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, 0, "<POLL>",
  62                         dhcpv6_handle_reconfigure, NULL},
  63         [DHCPV6_MSG_SOLICIT] = {true, 1, 3600, 0, "SOLICIT",
  64                         dhcpv6_handle_advert, dhcpv6_commit_advert},
  65         [DHCPV6_MSG_REQUEST] = {true, 1, 30, 10, "REQUEST",
  66                         dhcpv6_handle_reply, NULL},
  67         [DHCPV6_MSG_RENEW] = {false, 10, 600, 0, "RENEW",
  68                         dhcpv6_handle_reply, NULL},
  69         [DHCPV6_MSG_REBIND] = {false, 10, 600, 0, "REBIND",
  70                         dhcpv6_handle_rebind_reply, NULL},
  71         [DHCPV6_MSG_RELEASE] = {false, 1, 0, 5, "RELEASE", NULL, NULL},
  72         [DHCPV6_MSG_DECLINE] = {false, 1, 0, 5, "DECLINE", NULL, NULL},
  73         [DHCPV6_MSG_INFO_REQ] = {true, 1, 120, 0, "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, pd_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, int sol_timeout)
  94 {
  95         request_prefix = request_pd;
  96         dhcpv6_retx[DHCPV6_MSG_SOLICIT].max_timeo = sol_timeout;
  97
  98         sock = socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
  99
 100         // Detect interface
 101         struct ifreq ifr;
 102         strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
 103         if (ioctl(sock, SIOCGIFINDEX, &ifr))
 104                 return -1;
 105         ifindex = ifr.ifr_ifindex;
 106
 107         // Create client DUID
 108         size_t client_id_len;
 109         odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 110         if (client_id_len == 0) {
 111                 ioctl(sock, SIOCGIFHWADDR, &ifr);
 112                 uint8_t duid[14] = {0, DHCPV6_OPT_CLIENTID, 0, 10, 0,
 113                                 DHCPV6_DUID_LLADDR, 0, 1};
 114                 memcpy(&duid[8], ifr.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
 115
 116                 uint8_t zero[ETHER_ADDR_LEN] = {0, 0, 0, 0, 0, 0};
 117                 struct ifreq ifs[100], *ifp, *ifend;
 118                 struct ifconf ifc;
 119                 ifc.ifc_req = ifs;
 120                 ifc.ifc_len = sizeof(ifs);
 121
 122                 if (!memcmp(&duid[8], zero, ETHER_ADDR_LEN) &&
 123                                 ioctl(sock, SIOCGIFCONF, &ifc) >= 0) {
 124                         // If our interface doesn't have an address...
 125                         ifend = ifs + (ifc.ifc_len / sizeof(struct ifreq));
 126                         for (ifp = ifc.ifc_req; ifp < ifend &&
 127                                         !memcmp(&duid[8], zero, 6); ifp++) {
 128                                 memcpy(ifr.ifr_name, ifp->ifr_name,
 129                                                 sizeof(ifr.ifr_name));
 130                                 ioctl(sock, SIOCGIFHWADDR, &ifr);
 131                                 memcpy(&duid[8], ifr.ifr_hwaddr.sa_data,
 132                                                 ETHER_ADDR_LEN);
 133                         }
 134                 }
 135
 136                 odhcp6c_add_state(STATE_CLIENT_ID, duid, sizeof(duid));
 137         }
 138
 139         // Create ORO
 140         uint16_t oro[] = {
 141                         htons(DHCPV6_OPT_SIP_SERVER_D),
 142                         htons(DHCPV6_OPT_SIP_SERVER_A),
 143                         htons(DHCPV6_OPT_DNS_SERVERS),
 144                         htons(DHCPV6_OPT_DNS_DOMAIN),
 145                         htons(DHCPV6_OPT_NTP_SERVER),
 146                         htons(DHCPV6_OPT_SIP_SERVER_A),
 147                         htons(DHCPV6_OPT_AFTR_NAME),
 148                         htons(DHCPV6_OPT_PD_EXCLUDE),
 149 #ifdef EXT_PREFIX_CLASS
 150                         htons(DHCPV6_OPT_PREFIX_CLASS),
 151 #endif
 152         };
 153         odhcp6c_add_state(STATE_ORO, oro, sizeof(oro));
 154
 155
 156         // Configure IPv6-options
 157         int val = 1;
 158         setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val));
 159         setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
 160         val = 0;
 161         setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &val, sizeof(val));
 162         setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
 163
 164         struct sockaddr_in6 client_addr = { .sin6_family = AF_INET6,
 165                 .sin6_port = htons(DHCPV6_CLIENT_PORT), .sin6_flowinfo = 0 };
 166         if (bind(sock, (struct sockaddr*)&client_addr, sizeof(client_addr)))
 167                 return -1;
 168
 169         return 0;
 170 }
 171
 172
 173 void dhcpv6_set_ia_mode(enum odhcp6c_ia_mode na, enum odhcp6c_ia_mode pd)
 174 {
 175         na_mode = na;
 176         pd_mode = pd;
 177 }
 178
 179
 180 static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
 181 {
 182         // Build FQDN
 183         char fqdn_buf[256];
 184         gethostname(fqdn_buf, sizeof(fqdn_buf));
