src/network/networkd-dhcp4.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <netinet/ether.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_lease_lost(Link *link) {
 185         _cleanup_(address_freep) Address *address = NULL;
 186         const struct in_addr *router;
 187         struct in_addr addr;
 188         struct in_addr netmask;
 189         unsigned prefixlen = 0;
 190         int r;
 191
 192         assert(link);
 193         assert(link->dhcp_lease);
 194
 195         log_link_warning(link, "DHCP lease lost");
 196
 197         if (link->network->dhcp_use_routes) {
 198                 _cleanup_free_ sd_dhcp_route **routes = NULL;
 199                 int n, i;
 200
 201                 n = sd_dhcp_lease_get_routes(link->dhcp_lease, &routes);
 202                 if (n >= 0) {
 203                         for (i = 0; i < n; i++) {
 204                                 _cleanup_(route_freep) Route *route = NULL;
 205
 206                                 r = route_new(&route);
 207                                 if (r >= 0) {
 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
 213                                         route_remove(route, link, NULL);
 214                                 }
 215                         }
 216                 }
 217
 218                 r = sd_dhcp_lease_get_router(link->dhcp_lease, &router);
 219                 if (r > 0 && !in4_addr_is_null(&router[0])) {
 220                         _cleanup_(route_freep) Route *route_gw = NULL;
 221                         _cleanup_(route_freep) Route *route = NULL;
 222
 223                         r = route_new(&route_gw);
 224                         if (r >= 0) {
 225                                 route_gw->family = AF_INET;
 226                                 route_gw->dst.in = router[0];
 227                                 route_gw->dst_prefixlen = 32;
 228                                 route_gw->scope = RT_SCOPE_LINK;
 229
 230                                 route_remove(route_gw, link, NULL);
 231                         }
 232
 233                         r = route_new(&route);
 234                         if (r >= 0) {
 235                                 route->family = AF_INET;
 236                                 route->gw.in = router[0];
 237
 238                                 route_remove(route, link, NULL);
 239                         }
 240                 }
 241         }
 242
 243         r = address_new(&address);
 244         if (r >= 0) {
 245                 r = sd_dhcp_lease_get_address(link->dhcp_lease, &addr);
 246                 if (r >= 0) {
 247                         r = sd_dhcp_lease_get_netmask(link->dhcp_lease, &netmask);
 248                         if (r >= 0)
 249                                 prefixlen = in4_addr_netmask_to_prefixlen(&netmask);
 250
 251                         address->family = AF_INET;
 252                         address->in_addr.in = addr;
 253                         address->prefixlen = prefixlen;
 254
 255                         address_remove(address, link, NULL);
 256                 }
 257         }
 258
 259         if (link->network->dhcp_use_mtu) {
 260                 uint16_t mtu;
 261
 262                 r = sd_dhcp_lease_get_mtu(link->dhcp_lease, &mtu);
 263                 if (r >= 0 && link->original_mtu != mtu) {
 264                         r = link_set_mtu(link, link->original_mtu, true);
 265                         if (r < 0) {
 266                                 log_link_warning(link,
 267                                                  "DHCP error: could not reset MTU");
 268                                 link_enter_failed(link);
 269                                 return r;
 270                         }
 271                 }
 272         }
 273
 274         if (link->network->dhcp_use_hostname) {
 275                 const char *hostname = NULL;
 276
 277                 if (link->network->dhcp_hostname)
 278                         hostname = link->network->dhcp_hostname;
 279                 else
 280                         (void) sd_dhcp_lease_get_hostname(link->dhcp_lease, &hostname);
 281
 282                 if (hostname) {
 283                         /* If a hostname was set due to the lease, then unset it now. */
 284                         r = manager_set_hostname(link->manager, NULL);
