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 void dhcp4_handler(sd_dhcp_client *client, int event, void *userdata) {
 516         Link *link = userdata;
 517         int r = 0;
 518
 519         assert(link);
 520         assert(link->network);
 521         assert(link->manager);
 522
 523         if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
 524                 return;
 525
 526         switch (event) {
 527                 case SD_DHCP_CLIENT_EVENT_STOP:
 528
 529                         if (link_ipv4ll_fallback_enabled(link)) {
 530                                 assert(link->ipv4ll);
 531
 532                                 log_link_debug(link, "DHCP client is stopped. Acquiring IPv4 link-local address");
 533
 534                                 r = sd_ipv4ll_start(link->ipv4ll);
 535                                 if (r < 0) {
 536                                         log_link_warning_errno(link, r, "Could not acquire IPv4 link-local address: %m");
 537                                         return;
 538                                 }
 539                         }
 540
 541                         _fallthrough_;
 542                 case SD_DHCP_CLIENT_EVENT_EXPIRED:
 543                 case SD_DHCP_CLIENT_EVENT_IP_CHANGE:
 544
 545                         if (link->network->dhcp_critical) {
 546                                 log_link_error(link, "DHCPv4 connection considered system critical, ignoring request to reconfigure it.");
 547                                 return;
 548                         }
 549
 550                         if (link->dhcp_lease) {
 551                                 r = dhcp_lease_lost(link);
 552                                 if (r < 0) {
 553                                         link_enter_failed(link);
 554                                         return;
 555                                 }
 556                         }
 557
 558                         if (event == SD_DHCP_CLIENT_EVENT_IP_CHANGE) {
 559                                 r = dhcp_lease_acquired(client, link);
 560                                 if (r < 0) {
 561                                         link_enter_failed(link);
 562                                         return;
 563                                 }
 564                         }
 565
 566                         break;
 567                 case SD_DHCP_CLIENT_EVENT_RENEW:
 568                         r = dhcp_lease_renew(client, link);
 569                         if (r < 0) {
 570                                 link_enter_failed(link);
 571                                 return;
 572                         }
 573                         break;
 574                 case SD_DHCP_CLIENT_EVENT_IP_ACQUIRE:
 575                         r = dhcp_lease_acquired(client, link);
 576                         if (r < 0) {
 577                                 link_enter_failed(link);
 578                                 return;
 579                         }
 580                         break;
 581                 default:
 582                         if (event < 0)
 583                                 log_link_warning_errno(link, event, "DHCP error: Client failed: %m");
 584                         else
 585                                 log_link_warning(link, "DHCP unknown event: %i", event);
 586                         break;
 587         }
 588
 589         return;
 590 }
 591
 592 static int dhcp4_set_hostname(Link *link) {
 593         _cleanup_free_ char *hostname = NULL;
 594         const char *hn;
 595         int r;
 596
 597         assert(link);
 598
 599         if (!link->network->dhcp_send_hostname)
 600                 hn = NULL;
 601         else if (link->network->dhcp_hostname)
 602                 hn = link->network->dhcp_hostname;
 603         else {
 604                 r = gethostname_strict(&hostname);
 605                 if (r < 0 && r != -ENXIO) /* ENXIO: no hostname set or hostname is "localhost" */
 606                         return r;
 607
 608                 hn = hostname;
 609         }
 610
 611         r = sd_dhcp_client_set_hostname(link->dhcp_client, hn);
 612         if (r == -EINVAL && hostname)
 613                 /* Ignore error when the machine's hostname is not suitable to send in DHCP packet. */
 614                 log_link_warning_errno(link, r, "DHCP4 CLIENT: Failed to set hostname from kernel hostname, ignoring: %m");
 615         else if (r < 0)
 616                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set hostname: %m");
 617
 618         return 0;
 619 }
 620
 621 static bool promote_secondaries_enabled(const char *ifname) {
 622         _cleanup_free_ char *promote_secondaries_sysctl = NULL;
 623         char *promote_secondaries_path;
 624         int r;
 625
 626         promote_secondaries_path = strjoina("net/ipv4/conf/", ifname, "/promote_secondaries");
 627         r = sysctl_read(promote_secondaries_path, &promote_secondaries_sysctl);
 628         if (r < 0) {
 629                 log_debug_errno(r, "Cannot read sysctl %s", promote_secondaries_path);
 630                 return false;
 631         }
 632
 633         truncate_nl(promote_secondaries_sysctl);
 634         r = parse_boolean(promote_secondaries_sysctl);
 635         if (r < 0)
 636                 log_warning_errno(r, "Cannot parse sysctl %s with content %s as boolean", promote_secondaries_path, promote_secondaries_sysctl);
 637         return r > 0;
 638 }
 639
 640 /* dhcp4_set_promote_secondaries will ensure this interface has
 641  * the "promote_secondaries" option in the kernel set. If this sysctl
 642  * is not set DHCP will work only as long as the IP address does not
 643  * changes between leases. The kernel will remove all secondary IP
 644  * addresses of an interface otherwise. The way systemd-network works
 645  * is that the new IP of a lease is added as a secondary IP and when
 646  * the primary one expires it relies on the kernel to promote the
 647  * secondary IP. See also https://github.com/systemd/systemd/issues/7163
 648  */
 649 int dhcp4_set_promote_secondaries(Link *link) {
 650         int r;
 651
 652         assert(link);
 653         assert(link->network);
 654         assert(link->network->dhcp & ADDRESS_FAMILY_IPV4);
 655
 656         /* check if the kernel has promote_secondaries enabled for our
 657          * interface. If it is not globally enabled or enabled for the
 658          * specific interface we must either enable it.