 185         struct {
 186                 uint16_t type;
 187                 uint16_t len;
 188                 uint8_t flags;
 189                 uint8_t data[256];
 190         } fqdn;
 191         size_t fqdn_len = 5 + dn_comp(fqdn_buf, fqdn.data,
 192                         sizeof(fqdn.data), NULL, NULL);
 193         fqdn.type = htons(DHCPV6_OPT_FQDN);
 194         fqdn.len = htons(fqdn_len - 4);
 195         fqdn.flags = 0;
 196
 197
 198         // Build Client ID
 199         size_t cl_id_len;
 200         void *cl_id = odhcp6c_get_state(STATE_CLIENT_ID, &cl_id_len);
 201
 202         // Get Server ID
 203         size_t srv_id_len;
 204         void *srv_id = odhcp6c_get_state(STATE_SERVER_ID, &srv_id_len);
 205
 206         // Build IA_PDs
 207         size_t ia_pd_entries, ia_pd_len = 0;
 208         struct odhcp6c_entry *e = odhcp6c_get_state(STATE_IA_PD, &ia_pd_entries);
 209         ia_pd_entries /= sizeof(*e);
 210         struct dhcpv6_ia_hdr hdr_ia_pd = {
 211                 htons(DHCPV6_OPT_IA_PD),
 212                 htons(sizeof(hdr_ia_pd) - 4),
 213                 1, 0, 0
 214         };
 215
 216
 217         uint8_t *ia_pd = alloca(ia_pd_entries * (sizeof(struct dhcpv6_ia_prefix) + 10));
 218         for (size_t i = 0; i < ia_pd_entries; ++i) {
 219                 uint8_t ex_len = 0;
 220                 if (e[i].priority > 0)
 221                         ex_len = ((e[i].priority - e[i].length - 1) / 8) + 6;
 222
 223                 struct dhcpv6_ia_prefix p = {
 224                         .type = htons(DHCPV6_OPT_IA_PREFIX),
 225                         .len = htons(sizeof(p) - 4U + ex_len),
 226                         .prefix = e[i].length,
 227                         .addr = e[i].target
 228                 };
 229
 230                 memcpy(ia_pd + ia_pd_len, &p, sizeof(p));
 231                 ia_pd_len += sizeof(p);
 232
 233                 if (ex_len) {
 234                         ia_pd[ia_pd_len++] = 0;
 235                         ia_pd[ia_pd_len++] = DHCPV6_OPT_PD_EXCLUDE;
 236                         ia_pd[ia_pd_len++] = 0;
 237                         ia_pd[ia_pd_len++] = ex_len - 4;
 238                         ia_pd[ia_pd_len++] = e[i].priority;
 239
 240                         uint32_t excl = ntohl(e[i].router.s6_addr32[1]);
 241                         excl >>= (64 - e[i].priority);
 242                         excl <<= 8 - ((e[i].priority - e[i].length) % 8);
 243
 244                         for (size_t i = ex_len - 5; i > 0; --i, excl >>= 8)
 245                                 ia_pd[ia_pd_len + i] = excl & 0xff;
 246                         ia_pd_len += ex_len - 5;
 247                 }
 248         }
 249
 250         struct dhcpv6_ia_prefix pref = {
 251                 .type = htons(DHCPV6_OPT_IA_PREFIX),
 252                 .len = htons(25), .prefix = request_prefix
 253         };
 254         if (request_prefix > 0 && ia_pd_len == 0 && type == DHCPV6_MSG_SOLICIT) {
 255                 ia_pd = (uint8_t*)&pref;
 256                 ia_pd_len = sizeof(pref);
 257         }
 258         hdr_ia_pd.len = htons(ntohs(hdr_ia_pd.len) + ia_pd_len);
 259
 260         // Build IA_NAs
 261         size_t ia_na_entries, ia_na_len = 0;
 262         void *ia_na = NULL;
 263         e = odhcp6c_get_state(STATE_IA_NA, &ia_na_entries);
 264         ia_na_entries /= sizeof(*e);
 265
 266         struct dhcpv6_ia_hdr hdr_ia_na = {
 267                 htons(DHCPV6_OPT_IA_NA),
 268                 htons(sizeof(hdr_ia_na) - 4),
 269                 1, 0, 0
 270         };
 271
 272         struct dhcpv6_ia_addr pa[ia_na_entries];
 273         for (size_t i = 0; i < ia_na_entries; ++i) {
 274                 pa[i].type = htons(DHCPV6_OPT_IA_ADDR);
 275                 pa[i].len = htons(sizeof(pa[i]) - 4U);
 276                 pa[i].addr = e[i].target;
 277                 pa[i].preferred = 0;
 278                 pa[i].valid = 0;
 279         }
 280
 281         ia_na = pa;
 282         ia_na_len = sizeof(pa);
 283         hdr_ia_na.len = htons(ntohs(hdr_ia_na.len) + ia_na_len);
 284
 285         // Reconfigure Accept
 286         struct {
 287                 uint16_t type;
 288                 uint16_t length;
 289         } reconf_accept = {htons(DHCPV6_OPT_RECONF_ACCEPT), 0};
 290
 291         // Request Information Refresh
 292         uint16_t oro_refresh = htons(DHCPV6_OPT_INFO_REFRESH);
 293
 294         // Prepare Header
 295         size_t oro_len;
 296         void *oro = odhcp6c_get_state(STATE_ORO, &oro_len);
 297         struct {
 298                 uint8_t type;
 299                 uint8_t trid[3];
 300                 uint16_t elapsed_type;
 301                 uint16_t elapsed_len;
 302                 uint16_t elapsed_value;
 303                 uint16_t oro_type;
 304                 uint16_t oro_len;
 305         } hdr = {