 285                         if (r < 0)
 286                                 log_link_warning_errno(link, r, "Failed to reset transient hostname: %m");
 287                 }
 288         }
 289
 290         link->dhcp_lease = sd_dhcp_lease_unref(link->dhcp_lease);
 291         link_dirty(link);
 292         link->dhcp4_configured = false;
 293
 294         return 0;
 295 }
 296
 297 static int dhcp4_address_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
 298         int r;
 299
 300         assert(link);
 301
 302         r = sd_netlink_message_get_errno(m);
 303         if (r < 0 && r != -EEXIST) {
 304                 log_link_error_errno(link, r, "Could not set DHCPv4 address: %m");
 305                 link_enter_failed(link);
 306         } else if (r >= 0)
 307                 manager_rtnl_process_address(rtnl, m, link->manager);
 308
 309         link_set_dhcp_routes(link);
 310
 311         /* Add back static routes since kernel removes while DHCPv4 address is removed from when lease expires */
 312         link_request_set_routes(link);
 313
 314         if (link->dhcp4_messages == 0) {
 315                 link->dhcp4_configured = true;
 316                 link_check_ready(link);
 317         }
 318
 319         return 1;
 320 }
 321
 322 static int dhcp4_update_address(Link *link,
 323                                 struct in_addr *address,
 324                                 struct in_addr *netmask,
 325                                 uint32_t lifetime) {
 326         _cleanup_(address_freep) Address *addr = NULL;
 327         unsigned prefixlen;
 328         int r;
 329
 330         assert(address);
 331         assert(netmask);
 332         assert(lifetime);
 333
 334         prefixlen = in4_addr_netmask_to_prefixlen(netmask);
 335
 336         r = address_new(&addr);
 337         if (r < 0)
 338                 return r;
 339
 340         addr->family = AF_INET;
 341         addr->in_addr.in.s_addr = address->s_addr;
 342         addr->cinfo.ifa_prefered = lifetime;
 343         addr->cinfo.ifa_valid = lifetime;
 344         addr->prefixlen = prefixlen;
 345         addr->broadcast.s_addr = address->s_addr | ~netmask->s_addr;
 346
 347         /* allow reusing an existing address and simply update its lifetime
 348          * in case it already exists */
 349         r = address_configure(addr, link, dhcp4_address_handler, true);
 350         if (r < 0)
 351                 return r;
 352
 353         return 0;
 354 }
 355
 356 static int dhcp_lease_renew(sd_dhcp_client *client, Link *link) {
 357         sd_dhcp_lease *lease;
 358         struct in_addr address;
 359         struct in_addr netmask;
 360         uint32_t lifetime = CACHE_INFO_INFINITY_LIFE_TIME;
 361         int r;
 362
 363         assert(link);
 364         assert(client);
 365         assert(link->network);
 366
 367         r = sd_dhcp_client_get_lease(client, &lease);
 368         if (r < 0)
 369                 return log_link_warning_errno(link, r, "DHCP error: no lease: %m");
 370
 371         sd_dhcp_lease_unref(link->dhcp_lease);
 372         link->dhcp4_configured = false;
 373         link->dhcp_lease = sd_dhcp_lease_ref(lease);
 374         link_dirty(link);
 375
 376         r = sd_dhcp_lease_get_address(lease, &address);
 377         if (r < 0)
 378                 return log_link_warning_errno(link, r, "DHCP error: no address: %m");
 379
 380         r = sd_dhcp_lease_get_netmask(lease, &netmask);
 381         if (r < 0)
 382                 return log_link_warning_errno(link, r, "DHCP error: no netmask: %m");
 383
 384         if (!link->network->dhcp_critical) {
 385                 r = sd_dhcp_lease_get_lifetime(link->dhcp_lease, &lifetime);
 386                 if (r < 0)
 387                         return log_link_warning_errno(link, r, "DHCP error: no lifetime: %m");
 388         }
 389
 390         r = dhcp4_update_address(link, &address, &netmask, lifetime);
 391         if (r < 0) {
 392                 log_link_warning_errno(link, r, "Could not update IP address: %m");
 393                 link_enter_failed(link);
 394                 return r;
 395         }
 396
 397         return 0;
 398 }
 399
 400 static int dhcp_lease_acquired(sd_dhcp_client *client, Link *link) {
 401         const struct in_addr *router;
