src/nss-resolve/nss-resolve.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <errno.h>
   4 #include <netdb.h>
   5 #include <nss.h>
   6 #include <pthread.h>
   7 #include <stdlib.h>
   8 #include <sys/types.h>
   9 #include <unistd.h>
  10
  11 #include "env-util.h"
  12 #include "errno-util.h"
  13 #include "glyph-util.h"
  14 #include "in-addr-util.h"
  15 #include "macro.h"
  16 #include "nss-util.h"
  17 #include "resolved-def.h"
  18 #include "signal-util.h"
  19 #include "string-util.h"
  20 #include "strv.h"
  21 #include "varlink.h"
  22
  23 static JsonDispatchFlags json_dispatch_flags = 0;
  24
  25 static void setup_logging(void) {
  26         log_parse_environment_variables();
  27
  28         if (DEBUG_LOGGING)
  29                 json_dispatch_flags = JSON_LOG;
  30 }
  31
  32 static void setup_logging_once(void) {
  33         static pthread_once_t once = PTHREAD_ONCE_INIT;
  34         assert_se(pthread_once(&once, setup_logging) == 0);
  35 }
  36
  37 #define NSS_ENTRYPOINT_BEGIN                    \
  38         BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);       \
  39         setup_logging_once()
  40
  41 NSS_GETHOSTBYNAME_PROTOTYPES(resolve);
  42 NSS_GETHOSTBYADDR_PROTOTYPES(resolve);
  43
  44 static bool error_shall_fallback(const char *error_id) {
  45         /* The Varlink errors where we shall signal "please fallback" back to the NSS stack, so that some
  46          * fallback module can be loaded. (These are mostly all Varlink-internal errors, as apparently we
  47          * then were unable to even do IPC with systemd-resolved.) */
  48         return STR_IN_SET(error_id,
  49                           VARLINK_ERROR_DISCONNECTED,
  50                           VARLINK_ERROR_TIMEOUT,
  51                           VARLINK_ERROR_PROTOCOL,
  52                           VARLINK_ERROR_INTERFACE_NOT_FOUND,
  53                           VARLINK_ERROR_METHOD_NOT_FOUND,
  54                           VARLINK_ERROR_METHOD_NOT_IMPLEMENTED);
  55 }
  56
  57 static bool error_shall_try_again(const char *error_id) {
  58         /* The Varlink errors where we shall signal "can't answer now but might be able to later" back to the
  59          * NSS stack. These are all errors that indicate lack of configuration or network problems. */
  60         return STR_IN_SET(error_id,
  61                           "io.systemd.Resolve.NoNameServers",
  62                           "io.systemd.Resolve.QueryTimedOut",
  63                           "io.systemd.Resolve.MaxAttemptsReached",
  64                           "io.systemd.Resolve.NetworkDown");
  65 }
  66
  67 static int connect_to_resolved(Varlink **ret) {
  68         _cleanup_(varlink_unrefp) Varlink *link = NULL;
  69         int r;
  70
  71         r = varlink_connect_address(&link, "/run/systemd/resolve/io.systemd.Resolve");
  72         if (r < 0)
  73                 return r;
  74
  75         r = varlink_set_relative_timeout(link, SD_RESOLVED_QUERY_TIMEOUT_USEC);
  76         if (r < 0)
  77                 return r;
  78
  79         *ret = TAKE_PTR(link);
  80         return 0;
  81 }
  82
  83 static uint32_t ifindex_to_scopeid(int family, const void *a, int ifindex) {
  84         struct in6_addr in6;
  85
  86         if (family != AF_INET6 || ifindex == 0)
  87                 return 0;
  88
  89         /* Some apps can't deal with the scope ID attached to non-link-local addresses. Hence, let's suppress that. */
  90
  91         assert(sizeof(in6) == FAMILY_ADDRESS_SIZE(AF_INET6));
  92         memcpy(&in6, a, sizeof(struct in6_addr));
  93
  94         return in6_addr_is_link_local(&in6) ? ifindex : 0;
  95 }
  96
  97 static int json_dispatch_ifindex(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata) {
  98         int *ifi = ASSERT_PTR(userdata);
  99         int64_t t;
 100
 101         assert(variant);
 102
 103         if (!json_variant_is_integer(variant))
 104                 return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "JSON field '%s' is not an integer.", strna(name));
 105
 106         t = json_variant_integer(variant);
 107         if (t > INT_MAX)
