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_raw(DnsQuestion *q, DnsResourceKey *key) {
  36         /* Insert without checking for duplicates. */
  37
  38         assert(key);
  39         assert(q);
  40
  41         if (q->n_keys >= q->n_allocated)
  42                 return -ENOSPC;
  43
  44         q->keys[q->n_keys++] = dns_resource_key_ref(key);
  45         return 0;
  46 }
  47
  48 int dns_question_add(DnsQuestion *q, DnsResourceKey *key) {
  49         int r;
  50
  51         assert(key);
  52
  53         if (!q)
  54                 return -ENOSPC;
  55
  56         for (size_t i = 0; i < q->n_keys; i++) {
  57                 r = dns_resource_key_equal(q->keys[i], key);
  58                 if (r < 0)
  59                         return r;
  60                 if (r > 0)
  61                         return 0;
  62         }
  63
  64         return dns_question_add_raw(q, key);
  65 }
  66
  67 int dns_question_matches_rr(DnsQuestion *q, DnsResourceRecord *rr, const char *search_domain) {
  68         size_t i;
  69         int r;
  70
  71         assert(rr);
  72
  73         if (!q)
  74                 return 0;
  75
  76         for (i = 0; i < q->n_keys; i++) {
  77                 r = dns_resource_key_match_rr(q->keys[i], rr, search_domain);
  78                 if (r != 0)
  79                         return r;
  80         }
  81
  82         return 0;
  83 }
  84
  85 int dns_question_matches_cname_or_dname(DnsQuestion *q, DnsResourceRecord *rr, const char *search_domain) {
  86         size_t i;
  87         int r;
  88
  89         assert(rr);
  90
  91         if (!q)
  92                 return 0;
  93
  94         if (!IN_SET(rr->key->type, DNS_TYPE_CNAME, DNS_TYPE_DNAME))
  95                 return 0;
  96
  97         for (i = 0; i < q->n_keys; i++) {
  98                 /* For a {C,D}NAME record we can never find a matching {C,D}NAME record */
  99                 if (!dns_type_may_redirect(q->keys[i]->type))
 100                         return 0;
 101
 102                 r = dns_resource_key_match_cname_or_dname(q->keys[i], rr->key, search_domain);
 103                 if (r != 0)
 104                         return r;
 105         }
 106
 107         return 0;
 108 }
 109
 110 int dns_question_is_valid_for_query(DnsQuestion *q) {
 111         const char *name;
 112         size_t i;
 113         int r;
 114
 115         if (!q)
 116                 return 0;
 117
 118         if (q->n_keys <= 0)
 119                 return 0;
 120
 121         if (q->n_keys > 65535)
 122                 return 0;
 123
 124         name = dns_resource_key_name(q->keys[0]);
 125         if (!name)
 126                 return 0;
 127
 128         /* Check that all keys in this question bear the same name */
 129         for (i = 0; i < q->n_keys; i++) {
 130                 assert(q->keys[i]);
 131
 132                 if (i > 0) {
 133                         r = dns_name_equal(dns_resource_key_name(q->keys[i]), name);
 134                         if (r <= 0)
 135                                 return r;
 136                 }
 137
 138                 if (!dns_type_is_valid_query(q->keys[i]->type))
 139                         return 0;
 140         }
 141
 142         return 1;
 143 }
 144
 145 int dns_question_contains(DnsQuestion *a, const DnsResourceKey *k) {
 146         size_t j;
 147         int r;
 148
 149         assert(k);
 150
 151         if (!a)
 152                 return 0;
 153
 154         for (j = 0; j < a->n_keys; j++) {
 155                 r = dns_resource_key_equal(a->keys[j], k);
 156                 if (r != 0)
 157                         return r;
 158         }
 159
 160         return 0;
 161 }
 162
 163 int dns_question_is_equal(DnsQuestion *a, DnsQuestion *b) {
 164         size_t j;
 165         int r;
 166
 167         if (a == b)
 168                 return 1;
 169
 170         if (!a)
 171                 return !b || b->n_keys == 0;
 172         if (!b)
 173                 return a->n_keys == 0;
 174
 175         /* Checks if all keys in a are also contained b, and vice versa */
 176
 177         for (j = 0; j < a->n_keys; j++) {
 178                 r = dns_question_contains(b, a->keys[j]);
 179                 if (r <= 0)
 180                         return r;
 181         }
 182
 183         for (j = 0; j < b->n_keys; j++) {
 184                 r = dns_question_contains(a, b->keys[j]);
 185                 if (r <= 0)
 186                         return r;