 659          */
 660         if (!(promote_secondaries_enabled("all") || promote_secondaries_enabled(link->ifname))) {
 661                 char *promote_secondaries_path = NULL;
 662
 663                 log_link_debug(link, "promote_secondaries is unset, setting it");
 664                 promote_secondaries_path = strjoina("net/ipv4/conf/", link->ifname, "/promote_secondaries");
 665                 r = sysctl_write(promote_secondaries_path, "1");
 666                 if (r < 0)
 667                         log_link_warning_errno(link, r, "cannot set sysctl %s to 1", promote_secondaries_path);
 668                 return r > 0;
 669         }
 670
 671         return 0;
 672 }
 673
 674 int dhcp4_set_client_identifier(Link *link) {
 675         int r;
 676
 677         assert(link);
 678         assert(link->network);
 679         assert(link->dhcp_client);
 680
 681         switch (link->network->dhcp_client_identifier) {
 682         case DHCP_CLIENT_ID_DUID: {
 683                 /* If configured, apply user specified DUID and IAID */
 684                 const DUID *duid = link_get_duid(link);
 685
 686                 if (duid->type == DUID_TYPE_LLT && duid->raw_data_len == 0)
 687                         r = sd_dhcp_client_set_iaid_duid_llt(link->dhcp_client,
 688                                                              link->network->iaid_set,
 689                                                              link->network->iaid,
 690                                                              duid->llt_time);
 691                 else
 692                         r = sd_dhcp_client_set_iaid_duid(link->dhcp_client,
 693                                                          link->network->iaid_set,
 694                                                          link->network->iaid,
 695                                                          duid->type,
 696                                                          duid->raw_data_len > 0 ? duid->raw_data : NULL,
 697                                                          duid->raw_data_len);
 698                 if (r < 0)
 699                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set IAID+DUID: %m");
 700                 break;
 701         }
 702         case DHCP_CLIENT_ID_DUID_ONLY: {
 703                 /* If configured, apply user specified DUID */
 704                 const DUID *duid = link_get_duid(link);
 705
 706                 if (duid->type == DUID_TYPE_LLT && duid->raw_data_len == 0)
 707                         r = sd_dhcp_client_set_duid_llt(link->dhcp_client,
 708                                                         duid->llt_time);
 709                 else
 710                         r = sd_dhcp_client_set_duid(link->dhcp_client,
 711                                                     duid->type,
 712                                                     duid->raw_data_len > 0 ? duid->raw_data : NULL,
 713                                                     duid->raw_data_len);
 714                 if (r < 0)
 715                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set DUID: %m");
 716                 break;
 717         }
 718         case DHCP_CLIENT_ID_MAC:
 719                 r = sd_dhcp_client_set_client_id(link->dhcp_client,
 720                                                  ARPHRD_ETHER,
 721                                                  (const uint8_t *) &link->mac,
 722                                                  sizeof(link->mac));
 723                 if (r < 0)
 724                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set client ID: %m");
 725                 break;
 726         default:
 727                 assert_not_reached("Unknown client identifier type.");
 728         }
 729
 730         return 0;
 731 }
 732
 733 int dhcp4_configure(Link *link) {
 734         int r;
 735
 736         assert(link);
 737         assert(link->network);
 738         assert(link->network->dhcp & ADDRESS_FAMILY_IPV4);
 739
 740         if (!link->dhcp_client) {
 741                 r = sd_dhcp_client_new(&link->dhcp_client, link->network->dhcp_anonymize);
 742                 if (r == -ENOMEM)
 743                         return log_oom();
 744                 if (r < 0)
 745                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to create DHCP4 client: %m");
 746         }
 747
 748         r = sd_dhcp_client_attach_event(link->dhcp_client, NULL, 0);
 749         if (r < 0)
 750                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to attach event: %m");
 751
 752         r = sd_dhcp_client_set_mac(link->dhcp_client,
 753                                    (const uint8_t *) &link->mac,