 402         sd_dhcp_lease *lease;
 403         struct in_addr address;
 404         struct in_addr netmask;
 405         unsigned prefixlen;
 406         uint32_t lifetime = CACHE_INFO_INFINITY_LIFE_TIME;
 407         int r;
 408
 409         assert(client);
 410         assert(link);
 411
 412         r = sd_dhcp_client_get_lease(client, &lease);
 413         if (r < 0)
 414                 return log_link_error_errno(link, r, "DHCP error: No lease: %m");
 415
 416         r = sd_dhcp_lease_get_address(lease, &address);
 417         if (r < 0)
 418                 return log_link_error_errno(link, r, "DHCP error: No address: %m");
 419
 420         r = sd_dhcp_lease_get_netmask(lease, &netmask);
 421         if (r < 0)
 422                 return log_link_error_errno(link, r, "DHCP error: No netmask: %m");
 423
 424         prefixlen = in4_addr_netmask_to_prefixlen(&netmask);
 425
 426         r = sd_dhcp_lease_get_router(lease, &router);
 427         if (r < 0 && r != -ENODATA)
 428                 return log_link_error_errno(link, r, "DHCP error: Could not get gateway: %m");
 429
 430         if (r > 0 && !in4_addr_is_null(&router[0]))
 431                 log_struct(LOG_INFO,
 432                            LOG_LINK_INTERFACE(link),
 433                            LOG_LINK_MESSAGE(link, "DHCPv4 address %u.%u.%u.%u/%u via %u.%u.%u.%u",
 434                                             ADDRESS_FMT_VAL(address),
 435                                             prefixlen,
 436                                             ADDRESS_FMT_VAL(router[0])),
 437                            "ADDRESS=%u.%u.%u.%u", ADDRESS_FMT_VAL(address),
 438                            "PREFIXLEN=%u", prefixlen,
 439                            "GATEWAY=%u.%u.%u.%u", ADDRESS_FMT_VAL(router[0]));
 440         else
 441                 log_struct(LOG_INFO,
 442                            LOG_LINK_INTERFACE(link),
 443                            LOG_LINK_MESSAGE(link, "DHCPv4 address %u.%u.%u.%u/%u",
 444                                             ADDRESS_FMT_VAL(address),
 445                                             prefixlen),
 446                            "ADDRESS=%u.%u.%u.%u", ADDRESS_FMT_VAL(address),
 447                            "PREFIXLEN=%u", prefixlen);
 448
 449         link->dhcp_lease = sd_dhcp_lease_ref(lease);
 450         link_dirty(link);
 451
 452         if (link->network->dhcp_use_mtu) {
 453                 uint16_t mtu;
 454
 455                 r = sd_dhcp_lease_get_mtu(lease, &mtu);
 456                 if (r >= 0) {
 457                         r = link_set_mtu(link, mtu, true);
 458                         if (r < 0)
 459                                 log_link_error_errno(link, r, "Failed to set MTU to %" PRIu16 ": %m", mtu);
 460                 }
 461         }
 462
 463         if (link->network->dhcp_use_hostname) {
 464                 const char *dhcpname = NULL;
 465                 _cleanup_free_ char *hostname = NULL;
 466
 467                 if (link->network->dhcp_hostname)
 468                         dhcpname = link->network->dhcp_hostname;
 469                 else
 470                         (void) sd_dhcp_lease_get_hostname(lease, &dhcpname);
 471
 472                 if (dhcpname) {
 473                         r = shorten_overlong(dhcpname, &hostname);
 474                         if (r < 0)
 475                                 log_link_warning_errno(link, r, "Unable to shorten overlong DHCP hostname '%s', ignoring: %m", dhcpname);
 476                         if (r == 1)
 477                                 log_link_notice(link, "Overlong DHCP hostname received, shortened from '%s' to '%s'", dhcpname, hostname);
 478                 }
 479
 480                 if (hostname) {
 481                         r = manager_set_hostname(link->manager, hostname);
 482                         if (r < 0)
 483                                 log_link_error_errno(link, r, "Failed to set transient hostname to '%s': %m", hostname);
 484                 }
 485         }
 486
 487         if (link->network->dhcp_use_timezone) {
 488                 const char *tz = NULL;
 489
 490                 (void) sd_dhcp_lease_get_timezone(link->dhcp_lease, &tz);
 491
 492                 if (tz) {
 493                         r = manager_set_timezone(link->manager, tz);
