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, 1, 30, "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, 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         setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
 161
 162         struct sockaddr_in6 client_addr = { .sin6_family = AF_INET6,
 163                 .sin6_port = htons(DHCPV6_CLIENT_PORT), .sin6_flowinfo = 0 };
 164         if (bind(sock, (struct sockaddr*)&client_addr, sizeof(client_addr)))
 165                 return -1;
 166
 167         return 0;
 168 }
 169
 170
 171 void dhcpv6_set_ia_mode(enum odhcp6c_ia_mode na, enum odhcp6c_ia_mode pd)
 172 {
 173         na_mode = na;
 174         pd_mode = pd;
 175 }
 176
 177
 178 static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
 179 {
 180         // Build FQDN
 181         char fqdn_buf[256];
 182         gethostname(fqdn_buf, sizeof(fqdn_buf));
 183         struct {
 184                 uint16_t type;
 185                 uint16_t len;
 186                 uint8_t flags;
 187                 uint8_t data[256];
 188         } fqdn;
 189         size_t fqdn_len = 5 + dn_comp(fqdn_buf, fqdn.data,
 190                         sizeof(fqdn.data), NULL, NULL);
 191         fqdn.type = htons(DHCPV6_OPT_FQDN);
 192         fqdn.len = htons(fqdn_len - 4);
 193         fqdn.flags = 0;
 194
 195
 196         // Build Client ID
 197         size_t cl_id_len;
 198         void *cl_id = odhcp6c_get_state(STATE_CLIENT_ID, &cl_id_len);
 199
 200         // Get Server ID
 201         size_t srv_id_len;
 202         void *srv_id = odhcp6c_get_state(STATE_SERVER_ID, &srv_id_len);
 203
 204         // Build IA_PDs
 205         size_t ia_pd_entries, ia_pd_len = 0;
 206         struct odhcp6c_entry *e = odhcp6c_get_state(STATE_IA_PD, &ia_pd_entries);
 207         ia_pd_entries /= sizeof(*e);
 208         struct dhcpv6_ia_hdr hdr_ia_pd = {
 209                 htons(DHCPV6_OPT_IA_PD),
 210                 htons(sizeof(hdr_ia_pd) - 4),
 211                 1, 0, 0
 212         };
 213
 214
 215         uint8_t *ia_pd = alloca(ia_pd_entries * (sizeof(struct dhcpv6_ia_prefix) + 10));
 216         for (size_t i = 0; i < ia_pd_entries; ++i) {
 217                 uint8_t ex_len = 0;
 218                 if (e[i].priority > 0)
 219                         ex_len = ((e[i].priority - e[i].length - 1) / 8) + 6;
 220
 221                 struct dhcpv6_ia_prefix p = {
 222                         .type = htons(DHCPV6_OPT_IA_PREFIX),
 223                         .len = htons(sizeof(p) - 4U + ex_len),
 224                         .prefix = e[i].length,
 225                         .addr = e[i].target
 226                 };
 227
 228                 memcpy(ia_pd + ia_pd_len, &p, sizeof(p));
 229                 ia_pd_len += sizeof(p);
 230
 231                 if (ex_len) {
 232                         ia_pd[ia_pd_len++] = 0;
 233                         ia_pd[ia_pd_len++] = DHCPV6_OPT_PD_EXCLUDE;
 234                         ia_pd[ia_pd_len++] = 0;
 235                         ia_pd[ia_pd_len++] = ex_len - 4;
 236                         ia_pd[ia_pd_len++] = e[i].priority;
 237
 238                         uint32_t excl = ntohl(e[i].router.s6_addr32[1]);
 239                         excl >>= (64 - e[i].priority);
 240                         excl <<= 8 - ((e[i].priority - e[i].length) % 8);
 241
 242                         for (size_t i = ex_len - 5; i > 0; --i, excl >>= 8)
 243                                 ia_pd[ia_pd_len + i] = excl & 0xff;
 244                         ia_pd_len += ex_len - 5;
 245                 }
 246         }
 247
 248         struct dhcpv6_ia_prefix pref = {
 249                 .type = htons(DHCPV6_OPT_IA_PREFIX),
 250                 .len = htons(25), .prefix = request_prefix
 251         };
 252         if (request_prefix > 0 && ia_pd_len == 0 && type == DHCPV6_MSG_SOLICIT) {
 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_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_REQUEST)
 374                 timeout = 60;
 375         else if (type == DHCPV6_MSG_RELEASE || type == DHCPV6_MSG_DECLINE)
 376                 timeout = 3;
 377         else if (type == DHCPV6_MSG_UNKNOWN)
 378                 timeout = t1;
 379         else if (type == DHCPV6_MSG_RENEW)
 380                 timeout = (t2 > t1) ? t2 - t1 : 0;
 381         else if (type == DHCPV6_MSG_REBIND)
 382                 timeout = (t3 > t2) ? t3 - t2 : 0;
