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_error_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_error_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                         return log_link_error_errno(link, r, "Could not set routes: %m");
 174
 175                 link->dhcp4_messages++;
 176         }
 177
 178         return 0;
 179 }
 180
 181 static int dhcp_remove_routes(Link *link, struct in_addr *address) {
 182         _cleanup_free_ sd_dhcp_route **routes = NULL;
 183         uint32_t table;
 184         int n, i, r;
 185
 186         assert(link);
 187         assert(address);
 188
 189         if (!link->network->dhcp_use_routes)
 190                 return 0;
 191
 192         n = sd_dhcp_lease_get_routes(link->dhcp_lease, &routes);
 193         if (IN_SET(n, 0, -ENODATA)) {
 194                 log_link_debug(link, "DHCP: No routes received from DHCP server: %m");
 195                 return 0;
 196         } else if (n < 0)
 197                 return log_link_error_errno(link, n, "DHCP error: could not get routes: %m");
 198
 199         table = link_get_dhcp_route_table(link);
 200
 201         for (i = 0; i < n; i++) {
 202                 _cleanup_(route_freep) Route *route = NULL;
 203
 204                 r = route_new(&route);
 205                 if (r < 0)
 206                         return log_oom();
 207
 208                 route->family = AF_INET;
 209                 assert_se(sd_dhcp_route_get_gateway(routes[i], &route->gw.in) >= 0);
 210                 assert_se(sd_dhcp_route_get_destination(routes[i], &route->dst.in) >= 0);
 211                 assert_se(sd_dhcp_route_get_destination_prefix_length(routes[i], &route->dst_prefixlen) >= 0);
 212                 route->priority = link->network->dhcp_route_metric;
 213                 route->table = table;
 214                 route->scope = route_scope_from_address(route, address);
 215
 216                 (void) route_remove(route, link, NULL);
 217         }
 218
 219         return n;
 220 }
 221
 222 static int dhcp_remove_router(Link *link, struct in_addr *address) {
 223         _cleanup_(route_freep) Route *route_gw = NULL, *route = NULL;
 224         const struct in_addr *router;
 225         uint32_t table;
 226         int r;
 227
 228         assert(link);
 229         assert(address);
 230
 231         if (!link->network->dhcp_use_routes)
 232                 return 0;
 233
 234         r = sd_dhcp_lease_get_router(link->dhcp_lease, &router);
 235         if (IN_SET(r, 0, -ENODATA)) {
 236                 log_link_debug(link, "DHCP: No gateway received from DHCP server.");
 237                 return 0;
 238         } else if (r < 0)
 239                 return log_link_error_errno(link, r, "DHCP error: could not get gateway: %m");
 240         else if (in4_addr_is_null(&router[0])) {
 241                 log_link_info(link, "DHCP: Received gateway is null, ignoring.");
 242                 return 0;
 243         }
 244
 245         table = link_get_dhcp_route_table(link);
 246
 247         r = route_new(&route_gw);
 248         if (r < 0)
 249                 return log_oom();
 250
 251         route_gw->family = AF_INET;
 252         route_gw->dst.in = router[0];
 253         route_gw->dst_prefixlen = 32;
 254         route_gw->prefsrc.in = *address;
 255         route_gw->scope = RT_SCOPE_LINK;
 256         route_gw->protocol = RTPROT_DHCP;
 257         route_gw->priority = link->network->dhcp_route_metric;
 258         route_gw->table = table;
 259
 260         (void) route_remove(route_gw, link, NULL);
 261
 262         r = route_new(&route);
 263         if (r < 0)
 264                 return log_oom();
 265
 266         route->family = AF_INET;
 267         route->gw.in = router[0];
 268         route->prefsrc.in = *address;
 269         route->protocol = RTPROT_DHCP;
 270         route->priority = link->network->dhcp_route_metric;
 271         route->table = table;
 272
 273         (void) route_remove(route, link, NULL);
 274
 275         return 0;
 276 }
 277
 278 static int dhcp_remove_address(Link *link, struct in_addr *address) {
 279         _cleanup_(address_freep) Address *a = NULL;
