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[] = {
 140                         htons(DHCPV6_OPT_SIP_SERVER_D),
 141                         htons(DHCPV6_OPT_SIP_SERVER_A),
 142                         htons(DHCPV6_OPT_DNS_SERVERS),
 143                         htons(DHCPV6_OPT_DNS_DOMAIN),
 144                         htons(DHCPV6_OPT_NTP_SERVER),
 145                         htons(DHCPV6_OPT_SIP_SERVER_A),
 146                         htons(DHCPV6_OPT_AFTR_NAME),
 147                         htons(DHCPV6_OPT_PD_EXCLUDE),
 148 #ifdef EXT_PREFIX_CLASS
 149                         htons(DHCPV6_OPT_PREFIX_CLASS),
 150 #endif
 151         };
 152         odhcp6c_add_state(STATE_ORO, oro, sizeof(oro));
 153
 154
 155         // Configure IPv6-options
 156         int val = 1;
 157         setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val));
 158         setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
 159         setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
 160
 161         struct sockaddr_in6 client_addr = { .sin6_family = AF_INET6,
 162                 .sin6_port = htons(DHCPV6_CLIENT_PORT), .sin6_flowinfo = 0 };
 163         if (bind(sock, (struct sockaddr*)&client_addr, sizeof(client_addr)))
 164                 return -1;
 165
 166         return 0;
 167 }
 168
 169
 170 void dhcpv6_set_ia_na_mode(enum odhcp6c_ia_mode mode)
 171 {
 172         na_mode = mode;
 173 }
 174
 175
 176 static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
 177 {
 178         // Build FQDN
 179         char fqdn_buf[256];
 180         gethostname(fqdn_buf, sizeof(fqdn_buf));
 181         struct {
 182                 uint16_t type;
 183                 uint16_t len;
 184                 uint8_t flags;
 185                 uint8_t data[256];
 186         } fqdn;
 187         size_t fqdn_len = 5 + dn_comp(fqdn_buf, fqdn.data,
 188                         sizeof(fqdn.data), NULL, NULL);
 189         fqdn.type = htons(DHCPV6_OPT_FQDN);
 190         fqdn.len = htons(fqdn_len - 4);
 191         fqdn.flags = 0;
 192
 193
 194         // Build Client ID
 195         size_t cl_id_len;
 196         void *cl_id = odhcp6c_get_state(STATE_CLIENT_ID, &cl_id_len);
 197
 198         // Get Server ID
 199         size_t srv_id_len;
 200         void *srv_id = odhcp6c_get_state(STATE_SERVER_ID, &srv_id_len);
 201
 202         // Build IA_PDs
 203         size_t ia_pd_entries, ia_pd_len = 0;
 204         struct odhcp6c_entry *e = odhcp6c_get_state(STATE_IA_PD, &ia_pd_entries);
 205         ia_pd_entries /= sizeof(*e);
 206         struct dhcpv6_ia_hdr hdr_ia_pd = {
 207                 htons(DHCPV6_OPT_IA_PD),
 208                 htons(sizeof(hdr_ia_pd) - 4),
 209                 1, 0, 0
 210         };
 211
 212
 213         uint8_t *ia_pd = alloca(ia_pd_entries * (sizeof(struct dhcpv6_ia_prefix) + 10));
 214         for (size_t i = 0; i < ia_pd_entries; ++i) {
 215                 uint8_t ex_len = 0;
 216                 if (e[i].priority > 0)
 217                         ex_len = ((e[i].priority - e[i].length - 1) / 8) + 6;
 218
 219                 struct dhcpv6_ia_prefix p = {
 220                         .type = htons(DHCPV6_OPT_IA_PREFIX),
 221                         .len = htons(sizeof(p) - 4U + ex_len),
 222                         .prefix = e[i].length,
 223                         .addr = e[i].target
 224                 };
 225
 226                 memcpy(ia_pd + ia_pd_len, &p, sizeof(p));
 227                 ia_pd_len += sizeof(p);
 228
 229                 if (ex_len) {
 230                         ia_pd[ia_pd_len++] = 0;
 231                         ia_pd[ia_pd_len++] = DHCPV6_OPT_PD_EXCLUDE;
 232                         ia_pd[ia_pd_len++] = 0;
 233                         ia_pd[ia_pd_len++] = ex_len - 4;
 234                         ia_pd[ia_pd_len++] = e[i].priority;
 235
 236                         uint32_t excl = ntohl(e[i].router.s6_addr32[1]);
 237                         excl >>= (64 - e[i].priority);
 238                         excl <<= 8 - ((e[i].priority - e[i].length) % 8);
 239
 240                         for (size_t i = ex_len - 5; i > 0; --i, excl >>= 8)
 241                                 ia_pd[ia_pd_len + i] = excl & 0xff;
 242                         ia_pd_len += ex_len - 5;
 243                 }
 244         }
 245
 246         struct dhcpv6_ia_prefix pref = {
 247                 .type = htons(DHCPV6_OPT_IA_PREFIX),
