src/network/networkd-dhcp4.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <netinet/in.h>
   4 #include <linux/if.h>
   5
   6 #include "alloc-util.h"
   7 #include "hostname-util.h"
   8 #include "parse-util.h"
   9 #include "network-internal.h"
  10 #include "networkd-link.h"
  11 #include "networkd-manager.h"
  12 #include "networkd-network.h"
  13 #include "string-util.h"
  14 #include "sysctl-util.h"
  15
  16 static int dhcp4_route_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
  17         int r;
  18
  19         assert(link);
  20         assert(link->dhcp4_messages > 0);
  21
  22         link->dhcp4_messages--;
  23
  24         r = sd_netlink_message_get_errno(m);
  25         if (r < 0 && r != -EEXIST) {
  26                 log_link_error_errno(link, r, "Could not set DHCPv4 route: %m");
  27                 link_enter_failed(link);
  28         }
  29
  30         if (link->dhcp4_messages == 0) {
  31                 link->dhcp4_configured = true;
  32                 link_check_ready(link);
  33         }
  34
  35         return 1;
  36 }
  37
  38 static int route_scope_from_address(const Route *route, const struct in_addr *self_addr) {
  39         assert(route);
  40         assert(self_addr);
  41
  42         if (in_addr_is_localhost(AF_INET, &route->dst) ||
  43             (self_addr->s_addr && route->dst.in.s_addr == self_addr->s_addr))
  44                 return RT_SCOPE_HOST;
  45         else if (in4_addr_is_null(&route->gw.in))
  46                 return RT_SCOPE_LINK;
  47         else
  48                 return RT_SCOPE_UNIVERSE;
  49 }
  50
  51 static int link_set_dhcp_routes(Link *link) {
  52         _cleanup_free_ sd_dhcp_route **static_routes = NULL;
  53         bool classless_route = false, static_route = false;
  54         const struct in_addr *router;
  55         struct in_addr address;
  56         int r, n, i;
  57         uint32_t table;
  58
  59         assert(link);
  60
  61         if (!link->dhcp_lease) /* link went down while we configured the IP addresses? */
  62                 return 0;
  63
  64         if (!link->network) /* link went down while we configured the IP addresses? */
  65                 return 0;
  66
  67         if (!link->network->dhcp_use_routes)
  68                 return 0;
  69
  70         table = link_get_dhcp_route_table(link);
  71
  72         r = sd_dhcp_lease_get_address(link->dhcp_lease, &address);
  73         if (r < 0)
  74                 return log_link_warning_errno(link, r, "DHCP error: could not get address: %m");
  75
  76         n = sd_dhcp_lease_get_routes(link->dhcp_lease, &static_routes);
  77         if (n == -ENODATA)
  78                 log_link_debug_errno(link, n, "DHCP: No routes received from DHCP server: %m");
  79         else if (n < 0)
  80                 log_link_debug_errno(link, n, "DHCP error: could not get routes: %m");
  81
  82         for (i = 0; i < n; i++) {
  83                 switch (sd_dhcp_route_get_option(static_routes[i])) {
  84                 case SD_DHCP_OPTION_CLASSLESS_STATIC_ROUTE:
  85                         classless_route = true;
  86                         break;
  87                 case SD_DHCP_OPTION_STATIC_ROUTE:
  88                         static_route = true;
  89                         break;
  90                 }
  91         }
  92
  93         for (i = 0; i < n; i++) {
  94                 _cleanup_(route_freep) Route *route = NULL;
  95
  96                 /* if the DHCP server returns both a Classless Static Routes option and a Static Routes option,
  97                    the DHCP client MUST ignore the Static Routes option. */
  98                 if (classless_route &&
  99                     sd_dhcp_route_get_option(static_routes[i]) != SD_DHCP_OPTION_CLASSLESS_STATIC_ROUTE)
 100                         continue;
 101
 102                 r = route_new(&route);
 103                 if (r < 0)
 104                         return log_link_error_errno(link, r, "Could not allocate route: %m");
 105
 106                 route->family = AF_INET;
 107                 route->protocol = RTPROT_DHCP;
 108                 assert_se(sd_dhcp_route_get_gateway(static_routes[i], &route->gw.in) >= 0);
 109                 assert_se(sd_dhcp_route_get_destination(static_routes[i], &route->dst.in) >= 0);
 110                 assert_se(sd_dhcp_route_get_destination_prefix_length(static_routes[i], &route->dst_prefixlen) >= 0);
 111                 route->priority = link->network->dhcp_route_metric;
 112                 route->table = table;
 113                 route->scope = route_scope_from_address(route, &address);
 114
 115                 r = route_configure(route, link, dhcp4_route_handler);
 116                 if (r < 0)
 117                         return log_link_warning_errno(link, r, "Could not set host route: %m");
 118
 119                 link->dhcp4_messages++;
 120         }
 121
 122         r = sd_dhcp_lease_get_router(link->dhcp_lease, &router);
 123         if (IN_SET(r, 0, -ENODATA))
 124                 log_link_info(link, "DHCP: No gateway received from DHCP server.");
 125         else if (r < 0)
 126                 log_link_warning_errno(link, r, "DHCP error: could not get gateway: %m");
