src/resolve/resolved-dnssd.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include "sd-bus.h"
   4
   5 #include "alloc-util.h"
   6 #include "conf-files.h"
   7 #include "conf-parser.h"
   8 #include "constants.h"
   9 #include "dns-domain.h"
  10 #include "extract-word.h"
  11 #include "hashmap.h"
  12 #include "hexdecoct.h"
  13 #include "path-util.h"
  14 #include "resolved-conf.h"
  15 #include "resolved-dns-rr.h"
  16 #include "resolved-dns-zone.h"
  17 #include "resolved-dnssd.h"
  18 #include "resolved-manager.h"
  19 #include "specifier.h"
  20 #include "string-util.h"
  21 #include "strv.h"
  22 #include "utf8.h"
  23
  24 #define DNSSD_SERVICE_DIRS ((const char* const*) CONF_PATHS_STRV("systemd/dnssd"))
  25
  26 DnssdTxtData *dnssd_txtdata_free(DnssdTxtData *txt_data) {
  27         if (!txt_data)
  28                 return NULL;
  29
  30         dns_resource_record_unref(txt_data->rr);
  31         dns_txt_item_free_all(txt_data->txts);
  32
  33         return mfree(txt_data);
  34 }
  35
  36 DnssdTxtData *dnssd_txtdata_free_all(DnssdTxtData *txt_data) {
  37         DnssdTxtData *next;
  38
  39         if (!txt_data)
  40                 return NULL;
  41
  42         next = txt_data->items_next;
  43
  44         dnssd_txtdata_free(txt_data);
  45
  46         return dnssd_txtdata_free_all(next);
  47 }
  48
  49 DnssdService *dnssd_service_free(DnssdService *service) {
  50         if (!service)
  51                 return NULL;
  52
  53         if (service->manager)
  54                 hashmap_remove(service->manager->dnssd_services, service->id);
  55
  56         dns_resource_record_unref(service->ptr_rr);
  57         dns_resource_record_unref(service->sub_ptr_rr);
  58         dns_resource_record_unref(service->srv_rr);
  59
  60         dnssd_txtdata_free_all(service->txt_data_items);
  61
  62         free(service->path);
  63         free(service->id);
  64         free(service->type);
  65         free(service->subtype);
  66         free(service->name_template);
  67
  68         return mfree(service);
  69 }
  70
  71 void dnssd_service_clear_on_reload(Hashmap *services) {
  72         DnssdService *service;
  73
  74         HASHMAP_FOREACH(service, services)
  75                 if (service->config_source == RESOLVE_CONFIG_SOURCE_FILE) {
  76                         hashmap_remove(services, service->id);
  77                         dnssd_service_free(service);
  78                 }
  79 }
  80
  81 static int dnssd_id_from_path(const char *path, char **ret_id) {
  82         int r;
  83
  84         assert(path);
  85         assert(ret_id);
  86
  87         _cleanup_free_ char *fn = NULL;
  88         r = path_extract_filename(path, &fn);
  89         if (r < 0)
  90                 return r;
  91
  92         char *d = endswith(fn, ".dnssd");
  93         if (!d)
  94                 return -EINVAL;
  95
  96         *d = '\0';
  97
  98         *ret_id = TAKE_PTR(fn);
  99         return 0;
 100 }
 101
 102 static int dnssd_service_load(Manager *manager, const char *path) {
 103         _cleanup_(dnssd_service_freep) DnssdService *service = NULL;
 104         _cleanup_(dnssd_txtdata_freep) DnssdTxtData *txt_data = NULL;
 105         _cleanup_free_ char *dropin_dirname = NULL;
 106         int r;
 107
 108         assert(manager);
 109         assert(path);
 110
 111         service = new0(DnssdService, 1);
 112         if (!service)
 113                 return log_oom();
 114
 115         service->path = strdup(path);
 116         if (!service->path)
 117                 return log_oom();
 118
 119         r = dnssd_id_from_path(path, &service->id);
 120         if (r < 0)
 121                 return log_error_errno(r, "Failed to extract DNS-SD service id from filename: %m");
 122
 123         dropin_dirname = strjoin(service->id, ".dnssd.d");
 124         if (!dropin_dirname)
 125                 return log_oom();
 126
 127         r = config_parse_many(
 128                         STRV_MAKE_CONST(path), DNSSD_SERVICE_DIRS, dropin_dirname, /* root = */ NULL,
 129                         "Service\0",
 130                         config_item_perf_lookup, resolved_dnssd_gperf_lookup,
 131                         CONFIG_PARSE_WARN,
 132                         service,
 133                         NULL,
 134                         NULL);
 135         if (r < 0)
 136                 return r;
 137
 138         if (!service->name_template)
 139                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 140                                        "%s doesn't define service instance name",
 141                                        service->id);
 142