 248                 .len = htons(25), .prefix = request_prefix
 249         };
 250         if (request_prefix > 0 && ia_pd_len == 0 &&
 251                         (type == DHCPV6_MSG_SOLICIT ||
 252                         type == DHCPV6_MSG_REQUEST)) {
 253                 ia_pd = (uint8_t*)&pref;
 254                 ia_pd_len = sizeof(pref);
 255         }
 256         hdr_ia_pd.len = htons(ntohs(hdr_ia_pd.len) + ia_pd_len);
 257
 258         // Build IA_NAs
 259         size_t ia_na_entries, ia_na_len = 0;
 260         void *ia_na = NULL;
 261         e = odhcp6c_get_state(STATE_IA_NA, &ia_na_entries);
 262         ia_na_entries /= sizeof(*e);
 263
 264         struct dhcpv6_ia_hdr hdr_ia_na = {
 265                 htons(DHCPV6_OPT_IA_NA),
 266                 htons(sizeof(hdr_ia_na) - 4),
 267                 1, 0, 0
 268         };
 269
 270         struct dhcpv6_ia_addr pa[ia_na_entries];
 271         for (size_t i = 0; i < ia_na_entries; ++i) {
 272                 pa[i].type = htons(DHCPV6_OPT_IA_ADDR);
 273                 pa[i].len = htons(sizeof(pa[i]) - 4U);
 274                 pa[i].addr = e[i].target;
 275                 pa[i].preferred = 0;
 276                 pa[i].valid = 0;
 277         }
 278
 279         ia_na = pa;
 280         ia_na_len = sizeof(pa);
 281         hdr_ia_na.len = htons(ntohs(hdr_ia_na.len) + ia_na_len);
 282
 283         // Reconfigure Accept
 284         struct {
 285                 uint16_t type;
 286                 uint16_t length;
 287         } reconf_accept = {htons(DHCPV6_OPT_RECONF_ACCEPT), 0};
 288
 289         // Request Information Refresh
 290         uint16_t oro_refresh = htons(DHCPV6_OPT_INFO_REFRESH);
 291
 292         // Prepare Header
 293         size_t oro_len;
 294         void *oro = odhcp6c_get_state(STATE_ORO, &oro_len);
 295         struct {
 296                 uint8_t type;
 297                 uint8_t trid[3];
 298                 uint16_t elapsed_type;
 299                 uint16_t elapsed_len;
 300                 uint16_t elapsed_value;
 301                 uint16_t oro_type;
 302                 uint16_t oro_len;
 303         } hdr = {
 304                 type, {trid[0], trid[1], trid[2]},
 305                 htons(DHCPV6_OPT_ELAPSED), htons(2),
 306                         htons((ecs > 0xffff) ? 0xffff : ecs),
 307                 htons(DHCPV6_OPT_ORO), htons(oro_len),
 308         };
 309
 310         struct iovec iov[] = {
 311                 {&hdr, sizeof(hdr)},
 312                 {oro, oro_len},
 313                 {&oro_refresh, 0},
 314                 {cl_id, cl_id_len},
 315                 {srv_id, srv_id_len},
 316                 {&reconf_accept, sizeof(reconf_accept)},
 317                 {&fqdn, fqdn_len},
 318                 {&hdr_ia_na, sizeof(hdr_ia_na)},
 319                 {ia_na, ia_na_len},
 320                 {&hdr_ia_pd, sizeof(hdr_ia_pd)},
 321                 {ia_pd, ia_pd_len},
 322         };
 323
 324         size_t cnt = ARRAY_SIZE(iov);
 325         if (type == DHCPV6_MSG_INFO_REQ) {
 326                 cnt = 5;
 327                 iov[2].iov_len = sizeof(oro_refresh);
 328                 hdr.oro_len = htons(oro_len + sizeof(oro_refresh));
 329         } else if (!request_prefix) {
 330                 cnt = 9;
 331         }
 332
 333         // Disable IAs if not used
 334         if (type != DHCPV6_MSG_REQUEST && type != DHCPV6_MSG_SOLICIT) {
 335                 iov[5].iov_len = 0;
 336                 if (ia_na_len == 0)
 337                         iov[7].iov_len = 0;
 338                 if (ia_pd_len == 0)
 339                         iov[9].iov_len = 0;
 340         }
 341
 342         if (na_mode == IA_MODE_NONE)
 343                 iov[7].iov_len = 0;
 344
 345         struct sockaddr_in6 srv = {AF_INET6, htons(DHCPV6_SERVER_PORT),
 346                 0, ALL_DHCPV6_RELAYS, ifindex};
 347         struct msghdr msg = {&srv, sizeof(srv), iov, cnt, NULL, 0, 0};
 348
 349         sendmsg(sock, &msg, 0);
 350 }
 351
 352
 353 static int64_t dhcpv6_rand_delay(int64_t time)
 354 {
 355         int random;
 356         odhcp6c_random(&random, sizeof(random));
 357         return (time * ((int64_t)random % 1000LL)) / 10000LL;
 358 }
 359
 360
 361 int dhcpv6_request(enum dhcpv6_msg type)
 362 {
 363         uint8_t buf[1536];
 364         uint64_t timeout = UINT32_MAX;
 365         struct dhcpv6_retx *retx = &dhcpv6_retx[type];