 306                 type, {trid[0], trid[1], trid[2]},
 307                 htons(DHCPV6_OPT_ELAPSED), htons(2),
 308                         htons((ecs > 0xffff) ? 0xffff : ecs),
 309                 htons(DHCPV6_OPT_ORO), htons(oro_len),
 310         };
 311
 312         struct iovec iov[] = {
 313                 {&hdr, sizeof(hdr)},
 314                 {oro, oro_len},
 315                 {&oro_refresh, 0},
 316                 {cl_id, cl_id_len},
 317                 {srv_id, srv_id_len},
 318                 {&reconf_accept, sizeof(reconf_accept)},
 319                 {&fqdn, fqdn_len},
 320                 {&hdr_ia_na, sizeof(hdr_ia_na)},
 321                 {ia_na, ia_na_len},
 322                 {&hdr_ia_pd, sizeof(hdr_ia_pd)},
 323                 {ia_pd, ia_pd_len},
 324         };
 325
 326         size_t cnt = ARRAY_SIZE(iov);
 327         if (type == DHCPV6_MSG_INFO_REQ) {
 328                 cnt = 5;
 329                 iov[2].iov_len = sizeof(oro_refresh);
 330                 hdr.oro_len = htons(oro_len + sizeof(oro_refresh));
 331         } else if (!request_prefix) {
 332                 cnt = 9;
 333         }
 334
 335         // Disable IAs if not used
 336         if (type != DHCPV6_MSG_SOLICIT) {
 337                 iov[5].iov_len = 0;
 338                 if (ia_na_len == 0)
 339                         iov[7].iov_len = 0;
 340                 if (ia_pd_len == 0)
 341                         iov[9].iov_len = 0;
 342         }
 343
 344         if (na_mode == IA_MODE_NONE)
 345                 iov[7].iov_len = 0;
 346
 347         struct sockaddr_in6 srv = {AF_INET6, htons(DHCPV6_SERVER_PORT),
 348                 0, ALL_DHCPV6_RELAYS, ifindex};
 349         struct msghdr msg = {&srv, sizeof(srv), iov, cnt, NULL, 0, 0};
 350
 351         sendmsg(sock, &msg, 0);
 352 }
 353
 354
 355 static int64_t dhcpv6_rand_delay(int64_t time)
 356 {
 357         int random;
 358         odhcp6c_random(&random, sizeof(random));
 359         return (time * ((int64_t)random % 1000LL)) / 10000LL;
 360 }
 361
 362
 363 int dhcpv6_request(enum dhcpv6_msg type)
 364 {
 365         uint8_t buf[1536], rc = 0;
 366         uint64_t timeout = UINT32_MAX;
 367         struct dhcpv6_retx *retx = &dhcpv6_retx[type];
 368
 369         if (retx->delay) {
 370                 struct timespec ts = {0, 0};
 371                 ts.tv_nsec = dhcpv6_rand_delay(10 * DHCPV6_REQ_DELAY);
 372                 nanosleep(&ts, NULL);
 373         }
 374
 375         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, "Starting %s transaction (timeout %llus, max rc %d)", retx->name, timeout, retx->max_rc);
 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                 if (rto == 0) {
 398                         int64_t delay = dhcpv6_rand_delay(retx->init_timeo * 1000);
 399
 400                         // First RT MUST be strictly greater than IRT for solicit messages (RFC3313 17.1.2)
 401                         while (type == DHCPV6_MSG_SOLICIT && delay <= 0)
 402                                 delay = dhcpv6_rand_delay(retx->init_timeo * 1000);
 403
 404                         rto = (retx->init_timeo * 1000 + delay);
 405                 }
 406                 else
 407                         rto = (2 * rto + dhcpv6_rand_delay(rto));
 408
 409                 if (retx->max_timeo && (rto >= retx->max_timeo * 1000))
 410                         rto = retx->max_timeo * 1000 +
 411                                 dhcpv6_rand_delay(retx->max_timeo * 1000);
 412
 413                 // Calculate end for this round and elapsed time
 414                 uint64_t round_end = round_start + rto;
 415                 elapsed = round_start - start;
 416
 417                 // Don't wait too long
 418                 if (round_end - start > timeout * 1000)
 419                         round_end = timeout * 1000 + start;
 420
 421                 // Built and send package
 422                 if (type != DHCPV6_MSG_UNKNOWN) {
 423                         syslog(LOG_NOTICE, "Send %s message (elapsed %llums, rc %d)", retx->name, elapsed, rc);
 424                         dhcpv6_send(type, trid, elapsed / 10);
 425                         rc++;
 426                 }
 427
 428                 // Receive rounds
 429                 for (; len < 0 && round_start < round_end;
 430                                 round_start = odhcp6c_get_milli_time()) {
 431                         // Check for pending signal
 432                         if (odhcp6c_signal_process())
 433                                 return -1;
 434
 435                         // Set timeout for receiving
 436                         uint64_t t = round_end - round_start;
 437                         struct timeval timeout = {t / 1000, (t % 1000) * 1000};
 438                         setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
