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, 120, "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];
 385         odhcp6c_random(trid, sizeof(trid));
 386         ssize_t len = -1;
 387         int64_t rto = 0;
 388
 389         do {
 390                 rto = (rto == 0) ? (retx->init_timeo * 1000 +
 391                                 dhcpv6_rand_delay(retx->init_timeo * 1000)) :
 392                                 (2 * rto + dhcpv6_rand_delay(rto));
 393
 394                 if (rto >= retx->max_timeo * 1000)
 395                         rto = retx->max_timeo * 1000 +
 396                                 dhcpv6_rand_delay(retx->max_timeo * 1000);
 397
 398                 // Calculate end for this round and elapsed time
 399                 uint64_t round_end = round_start + rto;
 400                 elapsed = round_start - start;
 401
 402                 // Don't wait too long
 403                 if (round_end - start > timeout * 1000)
 404                         round_end = timeout * 1000 + start;
 405
 406                 // Built and send package
 407                 if (type != DHCPV6_MSG_UNKNOWN)
 408                         dhcpv6_send(type, trid, elapsed / 10);
 409
 410                 // Receive rounds
 411                 for (; len < 0 && round_start < round_end;
 412                                 round_start = odhcp6c_get_milli_time()) {
 413                         // Check for pending signal
 414                         if (odhcp6c_signal_process())
 415                                 return -1;
 416
 417                         // Set timeout for receiving
 418                         uint64_t t = round_end - round_start;
 419                         struct timeval timeout = {t / 1000, (t % 1000) * 1000};
 420                         setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
 421                                         &timeout, sizeof(timeout));
 422
 423                         // Receive cycle
 424                         len = recv(sock, buf, sizeof(buf), 0);
 425
 426                         if (!dhcpv6_response_is_valid(buf, len, trid, type))
 427                                 len = -1;
 428
 429                         if (len > 0) {
 430                                 uint8_t *opt = &buf[4];
 431                                 uint8_t *opt_end = opt + len - 4;
 432
 433                                 round_start = odhcp6c_get_milli_time();
 434                                 elapsed = round_start - start;
 435                                 syslog(LOG_NOTICE, "Got a valid reply after "
 436                                                 "%ums", (unsigned)elapsed);
 437
 438                                 if (retx->handler_reply)
 439                                         len = retx->handler_reply(
 440                                                         type, opt, opt_end);
 441
 442                                 if (round_end - round_start > 1000)
 443                                         round_end = 1000 + round_start;
 444                         }
 445                 }
 446
 447                 // Allow
 448                 if (retx->handler_finish)
 449                         len = retx->handler_finish();
 450         } while (len < 0 && elapsed / 1000 < timeout);
 451
 452         return len;
 453 }
 454
 455
 456 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
 457                 const uint8_t transaction[3], enum dhcpv6_msg type)
 458 {
 459         const struct dhcpv6_header *rep = buf;
 460         if (len < (ssize_t)sizeof(*rep) || memcmp(rep->tr_id,
 461                         transaction, sizeof(rep->tr_id)))
 462                 return false; // Invalid reply
 463
 464         if (type == DHCPV6_MSG_SOLICIT) {
 465                 if (rep->msg_type != DHCPV6_MSG_ADVERT &&
 466                                 rep->msg_type != DHCPV6_MSG_REPLY)
 467                         return false;
 468         } else if (type == DHCPV6_MSG_UNKNOWN) {
 469                 if (!accept_reconfig || rep->msg_type != DHCPV6_MSG_RECONF)
 470                         return false;
 471         } else if (rep->msg_type != DHCPV6_MSG_REPLY) {
 472                 return false;
 473         }
 474
 475         uint8_t *end = ((uint8_t*)buf) + len, *odata;
 476         uint16_t otype, olen;
 477         bool clientid_ok = false, serverid_ok = false, rcauth_ok = false;
 478
 479         size_t client_id_len, server_id_len;