 366
 367         if (retx->delay) {
 368                 struct timespec ts = {0, 0};
 369                 ts.tv_nsec = dhcpv6_rand_delay(10 * DHCPV6_REQ_DELAY);
 370                 nanosleep(&ts, NULL);
 371         }
 372
 373         if (type == DHCPV6_MSG_RELEASE || type == DHCPV6_MSG_DECLINE)
 374                 timeout = 3;
 375         else if (type == DHCPV6_MSG_UNKNOWN)
 376                 timeout = t1;
 377         else if (type == DHCPV6_MSG_RENEW)
 378                 timeout = (t2 > t1) ? t2 - t1 : 0;
 379         else if (type == DHCPV6_MSG_REBIND)
 380                 timeout = (t3 > t2) ? t3 - t2 : 0;
 381
 382         if (timeout == 0)
 383                 return -1;
 384
 385         syslog(LOG_NOTICE, "Sending %s (timeout %us)", retx->name, (unsigned)timeout);
 386
 387         uint64_t start = odhcp6c_get_milli_time(), round_start = start, elapsed;
 388
 389         // Generate transaction ID
 390         uint8_t trid[3] = {0, 0, 0};
 391         if (type != DHCPV6_MSG_UNKNOWN)
 392                 odhcp6c_random(trid, sizeof(trid));
 393         ssize_t len = -1;
 394         int64_t rto = 0;
 395
 396         do {
 397                 rto = (rto == 0) ? (retx->init_timeo * 1000 +
 398                                 dhcpv6_rand_delay(retx->init_timeo * 1000)) :
 399                                 (2 * rto + dhcpv6_rand_delay(rto));
 400
 401                 if (rto >= retx->max_timeo * 1000)
 402                         rto = retx->max_timeo * 1000 +
 403                                 dhcpv6_rand_delay(retx->max_timeo * 1000);
 404
 405                 // Calculate end for this round and elapsed time
 406                 uint64_t round_end = round_start + rto;
 407                 elapsed = round_start - start;
 408
 409                 // Don't wait too long
 410                 if (round_end - start > timeout * 1000)
 411                         round_end = timeout * 1000 + start;
 412
 413                 // Built and send package
 414                 if (type != DHCPV6_MSG_UNKNOWN)
 415                         dhcpv6_send(type, trid, elapsed / 10);
 416
 417                 // Receive rounds
 418                 for (; len < 0 && round_start < round_end;
 419                                 round_start = odhcp6c_get_milli_time()) {
 420                         // Check for pending signal
 421                         if (odhcp6c_signal_process())
 422                                 return -1;
 423
 424                         // Set timeout for receiving
 425                         uint64_t t = round_end - round_start;
 426                         struct timeval timeout = {t / 1000, (t % 1000) * 1000};
 427                         setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
 428                                         &timeout, sizeof(timeout));
 429
 430                         // Receive cycle
 431                         len = recv(sock, buf, sizeof(buf), 0);
 432
 433                         if (!dhcpv6_response_is_valid(buf, len, trid, type))
 434                                 len = -1;
 435
 436                         if (len > 0) {
 437                                 uint8_t *opt = &buf[4];
 438                                 uint8_t *opt_end = opt + len - 4;
 439
 440                                 round_start = odhcp6c_get_milli_time();
 441                                 elapsed = round_start - start;
 442                                 syslog(LOG_NOTICE, "Got a valid reply after "
 443                                                 "%ums", (unsigned)elapsed);
 444
 445                                 if (retx->handler_reply)
 446                                         len = retx->handler_reply(
 447                                                         type, opt, opt_end);
 448
 449                                 if (round_end - round_start > 1000)
 450                                         round_end = 1000 + round_start;
 451                         }
 452                 }
 453
 454                 // Allow
 455                 if (retx->handler_finish)
 456                         len = retx->handler_finish();
 457         } while (len < 0 && elapsed / 1000 < timeout);
 458
 459         return len;
 460 }
 461
 462
 463 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
 464                 const uint8_t transaction[3], enum dhcpv6_msg type)
 465 {