 383
 384         if (timeout == 0)
 385                 return -1;
 386
 387         syslog(LOG_NOTICE, "Sending %s (timeout %us)", retx->name, (unsigned)timeout);
 388
 389         uint64_t start = odhcp6c_get_milli_time(), round_start = start, elapsed;
 390
 391         // Generate transaction ID
 392         uint8_t trid[3] = {0, 0, 0};
 393         if (type != DHCPV6_MSG_UNKNOWN)
 394                 odhcp6c_random(trid, sizeof(trid));
 395         ssize_t len = -1;
 396         int64_t rto = 0;
 397
 398         do {
 399                 rto = (rto == 0) ? (retx->init_timeo * 1000 +
 400                                 dhcpv6_rand_delay(retx->init_timeo * 1000)) :
 401                                 (2 * rto + dhcpv6_rand_delay(rto));
 402
 403                 if (rto >= retx->max_timeo * 1000)
 404                         rto = retx->max_timeo * 1000 +
 405                                 dhcpv6_rand_delay(retx->max_timeo * 1000);
 406
 407                 // Calculate end for this round and elapsed time
 408                 uint64_t round_end = round_start + rto;
 409                 elapsed = round_start - start;
 410
 411                 // Don't wait too long
 412                 if (round_end - start > timeout * 1000)
 413                         round_end = timeout * 1000 + start;
 414
 415                 // Built and send package
 416                 if (type != DHCPV6_MSG_UNKNOWN)
 417                         dhcpv6_send(type, trid, elapsed / 10);
 418
 419                 // Receive rounds
 420                 for (; len < 0 && round_start < round_end;
 421                                 round_start = odhcp6c_get_milli_time()) {
 422                         // Check for pending signal
 423                         if (odhcp6c_signal_process())
 424                                 return -1;
 425
 426                         // Set timeout for receiving
 427                         uint64_t t = round_end - round_start;
 428                         struct timeval timeout = {t / 1000, (t % 1000) * 1000};
 429                         setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
 430                                         &timeout, sizeof(timeout));
 431
 432                         // Receive cycle
 433                         len = recv(sock, buf, sizeof(buf), 0);
 434
 435                         if (!dhcpv6_response_is_valid(buf, len, trid, type))
 436                                 len = -1;
 437
 438                         if (len > 0) {
 439                                 uint8_t *opt = &buf[4];
 440                                 uint8_t *opt_end = opt + len - 4;
 441
 442                                 round_start = odhcp6c_get_milli_time();
 443                                 elapsed = round_start - start;
 444                                 syslog(LOG_NOTICE, "Got a valid reply after "
 445                                                 "%ums", (unsigned)elapsed);
 446
 447                                 if (retx->handler_reply)
 448                                         len = retx->handler_reply(
 449                                                         type, opt, opt_end);
 450
 451                                 if (len > 0 && round_end - round_start > 1000)
 452                                         round_end = 1000 + round_start;
 453                         }
 454                 }
 455
 456                 // Allow
 457                 if (retx->handler_finish)
 458                         len = retx->handler_finish();
 459         } while (len < 0 && elapsed / 1000 < timeout);
 460
 461         return len;
 462 }
 463
 464
 465 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
 466                 const uint8_t transaction[3], enum dhcpv6_msg type)
 467 {
 468         const struct dhcpv6_header *rep = buf;
 469         if (len < (ssize_t)sizeof(*rep) || memcmp(rep->tr_id,
 470                         transaction, sizeof(rep->tr_id)))
 471                 return false; // Invalid reply
 472
 473         if (type == DHCPV6_MSG_SOLICIT) {
 474                 if (rep->msg_type != DHCPV6_MSG_ADVERT &&
 475                                 rep->msg_type != DHCPV6_MSG_REPLY)
 476                         return false;
 477         } else if (type == DHCPV6_MSG_UNKNOWN) {
 478                 if (!accept_reconfig || rep->msg_type != DHCPV6_MSG_RECONF)
 479                         return false;