 480         void *client_id = odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 481         void *server_id = odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 482
 483         dhcpv6_for_each_option(&rep[1], end, otype, olen, odata) {
 484                 if (otype == DHCPV6_OPT_CLIENTID) {
 485                         clientid_ok = (olen + 4U == client_id_len) && !memcmp(
 486                                         &odata[-4], client_id, client_id_len);
 487                 } else if (otype == DHCPV6_OPT_SERVERID) {
 488                         serverid_ok = (olen + 4U == server_id_len) && !memcmp(
 489                                         &odata[-4], server_id, server_id_len);
 490                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 491                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 492                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 493                         if (r->protocol != 3 || r->algorithm != 1 || r->reconf_type != 2)
 494                                 continue;
 495
 496                         md5_state_t md5;
 497                         uint8_t serverhash[16], secretbytes[16], hash[16];
 498                         memcpy(serverhash, r->key, sizeof(serverhash));
 499                         memset(r->key, 0, sizeof(r->key));
 500                         memcpy(secretbytes, reconf_key, sizeof(secretbytes));
 501
 502                         for (size_t i = 0; i < sizeof(secretbytes); ++i)
 503                                 secretbytes[i] ^= 0x36;
 504
 505                         md5_init(&md5);
 506                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 507                         md5_append(&md5, buf, len);
 508                         md5_finish(&md5, hash);
 509
 510                         for (size_t i = 0; i < sizeof(secretbytes); ++i) {
 511                                 secretbytes[i] ^= 0x36;
 512                                 secretbytes[i] ^= 0x5c;
 513                         }
 514
 515                         md5_init(&md5);
 516                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 517                         md5_append(&md5, hash, 16);
 518                         md5_finish(&md5, hash);
 519
 520                         rcauth_ok = !memcmp(hash, serverhash, sizeof(hash));
 521                 }
 522         }
 523
 524         if (rep->msg_type == DHCPV6_MSG_RECONF && !rcauth_ok)
 525                 return false;
 526
 527         return clientid_ok && (serverid_ok || server_id_len == 0);
 528 }
 529
 530
 531 int dhcpv6_poll_reconfigure(void)
 532 {
 533         int ret = dhcpv6_request(DHCPV6_MSG_UNKNOWN);
 534         if (ret != -1)
 535                 ret = dhcpv6_request(ret);
 536
 537         return ret;
 538 }
 539
 540
 541 static int dhcpv6_handle_reconfigure(_unused enum dhcpv6_msg orig,
 542                 const void *opt, const void *end)
 543 {
 544         // TODO: should verify the reconfigure message
 545         uint16_t otype, olen;
 546         uint8_t *odata, msg = DHCPV6_MSG_RENEW;
 547         dhcpv6_for_each_option(opt, end, otype, olen, odata)
 548                 if (otype == DHCPV6_OPT_RECONF_MESSAGE && olen == 1 && (
 549                                 odata[0] == DHCPV6_MSG_RENEW ||
 550                                 odata[0] == DHCPV6_MSG_INFO_REQ))
 551                         msg = odata[0];
 552
 553         dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 554         return msg;
 555 }
 556
 557
 558 // Collect all advertised servers
 559 static int dhcpv6_handle_advert(_unused enum dhcpv6_msg orig,
 560                 const void *opt, const void *end)
 561 {
 562         uint16_t olen, otype;
 563         uint8_t *odata;
 564         struct dhcpv6_server_cand cand = {false, false, 0, 0, {0}};
 565
 566         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 567                 if (otype == DHCPV6_OPT_SERVERID && olen <= 130) {
 568                         memcpy(cand.duid, odata, olen);
 569                         cand.duid_len = olen;
 570                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 571                                 && odata[1] == DHCPV6_NoAddrsAvail) {
 572                         if (na_mode == IA_MODE_FORCE) {
 573                                 return -1;
 574                         } else {
 575                                 cand.has_noaddravail = true;
 576                                 cand.preference -= 1000;
 577                         }