 466         const struct dhcpv6_header *rep = buf;
 467         if (len < (ssize_t)sizeof(*rep) || memcmp(rep->tr_id,
 468                         transaction, sizeof(rep->tr_id)))
 469                 return false; // Invalid reply
 470
 471         if (type == DHCPV6_MSG_SOLICIT) {
 472                 if (rep->msg_type != DHCPV6_MSG_ADVERT &&
 473                                 rep->msg_type != DHCPV6_MSG_REPLY)
 474                         return false;
 475         } else if (type == DHCPV6_MSG_UNKNOWN) {
 476                 if (!accept_reconfig || rep->msg_type != DHCPV6_MSG_RECONF)
 477                         return false;
 478         } else if (rep->msg_type != DHCPV6_MSG_REPLY) {
 479                 return false;
 480         }
 481
 482         uint8_t *end = ((uint8_t*)buf) + len, *odata;
 483         uint16_t otype, olen;
 484         bool clientid_ok = false, serverid_ok = false, rcauth_ok = false;
 485
 486         size_t client_id_len, server_id_len;
 487         void *client_id = odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 488         void *server_id = odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 489
 490         dhcpv6_for_each_option(&rep[1], end, otype, olen, odata) {
 491                 if (otype == DHCPV6_OPT_CLIENTID) {
 492                         clientid_ok = (olen + 4U == client_id_len) && !memcmp(
 493                                         &odata[-4], client_id, client_id_len);
 494                 } else if (otype == DHCPV6_OPT_SERVERID) {
 495                         serverid_ok = (olen + 4U == server_id_len) && !memcmp(
 496                                         &odata[-4], server_id, server_id_len);
 497                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 498                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 499                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 500                         if (r->protocol != 3 || r->algorithm != 1 || r->reconf_type != 2)
 501                                 continue;
 502
 503                         md5_state_t md5;
 504                         uint8_t serverhash[16], secretbytes[16], hash[16];
 505                         memcpy(serverhash, r->key, sizeof(serverhash));
 506                         memset(r->key, 0, sizeof(r->key));
 507                         memcpy(secretbytes, reconf_key, sizeof(secretbytes));
 508
 509                         for (size_t i = 0; i < sizeof(secretbytes); ++i)
 510                                 secretbytes[i] ^= 0x36;
 511
 512                         md5_init(&md5);
 513                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 514                         md5_append(&md5, buf, len);
 515                         md5_finish(&md5, hash);
 516
 517                         for (size_t i = 0; i < sizeof(secretbytes); ++i) {
 518                                 secretbytes[i] ^= 0x36;
 519                                 secretbytes[i] ^= 0x5c;
 520                         }
 521
 522                         md5_init(&md5);
 523                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 524                         md5_append(&md5, hash, 16);
 525                         md5_finish(&md5, hash);
 526
 527                         rcauth_ok = !memcmp(hash, serverhash, sizeof(hash));
 528                 }
 529         }
 530
 531         if (rep->msg_type == DHCPV6_MSG_RECONF && !rcauth_ok)
 532                 return false;
 533
 534         return clientid_ok && (serverid_ok || server_id_len == 0);
 535 }
 536
 537
 538 int dhcpv6_poll_reconfigure(void)
 539 {
 540         int ret = dhcpv6_request(DHCPV6_MSG_UNKNOWN);
 541         if (ret != -1)
 542                 ret = dhcpv6_request(ret);
 543
 544         return ret;
 545 }
 546
 547
 548 static int dhcpv6_handle_reconfigure(_unused enum dhcpv6_msg orig,
 549                 const void *opt, const void *end)
 550 {
 551         // TODO: should verify the reconfigure message
 552         uint16_t otype, olen;
 553         uint8_t *odata, msg = DHCPV6_MSG_RENEW;
 554         dhcpv6_for_each_option(opt, end, otype, olen, odata)
 555                 if (otype == DHCPV6_OPT_RECONF_MESSAGE && olen == 1 && (
 556                                 odata[0] == DHCPV6_MSG_RENEW ||
 557                                 odata[0] == DHCPV6_MSG_INFO_REQ))
 558                         msg = odata[0];
 559