 439                                         &timeout, sizeof(timeout));
 440
 441                         // Receive cycle
 442                         len = recv(sock, buf, sizeof(buf), 0);
 443
 444                         if (!dhcpv6_response_is_valid(buf, len, trid, type))
 445                                 len = -1;
 446
 447                         if (len > 0) {
 448                                 uint8_t *opt = &buf[4];
 449                                 uint8_t *opt_end = opt + len - 4;
 450
 451                                 round_start = odhcp6c_get_milli_time();
 452                                 elapsed = round_start - start;
 453                                 syslog(LOG_NOTICE, "Got a valid reply after "
 454                                                 "%llums", elapsed);
 455
 456                                 if (retx->handler_reply)
 457                                         len = retx->handler_reply(
 458                                                         type, rc, opt, opt_end);
 459
 460                                 if (len > 0 && round_end - round_start > 1000)
 461                                         round_end = 1000 + round_start;
 462                         }
 463                 }
 464
 465                 // Allow
 466                 if (retx->handler_finish)
 467                         len = retx->handler_finish();
 468         } while (len < 0 && ((elapsed / 1000 < timeout) && (!retx->max_rc || rc < retx->max_rc)));
 469
 470         return len;
 471 }
 472
 473
 474 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
 475                 const uint8_t transaction[3], enum dhcpv6_msg type)
 476 {
 477         const struct dhcpv6_header *rep = buf;
 478         if (len < (ssize_t)sizeof(*rep) || memcmp(rep->tr_id,
 479                         transaction, sizeof(rep->tr_id)))
 480                 return false; // Invalid reply
 481
 482         if (type == DHCPV6_MSG_SOLICIT) {
 483                 if (rep->msg_type != DHCPV6_MSG_ADVERT &&
 484                                 rep->msg_type != DHCPV6_MSG_REPLY)
 485                         return false;
 486         } else if (type == DHCPV6_MSG_UNKNOWN) {
 487                 if (!accept_reconfig || rep->msg_type != DHCPV6_MSG_RECONF)
 488                         return false;
 489         } else if (rep->msg_type != DHCPV6_MSG_REPLY) {
 490                 return false;
 491         }
 492
 493         uint8_t *end = ((uint8_t*)buf) + len, *odata;
 494         uint16_t otype, olen;
 495         bool clientid_ok = false, serverid_ok = false, rcauth_ok = false;
 496
 497         size_t client_id_len, server_id_len;
 498         void *client_id = odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 499         void *server_id = odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 500
 501         dhcpv6_for_each_option(&rep[1], end, otype, olen, odata) {
 502                 if (otype == DHCPV6_OPT_CLIENTID) {
 503                         clientid_ok = (olen + 4U == client_id_len) && !memcmp(
 504                                         &odata[-4], client_id, client_id_len);
 505                 } else if (otype == DHCPV6_OPT_SERVERID) {
 506                         serverid_ok = (olen + 4U == server_id_len) && !memcmp(
 507                                         &odata[-4], server_id, server_id_len);
 508                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 509                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 510                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 511                         if (r->protocol != 3 || r->algorithm != 1 || r->reconf_type != 2)
 512                                 continue;
 513
 514                         md5_state_t md5;
 515                         uint8_t serverhash[16], secretbytes[16], hash[16];
 516                         memcpy(serverhash, r->key, sizeof(serverhash));
 517                         memset(r->key, 0, sizeof(r->key));
 518                         memcpy(secretbytes, reconf_key, sizeof(secretbytes));
 519
 520                         for (size_t i = 0; i < sizeof(secretbytes); ++i)
 521                                 secretbytes[i] ^= 0x36;
 522
 523                         md5_init(&md5);
 524                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 525                         md5_append(&md5, buf, len);
 526                         md5_finish(&md5, hash);
 527
 528                         for (size_t i = 0; i < sizeof(secretbytes); ++i) {
 529                                 secretbytes[i] ^= 0x36;
 530                                 secretbytes[i] ^= 0x5c;
 531                         }
 532
 533                         md5_init(&md5);
 534                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 535                         md5_append(&md5, hash, 16);
 536                         md5_finish(&md5, hash);
 537
