src/resolve/resolved-dnssd.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2017 Dmitry Rozhkov
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include "conf-files.h"
  21 #include "conf-parser.h"
  22 #include "resolved-dnssd.h"
  23 #include "resolved-dns-rr.h"
  24 #include "resolved-manager.h"
  25 #include "specifier.h"
  26 #include "strv.h"
  27
  28 const char* const dnssd_service_dirs[] = {
  29         "/etc/systemd/dnssd",
  30         "/run/systemd/dnssd",
  31         "/usr/lib/systemd/dnssd",
  32 #ifdef HAVE_SPLIT_USR
  33         "/lib/systemd/dnssd",
  34 #endif
  35     NULL
  36 };
  37
  38 DnssdTxtData *dnssd_txtdata_free(DnssdTxtData *txt_data) {
  39         if (!txt_data)
  40                 return NULL;
  41
  42         dns_resource_record_unref(txt_data->rr);
  43         dns_txt_item_free_all(txt_data->txt);
  44
  45         return mfree(txt_data);
  46 }
  47
  48 DnssdTxtData *dnssd_txtdata_free_all(DnssdTxtData *txt_data) {
  49         DnssdTxtData *next;
  50
  51         if (!txt_data)
  52                 return NULL;
  53
  54         next = txt_data->items_next;
  55
  56         dnssd_txtdata_free(txt_data);
  57
  58         return dnssd_txtdata_free_all(next);
  59 }
  60
  61 DnssdService *dnssd_service_free(DnssdService *service) {
  62         if (!service)
  63                 return NULL;
  64
  65         if (service->manager)
  66                 hashmap_remove(service->manager->dnssd_services, service->name);
  67
  68         dns_resource_record_unref(service->ptr_rr);
  69         dns_resource_record_unref(service->srv_rr);
  70
  71         dnssd_txtdata_free_all(service->txt_data_items);
  72
  73         free(service->filename);
  74         free(service->name);
  75         free(service->type);
  76         free(service->name_template);
  77
  78         return mfree(service);
  79 }
  80
  81 static int dnssd_service_load(Manager *manager, const char *filename) {
  82         _cleanup_(dnssd_service_freep) DnssdService *service = NULL;
  83         _cleanup_(dnssd_txtdata_freep) DnssdTxtData *txt_data = NULL;
  84         char *d;
  85         const char *dropin_dirname;
  86         int r;
  87
  88         assert(manager);
  89         assert(filename);
  90
  91         service = new0(DnssdService, 1);
  92         if (!service)
  93                 return log_oom();
  94
  95         service->filename = strdup(filename);
  96         if (!service->filename)
  97                 return log_oom();
  98
  99         service->name = strdup(basename(filename));
 100         if (!service->name)
 101                 return log_oom();
 102
 103         d = endswith(service->name, ".dnssd");
 104         if (!d)
 105                 return -EINVAL;
 106
 107         assert(streq(d, ".dnssd"));
 108
 109         *d = '\0';
 110
 111         dropin_dirname = strjoina(service->name, ".dnssd.d");
 112
 113         r = config_parse_many(filename, dnssd_service_dirs, dropin_dirname,
 114                               "Service\0",
 115                               config_item_perf_lookup, resolved_dnssd_gperf_lookup,
 116                               false, service);
 117         if (r < 0)
 118                 return r;
 119
 120         if (!service->name_template) {
 121                 log_error("%s doesn't define service instance name", service->name);
 122                 return -EINVAL;
 123         }
 124
 125         if (!service->type) {
 126                 log_error("%s doesn't define service type", service->name);
 127                 return -EINVAL;
 128         }
 129
 130         if (LIST_IS_EMPTY(service->txt_data_items)) {
 131                 txt_data = new0(DnssdTxtData, 1);
 132                 if (!txt_data)
 133                         return log_oom();
 134
 135                 r = dns_txt_item_new_empty(&txt_data->txt);
 136                 if (r < 0)
 137                         return r;
 138
 139                 LIST_PREPEND(items, service->txt_data_items, txt_data);
 140                 txt_data = NULL;
 141         }
 142
 143         r = hashmap_ensure_allocated(&manager->dnssd_services, &string_hash_ops);
 144         if (r < 0)
 145                 return r;
 146
 147         r = hashmap_put(manager->dnssd_services, service->name, service);
