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 #include "md5.h"
  36
  37
  38 #define ALL_DHCPV6_RELAYS {{{0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\
  39                 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x02}}}
  40 #define DHCPV6_CLIENT_PORT 546
  41 #define DHCPV6_SERVER_PORT 547
  42 #define DHCPV6_DUID_LLADDR 3
  43 #define DHCPV6_REQ_DELAY 1
  44
  45
  46 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
  47                 const uint8_t transaction[3], enum dhcpv6_msg type);
  48
  49 static uint32_t dhcpv6_parse_ia(void *opt, void *end);
  50
  51 static reply_handler dhcpv6_handle_reply;
  52 static reply_handler dhcpv6_handle_advert;
  53 static reply_handler dhcpv6_handle_rebind_reply;
  54 static reply_handler dhcpv6_handle_reconfigure;
  55 static int dhcpv6_commit_advert(void);
  56
  57
  58
  59 // RFC 3315 - 5.5 Timeout and Delay values
  60 static struct dhcpv6_retx dhcpv6_retx[_DHCPV6_MSG_MAX] = {
  61         [DHCPV6_MSG_UNKNOWN] = {false, 1, 120, "<POLL>",
  62                         dhcpv6_handle_reconfigure, NULL},
  63         [DHCPV6_MSG_SOLICIT] = {true, 1, 3600, "SOLICIT",
  64                         dhcpv6_handle_advert, dhcpv6_commit_advert},
  65         [DHCPV6_MSG_REQUEST] = {true, 30, 10, "REQUEST",
  66                         dhcpv6_handle_reply, NULL},
  67         [DHCPV6_MSG_RENEW] = {false, 10, 600, "RENEW",
  68                         dhcpv6_handle_reply, NULL},
  69         [DHCPV6_MSG_REBIND] = {false, 10, 600, "REBIND",
  70                         dhcpv6_handle_rebind_reply, NULL},
  71         [DHCPV6_MSG_RELEASE] = {false, 1, 600, "RELEASE", NULL, NULL},
  72         [DHCPV6_MSG_DECLINE] = {false, 1, 3, "DECLINE", NULL, NULL},
  73         [DHCPV6_MSG_INFO_REQ] = {true, 1, 120, "INFOREQ",
  74                         dhcpv6_handle_reply, NULL},
  75 };
  76
  77
  78 // Sockets
  79 static int sock = -1;
  80 static int ifindex = -1;
  81 static int64_t t1 = 0, t2 = 0, t3 = 0;
  82
  83 // IA states
  84 static int request_prefix = -1;
  85 static enum odhcp6c_ia_mode na_mode = IA_MODE_NONE;
  86 static bool accept_reconfig = false;
  87
  88 // Reconfigure key
  89 static uint8_t reconf_key[16];
  90
  91
  92
  93 int init_dhcpv6(const char *ifname, int request_pd)
  94 {
  95         request_prefix = request_pd;
  96
  97         sock = socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
  98
  99         // Detect interface
 100         struct ifreq ifr;
 101         strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
 102         if (ioctl(sock, SIOCGIFINDEX, &ifr))
 103                 return -1;
 104         ifindex = ifr.ifr_ifindex;
 105
 106         // Create client DUID
 107         size_t client_id_len;
 108         odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 109         if (client_id_len == 0) {
 110                 ioctl(sock, SIOCGIFHWADDR, &ifr);
 111                 uint8_t duid[14] = {0, DHCPV6_OPT_CLIENTID, 0, 10, 0,
 112                                 DHCPV6_DUID_LLADDR, 0, 1};
 113                 memcpy(&duid[8], ifr.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
 114
 115                 uint8_t zero[ETHER_ADDR_LEN] = {0, 0, 0, 0, 0, 0};
 116                 struct ifreq ifs[100], *ifp, *ifend;
 117                 struct ifconf ifc;
 118                 ifc.ifc_req = ifs;
 119                 ifc.ifc_len = sizeof(ifs);
 120
 121                 if (!memcmp(&duid[8], zero, ETHER_ADDR_LEN) &&
 122                                 ioctl(sock, SIOCGIFCONF, &ifc) >= 0) {
 123                         // If our interface doesn't have an address...