 538                         rcauth_ok = !memcmp(hash, serverhash, sizeof(hash));
 539                 }
 540         }
 541
 542         if (rep->msg_type == DHCPV6_MSG_RECONF && !rcauth_ok)
 543                 return false;
 544
 545         return clientid_ok && (serverid_ok || server_id_len == 0);
 546 }
 547
 548
 549 int dhcpv6_poll_reconfigure(void)
 550 {
 551         int ret = dhcpv6_request(DHCPV6_MSG_UNKNOWN);
 552         if (ret != -1)
 553                 ret = dhcpv6_request(ret);
 554
 555         return ret;
 556 }
 557
 558
 559 static int dhcpv6_handle_reconfigure(_unused enum dhcpv6_msg orig, const int rc,
 560                 const void *opt, const void *end)
 561 {
 562         // TODO: should verify the reconfigure message
 563         uint16_t otype, olen;
 564         uint8_t *odata, msg = DHCPV6_MSG_RENEW;
 565         dhcpv6_for_each_option(opt, end, otype, olen, odata)
 566                 if (otype == DHCPV6_OPT_RECONF_MESSAGE && olen == 1 && (
 567                                 odata[0] == DHCPV6_MSG_RENEW ||
 568                                 odata[0] == DHCPV6_MSG_INFO_REQ))
 569                         msg = odata[0];
 570
 571         dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, rc, NULL, NULL);
 572         return msg;
 573 }
 574
 575
 576 // Collect all advertised servers
 577 static int dhcpv6_handle_advert(enum dhcpv6_msg orig, _unused const int rc,
 578                 const void *opt, const void *end)
 579 {
 580         uint16_t olen, otype;
 581         uint8_t *odata;
 582         struct dhcpv6_server_cand cand = {false, false, 0, 0, {0}, NULL, NULL, 0, 0};
 583         bool have_na = false;
 584         int have_pd = 0;
 585
 586         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 587                 if (orig == DHCPV6_MSG_SOLICIT &&
 588                                 (otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA) &&
 589                                 olen > sizeof(struct dhcpv6_ia_hdr)) {
 590                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 591                         dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 592                 }
 593
 594                 if (otype == DHCPV6_OPT_SERVERID && olen <= 130) {
 595                         memcpy(cand.duid, odata, olen);
 596                         cand.duid_len = olen;
 597                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 598                                 && odata[1] == DHCPV6_NoPrefixAvail) {
 599                         cand.preference -= 2000;
 600                 } else if (otype == DHCPV6_OPT_PREF && olen >= 1 &&
 601                                 cand.preference >= 0) {
 602                         cand.preference = odata[0];
 603                 } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
 604                         cand.wants_reconfigure = true;
 605                 } else if (otype == DHCPV6_OPT_IA_PD && request_prefix) {
 606                         struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
 607                         uint8_t *oend = odata + olen, *d;
 608                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d) {
 609                                 if (otype == DHCPV6_OPT_IA_PREFIX && (olen + 4) >=
 610                                                 (uint16_t)sizeof(struct dhcpv6_ia_prefix)) {
 611                                         struct dhcpv6_ia_prefix *p = (struct dhcpv6_ia_prefix*)&d[-4];
 612                                         have_pd = p->prefix;
 613                                 }
 614                         }
 615                 } else if (otype == DHCPV6_OPT_IA_NA) {
 616                         struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
 617                         uint8_t *oend = odata + olen, *d;
 618                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d)
 619                                 if (otype == DHCPV6_OPT_IA_ADDR)
 620                                         have_na = true;
 621                 }
 622         }
 623
 624         if ((!have_na && na_mode == IA_MODE_FORCE) ||
 625                         (!have_pd && pd_mode == IA_MODE_FORCE))
 626                 return -1;
 627
 628         if (na_mode != IA_MODE_NONE && !have_na) {
 629                 cand.has_noaddravail = true;
 630                 cand.preference -= 1000;
 631         }
 632
 633         if (pd_mode != IA_MODE_NONE) {
 634                 if (have_pd)
 635                         cand.preference += 2000 + (128 - have_pd);
 636                 else
 637                         cand.preference -= 2000;
 638         }
 639
 640         if (cand.duid_len > 0) {
 641                 cand.ia_na = odhcp6c_move_state(STATE_IA_NA, &cand.ia_na_len);
 642                 cand.ia_pd = odhcp6c_move_state(STATE_IA_PD, &cand.ia_pd_len);