 127         else if (in4_addr_is_null(&router[0]))
 128                 log_link_info(link, "DHCP: Received gateway is null.");
 129
 130         /* According to RFC 3442: If the DHCP server returns both a Classless Static Routes option and
 131            a Router option, the DHCP client MUST ignore the Router option. */
 132         if (classless_route && static_route)
 133                 log_link_warning(link, "Classless static routes received from DHCP server: ignoring static-route option and router option");
 134
 135         if (r > 0 && !classless_route && !in4_addr_is_null(&router[0])) {
 136                 _cleanup_(route_freep) Route *route = NULL, *route_gw = NULL;
 137
 138                 r = route_new(&route_gw);
 139                 if (r < 0)
 140                         return log_link_error_errno(link, r,  "Could not allocate route: %m");
 141
 142                 /* The dhcp netmask may mask out the gateway. Add an explicit
 143                  * route for the gw host so that we can route no matter the
 144                  * netmask or existing kernel route tables. */
 145                 route_gw->family = AF_INET;
 146                 route_gw->dst.in = router[0];
 147                 route_gw->dst_prefixlen = 32;
 148                 route_gw->prefsrc.in = address;
 149                 route_gw->scope = RT_SCOPE_LINK;
 150                 route_gw->protocol = RTPROT_DHCP;
 151                 route_gw->priority = link->network->dhcp_route_metric;
 152                 route_gw->table = table;
 153
 154                 r = route_configure(route_gw, link, dhcp4_route_handler);
 155                 if (r < 0)
 156                         return log_link_warning_errno(link, r, "Could not set host route: %m");
 157
 158                 link->dhcp4_messages++;
 159
 160                 r = route_new(&route);
 161                 if (r < 0)
 162                         return log_link_error_errno(link, r, "Could not allocate route: %m");
 163
 164                 route->family = AF_INET;
 165                 route->gw.in = router[0];
 166                 route->prefsrc.in = address;
 167                 route->protocol = RTPROT_DHCP;
 168                 route->priority = link->network->dhcp_route_metric;
 169                 route->table = table;
 170
 171                 r = route_configure(route, link, dhcp4_route_handler);
 172                 if (r < 0) {
 173                         log_link_warning_errno(link, r, "Could not set routes: %m");
 174                         link_enter_failed(link);
 175                         return r;
 176                 }
 177
 178                 link->dhcp4_messages++;
 179         }
 180
 181         return 0;
 182 }
 183
 184 static int dhcp_remove_routes(Link *link, struct in_addr *address) {
 185         _cleanup_free_ sd_dhcp_route **routes = NULL;
 186         uint32_t table;
 187         int n, i, r;
 188
 189         assert(link);
 190         assert(address);
 191
 192         if (!link->network->dhcp_use_routes)
 193                 return 0;
 194
 195         n = sd_dhcp_lease_get_routes(link->dhcp_lease, &routes);
 196         if (IN_SET(n, 0, -ENODATA)) {
 197                 log_link_debug(link, "DHCP: No routes received from DHCP server: %m");
 198                 return 0;
 199         } else if (n < 0)
 200                 return log_link_error_errno(link, n, "DHCP error: could not get routes: %m");
 201
 202         table = link_get_dhcp_route_table(link);
 203
 204         for (i = 0; i < n; i++) {
 205                 _cleanup_(route_freep) Route *route = NULL;
 206
 207                 r = route_new(&route);
 208                 if (r < 0)
 209                         return log_oom();
 210
 211                 route->family = AF_INET;
 212                 assert_se(sd_dhcp_route_get_gateway(routes[i], &route->gw.in) >= 0);
 213                 assert_se(sd_dhcp_route_get_destination(routes[i], &route->dst.in) >= 0);
 214                 assert_se(sd_dhcp_route_get_destination_prefix_length(routes[i], &route->dst_prefixlen) >= 0);
 215                 route->priority = link->network->dhcp_route_metric;
 216                 route->table = table;
 217                 route->scope = route_scope_from_address(route, address);
 218
 219                 (void) route_remove(route, link, NULL);
 220         }
 221
 222         return n;
 223 }
 224
 225 static int dhcp_remove_router(Link *link, struct in_addr *address) {
 226         _cleanup_(route_freep) Route *route_gw = NULL, *route = NULL;
 227         const struct in_addr *router;
 228         uint32_t table;
 229         int r;
 230
 231         assert(link);
 232         assert(address);
 233
 234         if (!link->network->dhcp_use_routes)
 235                 return 0;
 236
 237         r = sd_dhcp_lease_get_router(link->dhcp_lease, &router);
 238         if (IN_SET(r, 0, -ENODATA)) {
 239                 log_link_debug(link, "DHCP: No gateway received from DHCP server.");
 240                 return 0;
 241         } else if (r < 0)
 242                 return log_link_error_errno(link, r, "DHCP error: could not get gateway: %m");
 243         else if (in4_addr_is_null(&router[0])) {
