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 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         dns_resource_record_unref(service->txt_rr);
  48
  49         free(service->filename);
  50         free(service->name);
  51         free(service->type);
  52         free(service->name_template);
  53         dns_txt_item_free_all(service->txt);
  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         char *d;
  61         const char *dropin_dirname;
  62         int r;
  63
  64         assert(manager);
  65         assert(filename);
  66
  67         service = new0(DnssdService, 1);
  68         if (!service)
  69                 return log_oom();
  70
  71         service->filename = strdup(filename);
  72         if (!service->filename)
  73                 return log_oom();
  74
  75         service->name = strdup(basename(filename));
  76         if (!service->name)
  77                 return log_oom();
  78
  79         d = endswith(service->name, ".dnssd");
  80         if (!d)
  81                 return -EINVAL;
  82
  83         assert(streq(d, ".dnssd"));
  84
  85         *d = '\0';
  86
  87         dropin_dirname = strjoina(service->name, ".dnssd.d");
  88
  89         r = config_parse_many(filename, dnssd_service_dirs, dropin_dirname,
  90                               "Service\0",
  91                               config_item_perf_lookup, resolved_dnssd_gperf_lookup,
  92                               false, service);
  93         if (r < 0)
  94                 return r;
  95
  96         if (!service->name_template) {
  97                 log_error("%s doesn't define service instance name", service->name);
  98                 return -EINVAL;
  99         }
 100
 101         if (!service->type) {
 102                 log_error("%s doesn't define service type", service->name);
 103                 return -EINVAL;
 104         }
 105
 106         if (!service->txt) {
 107                 r = dns_txt_item_new_empty(&service->txt);
 108                 if (r < 0)
 109                         return r;
 110         }
 111
 112         r = hashmap_ensure_allocated(&manager->dnssd_services, &string_hash_ops);
 113         if (r < 0)
 114                 return r;
 115
 116         r = hashmap_put(manager->dnssd_services, service->name, service);
 117         if (r < 0)
 118                 return r;
 119
 120         service->manager = manager;
 121
 122         r = dnssd_update_rrs(service);
 123         if (r < 0)
 124                 return r;
 125
 126         service = NULL;
 127
 128         return 0;
 129 }
 130
 131 static int specifier_dnssd_host_name(char specifier, void *data, void *userdata, char **ret) {
 132         DnssdService *s  = (DnssdService *) userdata;
 133         char *n;
 134
 135         assert(s);
 136         assert(s->manager);
 137         assert(s->manager->llmnr_hostname);
 138
 139         n = strdup(s->manager->llmnr_hostname);
 140         if (!n)
 141                 return -ENOMEM;
 142
 143         *ret = n;
 144         return 0;
 145 }
 146
 147 int dnssd_render_instance_name(DnssdService *s, char **ret_name) {
 148         static const Specifier specifier_table[] = {
 149                 { 'b', specifier_boot_id,         NULL },
 150                 { 'H', specifier_dnssd_host_name, NULL },
 151                 { 'm', specifier_machine_id, NULL },
 152                 { 'v', specifier_kernel_release,  NULL },
 153                 {}
 154         };
 155         _cleanup_free_ char *name = NULL;
 156         int r;
 157
 158         assert(s);
 159         assert(s->name_template);
 160
 161         r = specifier_printf(s->name_template, specifier_table, s, &name);
 162         if (r < 0)
 163                 return log_debug_errno(r, "Failed to replace specifiers: %m");
 164
 165         if (!dns_service_name_is_valid(name)) {
 166                 log_debug("Service instance name '%s' is invalid.", name);
 167                 return -EINVAL;
 168         }
 169
 170         *ret_name = name;
 171         name = NULL;
 172
 173         return 0;
 174 }
 175
 176 int dnssd_load(Manager *manager) {
 177         _cleanup_strv_free_ char **files = NULL;
 178         char **f;
 179         int r;
 180
 181         assert(manager);
 182
 183         if (manager->mdns_support != RESOLVE_SUPPORT_YES)
 184                 return 0;
 185
 186         r = conf_files_list_strv(&files, ".dnssd", NULL, 0, dnssd_service_dirs);
 187         if (r < 0)
 188                 return log_error_errno(r, "Failed to enumerate .dnssd files: %m");
 189
 190         STRV_FOREACH_BACKWARDS(f, files) {
 191                 r = dnssd_service_load(manager, *f);
 192                 if (r < 0)
 193                         log_warning_errno(r, "Failed to load '%s': %m", *f);;
 194         }
 195
 196         return 0;
 197 }
 198
 199 int dnssd_update_rrs(DnssdService *s) {
 200         _cleanup_free_ char *n = NULL;
 201         _cleanup_free_ char *service_name = NULL;
 202         _cleanup_free_ char *full_name = NULL;
 203         int r;
 204
 205         assert(s);
 206         assert(s->txt);
 207         assert(s->manager);
 208
 209         s->ptr_rr = dns_resource_record_unref(s->ptr_rr);