 280         struct in_addr netmask;
 281         int r;
 282
 283         assert(link);
 284         assert(address);
 285
 286         if (in4_addr_is_null(address))
 287                 return 0;
 288
 289         r = address_new(&a);
 290         if (r < 0)
 291                 return log_oom();
 292
 293         a->family = AF_INET;
 294         a->in_addr.in = *address;
 295
 296         if (sd_dhcp_lease_get_netmask(link->dhcp_lease, &netmask) >= 0)
 297                 a->prefixlen = in4_addr_netmask_to_prefixlen(&netmask);
 298
 299         (void) address_remove(a, link, NULL);
 300
 301         return 0;
 302 }
 303
 304 static int dhcp_reset_mtu(Link *link) {
 305         uint16_t mtu;
 306         int r;
 307
 308         assert(link);
 309
 310         if (!link->network->dhcp_use_mtu)
 311                 return 0;
 312
 313         r = sd_dhcp_lease_get_mtu(link->dhcp_lease, &mtu);
 314         if (r < 0)
 315                 return r;
 316
 317         if (link->original_mtu == mtu)
 318                 return 0;
 319
 320         r = link_set_mtu(link, link->original_mtu);
 321         if (r < 0) {
 322                 log_link_error_errno(link, r, "DHCP error: could not reset MTU: %m");
 323                 link_enter_failed(link);
 324                 return r;
 325         }
 326
 327         return 0;
 328 }
 329
 330 static int dhcp_reset_hostname(Link *link) {
 331         const char *hostname;
 332         int r;
 333
 334         assert(link);
 335
 336         if (!link->network->dhcp_use_hostname)
 337                 return 0;
 338
 339         hostname = link->network->dhcp_hostname;
 340         if (!hostname)
 341                 (void) sd_dhcp_lease_get_hostname(link->dhcp_lease, &hostname);
 342
 343         if (!hostname)
 344                 return 0;
 345
 346         /* If a hostname was set due to the lease, then unset it now. */
 347         r = manager_set_hostname(link->manager, NULL);
 348         if (r < 0)
 349                 return log_link_error_errno(link, r, "DHCP error: Failed to reset transient hostname: %m");
 350
 351         return 0;
 352 }
 353
 354 static int dhcp_lease_lost(Link *link) {
 355         struct in_addr address = {};
 356
 357         assert(link);
 358         assert(link->dhcp_lease);
 359
 360         log_link_warning(link, "DHCP lease lost");
 361
 362         link->dhcp4_configured = false;
 363
 364         (void) sd_dhcp_lease_get_address(link->dhcp_lease, &address);
 365         (void) dhcp_remove_routes(link, &address);
 366         (void) dhcp_remove_router(link, &address);
 367         (void) dhcp_remove_address(link, &address);
 368         (void) dhcp_reset_mtu(link);
 369         (void) dhcp_reset_hostname(link);
 370
 371         link->dhcp_lease = sd_dhcp_lease_unref(link->dhcp_lease);
 372         link_dirty(link);
 373
 374         return 0;
 375 }
 376
 377 static int dhcp4_address_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
 378         int r;
 379
 380         assert(link);
 381
 382         r = sd_netlink_message_get_errno(m);
 383         if (r < 0 && r != -EEXIST) {
 384                 log_link_error_errno(link, r, "Could not set DHCPv4 address: %m");
 385                 link_enter_failed(link);
 386         } else if (r >= 0)
 387                 manager_rtnl_process_address(rtnl, m, link->manager);
 388
 389         r = link_set_dhcp_routes(link);
 390         if (r < 0) {
 391                 link_enter_failed(link);
 392                 return 1;
 393         }
 394
 395         /* Add back static routes since kernel removes while DHCPv4 address is removed from when lease expires */
 396         link_request_set_routes(link);
 397
 398         if (link->dhcp4_messages == 0) {
 399                 link->dhcp4_configured = true;
 400                 link_check_ready(link);
 401         }
 402
 403         return 1;
 404 }
 405
 406 static int dhcp4_update_address(Link *link,
 407                                 struct in_addr *address,
 408                                 struct in_addr *netmask,
 409                                 uint32_t lifetime) {
 410         _cleanup_(address_freep) Address *addr = NULL;
 411         unsigned prefixlen;
