src/resolve/resolved-dns-question.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include "alloc-util.h"
   4 #include "dns-domain.h"
   5 #include "dns-type.h"
   6 #include "resolved-dns-question.h"
   7
   8 DnsQuestion *dns_question_new(size_t n) {
   9         DnsQuestion *q;
  10
  11         assert(n > 0);
  12
  13         q = malloc0(offsetof(DnsQuestion, keys) + sizeof(DnsResourceKey*) * n);
  14         if (!q)
  15                 return NULL;
  16
  17         q->n_ref = 1;
  18         q->n_allocated = n;
  19
  20         return q;
  21 }
  22
  23 static DnsQuestion *dns_question_free(DnsQuestion *q) {
  24         size_t i;
  25
  26         assert(q);
  27
  28         for (i = 0; i < q->n_keys; i++)
  29                 dns_resource_key_unref(q->keys[i]);
  30         return mfree(q);
  31 }
  32
  33 DEFINE_TRIVIAL_REF_UNREF_FUNC(DnsQuestion, dns_question, dns_question_free);
  34
  35 int dns_question_add(DnsQuestion *q, DnsResourceKey *key) {
  36         size_t i;
  37         int r;
  38
  39         assert(key);
  40
  41         if (!q)
  42                 return -ENOSPC;
  43
  44         for (i = 0; i < q->n_keys; i++) {
  45                 r = dns_resource_key_equal(q->keys[i], key);
  46                 if (r < 0)
  47                         return r;
  48                 if (r > 0)
  49                         return 0;
  50         }
  51
  52         if (q->n_keys >= q->n_allocated)
  53                 return -ENOSPC;
  54
  55         q->keys[q->n_keys++] = dns_resource_key_ref(key);
  56         return 0;
  57 }
  58
  59 int dns_question_matches_rr(DnsQuestion *q, DnsResourceRecord *rr, const char *search_domain) {
  60         size_t i;
  61         int r;
  62
  63         assert(rr);
  64
  65         if (!q)
  66                 return 0;
  67
  68         for (i = 0; i < q->n_keys; i++) {
  69                 r = dns_resource_key_match_rr(q->keys[i], rr, search_domain);
  70                 if (r != 0)
  71                         return r;
  72         }
  73
  74         return 0;
  75 }
  76
  77 int dns_question_matches_cname_or_dname(DnsQuestion *q, DnsResourceRecord *rr, const char *search_domain) {
  78         size_t i;
  79         int r;
  80
  81         assert(rr);
  82
  83         if (!q)
  84                 return 0;
  85
  86         if (!IN_SET(rr->key->type, DNS_TYPE_CNAME, DNS_TYPE_DNAME))
  87                 return 0;
  88
  89         for (i = 0; i < q->n_keys; i++) {
  90                 /* For a {C,D}NAME record we can never find a matching {C,D}NAME record */
  91                 if (!dns_type_may_redirect(q->keys[i]->type))
  92                         return 0;
  93
  94                 r = dns_resource_key_match_cname_or_dname(q->keys[i], rr->key, search_domain);
  95                 if (r != 0)
  96                         return r;
  97         }
  98
  99         return 0;
 100 }
 101
 102 int dns_question_is_valid_for_query(DnsQuestion *q) {
 103         const char *name;
 104         size_t i;
 105         int r;
 106
 107         if (!q)
 108                 return 0;
 109
 110         if (q->n_keys <= 0)
 111                 return 0;
 112
 113         if (q->n_keys > 65535)
 114                 return 0;
 115
 116         name = dns_resource_key_name(q->keys[0]);
 117         if (!name)
 118                 return 0;
 119
 120         /* Check that all keys in this question bear the same name */
 121         for (i = 0; i < q->n_keys; i++) {
 122                 assert(q->keys[i]);
 123
 124                 if (i > 0) {
 125                         r = dns_name_equal(dns_resource_key_name(q->keys[i]), name);
 126                         if (r <= 0)
 127                                 return r;
 128                 }
 129
 130                 if (!dns_type_is_valid_query(q->keys[i]->type))
 131                         return 0;
 132         }
 133
 134         return 1;
 135 }
 136
 137 int dns_question_contains(DnsQuestion *a, const DnsResourceKey *k) {
 138         size_t j;
 139         int r;
 140
 141         assert(k);
 142
 143         if (!a)
 144                 return 0;
 145
 146         for (j = 0; j < a->n_keys; j++) {
 147                 r = dns_resource_key_equal(a->keys[j], k);
 148                 if (r != 0)
 149                         return r;
 150         }
 151
 152         return 0;
 153 }
 154
 155 int dns_question_is_equal(DnsQuestion *a, DnsQuestion *b) {
 156         size_t j;
 157         int r;
 158
 159         if (a == b)
 160                 return 1;
 161
 162         if (!a)
 163                 return !b || b->n_keys == 0;
 164         if (!b)
 165                 return a->n_keys == 0;
 166