 643                 odhcp6c_add_state(STATE_SERVER_CAND, &cand, sizeof(cand));
 644         }
 645
 646         if (orig == DHCPV6_MSG_SOLICIT) {
 647                 odhcp6c_clear_state(STATE_IA_NA);
 648                 odhcp6c_clear_state(STATE_IA_PD);
 649         }
 650
 651         return -1;
 652 }
 653
 654
 655 static int dhcpv6_commit_advert(void)
 656 {
 657         size_t cand_len;
 658         struct dhcpv6_server_cand *c = NULL, *cand =
 659                         odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
 660
 661         bool retry = false;
 662         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 663                 if (cand[i].has_noaddravail)
 664                         retry = true; // We want to try again
 665
 666                 if (!c || c->preference < cand[i].preference)
 667                         c = &cand[i];
 668         }
 669
 670         if (retry && na_mode == IA_MODE_TRY) {
 671                 // We give it a second try without the IA_NA
 672                 na_mode = IA_MODE_NONE;
 673                 return dhcpv6_request(DHCPV6_MSG_SOLICIT);
 674         }
 675
 676         if (c) {
 677                 uint16_t hdr[2] = {htons(DHCPV6_OPT_SERVERID),
 678                                 htons(c->duid_len)};
 679                 odhcp6c_add_state(STATE_SERVER_ID, hdr, sizeof(hdr));
 680                 odhcp6c_add_state(STATE_SERVER_ID, c->duid, c->duid_len);
 681                 accept_reconfig = c->wants_reconfigure;
 682                 odhcp6c_add_state(STATE_IA_NA, c->ia_na, c->ia_na_len);
 683                 odhcp6c_add_state(STATE_IA_PD, c->ia_pd, c->ia_pd_len);
 684         }
 685
 686         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 687                 free(cand[i].ia_na);
 688                 free(cand[i].ia_pd);
 689         }
 690         odhcp6c_clear_state(STATE_SERVER_CAND);
 691
 692         if (!c)
 693                 return -1;
 694         else if (request_prefix || na_mode != IA_MODE_NONE)
 695                 return DHCPV6_STATEFUL;
 696         else
 697                 return DHCPV6_STATELESS;
 698 }
 699
 700
 701 static int dhcpv6_handle_rebind_reply(enum dhcpv6_msg orig, const int rc,
 702                 const void *opt, const void *end)
 703 {
 704         dhcpv6_handle_advert(orig, rc, opt, end);
 705         if (dhcpv6_commit_advert() < 0) {
 706                 dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, rc, NULL, NULL);
 707                 return -1;
 708         }
 709
 710         return dhcpv6_handle_reply(orig, rc, opt, end);
 711 }
 712
 713
 714 static int dhcpv6_handle_reply(enum dhcpv6_msg orig, _unused const int rc,
 715                 const void *opt, const void *end)
 716 {
 717         uint8_t *odata;
 718         uint16_t otype, olen;
 719
 720         odhcp6c_expire();
 721
 722         if (orig == DHCPV6_MSG_UNKNOWN) {
 723                 static time_t last_update = 0;
 724                 time_t now = odhcp6c_get_milli_time() / 1000;
 725
 726                 uint32_t elapsed = (last_update > 0) ? now - last_update : 0;
 727                 last_update = now;
 728
 729                 t1 -= elapsed;
 730                 t2 -= elapsed;
 731                 t3 -= elapsed;
 732
 733                 if (t1 < 0)
 734                         t1 = 0;
 735
 736                 if (t2 < 0)
 737                         t2 = 0;
 738
 739                 if (t3 < 0)
 740                         t3 = 0;
 741         } else {
 742                 t1 = t2 = t3 = UINT32_MAX;
 743         }
 744
 745         if (orig == DHCPV6_MSG_REQUEST) {
 746                 // Delete NA and PD we have in the state from the Advert
 747                 odhcp6c_clear_state(STATE_IA_NA);
 748                 odhcp6c_clear_state(STATE_IA_PD);
 749         }
 750
 751         if (opt) {
 752                 odhcp6c_clear_state(STATE_DNS);
 753                 odhcp6c_clear_state(STATE_SEARCH);
 754                 odhcp6c_clear_state(STATE_SNTP_IP);
 755                 odhcp6c_clear_state(STATE_SNTP_FQDN);
 756                 odhcp6c_clear_state(STATE_SIP_IP);
 757                 odhcp6c_clear_state(STATE_SIP_FQDN);
 758                 odhcp6c_clear_state(STATE_AFTR_NAME);
 759         }
 760
 761         // Parse and find all matching IAs
 762         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 763                 if ((otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA)
 764                                 && olen > sizeof(struct dhcpv6_ia_hdr)) {
 765                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 766                         uint32_t l_t1 = ntohl(ia_hdr->t1);
 767                         uint32_t l_t2 = ntohl(ia_hdr->t2);
 768
 769                         // Test ID and T1-T2 validity
 770                         if (ia_hdr->iaid != 1 || l_t2 < l_t1)
 771                                 continue;