 412         int r;
 413
 414         assert(address);
 415         assert(netmask);
 416         assert(lifetime);
 417
 418         prefixlen = in4_addr_netmask_to_prefixlen(netmask);
 419
 420         r = address_new(&addr);
 421         if (r < 0)
 422                 return r;
 423
 424         addr->family = AF_INET;
 425         addr->in_addr.in.s_addr = address->s_addr;
 426         addr->cinfo.ifa_prefered = lifetime;
 427         addr->cinfo.ifa_valid = lifetime;
 428         addr->prefixlen = prefixlen;
 429         addr->broadcast.s_addr = address->s_addr | ~netmask->s_addr;
 430
 431         /* allow reusing an existing address and simply update its lifetime
 432          * in case it already exists */
 433         r = address_configure(addr, link, dhcp4_address_handler, true);
 434         if (r < 0)
 435                 return r;
 436
 437         return 0;
 438 }
 439
 440 static int dhcp_lease_renew(sd_dhcp_client *client, Link *link) {
 441         sd_dhcp_lease *lease;
 442         struct in_addr address;
 443         struct in_addr netmask;
 444         uint32_t lifetime = CACHE_INFO_INFINITY_LIFE_TIME;
 445         int r;
 446
 447         assert(link);
 448         assert(client);
 449         assert(link->network);
 450
 451         r = sd_dhcp_client_get_lease(client, &lease);
 452         if (r < 0)
 453                 return log_link_warning_errno(link, r, "DHCP error: no lease: %m");
 454
 455         sd_dhcp_lease_unref(link->dhcp_lease);
 456         link->dhcp4_configured = false;
 457         link->dhcp_lease = sd_dhcp_lease_ref(lease);
 458         link_dirty(link);
 459
 460         r = sd_dhcp_lease_get_address(lease, &address);
 461         if (r < 0)
 462                 return log_link_warning_errno(link, r, "DHCP error: no address: %m");
 463
 464         r = sd_dhcp_lease_get_netmask(lease, &netmask);
 465         if (r < 0)
 466                 return log_link_warning_errno(link, r, "DHCP error: no netmask: %m");
 467
 468         if (!FLAGS_SET(link->network->keep_configuration, KEEP_CONFIGURATION_DHCP)) {
 469                 r = sd_dhcp_lease_get_lifetime(link->dhcp_lease, &lifetime);
 470                 if (r < 0)
 471                         return log_link_warning_errno(link, r, "DHCP error: no lifetime: %m");
 472         }
 473
 474         r = dhcp4_update_address(link, &address, &netmask, lifetime);
 475         if (r < 0) {
 476                 log_link_warning_errno(link, r, "Could not update IP address: %m");
 477                 link_enter_failed(link);
 478                 return r;
 479         }
 480
 481         return 0;
 482 }
 483
 484 static int dhcp_lease_acquired(sd_dhcp_client *client, Link *link) {
 485         const struct in_addr *router;
 486         sd_dhcp_lease *lease;
 487         struct in_addr address;
 488         struct in_addr netmask;
 489         unsigned prefixlen;
 490         uint32_t lifetime = CACHE_INFO_INFINITY_LIFE_TIME;
 491         int r;
 492
 493         assert(client);
 494         assert(link);
 495
 496         link->dhcp4_configured = false;
 497
 498         r = sd_dhcp_client_get_lease(client, &lease);
 499         if (r < 0)
 500                 return log_link_error_errno(link, r, "DHCP error: No lease: %m");
 501
 502         r = sd_dhcp_lease_get_address(lease, &address);
 503         if (r < 0)
 504                 return log_link_error_errno(link, r, "DHCP error: No address: %m");
 505
 506         r = sd_dhcp_lease_get_netmask(lease, &netmask);
 507         if (r < 0)
 508                 return log_link_error_errno(link, r, "DHCP error: No netmask: %m");
 509
 510         prefixlen = in4_addr_netmask_to_prefixlen(&netmask);
 511
 512         r = sd_dhcp_lease_get_router(lease, &router);
 513         if (r < 0 && r != -ENODATA)
 514                 return log_link_error_errno(link, r, "DHCP error: Could not get gateway: %m");
 515
 516         if (r > 0 && !in4_addr_is_null(&router[0]))
 517                 log_struct(LOG_INFO,
 518                            LOG_LINK_INTERFACE(link),
 519                            LOG_LINK_MESSAGE(link, "DHCPv4 address %u.%u.%u.%u/%u via %u.%u.%u.%u",