 108                 return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "JSON field '%s' is out of bounds for an interface index.", strna(name));
 109
 110         *ifi = (int) t;
 111         return 0;
 112 }
 113
 114 static int json_dispatch_family(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata) {
 115         int *family = ASSERT_PTR(userdata);
 116         int64_t t;
 117
 118         assert(variant);
 119
 120         if (!json_variant_is_integer(variant))
 121                 return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "JSON field '%s' is not an integer.", strna(name));
 122
 123         t = json_variant_integer(variant);
 124         if (t < 0 || t > INT_MAX)
 125                 return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "JSON field '%s' is not a valid family.", strna(name));
 126
 127         *family = (int) t;
 128         return 0;
 129 }
 130
 131 typedef struct ResolveHostnameReply {
 132         JsonVariant *addresses;
 133         char *name;
 134         uint64_t flags;
 135 } ResolveHostnameReply;
 136
 137 static void resolve_hostname_reply_destroy(ResolveHostnameReply *p) {
 138         assert(p);
 139
 140         json_variant_unref(p->addresses);
 141         free(p->name);
 142 }
 143
 144 static const JsonDispatch resolve_hostname_reply_dispatch_table[] = {
 145         { "addresses", JSON_VARIANT_ARRAY,    json_dispatch_variant, offsetof(ResolveHostnameReply, addresses), JSON_MANDATORY },
 146         { "name",      JSON_VARIANT_STRING,   json_dispatch_string,  offsetof(ResolveHostnameReply, name),      0              },
 147         { "flags",     JSON_VARIANT_UNSIGNED, json_dispatch_uint64,  offsetof(ResolveHostnameReply, flags),     0              },
 148         {}
 149 };
 150
 151 typedef struct AddressParameters {
 152         int ifindex;
 153         int family;
 154         union in_addr_union address;
 155         size_t address_size;
 156 } AddressParameters;
 157
 158 static int json_dispatch_address(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata) {
 159         AddressParameters *p = ASSERT_PTR(userdata);
 160         union in_addr_union buf = {};
 161         JsonVariant *i;
 162         size_t n, k = 0;
 163
 164         assert(variant);
 165
 166         if (!json_variant_is_array(variant))
 167                 return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "JSON field '%s' is not an array.", strna(name));
 168
 169         n = json_variant_elements(variant);
 170         if (!IN_SET(n, 4, 16))
 171                 return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "JSON field '%s' is array of unexpected size.", strna(name));
 172
 173         JSON_VARIANT_ARRAY_FOREACH(i, variant) {
 174                 int64_t b;
 175
 176                 if (!json_variant_is_integer(i))
 177                         return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "Element %zu of JSON field '%s' is not an integer.", k, strna(name));
 178
 179                 b = json_variant_integer(i);
 180                 if (b < 0 || b > 0xff)
 181                         return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL),
 182                                         "Element %zu of JSON field '%s' is out of range 0%s255.",
 183                                         k, strna(name), special_glyph(SPECIAL_GLYPH_ELLIPSIS));
 184
 185                 buf.bytes[k++] = (uint8_t) b;
 186         }
 187
 188         p->address = buf;
 189         p->address_size = k;
 190
 191         return 0;
 192 }
 193
 194 static const JsonDispatch address_parameters_dispatch_table[] = {
 195         { "ifindex", JSON_VARIANT_INTEGER,  json_dispatch_ifindex, offsetof(AddressParameters, ifindex), 0              },
 196         { "family",  JSON_VARIANT_INTEGER,  json_dispatch_family,  offsetof(AddressParameters, family),  JSON_MANDATORY },
 197         { "address", JSON_VARIANT_ARRAY,    json_dispatch_address, 0,                                    JSON_MANDATORY },
 198         {}
 199 };
 200
 201 static uint64_t query_flag(
 202                 const char *name,
 203                 const int value,