 480         } else if (rep->msg_type != DHCPV6_MSG_REPLY) {
 481                 return false;
 482         }
 483
 484         uint8_t *end = ((uint8_t*)buf) + len, *odata;
 485         uint16_t otype, olen;
 486         bool clientid_ok = false, serverid_ok = false, rcauth_ok = false;
 487
 488         size_t client_id_len, server_id_len;
 489         void *client_id = odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 490         void *server_id = odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 491
 492         dhcpv6_for_each_option(&rep[1], end, otype, olen, odata) {
 493                 if (otype == DHCPV6_OPT_CLIENTID) {
 494                         clientid_ok = (olen + 4U == client_id_len) && !memcmp(
 495                                         &odata[-4], client_id, client_id_len);
 496                 } else if (otype == DHCPV6_OPT_SERVERID) {
 497                         serverid_ok = (olen + 4U == server_id_len) && !memcmp(
 498                                         &odata[-4], server_id, server_id_len);
 499                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 500                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 501                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 502                         if (r->protocol != 3 || r->algorithm != 1 || r->reconf_type != 2)
 503                                 continue;
 504
 505                         md5_state_t md5;
 506                         uint8_t serverhash[16], secretbytes[16], hash[16];
 507                         memcpy(serverhash, r->key, sizeof(serverhash));
 508                         memset(r->key, 0, sizeof(r->key));
 509                         memcpy(secretbytes, reconf_key, sizeof(secretbytes));
 510
 511                         for (size_t i = 0; i < sizeof(secretbytes); ++i)
 512                                 secretbytes[i] ^= 0x36;
 513
 514                         md5_init(&md5);
 515                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 516                         md5_append(&md5, buf, len);
 517                         md5_finish(&md5, hash);
 518
 519                         for (size_t i = 0; i < sizeof(secretbytes); ++i) {
 520                                 secretbytes[i] ^= 0x36;
 521                                 secretbytes[i] ^= 0x5c;
 522                         }
 523
 524                         md5_init(&md5);
 525                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 526                         md5_append(&md5, hash, 16);
 527                         md5_finish(&md5, hash);
 528
 529                         rcauth_ok = !memcmp(hash, serverhash, sizeof(hash));
 530                 }
 531         }
 532
 533         if (rep->msg_type == DHCPV6_MSG_RECONF && !rcauth_ok)
 534                 return false;
 535
 536         return clientid_ok && (serverid_ok || server_id_len == 0);
 537 }
 538
 539
 540 int dhcpv6_poll_reconfigure(void)
 541 {
 542         int ret = dhcpv6_request(DHCPV6_MSG_UNKNOWN);
 543         if (ret != -1)
 544                 ret = dhcpv6_request(ret);
 545
 546         return ret;
 547 }
 548
 549
 550 static int dhcpv6_handle_reconfigure(_unused enum dhcpv6_msg orig,
 551                 const void *opt, const void *end)
 552 {
 553         // TODO: should verify the reconfigure message
 554         uint16_t otype, olen;
 555         uint8_t *odata, msg = DHCPV6_MSG_RENEW;
 556         dhcpv6_for_each_option(opt, end, otype, olen, odata)
 557                 if (otype == DHCPV6_OPT_RECONF_MESSAGE && olen == 1 && (
 558                                 odata[0] == DHCPV6_MSG_RENEW ||
 559                                 odata[0] == DHCPV6_MSG_INFO_REQ))
 560                         msg = odata[0];
 561
 562         dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 563         return msg;
 564 }
 565
 566
 567 // Collect all advertised servers
 568 static int dhcpv6_handle_advert(enum dhcpv6_msg orig,
 569                 const void *opt, const void *end)
 570 {
 571         uint16_t olen, otype;
 572         uint8_t *odata;
 573         struct dhcpv6_server_cand cand = {false, false, 0, 0, {0}, NULL, NULL, 0, 0};
 574         bool have_na = false;
 575         int have_pd = 0;
 576
 577         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 578                 if (orig == DHCPV6_MSG_SOLICIT &&