 143         if (!service->type)
 144                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 145                                        "%s doesn't define service type",
 146                                        service->id);
 147
 148         if (!service->txt_data_items) {
 149                 txt_data = new0(DnssdTxtData, 1);
 150                 if (!txt_data)
 151                         return log_oom();
 152
 153                 r = dns_txt_item_new_empty(&txt_data->txts);
 154                 if (r < 0)
 155                         return r;
 156
 157                 LIST_PREPEND(items, service->txt_data_items, txt_data);
 158                 TAKE_PTR(txt_data);
 159         }
 160
 161         r = hashmap_ensure_put(&manager->dnssd_services, &string_hash_ops, service->id, service);
 162         if (r < 0)
 163                 return r;
 164
 165         service->manager = manager;
 166
 167         r = dnssd_update_rrs(service);
 168         if (r < 0)
 169                 return r;
 170
 171         TAKE_PTR(service);
 172
 173         return 0;
 174 }
 175
 176 static int specifier_dnssd_hostname(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 177         const Manager *m = ASSERT_PTR(userdata);
 178
 179         assert(m->llmnr_hostname);
 180
 181         return strdup_to(ret, m->llmnr_hostname);
 182 }
 183
 184 int dnssd_render_instance_name(Manager *m, DnssdService *s, char **ret) {
 185         static const Specifier specifier_table[] = {
 186                 { 'a', specifier_architecture,   NULL },
 187                 { 'b', specifier_boot_id,        NULL },
 188                 { 'B', specifier_os_build_id,    NULL },
 189                 { 'H', specifier_dnssd_hostname, NULL },
 190                 { 'm', specifier_machine_id,     NULL },
 191                 { 'o', specifier_os_id,          NULL },
 192                 { 'v', specifier_kernel_release, NULL },
 193                 { 'w', specifier_os_version_id,  NULL },
 194                 { 'W', specifier_os_variant_id,  NULL },
 195                 {}
 196         };
 197         _cleanup_free_ char *name = NULL;
 198         int r;
 199
 200         assert(m);
 201         assert(s);
 202         assert(s->name_template);
 203
 204         r = specifier_printf(s->name_template, DNS_LABEL_MAX, specifier_table, NULL, m, &name);
 205         if (r < 0)
 206                 return log_debug_errno(r, "Failed to replace specifiers: %m");
 207
 208         if (!dns_service_name_is_valid(name))
 209                 return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
 210                                        "Service instance name '%s' is invalid.",
 211                                        name);
 212
 213         if (ret)
 214                 *ret = TAKE_PTR(name);
 215
 216         return 0;
 217 }
 218
 219 int dnssd_load(Manager *manager) {
 220         _cleanup_strv_free_ char **files = NULL;
 221         int r;
 222
 223         assert(manager);
 224
 225         if (manager->mdns_support != RESOLVE_SUPPORT_YES)
 226                 return 0;
 227
 228         r = conf_files_list_strv(&files, ".dnssd", NULL, 0, DNSSD_SERVICE_DIRS);
 229         if (r < 0)
 230                 return log_error_errno(r, "Failed to enumerate .dnssd files: %m");
 231
 232         STRV_FOREACH_BACKWARDS(f, files) {
 233                 r = dnssd_service_load(manager, *f);
 234                 if (r < 0)
 235                         log_warning_errno(r, "Failed to load '%s': %m", *f);
 236         }
 237
 238         return 0;
 239 }
 240
 241 int dnssd_update_rrs(DnssdService *s) {
 242         _cleanup_free_ char *n = NULL, *service_name = NULL, *full_name = NULL, *sub_name = NULL, *selective_name = NULL;
 243         int r;
 244
 245         assert(s);
 246         assert(s->txt_data_items);
 247         assert(s->manager);
 248
 249         s->ptr_rr = dns_resource_record_unref(s->ptr_rr);
 250         s->sub_ptr_rr = dns_resource_record_unref(s->sub_ptr_rr);
 251         s->srv_rr = dns_resource_record_unref(s->srv_rr);
 252         LIST_FOREACH(items, txt_data, s->txt_data_items)
 253                 txt_data->rr = dns_resource_record_unref(txt_data->rr);
 254
 255         r = dnssd_render_instance_name(s->manager, s, &n);
 256         if (r < 0)
 257                 return r;
 258
 259         r = dns_name_concat(s->type, "local", 0, &service_name);
 260         if (r < 0)
 261                 return r;
 262         r = dns_name_concat(n, service_name, 0, &full_name);
 263         if (r < 0)
 264                 return r;
 265         if (s->subtype) {
 266                 r = dns_name_concat("_sub", service_name, 0, &sub_name);