 148         if (r < 0)
 149                 return r;
 150
 151         service->manager = manager;
 152
 153         r = dnssd_update_rrs(service);
 154         if (r < 0)
 155                 return r;
 156
 157         service = NULL;
 158
 159         return 0;
 160 }
 161
 162 static int specifier_dnssd_host_name(char specifier, void *data, void *userdata, char **ret) {
 163         DnssdService *s  = (DnssdService *) userdata;
 164         char *n;
 165
 166         assert(s);
 167         assert(s->manager);
 168         assert(s->manager->llmnr_hostname);
 169
 170         n = strdup(s->manager->llmnr_hostname);
 171         if (!n)
 172                 return -ENOMEM;
 173
 174         *ret = n;
 175         return 0;
 176 }
 177
 178 int dnssd_render_instance_name(DnssdService *s, char **ret_name) {
 179         static const Specifier specifier_table[] = {
 180                 { 'b', specifier_boot_id,         NULL },
 181                 { 'H', specifier_dnssd_host_name, NULL },
 182                 { 'm', specifier_machine_id, NULL },
 183                 { 'v', specifier_kernel_release,  NULL },
 184                 {}
 185         };
 186         _cleanup_free_ char *name = NULL;
 187         int r;
 188
 189         assert(s);
 190         assert(s->name_template);
 191
 192         r = specifier_printf(s->name_template, specifier_table, s, &name);
 193         if (r < 0)
 194                 return log_debug_errno(r, "Failed to replace specifiers: %m");
 195
 196         if (!dns_service_name_is_valid(name)) {
 197                 log_debug("Service instance name '%s' is invalid.", name);
 198                 return -EINVAL;
 199         }
 200
 201         *ret_name = TAKE_PTR(name);
 202
 203         return 0;
 204 }
 205
 206 int dnssd_load(Manager *manager) {
 207         _cleanup_strv_free_ char **files = NULL;
 208         char **f;
 209         int r;
 210
 211         assert(manager);
 212
 213         if (manager->mdns_support != RESOLVE_SUPPORT_YES)
 214                 return 0;
 215
 216         r = conf_files_list_strv(&files, ".dnssd", NULL, 0, dnssd_service_dirs);
 217         if (r < 0)
 218                 return log_error_errno(r, "Failed to enumerate .dnssd files: %m");
 219
 220         STRV_FOREACH_BACKWARDS(f, files) {
 221                 r = dnssd_service_load(manager, *f);
 222                 if (r < 0)
 223                         log_warning_errno(r, "Failed to load '%s': %m", *f);;
 224         }
 225
 226         return 0;
 227 }
 228
 229 int dnssd_update_rrs(DnssdService *s) {
 230         _cleanup_free_ char *n = NULL;
 231         _cleanup_free_ char *service_name = NULL;
 232         _cleanup_free_ char *full_name = NULL;
 233         DnssdTxtData *txt_data;
 234         int r;
 235
 236         assert(s);
 237         assert(s->txt_data_items);
 238         assert(s->manager);
 239
 240         s->ptr_rr = dns_resource_record_unref(s->ptr_rr);
 241         s->srv_rr = dns_resource_record_unref(s->srv_rr);
 242         LIST_FOREACH(items, txt_data, s->txt_data_items)
 243                 txt_data->rr = dns_resource_record_unref(txt_data->rr);
 244
 245         r = dnssd_render_instance_name(s, &n);
 246         if (r < 0)
 247                 return r;
 248
 249         r = dns_name_concat(s->type, "local", &service_name);
 250         if (r < 0)
 251                 return r;
 252         r = dns_name_concat(n, service_name, &full_name);
 253         if (r < 0)
 254                 return r;
 255
 256         LIST_FOREACH(items, txt_data, s->txt_data_items) {
 257                 txt_data->rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_TXT,
 258                                                             full_name);
 259                 if (!txt_data->rr)
 260                         goto oom;
 261
 262                 txt_data->rr->ttl = MDNS_DEFAULT_TTL;
 263                 txt_data->rr->txt.items = dns_txt_item_copy(txt_data->txt);
 264                 if (!txt_data->rr->txt.items)
 265                         goto oom;
 266         }
 267
 268         s->ptr_rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR,
 269                                                  service_name);
