src/resolve/resolved-dnssd.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include "conf-files.h"
   4 #include "conf-parser.h"
   5 #include "constants.h"
   6 #include "resolved-dnssd.h"
   7 #include "resolved-dns-rr.h"
   8 #include "resolved-manager.h"
   9 #include "resolved-conf.h"
  10 #include "specifier.h"
  11 #include "strv.h"
  12
  13 #define DNSSD_SERVICE_DIRS ((const char* const*) CONF_PATHS_STRV("systemd/dnssd"))
  14
  15 DnssdTxtData *dnssd_txtdata_free(DnssdTxtData *txt_data) {
  16         if (!txt_data)
  17                 return NULL;
  18
  19         dns_resource_record_unref(txt_data->rr);
  20         dns_txt_item_free_all(txt_data->txts);
  21
  22         return mfree(txt_data);
  23 }
  24
  25 DnssdTxtData *dnssd_txtdata_free_all(DnssdTxtData *txt_data) {
  26         DnssdTxtData *next;
  27
  28         if (!txt_data)
  29                 return NULL;
  30
  31         next = txt_data->items_next;
  32
  33         dnssd_txtdata_free(txt_data);
  34
  35         return dnssd_txtdata_free_all(next);
  36 }
  37
  38 DnssdService *dnssd_service_free(DnssdService *service) {
  39         if (!service)
  40                 return NULL;
  41
  42         if (service->manager)
  43                 hashmap_remove(service->manager->dnssd_services, service->name);
  44
  45         dns_resource_record_unref(service->ptr_rr);
  46         dns_resource_record_unref(service->srv_rr);
  47
  48         dnssd_txtdata_free_all(service->txt_data_items);
  49
  50         free(service->filename);
  51         free(service->name);
  52         free(service->type);
  53         free(service->name_template);
  54
  55         return mfree(service);
  56 }
  57
  58 static int dnssd_service_load(Manager *manager, const char *filename) {
  59         _cleanup_(dnssd_service_freep) DnssdService *service = NULL;
  60         _cleanup_(dnssd_txtdata_freep) DnssdTxtData *txt_data = NULL;
  61         char *d;
  62         const char *dropin_dirname;
  63         int r;
  64
  65         assert(manager);
  66         assert(filename);
  67
  68         service = new0(DnssdService, 1);
  69         if (!service)
  70                 return log_oom();
  71
  72         service->filename = strdup(filename);
  73         if (!service->filename)
  74                 return log_oom();
  75
  76         service->name = strdup(basename(filename));
  77         if (!service->name)
  78                 return log_oom();
  79
  80         d = endswith(service->name, ".dnssd");
  81         if (!d)
  82                 return -EINVAL;
  83
  84         assert(streq(d, ".dnssd"));
  85
  86         *d = '\0';
  87
  88         dropin_dirname = strjoina(service->name, ".dnssd.d");
  89
  90         r = config_parse_many(
  91                         STRV_MAKE_CONST(filename), DNSSD_SERVICE_DIRS, dropin_dirname, /* root = */ NULL,
  92                         "Service\0",
  93                         config_item_perf_lookup, resolved_dnssd_gperf_lookup,
  94                         CONFIG_PARSE_WARN,
  95                         service,
  96                         NULL,
  97                         NULL);
  98         if (r < 0)
  99                 return r;
 100
 101         if (!service->name_template)
 102                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 103                                        "%s doesn't define service instance name",
 104                                        service->name);
 105
 106         if (!service->type)
 107                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 108                                        "%s doesn't define service type",
 109                                        service->name);
 110
 111         if (!service->txt_data_items) {
 112                 txt_data = new0(DnssdTxtData, 1);
 113                 if (!txt_data)
 114                         return log_oom();
 115
 116                 r = dns_txt_item_new_empty(&txt_data->txts);
 117                 if (r < 0)
 118                         return r;
 119
 120                 LIST_PREPEND(items, service->txt_data_items, txt_data);
 121                 TAKE_PTR(txt_data);
 122         }
 123
 124         r = hashmap_ensure_put(&manager->dnssd_services, &string_hash_ops, service->name, service);
 125         if (r < 0)