 244                 log_link_info(link, "DHCP: Received gateway is null, ignoring.");
 245                 return 0;
 246         }
 247
 248         table = link_get_dhcp_route_table(link);
 249
 250         r = route_new(&route_gw);
 251         if (r < 0)
 252                 return log_oom();
 253
 254         route_gw->family = AF_INET;
 255         route_gw->dst.in = router[0];
 256         route_gw->dst_prefixlen = 32;
 257         route_gw->prefsrc.in = *address;
 258         route_gw->scope = RT_SCOPE_LINK;
 259         route_gw->protocol = RTPROT_DHCP;
 260         route_gw->priority = link->network->dhcp_route_metric;
 261         route_gw->table = table;
 262
 263         (void) route_remove(route_gw, link, NULL);
 264
 265         r = route_new(&route);
 266         if (r < 0)
 267                 return log_oom();
 268
 269         route->family = AF_INET;
 270         route->gw.in = router[0];
 271         route->prefsrc.in = *address;
 272         route->protocol = RTPROT_DHCP;
 273         route->priority = link->network->dhcp_route_metric;
 274         route->table = table;
 275
 276         (void) route_remove(route, link, NULL);
 277
 278         return 0;
 279 }
 280
 281 static int dhcp_remove_address(Link *link, struct in_addr *address) {
 282         _cleanup_(address_freep) Address *a = NULL;
 283         struct in_addr netmask;
 284         int r;
 285
 286         assert(link);
 287         assert(address);
 288
 289         if (in4_addr_is_null(address))
 290                 return 0;
 291
 292         r = address_new(&a);
 293         if (r < 0)
 294                 return log_oom();
 295
 296         a->family = AF_INET;
 297         a->in_addr.in = *address;
 298
 299         if (sd_dhcp_lease_get_netmask(link->dhcp_lease, &netmask) >= 0)
 300                 a->prefixlen = in4_addr_netmask_to_prefixlen(&netmask);
 301
 302         (void) address_remove(a, link, NULL);
 303
 304         return 0;
 305 }
 306
 307 static int dhcp_reset_mtu(Link *link) {
 308         uint16_t mtu;
 309         int r;
 310
 311         assert(link);
 312
 313         if (!link->network->dhcp_use_mtu)
 314                 return 0;
 315
 316         r = sd_dhcp_lease_get_mtu(link->dhcp_lease, &mtu);
 317         if (r < 0)
 318                 return r;
 319
 320         if (link->original_mtu == mtu)
 321                 return 0;
 322
 323         r = link_set_mtu(link, link->original_mtu);
 324         if (r < 0) {
 325                 log_link_error_errno(link, r, "DHCP error: could not reset MTU: %m");
 326                 link_enter_failed(link);
 327                 return r;
 328         }
 329
 330         return 0;
 331 }
 332
 333 static int dhcp_reset_hostname(Link *link) {
 334         const char *hostname;
 335         int r;
 336
 337         assert(link);
 338
 339         if (!link->network->dhcp_use_hostname)
 340                 return 0;
 341
 342         hostname = link->network->dhcp_hostname;
 343         if (!hostname)
 344                 (void) sd_dhcp_lease_get_hostname(link->dhcp_lease, &hostname);
 345
 346         if (!hostname)
 347                 return 0;
 348
 349         /* If a hostname was set due to the lease, then unset it now. */
 350         r = manager_set_hostname(link->manager, NULL);
 351         if (r < 0)
 352                 return log_link_error_errno(link, r, "DHCP error: Failed to reset transient hostname: %m");
 353
 354         return 0;
 355 }
 356
 357 static int dhcp_lease_lost(Link *link) {
 358         struct in_addr address = {};
 359
 360         assert(link);
 361         assert(link->dhcp_lease);
 362
 363         log_link_warning(link, "DHCP lease lost");
 364
 365         link->dhcp4_configured = false;
 366
 367         (void) sd_dhcp_lease_get_address(link->dhcp_lease, &address);
 368         (void) dhcp_remove_routes(link, &address);
 369         (void) dhcp_remove_router(link, &address);
 370         (void) dhcp_remove_address(link, &address);
 371         (void) dhcp_reset_mtu(link);
 372         (void) dhcp_reset_hostname(link);
 373
 374         link->dhcp_lease = sd_dhcp_lease_unref(link->dhcp_lease);
 375         link_dirty(link);
 376
 377         return 0;
 378 }
 379
 380 static int dhcp4_address_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
 381         int r;
 382
 383         assert(link);
 384
 385         r = sd_netlink_message_get_errno(m);
 386         if (r < 0 && r != -EEXIST) {
 387                 log_link_error_errno(link, r, "Could not set DHCPv4 address: %m");
 388                 link_enter_failed(link);
 389         } else if (r >= 0)
 390                 manager_rtnl_process_address(rtnl, m, link->manager);
 391
 392         link_set_dhcp_routes(link);
 393
 394         /* Add back static routes since kernel removes while DHCPv4 address is removed from when lease expires */
 395         link_request_set_routes(link);
 396
 397         if (link->dhcp4_messages == 0) {
 398                 link->dhcp4_configured = true;
 399                 link_check_ready(link);
 400         }
 401
 402         return 1;
 403 }
 404
 405 static int dhcp4_update_address(Link *link,
 406                                 struct in_addr *address,
 407                                 struct in_addr *netmask,