 187         }
 188
 189         return 1;
 190 }
 191
 192 int dns_question_cname_redirect(DnsQuestion *q, const DnsResourceRecord *cname, DnsQuestion **ret) {
 193         _cleanup_(dns_question_unrefp) DnsQuestion *n = NULL;
 194         DnsResourceKey *key;
 195         bool same = true;
 196         int r;
 197
 198         assert(cname);
 199         assert(ret);
 200         assert(IN_SET(cname->key->type, DNS_TYPE_CNAME, DNS_TYPE_DNAME));
 201
 202         if (dns_question_size(q) <= 0) {
 203                 *ret = NULL;
 204                 return 0;
 205         }
 206
 207         DNS_QUESTION_FOREACH(key, q) {
 208                 _cleanup_free_ char *destination = NULL;
 209                 const char *d;
 210
 211                 if (cname->key->type == DNS_TYPE_CNAME)
 212                         d = cname->cname.name;
 213                 else {
 214                         r = dns_name_change_suffix(dns_resource_key_name(key), dns_resource_key_name(cname->key), cname->dname.name, &destination);
 215                         if (r < 0)
 216                                 return r;
 217                         if (r == 0)
 218                                 continue;
 219
 220                         d = destination;
 221                 }
 222
 223                 r = dns_name_equal(dns_resource_key_name(key), d);
 224                 if (r < 0)
 225                         return r;
 226
 227                 if (r == 0) {
 228                         same = false;
 229                         break;
 230                 }
 231         }
 232
 233         /* Fully the same, indicate we didn't do a thing */
 234         if (same) {
 235                 *ret = NULL;
 236                 return 0;
 237         }
 238
 239         n = dns_question_new(q->n_keys);
 240         if (!n)
 241                 return -ENOMEM;
 242
 243         /* Create a new question, and patch in the new name */
 244         DNS_QUESTION_FOREACH(key, q) {
 245                 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *k = NULL;
 246
 247                 k = dns_resource_key_new_redirect(key, cname);
 248                 if (!k)
 249                         return -ENOMEM;
 250
 251                 r = dns_question_add(n, k);
 252                 if (r < 0)
 253                         return r;
 254         }
 255
 256         *ret = TAKE_PTR(n);
 257
 258         return 1;
 259 }
 260
 261 const char *dns_question_first_name(DnsQuestion *q) {
 262
 263         if (!q)
 264                 return NULL;
 265
 266         if (q->n_keys < 1)
 267                 return NULL;
 268
 269         return dns_resource_key_name(q->keys[0]);
 270 }
 271
 272 int dns_question_new_address(DnsQuestion **ret, int family, const char *name, bool convert_idna) {
 273         _cleanup_(dns_question_unrefp) DnsQuestion *q = NULL;
 274         _cleanup_free_ char *buf = NULL;
 275         int r;
 276
 277         assert(ret);
 278         assert(name);
 279
 280         if (!IN_SET(family, AF_INET, AF_INET6, AF_UNSPEC))
 281                 return -EAFNOSUPPORT;
 282
 283         if (convert_idna) {
 284                 r = dns_name_apply_idna(name, &buf);
 285                 if (r < 0)
 286                         return r;
 287                 if (r > 0 && !streq(name, buf))
 288                         name = buf;
 289                 else
 290                         /* We did not manage to create convert the idna name, or it's
 291                          * the same as the original name. We assume the caller already
 292                          * created an unconverted question, so let's not repeat work
 293                          * unnecessarily. */
 294                         return -EALREADY;
 295         }
 296
 297         q = dns_question_new(family == AF_UNSPEC ? 2 : 1);
 298         if (!q)
 299                 return -ENOMEM;
 300
 301         if (family != AF_INET6) {
 302                 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
 303
 304                 key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_A, name);
 305                 if (!key)
 306                         return -ENOMEM;
 307
 308                 r = dns_question_add(q, key);
 309                 if (r < 0)
 310                         return r;
 311         }
 312
 313         if (family != AF_INET) {
 314                 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
 315