 520                                             ADDRESS_FMT_VAL(address),
 521                                             prefixlen,
 522                                             ADDRESS_FMT_VAL(router[0])),
 523                            "ADDRESS=%u.%u.%u.%u", ADDRESS_FMT_VAL(address),
 524                            "PREFIXLEN=%u", prefixlen,
 525                            "GATEWAY=%u.%u.%u.%u", ADDRESS_FMT_VAL(router[0]));
 526         else
 527                 log_struct(LOG_INFO,
 528                            LOG_LINK_INTERFACE(link),
 529                            LOG_LINK_MESSAGE(link, "DHCPv4 address %u.%u.%u.%u/%u",
 530                                             ADDRESS_FMT_VAL(address),
 531                                             prefixlen),
 532                            "ADDRESS=%u.%u.%u.%u", ADDRESS_FMT_VAL(address),
 533                            "PREFIXLEN=%u", prefixlen);
 534
 535         link->dhcp_lease = sd_dhcp_lease_ref(lease);
 536         link_dirty(link);
 537
 538         if (link->network->dhcp_use_mtu) {
 539                 uint16_t mtu;
 540
 541                 r = sd_dhcp_lease_get_mtu(lease, &mtu);
 542                 if (r >= 0) {
 543                         r = link_set_mtu(link, mtu);
 544                         if (r < 0)
 545                                 log_link_error_errno(link, r, "Failed to set MTU to %" PRIu16 ": %m", mtu);
 546                 }
 547         }
 548
 549         if (link->network->dhcp_use_hostname) {
 550                 const char *dhcpname = NULL;
 551                 _cleanup_free_ char *hostname = NULL;
 552
 553                 if (link->network->dhcp_hostname)
 554                         dhcpname = link->network->dhcp_hostname;
 555                 else
 556                         (void) sd_dhcp_lease_get_hostname(lease, &dhcpname);
 557
 558                 if (dhcpname) {
 559                         r = shorten_overlong(dhcpname, &hostname);
 560                         if (r < 0)
 561                                 log_link_warning_errno(link, r, "Unable to shorten overlong DHCP hostname '%s', ignoring: %m", dhcpname);
 562                         if (r == 1)
 563                                 log_link_notice(link, "Overlong DHCP hostname received, shortened from '%s' to '%s'", dhcpname, hostname);
 564                 }
 565
 566                 if (hostname) {
 567                         r = manager_set_hostname(link->manager, hostname);
 568                         if (r < 0)
 569                                 log_link_error_errno(link, r, "Failed to set transient hostname to '%s': %m", hostname);
 570                 }
 571         }
 572
 573         if (link->network->dhcp_use_timezone) {
 574                 const char *tz = NULL;
 575
 576                 (void) sd_dhcp_lease_get_timezone(link->dhcp_lease, &tz);
 577
 578                 if (tz) {
 579                         r = manager_set_timezone(link->manager, tz);
 580                         if (r < 0)
 581                                 log_link_error_errno(link, r, "Failed to set timezone to '%s': %m", tz);
 582                 }
 583         }
 584
 585         if (!FLAGS_SET(link->network->keep_configuration, KEEP_CONFIGURATION_DHCP)) {
 586                 r = sd_dhcp_lease_get_lifetime(link->dhcp_lease, &lifetime);
 587                 if (r < 0)
 588                         return log_link_warning_errno(link, r, "DHCP error: no lifetime: %m");
 589         }
 590
 591         r = dhcp4_update_address(link, &address, &netmask, lifetime);
 592         if (r < 0) {
 593                 log_link_warning_errno(link, r, "Could not update IP address: %m");
 594                 link_enter_failed(link);
 595                 return r;
 596         }
 597
 598         return 0;
 599 }
 600
 601 static int dhcp_server_is_black_listed(Link *link, sd_dhcp_client *client) {
 602         sd_dhcp_lease *lease;
 603         struct in_addr addr;
 604         int r;
 605
 606         assert(link);
 607         assert(link->network);
 608         assert(client);
 609
 610         r = sd_dhcp_client_get_lease(client, &lease);
 611         if (r < 0)
 612                 return log_link_error_errno(link, r, "Failed to get DHCP lease: %m");