 408                                 uint32_t lifetime) {
 409         _cleanup_(address_freep) Address *addr = NULL;
 410         unsigned prefixlen;
 411         int r;
 412
 413         assert(address);
 414         assert(netmask);
 415         assert(lifetime);
 416
 417         prefixlen = in4_addr_netmask_to_prefixlen(netmask);
 418
 419         r = address_new(&addr);
 420         if (r < 0)
 421                 return r;
 422
 423         addr->family = AF_INET;
 424         addr->in_addr.in.s_addr = address->s_addr;
 425         addr->cinfo.ifa_prefered = lifetime;
 426         addr->cinfo.ifa_valid = lifetime;
 427         addr->prefixlen = prefixlen;
 428         addr->broadcast.s_addr = address->s_addr | ~netmask->s_addr;
 429
 430         /* allow reusing an existing address and simply update its lifetime
 431          * in case it already exists */
 432         r = address_configure(addr, link, dhcp4_address_handler, true);
 433         if (r < 0)
 434                 return r;
 435
 436         return 0;
 437 }
 438
 439 static int dhcp_lease_renew(sd_dhcp_client *client, Link *link) {
 440         sd_dhcp_lease *lease;
 441         struct in_addr address;
 442         struct in_addr netmask;
 443         uint32_t lifetime = CACHE_INFO_INFINITY_LIFE_TIME;
 444         int r;
 445
 446         assert(link);
 447         assert(client);
 448         assert(link->network);
 449
 450         r = sd_dhcp_client_get_lease(client, &lease);
 451         if (r < 0)
 452                 return log_link_warning_errno(link, r, "DHCP error: no lease: %m");
 453
 454         sd_dhcp_lease_unref(link->dhcp_lease);
 455         link->dhcp4_configured = false;
 456         link->dhcp_lease = sd_dhcp_lease_ref(lease);
 457         link_dirty(link);
 458
 459         r = sd_dhcp_lease_get_address(lease, &address);
 460         if (r < 0)
 461                 return log_link_warning_errno(link, r, "DHCP error: no address: %m");
 462
 463         r = sd_dhcp_lease_get_netmask(lease, &netmask);
 464         if (r < 0)
 465                 return log_link_warning_errno(link, r, "DHCP error: no netmask: %m");
 466
 467         if (!link->network->dhcp_critical) {
 468                 r = sd_dhcp_lease_get_lifetime(link->dhcp_lease, &lifetime);
 469                 if (r < 0)
 470                         return log_link_warning_errno(link, r, "DHCP error: no lifetime: %m");
 471         }
 472
 473         r = dhcp4_update_address(link, &address, &netmask, lifetime);
 474         if (r < 0) {
 475                 log_link_warning_errno(link, r, "Could not update IP address: %m");
 476                 link_enter_failed(link);
 477                 return r;
 478         }
 479
 480         return 0;
 481 }
 482
 483 static int dhcp_lease_acquired(sd_dhcp_client *client, Link *link) {
 484         const struct in_addr *router;
 485         sd_dhcp_lease *lease;
 486         struct in_addr address;
 487         struct in_addr netmask;
 488         unsigned prefixlen;
 489         uint32_t lifetime = CACHE_INFO_INFINITY_LIFE_TIME;
 490         int r;
 491
 492         assert(client);
 493         assert(link);
 494
 495         link->dhcp4_configured = false;
 496
 497         r = sd_dhcp_client_get_lease(client, &lease);
 498         if (r < 0)
 499                 return log_link_error_errno(link, r, "DHCP error: No lease: %m");
 500
 501         r = sd_dhcp_lease_get_address(lease, &address);
 502         if (r < 0)
 503                 return log_link_error_errno(link, r, "DHCP error: No address: %m");
 504
 505         r = sd_dhcp_lease_get_netmask(lease, &netmask);
 506         if (r < 0)
 507                 return log_link_error_errno(link, r, "DHCP error: No netmask: %m");
 508
 509         prefixlen = in4_addr_netmask_to_prefixlen(&netmask);
 510
 511         r = sd_dhcp_lease_get_router(lease, &router);
 512         if (r < 0 && r != -ENODATA)
 513                 return log_link_error_errno(link, r, "DHCP error: Could not get gateway: %m");
 514
 515         if (r > 0 && !in4_addr_is_null(&router[0]))
 516                 log_struct(LOG_INFO,
 517                            LOG_LINK_INTERFACE(link),
 518                            LOG_LINK_MESSAGE(link, "DHCPv4 address %u.%u.%u.%u/%u via %u.%u.%u.%u",
 519                                             ADDRESS_FMT_VAL(address),
 520                                             prefixlen,
 521                                             ADDRESS_FMT_VAL(router[0])),
 522                            "ADDRESS=%u.%u.%u.%u", ADDRESS_FMT_VAL(address),
 523                            "PREFIXLEN=%u", prefixlen,
 524                            "GATEWAY=%u.%u.%u.%u", ADDRESS_FMT_VAL(router[0]));
 525         else
 526                 log_struct(LOG_INFO,
 527                            LOG_LINK_INTERFACE(link),
 528                            LOG_LINK_MESSAGE(link, "DHCPv4 address %u.%u.%u.%u/%u",
 529                                             ADDRESS_FMT_VAL(address),
 530                                             prefixlen),
 531                            "ADDRESS=%u.%u.%u.%u", ADDRESS_FMT_VAL(address),
 532                            "PREFIXLEN=%u", prefixlen);
 533
 534         link->dhcp_lease = sd_dhcp_lease_ref(lease);