 772
 773                         int error = 0;
 774                         uint16_t stype, slen;
 775                         uint8_t *sdata;
 776                         // Test status and bail if error
 777                         dhcpv6_for_each_option(&ia_hdr[1], odata + olen,
 778                                         stype, slen, sdata)
 779                                 if (stype == DHCPV6_OPT_STATUS && slen >= 2)
 780                                         error = ((int)sdata[0]) << 8 | ((int)sdata[1]);
 781
 782                         if (error) {
 783                                 syslog(LOG_WARNING, "Server returned IAID status %i!", error);
 784                                 if (error != 2)
 785                                         raise(SIGUSR2);
 786                                 break;
 787                         }
 788
 789                         uint32_t n = dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 790
 791                         if (!l_t1)
 792                                 l_t1 = 300;
 793
 794                         if (!l_t2)
 795                                 l_t2 = 600;
 796
 797                         if (n < t3)
 798                                 t3 = n;
 799
 800                         // Update times
 801                         if (l_t1 > 0 && t1 > l_t1)
 802                                 t1 = l_t1;
 803
 804                         if (l_t2 > 0 && t2 > l_t2)
 805                                 t2 = l_t2;
 806
 807                 } else if (otype == DHCPV6_OPT_DNS_SERVERS) {
 808                         if (olen % 16 == 0)
 809                                 odhcp6c_add_state(STATE_DNS, odata, olen);
 810                 } else if (otype == DHCPV6_OPT_DNS_DOMAIN) {
 811                         odhcp6c_add_state(STATE_SEARCH, odata, olen);
 812                 } else if (otype == DHCPV6_OPT_NTP_SERVER) {
 813                         uint16_t stype, slen;
 814                         uint8_t *sdata;
 815                         // Test status and bail if error
 816                         dhcpv6_for_each_option(odata, odata + olen,
 817                                         stype, slen, sdata) {
 818                                 if (slen == 16 && (stype == NTP_MC_ADDR ||
 819                                                 stype == NTP_SRV_ADDR))
 820                                         odhcp6c_add_state(STATE_SNTP_IP,
 821                                                         sdata, slen);
 822                                 else if (slen > 0 && stype == NTP_SRV_FQDN)
 823                                         odhcp6c_add_state(STATE_SNTP_FQDN,
 824                                                         sdata, slen);
 825                         }
 826                 } else if (otype == DHCPV6_OPT_SIP_SERVER_A) {
 827                         if (olen == 16)
 828                                 odhcp6c_add_state(STATE_SIP_IP, odata, olen);
 829                 } else if (otype == DHCPV6_OPT_SIP_SERVER_D) {
 830                         odhcp6c_add_state(STATE_SIP_FQDN, odata, olen);
 831                 } else if (otype == DHCPV6_OPT_INFO_REFRESH && olen >= 4) {
 832                         uint32_t refresh = ntohl(*((uint32_t*)odata));
 833                         if (refresh < (uint32_t)t1)
 834                                 t1 = refresh;
 835                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 836                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 837                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 838                         if (r->protocol == 3 && r->algorithm == 1 &&
 839                                         r->reconf_type == 1)
 840                                 memcpy(reconf_key, r->key, sizeof(r->key));
 841                 } else if (otype == DHCPV6_OPT_AFTR_NAME && olen > 3) {
 842                         size_t cur_len;
 843                         odhcp6c_get_state(STATE_AFTR_NAME, &cur_len);
 844                         if (cur_len == 0)
 845                                 odhcp6c_add_state(STATE_AFTR_NAME, odata, olen);
 846                 } else if (otype != DHCPV6_OPT_CLIENTID &&
 847                                 otype != DHCPV6_OPT_SERVERID) {
 848                         odhcp6c_add_state(STATE_CUSTOM_OPTS,
 849                                         &odata[-4], olen + 4);
 850                 }
 851         }
 852
 853         if (t1 == UINT32_MAX)
 854                 t1 = 300;
 855
 856         if (t2 == UINT32_MAX)
 857                 t2 = 600;
 858
 859         if (t3 == UINT32_MAX)
 860                 t3 = 3600;
 861
 862         return true;
 863 }
 864
 865
 866 static uint32_t dhcpv6_parse_ia(void *opt, void *end)
 867 {
 868         uint32_t timeout = UINT32_MAX; // Minimum timeout
 869         uint16_t otype, olen;
 870         uint8_t *odata;