 579                                 (otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA) &&
 580                                 olen > sizeof(struct dhcpv6_ia_hdr)) {
 581                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 582                         dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 583                 }
 584
 585                 if (otype == DHCPV6_OPT_SERVERID && olen <= 130) {
 586                         memcpy(cand.duid, odata, olen);
 587                         cand.duid_len = olen;
 588                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 589                                 && odata[1] == DHCPV6_NoPrefixAvail) {
 590                         cand.preference -= 2000;
 591                 } else if (otype == DHCPV6_OPT_PREF && olen >= 1 &&
 592                                 cand.preference >= 0) {
 593                         cand.preference = odata[0];
 594                 } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
 595                         cand.wants_reconfigure = true;
 596                 } else if (otype == DHCPV6_OPT_IA_PD && request_prefix) {
 597                         struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
 598                         uint8_t *oend = odata + olen, *d;
 599                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d) {
 600                                 if (otype == DHCPV6_OPT_IA_PREFIX && (olen + 4) >=
 601                                                 (uint16_t)sizeof(struct dhcpv6_ia_prefix)) {
 602                                         struct dhcpv6_ia_prefix *p = (struct dhcpv6_ia_prefix*)&odata[-4];
 603                                         have_pd = p->prefix;
 604                                 }
 605                         }
 606                 } else if (otype == DHCPV6_OPT_IA_NA) {
 607                         struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
 608                         uint8_t *oend = odata + olen, *d;
 609                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d)
 610                                 if (otype == DHCPV6_OPT_IA_ADDR)
 611                                         have_na = true;
 612                 }
 613         }
 614
 615         if ((!have_na && na_mode == IA_MODE_FORCE) ||
 616                         (!have_pd && pd_mode == IA_MODE_FORCE))
 617                 return -1;
 618
 619         if (na_mode != IA_MODE_NONE && !have_na) {
 620                 cand.has_noaddravail = true;
 621                 cand.preference -= 1000;
 622         }
 623
 624         if (pd_mode != IA_MODE_NONE) {
 625                 if (have_pd)
 626                         cand.preference += 2000 + (128 - have_pd);
 627                 else
 628                         cand.preference -= 2000;
 629         }
 630
 631         if (cand.duid_len > 0) {
 632                 cand.ia_na = odhcp6c_move_state(STATE_IA_NA, &cand.ia_na_len);
 633                 cand.ia_pd = odhcp6c_move_state(STATE_IA_PD, &cand.ia_pd_len);
 634                 odhcp6c_add_state(STATE_SERVER_CAND, &cand, sizeof(cand));
 635         }
 636
 637         if (orig == DHCPV6_MSG_SOLICIT) {
 638                 odhcp6c_clear_state(STATE_IA_NA);
 639                 odhcp6c_clear_state(STATE_IA_PD);
 640         }
 641
 642         return -1;
 643 }
 644
 645
 646 static int dhcpv6_commit_advert(void)
 647 {
 648         size_t cand_len;
 649         struct dhcpv6_server_cand *c = NULL, *cand =
 650                         odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
 651
 652         bool retry = false;
 653         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 654                 if (cand[i].has_noaddravail)
 655                         retry = true; // We want to try again
 656
 657                 if (!c || c->preference < cand[i].preference)
 658                         c = &cand[i];
 659         }
 660
 661         if (retry && na_mode == IA_MODE_TRY) {
 662                 // We give it a second try without the IA_NA
 663                 na_mode = IA_MODE_NONE;
 664                 return dhcpv6_request(DHCPV6_MSG_SOLICIT);
 665         }
 666
 667         if (c) {
 668                 uint16_t hdr[2] = {htons(DHCPV6_OPT_SERVERID),
 669                                 htons(c->duid_len)};
 670                 odhcp6c_add_state(STATE_SERVER_ID, hdr, sizeof(hdr));