 124                         ifend = ifs + (ifc.ifc_len / sizeof(struct ifreq));
 125                         for (ifp = ifc.ifc_req; ifp < ifend &&
 126                                         !memcmp(&duid[8], zero, 6); ifp++) {
 127                                 memcpy(ifr.ifr_name, ifp->ifr_name,
 128                                                 sizeof(ifr.ifr_name));
 129                                 ioctl(sock, SIOCGIFHWADDR, &ifr);
 130                                 memcpy(&duid[8], ifr.ifr_hwaddr.sa_data,
 131                                                 ETHER_ADDR_LEN);
 132                         }
 133                 }
 134
 135                 odhcp6c_add_state(STATE_CLIENT_ID, duid, sizeof(duid));
 136         }
 137
 138         // Create ORO
 139         uint16_t oro[] = {htons(DHCPV6_OPT_DNS_SERVERS),
 140                         htons(DHCPV6_OPT_DNS_DOMAIN),
 141                         htons(DHCPV6_OPT_NTP_SERVER),
 142                         htons(DHCPV6_OPT_SIP_SERVER_A),
 143                         htons(DHCPV6_OPT_SIP_SERVER_D),
 144                         htons(DHCPV6_OPT_PD_EXCLUDE)};
 145         odhcp6c_add_state(STATE_ORO, oro, sizeof(oro));
 146
 147
 148         // Configure IPv6-options
 149         int val = 1;
 150         setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val));
 151         setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
 152         setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
 153
 154         struct sockaddr_in6 client_addr = { .sin6_family = AF_INET6,
 155                 .sin6_port = htons(DHCPV6_CLIENT_PORT), .sin6_flowinfo = 0 };
 156         if (bind(sock, (struct sockaddr*)&client_addr, sizeof(client_addr)))
 157                 return -1;
 158
 159         return 0;
 160 }
 161
 162
 163 void dhcpv6_set_ia_na_mode(enum odhcp6c_ia_mode mode)
 164 {
 165         na_mode = mode;
 166 }
 167
 168
 169 static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
 170 {
 171         // Build FQDN
 172         char fqdn_buf[256];
 173         gethostname(fqdn_buf, sizeof(fqdn_buf));
 174         struct {
 175                 uint16_t type;
 176                 uint16_t len;
 177                 uint8_t flags;
 178                 uint8_t data[256];
 179         } fqdn;
 180         size_t fqdn_len = 5 + dn_comp(fqdn_buf, fqdn.data,
 181                         sizeof(fqdn.data), NULL, NULL);
 182         fqdn.type = htons(DHCPV6_OPT_FQDN);
 183         fqdn.len = htons(fqdn_len - 4);
 184         fqdn.flags = 0;
 185
 186
 187         // Build Client ID
 188         size_t cl_id_len;
 189         void *cl_id = odhcp6c_get_state(STATE_CLIENT_ID, &cl_id_len);
 190
 191         // Get Server ID
 192         size_t srv_id_len;
 193         void *srv_id = odhcp6c_get_state(STATE_SERVER_ID, &srv_id_len);
 194
 195         // Build IA_PDs
 196         size_t ia_pd_entries, ia_pd_len = 0;
 197         struct odhcp6c_entry *e = odhcp6c_get_state(STATE_IA_PD, &ia_pd_entries);
 198         ia_pd_entries /= sizeof(*e);
 199         struct dhcpv6_ia_hdr hdr_ia_pd = {
 200                 htons(DHCPV6_OPT_IA_PD),
 201                 htons(sizeof(hdr_ia_pd) - 4),
 202                 1, 0, 0
 203         };
 204
 205
 206         uint8_t *ia_pd = alloca(ia_pd_entries * (sizeof(struct dhcpv6_ia_prefix) + 10));
 207         for (size_t i = 0; i < ia_pd_entries; ++i) {
 208                 uint8_t ex_len = 0;
 209                 if (e[i].priority > 0)
 210                         ex_len = ((e[i].priority - e[i].length - 1) / 8) + 6;
 211
 212                 struct dhcpv6_ia_prefix p = {
 213                         .type = htons(DHCPV6_OPT_IA_PREFIX),
 214                         .len = htons(sizeof(p) - 4U + ex_len),
 215                         .prefix = e[i].length,
 216                         .addr = e[i].target
 217                 };
 218
 219                 memcpy(ia_pd + ia_pd_len, &p, sizeof(p));
 220                 ia_pd_len += sizeof(p);
 221
 222                 if (ex_len) {
 223                         ia_pd[ia_pd_len++] = 0;
 224                         ia_pd[ia_pd_len++] = DHCPV6_OPT_PD_EXCLUDE;
 225                         ia_pd[ia_pd_len++] = 0;
 226                         ia_pd[ia_pd_len++] = ex_len - 4;
 227                         ia_pd[ia_pd_len++] = e[i].priority;
 228
 229                         uint32_t excl = ntohl(e[i].router.s6_addr32[1]);
 230                         excl >>= (64 - e[i].priority);
 231                         excl <<= 8 - ((e[i].priority - e[i].length) % 8);
 232
 233                         for (size_t i = ex_len - 5; i > 0; --i, excl >>= 8)
 234                                 ia_pd[ia_pd_len + i] = excl & 0xff;