 270         if (!s->ptr_rr)
 271                 goto oom;
 272
 273         s->ptr_rr->ttl = MDNS_DEFAULT_TTL;
 274         s->ptr_rr->ptr.name = strdup(full_name);
 275         if (!s->ptr_rr->ptr.name)
 276                 goto oom;
 277
 278         s->srv_rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_SRV,
 279                                                  full_name);
 280         if (!s->srv_rr)
 281                 goto oom;
 282
 283         s->srv_rr->ttl = MDNS_DEFAULT_TTL;
 284         s->srv_rr->srv.priority = s->priority;
 285         s->srv_rr->srv.weight = s->weight;
 286         s->srv_rr->srv.port = s->port;
 287         s->srv_rr->srv.name = strdup(s->manager->mdns_hostname);
 288         if (!s->srv_rr->srv.name)
 289                 goto oom;
 290
 291         return 0;
 292
 293 oom:
 294         LIST_FOREACH(items, txt_data, s->txt_data_items)
 295                 txt_data->rr = dns_resource_record_unref(txt_data->rr);
 296         s->ptr_rr = dns_resource_record_unref(s->ptr_rr);
 297         s->srv_rr = dns_resource_record_unref(s->srv_rr);
 298         return -ENOMEM;
 299 }
 300
 301 int dnssd_txt_item_new_from_string(const char *key, const char *value, DnsTxtItem **ret_item) {
 302         size_t length;
 303         DnsTxtItem *i;
 304
 305         length = strlen(key);
 306
 307         if (!isempty(value))
 308                 length += strlen(value) + 1; /* length of value plus '=' */
 309
 310         i = malloc0(offsetof(DnsTxtItem, data) + length + 1); /* for safety reasons we add an extra NUL byte */
 311         if (!i)
 312                 return -ENOMEM;
 313
 314         memcpy(i->data, key, strlen(key));
 315         if (!isempty(value)) {
 316                 memcpy(i->data + strlen(key), "=", 1);
 317                 memcpy(i->data + strlen(key) + 1, value, strlen(value));
 318         }
 319         i->length = length;
 320
 321         *ret_item = TAKE_PTR(i);
 322
 323         return 0;
 324 }
 325
 326 int dnssd_txt_item_new_from_data(const char *key, const void *data, const size_t size, DnsTxtItem **ret_item) {
 327         size_t length;
 328         DnsTxtItem *i;
 329
 330         length = strlen(key);
 331
 332         if (size > 0)
 333                 length += size + 1; /* size of date plus '=' */
 334
 335         i = malloc0(offsetof(DnsTxtItem, data) + length + 1); /* for safety reasons we add an extra NUL byte */
 336         if (!i)
 337                 return -ENOMEM;
 338
 339         memcpy(i->data, key, strlen(key));
 340         if (size > 0) {
 341                 memcpy(i->data + strlen(key), "=", 1);
 342                 memcpy(i->data + strlen(key) + 1, data, size);
 343         }
 344         i->length = length;
 345
 346         *ret_item = TAKE_PTR(i);
 347
 348         return 0;
 349 }
 350
 351 void dnssd_signal_conflict(Manager *manager, const char *name) {
 352         Iterator i;
 353         DnssdService *s;
 354         int r;
 355
 356         HASHMAP_FOREACH(s, manager->dnssd_services, i) {
 357                 if (s->withdrawn)
 358                         continue;
 359
 360                 if (dns_name_equal(dns_resource_key_name(s->srv_rr->key), name)) {
 361                         _cleanup_free_ char *path = NULL;
 362
 363                         s->withdrawn = true;
 364
 365                         r = sd_bus_path_encode("/org/freedesktop/resolve1/dnssd", s->name, &path);
 366                         if (r < 0) {
 367                                 log_error_errno(r, "Can't get D-BUS object path: %m");
 368                                 return;
 369                         }
 370
 371                         r = sd_bus_emit_signal(manager->bus,
 372                                                path,
 373                                                "org.freedesktop.resolve1.DnssdService",
 374                                                "Conflicted",
 375                                                NULL);
 376                         if (r < 0) {
 377                                 log_error_errno(r, "Cannot emit signal: %m");
 378                                 return;
 379                         }
 380
 381                         break;
 382                 }
 383         }
 384 }