 613
 614         r = sd_dhcp_lease_get_server_identifier(lease, &addr);
 615         if (r < 0)
 616                 return log_link_debug_errno(link, r, "Failed to get DHCP server ip address: %m");
 617
 618         if (set_contains(link->network->dhcp_black_listed_ip, UINT32_TO_PTR(addr.s_addr))) {
 619                 log_struct(LOG_DEBUG,
 620                            LOG_LINK_INTERFACE(link),
 621                            LOG_LINK_MESSAGE(link, "DHCPv4 ip '%u.%u.%u.%u' found in black listed ip addresses, ignoring offer",
 622                                             ADDRESS_FMT_VAL(addr)));
 623                 return true;
 624         }
 625
 626         return false;
 627 }
 628
 629 static int dhcp4_handler(sd_dhcp_client *client, int event, void *userdata) {
 630         Link *link = userdata;
 631         int r;
 632
 633         assert(link);
 634         assert(link->network);
 635         assert(link->manager);
 636
 637         if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
 638                 return 0;
 639
 640         switch (event) {
 641                 case SD_DHCP_CLIENT_EVENT_STOP:
 642
 643                         if (link_ipv4ll_enabled(link, ADDRESS_FAMILY_FALLBACK_IPV4)) {
 644                                 assert(link->ipv4ll);
 645
 646                                 log_link_debug(link, "DHCP client is stopped. Acquiring IPv4 link-local address");
 647
 648                                 r = sd_ipv4ll_start(link->ipv4ll);
 649                                 if (r < 0)
 650                                         return log_link_warning_errno(link, r, "Could not acquire IPv4 link-local address: %m");
 651                         }
 652
 653                         if (FLAGS_SET(link->network->keep_configuration, KEEP_CONFIGURATION_DHCP)) {
 654                                 log_link_notice(link, "DHCPv4 connection considered critical, ignoring request to reconfigure it.");
 655                                 return 0;
 656                         }
 657
 658                         if (link->network->dhcp_send_release)
 659                                 (void) sd_dhcp_client_send_release(client);
 660
 661                         if (link->dhcp_lease) {
 662                                 r = dhcp_lease_lost(link);
 663                                 if (r < 0) {
 664                                         link_enter_failed(link);
 665                                         return r;
 666                                 }
 667                         }
 668
 669                         break;
 670                 case SD_DHCP_CLIENT_EVENT_EXPIRED:
 671                 case SD_DHCP_CLIENT_EVENT_IP_CHANGE:
 672
 673                         if (FLAGS_SET(link->network->keep_configuration, KEEP_CONFIGURATION_DHCP)) {
 674                                 log_link_notice(link, "DHCPv4 connection considered critical, ignoring request to reconfigure it.");
 675                                 return 0;
 676                         }
 677
 678                         if (link->dhcp_lease) {
 679                                 r = dhcp_lease_lost(link);
 680                                 if (r < 0) {
 681                                         link_enter_failed(link);
 682                                         return r;
 683                                 }
 684                         }
 685
 686                         if (event == SD_DHCP_CLIENT_EVENT_IP_CHANGE) {
 687                                 r = dhcp_lease_acquired(client, link);
 688                                 if (r < 0) {
 689                                         link_enter_failed(link);
 690                                         return r;
 691                                 }
 692                         }
 693
 694                         break;
 695                 case SD_DHCP_CLIENT_EVENT_RENEW:
 696                         r = dhcp_lease_renew(client, link);
 697                         if (r < 0) {
 698                                 link_enter_failed(link);
 699                                 return r;
 700                         }