 494                         if (r < 0)
 495                                 log_link_error_errno(link, r, "Failed to set timezone to '%s': %m", tz);
 496                 }
 497         }
 498
 499         if (!link->network->dhcp_critical) {
 500                 r = sd_dhcp_lease_get_lifetime(link->dhcp_lease, &lifetime);
 501                 if (r < 0)
 502                         return log_link_warning_errno(link, r, "DHCP error: no lifetime: %m");
 503         }
 504
 505         r = dhcp4_update_address(link, &address, &netmask, lifetime);
 506         if (r < 0) {
 507                 log_link_warning_errno(link, r, "Could not update IP address: %m");
 508                 link_enter_failed(link);
 509                 return r;
 510         }
 511
 512         return 0;
 513 }
 514
 515 static int dhcp_server_is_black_listed(Link *link, sd_dhcp_client *client) {
 516         sd_dhcp_lease *lease;
 517         struct in_addr addr;
 518         int r;
 519
 520         assert(link);
 521         assert(link->network);
 522         assert(client);
 523
 524         r = sd_dhcp_client_get_lease(client, &lease);
 525         if (r < 0)
 526                 return log_link_error_errno(link, r, "Failed to get DHCP lease: %m");
 527
 528         r = sd_dhcp_lease_get_server_identifier(lease, &addr);
 529         if (r < 0)
 530                 return log_link_debug_errno(link, r, "Failed to get DHCP server ip address: %m");
 531
 532         if (set_contains(link->network->dhcp_black_listed_ip, UINT32_TO_PTR(addr.s_addr))) {
 533                 log_struct(LOG_DEBUG,
 534                            LOG_LINK_INTERFACE(link),
 535                            LOG_LINK_MESSAGE(link, "DHCPv4 ip '%u.%u.%u.%u' found in black listed ip addresses, ignoring offer",
 536                                             ADDRESS_FMT_VAL(addr)));
 537                 return true;
 538         }
 539
 540         return false;
 541 }
 542
 543 static int dhcp4_handler(sd_dhcp_client *client, int event, void *userdata) {
 544         Link *link = userdata;
 545         int r = 0;
 546
 547         assert(link);
 548         assert(link->network);
 549         assert(link->manager);
 550
 551         if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
 552                 return 0;
 553
 554         switch (event) {
 555                 case SD_DHCP_CLIENT_EVENT_STOP:
 556
 557                         if (link_ipv4ll_fallback_enabled(link)) {
 558                                 assert(link->ipv4ll);
 559
 560                                 log_link_debug(link, "DHCP client is stopped. Acquiring IPv4 link-local address");
 561
 562                                 r = sd_ipv4ll_start(link->ipv4ll);
 563                                 if (r < 0)
 564                                         return log_link_warning_errno(link, r, "Could not acquire IPv4 link-local address: %m");
 565                         }
 566
 567                         _fallthrough_;
 568                 case SD_DHCP_CLIENT_EVENT_EXPIRED:
 569                 case SD_DHCP_CLIENT_EVENT_IP_CHANGE:
 570
 571                         if (link->network->dhcp_critical) {
 572                                 log_link_error(link, "DHCPv4 connection considered system critical, ignoring request to reconfigure it.");
 573                                 return 0;
 574                         }
 575
 576                         if (link->dhcp_lease) {
 577                                 r = dhcp_lease_lost(link);
 578                                 if (r < 0) {
 579                                         link_enter_failed(link);
 580                                         return r;
 581                                 }
 582                         }
 583
 584                         if (event == SD_DHCP_CLIENT_EVENT_IP_CHANGE) {
 585                                 r = dhcp_lease_acquired(client, link);
 586                                 if (r < 0) {
 587                                         link_enter_failed(link);
 588                                         return r;
 589                                 }
 590                         }
 591
 592                         break;
 593                 case SD_DHCP_CLIENT_EVENT_RENEW:
 594                         r = dhcp_lease_renew(client, link);
 595                         if (r < 0) {
