src/dhcpv4.c

   1 /**
   2  * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
   3  * Copyright (C) 2016 Hans Dedecker <dedeckeh@gmail.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License v2 as published by
   7  * the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  *
  15  */
  16
  17 #include <time.h>
  18 #include <errno.h>
  19 #include <fcntl.h>
  20 #include <unistd.h>
  21 #include <stddef.h>
  22 #include <stdlib.h>
  23 #include <resolv.h>
  24 #include <limits.h>
  25 #include <net/if.h>
  26 #include <net/if_arp.h>
  27 #include <netinet/ip.h>
  28 #include <sys/ioctl.h>
  29 #include <sys/timerfd.h>
  30 #include <arpa/inet.h>
  31
  32 #include <libubox/md5.h>
  33
  34 #include "odhcpd.h"
  35 #include "dhcpv4.h"
  36 #include "dhcpv6.h"
  37
  38 static void dhcpv4_netevent_cb(unsigned long event, struct netevent_handler_info *info);
  39 static int setup_dhcpv4_addresses(struct interface *iface);
  40 static void update_static_assignments(struct interface *iface);
  41 static bool addr_is_fr_ip(struct interface *iface, struct in_addr *addr);
  42 static void valid_until_cb(struct uloop_timeout *event);
  43 static void handle_addrlist_change(struct interface *iface);
  44 static void free_dhcpv4_assignment(struct dhcpv4_assignment *a);
  45 static void dhcpv4_fr_start(struct dhcpv4_assignment *a);
  46 static void dhcpv4_fr_rand_delay(struct dhcpv4_assignment *a);
  47 static void dhcpv4_fr_stop(struct dhcpv4_assignment *a);
  48 static void handle_dhcpv4(void *addr, void *data, size_t len,
  49                 struct interface *iface, void *dest_addr);
  50 static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
  51                 enum dhcpv4_msg msg, const uint8_t *mac, const uint32_t reqaddr,
  52                 uint32_t *leasetime, const char *hostname, const size_t hostname_len,
  53                 const bool accept_fr_nonce, bool *incl_fr_opt, uint32_t *fr_serverid);
  54
  55 static struct netevent_handler dhcpv4_netevent_handler = { .cb = dhcpv4_netevent_cb, };
  56 static struct uloop_timeout valid_until_timeout = {.cb = valid_until_cb};
  57 static uint32_t serial = 0;
  58
  59 struct odhcpd_ref_ip {
  60         struct list_head head;
  61         int ref_cnt;
  62         struct odhcpd_ipaddr addr;
  63 };
  64
  65 /* Create socket and register events */
  66 int dhcpv4_init(void)
  67 {
  68         uloop_timeout_set(&valid_until_timeout, 1000);
  69         netlink_add_netevent_handler(&dhcpv4_netevent_handler);
  70
  71         return 0;
  72 }
  73
  74 int dhcpv4_setup_interface(struct interface *iface, bool enable)
  75 {
  76         int ret = 0;
  77
  78         if (iface->dhcpv4_event.uloop.fd > 0) {
  79                 uloop_fd_delete(&iface->dhcpv4_event.uloop);
  80                 close(iface->dhcpv4_event.uloop.fd);
  81                 iface->dhcpv4_event.uloop.fd = -1;
  82         }
  83
  84         if (iface->dhcpv4 && enable) {
  85                 struct sockaddr_in bind_addr = {AF_INET, htons(DHCPV4_SERVER_PORT),
  86                                         {INADDR_ANY}, {0}};
  87                 int val = 1;
  88
  89                 if (!iface->dhcpv4_assignments.next)
  90                         INIT_LIST_HEAD(&iface->dhcpv4_assignments);
  91
  92                 if (!iface->dhcpv4_fr_ips.next)
  93                         INIT_LIST_HEAD(&iface->dhcpv4_fr_ips);
  94
  95                 iface->dhcpv4_event.uloop.fd = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
  96                 if (iface->dhcpv4_event.uloop.fd < 0) {
  97                         syslog(LOG_ERR, "socket(AF_INET): %m");
  98                         ret = -1;
  99                         goto out;
 100                 }
 101
 102                 /* Basic IPv4 configuration */
 103                 if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_REUSEADDR,
 104                                         &val, sizeof(val)) < 0) {
 105                         syslog(LOG_ERR, "setsockopt(SO_REUSEADDR): %m");
 106                         ret = -1;
 107                         goto out;
 108                 }
 109
 110                 if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_BROADCAST,
 111                                         &val, sizeof(val)) < 0) {
 112                         syslog(LOG_ERR, "setsockopt(SO_BROADCAST): %m");
 113                         ret = -1;
 114                         goto out;
 115                 }
 116
 117                 if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_PKTINFO,
 118                                         &val, sizeof(val)) < 0) {
 119                         syslog(LOG_ERR, "setsockopt(IP_PKTINFO): %m");
 120                         ret = -1;
 121                         goto out;
 122                 }
 123
 124                 val = IPTOS_PREC_INTERNETCONTROL;
 125                 if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_TOS,
 126                                         &val, sizeof(val)) < 0) {
 127                         syslog(LOG_ERR, "setsockopt(IP_TOS): %m");
 128                         ret = -1;
 129                         goto out;
 130                 }
 131
 132                 val = IP_PMTUDISC_DONT;
 133                 if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_MTU_DISCOVER,
 134                                         &val, sizeof(val)) < 0) {
 135                         syslog(LOG_ERR, "setsockopt(IP_MTU_DISCOVER): %m");
 136                         ret = -1;
 137                         goto out;
 138                 }
 139
 140                 if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_BINDTODEVICE,
 141                                         iface->ifname, strlen(iface->ifname)) < 0) {
 142                         syslog(LOG_ERR, "setsockopt(SO_BINDTODEVICE): %m");
 143                         ret = -1;
 144                         goto out;
 145                 }
 146
 147                 if (bind(iface->dhcpv4_event.uloop.fd, (struct sockaddr*)&bind_addr,
 148                                         sizeof(bind_addr)) < 0) {
 149                         syslog(LOG_ERR, "bind(): %m");
 150                         ret = -1;
 151                         goto out;
 152                 }
 153