 126                 return r;
 127
 128         service->manager = manager;
 129
 130         r = dnssd_update_rrs(service);
 131         if (r < 0)
 132                 return r;
 133
 134         TAKE_PTR(service);
 135
 136         return 0;
 137 }
 138
 139 static int specifier_dnssd_hostname(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 140         const Manager *m = ASSERT_PTR(userdata);
 141         char *n;
 142
 143         assert(m->llmnr_hostname);
 144
 145         n = strdup(m->llmnr_hostname);
 146         if (!n)
 147                 return -ENOMEM;
 148
 149         *ret = n;
 150         return 0;
 151 }
 152
 153 int dnssd_render_instance_name(Manager *m, DnssdService *s, char **ret) {
 154         static const Specifier specifier_table[] = {
 155                 { 'a', specifier_architecture,   NULL },
 156                 { 'b', specifier_boot_id,        NULL },
 157                 { 'B', specifier_os_build_id,    NULL },
 158                 { 'H', specifier_dnssd_hostname, NULL },
 159                 { 'm', specifier_machine_id,     NULL },
 160                 { 'o', specifier_os_id,          NULL },
 161                 { 'v', specifier_kernel_release, NULL },
 162                 { 'w', specifier_os_version_id,  NULL },
 163                 { 'W', specifier_os_variant_id,  NULL },
 164                 {}
 165         };
 166         _cleanup_free_ char *name = NULL;
 167         int r;
 168
 169         assert(m);
 170         assert(s);
 171         assert(s->name_template);
 172
 173         r = specifier_printf(s->name_template, DNS_LABEL_MAX, specifier_table, NULL, m, &name);
 174         if (r < 0)
 175                 return log_debug_errno(r, "Failed to replace specifiers: %m");
 176
 177         if (!dns_service_name_is_valid(name))
 178                 return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
 179                                        "Service instance name '%s' is invalid.",
 180                                        name);
 181
 182         if (ret)
 183                 *ret = TAKE_PTR(name);
 184
 185         return 0;
 186 }
 187
 188 int dnssd_load(Manager *manager) {
 189         _cleanup_strv_free_ char **files = NULL;
 190         int r;
 191
 192         assert(manager);
 193
 194         if (manager->mdns_support != RESOLVE_SUPPORT_YES)
 195                 return 0;
 196
 197         r = conf_files_list_strv(&files, ".dnssd", NULL, 0, DNSSD_SERVICE_DIRS);
 198         if (r < 0)
 199                 return log_error_errno(r, "Failed to enumerate .dnssd files: %m");
 200
 201         STRV_FOREACH_BACKWARDS(f, files) {
 202                 r = dnssd_service_load(manager, *f);
 203                 if (r < 0)
 204                         log_warning_errno(r, "Failed to load '%s': %m", *f);
 205         }
 206
 207         return 0;
 208 }
 209
 210 int dnssd_update_rrs(DnssdService *s) {
 211         _cleanup_free_ char *n = NULL, *service_name = NULL, *full_name = NULL;
 212         int r;
 213
 214         assert(s);
 215         assert(s->txt_data_items);
 216         assert(s->manager);
 217
 218         s->ptr_rr = dns_resource_record_unref(s->ptr_rr);
 219         s->srv_rr = dns_resource_record_unref(s->srv_rr);
 220         LIST_FOREACH(items, txt_data, s->txt_data_items)
 221                 txt_data->rr = dns_resource_record_unref(txt_data->rr);
 222
 223         r = dnssd_render_instance_name(s->manager, s, &n);
 224         if (r < 0)
 225                 return r;
 226
 227         r = dns_name_concat(s->type, "local", 0, &service_name);
 228         if (r < 0)
 229                 return r;
 230         r = dns_name_concat(n, service_name, 0, &full_name);
 231         if (r < 0)
 232                 return r;
 233
 234         LIST_FOREACH(items, txt_data, s->txt_data_items) {
 235                 txt_data->rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_TXT,
 236                                                             full_name);
 237                 if (!txt_data->rr)
 238                         goto oom;
 239
 240                 txt_data->rr->ttl = MDNS_DEFAULT_TTL;
 241                 txt_data->rr->txt.items = dns_txt_item_copy(txt_data->txts);
 242                 if (!txt_data->rr->txt.items)
 243                         goto oom;
 244         }
 245