 754                                    sizeof (link->mac), ARPHRD_ETHER);
 755         if (r < 0)
 756                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set MAC address: %m");
 757
 758         r = sd_dhcp_client_set_ifindex(link->dhcp_client, link->ifindex);
 759         if (r < 0)
 760                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set ifindex: %m");
 761
 762         r = sd_dhcp_client_set_callback(link->dhcp_client, dhcp4_handler, link);
 763         if (r < 0)
 764                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set callback: %m");
 765
 766         r = sd_dhcp_client_set_request_broadcast(link->dhcp_client,
 767                                                  link->network->dhcp_broadcast);
 768         if (r < 0)
 769                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for broadcast: %m");
 770
 771         if (link->mtu) {
 772                 r = sd_dhcp_client_set_mtu(link->dhcp_client, link->mtu);
 773                 if (r < 0)
 774                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set MTU: %m");
 775         }
 776
 777         if (link->network->dhcp_use_mtu) {
 778                 r = sd_dhcp_client_set_request_option(link->dhcp_client,
 779                                                       SD_DHCP_OPTION_INTERFACE_MTU);
 780                 if (r < 0)
 781                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for MTU: %m");
 782         }
 783
 784         /* NOTE: even if this variable is called "use", it also "sends" PRL
 785          * options, maybe there should be a different configuration variable
 786          * to send or not route options?. */
 787         /* NOTE: when using Anonymize=yes, routes PRL options are sent
 788          * by default, so they don't need to be added here. */
 789         if (link->network->dhcp_use_routes && !link->network->dhcp_anonymize) {
 790                 r = sd_dhcp_client_set_request_option(link->dhcp_client,
 791                                                       SD_DHCP_OPTION_STATIC_ROUTE);
 792                 if (r < 0)
 793                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for static route: %m");
 794
 795                 r = sd_dhcp_client_set_request_option(link->dhcp_client,
 796                                                       SD_DHCP_OPTION_CLASSLESS_STATIC_ROUTE);
 797                 if (r < 0)
 798                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for classless static route: %m");
 799         }
 800
 801         if (link->network->dhcp_use_ntp) {
 802                 r = sd_dhcp_client_set_request_option(link->dhcp_client, SD_DHCP_OPTION_NTP_SERVER);
 803                 if (r < 0)
 804                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for NTP server: %m");
 805         }
 806
 807         if (link->network->dhcp_use_timezone) {
 808                 r = sd_dhcp_client_set_request_option(link->dhcp_client, SD_DHCP_OPTION_NEW_TZDB_TIMEZONE);
 809                 if (r < 0)
 810                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set request flag for timezone: %m");
 811         }
 812
 813         r = dhcp4_set_hostname(link);
 814         if (r < 0)
 815                 return r;
 816
 817         if (link->network->dhcp_vendor_class_identifier) {
 818                 r = sd_dhcp_client_set_vendor_class_identifier(link->dhcp_client,
 819                                                                link->network->dhcp_vendor_class_identifier);
 820                 if (r < 0)
 821                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set vendor class identifier: %m");
 822         }
 823
 824         if (link->network->dhcp_user_class) {
 825                 r = sd_dhcp_client_set_user_class(link->dhcp_client, (const char **) link->network->dhcp_user_class);
 826                 if (r < 0)
 827                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set user class: %m");
 828         }
 829
 830         if (link->network->dhcp_client_port) {
 831                 r = sd_dhcp_client_set_client_port(link->dhcp_client, link->network->dhcp_client_port);
 832                 if (r < 0)
 833                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set listen port: %m");
 834         }
 835
 836         if (link->network->dhcp_max_attempts > 0) {
 837                 r = sd_dhcp_client_set_max_attempts(link->dhcp_client, link->network->dhcp_max_attempts);
 838                 if (r < 0)
 839                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set max attempts: %m");
 840         }
 841
 842         return dhcp4_set_client_identifier(link);
 843 }