 267                 if (r < 0)
 268                         return r;
 269                 r = dns_name_concat(s->subtype, sub_name, 0, &selective_name);
 270                 if (r < 0)
 271                         return r;
 272         }
 273
 274         LIST_FOREACH(items, txt_data, s->txt_data_items) {
 275                 txt_data->rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_TXT,
 276                                                             full_name);
 277                 if (!txt_data->rr)
 278                         goto oom;
 279
 280                 txt_data->rr->ttl = MDNS_DEFAULT_TTL;
 281                 txt_data->rr->txt.items = dns_txt_item_copy(txt_data->txts);
 282                 if (!txt_data->rr->txt.items)
 283                         goto oom;
 284         }
 285
 286         s->ptr_rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR,
 287                                                  service_name);
 288         if (!s->ptr_rr)
 289                 goto oom;
 290
 291         s->ptr_rr->ttl = MDNS_DEFAULT_TTL;
 292         s->ptr_rr->ptr.name = strdup(full_name);
 293         if (!s->ptr_rr->ptr.name)
 294                 goto oom;
 295
 296         if (selective_name) {
 297                 s->sub_ptr_rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR, selective_name);
 298                 if (!s->sub_ptr_rr)
 299                         goto oom;
 300
 301                 s->sub_ptr_rr->ttl = MDNS_DEFAULT_TTL;
 302                 s->sub_ptr_rr->ptr.name = strdup(full_name);
 303                 if (!s->sub_ptr_rr->ptr.name)
 304                         goto oom;
 305         }
 306
 307         s->srv_rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_SRV,
 308                                                  full_name);
 309         if (!s->srv_rr)
 310                 goto oom;
 311
 312         s->srv_rr->ttl = MDNS_DEFAULT_TTL;
 313         s->srv_rr->srv.priority = s->priority;
 314         s->srv_rr->srv.weight = s->weight;
 315         s->srv_rr->srv.port = s->port;
 316         s->srv_rr->srv.name = strdup(s->manager->mdns_hostname);
 317         if (!s->srv_rr->srv.name)
 318                 goto oom;
 319
 320         return 0;
 321
 322 oom:
 323         LIST_FOREACH(items, txt_data, s->txt_data_items)
 324                 txt_data->rr = dns_resource_record_unref(txt_data->rr);
 325         s->ptr_rr = dns_resource_record_unref(s->ptr_rr);
 326         s->sub_ptr_rr = dns_resource_record_unref(s->sub_ptr_rr);
 327         s->srv_rr = dns_resource_record_unref(s->srv_rr);
 328         return -ENOMEM;
 329 }
 330
 331 int dnssd_txt_item_new_from_string(const char *key, const char *value, DnsTxtItem **ret_item) {
 332         size_t length;
 333         DnsTxtItem *i;
 334
 335         length = strlen(key);
 336
 337         if (!isempty(value))
 338                 length += strlen(value) + 1; /* length of value plus '=' */
 339
 340         i = malloc0(offsetof(DnsTxtItem, data) + length + 1); /* for safety reasons we add an extra NUL byte */
 341         if (!i)
 342                 return -ENOMEM;
 343
 344         memcpy(i->data, key, strlen(key));
 345         if (!isempty(value)) {
 346                 memcpy(i->data + strlen(key), "=", 1);
 347                 memcpy(i->data + strlen(key) + 1, value, strlen(value));
 348         }
 349         i->length = length;
 350
 351         *ret_item = TAKE_PTR(i);
 352
 353         return 0;
 354 }
 355
 356 int dnssd_txt_item_new_from_data(const char *key, const void *data, const size_t size, DnsTxtItem **ret_item) {
 357         size_t length;
 358         DnsTxtItem *i;
 359
 360         length = strlen(key);
 361
 362         if (size > 0)
 363                 length += size + 1; /* size of date plus '=' */
 364
 365         i = malloc0(offsetof(DnsTxtItem, data) + length + 1); /* for safety reasons we add an extra NUL byte */
 366         if (!i)
 367                 return -ENOMEM;
 368
 369         memcpy(i->data, key, strlen(key));
 370         if (size > 0) {
 371                 memcpy(i->data + strlen(key), "=", 1);
 372                 memcpy(i->data + strlen(key) + 1, data, size);
 373         }
 374         i->length = length;
 375
 376         *ret_item = TAKE_PTR(i);
 377
 378         return 0;
 379 }
 380
 381 int dnssd_signal_conflict(Manager *manager, const char *name) {
 382         DnssdService *s;
 383         int r;
 384
 385         if (sd_bus_is_ready(manager->bus) <= 0)
 386                 return 0;
 387
 388         HASHMAP_FOREACH(s, manager->dnssd_services) {
 389                 if (s->withdrawn)
 390                         continue;
 391