 535         link_dirty(link);
 536
 537         if (link->network->dhcp_use_mtu) {
 538                 uint16_t mtu;
 539
 540                 r = sd_dhcp_lease_get_mtu(lease, &mtu);
 541                 if (r >= 0) {
 542                         r = link_set_mtu(link, mtu);
 543                         if (r < 0)
 544                                 log_link_error_errno(link, r, "Failed to set MTU to %" PRIu16 ": %m", mtu);
 545                 }
 546         }
 547
 548         if (link->network->dhcp_use_hostname) {
 549                 const char *dhcpname = NULL;
 550                 _cleanup_free_ char *hostname = NULL;
 551
 552                 if (link->network->dhcp_hostname)
 553                         dhcpname = link->network->dhcp_hostname;
 554                 else
 555                         (void) sd_dhcp_lease_get_hostname(lease, &dhcpname);
 556
 557                 if (dhcpname) {
 558                         r = shorten_overlong(dhcpname, &hostname);
 559                         if (r < 0)
 560                                 log_link_warning_errno(link, r, "Unable to shorten overlong DHCP hostname '%s', ignoring: %m", dhcpname);
 561                         if (r == 1)
 562                                 log_link_notice(link, "Overlong DHCP hostname received, shortened from '%s' to '%s'", dhcpname, hostname);
 563                 }
 564
 565                 if (hostname) {
 566                         r = manager_set_hostname(link->manager, hostname);
 567                         if (r < 0)
 568                                 log_link_error_errno(link, r, "Failed to set transient hostname to '%s': %m", hostname);
 569                 }
 570         }
 571
 572         if (link->network->dhcp_use_timezone) {
 573                 const char *tz = NULL;
 574
 575                 (void) sd_dhcp_lease_get_timezone(link->dhcp_lease, &tz);
 576
 577                 if (tz) {
 578                         r = manager_set_timezone(link->manager, tz);
 579                         if (r < 0)
 580                                 log_link_error_errno(link, r, "Failed to set timezone to '%s': %m", tz);
 581                 }
 582         }
 583
 584         if (!link->network->dhcp_critical) {
 585                 r = sd_dhcp_lease_get_lifetime(link->dhcp_lease, &lifetime);
 586                 if (r < 0)
 587                         return log_link_warning_errno(link, r, "DHCP error: no lifetime: %m");
 588         }
 589
 590         r = dhcp4_update_address(link, &address, &netmask, lifetime);
 591         if (r < 0) {
 592                 log_link_warning_errno(link, r, "Could not update IP address: %m");
 593                 link_enter_failed(link);
 594                 return r;
 595         }
 596
 597         return 0;
 598 }
 599
 600 static int dhcp_server_is_black_listed(Link *link, sd_dhcp_client *client) {
 601         sd_dhcp_lease *lease;
 602         struct in_addr addr;
 603         int r;
 604
 605         assert(link);
 606         assert(link->network);
 607         assert(client);
 608
 609         r = sd_dhcp_client_get_lease(client, &lease);
 610         if (r < 0)
 611                 return log_link_error_errno(link, r, "Failed to get DHCP lease: %m");
 612
 613         r = sd_dhcp_lease_get_server_identifier(lease, &addr);
 614         if (r < 0)
 615                 return log_link_debug_errno(link, r, "Failed to get DHCP server ip address: %m");
 616
 617         if (set_contains(link->network->dhcp_black_listed_ip, UINT32_TO_PTR(addr.s_addr))) {
 618                 log_struct(LOG_DEBUG,
 619                            LOG_LINK_INTERFACE(link),
 620                            LOG_LINK_MESSAGE(link, "DHCPv4 ip '%u.%u.%u.%u' found in black listed ip addresses, ignoring offer",
 621                                             ADDRESS_FMT_VAL(addr)));
 622                 return true;
 623         }
 624
 625         return false;
 626 }
 627
 628 static int dhcp4_handler(sd_dhcp_client *client, int event, void *userdata) {
 629         Link *link = userdata;
 630         int r;
 631
 632         assert(link);
 633         assert(link->network);
 634         assert(link->manager);
 635
 636         if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
 637                 return 0;
 638
 639         switch (event) {
 640                 case SD_DHCP_CLIENT_EVENT_STOP:
 641
 642                         if (link_ipv4ll_enabled(link, ADDRESS_FAMILY_FALLBACK_IPV4)) {
 643                                 assert(link->ipv4ll);
 644
 645                                 log_link_debug(link, "DHCP client is stopped. Acquiring IPv4 link-local address");
 646
 647                                 r = sd_ipv4ll_start(link->ipv4ll);
 648                                 if (r < 0)
 649                                         return log_link_warning_errno(link, r, "Could not acquire IPv4 link-local address: %m");
 650                         }
 651
 652                         if (link->network->dhcp_critical) {
 653                                 log_link_notice(link, "DHCPv4 connection considered critical, ignoring request to reconfigure it.");
 654                                 return 0;
 655                         }