 235                         ia_pd_len += ex_len - 5;
 236                 }
 237         }
 238
 239         struct dhcpv6_ia_prefix pref = {
 240                 .type = htons(DHCPV6_OPT_IA_PREFIX),
 241                 .len = htons(25), .prefix = request_prefix
 242         };
 243         if (request_prefix > 0 && ia_pd_len == 0 &&
 244                         (type == DHCPV6_MSG_SOLICIT ||
 245                         type == DHCPV6_MSG_REQUEST)) {
 246                 ia_pd = (uint8_t*)&pref;
 247                 ia_pd_len = sizeof(pref);
 248         }
 249         hdr_ia_pd.len = htons(ntohs(hdr_ia_pd.len) + ia_pd_len);
 250
 251         // Build IA_NAs
 252         size_t ia_na_entries, ia_na_len = 0;
 253         void *ia_na = NULL;
 254         e = odhcp6c_get_state(STATE_IA_NA, &ia_na_entries);
 255         ia_na_entries /= sizeof(*e);
 256
 257         struct dhcpv6_ia_hdr hdr_ia_na = {
 258                 htons(DHCPV6_OPT_IA_NA),
 259                 htons(sizeof(hdr_ia_na) - 4),
 260                 1, 0, 0
 261         };
 262
 263         struct dhcpv6_ia_addr pa[ia_na_entries];
 264         for (size_t i = 0; i < ia_na_entries; ++i) {
 265                 pa[i].type = htons(DHCPV6_OPT_IA_ADDR);
 266                 pa[i].len = htons(sizeof(pa[i]) - 4U);
 267                 pa[i].addr = e[i].target;
 268                 pa[i].preferred = 0;
 269                 pa[i].valid = 0;
 270         }
 271
 272         ia_na = pa;
 273         ia_na_len = sizeof(pa);
 274         hdr_ia_na.len = htons(ntohs(hdr_ia_na.len) + ia_na_len);
 275
 276         // Reconfigure Accept
 277         struct {
 278                 uint16_t type;
 279                 uint16_t length;
 280         } reconf_accept = {htons(DHCPV6_OPT_RECONF_ACCEPT), 0};
 281
 282         // Request Information Refresh
 283         uint16_t oro_refresh = htons(DHCPV6_OPT_INFO_REFRESH);
 284
 285         // Prepare Header
 286         size_t oro_len;
 287         void *oro = odhcp6c_get_state(STATE_ORO, &oro_len);
 288         struct {
 289                 uint8_t type;
 290                 uint8_t trid[3];
 291                 uint16_t elapsed_type;
 292                 uint16_t elapsed_len;
 293                 uint16_t elapsed_value;
 294                 uint16_t oro_type;
 295                 uint16_t oro_len;
 296         } hdr = {
 297                 type, {trid[0], trid[1], trid[2]},
 298                 htons(DHCPV6_OPT_ELAPSED), htons(2),
 299                         htons((ecs > 0xffff) ? 0xffff : ecs),
 300                 htons(DHCPV6_OPT_ORO), htons(oro_len),
 301         };
 302
 303         struct iovec iov[] = {
 304                 {&hdr, sizeof(hdr)},
 305                 {oro, oro_len},
 306                 {&oro_refresh, 0},
 307                 {cl_id, cl_id_len},
 308                 {srv_id, srv_id_len},
 309                 {&reconf_accept, 0},
 310                 {&fqdn, fqdn_len},
 311                 {&hdr_ia_na, sizeof(hdr_ia_na)},
 312                 {ia_na, ia_na_len},
 313                 {&hdr_ia_pd, sizeof(hdr_ia_pd)},
 314                 {ia_pd, ia_pd_len},
 315         };
 316
 317         size_t cnt = ARRAY_SIZE(iov);
 318         if (type == DHCPV6_MSG_INFO_REQ) {
 319                 cnt = 5;
 320                 iov[2].iov_len = sizeof(oro_refresh);
 321                 hdr.oro_len = htons(oro_len + sizeof(oro_refresh));
 322         } else if (!request_prefix) {
 323                 cnt = 9;
 324         }
 325
 326         // Disable IAs if not used
 327         if (type == DHCPV6_MSG_SOLICIT) {
 328                 iov[5].iov_len = sizeof(reconf_accept);
 329         } else if (type != DHCPV6_MSG_REQUEST) {
 330                 if (ia_na_len == 0)
 331                         iov[7].iov_len = 0;
 332                 if (ia_pd_len == 0)
 333                         iov[9].iov_len = 0;
 334         }
 335
 336         if (na_mode == IA_MODE_NONE)
 337                 iov[7].iov_len = 0;
 338
 339         struct sockaddr_in6 srv = {AF_INET6, htons(DHCPV6_SERVER_PORT),
 340                 0, ALL_DHCPV6_RELAYS, ifindex};
 341         struct msghdr msg = {&srv, sizeof(srv), iov, cnt, NULL, 0, 0};
 342
 343         sendmsg(sock, &msg, 0);
 344 }
 345
 346
 347 static int64_t dhcpv6_rand_delay(int64_t time)
 348 {
 349         int random;
 350         odhcp6c_random(&random, sizeof(random));
 351         return (time * (random % 1000)) / 10000;
 352 }
 353
 354
 355 int dhcpv6_request(enum dhcpv6_msg type)
 356 {
 357         uint8_t buf[1536];
 358         uint32_t timeout = UINT32_MAX;
 359         struct dhcpv6_retx *retx = &dhcpv6_retx[type];
 360
 361         if (retx->delay) {