 154                 if (setup_dhcpv4_addresses(iface) < 0) {
 155                         ret = -1;
 156                         goto out;
 157                 }
 158
 159                 iface->dhcpv4_event.handle_dgram = handle_dhcpv4;
 160                 odhcpd_register(&iface->dhcpv4_event);
 161
 162                 update_static_assignments(iface);
 163         } else if (iface->dhcpv4_assignments.next) {
 164                 while (!list_empty(&iface->dhcpv4_assignments))
 165                         free_dhcpv4_assignment(list_first_entry(&iface->dhcpv4_assignments,
 166                                                         struct dhcpv4_assignment, head));
 167         }
 168
 169 out:
 170         if (ret < 0 && iface->dhcpv4_event.uloop.fd > 0) {
 171                 close(iface->dhcpv4_event.uloop.fd);
 172                 iface->dhcpv4_event.uloop.fd = -1;
 173         }
 174
 175         return ret;
 176 }
 177
 178
 179 static void dhcpv4_netevent_cb(unsigned long event, struct netevent_handler_info *info)
 180 {
 181         struct interface *iface = info->iface;
 182
 183         if (!iface || iface->dhcpv4 == MODE_DISABLED)
 184                 return;
 185
 186         switch (event) {
 187         case NETEV_IFINDEX_CHANGE:
 188                 dhcpv4_setup_interface(iface, true);
 189                 break;
 190         case NETEV_ADDRLIST_CHANGE:
 191                 handle_addrlist_change(iface);
 192                 break;
 193         default:
 194                 break;
 195         }
 196 }
 197
 198 static struct dhcpv4_assignment *find_assignment_by_hwaddr(struct interface *iface, const uint8_t *hwaddr)
 199 {
 200         struct dhcpv4_assignment *a;
 201
 202         list_for_each_entry(a, &iface->dhcpv4_assignments, head)
 203                 if (!memcmp(a->hwaddr, hwaddr, 6))
 204                         return a;
 205
 206         return NULL;
 207 }
 208
 209 static struct dhcpv4_assignment *find_assignment_by_addr(struct interface *iface, const uint32_t addr)
 210 {
 211         struct dhcpv4_assignment *a;
 212
 213         list_for_each_entry(a, &iface->dhcpv4_assignments, head)
 214                 if (a->addr == addr)
 215                         return a;
 216
 217         return NULL;
 218 }
 219
 220 static int setup_dhcpv4_addresses(struct interface *iface)
 221 {
 222         iface->dhcpv4_start_ip.s_addr = INADDR_ANY;
 223         iface->dhcpv4_end_ip.s_addr = INADDR_ANY;
 224         iface->dhcpv4_local.s_addr = INADDR_ANY;
 225         iface->dhcpv4_bcast.s_addr = INADDR_ANY;
 226         iface->dhcpv4_mask.s_addr = INADDR_ANY;
 227
 228         /* Sanity checks */
 229         if (iface->dhcpv4_start.s_addr & htonl(0xffff0000) ||
 230             iface->dhcpv4_end.s_addr & htonl(0xffff0000) ||
 231             ntohl(iface->dhcpv4_start.s_addr) > ntohl(iface->dhcpv4_end.s_addr)) {
 232                 syslog(LOG_ERR, "Invalid DHCP range for %s", iface->name);
 233                 return -1;
 234         }
 235
 236         if (!iface->addr4_len) {
 237                 syslog(LOG_WARNING, "No network(s) available on %s", iface->name);
 238                 return -1;
 239         }
 240
 241         uint32_t start = ntohl(iface->dhcpv4_start.s_addr);
 242         uint32_t end = ntohl(iface->dhcpv4_end.s_addr);
 243
 244         for (size_t i = 0; i < iface->addr4_len && start && end; i++) {
 245                 struct in_addr *addr = &iface->addr4[i].addr.in;
 246                 struct in_addr mask;
 247
 248                 if (addr_is_fr_ip(iface, addr))
 249                         continue;
 250
 251                 odhcpd_bitlen2netmask(false, iface->addr4[i].prefix, &mask);
 252                 if ((start & ntohl(~mask.s_addr)) == start &&
 253                             (end & ntohl(~mask.s_addr)) == end) {
 254                         iface->dhcpv4_start_ip.s_addr = htonl(start) |
 255                                                         (addr->s_addr & mask.s_addr);
 256                         iface->dhcpv4_end_ip.s_addr = htonl(end) |
 257                                                         (addr->s_addr & mask.s_addr);
 258                         iface->dhcpv4_local = *addr;
 259                         iface->dhcpv4_bcast = iface->addr4[i].broadcast;
 260                         iface->dhcpv4_mask = mask;
 261                         return 0;
 262                 }
 263         }
 264
 265         /* Don't allocate IP range for subnets bigger than 28 */
 266         if (iface->addr4[0].prefix > 28) {
 267                 syslog(LOG_WARNING, "Auto allocation of DHCP range fails on %s", iface->name);
 268                 return -1;
 269         }
 270
 271         iface->dhcpv4_local = iface->addr4[0].addr.in;
 272         iface->dhcpv4_bcast = iface->addr4[0].broadcast;
 273         odhcpd_bitlen2netmask(false, iface->addr4[0].prefix, &iface->dhcpv4_mask);
 274         end = start = iface->dhcpv4_local.s_addr & iface->dhcpv4_mask.s_addr;
 275
 276         /* Auto allocate ranges */
 277         if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffff00) {
 278                 iface->dhcpv4_start_ip.s_addr = start | htonl(100);
 279                 iface->dhcpv4_end_ip.s_addr = end | htonl(250);
 280         } else if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffffc0) {
 281                 iface->dhcpv4_start_ip.s_addr = start | htonl(10);
 282                 iface->dhcpv4_end_ip.s_addr = end | htonl(60);
 283         } else if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffffe0) {
 284                 iface->dhcpv4_start_ip.s_addr = start | htonl(10);
 285                 iface->dhcpv4_end_ip.s_addr = end | htonl(30);
 286         } else {
 287                 iface->dhcpv4_start_ip.s_addr = start | htonl(3);
 288                 iface->dhcpv4_end_ip.s_addr = end | htonl(12);
 289         }
 290
 291         return 0;
 292 }
 293
 294 static void update_static_assignments(struct interface *iface)
 295 {
 296         struct dhcpv4_assignment *a, *c;
 297
 298         /* Cleanup static entries not belonging to the network */
 299         list_for_each_entry_safe(a, c, &iface->dhcpv4_assignments, head) {
 300                 if ((a->flags & OAF_STATIC) &&
 301                                 ((a->addr & iface->dhcpv4_mask.s_addr) !=