 656
 657                         if (link->network->dhcp_send_release)
 658                                 (void) sd_dhcp_client_send_release(client);
 659
 660                         if (link->dhcp_lease) {
 661                                 r = dhcp_lease_lost(link);
 662                                 if (r < 0) {
 663                                         link_enter_failed(link);
 664                                         return r;
 665                                 }
 666                         }
 667
 668                         break;
 669                 case SD_DHCP_CLIENT_EVENT_EXPIRED:
 670                 case SD_DHCP_CLIENT_EVENT_IP_CHANGE:
 671
 672                         if (link->network->dhcp_critical) {
 673                                 log_link_notice(link, "DHCPv4 connection considered critical, ignoring request to reconfigure it.");
 674                                 return 0;
 675                         }
 676
 677                         if (link->dhcp_lease) {
 678                                 r = dhcp_lease_lost(link);
 679                                 if (r < 0) {
 680                                         link_enter_failed(link);
 681                                         return r;
 682                                 }
 683                         }
 684
 685                         if (event == SD_DHCP_CLIENT_EVENT_IP_CHANGE) {
 686                                 r = dhcp_lease_acquired(client, link);
 687                                 if (r < 0) {
 688                                         link_enter_failed(link);
 689                                         return r;
 690                                 }
 691                         }
 692
 693                         break;
 694                 case SD_DHCP_CLIENT_EVENT_RENEW:
 695                         r = dhcp_lease_renew(client, link);
 696                         if (r < 0) {
 697                                 link_enter_failed(link);
 698                                 return r;
 699                         }
 700                         break;
 701                 case SD_DHCP_CLIENT_EVENT_IP_ACQUIRE:
 702                         r = dhcp_lease_acquired(client, link);
 703                         if (r < 0) {
 704                                 link_enter_failed(link);
 705                                 return r;
 706                         }
 707                         break;
 708                 case SD_DHCP_CLIENT_EVENT_SELECTING:
 709                         r = dhcp_server_is_black_listed(link, client);
 710                         if (r < 0)
 711                                 return r;
 712                         if (r != 0)
 713                                 return -ENOMSG;
 714                         break;
 715                 default:
 716                         if (event < 0)
 717                                 log_link_warning_errno(link, event, "DHCP error: Client failed: %m");
 718                         else
 719                                 log_link_warning(link, "DHCP unknown event: %i", event);
 720                         break;
 721         }
 722
 723         return 0;
 724 }
 725
 726 static int dhcp4_set_hostname(Link *link) {
 727         _cleanup_free_ char *hostname = NULL;
 728         const char *hn;
 729         int r;
 730
 731         assert(link);
 732
 733         if (!link->network->dhcp_send_hostname)
 734                 hn = NULL;
 735         else if (link->network->dhcp_hostname)
 736                 hn = link->network->dhcp_hostname;
 737         else {
 738                 r = gethostname_strict(&hostname);
 739                 if (r < 0 && r != -ENXIO) /* ENXIO: no hostname set or hostname is "localhost" */
 740                         return r;
 741
 742                 hn = hostname;
 743         }
 744
 745         r = sd_dhcp_client_set_hostname(link->dhcp_client, hn);
 746         if (r == -EINVAL && hostname)
 747                 /* Ignore error when the machine's hostname is not suitable to send in DHCP packet. */
 748                 log_link_warning_errno(link, r, "DHCP4 CLIENT: Failed to set hostname from kernel hostname, ignoring: %m");
 749         else if (r < 0)
 750                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set hostname: %m");
 751
 752         return 0;
 753 }
 754
 755 static bool promote_secondaries_enabled(const char *ifname) {
 756         _cleanup_free_ char *promote_secondaries_sysctl = NULL;
 757         char *promote_secondaries_path;
 758         int r;
 759
 760         promote_secondaries_path = strjoina("net/ipv4/conf/", ifname, "/promote_secondaries");
 761         r = sysctl_read(promote_secondaries_path, &promote_secondaries_sysctl);
 762         if (r < 0) {
 763                 log_debug_errno(r, "Cannot read sysctl %s", promote_secondaries_path);
 764                 return false;
 765         }
 766
 767         truncate_nl(promote_secondaries_sysctl);
 768         r = parse_boolean(promote_secondaries_sysctl);
 769         if (r < 0)
 770                 log_warning_errno(r, "Cannot parse sysctl %s with content %s as boolean", promote_secondaries_path, promote_secondaries_sysctl);
 771         return r > 0;