 362                 struct timespec ts = {0, 0};
 363                 ts.tv_nsec = dhcpv6_rand_delay(10 * DHCPV6_REQ_DELAY);
 364                 nanosleep(&ts, NULL);
 365         }
 366
 367         if (type == DHCPV6_MSG_RELEASE || type == DHCPV6_MSG_DECLINE)
 368                 timeout = 3;
 369         else if (type == DHCPV6_MSG_UNKNOWN)
 370                 timeout = t1;
 371         else if (type == DHCPV6_MSG_RENEW)
 372                 timeout = t2 - t1;
 373         else if (type == DHCPV6_MSG_REBIND)
 374                 timeout = t3 - t2;
 375
 376         if (timeout == 0)
 377                 return -1;
 378
 379         syslog(LOG_NOTICE, "Sending %s (timeout %us)", retx->name, timeout);
 380
 381         uint64_t start = odhcp6c_get_milli_time(), round_start = start, elapsed;
 382
 383         // Generate transaction ID
 384         uint8_t trid[3] = {0, 0, 0};
 385         if (type != DHCPV6_MSG_UNKNOWN)
 386                 odhcp6c_random(trid, sizeof(trid));
 387         ssize_t len = -1;
 388         int64_t rto = 0;
 389
 390         do {
 391                 rto = (rto == 0) ? (retx->init_timeo * 1000 +
 392                                 dhcpv6_rand_delay(retx->init_timeo * 1000)) :
 393                                 (2 * rto + dhcpv6_rand_delay(rto));
 394
 395                 if (rto >= retx->max_timeo * 1000)
 396                         rto = retx->max_timeo * 1000 +
 397                                 dhcpv6_rand_delay(retx->max_timeo * 1000);
 398
 399                 // Calculate end for this round and elapsed time
 400                 uint64_t round_end = round_start + rto;
 401                 elapsed = round_start - start;
 402
 403                 // Don't wait too long
 404                 if (round_end - start > timeout * 1000)
 405                         round_end = timeout * 1000 + start;
 406
 407                 // Built and send package
 408                 if (type != DHCPV6_MSG_UNKNOWN)
 409                         dhcpv6_send(type, trid, elapsed / 10);
 410
 411                 // Receive rounds
 412                 for (; len < 0 && round_start < round_end;
 413                                 round_start = odhcp6c_get_milli_time()) {
 414                         // Check for pending signal
 415                         if (odhcp6c_signal_process())
 416                                 return -1;
 417
 418                         // Set timeout for receiving
 419                         uint64_t t = round_end - round_start;
 420                         struct timeval timeout = {t / 1000, (t % 1000) * 1000};
 421                         setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
 422                                         &timeout, sizeof(timeout));
 423
 424                         // Receive cycle
 425                         len = recv(sock, buf, sizeof(buf), 0);
 426
 427                         if (!dhcpv6_response_is_valid(buf, len, trid, type))
 428                                 len = -1;
 429
 430                         if (len > 0) {
 431                                 uint8_t *opt = &buf[4];
 432                                 uint8_t *opt_end = opt + len - 4;
 433
 434                                 round_start = odhcp6c_get_milli_time();
 435                                 elapsed = round_start - start;
 436                                 syslog(LOG_NOTICE, "Got a valid reply after "
 437                                                 "%ums", (unsigned)elapsed);
 438
 439                                 if (retx->handler_reply)
 440                                         len = retx->handler_reply(
 441                                                         type, opt, opt_end);
 442
 443                                 if (round_end - round_start > 1000)
 444                                         round_end = 1000 + round_start;
 445                         }
 446                 }
 447
 448                 // Allow
 449                 if (retx->handler_finish)
 450                         len = retx->handler_finish();
 451         } while (len < 0 && elapsed / 1000 < timeout);
 452
 453         return len;
 454 }
 455
 456
 457 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
 458                 const uint8_t transaction[3], enum dhcpv6_msg type)
 459 {
 460         const struct dhcpv6_header *rep = buf;
 461         if (len < (ssize_t)sizeof(*rep) || memcmp(rep->tr_id,
 462                         transaction, sizeof(rep->tr_id)))
 463                 return false; // Invalid reply
 464
 465         if (type == DHCPV6_MSG_SOLICIT) {
 466                 if (rep->msg_type != DHCPV6_MSG_ADVERT &&
 467                                 rep->msg_type != DHCPV6_MSG_REPLY)