 302                                  (iface->dhcpv4_start.s_addr & iface->dhcpv4_mask.s_addr)))
 303                         free_dhcpv4_assignment(a);
 304         }
 305
 306         /* Parse static entries */
 307         struct lease *lease;
 308         list_for_each_entry(lease, &leases, head) {
 309                 if ((iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr) !=
 310                                 (lease->ipaddr.s_addr & iface->dhcpv4_mask.s_addr)) {
 311                         continue;
 312                 }
 313
 314                 a = find_assignment_by_hwaddr(iface, lease->mac.ether_addr_octet);
 315
 316                 if (!a) {
 317                         /* Check if there's an assignment with the specified IP address */
 318                         if (find_assignment_by_addr(iface, lease->ipaddr.s_addr))
 319                                 continue;
 320
 321                         /* Construct entry */
 322                         a = calloc(1, sizeof(*a));
 323                         if (!a) {
 324                                 syslog(LOG_ERR, "Calloc failed for static lease on %s", iface->name);
 325                                 continue;
 326                         }
 327                         memcpy(a->hwaddr, lease->mac.ether_addr_octet, sizeof(a->hwaddr));
 328                 }
 329
 330                 a->leasetime = lease->dhcpv4_leasetime;
 331
 332                 a->addr = lease->ipaddr.s_addr;
 333                 /* Static assignment */
 334                 a->flags |= OAF_STATIC;
 335                 /* Infinite valid */
 336                 a->valid_until = 0;
 337                 a->iface = iface;
 338                 if (lease->hostname[0]) {
 339                         free(a->hostname);
 340                         a->hostname = strdup(lease->hostname);
 341                 }
 342
 343                 /* Assign to all interfaces */
 344                 list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
 345                         if (ntohl(c->addr) > ntohl(a->addr)) {
 346                                 list_add_tail(&a->head, &c->head);
 347                                 break;
 348                         }
 349                 }
 350
 351                 if (&c->head == &iface->dhcpv4_assignments)
 352                         list_add(&a->head, &iface->dhcpv4_assignments);
 353         }
 354 }
 355
 356 static void inc_ref_cnt_ip(struct odhcpd_ref_ip **ptr, struct odhcpd_ref_ip *ip)
 357 {
 358         *ptr = ip;
 359         ip->ref_cnt++;
 360 }
 361
 362 static void decr_ref_cnt_ip(struct odhcpd_ref_ip **ptr, struct interface *iface)
 363 {
 364         struct odhcpd_ref_ip *ip = *ptr;
 365
 366         if (--ip->ref_cnt == 0) {
 367                 netlink_setup_addr(&ip->addr, iface->ifindex, false, false);
 368
 369                 list_del(&ip->head);
 370                 free(ip);
 371         }
 372
 373         *ptr = NULL;
 374 }
 375
 376 static bool addr_is_fr_ip(struct interface *iface, struct in_addr *addr)
 377 {
 378         struct odhcpd_ref_ip *p;
 379
 380         list_for_each_entry(p, &iface->dhcpv4_fr_ips, head) {
 381                 if (addr->s_addr == p->addr.addr.in.s_addr)
 382                         return true;
 383         }
 384
 385         return false;
 386 }
 387
 388 static bool leases_require_fr(struct interface *iface, struct odhcpd_ipaddr *addr,
 389                                 uint32_t mask)
 390 {
 391         struct dhcpv4_assignment *a = NULL;
 392         struct odhcpd_ref_ip *fr_ip = NULL;
 393
 394         list_for_each_entry(a, &iface->dhcpv4_assignments, head) {
 395                 if ((a->accept_fr_nonce || iface->dhcpv4_forcereconf) &&
 396                     !a->fr_ip &&
 397                     ((a->addr & mask) == (addr->addr.in.s_addr & mask))) {
 398                         if (!fr_ip) {
 399                                 fr_ip = calloc(1, sizeof(*fr_ip));
 400                                 if (!fr_ip)
 401                                         break;
 402
 403                                 list_add(&fr_ip->head, &iface->dhcpv4_fr_ips);
 404                                 fr_ip->addr = *addr;
 405                         }
 406                         inc_ref_cnt_ip(&a->fr_ip, fr_ip);
 407                 }
 408         }
 409
 410         return fr_ip ? true : false;
 411 }
 412
 413 static void valid_until_cb(struct uloop_timeout *event)
 414 {
 415         time_t now = odhcpd_time();
 416         struct interface *iface;
 417         list_for_each_entry(iface, &interfaces, head) {
 418                 if (iface->dhcpv4 != MODE_SERVER || iface->dhcpv4_assignments.next == NULL)
 419                         continue;
 420
 421                 struct dhcpv4_assignment *a, *n;
 422                 list_for_each_entry_safe(a, n, &iface->dhcpv4_assignments, head) {
 423                         if (!INFINITE_VALID(a->valid_until) && a->valid_until < now)
 424                                 free_dhcpv4_assignment(a);
 425                 }
 426         }
 427         uloop_timeout_set(event, 1000);
 428 }
 429
 430 static void handle_addrlist_change(struct interface *iface)
 431 {
 432         struct odhcpd_ipaddr ip;
 433         struct odhcpd_ref_ip *a;
 434         struct dhcpv4_assignment *c;
 435         uint32_t mask = iface->dhcpv4_mask.s_addr;
 436
 437         memset(&ip, 0, sizeof(ip));
 438         ip.addr.in = iface->dhcpv4_local;
 439         ip.prefix = odhcpd_netmask2bitlen(false, &iface->dhcpv4_mask);
 440         ip.broadcast = iface->dhcpv4_bcast;
 441
 442         setup_dhcpv4_addresses(iface);
 443
 444         if ((ip.addr.in.s_addr & mask) ==
 445             (iface->dhcpv4_local.s_addr & iface->dhcpv4_mask.s_addr))
 446                 return;
 447
 448         if (ip.addr.in.s_addr && !leases_require_fr(iface, &ip, mask))
 449                 return;
 450
 451         if (iface->dhcpv4_local.s_addr == INADDR_ANY || list_empty(&iface->dhcpv4_fr_ips))
 452                 return;
 453
 454         a = list_first_entry(&iface->dhcpv4_fr_ips, struct odhcpd_ref_ip, head);
 455
 456         if (netlink_setup_addr(&a->addr, iface->ifindex, false, true)) {
 457                 syslog(LOG_ERR, "Failed to add ip address on %s", iface->name);
 458                 return;