 578                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 579                                 && odata[1] == DHCPV6_NoPrefixAvail) {
 580                         cand.preference -= 2000;
 581                 } else if (otype == DHCPV6_OPT_PREF && olen >= 1 &&
 582                                 cand.preference >= 0) {
 583                         cand.preference = odata[0];
 584                 } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
 585                         cand.wants_reconfigure = true;
 586                 } else if (otype == DHCPV6_OPT_IA_PD && request_prefix) {
 587                         struct dhcpv6_ia_hdr *h = (void*)odata;
 588                         uint8_t *oend = odata + olen, *d;
 589                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d) {
 590                                 if (otype == DHCPV6_OPT_IA_PREFIX)
 591                                         cand.preference += 2000;
 592                                 else if (otype == DHCPV6_OPT_STATUS &&
 593                                                 olen >= 2 && d[0] == 0 &&
 594                                                 d[1] == DHCPV6_NoPrefixAvail)
 595                                         cand.preference -= 2000;
 596                         }
 597                 }
 598         }
 599
 600         if (cand.duid_len > 0)
 601                 odhcp6c_add_state(STATE_SERVER_CAND, &cand, sizeof(cand));
 602
 603         return -1;
 604 }
 605
 606
 607 static int dhcpv6_commit_advert(void)
 608 {
 609         size_t cand_len;
 610         struct dhcpv6_server_cand *c = NULL, *cand =
 611                         odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
 612
 613         bool retry = false;
 614         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 615                 if (cand[i].has_noaddravail)
 616                         retry = true; // We want to try again
 617
 618                 if (!c || c->preference < cand[i].preference)
 619                         c = &cand[i];
 620         }
 621
 622         if (retry && na_mode == IA_MODE_TRY) {
 623                 // We give it a second try without the IA_NA
 624                 na_mode = IA_MODE_NONE;
 625                 return dhcpv6_request(DHCPV6_MSG_SOLICIT);
 626         }
 627
 628         if (c) {
 629                 uint16_t hdr[2] = {htons(DHCPV6_OPT_SERVERID),
 630                                 htons(c->duid_len)};
 631                 odhcp6c_add_state(STATE_SERVER_ID, hdr, sizeof(hdr));
 632                 odhcp6c_add_state(STATE_SERVER_ID, c->duid, c->duid_len);
 633                 accept_reconfig = c->wants_reconfigure;
 634         }
 635
 636         odhcp6c_clear_state(STATE_SERVER_CAND);
 637
 638         if (!c)
 639                 return -1;
 640         else if (request_prefix || na_mode != IA_MODE_NONE)
 641                 return DHCPV6_STATEFUL;
 642         else
 643                 return DHCPV6_STATELESS;
 644 }
 645
 646
 647 static int dhcpv6_handle_rebind_reply(enum dhcpv6_msg orig,
 648                 const void *opt, const void *end)
 649 {
 650         dhcpv6_handle_advert(orig, opt, end);
 651         if (dhcpv6_commit_advert() < 0) {
 652                 dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 653                 return -1;
 654         }
 655
 656         return dhcpv6_handle_reply(orig, opt, end);
 657 }
 658
 659
 660 static int dhcpv6_handle_reply(enum dhcpv6_msg orig,
 661                 const void *opt, const void *end)
 662 {
 663         uint8_t *odata;
 664         uint16_t otype, olen;
 665
 666         static time_t last_update = 0;
 667         time_t now = odhcp6c_get_milli_time() / 1000;
 668
 669         uint32_t elapsed = now - last_update;
 670         odhcp6c_expire();
 671
 672         if (orig == DHCPV6_MSG_UNKNOWN) {
 673                 t1 -= elapsed;
 674                 t2 -= elapsed;
 675                 t3 -= elapsed;
 676
 677                 if (t1 < 0)
 678                         t1 = 0;
 679
 680                 if (t2 < 0)
 681                         t2 = 0;
 682
 683                 if (t3 < 0)
 684                         t3 = 0;
 685         } else {
 686                 t1 = t2 = t3 = UINT32_MAX;
 687         }
 688
 689         if (opt) {
 690                 odhcp6c_clear_state(STATE_DNS);
 691                 odhcp6c_clear_state(STATE_SEARCH);
 692                 odhcp6c_clear_state(STATE_SNTP_IP);
 693                 odhcp6c_clear_state(STATE_SNTP_FQDN);
 694                 odhcp6c_clear_state(STATE_SIP_IP);