 468                         return false;
 469         } else if (type == DHCPV6_MSG_UNKNOWN) {
 470                 if (!accept_reconfig || rep->msg_type != DHCPV6_MSG_RECONF)
 471                         return false;
 472         } else if (rep->msg_type != DHCPV6_MSG_REPLY) {
 473                 return false;
 474         }
 475
 476         uint8_t *end = ((uint8_t*)buf) + len, *odata;
 477         uint16_t otype, olen;
 478         bool clientid_ok = false, serverid_ok = false, rcauth_ok = false;
 479
 480         size_t client_id_len, server_id_len;
 481         void *client_id = odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 482         void *server_id = odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 483
 484         dhcpv6_for_each_option(&rep[1], end, otype, olen, odata) {
 485                 if (otype == DHCPV6_OPT_CLIENTID) {
 486                         clientid_ok = (olen + 4U == client_id_len) && !memcmp(
 487                                         &odata[-4], client_id, client_id_len);
 488                 } else if (otype == DHCPV6_OPT_SERVERID) {
 489                         serverid_ok = (olen + 4U == server_id_len) && !memcmp(
 490                                         &odata[-4], server_id, server_id_len);
 491                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 492                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 493                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 494                         if (r->protocol != 3 || r->algorithm != 1 || r->reconf_type != 2)
 495                                 continue;
 496
 497                         md5_state_t md5;
 498                         uint8_t serverhash[16], secretbytes[16], hash[16];
 499                         memcpy(serverhash, r->key, sizeof(serverhash));
 500                         memset(r->key, 0, sizeof(r->key));
 501                         memcpy(secretbytes, reconf_key, sizeof(secretbytes));
 502
 503                         for (size_t i = 0; i < sizeof(secretbytes); ++i)
 504                                 secretbytes[i] ^= 0x36;
 505
 506                         md5_init(&md5);
 507                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 508                         md5_append(&md5, buf, len);
 509                         md5_finish(&md5, hash);
 510
 511                         for (size_t i = 0; i < sizeof(secretbytes); ++i) {
 512                                 secretbytes[i] ^= 0x36;
 513                                 secretbytes[i] ^= 0x5c;
 514                         }
 515
 516                         md5_init(&md5);
 517                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 518                         md5_append(&md5, hash, 16);
 519                         md5_finish(&md5, hash);
 520
 521                         rcauth_ok = !memcmp(hash, serverhash, sizeof(hash));
 522                 }
 523         }
 524
 525         if (rep->msg_type == DHCPV6_MSG_RECONF && !rcauth_ok)
 526                 return false;
 527
 528         return clientid_ok && (serverid_ok || server_id_len == 0);
 529 }
 530
 531
 532 int dhcpv6_poll_reconfigure(void)
 533 {
 534         int ret = dhcpv6_request(DHCPV6_MSG_UNKNOWN);
 535         if (ret != -1)
 536                 ret = dhcpv6_request(ret);
 537
 538         return ret;
 539 }
 540
 541
 542 static int dhcpv6_handle_reconfigure(_unused enum dhcpv6_msg orig,
 543                 const void *opt, const void *end)
 544 {
 545         // TODO: should verify the reconfigure message
 546         uint16_t otype, olen;
 547         uint8_t *odata, msg = DHCPV6_MSG_RENEW;
 548         dhcpv6_for_each_option(opt, end, otype, olen, odata)
 549                 if (otype == DHCPV6_OPT_RECONF_MESSAGE && olen == 1 && (
 550                                 odata[0] == DHCPV6_MSG_RENEW ||
 551                                 odata[0] == DHCPV6_MSG_INFO_REQ))
 552                         msg = odata[0];
 553
 554         dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 555         return msg;
 556 }
 557
 558
 559 // Collect all advertised servers
 560 static int dhcpv6_handle_advert(_unused enum dhcpv6_msg orig,
 561                 const void *opt, const void *end)
 562 {
 563         uint16_t olen, otype;
 564         uint8_t *odata;
 565         struct dhcpv6_server_cand cand = {false, false, 0, 0, {0}};
 566
 567         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 568                 if (otype == DHCPV6_OPT_SERVERID && olen <= 130) {
 569                         memcpy(cand.duid, odata, olen);
 570                         cand.duid_len = olen;