 392                 if (dns_name_equal(dns_resource_key_name(s->srv_rr->key), name) > 0) {
 393                         _cleanup_free_ char *path = NULL;
 394
 395                         s->withdrawn = true;
 396
 397                         r = sd_bus_path_encode("/org/freedesktop/resolve1/dnssd", s->id, &path);
 398                         if (r < 0)
 399                                 return log_error_errno(r, "Can't get D-BUS object path: %m");
 400
 401                         r = sd_bus_emit_signal(manager->bus,
 402                                                path,
 403                                                "org.freedesktop.resolve1.DnssdService",
 404                                                "Conflicted",
 405                                                NULL);
 406                         if (r < 0)
 407                                 return log_error_errno(r, "Cannot emit signal: %m");
 408
 409                         break;
 410                 }
 411         }
 412
 413         return 0;
 414 }
 415
 416 int config_parse_dnssd_service_name(
 417                 const char *unit,
 418                 const char *filename,
 419                 unsigned line,
 420                 const char *section,
 421                 unsigned section_line,
 422                 const char *lvalue,
 423                 int ltype,
 424                 const char *rvalue,
 425                 void *data,
 426                 void *userdata) {
 427
 428         static const Specifier specifier_table[] = {
 429                 { 'a', specifier_architecture,    NULL },
 430                 { 'b', specifier_boot_id,         NULL },
 431                 { 'B', specifier_os_build_id,     NULL },
 432                 { 'H', specifier_hostname,        NULL }, /* We will use specifier_dnssd_hostname(). */
 433                 { 'm', specifier_machine_id,      NULL },
 434                 { 'o', specifier_os_id,           NULL },
 435                 { 'v', specifier_kernel_release,  NULL },
 436                 { 'w', specifier_os_version_id,   NULL },
 437                 { 'W', specifier_os_variant_id,   NULL },
 438                 {}
 439         };
 440         DnssdService *s = ASSERT_PTR(userdata);
 441         _cleanup_free_ char *name = NULL;
 442         int r;
 443
 444         assert(filename);
 445         assert(lvalue);
 446         assert(rvalue);
 447
 448         if (isempty(rvalue)) {
 449                 s->name_template = mfree(s->name_template);
 450                 return 0;
 451         }
 452
 453         r = specifier_printf(rvalue, DNS_LABEL_MAX, specifier_table, NULL, NULL, &name);
 454         if (r < 0) {
 455                 log_syntax(unit, LOG_WARNING, filename, line, r,
 456                            "Invalid service instance name template '%s', ignoring assignment: %m", rvalue);
 457                 return 0;
 458         }
 459
 460         if (!dns_service_name_is_valid(name)) {
 461                 log_syntax(unit, LOG_WARNING, filename, line, 0,
 462                            "Service instance name template '%s' renders to invalid name '%s'. Ignoring assignment.",
 463                            rvalue, name);
 464                 return 0;
 465         }
 466
 467         return free_and_strdup_warn(&s->name_template, rvalue);
 468 }
 469
 470 int config_parse_dnssd_service_type(
 471                 const char *unit,
 472                 const char *filename,
 473                 unsigned line,
 474                 const char *section,
 475                 unsigned section_line,
 476                 const char *lvalue,
 477                 int ltype,
 478                 const char *rvalue,
 479                 void *data,
 480                 void *userdata) {
 481
 482         DnssdService *s = ASSERT_PTR(userdata);
 483         int r;
 484
 485         assert(filename);
 486         assert(lvalue);
 487         assert(rvalue);
 488
 489         if (isempty(rvalue)) {
 490                 s->type = mfree(s->type);
 491                 return 0;
 492         }
 493
 494         if (!dnssd_srv_type_is_valid(rvalue)) {
 495                 log_syntax(unit, LOG_WARNING, filename, line, 0, "Service type is invalid. Ignoring.");
 496                 return 0;
 497         }
 498
 499         r = free_and_strdup(&s->type, rvalue);
 500         if (r < 0)
 501                 return log_oom();
 502
 503         return 0;
 504 }
 505
 506 int config_parse_dnssd_service_subtype(
 507                 const char *unit,
 508                 const char *filename,
 509                 unsigned line,
 510                 const char *section,
 511                 unsigned section_line,
 512                 const char *lvalue,