 701                         break;
 702                 case SD_DHCP_CLIENT_EVENT_IP_ACQUIRE:
 703                         r = dhcp_lease_acquired(client, link);
 704                         if (r < 0) {
 705                                 link_enter_failed(link);
 706                                 return r;
 707                         }
 708                         break;
 709                 case SD_DHCP_CLIENT_EVENT_SELECTING:
 710                         r = dhcp_server_is_black_listed(link, client);
 711                         if (r < 0)
 712                                 return r;
 713                         if (r != 0)
 714                                 return -ENOMSG;
 715                         break;
 716                 default:
 717                         if (event < 0)
 718                                 log_link_warning_errno(link, event, "DHCP error: Client failed: %m");
 719                         else
 720                                 log_link_warning(link, "DHCP unknown event: %i", event);
 721                         break;
 722         }
 723
 724         return 0;
 725 }
 726
 727 static int dhcp4_set_hostname(Link *link) {
 728         _cleanup_free_ char *hostname = NULL;
 729         const char *hn;
 730         int r;
 731
 732         assert(link);
 733
 734         if (!link->network->dhcp_send_hostname)
 735                 hn = NULL;
 736         else if (link->network->dhcp_hostname)
 737                 hn = link->network->dhcp_hostname;
 738         else {
 739                 r = gethostname_strict(&hostname);
 740                 if (r < 0 && r != -ENXIO) /* ENXIO: no hostname set or hostname is "localhost" */
 741                         return r;
 742
 743                 hn = hostname;
 744         }
 745
 746         r = sd_dhcp_client_set_hostname(link->dhcp_client, hn);
 747         if (r == -EINVAL && hostname)
 748                 /* Ignore error when the machine's hostname is not suitable to send in DHCP packet. */
 749                 log_link_warning_errno(link, r, "DHCP4 CLIENT: Failed to set hostname from kernel hostname, ignoring: %m");
 750         else if (r < 0)
 751                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set hostname: %m");
 752
 753         return 0;
 754 }
 755
 756 static bool promote_secondaries_enabled(const char *ifname) {
 757         _cleanup_free_ char *promote_secondaries_sysctl = NULL;
 758         char *promote_secondaries_path;
 759         int r;
 760
 761         promote_secondaries_path = strjoina("net/ipv4/conf/", ifname, "/promote_secondaries");
 762         r = sysctl_read(promote_secondaries_path, &promote_secondaries_sysctl);
 763         if (r < 0) {
 764                 log_debug_errno(r, "Cannot read sysctl %s", promote_secondaries_path);
 765                 return false;
 766         }
 767
 768         truncate_nl(promote_secondaries_sysctl);
 769         r = parse_boolean(promote_secondaries_sysctl);
 770         if (r < 0)
 771                 log_warning_errno(r, "Cannot parse sysctl %s with content %s as boolean", promote_secondaries_path, promote_secondaries_sysctl);
 772         return r > 0;
 773 }
 774
 775 /* dhcp4_set_promote_secondaries will ensure this interface has
 776  * the "promote_secondaries" option in the kernel set. If this sysctl
 777  * is not set DHCP will work only as long as the IP address does not
 778  * changes between leases. The kernel will remove all secondary IP
 779  * addresses of an interface otherwise. The way systemd-network works
 780  * is that the new IP of a lease is added as a secondary IP and when
 781  * the primary one expires it relies on the kernel to promote the
 782  * secondary IP. See also https://github.com/systemd/systemd/issues/7163
 783  */
 784 int dhcp4_set_promote_secondaries(Link *link) {
 785         int r;
 786
 787         assert(link);
 788         assert(link->network);
 789         assert(link->network->dhcp & ADDRESS_FAMILY_IPV4);
 790
 791         /* check if the kernel has promote_secondaries enabled for our
 792          * interface. If it is not globally enabled or enabled for the
 793          * specific interface we must either enable it.