 695                 odhcp6c_clear_state(STATE_SIP_FQDN);
 696         }
 697
 698         // Parse and find all matching IAs
 699         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 700                 if ((otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA)
 701                                 && olen > sizeof(struct dhcpv6_ia_hdr)) {
 702                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 703                         uint32_t l_t1 = ntohl(ia_hdr->t1);
 704                         uint32_t l_t2 = ntohl(ia_hdr->t2);
 705
 706                         // Test ID and T1-T2 validity
 707                         if (ia_hdr->iaid != 1 || l_t2 < l_t1)
 708                                 continue;
 709
 710                         bool error = false;
 711                         uint16_t stype, slen;
 712                         uint8_t *sdata;
 713                         // Test status and bail if error
 714                         dhcpv6_for_each_option(&ia_hdr[1], odata + olen,
 715                                         stype, slen, sdata)
 716                                 if (stype == DHCPV6_OPT_STATUS && slen >= 2 &&
 717                                                 (sdata[0] || sdata[1]))
 718                                         error = true;
 719
 720                         if (error)
 721                                 continue;
 722
 723                         // Update times
 724                         if (l_t1 > 0 && t1 > l_t1)
 725                                 t1 = l_t1;
 726
 727                         if (l_t2 > 0 && t2 > l_t2)
 728                                 t2 = l_t2;
 729
 730                         uint32_t n = dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 731
 732                         if (n < t1)
 733                                 t1 = n;
 734
 735                         if (n < t2)
 736                                 t2 = n;
 737
 738                         if (n < t3)
 739                                 t3 = n;
 740
 741                         if (t2 >= t3)
 742                                 t2 = 8 * t3 / 10;
 743
 744                         if (t1 >= t2)
 745                                 t1 = 5 * t2 / 8;
 746
 747                 } else if (otype == DHCPV6_OPT_DNS_SERVERS) {
 748                         if (olen % 16 == 0)
 749                                 odhcp6c_add_state(STATE_DNS, odata, olen);
 750                 } else if (otype == DHCPV6_OPT_DNS_DOMAIN) {
 751                         odhcp6c_add_state(STATE_SEARCH, odata, olen);
 752                 } else if (otype == DHCPV6_OPT_NTP_SERVER) {
 753                         uint16_t stype, slen;
 754                         uint8_t *sdata;
 755                         // Test status and bail if error
 756                         dhcpv6_for_each_option(odata, odata + olen,
 757                                         stype, slen, sdata) {
 758                                 if (slen == 16 && (stype == NTP_MC_ADDR ||
 759                                                 stype == NTP_SRV_ADDR))
 760                                         odhcp6c_add_state(STATE_SNTP_IP,
 761                                                         sdata, slen);
 762                                 else if (slen > 0 && stype == NTP_SRV_FQDN)
 763                                         odhcp6c_add_state(STATE_SNTP_FQDN,
 764                                                         sdata, slen);
 765                         }
 766                 } else if (otype == DHCPV6_OPT_SIP_SERVER_A) {
 767                         if (olen == 16)
 768                                 odhcp6c_add_state(STATE_SIP_IP, odata, olen);
 769                 } else if (otype == DHCPV6_OPT_SIP_SERVER_D) {
 770                         odhcp6c_add_state(STATE_SIP_FQDN, odata, olen);
 771                 } else if (otype == DHCPV6_OPT_INFO_REFRESH && olen >= 4) {
 772                         uint32_t refresh = ntohl(*((uint32_t*)odata));
 773                         if (refresh < (uint32_t)t1)
 774                                 t1 = refresh;
 775                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 776                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 777                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 778                         if (r->protocol == 3 && r->algorithm == 1 &&
 779                                         r->reconf_type == 1)
 780                                 memcpy(reconf_key, r->key, sizeof(r->key));