 560         dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 561         return msg;
 562 }
 563
 564
 565 // Collect all advertised servers
 566 static int dhcpv6_handle_advert(enum dhcpv6_msg orig,
 567                 const void *opt, const void *end)
 568 {
 569         uint16_t olen, otype;
 570         uint8_t *odata;
 571         struct dhcpv6_server_cand cand = {false, false, 0, 0, {0}, NULL, NULL, 0, 0};
 572
 573         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 574                 if (orig == DHCPV6_MSG_SOLICIT &&
 575                                 (otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA) &&
 576                                 olen > sizeof(struct dhcpv6_ia_hdr)) {
 577                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 578                         dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 579                 }
 580
 581                 if (otype == DHCPV6_OPT_SERVERID && olen <= 130) {
 582                         memcpy(cand.duid, odata, olen);
 583                         cand.duid_len = olen;
 584                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 585                                 && odata[1] == DHCPV6_NoAddrsAvail) {
 586                         if (na_mode == IA_MODE_FORCE) {
 587                                 return -1;
 588                         } else {
 589                                 cand.has_noaddravail = true;
 590                                 cand.preference -= 1000;
 591                         }
 592                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 593                                 && odata[1] == DHCPV6_NoPrefixAvail) {
 594                         cand.preference -= 2000;
 595                 } else if (otype == DHCPV6_OPT_PREF && olen >= 1 &&
 596                                 cand.preference >= 0) {
 597                         cand.preference = odata[0];
 598                 } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
 599                         cand.wants_reconfigure = true;
 600                 } else if (otype == DHCPV6_OPT_IA_PD && request_prefix) {
 601                         struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
 602                         uint8_t *oend = odata + olen, *d;
 603                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d) {
 604                                 if (otype == DHCPV6_OPT_IA_PREFIX)
 605                                         cand.preference += 2000;
 606                                 else if (otype == DHCPV6_OPT_STATUS &&
 607                                                 olen >= 2 && d[0] == 0 &&
 608                                                 d[1] == DHCPV6_NoPrefixAvail)
 609                                         cand.preference -= 2000;
 610                         }
 611                 }
 612         }
 613
 614         if (cand.duid_len > 0) {
 615                 cand.ia_na = odhcp6c_move_state(STATE_IA_NA, &cand.ia_na_len);
 616                 cand.ia_pd = odhcp6c_move_state(STATE_IA_PD, &cand.ia_pd_len);
 617                 odhcp6c_add_state(STATE_SERVER_CAND, &cand, sizeof(cand));
 618         }
 619
 620         if (orig == DHCPV6_MSG_SOLICIT) {
 621                 odhcp6c_clear_state(STATE_IA_NA);
 622                 odhcp6c_clear_state(STATE_IA_PD);
 623         }
 624
 625         return -1;
 626 }
 627
 628
 629 static int dhcpv6_commit_advert(void)
 630 {
 631         size_t cand_len;
 632         struct dhcpv6_server_cand *c = NULL, *cand =
 633                         odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
 634
 635         bool retry = false;
 636         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 637                 if (cand[i].has_noaddravail)
 638                         retry = true; // We want to try again
 639
 640                 if (!c || c->preference < cand[i].preference)
 641                         c = &cand[i];
 642         }
 643
 644         if (retry && na_mode == IA_MODE_TRY) {
 645                 // We give it a second try without the IA_NA
 646                 na_mode = IA_MODE_NONE;
 647                 return dhcpv6_request(DHCPV6_MSG_SOLICIT);
 648         }
 649
 650         if (c) {
 651                 uint16_t hdr[2] = {htons(DHCPV6_OPT_SERVERID),
 652                                 htons(c->duid_len)};
 653                 odhcp6c_add_state(STATE_SERVER_ID, hdr, sizeof(hdr));