 596                                 link_enter_failed(link);
 597                                 return r;
 598                         }
 599                         break;
 600                 case SD_DHCP_CLIENT_EVENT_IP_ACQUIRE:
 601                         r = dhcp_lease_acquired(client, link);
 602                         if (r < 0) {
 603                                 link_enter_failed(link);
 604                                 return r;
 605                         }
 606                         break;
 607                 case SD_DHCP_CLIENT_EVENT_SELECTING:
 608                         r = dhcp_server_is_black_listed(link, client);
 609                         if (r < 0)
 610                                 return r;
 611                         if (r != 0)
 612                                 return -ENOMSG;
 613                         break;
 614                 default:
 615                         if (event < 0)
 616                                 log_link_warning_errno(link, event, "DHCP error: Client failed: %m");
 617                         else
 618                                 log_link_warning(link, "DHCP unknown event: %i", event);
 619                         break;
 620         }
 621
 622         return 0;
 623 }
 624
 625 static int dhcp4_set_hostname(Link *link) {
 626         _cleanup_free_ char *hostname = NULL;
 627         const char *hn;
 628         int r;
 629
 630         assert(link);
 631
 632         if (!link->network->dhcp_send_hostname)
 633                 hn = NULL;
 634         else if (link->network->dhcp_hostname)
 635                 hn = link->network->dhcp_hostname;
 636         else {
 637                 r = gethostname_strict(&hostname);
 638                 if (r < 0 && r != -ENXIO) /* ENXIO: no hostname set or hostname is "localhost" */
 639                         return r;
 640
 641                 hn = hostname;
 642         }
 643
 644         r = sd_dhcp_client_set_hostname(link->dhcp_client, hn);
 645         if (r == -EINVAL && hostname)
 646                 /* Ignore error when the machine's hostname is not suitable to send in DHCP packet. */
 647                 log_link_warning_errno(link, r, "DHCP4 CLIENT: Failed to set hostname from kernel hostname, ignoring: %m");
 648         else if (r < 0)
 649                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set hostname: %m");
 650
 651         return 0;
 652 }
 653
 654 static bool promote_secondaries_enabled(const char *ifname) {
 655         _cleanup_free_ char *promote_secondaries_sysctl = NULL;
 656         char *promote_secondaries_path;
 657         int r;
 658
 659         promote_secondaries_path = strjoina("net/ipv4/conf/", ifname, "/promote_secondaries");
 660         r = sysctl_read(promote_secondaries_path, &promote_secondaries_sysctl);
 661         if (r < 0) {
 662                 log_debug_errno(r, "Cannot read sysctl %s", promote_secondaries_path);
 663                 return false;
 664         }
 665
 666         truncate_nl(promote_secondaries_sysctl);
 667         r = parse_boolean(promote_secondaries_sysctl);
 668         if (r < 0)
 669                 log_warning_errno(r, "Cannot parse sysctl %s with content %s as boolean", promote_secondaries_path, promote_secondaries_sysctl);
 670         return r > 0;
 671 }
 672
 673 /* dhcp4_set_promote_secondaries will ensure this interface has
 674  * the "promote_secondaries" option in the kernel set. If this sysctl
 675  * is not set DHCP will work only as long as the IP address does not
 676  * changes between leases. The kernel will remove all secondary IP
 677  * addresses of an interface otherwise. The way systemd-network works
 678  * is that the new IP of a lease is added as a secondary IP and when
 679  * the primary one expires it relies on the kernel to promote the
 680  * secondary IP. See also https://github.com/systemd/systemd/issues/7163
 681  */
 682 int dhcp4_set_promote_secondaries(Link *link) {
 683         int r;
 684
 685         assert(link);
 686         assert(link->network);
 687         assert(link->network->dhcp & ADDRESS_FAMILY_IPV4);
 688
 689         /* check if the kernel has promote_secondaries enabled for our
 690          * interface. If it is not globally enabled or enabled for the
 691          * specific interface we must either enable it.