 459         }
 460
 461         list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
 462                 if ((c->flags & OAF_BOUND) && c->fr_ip && !c->fr_cnt) {
 463                         if (c->accept_fr_nonce || iface->dhcpv4_forcereconf)
 464                                 dhcpv4_fr_rand_delay(c);
 465                         else
 466                                 dhcpv4_fr_stop(c);
 467                 }
 468         }
 469 }
 470
 471 static char *dhcpv4_msg_to_string(uint8_t reqmsg)
 472 {
 473         switch (reqmsg) {
 474         case (DHCPV4_MSG_DISCOVER):
 475                 return "DHCPV4_MSG_DISCOVER";
 476         case (DHCPV4_MSG_OFFER):
 477                 return "DHCPV4_MSG_OFFER";
 478         case (DHCPV4_MSG_REQUEST):
 479                 return "DHCPV4_MSG_REQUEST";
 480         case (DHCPV4_MSG_DECLINE):
 481                 return "DHCPV4_MSG_DECLINE";
 482         case (DHCPV4_MSG_ACK):
 483                 return "DHCPV4_MSG_ACK";
 484         case (DHCPV4_MSG_NAK):
 485                 return "DHCPV4_MSG_NAK";
 486         case (DHCPV4_MSG_RELEASE):
 487                 return "DHCPV4_MSG_RELEASE";
 488         case (DHCPV4_MSG_INFORM):
 489                 return "DHCPV4_MSG_INFORM";
 490         case (DHCPV4_MSG_FORCERENEW):
 491                 return "DHCPV4_MSG_FORCERENEW";
 492         default:
 493                 return "UNKNOWN";
 494         }
 495 }
 496
 497 static void free_dhcpv4_assignment(struct dhcpv4_assignment *a)
 498 {
 499         if (a->head.next)
 500                 list_del(&a->head);
 501
 502         if (a->fr_ip)
 503                 dhcpv4_fr_stop(a);
 504
 505         free(a->hostname);
 506         free(a);
 507 }
 508
 509 static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie,
 510                 uint8_t type, uint8_t len, const void *data)
 511 {
 512         uint8_t *c = *cookie;
 513         uint8_t *end = (uint8_t *)msg + sizeof(*msg);
 514
 515         if (*cookie + 2 + len > end)
 516                 return;
 517
 518         *c++ = type;
 519         *c++ = len;
 520         memcpy(c, data, len);
 521
 522         *cookie = c + len;
 523 }
 524
 525 static void dhcpv4_fr_send(struct dhcpv4_assignment *a)
 526 {
 527         struct dhcpv4_message fr_msg = {
 528                 .op = DHCPV4_BOOTREPLY,
 529                 .htype = 1,
 530                 .hlen = 6,
 531                 .hops = 0,
 532                 .secs = 0,
 533                 .flags = 0,
 534                 .ciaddr = {INADDR_ANY},
 535                 .yiaddr = {INADDR_ANY},
 536                 .siaddr = {INADDR_ANY},
 537                 .giaddr = {INADDR_ANY},
 538                 .chaddr = {0},
 539                 .sname = {0},
 540                 .file = {0},
 541         };
 542         struct dhcpv4_auth_forcerenew *auth_o, auth = {
 543                 .protocol = 3,
 544                 .algorithm = 1,
 545                 .rdm = 0,
 546                 .replay = {htonl(time(NULL)), htonl(++serial)},
 547                 .type = 2,
 548                 .key = {0},
 549         };
 550         struct interface *iface = a->iface;
 551
 552         odhcpd_urandom(&fr_msg.xid, sizeof(fr_msg.xid));
 553         memcpy(fr_msg.chaddr, a->hwaddr, fr_msg.hlen);
 554
 555         fr_msg.options[0] = 0x63;
 556         fr_msg.options[1] = 0x82;
 557         fr_msg.options[2] = 0x53;
 558         fr_msg.options[3] = 0x63;
 559
 560         uint8_t *cookie = &fr_msg.options[4];
 561         uint8_t msg = DHCPV4_MSG_FORCERENEW;
 562
 563         dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg);
 564         if (a->accept_fr_nonce) {
 565                 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_AUTHENTICATION, sizeof(auth), &auth);
 566                 auth_o = (struct dhcpv4_auth_forcerenew *)(cookie - sizeof(auth));
 567                 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_END, 0, NULL);
 568
 569                 md5_ctx_t md5;
 570                 uint8_t secretbytes[64];
 571                 memset(secretbytes, 0, sizeof(secretbytes));
 572                 memcpy(secretbytes, a->key, sizeof(a->key));
 573
 574                 for (size_t i = 0; i < sizeof(secretbytes); ++i)
 575                         secretbytes[i] ^= 0x36;
 576
 577                 md5_begin(&md5);
 578                 md5_hash(secretbytes, sizeof(secretbytes), &md5);
 579                 md5_hash(&fr_msg, sizeof(fr_msg), &md5);
 580                 md5_end(auth_o->key, &md5);
 581
 582                 for (size_t i = 0; i < sizeof(secretbytes); ++i) {
 583                         secretbytes[i] ^= 0x36;
 584                         secretbytes[i] ^= 0x5c;
 585                 }
 586
 587                 md5_begin(&md5);
 588                 md5_hash(secretbytes, sizeof(secretbytes), &md5);
 589                 md5_hash(auth_o->key, sizeof(auth_o->key), &md5);
 590                 md5_end(auth_o->key, &md5);
 591         } else {
 592                 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_SERVERID, 4,
 593                                 &a->fr_ip->addr.addr.in.s_addr);
 594                 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_END, 0, NULL);
 595         }
 596
 597         struct sockaddr_in dest;
 598         memset(&dest, 0, sizeof(dest));
 599         dest.sin_family = AF_INET;
 600         dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 601         dest.sin_addr.s_addr = a->addr;
 602
 603         if (sendto(iface->dhcpv4_event.uloop.fd, &fr_msg, sizeof(fr_msg),
 604                         MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest)) < 0)
 605                 syslog(LOG_ERR, "Failed to send %s to %s - %s: %m", dhcpv4_msg_to_string(msg),
 606                         odhcpd_print_mac(a->hwaddr, sizeof(a->hwaddr)), inet_ntoa(dest.sin_addr));
 607         else
 608                 syslog(LOG_WARNING, "Sent %s to %s - %s", dhcpv4_msg_to_string(msg),
 609                         odhcpd_print_mac(a->hwaddr, sizeof(a->hwaddr)), inet_ntoa(dest.sin_addr));
 610 }
 611
 612 static void dhcpv4_fr_timer(struct uloop_timeout *event)
 613 {
 614         struct dhcpv4_assignment *a = container_of(event, struct dhcpv4_assignment, fr_timer);
 615
 616         if (a->fr_cnt > 0 && a->fr_cnt < 8) {