 871
 872         // Update address IA
 873         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 874                 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, 0, 0,
 875                                 IN6ADDR_ANY_INIT, 0, 0, 0};
 876
 877                 if (otype == DHCPV6_OPT_IA_PREFIX) {
 878                         struct dhcpv6_ia_prefix *prefix = (void*)&odata[-4];
 879                         if (olen + 4U < sizeof(*prefix))
 880                                 continue;
 881
 882                         entry.valid = ntohl(prefix->valid);
 883                         entry.preferred = ntohl(prefix->preferred);
 884
 885                         if (entry.preferred > entry.valid)
 886                                 continue;
 887
 888                         entry.length = prefix->prefix;
 889                         entry.target = prefix->addr;
 890                         uint16_t stype, slen;
 891                         uint8_t *sdata;
 892
 893 #ifdef EXT_PREFIX_CLASS
 894                         // Find prefix class, if any
 895                         dhcpv6_for_each_option(&prefix[1], odata + olen,
 896                                         stype, slen, sdata)
 897                                 if (stype == DHCPV6_OPT_PREFIX_CLASS && slen == 2)
 898                                         entry.class = sdata[0] << 8 | sdata[1];
 899 #endif
 900
 901                         // Parse PD-exclude
 902                         bool ok = true;
 903                         dhcpv6_for_each_option(odata + sizeof(*prefix) - 4U,
 904                                         odata + olen, stype, slen, sdata) {
 905                                 if (stype != DHCPV6_OPT_PD_EXCLUDE || slen < 2)
 906                                         continue;
 907
 908                                 uint8_t elen = sdata[0];
 909                                 if (elen > 64)
 910                                         elen = 64;
 911
 912                                 if (elen <= 32 || elen <= entry.length) {
 913                                         ok = false;
 914                                         continue;
 915                                 }
 916
 917
 918                                 uint8_t bytes = ((elen - entry.length - 1) / 8) + 1;
 919                                 if (slen <= bytes) {
 920                                         ok = false;
 921                                         continue;
 922                                 }
 923
 924                                 uint32_t exclude = 0;
 925                                 do {
 926                                         exclude = exclude << 8 | sdata[bytes];
 927                                 } while (--bytes);
 928
 929                                 exclude >>= 8 - ((elen - entry.length) % 8);
 930                                 exclude <<= 64 - elen;
 931
 932                                 // Abusing router & priority fields for exclusion
 933                                 entry.router = entry.target;
 934                                 entry.router.s6_addr32[1] |= htonl(exclude);
 935                                 entry.priority = elen;
 936                         }
 937
 938                         if (ok)
 939                                 odhcp6c_update_entry(STATE_IA_PD, &entry);
 940
 941                         entry.priority = 0;
 942                         memset(&entry.router, 0, sizeof(entry.router));
 943                 } else if (otype == DHCPV6_OPT_IA_ADDR) {
 944                         struct dhcpv6_ia_addr *addr = (void*)&odata[-4];
 945                         if (olen + 4U < sizeof(*addr))
 946                                 continue;
 947
 948                         entry.preferred = ntohl(addr->preferred);
 949                         entry.valid = ntohl(addr->valid);
 950
 951                         if (entry.preferred > entry.valid)
 952                                 continue;
 953
 954                         entry.length = 128;
 955                         entry.target = addr->addr;
 956
 957 #ifdef EXT_PREFIX_CLASS
 958                         uint16_t stype, slen;
 959                         uint8_t *sdata;
 960                         // Find prefix class, if any
 961                         dhcpv6_for_each_option(&addr[1], odata + olen,
 962                                         stype, slen, sdata)
 963                                 if (stype == DHCPV6_OPT_PREFIX_CLASS && slen == 2)
 964                                         entry.class = sdata[0] << 8 | sdata[1];
 965 #endif
 966
 967                         odhcp6c_update_entry(STATE_IA_NA, &entry);
 968                 }
 969                 if (entry.valid > 0 && timeout > entry.valid)
 970                         timeout = entry.valid;
 971         }
 972
 973         return timeout;
 974 }