 654                 odhcp6c_add_state(STATE_SERVER_ID, c->duid, c->duid_len);
 655                 accept_reconfig = c->wants_reconfigure;
 656                 odhcp6c_add_state(STATE_IA_NA, c->ia_na, c->ia_na_len);
 657                 odhcp6c_add_state(STATE_IA_PD, c->ia_pd, c->ia_pd_len);
 658         }
 659
 660         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 661                 free(cand[i].ia_na);
 662                 free(cand[i].ia_pd);
 663         }
 664         odhcp6c_clear_state(STATE_SERVER_CAND);
 665
 666         if (!c)
 667                 return -1;
 668         else if (request_prefix || na_mode != IA_MODE_NONE)
 669                 return DHCPV6_STATEFUL;
 670         else
 671                 return DHCPV6_STATELESS;
 672 }
 673
 674
 675 static int dhcpv6_handle_rebind_reply(enum dhcpv6_msg orig,
 676                 const void *opt, const void *end)
 677 {
 678         dhcpv6_handle_advert(orig, opt, end);
 679         if (dhcpv6_commit_advert() < 0) {
 680                 dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 681                 return -1;
 682         }
 683
 684         return dhcpv6_handle_reply(orig, opt, end);
 685 }
 686
 687
 688 static int dhcpv6_handle_reply(enum dhcpv6_msg orig,
 689                 const void *opt, const void *end)
 690 {
 691         uint8_t *odata;
 692         uint16_t otype, olen;
 693
 694         odhcp6c_expire();
 695
 696         if (orig == DHCPV6_MSG_UNKNOWN) {
 697                 static time_t last_update = 0;
 698                 time_t now = odhcp6c_get_milli_time() / 1000;
 699
 700                 uint32_t elapsed = (last_update > 0) ? now - last_update : 0;
 701                 last_update = now;
 702
 703                 t1 -= elapsed;
 704                 t2 -= elapsed;
 705                 t3 -= elapsed;
 706
 707                 if (t1 < 0)
 708                         t1 = 0;
 709
 710                 if (t2 < 0)
 711                         t2 = 0;
 712
 713                 if (t3 < 0)
 714                         t3 = 0;
 715         } else {
 716                 t1 = t2 = t3 = UINT32_MAX;
 717         }
 718
 719         if (orig == DHCPV6_MSG_REQUEST) {
 720                 // Delete NA and PD we have in the state from the Advert
 721                 odhcp6c_clear_state(STATE_IA_NA);
 722                 odhcp6c_clear_state(STATE_IA_PD);
 723         }
 724
 725         if (opt) {
 726                 odhcp6c_clear_state(STATE_DNS);
 727                 odhcp6c_clear_state(STATE_SEARCH);
 728                 odhcp6c_clear_state(STATE_SNTP_IP);
 729                 odhcp6c_clear_state(STATE_SNTP_FQDN);
 730                 odhcp6c_clear_state(STATE_SIP_IP);
 731                 odhcp6c_clear_state(STATE_SIP_FQDN);
 732                 odhcp6c_clear_state(STATE_AFTR_NAME);
 733         }
 734
 735         // Parse and find all matching IAs
 736         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 737                 if ((otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA)
 738                                 && olen > sizeof(struct dhcpv6_ia_hdr)) {
 739                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 740                         uint32_t l_t1 = ntohl(ia_hdr->t1);
 741                         uint32_t l_t2 = ntohl(ia_hdr->t2);
 742
 743                         // Test ID and T1-T2 validity
 744                         if (ia_hdr->iaid != 1 || l_t2 < l_t1)
 745                                 continue;
 746
 747                         int error = 0;
 748                         uint16_t stype, slen;
 749                         uint8_t *sdata;
 750                         // Test status and bail if error
 751                         dhcpv6_for_each_option(&ia_hdr[1], odata + olen,
 752                                         stype, slen, sdata)
 753                                 if (stype == DHCPV6_OPT_STATUS && slen >= 2)
 754                                         error = ((int)sdata[0]) << 8 | ((int)sdata[1]);
 755
 756                         if (error) {
 757                                 syslog(LOG_WARNING, "Server returned IAID status %i!", error);
 758                                 raise(SIGUSR2);
 759                                 break;
 760                         }
 761
 762                         uint32_t n = dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 763
