhcp6c_clear_state(STATE_SIP_FQDN);
 637         }
 638
 639         // Parse and find all matching IAs
 640         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 641                 if ((otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA)
 642                                 && olen > sizeof(struct dhcpv6_ia_hdr)) {
 643                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 644                         uint32_t l_t1 = ntohl(ia_hdr->t1);
 645                         uint32_t l_t2 = ntohl(ia_hdr->t2);
 646
 647                         // Test ID and T1-T2 validity
 648                         if (ia_hdr->iaid != 1 || l_t2 < l_t1)
 649                                 continue;
 650
 651                         bool error = false;
 652                         uint16_t stype, slen;
 653                         uint8_t *sdata;
 654                         // Test status and bail if error
 655                         dhcpv6_for_each_option(&ia_hdr[1], odata + olen,
 656                                         stype, slen, sdata)
 657                                 if (stype == DHCPV6_OPT_STATUS && slen >= 2 &&
 658                                                 (sdata[0] || sdata[1]))
 659                                         error = true;
 660
 661                         if (error)
 662                                 continue;
 663
 664                         // Update times
 665                         if (l_t1 > 0 && t1 > l_t1)
 666                                 t1 = l_t1;
 667
 668                         if (l_t2 > 0 && t2 > l_t2)
 669                                 t2 = l_t2;
 670
 671                         uint32_t n = dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 672
 673                         if (n < t1)
 674                                 t1 = n;
 675
 676                         if (n < t2)
 677                                 t2 = n;
 678
 679                         if (n < t3)
 680                                 t3 = n;
 681
 682                         if (t2 >= t3)
 683                                 t2 = 8 * t3 / 10;
 684
 685                         if (t1 >= t2)
 686                                 t1 = 5 * t2 / 8;
 687
 688                 } else if (otype == DHCPV6_OPT_DNS_SERVERS) {
 689                         if (olen % 16 == 0)
 690                                 odhcp6c_add_state(STATE_DNS, odata, olen);
 691                 } else if (otype == DHCPV6_OPT_DNS_DOMAIN) {
 692                         odhcp6c_add_state(STATE_SEARCH, odata, olen);
 693                 } else if (otype == DHCPV6_OPT_NTP_SERVER) {
 694                         uint16_t stype, slen;
 695                         uint8_t *sdata;
 696                         // Test status and bail if error
 697                         dhcpv6_for_each_option(odata, odata + olen,
 698                                         stype, slen, sdata) {
 699                                 if (slen == 16 && (stype == NTP_MC_ADDR ||
 700                                                 stype == NTP_SRV_ADDR))
 701                                         odhcp6c_add_state(STATE_SNTP_IP,
 702                                                         sdata, slen);
 703                                 else if (slen > 0 && stype == NTP_SRV_FQDN)
 704                                         odhcp6c_add_state(STATE_SNTP_FQDN,
 705                                                         sdata, slen);
 706                         }
 707                 } else if (otype == DHCPV6_OPT_SIP_SERVER_A) {
 708                         if (olen == 16)
 709                                 odhcp6c_add_state(STATE_SIP_IP, odata, olen);
 710                 } else if (otype == DHCPV6_OPT_SIP_SERVER_D) {
 711                         odhcp6c_add_state(STATE_SIP_FQDN, odata, olen);
 712                 } else if (otype == DHCPV6_OPT_INFO_REFRESH && olen >= 4) {
 713                         uint32_t refresh = ntohl(*((uint32_t*)odata));
 714                         if (refresh < (uint32_t)t1)
 715                                 t1 = refresh;
 716                 } else if (otype != DHCPV6_OPT_CLIENTID &&
 717                                 otype != DHCPV6_OPT_SERVERID) {
 718                         odhcp6c_add_state(STATE_CUSTOM_OPTS,
 719                                         &odata[-4], olen + 4);
 720                 }
 721         }
 722
 723         return true;
 724 }
 725
 726
 727 static uint32_t dhcpv6_parse_ia(void *opt, void *end)
 728 {
 729         uint32_t timeout = UINT32_MAX; // Minimum timeout
 730         uint16_t otype, olen;
 731         uint8_t *odata;
 732
 733         // Update address IA
 734         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 735           struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT,
 736                                         0, 0, IN6ADDR_ANY_INIT, 0, 0, 0};
 737
 738                 if (otype == DHCPV6_OPT_IA_PREFIX) {
 739                         struct dhcpv6_ia_prefix *prefix = (void*)&odata[-4];
 740                         if (olen + 4U < sizeof(*prefix))
 741                                 continue;
 742
 743                         entry.valid = ntohl(prefix->valid);
 744                         entry.preferred = ntohl(prefix->preferred);
 745
 746                         if (entry.preferred > entry.valid)
 747                                 continue;
 748
 749                         entry.length = prefix->prefix;
 750                         entry.target = prefix->addr;
 751                         uint16_t stype, slen;
 752                         uint8_t *sdata;
 753
 754                         // Find prefix class, if any
 755                         dhcpv6_for_each_option(odata, odata + olen,
 756                                                stype, slen, sdata)
 757                           if (stype == DHCPV6_OPT_PREFIX_CLASS && slen == 2)
 758                             entry.prefix_class = ntohs(*((uint16_t*)sdata));
 759
 760                         odhcp6c_update_entry(STATE_IA_PD, &entry);
 761                 } else if (otype == DHCPV6_OPT_IA_ADDR) {
 762                         struct dhcpv6_ia_addr *addr = (void*)&odata[-4];
 763                         if (olen + 4U < sizeof(*addr))
 764                                 continue;
 765
 766                         entry.preferred = ntohl(addr->preferred);
 767                         entry.valid = ntohl(addr->valid);
 768
 769                         if (entry.preferred > entry.valid)
 770                                 continue;
 771
 772                         entry.length = 128;
 773                         entry.target = addr->addr;
 774
 775                         odhcp6c_update_entry(STATE_IA_NA, &entry);
 776                 }
 777
 778                 if (entry.valid > 0 && timeout > entry.valid)
 779                         timeout = entry.valid;
 780         }
 781
 782         return timeout;
 783 }