 617                 dhcpv4_fr_send(a);
 618                 uloop_timeout_set(&a->fr_timer, 1000 << a->fr_cnt);
 619                 a->fr_cnt++;
 620         } else
 621                 dhcpv4_fr_stop(a);
 622 }
 623
 624 static void dhcpv4_fr_start(struct dhcpv4_assignment *a)
 625 {
 626         uloop_timeout_set(&a->fr_timer, 1000 << a->fr_cnt);
 627         a->fr_timer.cb = dhcpv4_fr_timer;
 628         a->fr_cnt++;
 629
 630         dhcpv4_fr_send(a);
 631 }
 632
 633 static void dhcpv4_fr_delay_timer(struct uloop_timeout *event)
 634 {
 635         struct dhcpv4_assignment *a = container_of(event, struct dhcpv4_assignment, fr_timer);
 636         struct interface *iface = a->iface;
 637
 638         (iface->dhcpv4_event.uloop.fd == -1 ? dhcpv4_fr_rand_delay(a) : dhcpv4_fr_start(a));
 639 }
 640
 641 static void dhcpv4_fr_rand_delay(struct dhcpv4_assignment *a)
 642 {
 643 #define MIN_DELAY   500
 644 #define MAX_FUZZ    500
 645         int msecs;
 646
 647         odhcpd_urandom(&msecs, sizeof(msecs));
 648
 649         msecs = labs(msecs)%MAX_FUZZ + MIN_DELAY;
 650
 651         uloop_timeout_set(&a->fr_timer, msecs);
 652         a->fr_timer.cb = dhcpv4_fr_delay_timer;
 653 }
 654
 655 static void dhcpv4_fr_stop(struct dhcpv4_assignment *a)
 656 {
 657         uloop_timeout_cancel(&a->fr_timer);
 658         decr_ref_cnt_ip(&a->fr_ip, a->iface);
 659         a->fr_cnt = 0;
 660         a->fr_timer.cb = NULL;
 661 }
 662
 663 /* Handler for DHCPv4 messages */
 664 static void handle_dhcpv4(void *addr, void *data, size_t len,
 665                 struct interface *iface, _unused void *dest_addr)
 666 {
 667         if (!iface->dhcpv4)
 668                 return;
 669
 670         struct dhcpv4_message *req = data;
 671         if (len < offsetof(struct dhcpv4_message, options) + 4 ||
 672                         req->op != DHCPV4_BOOTREQUEST || req->hlen != 6)
 673                 return;
 674
 675
 676         syslog(LOG_NOTICE, "Got DHCPv4 request on %s", iface->name);
 677
 678         if (!iface->dhcpv4_start_ip.s_addr && !iface->dhcpv4_end_ip.s_addr) {
 679                 syslog(LOG_WARNING, "No DHCP range available on %s", iface->name);
 680                 return;
 681         }
 682
 683         int sock = iface->dhcpv4_event.uloop.fd;
 684
 685         struct dhcpv4_message reply = {
 686                 .op = DHCPV4_BOOTREPLY,
 687                 .htype = req->htype,
 688                 .hlen = req->hlen,
 689                 .hops = 0,
 690                 .xid = req->xid,
 691                 .secs = 0,
 692                 .flags = req->flags,
 693                 .ciaddr = {INADDR_ANY},
 694                 .giaddr = req->giaddr,
 695                 .siaddr = iface->dhcpv4_local,
 696         };
 697         memcpy(reply.chaddr, req->chaddr, sizeof(reply.chaddr));
 698
 699         reply.options[0] = 0x63;
 700         reply.options[1] = 0x82;
 701         reply.options[2] = 0x53;
 702         reply.options[3] = 0x63;
 703
 704         uint8_t *cookie = &reply.options[4];
 705         uint8_t reqmsg = DHCPV4_MSG_REQUEST;
 706         uint8_t msg = DHCPV4_MSG_ACK;
 707
 708         uint32_t reqaddr = INADDR_ANY;
 709         uint32_t leasetime = 0;
 710         size_t hostname_len = 0;
 711         char hostname[256];
 712         bool accept_fr_nonce = false;
 713         bool incl_fr_opt = false;
 714
 715         uint8_t *start = &req->options[4];
 716         uint8_t *end = ((uint8_t*)data) + len;
 717         struct dhcpv4_option *opt;
 718         dhcpv4_for_each_option(start, end, opt) {
 719                 if (opt->type == DHCPV4_OPT_MESSAGE && opt->len == 1)
 720                         reqmsg = opt->data[0];
 721                 else if (opt->type == DHCPV4_OPT_HOSTNAME && opt->len > 0) {
 722                         hostname_len = opt->len;
 723                         memcpy(hostname, opt->data, hostname_len);
 724                         hostname[hostname_len] = 0;
 725                 } else if (opt->type == DHCPV4_OPT_IPADDRESS && opt->len == 4)
 726                         memcpy(&reqaddr, opt->data, 4);
 727                 else if (opt->type == DHCPV4_OPT_SERVERID && opt->len == 4) {
 728                         if (memcmp(opt->data, &iface->dhcpv4_local, 4))
 729                                 return;
 730                 } else if (iface->filter_class && opt->type == DHCPV4_OPT_USER_CLASS) {
 731                         uint8_t *c = opt->data, *cend = &opt->data[opt->len];
 732                         for (; c < cend && &c[*c] < cend; c = &c[1 + *c]) {
 733                                 size_t elen = strlen(iface->filter_class);
 734                                 if (*c == elen && !memcmp(&c[1], iface->filter_class, elen))
 735                                         return; // Ignore from homenet
 736                         }
 737                 } else if (opt->type == DHCPV4_OPT_LEASETIME && opt->len == 4)
 738                         memcpy(&leasetime, opt->data, 4);
 739                 else if (opt->type == DHCPV4_OPT_FORCERENEW_NONCE_CAPABLE && opt->len > 0) {
 740                         for (uint8_t i = 0; i < opt->len; i++) {
 741                                 if (opt->data[i] == 1) {
 742                                         accept_fr_nonce = true;
 743                                         break;
 744                                 }
 745                         }
 746
 747                 }
 748         }
 749
 750         if (reqmsg != DHCPV4_MSG_DISCOVER && reqmsg != DHCPV4_MSG_REQUEST &&
 751                         reqmsg != DHCPV4_MSG_INFORM && reqmsg != DHCPV4_MSG_DECLINE &&
 752                         reqmsg != DHCPV4_MSG_RELEASE)
 753                 return;
 754
 755         struct dhcpv4_assignment *lease = NULL;
 756         uint32_t serverid = iface->dhcpv4_local.s_addr;
 757         uint32_t fr_serverid = INADDR_ANY;
 758
 759         if (reqmsg != DHCPV4_MSG_INFORM)
 760                 lease = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr,
 761                                         &leasetime, hostname, hostname_len,
 762                                         accept_fr_nonce, &incl_fr_opt, &fr_serverid);
 763
 764         if (!lease) {
 765                 if (reqmsg == DHCPV4_MSG_REQUEST)
 766                         msg = DHCPV4_MSG_NAK;