 772 }
 773
 774 /* dhcp4_set_promote_secondaries will ensure this interface has
 775  * the "promote_secondaries" option in the kernel set. If this sysctl
 776  * is not set DHCP will work only as long as the IP address does not
 777  * changes between leases. The kernel will remove all secondary IP
 778  * addresses of an interface otherwise. The way systemd-network works
 779  * is that the new IP of a lease is added as a secondary IP and when
 780  * the primary one expires it relies on the kernel to promote the
 781  * secondary IP. See also https://github.com/systemd/systemd/issues/7163
 782  */
 783 int dhcp4_set_promote_secondaries(Link *link) {
 784         int r;
 785
 786         assert(link);
 787         assert(link->network);
 788         assert(link->network->dhcp & ADDRESS_FAMILY_IPV4);
 789
 790         /* check if the kernel has promote_secondaries enabled for our
 791          * interface. If it is not globally enabled or enabled for the
 792          * specific interface we must either enable it.
 793          */
 794         if (!(promote_secondaries_enabled("all") || promote_secondaries_enabled(link->ifname))) {
 795                 char *promote_secondaries_path = NULL;
 796
 797                 log_link_debug(link, "promote_secondaries is unset, setting it");
 798                 promote_secondaries_path = strjoina("net/ipv4/conf/", link->ifname, "/promote_secondaries");
 799                 r = sysctl_write(promote_secondaries_path, "1");
 800                 if (r < 0)
 801                         log_link_warning_errno(link, r, "cannot set sysctl %s to 1", promote_secondaries_path);
 802                 return r > 0;
 803         }
 804
 805         return 0;
 806 }
 807
 808 int dhcp4_set_client_identifier(Link *link) {
 809         int r;
 810
 811         assert(link);
 812         assert(link->network);
 813         assert(link->dhcp_client);
 814
 815         switch (link->network->dhcp_client_identifier) {
 816         case DHCP_CLIENT_ID_DUID: {
 817                 /* If configured, apply user specified DUID and IAID */
 818                 const DUID *duid = link_get_duid(link);
 819
 820                 if (duid->type == DUID_TYPE_LLT && duid->raw_data_len == 0)
 821                         r = sd_dhcp_client_set_iaid_duid_llt(link->dhcp_client,
 822                                                              link->network->iaid_set,
 823                                                              link->network->iaid,
 824                                                              duid->llt_time);
 825                 else
 826                         r = sd_dhcp_client_set_iaid_duid(link->dhcp_client,
 827                                                          link->network->iaid_set,
 828                                                          link->network->iaid,
 829                                                          duid->type,
 830                                                          duid->raw_data_len > 0 ? duid->raw_data : NULL,
 831                                                          duid->raw_data_len);
 832                 if (r < 0)
 833                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set IAID+DUID: %m");
 834                 break;
 835         }
 836         case DHCP_CLIENT_ID_DUID_ONLY: {
 837                 /* If configured, apply user specified DUID */
 838                 const DUID *duid = link_get_duid(link);
 839
 840                 if (duid->type == DUID_TYPE_LLT && duid->raw_data_len == 0)
 841                         r = sd_dhcp_client_set_duid_llt(link->dhcp_client,
 842                                                         duid->llt_time);
 843                 else
 844                         r = sd_dhcp_client_set_duid(link->dhcp_client,
 845                                                     duid->type,
 846                                                     duid->raw_data_len > 0 ? duid->raw_data : NULL,
 847                                                     duid->raw_data_len);
 848                 if (r < 0)
 849                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set DUID: %m");
 850                 break;
 851         }
 852         case DHCP_CLIENT_ID_MAC:
 853                 r = sd_dhcp_client_set_client_id(link->dhcp_client,
 854                                                  ARPHRD_ETHER,
 855                                                  (const uint8_t *) &link->mac,
 856                                                  sizeof(link->mac));
 857                 if (r < 0)
 858                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set client ID: %m");
 859                 break;
 860         default:
 861                 assert_not_reached("Unknown client identifier type.");
 862         }
 863
 864         return 0;
 865 }
 866
 867 int dhcp4_configure(Link *link) {
 868         int r;
 869
 870         assert(link);
 871         assert(link->network);
 872         assert(link->network->dhcp & ADDRESS_FAMILY_IPV4);
 873
 874         if (!link->dhcp_client) {
 875                 r = sd_dhcp_client_new(&link->dhcp_client, link->network->dhcp_anonymize);
 876                 if (r == -ENOMEM)