 794          */
 795         if (!(promote_secondaries_enabled("all") || promote_secondaries_enabled(link->ifname))) {
 796                 char *promote_secondaries_path = NULL;
 797
 798                 log_link_debug(link, "promote_secondaries is unset, setting it");
 799                 promote_secondaries_path = strjoina("net/ipv4/conf/", link->ifname, "/promote_secondaries");
 800                 r = sysctl_write(promote_secondaries_path, "1");
 801                 if (r < 0)
 802                         log_link_warning_errno(link, r, "cannot set sysctl %s to 1", promote_secondaries_path);
 803                 return r > 0;
 804         }
 805
 806         return 0;
 807 }
 808
 809 int dhcp4_set_client_identifier(Link *link) {
 810         int r;
 811
 812         assert(link);
 813         assert(link->network);
 814         assert(link->dhcp_client);
 815
 816         switch (link->network->dhcp_client_identifier) {
 817         case DHCP_CLIENT_ID_DUID: {
 818                 /* If configured, apply user specified DUID and IAID */
 819                 const DUID *duid = link_get_duid(link);
 820
 821                 if (duid->type == DUID_TYPE_LLT && duid->raw_data_len == 0)
 822                         r = sd_dhcp_client_set_iaid_duid_llt(link->dhcp_client,
 823                                                              link->network->iaid_set,
 824                                                              link->network->iaid,
 825                                                              duid->llt_time);
 826                 else
 827                         r = sd_dhcp_client_set_iaid_duid(link->dhcp_client,
 828                                                          link->network->iaid_set,
 829                                                          link->network->iaid,
 830                                                          duid->type,
 831                                                          duid->raw_data_len > 0 ? duid->raw_data : NULL,
 832                                                          duid->raw_data_len);
 833                 if (r < 0)
 834                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set IAID+DUID: %m");
 835                 break;
 836         }
 837         case DHCP_CLIENT_ID_DUID_ONLY: {
 838                 /* If configured, apply user specified DUID */
 839                 const DUID *duid = link_get_duid(link);
 840
 841                 if (duid->type == DUID_TYPE_LLT && duid->raw_data_len == 0)
 842                         r = sd_dhcp_client_set_duid_llt(link->dhcp_client,
 843                                                         duid->llt_time);
 844                 else
 845                         r = sd_dhcp_client_set_duid(link->dhcp_client,
 846                                                     duid->type,
 847                                                     duid->raw_data_len > 0 ? duid->raw_data : NULL,
 848                                                     duid->raw_data_len);
 849                 if (r < 0)
 850                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set DUID: %m");
 851                 break;
 852         }
 853         case DHCP_CLIENT_ID_MAC:
 854                 r = sd_dhcp_client_set_client_id(link->dhcp_client,
 855                                                  ARPHRD_ETHER,
 856                                                  (const uint8_t *) &link->mac,
 857                                                  sizeof(link->mac));
 858                 if (r < 0)
 859                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set client ID: %m");
 860                 break;
 861         default:
 862                 assert_not_reached("Unknown client identifier type.");
 863         }
 864
 865         return 0;
 866 }
 867
 868 int dhcp4_configure(Link *link) {
 869         int r;
 870
 871         assert(link);
 872         assert(link->network);
 873         assert(link->network->dhcp & ADDRESS_FAMILY_IPV4);
 874
 875         if (!link->dhcp_client) {
 876                 r = sd_dhcp_client_new(&link->dhcp_client, link->network->dhcp_anonymize);
 877                 if (r == -ENOMEM)
 878                         return log_oom();
 879                 if (r < 0)
 880                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to create DHCP4 client: %m");
 881         }
 882
 883         r = sd_dhcp_client_attach_event(link->dhcp_client, NULL, 0);
 884         if (r < 0)
 885                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to attach event: %m");
 886
 887         r = sd_dhcp_client_set_mac(link->dhcp_client,
 888                                    (const uint8_t *) &link->mac,