 767                 else if (reqmsg == DHCPV4_MSG_DISCOVER)
 768                         return;
 769         } else if (reqmsg == DHCPV4_MSG_DISCOVER)
 770                 msg = DHCPV4_MSG_OFFER;
 771         else if (reqmsg == DHCPV4_MSG_REQUEST &&
 772                         ((reqaddr && reqaddr != lease->addr) ||
 773                          (req->ciaddr.s_addr && req->ciaddr.s_addr != lease->addr))) {
 774                 msg = DHCPV4_MSG_NAK;
 775                 /*
 776                  * DHCP client requested an IP which we can't offer to him. Probably the
 777                  * client changed the network or the network has been changed. The reply
 778                  * type is set to DHCPV4_MSG_NAK, because the client should not use that IP.
 779                  *
 780                  * For modern devices we build an answer that includes a valid IP, like
 781                  * a DHCPV4_MSG_ACK. The client will use that IP and doesn't need to
 782                  * perform additional DHCP round trips.
 783                  *
 784                  */
 785
 786                 /*
 787                  *
 788                  * Buggy clients do serverid checking in nack messages; therefore set the
 789                  * serverid in nack messages triggered by a previous force renew equal to
 790                  * the server id in use at that time by the server
 791                  *
 792                  */
 793                 if (fr_serverid)
 794                         serverid = fr_serverid;
 795
 796                 if (req->ciaddr.s_addr &&
 797                                 ((iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr) !=
 798                                  (req->ciaddr.s_addr & iface->dhcpv4_mask.s_addr)))
 799                         req->ciaddr.s_addr = INADDR_ANY;
 800         }
 801
 802         syslog(LOG_WARNING, "Received %s from %s on %s", dhcpv4_msg_to_string(reqmsg),
 803                         odhcpd_print_mac(req->chaddr, req->hlen), iface->name);
 804
 805 #ifdef WITH_UBUS
 806         if (reqmsg == DHCPV4_MSG_RELEASE)
 807                 ubus_bcast_dhcp_event("dhcp.release", req->chaddr, req->hlen,
 808                                         &req->ciaddr, hostname, iface->ifname);
 809 #endif
 810         if (reqmsg == DHCPV4_MSG_DECLINE || reqmsg == DHCPV4_MSG_RELEASE)
 811                 return;
 812
 813         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg);
 814         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SERVERID, 4, &serverid);
 815
 816         if (lease) {
 817                 uint32_t val;
 818
 819                 reply.yiaddr.s_addr = lease->addr;
 820
 821                 val = htonl(leasetime);
 822                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_LEASETIME, 4, &val);
 823
 824                 if (leasetime != UINT32_MAX) {
 825                         val = htonl(500 * leasetime / 1000);
 826                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_RENEW, 4, &val);
 827
 828                         val = htonl(875 * leasetime / 1000);
 829                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_REBIND, 4, &val);
 830                 }
 831
 832                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_NETMASK, 4,
 833                                 &iface->dhcpv4_mask.s_addr);
 834
 835                 if (lease->hostname)
 836                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_HOSTNAME,
 837                                         strlen(lease->hostname), lease->hostname);
 838
 839                 if (iface->dhcpv4_bcast.s_addr != INADDR_ANY)
 840                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_BROADCAST, 4, &iface->dhcpv4_bcast);
 841
 842                 if (incl_fr_opt) {
 843                         if (reqmsg == DHCPV4_MSG_REQUEST) {
 844                                 struct dhcpv4_auth_forcerenew auth = {
 845                                         .protocol = 3,
 846                                         .algorithm = 1,
 847                                         .rdm = 0,
 848                                         .replay = {htonl(time(NULL)), htonl(++serial)},
 849                                         .type = 1,
 850                                         .key = {0},
 851                                 };
 852
 853                                 memcpy(auth.key, lease->key, sizeof(auth.key));
 854                                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_AUTHENTICATION, sizeof(auth), &auth);
 855                         } else {
 856                                 uint8_t one = 1;
 857                                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_FORCERENEW_NONCE_CAPABLE,
 858                                         sizeof(one), &one);
 859                         }
 860                 }
 861         }
 862
 863         struct ifreq ifr;
 864
 865         memset(&ifr, 0, sizeof(ifr));
 866         strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name) - 1);
 867
 868         if (!ioctl(sock, SIOCGIFMTU, &ifr)) {
 869                 uint16_t mtu = htons(ifr.ifr_mtu);
 870                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MTU, 2, &mtu);
 871         }
 872
 873         if (iface->search && iface->search_len <= 255)
 874                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SEARCH_DOMAIN,
 875                                 iface->search_len, iface->search);
 876         else if (!res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
 877                 uint8_t search_buf[256];
 878                 int len = dn_comp(_res.dnsrch[0], search_buf,
 879                                                 sizeof(search_buf), NULL, NULL);
 880                 if (len > 0)
 881                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SEARCH_DOMAIN,
 882                                         len, search_buf);
 883         }
 884
 885         if (iface->dhcpv4_router_cnt == 0)
 886                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &iface->dhcpv4_local);
 887         else
 888                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER,