 167         /* Checks if all keys in a are also contained b, and vice versa */
 168
 169         for (j = 0; j < a->n_keys; j++) {
 170                 r = dns_question_contains(b, a->keys[j]);
 171                 if (r <= 0)
 172                         return r;
 173         }
 174
 175         for (j = 0; j < b->n_keys; j++) {
 176                 r = dns_question_contains(a, b->keys[j]);
 177                 if (r <= 0)
 178                         return r;
 179         }
 180
 181         return 1;
 182 }
 183
 184 int dns_question_cname_redirect(DnsQuestion *q, const DnsResourceRecord *cname, DnsQuestion **ret) {
 185         _cleanup_(dns_question_unrefp) DnsQuestion *n = NULL;
 186         DnsResourceKey *key;
 187         bool same = true;
 188         int r;
 189
 190         assert(cname);
 191         assert(ret);
 192         assert(IN_SET(cname->key->type, DNS_TYPE_CNAME, DNS_TYPE_DNAME));
 193
 194         if (dns_question_size(q) <= 0) {
 195                 *ret = NULL;
 196                 return 0;
 197         }
 198
 199         DNS_QUESTION_FOREACH(key, q) {
 200                 _cleanup_free_ char *destination = NULL;
 201                 const char *d;
 202
 203                 if (cname->key->type == DNS_TYPE_CNAME)
 204                         d = cname->cname.name;
 205                 else {
 206                         r = dns_name_change_suffix(dns_resource_key_name(key), dns_resource_key_name(cname->key), cname->dname.name, &destination);
 207                         if (r < 0)
 208                                 return r;
 209                         if (r == 0)
 210                                 continue;
 211
 212                         d = destination;
 213                 }
 214
 215                 r = dns_name_equal(dns_resource_key_name(key), d);
 216                 if (r < 0)
 217                         return r;
 218
 219                 if (r == 0) {
 220                         same = false;
 221                         break;
 222                 }
 223         }
 224
 225         /* Fully the same, indicate we didn't do a thing */
 226         if (same) {
 227                 *ret = NULL;
 228                 return 0;
 229         }
 230
 231         n = dns_question_new(q->n_keys);
 232         if (!n)
 233                 return -ENOMEM;
 234
 235         /* Create a new question, and patch in the new name */
 236         DNS_QUESTION_FOREACH(key, q) {
 237                 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *k = NULL;
 238
 239                 k = dns_resource_key_new_redirect(key, cname);
 240                 if (!k)
 241                         return -ENOMEM;
 242
 243                 r = dns_question_add(n, k);
 244                 if (r < 0)
 245                         return r;
 246         }
 247
 248         *ret = TAKE_PTR(n);
 249
 250         return 1;
 251 }
 252
 253 const char *dns_question_first_name(DnsQuestion *q) {
 254
 255         if (!q)
 256                 return NULL;
 257
 258         if (q->n_keys < 1)
 259                 return NULL;
 260
 261         return dns_resource_key_name(q->keys[0]);
 262 }
 263
 264 int dns_question_new_address(DnsQuestion **ret, int family, const char *name, bool convert_idna) {
 265         _cleanup_(dns_question_unrefp) DnsQuestion *q = NULL;
 266         _cleanup_free_ char *buf = NULL;
 267         int r;
 268
 269         assert(ret);
 270         assert(name);
 271
 272         if (!IN_SET(family, AF_INET, AF_INET6, AF_UNSPEC))
 273                 return -EAFNOSUPPORT;
 274
 275         if (convert_idna) {
 276                 r = dns_name_apply_idna(name, &buf);
 277                 if (r < 0)
 278                         return r;
 279                 if (r > 0 && !streq(name, buf))
 280                         name = buf;
 281                 else
 282                         /* We did not manage to create convert the idna name, or it's
 283                          * the same as the original name. We assume the caller already
 284                          * created an uncoverted question, so let's not repeat work
 285                          * unnecessarily. */
 286                         return -EALREADY;
 287         }
 288
 289         q = dns_question_new(family == AF_UNSPEC ? 2 : 1);
 290         if (!q)
 291                 return -ENOMEM;
 292
 293         if (family != AF_INET6) {
 294                 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
 295
 296                 key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_A, name);
 297                 if (!key)
 298                         return -ENOMEM;
 299
 300                 r = dns_question_add(q, key);
 301                 if (r < 0)