 764                         if (!l_t1)
 765                                 l_t1 = 300;
 766
 767                         if (!l_t2)
 768                                 l_t2 = 600;
 769
 770                         if (n < t3)
 771                                 t3 = n;
 772
 773                         // Update times
 774                         if (l_t1 > 0 && t1 > l_t1)
 775                                 t1 = l_t1;
 776
 777                         if (l_t2 > 0 && t2 > l_t2)
 778                                 t2 = l_t2;
 779
 780                 } else if (otype == DHCPV6_OPT_DNS_SERVERS) {
 781                         if (olen % 16 == 0)
 782                                 odhcp6c_add_state(STATE_DNS, odata, olen);
 783                 } else if (otype == DHCPV6_OPT_DNS_DOMAIN) {
 784                         odhcp6c_add_state(STATE_SEARCH, odata, olen);
 785                 } else if (otype == DHCPV6_OPT_NTP_SERVER) {
 786                         uint16_t stype, slen;
 787                         uint8_t *sdata;
 788                         // Test status and bail if error
 789                         dhcpv6_for_each_option(odata, odata + olen,
 790                                         stype, slen, sdata) {
 791                                 if (slen == 16 && (stype == NTP_MC_ADDR ||
 792                                                 stype == NTP_SRV_ADDR))
 793                                         odhcp6c_add_state(STATE_SNTP_IP,
 794                                                         sdata, slen);
 795                                 else if (slen > 0 && stype == NTP_SRV_FQDN)
 796                                         odhcp6c_add_state(STATE_SNTP_FQDN,
 797                                                         sdata, slen);
 798                         }
 799                 } else if (otype == DHCPV6_OPT_SIP_SERVER_A) {
 800                         if (olen == 16)
 801                                 odhcp6c_add_state(STATE_SIP_IP, odata, olen);
 802                 } else if (otype == DHCPV6_OPT_SIP_SERVER_D) {
 803                         odhcp6c_add_state(STATE_SIP_FQDN, odata, olen);
 804                 } else if (otype == DHCPV6_OPT_INFO_REFRESH && olen >= 4) {
 805                         uint32_t refresh = ntohl(*((uint32_t*)odata));
 806                         if (refresh < (uint32_t)t1)
 807                                 t1 = refresh;
 808                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 809                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 810                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 811                         if (r->protocol == 3 && r->algorithm == 1 &&
 812                                         r->reconf_type == 1)
 813                                 memcpy(reconf_key, r->key, sizeof(r->key));
 814                 } else if (otype == DHCPV6_OPT_AFTR_NAME && olen > 3) {
 815                         size_t cur_len;
 816                         odhcp6c_get_state(STATE_AFTR_NAME, &cur_len);
 817                         if (cur_len == 0)
 818                                 odhcp6c_add_state(STATE_AFTR_NAME, odata, olen);
 819                 } else if (otype != DHCPV6_OPT_CLIENTID &&
 820                                 otype != DHCPV6_OPT_SERVERID) {
 821                         odhcp6c_add_state(STATE_CUSTOM_OPTS,
 822                                         &odata[-4], olen + 4);
 823                 }
 824         }
 825
 826         if (t1 == UINT32_MAX)
 827                 t1 = 300;
 828
 829         if (t2 == UINT32_MAX)
 830                 t2 = 600;
 831
 832         if (t3 == UINT32_MAX)
 833                 t3 = 3600;
 834
 835         return true;
 836 }
 837
 838
 839 static uint32_t dhcpv6_parse_ia(void *opt, void *end)
 840 {
 841         uint32_t timeout = UINT32_MAX; // Minimum timeout
 842         uint16_t otype, olen;
 843         uint8_t *odata;
 844
 845         // Update address IA
 846         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 847                 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, 0, 0,
 848                                 IN6ADDR_ANY_INIT, 0, 0, 0};
 849
 850                 if (otype == DHCPV6_OPT_IA_PREFIX) {
 851                         struct dhcpv6_ia_prefix *prefix = (void*)&odata[-4];
 852                         if (olen + 4U < sizeof(*prefix))