 671                 odhcp6c_add_state(STATE_SERVER_ID, c->duid, c->duid_len);
 672                 accept_reconfig = c->wants_reconfigure;
 673                 odhcp6c_add_state(STATE_IA_NA, c->ia_na, c->ia_na_len);
 674                 odhcp6c_add_state(STATE_IA_PD, c->ia_pd, c->ia_pd_len);
 675         }
 676
 677         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 678                 free(cand[i].ia_na);
 679                 free(cand[i].ia_pd);
 680         }
 681         odhcp6c_clear_state(STATE_SERVER_CAND);
 682
 683         if (!c)
 684                 return -1;
 685         else if (request_prefix || na_mode != IA_MODE_NONE)
 686                 return DHCPV6_STATEFUL;
 687         else
 688                 return DHCPV6_STATELESS;
 689 }
 690
 691
 692 static int dhcpv6_handle_rebind_reply(enum dhcpv6_msg orig,
 693                 const void *opt, const void *end)
 694 {
 695         dhcpv6_handle_advert(orig, opt, end);
 696         if (dhcpv6_commit_advert() < 0) {
 697                 dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 698                 return -1;
 699         }
 700
 701         return dhcpv6_handle_reply(orig, opt, end);
 702 }
 703
 704
 705 static int dhcpv6_handle_reply(enum dhcpv6_msg orig,
 706                 const void *opt, const void *end)
 707 {
 708         uint8_t *odata;
 709         uint16_t otype, olen;
 710
 711         odhcp6c_expire();
 712
 713         if (orig == DHCPV6_MSG_UNKNOWN) {
 714                 static time_t last_update = 0;
 715                 time_t now = odhcp6c_get_milli_time() / 1000;
 716
 717                 uint32_t elapsed = (last_update > 0) ? now - last_update : 0;
 718                 last_update = now;
 719
 720                 t1 -= elapsed;
 721                 t2 -= elapsed;
 722                 t3 -= elapsed;
 723
 724                 if (t1 < 0)
 725                         t1 = 0;
 726
 727                 if (t2 < 0)
 728                         t2 = 0;
 729
 730                 if (t3 < 0)
 731                         t3 = 0;
 732         } else {
 733                 t1 = t2 = t3 = UINT32_MAX;
 734         }
 735
 736         if (orig == DHCPV6_MSG_REQUEST) {
 737                 // Delete NA and PD we have in the state from the Advert
 738                 odhcp6c_clear_state(STATE_IA_NA);
 739                 odhcp6c_clear_state(STATE_IA_PD);
 740         }
 741
 742         if (opt) {
 743                 odhcp6c_clear_state(STATE_DNS);
 744                 odhcp6c_clear_state(STATE_SEARCH);
 745                 odhcp6c_clear_state(STATE_SNTP_IP);
 746                 odhcp6c_clear_state(STATE_SNTP_FQDN);
 747                 odhcp6c_clear_state(STATE_SIP_IP);
 748                 odhcp6c_clear_state(STATE_SIP_FQDN);
 749                 odhcp6c_clear_state(STATE_AFTR_NAME);
 750         }
 751
 752         // Parse and find all matching IAs
 753         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 754                 if ((otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA)
 755                                 && olen > sizeof(struct dhcpv6_ia_hdr)) {
 756                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 757                         uint32_t l_t1 = ntohl(ia_hdr->t1);
 758                         uint32_t l_t2 = ntohl(ia_hdr->t2);
 759
 760                         // Test ID and T1-T2 validity
 761                         if (ia_hdr->iaid != 1 || l_t2 < l_t1)
 762                                 continue;
 763
 764                         int error = 0;
 765                         uint16_t stype, slen;
 766                         uint8_t *sdata;
 767                         // Test status and bail if error
 768                         dhcpv6_for_each_option(&ia_hdr[1], odata + olen,
 769                                         stype, slen, sdata)
 770                                 if (stype == DHCPV6_OPT_STATUS && slen >= 2)
 771                                         error = ((int)sdata[0]) << 8 | ((int)sdata[1]);
 772
 773                         if (error) {
 774                                 syslog(LOG_WARNING, "Server returned IAID status %i!", error);
 775                                 if (error != 2)
 776                                         raise(SIGUSR2);
 777                                 break;
 778                         }
 779
 780                         uint32_t n = dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 781