 889                                 4 * iface->dhcpv4_router_cnt, iface->dhcpv4_router);
 890
 891
 892         if (iface->dhcpv4_dns_cnt == 0)
 893                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER, 4, &iface->dhcpv4_local);
 894         else
 895                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER,
 896                                 4 * iface->dhcpv4_dns_cnt, iface->dhcpv4_dns);
 897
 898
 899         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_END, 0, NULL);
 900
 901         struct sockaddr_in dest = *((struct sockaddr_in*)addr);
 902         if (req->giaddr.s_addr) {
 903                 /*
 904                  * relay agent is configured, send reply to the agent
 905                  */
 906                 dest.sin_addr = req->giaddr;
 907                 dest.sin_port = htons(DHCPV4_SERVER_PORT);
 908         } else if (req->ciaddr.s_addr && req->ciaddr.s_addr != dest.sin_addr.s_addr) {
 909                 /*
 910                  * client has existing configuration (ciaddr is set) AND this address is
 911                  * not the address it used for the dhcp message
 912                  */
 913                 dest.sin_addr = req->ciaddr;
 914                 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 915         } else if ((ntohs(req->flags) & DHCPV4_FLAG_BROADCAST) ||
 916                         req->hlen != reply.hlen || !reply.yiaddr.s_addr) {
 917                 /*
 918                  * client requests a broadcast reply OR we can't offer an IP
 919                  */
 920                 dest.sin_addr.s_addr = INADDR_BROADCAST;
 921                 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 922         } else if (!req->ciaddr.s_addr && msg == DHCPV4_MSG_NAK) {
 923                 /*
 924                  * client has no previous configuration -> no IP, so we need to reply
 925                  * with a broadcast packet
 926                  */
 927                 dest.sin_addr.s_addr = INADDR_BROADCAST;
 928                 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 929         } else {
 930                 struct arpreq arp = {.arp_flags = ATF_COM};
 931
 932                 /*
 933                  * send reply to the newly (in this proccess) allocated IP
 934                  */
 935                 dest.sin_addr = reply.yiaddr;
 936                 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 937
 938                 memcpy(arp.arp_ha.sa_data, req->chaddr, 6);
 939                 memcpy(&arp.arp_pa, &dest, sizeof(arp.arp_pa));
 940                 memcpy(arp.arp_dev, iface->ifname, sizeof(arp.arp_dev));
 941
 942                 if (ioctl(sock, SIOCSARP, &arp) < 0)
 943                         syslog(LOG_ERR, "ioctl(SIOCSARP): %m");
 944         }
 945
 946         if (sendto(sock, &reply, sizeof(reply), MSG_DONTWAIT,
 947                         (struct sockaddr*)&dest, sizeof(dest)) < 0)
 948                 syslog(LOG_ERR, "Failed to send %s to %s - %s: %m",
 949                         dhcpv4_msg_to_string(msg),
 950                         dest.sin_addr.s_addr == INADDR_BROADCAST ?
 951                         "ff:ff:ff:ff:ff:ff": odhcpd_print_mac(req->chaddr, req->hlen),
 952                         inet_ntoa(dest.sin_addr));
 953         else
 954                 syslog(LOG_ERR, "Sent %s to %s - %s",
 955                         dhcpv4_msg_to_string(msg),
 956                         dest.sin_addr.s_addr == INADDR_BROADCAST ?
 957                         "ff:ff:ff:ff:ff:ff": odhcpd_print_mac(req->chaddr, req->hlen),
 958                         inet_ntoa(dest.sin_addr));
 959
 960
 961 #ifdef WITH_UBUS
 962         if (msg == DHCPV4_MSG_ACK)
 963                 ubus_bcast_dhcp_event("dhcp.ack", req->chaddr, req->hlen, &reply.yiaddr,
 964                                         hostname, iface->ifname);
 965 #endif
 966 }
 967
 968 static bool dhcpv4_assign(struct interface *iface,
 969                 struct dhcpv4_assignment *assign, uint32_t raddr)
 970 {
 971         uint32_t start = ntohl(iface->dhcpv4_start_ip.s_addr);
 972         uint32_t end = ntohl(iface->dhcpv4_end_ip.s_addr);
 973         uint32_t count = end - start + 1;
 974
 975         /* try to assign the IP the client asked for */
 976         if (start <= ntohl(raddr) && ntohl(raddr) <= end &&
 977                         !find_assignment_by_addr(iface, raddr)) {
 978                 assign->addr = raddr;
 979                 syslog(LOG_INFO, "Assigning the IP the client asked for: %u.%u.%u.%u",
 980                                 ((uint8_t *)&assign->addr)[0],
 981                                 ((uint8_t *)&assign->addr)[1],
 982                                 ((uint8_t *)&assign->addr)[2],
 983                                 ((uint8_t *)&assign->addr)[3]);
 984                 return true;
 985         }
 986
 987         /* Seed RNG with checksum of hwaddress */
 988         uint32_t seed = 0;
 989         for (size_t i = 0; i < sizeof(assign->hwaddr); ++i) {
 990                 /* Knuth's multiplicative method */
 991                 uint8_t o = assign->hwaddr[i];
 992                 seed += (o*2654435761) % UINT32_MAX;
 993         }
 994
 995         srand(seed);
 996
 997         uint32_t try = (((uint32_t)rand()) % count) + start;
 998
 999         if (list_empty(&iface->dhcpv4_assignments)) {
1000                 assign->addr = htonl(try);
1001                 syslog(LOG_INFO, "Assigning mapped IP (empty list): %u.%u.%u.%u",
1002                                 ((uint8_t *)&assign->addr)[0],
1003                                 ((uint8_t *)&assign->addr)[1],
1004                                 ((uint8_t *)&assign->addr)[2],
1005                                 ((uint8_t *)&assign->addr)[3]);
1006                 return true;
1007         }
1008
1009         for (uint32_t i = 0; i < count; ++i) {
1010                 if (!find_assignment_by_addr(iface, htonl(try))) {
1011                         /* test was successful: IP address is not assigned, assign it */
1012                         assign->addr = htonl(try);
1013                         syslog(LOG_DEBUG, "Assigning mapped IP: %u.%u.%u.%u (try %u of %u)",
1014                                         ((uint8_t *)&assign->addr)[0],