 889                                    sizeof (link->mac), ARPHRD_ETHER);
 890         if (r < 0)
 891                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set MAC address: %m");
 892
 893         r = sd_dhcp_client_set_ifindex(link->dhcp_client, link->ifindex);
 894         if (r < 0)
 895                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set ifindex: %m");
 896
 897         r = sd_dhcp_client_set_callback(link->dhcp_client, dhcp4_handler, link);
 898         if (r < 0)
 899                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set callback: %m");
 900
 901         r = sd_dhcp_client_set_request_broadcast(link->dhcp_client,
 902                                                  link->network->dhcp_broadcast);
 903         if (r < 0)
 904                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for broadcast: %m");
 905
 906         if (link->mtu) {
 907                 r = sd_dhcp_client_set_mtu(link->dhcp_client, link->mtu);
 908                 if (r < 0)
 909                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set MTU: %m");
 910         }
 911
 912         if (link->network->dhcp_use_mtu) {
 913                 r = sd_dhcp_client_set_request_option(link->dhcp_client,
 914                                                       SD_DHCP_OPTION_INTERFACE_MTU);
 915                 if (r < 0)
 916                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for MTU: %m");
 917         }
 918
 919         /* NOTE: even if this variable is called "use", it also "sends" PRL
 920          * options, maybe there should be a different configuration variable
 921          * to send or not route options?. */
 922         /* NOTE: when using Anonymize=yes, routes PRL options are sent
 923          * by default, so they don't need to be added here. */
 924         if (link->network->dhcp_use_routes && !link->network->dhcp_anonymize) {
 925                 r = sd_dhcp_client_set_request_option(link->dhcp_client,
 926                                                       SD_DHCP_OPTION_STATIC_ROUTE);
 927                 if (r < 0)
 928                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for static route: %m");
 929
 930                 r = sd_dhcp_client_set_request_option(link->dhcp_client,
 931                                                       SD_DHCP_OPTION_CLASSLESS_STATIC_ROUTE);
 932                 if (r < 0)
 933                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for classless static route: %m");
 934         }
 935
 936         if (link->network->dhcp_use_ntp) {
 937                 r = sd_dhcp_client_set_request_option(link->dhcp_client, SD_DHCP_OPTION_NTP_SERVER);
 938                 if (r < 0)
 939                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for NTP server: %m");
 940         }
 941
 942         if (link->network->dhcp_use_timezone) {
 943                 r = sd_dhcp_client_set_request_option(link->dhcp_client, SD_DHCP_OPTION_NEW_TZDB_TIMEZONE);
 944                 if (r < 0)
 945                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for timezone: %m");
 946         }
 947
 948         r = dhcp4_set_hostname(link);
 949         if (r < 0)
 950                 return r;
 951
 952         if (link->network->dhcp_vendor_class_identifier) {
 953                 r = sd_dhcp_client_set_vendor_class_identifier(link->dhcp_client,
 954                                                                link->network->dhcp_vendor_class_identifier);
 955                 if (r < 0)
 956                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set vendor class identifier: %m");
 957         }
 958
 959         if (link->network->dhcp_user_class) {
 960                 r = sd_dhcp_client_set_user_class(link->dhcp_client, (const char **) link->network->dhcp_user_class);
 961                 if (r < 0)
 962                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set user class: %m");
 963         }
 964
 965         if (link->network->dhcp_client_port) {
 966                 r = sd_dhcp_client_set_client_port(link->dhcp_client, link->network->dhcp_client_port);
 967                 if (r < 0)
 968                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set listen port: %m");
 969         }
 970
 971         if (link->network->dhcp_max_attempts > 0) {
 972                 r = sd_dhcp_client_set_max_attempts(link->dhcp_client, link->network->dhcp_max_attempts);
 973                 if (r < 0)
 974                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set max attempts: %m");
 975         }
 976
 977         return dhcp4_set_client_identifier(link);
 978 }