 246         s->ptr_rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR,
 247                                                  service_name);
 248         if (!s->ptr_rr)
 249                 goto oom;
 250
 251         s->ptr_rr->ttl = MDNS_DEFAULT_TTL;
 252         s->ptr_rr->ptr.name = strdup(full_name);
 253         if (!s->ptr_rr->ptr.name)
 254                 goto oom;
 255
 256         s->srv_rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_SRV,
 257                                                  full_name);
 258         if (!s->srv_rr)
 259                 goto oom;
 260
 261         s->srv_rr->ttl = MDNS_DEFAULT_TTL;
 262         s->srv_rr->srv.priority = s->priority;
 263         s->srv_rr->srv.weight = s->weight;
 264         s->srv_rr->srv.port = s->port;
 265         s->srv_rr->srv.name = strdup(s->manager->mdns_hostname);
 266         if (!s->srv_rr->srv.name)
 267                 goto oom;
 268
 269         return 0;
 270
 271 oom:
 272         LIST_FOREACH(items, txt_data, s->txt_data_items)
 273                 txt_data->rr = dns_resource_record_unref(txt_data->rr);
 274         s->ptr_rr = dns_resource_record_unref(s->ptr_rr);
 275         s->srv_rr = dns_resource_record_unref(s->srv_rr);
 276         return -ENOMEM;
 277 }
 278
 279 int dnssd_txt_item_new_from_string(const char *key, const char *value, DnsTxtItem **ret_item) {
 280         size_t length;
 281         DnsTxtItem *i;
 282
 283         length = strlen(key);
 284
 285         if (!isempty(value))
 286                 length += strlen(value) + 1; /* length of value plus '=' */
 287
 288         i = malloc0(offsetof(DnsTxtItem, data) + length + 1); /* for safety reasons we add an extra NUL byte */
 289         if (!i)
 290                 return -ENOMEM;
 291
 292         memcpy(i->data, key, strlen(key));
 293         if (!isempty(value)) {
 294                 memcpy(i->data + strlen(key), "=", 1);
 295                 memcpy(i->data + strlen(key) + 1, value, strlen(value));
 296         }
 297         i->length = length;
 298
 299         *ret_item = TAKE_PTR(i);
 300
 301         return 0;
 302 }
 303
 304 int dnssd_txt_item_new_from_data(const char *key, const void *data, const size_t size, DnsTxtItem **ret_item) {
 305         size_t length;
 306         DnsTxtItem *i;
 307
 308         length = strlen(key);
 309
 310         if (size > 0)
 311                 length += size + 1; /* size of date plus '=' */
 312
 313         i = malloc0(offsetof(DnsTxtItem, data) + length + 1); /* for safety reasons we add an extra NUL byte */
 314         if (!i)
 315                 return -ENOMEM;
 316
 317         memcpy(i->data, key, strlen(key));
 318         if (size > 0) {
 319                 memcpy(i->data + strlen(key), "=", 1);
 320                 memcpy(i->data + strlen(key) + 1, data, size);
 321         }
 322         i->length = length;
 323
 324         *ret_item = TAKE_PTR(i);
 325
 326         return 0;
 327 }
 328
 329 int dnssd_signal_conflict(Manager *manager, const char *name) {
 330         DnssdService *s;
 331         int r;
 332
 333         if (sd_bus_is_ready(manager->bus) <= 0)
 334                 return 0;
 335
 336         HASHMAP_FOREACH(s, manager->dnssd_services) {
 337                 if (s->withdrawn)
 338                         continue;
 339
 340                 if (dns_name_equal(dns_resource_key_name(s->srv_rr->key), name)) {
 341                         _cleanup_free_ char *path = NULL;
 342
 343                         s->withdrawn = true;
 344
 345                         r = sd_bus_path_encode("/org/freedesktop/resolve1/dnssd", s->name, &path);
 346                         if (r < 0)
 347                                 return log_error_errno(r, "Can't get D-BUS object path: %m");
 348
 349                         r = sd_bus_emit_signal(manager->bus,
 350                                                path,
 351                                                "org.freedesktop.resolve1.DnssdService",
 352                                                "Conflicted",
 353                                                NULL);
 354                         if (r < 0)
 355                                 return log_error_errno(r, "Cannot emit signal: %m");
 356
 357                         break;
 358                 }
 359         }
 360
 361         return 0;
 362 }