 210         s->srv_rr = dns_resource_record_unref(s->srv_rr);
 211         s->txt_rr = dns_resource_record_unref(s->txt_rr);
 212
 213         r = dnssd_render_instance_name(s, &n);
 214         if (r < 0)
 215                 return r;
 216
 217         r = dns_name_concat(s->type, "local", &service_name);
 218         if (r < 0)
 219                 return r;
 220         r = dns_name_concat(n, service_name, &full_name);
 221         if (r < 0)
 222                 return r;
 223
 224         s->txt_rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_TXT,
 225                                                  full_name);
 226         if (!s->txt_rr)
 227                 goto oom;
 228
 229         s->txt_rr->ttl = MDNS_DEFAULT_TTL;
 230         s->txt_rr->txt.items = dns_txt_item_copy(s->txt);
 231         if (!s->txt_rr->txt.items)
 232                 goto oom;
 233
 234         s->ptr_rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR,
 235                                                  service_name);
 236         if (!s->ptr_rr)
 237                 goto oom;
 238
 239         s->ptr_rr->ttl = MDNS_DEFAULT_TTL;
 240         s->ptr_rr->ptr.name = strdup(full_name);
 241         if (!s->ptr_rr->ptr.name)
 242                 goto oom;
 243
 244         s->srv_rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_SRV,
 245                                                  full_name);
 246         if (!s->srv_rr)
 247                 goto oom;
 248
 249         s->srv_rr->ttl = MDNS_DEFAULT_TTL;
 250         s->srv_rr->srv.priority = s->priority;
 251         s->srv_rr->srv.weight = s->weight;
 252         s->srv_rr->srv.port = s->port;
 253         s->srv_rr->srv.name = strdup(s->manager->mdns_hostname);
 254         if (!s->srv_rr->srv.name)
 255                 goto oom;
 256
 257         return 0;
 258
 259 oom:
 260         s->txt_rr = dns_resource_record_unref(s->txt_rr);
 261         s->ptr_rr = dns_resource_record_unref(s->ptr_rr);
 262         s->srv_rr = dns_resource_record_unref(s->srv_rr);
 263         return -ENOMEM;
 264 }
 265
 266 int dnssd_txt_item_new_from_string(const char *key, const char *value, DnsTxtItem **ret_item) {
 267         size_t length;
 268         DnsTxtItem *i;
 269
 270         length = strlen(key);
 271
 272         if (!isempty(value))
 273                 length += strlen(value) + 1; /* length of value plus '=' */
 274
 275         i = malloc0(offsetof(DnsTxtItem, data) + length + 1); /* for safety reasons we add an extra NUL byte */
 276         if (!i)
 277                 return -ENOMEM;
 278
 279         memcpy(i->data, key, strlen(key));
 280         if (!isempty(value)) {
 281                 memcpy(i->data + strlen(key), "=", 1);
 282                 memcpy(i->data + strlen(key) + 1, value, strlen(value));
 283         }
 284         i->length = length;
 285
 286         *ret_item = i;
 287         i = NULL;
 288
 289         return 0;
 290 }
 291
 292 int dnssd_txt_item_new_from_data(const char *key, const void *data, const size_t size, DnsTxtItem **ret_item) {
 293         size_t length;
 294         DnsTxtItem *i;
 295
 296         length = strlen(key);
 297
 298         if (size > 0)
 299                 length += size + 1; /* size of date plus '=' */
 300
 301         i = malloc0(offsetof(DnsTxtItem, data) + length + 1); /* for safety reasons we add an extra NUL byte */
 302         if (!i)
 303                 return -ENOMEM;
 304
 305         memcpy(i->data, key, strlen(key));
 306         if (size > 0) {
 307                 memcpy(i->data + strlen(key), "=", 1);
 308                 memcpy(i->data + strlen(key) + 1, data, size);
 309         }
 310         i->length = length;
 311
 312         *ret_item = i;
 313         i = NULL;
 314
 315         return 0;
 316 }
 317
 318 void dnssd_signal_conflict(Manager *manager, const char *name) {
 319         Iterator i;
 320         DnssdService *s;
 321         int r;
 322
 323         HASHMAP_FOREACH(s, manager->dnssd_services, i) {
 324                 if (s->withdrawn)
 325                         continue;
 326
 327                 if (dns_name_equal(dns_resource_key_name(s->srv_rr->key), name)) {
 328                         _cleanup_free_ char *path = NULL;
 329
 330                         s->withdrawn = true;
 331
 332                         r = sd_bus_path_encode("/org/freedesktop/resolve1/dnssd", s->name, &path);
 333                         if (r < 0) {
 334                                 log_error_errno(r, "Can't get D-BUS object path: %m");
 335                                 return;
 336                         }
 337
 338                         r = sd_bus_emit_signal(manager->bus,
 339                                                path,
 340                                                "org.freedesktop.resolve1.DnssdService",
 341                                                "Conflicted",
 342                                                NULL);
 343                         if (r < 0) {
 344                                 log_error_errno(r, "Cannot emit signal: %m");
 345                                 return;
 346                         }
 347
 348                         break;
 349                 }
 350         }
 351 }