 692          */
 693         if (!(promote_secondaries_enabled("all") || promote_secondaries_enabled(link->ifname))) {
 694                 char *promote_secondaries_path = NULL;
 695
 696                 log_link_debug(link, "promote_secondaries is unset, setting it");
 697                 promote_secondaries_path = strjoina("net/ipv4/conf/", link->ifname, "/promote_secondaries");
 698                 r = sysctl_write(promote_secondaries_path, "1");
 699                 if (r < 0)
 700                         log_link_warning_errno(link, r, "cannot set sysctl %s to 1", promote_secondaries_path);
 701                 return r > 0;
 702         }
 703
 704         return 0;
 705 }
 706
 707 int dhcp4_set_client_identifier(Link *link) {
 708         int r;
 709
 710         assert(link);
 711         assert(link->network);
 712         assert(link->dhcp_client);
 713
 714         switch (link->network->dhcp_client_identifier) {
 715         case DHCP_CLIENT_ID_DUID: {
 716                 /* If configured, apply user specified DUID and IAID */
 717                 const DUID *duid = link_get_duid(link);
 718
 719                 if (duid->type == DUID_TYPE_LLT && duid->raw_data_len == 0)
 720                         r = sd_dhcp_client_set_iaid_duid_llt(link->dhcp_client,
 721                                                              link->network->iaid_set,
 722                                                              link->network->iaid,
 723                                                              duid->llt_time);
 724                 else
 725                         r = sd_dhcp_client_set_iaid_duid(link->dhcp_client,
 726                                                          link->network->iaid_set,
 727                                                          link->network->iaid,
 728                                                          duid->type,
 729                                                          duid->raw_data_len > 0 ? duid->raw_data : NULL,
 730                                                          duid->raw_data_len);
 731                 if (r < 0)
 732                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set IAID+DUID: %m");
 733                 break;
 734         }
 735         case DHCP_CLIENT_ID_DUID_ONLY: {
 736                 /* If configured, apply user specified DUID */
 737                 const DUID *duid = link_get_duid(link);
 738
 739                 if (duid->type == DUID_TYPE_LLT && duid->raw_data_len == 0)
 740                         r = sd_dhcp_client_set_duid_llt(link->dhcp_client,
 741                                                         duid->llt_time);
 742                 else
 743                         r = sd_dhcp_client_set_duid(link->dhcp_client,
 744                                                     duid->type,
 745                                                     duid->raw_data_len > 0 ? duid->raw_data : NULL,
 746                                                     duid->raw_data_len);
 747                 if (r < 0)
 748                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set DUID: %m");
 749                 break;
 750         }
 751         case DHCP_CLIENT_ID_MAC:
 752                 r = sd_dhcp_client_set_client_id(link->dhcp_client,
 753                                                  ARPHRD_ETHER,
 754                                                  (const uint8_t *) &link->mac,
 755                                                  sizeof(link->mac));
 756                 if (r < 0)
 757                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set client ID: %m");
 758                 break;
 759         default:
 760                 assert_not_reached("Unknown client identifier type.");
 761         }
 762
 763         return 0;
 764 }
 765
 766 int dhcp4_configure(Link *link) {
 767         int r;
 768
 769         assert(link);
 770         assert(link->network);
 771         assert(link->network->dhcp & ADDRESS_FAMILY_IPV4);
 772
 773         if (!link->dhcp_client) {
 774                 r = sd_dhcp_client_new(&link->dhcp_client, link->network->dhcp_anonymize);
 775                 if (r == -ENOMEM)
 776                         return log_oom();
 777                 if (r < 0)
 778                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to create DHCP4 client: %m");
 779         }
 780
 781         r = sd_dhcp_client_attach_event(link->dhcp_client, NULL, 0);
 782         if (r < 0)
 783                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to attach event: %m");
 784
 785         r = sd_dhcp_client_set_mac(link->dhcp_client,
 786                                    (const uint8_t *) &link->mac,