1015                                         ((uint8_t *)&assign->addr)[1],
1016                                         ((uint8_t *)&assign->addr)[2],
1017                                         ((uint8_t *)&assign->addr)[3],
1018                                         i, count);
1019                         return true;
1020                 }
1021                 try = (((try - start) + 1) % count) + start;
1022         }
1023
1024         syslog(LOG_WARNING, "Can't assign any IP address -> address space is full");
1025         return false;
1026 }
1027
1028
1029 static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
1030                 enum dhcpv4_msg msg, const uint8_t *mac, const uint32_t reqaddr,
1031                 uint32_t *leasetime, const char *hostname, const size_t hostname_len,
1032                 const bool accept_fr_nonce, bool *incl_fr_opt, uint32_t *fr_serverid)
1033 {
1034         struct dhcpv4_assignment *a = find_assignment_by_hwaddr(iface, mac);
1035         struct dhcpv4_assignment *lease = NULL;
1036         time_t now = odhcpd_time();
1037
1038         if (a && (a->flags & OAF_BOUND) && a->fr_ip) {
1039                 *fr_serverid = a->fr_ip->addr.addr.in.s_addr;
1040                 dhcpv4_fr_stop(a);
1041         }
1042
1043         if (msg == DHCPV4_MSG_DISCOVER || msg == DHCPV4_MSG_REQUEST) {
1044                 bool assigned = !!a;
1045
1046                 if (!a) {
1047                         if (!iface->no_dynamic_dhcp) {
1048                                 /* Create new binding */
1049                                 a = calloc(1, sizeof(*a));
1050                                 if (!a) {
1051                                         syslog(LOG_ERR, "Failed to calloc binding on interface %s",
1052                                                         iface->ifname);
1053                                         return NULL;
1054                                 }
1055                                 memcpy(a->hwaddr, mac, sizeof(a->hwaddr));
1056                                 /* Don't consider new assignment as infinite */
1057                                 a->valid_until = now;
1058
1059                                 assigned = dhcpv4_assign(iface, a, reqaddr);
1060                                 if (assigned) {
1061                                         a->iface = iface;
1062                                         list_add(&a->head, &iface->dhcpv4_assignments);
1063                                 }
1064                         }
1065                 } else if ((a->addr & iface->dhcpv4_mask.s_addr) !=
1066                                 (iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr)) {
1067                         list_del(&a->head);
1068
1069                         assigned = dhcpv4_assign(iface, a, reqaddr);
1070                         if (assigned)
1071                                 list_add(&a->head, &iface->dhcpv4_assignments);
1072                 }
1073
1074                 if (assigned) {
1075                         uint32_t my_leasetime;
1076
1077                         if (a->leasetime)
1078                                 my_leasetime = a->leasetime;
1079                         else
1080                                 my_leasetime = iface->dhcpv4_leasetime;
1081
1082                         if ((*leasetime == 0) || (my_leasetime < *leasetime))
1083                                 *leasetime = my_leasetime;
1084
1085                         if (msg == DHCPV4_MSG_DISCOVER) {
1086                                 a->flags &= ~OAF_BOUND;
1087
1088                                 *incl_fr_opt = accept_fr_nonce;
1089                                 if (!(a->flags & OAF_STATIC))
1090                                         a->valid_until = now;
1091                         } else {
1092                                 if (hostname_len > 0) {
1093                                         a->hostname = realloc(a->hostname, hostname_len + 1);
1094                                         if (a->hostname) {
1095                                                 memcpy(a->hostname, hostname, hostname_len);
1096                                                 a->hostname[hostname_len] = 0;
1097
1098                                                 if (odhcpd_valid_hostname(a->hostname))
1099                                                         a->flags &= ~OAF_BROKEN_HOSTNAME;
1100                                                 else
1101                                                         a->flags |= OAF_BROKEN_HOSTNAME;
1102                                         }
1103                                 }
1104
1105                                 if (!(a->flags & OAF_BOUND)) {
1106                                         a->accept_fr_nonce = accept_fr_nonce;
1107                                         *incl_fr_opt = accept_fr_nonce;
1108                                         odhcpd_urandom(a->key, sizeof(a->key));
1109                                         a->flags |= OAF_BOUND;
1110                                 } else
1111                                         *incl_fr_opt = false;
1112
1113                                 if (!(a->flags & OAF_STATIC))
1114                                         a->valid_until = ((*leasetime == UINT32_MAX) ? 0 : (time_t)(now + *leasetime));
1115                         }
1116                 } else if (!assigned && a) {
1117                         /* Cleanup failed assignment */
1118                         free_dhcpv4_assignment(a);
1119                         a = NULL;
1120                 }
1121
1122                 if (assigned && a)
1123                         lease = a;
1124         } else if (msg == DHCPV4_MSG_RELEASE && a) {
1125                 a->flags &= ~OAF_BOUND;
1126
1127                 if (!(a->flags & OAF_STATIC))
1128                         a->valid_until = now - 1;
1129
1130         } else if (msg == DHCPV4_MSG_DECLINE && a) {
1131                 a->flags &= ~OAF_BOUND;
1132
1133                 if (!(a->flags & OAF_STATIC)) {
1134                         memset(a->hwaddr, 0, sizeof(a->hwaddr));
1135                         a->valid_until = now + 3600; /* Block address for 1h */
1136                 }
1137         }
1138
1139         dhcpv6_write_statefile();
1140
1141         return lease;
1142 }