 782                         if (!l_t1)
 783                                 l_t1 = 300;
 784
 785                         if (!l_t2)
 786                                 l_t2 = 600;
 787
 788                         if (n < t3)
 789                                 t3 = n;
 790
 791                         // Update times
 792                         if (l_t1 > 0 && t1 > l_t1)
 793                                 t1 = l_t1;
 794
 795                         if (l_t2 > 0 && t2 > l_t2)
 796                                 t2 = l_t2;
 797
 798                 } else if (otype == DHCPV6_OPT_DNS_SERVERS) {
 799                         if (olen % 16 == 0)
 800                                 odhcp6c_add_state(STATE_DNS, odata, olen);
 801                 } else if (otype == DHCPV6_OPT_DNS_DOMAIN) {
 802                         odhcp6c_add_state(STATE_SEARCH, odata, olen);
 803                 } else if (otype == DHCPV6_OPT_NTP_SERVER) {
 804                         uint16_t stype, slen;
 805                         uint8_t *sdata;
 806                         // Test status and bail if error
 807                         dhcpv6_for_each_option(odata, odata + olen,
 808                                         stype, slen, sdata) {
 809                                 if (slen == 16 && (stype == NTP_MC_ADDR ||
 810                                                 stype == NTP_SRV_ADDR))
 811                                         odhcp6c_add_state(STATE_SNTP_IP,
 812                                                         sdata, slen);
 813                                 else if (slen > 0 && stype == NTP_SRV_FQDN)
 814                                         odhcp6c_add_state(STATE_SNTP_FQDN,
 815                                                         sdata, slen);
 816                         }
 817                 } else if (otype == DHCPV6_OPT_SIP_SERVER_A) {
 818                         if (olen == 16)
 819                                 odhcp6c_add_state(STATE_SIP_IP, odata, olen);
 820                 } else if (otype == DHCPV6_OPT_SIP_SERVER_D) {
 821                         odhcp6c_add_state(STATE_SIP_FQDN, odata, olen);
 822                 } else if (otype == DHCPV6_OPT_INFO_REFRESH && olen >= 4) {
 823                         uint32_t refresh = ntohl(*((uint32_t*)odata));
 824                         if (refresh < (uint32_t)t1)
 825                                 t1 = refresh;
 826                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 827                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 828                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 829                         if (r->protocol == 3 && r->algorithm == 1 &&
 830                                         r->reconf_type == 1)
 831                                 memcpy(reconf_key, r->key, sizeof(r->key));
 832                 } else if (otype == DHCPV6_OPT_AFTR_NAME && olen > 3) {
 833                         size_t cur_len;
 834                         odhcp6c_get_state(STATE_AFTR_NAME, &cur_len);
 835                         if (cur_len == 0)
 836                                 odhcp6c_add_state(STATE_AFTR_NAME, odata, olen);
 837                 } else if (otype != DHCPV6_OPT_CLIENTID &&
 838                                 otype != DHCPV6_OPT_SERVERID) {
 839                         odhcp6c_add_state(STATE_CUSTOM_OPTS,
 840                                         &odata[-4], olen + 4);
 841                 }
 842         }
 843
 844         if (t1 == UINT32_MAX)
 845                 t1 = 300;
 846
 847         if (t2 == UINT32_MAX)
 848                 t2 = 600;
 849
 850         if (t3 == UINT32_MAX)
 851                 t3 = 3600;
 852
 853         return true;
 854 }
 855
 856
 857 static uint32_t dhcpv6_parse_ia(void *opt, void *end)
 858 {
 859         uint32_t timeout = UINT32_MAX; // Minimum timeout
 860         uint16_t otype, olen;
 861         uint8_t *odata;
 862
 863         // Update address IA
 864         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 865                 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, 0, 0,
 866                                 IN6ADDR_ANY_INIT, 0, 0, 0};
 867
 868                 if (otype == DHCPV6_OPT_IA_PREFIX) {
 869                         struct dhcpv6_ia_prefix *prefix = (void*)&odata[-4];
 870                         if (olen + 4U < sizeof(*prefix))