 571                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 572                                 && odata[1] == DHCPV6_NoAddrsAvail) {
 573                         if (na_mode == IA_MODE_FORCE) {
 574                                 return -1;
 575                         } else {
 576                                 cand.has_noaddravail = true;
 577                                 cand.preference -= 1000;
 578                         }
 579                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 580                                 && odata[1] == DHCPV6_NoPrefixAvail) {
 581                         cand.preference -= 2000;
 582                 } else if (otype == DHCPV6_OPT_PREF && olen >= 1 &&
 583                                 cand.preference >= 0) {
 584                         cand.preference = odata[0];
 585                 } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
 586                         cand.wants_reconfigure = true;
 587                 } else if (otype == DHCPV6_OPT_IA_PD && request_prefix) {
 588                         struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
 589                         uint8_t *oend = odata + olen, *d;
 590                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d) {
 591                                 if (otype == DHCPV6_OPT_IA_PREFIX)
 592                                         cand.preference += 2000;
 593                                 else if (otype == DHCPV6_OPT_STATUS &&
 594                                                 olen >= 2 && d[0] == 0 &&
 595                                                 d[1] == DHCPV6_NoPrefixAvail)
 596                                         cand.preference -= 2000;
 597                         }
 598                 }
 599         }
 600
 601         if (cand.duid_len > 0)
 602                 odhcp6c_add_state(STATE_SERVER_CAND, &cand, sizeof(cand));
 603
 604         return -1;
 605 }
 606
 607
 608 static int dhcpv6_commit_advert(void)
 609 {
 610         size_t cand_len;
 611         struct dhcpv6_server_cand *c = NULL, *cand =
 612                         odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
 613
 614         bool retry = false;
 615         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 616                 if (cand[i].has_noaddravail)
 617                         retry = true; // We want to try again
 618
 619                 if (!c || c->preference < cand[i].preference)
 620                         c = &cand[i];
 621         }
 622
 623         if (retry && na_mode == IA_MODE_TRY) {
 624                 // We give it a second try without the IA_NA
 625                 na_mode = IA_MODE_NONE;
 626                 return dhcpv6_request(DHCPV6_MSG_SOLICIT);
 627         }
 628
 629         if (c) {
 630                 uint16_t hdr[2] = {htons(DHCPV6_OPT_SERVERID),
 631                                 htons(c->duid_len)};
 632                 odhcp6c_add_state(STATE_SERVER_ID, hdr, sizeof(hdr));
 633                 odhcp6c_add_state(STATE_SERVER_ID, c->duid, c->duid_len);
 634                 accept_reconfig = c->wants_reconfigure;
 635         }
 636
 637         odhcp6c_clear_state(STATE_SERVER_CAND);
 638
 639         if (!c)
 640                 return -1;
 641         else if (request_prefix || na_mode != IA_MODE_NONE)
 642                 return DHCPV6_STATEFUL;
 643         else
 644                 return DHCPV6_STATELESS;
 645 }
 646
 647
 648 static int dhcpv6_handle_rebind_reply(enum dhcpv6_msg orig,
 649                 const void *opt, const void *end)
 650 {
 651         dhcpv6_handle_advert(orig, opt, end);
 652         if (dhcpv6_commit_advert() < 0) {
 653                 dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 654                 return -1;
 655         }
 656
 657         return dhcpv6_handle_reply(orig, opt, end);
 658 }
 659
 660
 661 static int dhcpv6_handle_reply(enum dhcpv6_msg orig,
 662                 const void *opt, const void *end)
 663 {
 664         uint8_t *odata;
 665         uint16_t otype, olen;
 666
 667         static time_t last_update = 0;
 668         time_t now = odhcp6c_get_milli_time() / 1000;
 669
 670         uint32_t elapsed = now - last_update;
 671         odhcp6c_expire();
 672
 673         if (orig == DHCPV6_MSG_UNKNOWN) {
 674                 t1 -= elapsed;
 675                 t2 -= elapsed;
 676                 t3 -= elapsed;
 677
 678                 if (t1 < 0)
 679                         t1 = 0;
 680
 681                 if (t2 < 0)
 682                         t2 = 0;
 683
 684                 if (t3 < 0)
 685                         t3 = 0;
 686         } else {
 687                 t1 = t2 = t3 = UINT32_MAX;