 787                                    sizeof (link->mac), ARPHRD_ETHER);
 788         if (r < 0)
 789                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set MAC address: %m");
 790
 791         r = sd_dhcp_client_set_ifindex(link->dhcp_client, link->ifindex);
 792         if (r < 0)
 793                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set ifindex: %m");
 794
 795         r = sd_dhcp_client_set_callback(link->dhcp_client, dhcp4_handler, link);
 796         if (r < 0)
 797                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set callback: %m");
 798
 799         r = sd_dhcp_client_set_request_broadcast(link->dhcp_client,
 800                                                  link->network->dhcp_broadcast);
 801         if (r < 0)
 802                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for broadcast: %m");
 803
 804         if (link->mtu) {
 805                 r = sd_dhcp_client_set_mtu(link->dhcp_client, link->mtu);
 806                 if (r < 0)
 807                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set MTU: %m");
 808         }
 809
 810         if (link->network->dhcp_use_mtu) {
 811                 r = sd_dhcp_client_set_request_option(link->dhcp_client,
 812                                                       SD_DHCP_OPTION_INTERFACE_MTU);
 813                 if (r < 0)
 814                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for MTU: %m");
 815         }
 816
 817         /* NOTE: even if this variable is called "use", it also "sends" PRL
 818          * options, maybe there should be a different configuration variable
 819          * to send or not route options?. */
 820         /* NOTE: when using Anonymize=yes, routes PRL options are sent
 821          * by default, so they don't need to be added here. */
 822         if (link->network->dhcp_use_routes && !link->network->dhcp_anonymize) {
 823                 r = sd_dhcp_client_set_request_option(link->dhcp_client,
 824                                                       SD_DHCP_OPTION_STATIC_ROUTE);
 825                 if (r < 0)
 826                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for static route: %m");
 827
 828                 r = sd_dhcp_client_set_request_option(link->dhcp_client,
 829                                                       SD_DHCP_OPTION_CLASSLESS_STATIC_ROUTE);
 830                 if (r < 0)
 831                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for classless static route: %m");
 832         }
 833
 834         if (link->network->dhcp_use_ntp) {
 835                 r = sd_dhcp_client_set_request_option(link->dhcp_client, SD_DHCP_OPTION_NTP_SERVER);
 836                 if (r < 0)
 837                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for NTP server: %m");
 838         }
 839
 840         if (link->network->dhcp_use_timezone) {
 841                 r = sd_dhcp_client_set_request_option(link->dhcp_client, SD_DHCP_OPTION_NEW_TZDB_TIMEZONE);
 842                 if (r < 0)
 843                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for timezone: %m");
 844         }
 845
 846         r = dhcp4_set_hostname(link);
 847         if (r < 0)
 848                 return r;
 849
 850         if (link->network->dhcp_vendor_class_identifier) {
 851                 r = sd_dhcp_client_set_vendor_class_identifier(link->dhcp_client,
 852                                                                link->network->dhcp_vendor_class_identifier);
 853                 if (r < 0)
 854                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set vendor class identifier: %m");
 855         }
 856
 857         if (link->network->dhcp_user_class) {
 858                 r = sd_dhcp_client_set_user_class(link->dhcp_client, (const char **) link->network->dhcp_user_class);
 859                 if (r < 0)
 860                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set user class: %m");
 861         }
 862
 863         if (link->network->dhcp_client_port) {
 864                 r = sd_dhcp_client_set_client_port(link->dhcp_client, link->network->dhcp_client_port);
 865                 if (r < 0)
 866                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set listen port: %m");
 867         }
 868
 869         if (link->network->dhcp_max_attempts > 0) {
 870                 r = sd_dhcp_client_set_max_attempts(link->dhcp_client, link->network->dhcp_max_attempts);
 871                 if (r < 0)
 872                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set max attempts: %m");
 873         }
 874
 875         return dhcp4_set_client_identifier(link);
 876 }