 871                                 continue;
 872
 873                         entry.valid = ntohl(prefix->valid);
 874                         entry.preferred = ntohl(prefix->preferred);
 875
 876                         if (entry.preferred > entry.valid)
 877                                 continue;
 878
 879                         entry.length = prefix->prefix;
 880                         entry.target = prefix->addr;
 881                         uint16_t stype, slen;
 882                         uint8_t *sdata;
 883
 884 #ifdef EXT_PREFIX_CLASS
 885                         // Find prefix class, if any
 886                         dhcpv6_for_each_option(&prefix[1], odata + olen,
 887                                         stype, slen, sdata)
 888                                 if (stype == DHCPV6_OPT_PREFIX_CLASS && slen == 2)
 889                                         entry.class = sdata[0] << 8 | sdata[1];
 890 #endif
 891
 892                         // Parse PD-exclude
 893                         bool ok = true;
 894                         dhcpv6_for_each_option(odata + sizeof(*prefix) - 4U,
 895                                         odata + olen, stype, slen, sdata) {
 896                                 if (stype != DHCPV6_OPT_PD_EXCLUDE || slen < 2)
 897                                         continue;
 898
 899                                 uint8_t elen = sdata[0];
 900                                 if (elen > 64)
 901                                         elen = 64;
 902
 903                                 if (elen <= 32 || elen <= entry.length) {
 904                                         ok = false;
 905                                         continue;
 906                                 }
 907
 908
 909                                 uint8_t bytes = ((elen - entry.length - 1) / 8) + 1;
 910                                 if (slen <= bytes) {
 911                                         ok = false;
 912                                         continue;
 913                                 }
 914
 915                                 uint32_t exclude = 0;
 916                                 do {
 917                                         exclude = exclude << 8 | sdata[bytes];
 918                                 } while (--bytes);
 919
 920                                 exclude >>= 8 - ((elen - entry.length) % 8);
 921                                 exclude <<= 64 - elen;
 922
 923                                 // Abusing router & priority fields for exclusion
 924                                 entry.router = entry.target;
 925                                 entry.router.s6_addr32[1] |= htonl(exclude);
 926                                 entry.priority = elen;
 927                         }
 928
 929                         if (ok)
 930                                 odhcp6c_update_entry(STATE_IA_PD, &entry);
 931
 932                         entry.priority = 0;
 933                         memset(&entry.router, 0, sizeof(entry.router));
 934                 } else if (otype == DHCPV6_OPT_IA_ADDR) {
 935                         struct dhcpv6_ia_addr *addr = (void*)&odata[-4];
 936                         if (olen + 4U < sizeof(*addr))
 937                                 continue;
 938
 939                         entry.preferred = ntohl(addr->preferred);
 940                         entry.valid = ntohl(addr->valid);
 941
 942                         if (entry.preferred > entry.valid)
 943                                 continue;
 944
 945                         entry.length = 128;
 946                         entry.target = addr->addr;
 947
 948 #ifdef EXT_PREFIX_CLASS
 949                         uint16_t stype, slen;
 950                         uint8_t *sdata;
 951                         // Find prefix class, if any
 952                         dhcpv6_for_each_option(&addr[1], odata + olen,
 953                                         stype, slen, sdata)
 954                                 if (stype == DHCPV6_OPT_PREFIX_CLASS && slen == 2)
 955                                         entry.class = sdata[0] << 8 | sdata[1];
 956 #endif
 957
 958                         odhcp6c_update_entry(STATE_IA_NA, &entry);
 959                 }
 960                 if (entry.valid > 0 && timeout > entry.valid)
 961                         timeout = entry.valid;
 962         }
 963
 964         return timeout;
 965 }