 688         }
 689
 690         if (opt) {
 691                 odhcp6c_clear_state(STATE_DNS);
 692                 odhcp6c_clear_state(STATE_SEARCH);
 693                 odhcp6c_clear_state(STATE_SNTP_IP);
 694                 odhcp6c_clear_state(STATE_SNTP_FQDN);
 695                 odhcp6c_clear_state(STATE_SIP_IP);
 696                 odhcp6c_clear_state(STATE_SIP_FQDN);
 697         }
 698
 699         // Parse and find all matching IAs
 700         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 701                 if ((otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA)
 702                                 && olen > sizeof(struct dhcpv6_ia_hdr)) {
 703                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 704                         uint32_t l_t1 = ntohl(ia_hdr->t1);
 705                         uint32_t l_t2 = ntohl(ia_hdr->t2);
 706
 707                         // Test ID and T1-T2 validity
 708                         if (ia_hdr->iaid != 1 || l_t2 < l_t1)
 709                                 continue;
 710
 711                         bool error = false;
 712                         uint16_t stype, slen;
 713                         uint8_t *sdata;
 714                         // Test status and bail if error
 715                         dhcpv6_for_each_option(&ia_hdr[1], odata + olen,
 716                                         stype, slen, sdata)
 717                                 if (stype == DHCPV6_OPT_STATUS && slen >= 2 &&
 718                                                 (sdata[0] || sdata[1]))
 719                                         error = true;
 720
 721                         if (error)
 722                                 continue;
 723
 724                         // Update times
 725                         if (l_t1 > 0 && t1 > l_t1)
 726                                 t1 = l_t1;
 727
 728                         if (l_t2 > 0 && t2 > l_t2)
 729                                 t2 = l_t2;
 730
 731                         uint32_t n = dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 732
 733                         if (n < t1)
 734                                 t1 = n;
 735
 736                         if (n < t2)
 737                                 t2 = n;
 738
 739                         if (n < t3)
 740                                 t3 = n;
 741
 742                         if (t2 >= t3)
 743                                 t2 = 8 * t3 / 10;
 744
 745                         if (t1 >= t2)
 746                                 t1 = 5 * t2 / 8;
 747
 748                 } else if (otype == DHCPV6_OPT_DNS_SERVERS) {
 749                         if (olen % 16 == 0)
 750                                 odhcp6c_add_state(STATE_DNS, odata, olen);
 751                 } else if (otype == DHCPV6_OPT_DNS_DOMAIN) {
 752                         odhcp6c_add_state(STATE_SEARCH, odata, olen);
 753                 } else if (otype == DHCPV6_OPT_NTP_SERVER) {
 754                         uint16_t stype, slen;
 755                         uint8_t *sdata;
 756                         // Test status and bail if error
 757                         dhcpv6_for_each_option(odata, odata + olen,
 758                                         stype, slen, sdata) {
 759                                 if (slen == 16 && (stype == NTP_MC_ADDR ||
 760                                                 stype == NTP_SRV_ADDR))
 761                                         odhcp6c_add_state(STATE_SNTP_IP,
 762                                                         sdata, slen);
 763                                 else if (slen > 0 && stype == NTP_SRV_FQDN)
 764                                         odhcp6c_add_state(STATE_SNTP_FQDN,
 765                                                         sdata, slen);
 766                         }
 767                 } else if (otype == DHCPV6_OPT_SIP_SERVER_A) {
 768                         if (olen == 16)
 769                                 odhcp6c_add_state(STATE_SIP_IP, odata, olen);
 770                 } else if (otype == DHCPV6_OPT_SIP_SERVER_D) {
 771                         odhcp6c_add_state(STATE_SIP_FQDN, odata, olen);
 772                 } else if (otype == DHCPV6_OPT_INFO_REFRESH && olen >= 4) {
 773                         uint32_t refresh = ntohl(*((uint32_t*)odata));
 774                         if (refresh < (uint32_t)t1)
 775                                 t1 = refresh;
 776                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 777                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 778                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 779                         if (r->protocol == 3 && r->algorithm == 1 &&