 316                 key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_AAAA, name);
 317                 if (!key)
 318                         return -ENOMEM;
 319
 320                 r = dns_question_add(q, key);
 321                 if (r < 0)
 322                         return r;
 323         }
 324
 325         *ret = TAKE_PTR(q);
 326
 327         return 0;
 328 }
 329
 330 int dns_question_new_reverse(DnsQuestion **ret, int family, const union in_addr_union *a) {
 331         _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
 332         _cleanup_(dns_question_unrefp) DnsQuestion *q = NULL;
 333         _cleanup_free_ char *reverse = NULL;
 334         int r;
 335
 336         assert(ret);
 337         assert(a);
 338
 339         if (!IN_SET(family, AF_INET, AF_INET6, AF_UNSPEC))
 340                 return -EAFNOSUPPORT;
 341
 342         r = dns_name_reverse(family, a, &reverse);
 343         if (r < 0)
 344                 return r;
 345
 346         q = dns_question_new(1);
 347         if (!q)
 348                 return -ENOMEM;
 349
 350         key = dns_resource_key_new_consume(DNS_CLASS_IN, DNS_TYPE_PTR, reverse);
 351         if (!key)
 352                 return -ENOMEM;
 353
 354         reverse = NULL;
 355
 356         r = dns_question_add(q, key);
 357         if (r < 0)
 358                 return r;
 359
 360         *ret = TAKE_PTR(q);
 361
 362         return 0;
 363 }
 364
 365 int dns_question_new_service(
 366                 DnsQuestion **ret,
 367                 const char *service,
 368                 const char *type,
 369                 const char *domain,
 370                 bool with_txt,
 371                 bool convert_idna) {
 372
 373         _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
 374         _cleanup_(dns_question_unrefp) DnsQuestion *q = NULL;
 375         _cleanup_free_ char *buf = NULL, *joined = NULL;
 376         const char *name;
 377         int r;
 378
 379         assert(ret);
 380
 381         /* We support three modes of invocation:
 382          *
 383          * 1. Only a domain is specified, in which case we assume a properly encoded SRV RR name, including service
 384          *    type and possibly a service name. If specified in this way we assume it's already IDNA converted if
 385          *    that's necessary.
 386          *
 387          * 2. Both service type and a domain specified, in which case a normal SRV RR is assumed, without a DNS-SD
 388          *    style prefix. In this case we'll IDNA convert the domain, if that's requested.
 389          *
 390          * 3. All three of service name, type and domain are specified, in which case a DNS-SD service is put
 391          *    together. The service name is never IDNA converted, and the domain is if requested.
 392          *
 393          * It's not supported to specify a service name without a type, or no domain name.
 394          */
 395
 396         if (!domain)
 397                 return -EINVAL;
 398
 399         if (type) {
 400                 if (convert_idna) {
 401                         r = dns_name_apply_idna(domain, &buf);
 402                         if (r < 0)
 403                                 return r;
 404                         if (r > 0)
 405                                 domain = buf;
 406                 }
 407
 408                 r = dns_service_join(service, type, domain, &joined);
 409                 if (r < 0)
 410                         return r;
 411
 412                 name = joined;
 413         } else {
 414                 if (service)
 415                         return -EINVAL;
 416
 417                 name = domain;
 418         }
 419
 420         q = dns_question_new(1 + with_txt);
 421         if (!q)
 422                 return -ENOMEM;
 423
 424         key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_SRV, name);
 425         if (!key)
 426                 return -ENOMEM;
 427
 428         r = dns_question_add(q, key);
 429         if (r < 0)
 430                 return r;
 431
 432         if (with_txt) {
 433                 dns_resource_key_unref(key);
 434                 key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_TXT, name);
 435                 if (!key)
 436                         return -ENOMEM;
 437
 438                 r = dns_question_add(q, key);
 439                 if (r < 0)
 440                         return r;
 441         }
 442
 443         *ret = TAKE_PTR(q);
 444
 445         return 0;
 446 }