 877                         return log_oom();
 878                 if (r < 0)
 879                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to create DHCP4 client: %m");
 880         }
 881
 882         r = sd_dhcp_client_attach_event(link->dhcp_client, NULL, 0);
 883         if (r < 0)
 884                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to attach event: %m");
 885
 886         r = sd_dhcp_client_set_mac(link->dhcp_client,
 887                                    (const uint8_t *) &link->mac,
 888                                    sizeof (link->mac), ARPHRD_ETHER);
 889         if (r < 0)
 890                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set MAC address: %m");
 891
 892         r = sd_dhcp_client_set_ifindex(link->dhcp_client, link->ifindex);
 893         if (r < 0)
 894                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set ifindex: %m");
 895
 896         r = sd_dhcp_client_set_callback(link->dhcp_client, dhcp4_handler, link);
 897         if (r < 0)
 898                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set callback: %m");
 899
 900         r = sd_dhcp_client_set_request_broadcast(link->dhcp_client,
 901                                                  link->network->dhcp_broadcast);
 902         if (r < 0)
 903                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for broadcast: %m");
 904
 905         if (link->mtu) {
 906                 r = sd_dhcp_client_set_mtu(link->dhcp_client, link->mtu);
 907                 if (r < 0)
 908                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set MTU: %m");
 909         }
 910
 911         if (link->network->dhcp_use_mtu) {
 912                 r = sd_dhcp_client_set_request_option(link->dhcp_client,
 913                                                       SD_DHCP_OPTION_INTERFACE_MTU);
 914                 if (r < 0)
 915                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for MTU: %m");
 916         }
 917
 918         /* NOTE: even if this variable is called "use", it also "sends" PRL
 919          * options, maybe there should be a different configuration variable
 920          * to send or not route options?. */
 921         /* NOTE: when using Anonymize=yes, routes PRL options are sent
 922          * by default, so they don't need to be added here. */
 923         if (link->network->dhcp_use_routes && !link->network->dhcp_anonymize) {
 924                 r = sd_dhcp_client_set_request_option(link->dhcp_client,
 925                                                       SD_DHCP_OPTION_STATIC_ROUTE);
 926                 if (r < 0)
 927                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for static route: %m");
 928
 929                 r = sd_dhcp_client_set_request_option(link->dhcp_client,
 930                                                       SD_DHCP_OPTION_CLASSLESS_STATIC_ROUTE);
 931                 if (r < 0)
 932                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for classless static route: %m");
 933         }
 934
 935         if (link->network->dhcp_use_ntp) {
 936                 r = sd_dhcp_client_set_request_option(link->dhcp_client, SD_DHCP_OPTION_NTP_SERVER);
 937                 if (r < 0)
 938                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for NTP server: %m");
 939         }
 940
 941         if (link->network->dhcp_use_timezone) {
 942                 r = sd_dhcp_client_set_request_option(link->dhcp_client, SD_DHCP_OPTION_NEW_TZDB_TIMEZONE);
 943                 if (r < 0)
 944                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for timezone: %m");
 945         }
 946
 947         r = dhcp4_set_hostname(link);
 948         if (r < 0)
 949                 return r;
 950
 951         if (link->network->dhcp_vendor_class_identifier) {
 952                 r = sd_dhcp_client_set_vendor_class_identifier(link->dhcp_client,
 953                                                                link->network->dhcp_vendor_class_identifier);
 954                 if (r < 0)
 955                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set vendor class identifier: %m");
 956         }
 957
 958         if (link->network->dhcp_user_class) {
 959                 r = sd_dhcp_client_set_user_class(link->dhcp_client, (const char **) link->network->dhcp_user_class);
 960                 if (r < 0)
 961                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set user class: %m");
 962         }
 963
 964         if (link->network->dhcp_client_port) {
 965                 r = sd_dhcp_client_set_client_port(link->dhcp_client, link->network->dhcp_client_port);
 966                 if (r < 0)
 967                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set listen port: %m");
 968         }
 969
 970         if (link->network->dhcp_max_attempts > 0) {
 971                 r = sd_dhcp_client_set_max_attempts(link->dhcp_client, link->network->dhcp_max_attempts);
 972                 if (r < 0)
 973                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set max attempts: %m");
 974         }
 975
 976         return dhcp4_set_client_identifier(link);
 977 }