 780                                         r->reconf_type == 1)
 781                                 memcpy(reconf_key, r->key, sizeof(r->key));
 782                 } else if (otype != DHCPV6_OPT_CLIENTID &&
 783                                 otype != DHCPV6_OPT_SERVERID) {
 784                         odhcp6c_add_state(STATE_CUSTOM_OPTS,
 785                                         &odata[-4], olen + 4);
 786                 }
 787         }
 788
 789         return true;
 790 }
 791
 792
 793 static uint32_t dhcpv6_parse_ia(void *opt, void *end)
 794 {
 795         uint32_t timeout = UINT32_MAX; // Minimum timeout
 796         uint16_t otype, olen;
 797         uint8_t *odata;
 798
 799         struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT,
 800                         0, 0, IN6ADDR_ANY_INIT, 0, 0};
 801
 802         // Update address IA
 803         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 804                 if (otype == DHCPV6_OPT_IA_PREFIX) {
 805                         struct dhcpv6_ia_prefix *prefix = (void*)&odata[-4];
 806                         if (olen + 4U < sizeof(*prefix))
 807                                 continue;
 808
 809                         entry.valid = ntohl(prefix->valid);
 810                         entry.preferred = ntohl(prefix->preferred);
 811
 812                         if (entry.preferred > entry.valid)
 813                                 continue;
 814
 815                         entry.length = prefix->prefix;
 816                         entry.target = prefix->addr;
 817
 818                         // Parse PD-exclude
 819                         bool ok = true;
 820                         uint16_t stype, slen;
 821                         uint8_t *sdata;
 822                         dhcpv6_for_each_option(odata + sizeof(*prefix) - 4U,
 823                                         odata + olen, stype, slen, sdata) {
 824                                 if (stype != DHCPV6_OPT_PD_EXCLUDE || slen < 2)
 825                                         continue;
 826
 827                                 uint8_t elen = sdata[0];
 828                                 if (elen > 64)
 829                                         elen = 64;
 830
 831                                 if (elen <= 32 || elen <= entry.length) {
 832                                         ok = false;
 833                                         continue;
 834                                 }
 835
 836
 837                                 uint8_t bytes = ((elen - entry.length - 1) / 8) + 1;
 838                                 if (slen <= bytes) {
 839                                         ok = false;
 840                                         continue;
 841                                 }
 842
 843                                 uint32_t exclude = 0;
 844                                 do {
 845                                         exclude = exclude << 8 | sdata[bytes];
 846                                 } while (--bytes);
 847
 848                                 exclude >>= 8 - ((elen - entry.length) % 8);
 849                                 exclude <<= 64 - elen;
 850
 851                                 // Abusing router & priority fields for exclusion
 852                                 entry.router = entry.target;
 853                                 entry.router.s6_addr32[1] |= htonl(exclude);
 854                                 entry.priority = elen;
 855                         }
 856
 857                         if (ok)
 858                                 odhcp6c_update_entry(STATE_IA_PD, &entry);
 859
 860                         entry.priority = 0;
 861                         memset(&entry.router, 0, sizeof(entry.router));
 862                 } else if (otype == DHCPV6_OPT_IA_ADDR) {
 863                         struct dhcpv6_ia_addr *addr = (void*)&odata[-4];
 864                         if (olen + 4U < sizeof(*addr))
 865                                 continue;
 866
 867                         entry.preferred = ntohl(addr->preferred);
 868                         entry.valid = ntohl(addr->valid);
 869
 870                         if (entry.preferred > entry.valid)
 871                                 continue;
 872
 873                         entry.length = 128;
 874                         entry.target = addr->addr;
 875
 876                         odhcp6c_update_entry(STATE_IA_NA, &entry);
 877                 }
 878
 879                 if (entry.valid > 0 && timeout > entry.valid)
 880                         timeout = entry.valid;
 881         }
 882
 883         return timeout;
 884 }