 853                                 continue;
 854
 855                         entry.valid = ntohl(prefix->valid);
 856                         entry.preferred = ntohl(prefix->preferred);
 857
 858                         if (entry.preferred > entry.valid)
 859                                 continue;
 860
 861                         entry.length = prefix->prefix;
 862                         entry.target = prefix->addr;
 863                         uint16_t stype, slen;
 864                         uint8_t *sdata;
 865
 866 #ifdef EXT_PREFIX_CLASS
 867                         // Find prefix class, if any
 868                         dhcpv6_for_each_option(&prefix[1], odata + olen,
 869                                         stype, slen, sdata)
 870                                 if (stype == DHCPV6_OPT_PREFIX_CLASS && slen == 2)
 871                                         entry.class = sdata[0] << 8 | sdata[1];
 872 #endif
 873
 874                         // Parse PD-exclude
 875                         bool ok = true;
 876                         dhcpv6_for_each_option(odata + sizeof(*prefix) - 4U,
 877                                         odata + olen, stype, slen, sdata) {
 878                                 if (stype != DHCPV6_OPT_PD_EXCLUDE || slen < 2)
 879                                         continue;
 880
 881                                 uint8_t elen = sdata[0];
 882                                 if (elen > 64)
 883                                         elen = 64;
 884
 885                                 if (elen <= 32 || elen <= entry.length) {
 886                                         ok = false;
 887                                         continue;
 888                                 }
 889
 890
 891                                 uint8_t bytes = ((elen - entry.length - 1) / 8) + 1;
 892                                 if (slen <= bytes) {
 893                                         ok = false;
 894                                         continue;
 895                                 }
 896
 897                                 uint32_t exclude = 0;
 898                                 do {
 899                                         exclude = exclude << 8 | sdata[bytes];
 900                                 } while (--bytes);
 901
 902                                 exclude >>= 8 - ((elen - entry.length) % 8);
 903                                 exclude <<= 64 - elen;
 904
 905                                 // Abusing router & priority fields for exclusion
 906                                 entry.router = entry.target;
 907                                 entry.router.s6_addr32[1] |= htonl(exclude);
 908                                 entry.priority = elen;
 909                         }
 910
 911                         if (ok)
 912                                 odhcp6c_update_entry(STATE_IA_PD, &entry);
 913
 914                         entry.priority = 0;
 915                         memset(&entry.router, 0, sizeof(entry.router));
 916                 } else if (otype == DHCPV6_OPT_IA_ADDR) {
 917                         struct dhcpv6_ia_addr *addr = (void*)&odata[-4];
 918                         if (olen + 4U < sizeof(*addr))
 919                                 continue;
 920
 921                         entry.preferred = ntohl(addr->preferred);
 922                         entry.valid = ntohl(addr->valid);
 923
 924                         if (entry.preferred > entry.valid)
 925                                 continue;
 926
 927                         entry.length = 128;
 928                         entry.target = addr->addr;
 929
 930 #ifdef EXT_PREFIX_CLASS
 931                         uint16_t stype, slen;
 932                         uint8_t *sdata;
 933                         // Find prefix class, if any
 934                         dhcpv6_for_each_option(&addr[1], odata + olen,
 935                                         stype, slen, sdata)
 936                                 if (stype == DHCPV6_OPT_PREFIX_CLASS && slen == 2)
 937                                         entry.class = sdata[0] << 8 | sdata[1];
 938 #endif
 939
 940                         odhcp6c_update_entry(STATE_IA_NA, &entry);
 941                 }
 942                 if (entry.valid > 0 && timeout > entry.valid)
 943                         timeout = entry.valid;
 944         }
 945
 946         return timeout;
 947 }