 302                         return r;
 303         }
 304
 305         if (family != AF_INET) {
 306                 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
 307
 308                 key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_AAAA, name);
 309                 if (!key)
 310                         return -ENOMEM;
 311
 312                 r = dns_question_add(q, key);
 313                 if (r < 0)
 314                         return r;
 315         }
 316
 317         *ret = TAKE_PTR(q);
 318
 319         return 0;
 320 }
 321
 322 int dns_question_new_reverse(DnsQuestion **ret, int family, const union in_addr_union *a) {
 323         _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
 324         _cleanup_(dns_question_unrefp) DnsQuestion *q = NULL;
 325         _cleanup_free_ char *reverse = NULL;
 326         int r;
 327
 328         assert(ret);
 329         assert(a);
 330
 331         if (!IN_SET(family, AF_INET, AF_INET6, AF_UNSPEC))
 332                 return -EAFNOSUPPORT;
 333
 334         r = dns_name_reverse(family, a, &reverse);
 335         if (r < 0)
 336                 return r;
 337
 338         q = dns_question_new(1);
 339         if (!q)
 340                 return -ENOMEM;
 341
 342         key = dns_resource_key_new_consume(DNS_CLASS_IN, DNS_TYPE_PTR, reverse);
 343         if (!key)
 344                 return -ENOMEM;
 345
 346         reverse = NULL;
 347
 348         r = dns_question_add(q, key);
 349         if (r < 0)
 350                 return r;
 351
 352         *ret = TAKE_PTR(q);
 353
 354         return 0;
 355 }
 356
 357 int dns_question_new_service(
 358                 DnsQuestion **ret,
 359                 const char *service,
 360                 const char *type,
 361                 const char *domain,
 362                 bool with_txt,
 363                 bool convert_idna) {
 364
 365         _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
 366         _cleanup_(dns_question_unrefp) DnsQuestion *q = NULL;
 367         _cleanup_free_ char *buf = NULL, *joined = NULL;
 368         const char *name;
 369         int r;
 370
 371         assert(ret);
 372
 373         /* We support three modes of invocation:
 374          *
 375          * 1. Only a domain is specified, in which case we assume a properly encoded SRV RR name, including service
 376          *    type and possibly a service name. If specified in this way we assume it's already IDNA converted if
 377          *    that's necessary.
 378          *
 379          * 2. Both service type and a domain specified, in which case a normal SRV RR is assumed, without a DNS-SD
 380          *    style prefix. In this case we'll IDNA convert the domain, if that's requested.
 381          *
 382          * 3. All three of service name, type and domain are specified, in which case a DNS-SD service is put
 383          *    together. The service name is never IDNA converted, and the domain is if requested.
 384          *
 385          * It's not supported to specify a service name without a type, or no domain name.
 386          */
 387
 388         if (!domain)
 389                 return -EINVAL;
 390
 391         if (type) {
 392                 if (convert_idna) {
 393                         r = dns_name_apply_idna(domain, &buf);
 394                         if (r < 0)
 395                                 return r;
 396                         if (r > 0)
 397                                 domain = buf;
 398                 }
 399
 400                 r = dns_service_join(service, type, domain, &joined);
 401                 if (r < 0)
 402                         return r;
 403
 404                 name = joined;
 405         } else {
 406                 if (service)
 407                         return -EINVAL;
 408
 409                 name = domain;
 410         }
 411
 412         q = dns_question_new(1 + with_txt);
 413         if (!q)
 414                 return -ENOMEM;
 415
 416         key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_SRV, name);
 417         if (!key)
 418                 return -ENOMEM;
 419
 420         r = dns_question_add(q, key);
 421         if (r < 0)
 422                 return r;
 423
 424         if (with_txt) {
 425                 dns_resource_key_unref(key);
 426                 key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_TXT, name);
 427                 if (!key)
 428                         return -ENOMEM;
 429
 430                 r = dns_question_add(q, key);
 431                 if (r < 0)
 432                         return r;
 433         }
 434
 435         *ret = TAKE_PTR(q);
 436
 437         return 0;
 438 }