 513                 int ltype,
 514                 const char *rvalue,
 515                 void *data,
 516                 void *userdata) {
 517
 518         DnssdService *s = ASSERT_PTR(userdata);
 519
 520         assert(filename);
 521         assert(lvalue);
 522         assert(rvalue);
 523
 524         if (isempty(rvalue)) {
 525                 s->subtype = mfree(s->subtype);
 526                 return 0;
 527         }
 528
 529         if (!dns_subtype_name_is_valid(rvalue)) {
 530                 log_syntax(unit, LOG_WARNING, filename, line, 0, "Service subtype is invalid. Ignoring.");
 531                 return 0;
 532         }
 533
 534         return free_and_strdup_warn(&s->subtype, rvalue);
 535 }
 536
 537 int config_parse_dnssd_txt(
 538                 const char *unit,
 539                 const char *filename,
 540                 unsigned line,
 541                 const char *section,
 542                 unsigned section_line,
 543                 const char *lvalue,
 544                 int ltype,
 545                 const char *rvalue,
 546                 void *data,
 547                 void *userdata) {
 548
 549         _cleanup_(dnssd_txtdata_freep) DnssdTxtData *txt_data = NULL;
 550         DnssdService *s = ASSERT_PTR(userdata);
 551         DnsTxtItem *last = NULL;
 552
 553         assert(filename);
 554         assert(lvalue);
 555         assert(rvalue);
 556
 557         if (isempty(rvalue)) {
 558                 /* Flush out collected items */
 559                 s->txt_data_items = dnssd_txtdata_free_all(s->txt_data_items);
 560                 return 0;
 561         }
 562
 563         txt_data = new0(DnssdTxtData, 1);
 564         if (!txt_data)
 565                 return log_oom();
 566
 567         for (;;) {
 568                 _cleanup_free_ char *word = NULL, *key = NULL, *value = NULL;
 569                 _cleanup_free_ void *decoded = NULL;
 570                 size_t length = 0;
 571                 DnsTxtItem *i;
 572                 int r;
 573
 574                 r = extract_first_word(&rvalue, &word, NULL,
 575                                        EXTRACT_UNQUOTE|EXTRACT_CUNESCAPE|EXTRACT_UNESCAPE_RELAX);
 576                 if (r == 0)
 577                         break;
 578                 if (r == -ENOMEM)
 579                         return log_oom();
 580                 if (r < 0) {
 581                         log_syntax(unit, LOG_WARNING, filename, line, r, "Invalid syntax, ignoring: %s", rvalue);
 582                         return 0;
 583                 }
 584
 585                 r = split_pair(word, "=", &key, &value);
 586                 if (r == -ENOMEM)
 587                         return log_oom();
 588                 if (r == -EINVAL)
 589                         key = TAKE_PTR(word);
 590
 591                 if (!ascii_is_valid(key)) {
 592                         log_syntax(unit, LOG_WARNING, filename, line, 0, "Invalid key, ignoring: %s", key);
 593                         continue;
 594                 }
 595
 596                 switch (ltype) {
 597
 598                 case DNS_TXT_ITEM_DATA:
 599                         if (value) {
 600                                 r = unbase64mem(value, &decoded, &length);
 601                                 if (r == -ENOMEM)
 602                                         return log_oom();
 603                                 if (r < 0) {
 604                                         log_syntax(unit, LOG_WARNING, filename, line, r,
 605                                                    "Invalid base64 encoding, ignoring: %s", value);
 606                                         continue;
 607                                 }
 608                         }
 609
 610                         r = dnssd_txt_item_new_from_data(key, decoded, length, &i);
 611                         if (r < 0)
 612                                 return log_oom();
 613                         break;
 614
 615                 case DNS_TXT_ITEM_TEXT:
 616                         r = dnssd_txt_item_new_from_string(key, value, &i);
 617                         if (r < 0)
 618                                 return log_oom();
 619                         break;
 620
 621                 default:
 622                         assert_not_reached();
 623                 }
 624
 625                 LIST_INSERT_AFTER(items, txt_data->txts, last, i);
 626                 last = i;
 627         }
 628
 629         if (txt_data->txts) {
 630                 LIST_PREPEND(items, s->txt_data_items, txt_data);
 631                 TAKE_PTR(txt_data);
 632         }
 633
 634         return 0;
 635 }