 781                 } else if (otype != DHCPV6_OPT_CLIENTID &&
 782                                 otype != DHCPV6_OPT_SERVERID) {
 783                         odhcp6c_add_state(STATE_CUSTOM_OPTS,
 784                                         &odata[-4], olen + 4);
 785                 }
 786         }
 787
 788         return true;
 789 }
 790
 791
 792 static uint32_t dhcpv6_parse_ia(void *opt, void *end)
 793 {
 794         uint32_t timeout = UINT32_MAX; // Minimum timeout
 795         uint16_t otype, olen;
 796         uint8_t *odata;
 797
 798         struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT,
 799                         0, 0, IN6ADDR_ANY_INIT, 0, 0};
 800
 801         // Update address IA
 802         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 803                 if (otype == DHCPV6_OPT_IA_PREFIX) {
 804                         struct dhcpv6_ia_prefix *prefix = (void*)&odata[-4];
 805                         if (olen + 4U < sizeof(*prefix))
 806                                 continue;
 807
 808                         entry.valid = ntohl(prefix->valid);
 809                         entry.preferred = ntohl(prefix->preferred);
 810
 811                         if (entry.preferred > entry.valid)
 812                                 continue;
 813
 814                         entry.length = prefix->prefix;
 815                         entry.target = prefix->addr;
 816
 817                         // Parse PD-exclude
 818                         bool ok = true;
 819                         uint16_t stype, slen;
 820                         uint8_t *sdata;
 821                         dhcpv6_for_each_option(odata + sizeof(*prefix) - 4U,
 822                                         odata + olen, stype, slen, sdata) {
 823                                 if (stype != DHCPV6_OPT_PD_EXCLUDE || slen < 2)
 824                                         continue;
 825
 826                                 uint8_t elen = sdata[0];
 827                                 if (elen > 64)
 828                                         elen = 64;
 829
 830                                 if (elen <= 32 || elen <= entry.length) {
 831                                         ok = false;
 832                                         continue;
 833                                 }
 834
 835
 836                                 uint8_t bytes = ((elen - entry.length - 1) / 8) + 1;
 837                                 if (slen <= bytes) {
 838                                         ok = false;
 839                                         continue;
 840                                 }
 841
 842                                 uint32_t exclude = 0;
 843                                 do {
 844                                         exclude = exclude << 8 | sdata[bytes];
 845                                 } while (--bytes);
 846
 847                                 exclude >>= 8 - ((elen - entry.length) % 8);
 848                                 exclude <<= 64 - elen;
 849
 850                                 // Abusing router & priority fields for exclusion
 851                                 entry.router = entry.target;
 852                                 entry.router.s6_addr32[1] |= htonl(exclude);
 853                                 entry.priority = elen;
 854                         }
 855
 856                         if (ok)
 857                                 odhcp6c_update_entry(STATE_IA_PD, &entry);
 858
 859                         entry.priority = 0;
 860                         memset(&entry.router, 0, sizeof(entry.router));
 861                 } else if (otype == DHCPV6_OPT_IA_ADDR) {
 862                         struct dhcpv6_ia_addr *addr = (void*)&odata[-4];
 863                         if (olen + 4U < sizeof(*addr))
 864                                 continue;
 865
 866                         entry.preferred = ntohl(addr->preferred);
 867                         entry.valid = ntohl(addr->valid);
 868
 869                         if (entry.preferred > entry.valid)
 870                                 continue;
 871
 872                         entry.length = 128;
 873                         entry.target = addr->addr;
 874
 875                         odhcp6c_update_entry(STATE_IA_NA, &entry);
 876                 }
 877
 878                 if (entry.valid > 0 && timeout > entry.valid)
 879                         timeout = entry.valid;
 880         }
 881
 882         return timeout;
 883 }