 204                 uint64_t flag) {
 205         int r;
 206
 207         r = getenv_bool_secure(name);
 208         if (r >= 0)
 209                 return r == value ? flag : 0;
 210         if (r != -ENXIO)
 211                 log_debug_errno(r, "Failed to parse $%s, ignoring.", name);
 212         return 0;
 213 }
 214
 215 static uint64_t query_flags(void) {
 216         /* Allow callers to turn off validation, synthetization, caching, etc., when we resolve via
 217          * nss-resolve. */
 218         return  query_flag("SYSTEMD_NSS_RESOLVE_VALIDATE", 0, SD_RESOLVED_NO_VALIDATE) |
 219                 query_flag("SYSTEMD_NSS_RESOLVE_SYNTHESIZE", 0, SD_RESOLVED_NO_SYNTHESIZE) |
 220                 query_flag("SYSTEMD_NSS_RESOLVE_CACHE", 0, SD_RESOLVED_NO_CACHE) |
 221                 query_flag("SYSTEMD_NSS_RESOLVE_ZONE", 0, SD_RESOLVED_NO_ZONE) |
 222                 query_flag("SYSTEMD_NSS_RESOLVE_TRUST_ANCHOR", 0, SD_RESOLVED_NO_TRUST_ANCHOR) |
 223                 query_flag("SYSTEMD_NSS_RESOLVE_NETWORK", 0, SD_RESOLVED_NO_NETWORK);
 224 }
 225
 226 enum nss_status _nss_resolve_gethostbyname4_r(
 227                 const char *name,
 228                 struct gaih_addrtuple **pat,
 229                 char *buffer, size_t buflen,
 230                 int *errnop, int *h_errnop,
 231                 int32_t *ttlp) {
 232
 233         _cleanup_(varlink_unrefp) Varlink *link = NULL;
 234         _cleanup_(json_variant_unrefp) JsonVariant *cparams = NULL;
 235         _cleanup_(resolve_hostname_reply_destroy) ResolveHostnameReply p = {};
 236         JsonVariant *rparams, *entry;
 237         int r;
 238
 239         PROTECT_ERRNO;
 240         NSS_ENTRYPOINT_BEGIN;
 241
 242         assert(name);
 243         assert(pat);
 244         assert(buffer);
 245         assert(errnop);
 246         assert(h_errnop);
 247
 248         r = connect_to_resolved(&link);
 249         if (r < 0)
 250                 goto fail;
 251
 252         r = json_build(&cparams, JSON_BUILD_OBJECT(
 253                                        JSON_BUILD_PAIR("name", JSON_BUILD_STRING(name)),
 254                                        JSON_BUILD_PAIR("flags", JSON_BUILD_UNSIGNED(query_flags()))));
 255         if (r < 0)
 256                 goto fail;
 257
 258         /* Return NSS_STATUS_UNAVAIL when communication with systemd-resolved fails, allowing falling
 259          * back to other nss modules. Treat all other error conditions as NOTFOUND. This includes
 260          * DNSSEC errors and suchlike. (We don't use UNAVAIL in this case so that the nsswitch.conf
 261          * configuration can distinguish such executed but negative replies from complete failure to
 262          * talk to resolved). */
 263         const char *error_id;
 264         r = varlink_call(link, "io.systemd.Resolve.ResolveHostname", cparams, &rparams, &error_id, NULL);
 265         if (r < 0)
 266                 goto fail;
 267         if (!isempty(error_id)) {
 268                 if (error_shall_try_again(error_id))
 269                         goto try_again;
 270                 if (error_shall_fallback(error_id))
 271                         goto fail;
 272                 goto not_found;
 273         }
 274
 275         r = json_dispatch(rparams, resolve_hostname_reply_dispatch_table, NULL, json_dispatch_flags, &p);
 276         if (r < 0)
 277                 goto fail;
 278         if (json_variant_is_blank_object(p.addresses))
 279                 goto not_found;
 280
 281         size_t n_addresses = 0;
 282         JSON_VARIANT_ARRAY_FOREACH(entry, p.addresses) {
 283                 AddressParameters q = {};
 284
 285                 r = json_dispatch(entry, address_parameters_dispatch_table, NULL, json_dispatch_flags, &q);
 286                 if (r < 0)
 287                         goto fail;
 288
 289                 if (!IN_SET(q.family, AF_INET, AF_INET6))
 290                         continue;
 291
 292                 if (q.address_size != FAMILY_ADDRESS_SIZE(q.family)) {
 293                         r = -EINVAL;
 294                         goto fail;
 295                 }
 296
 297                 n_addresses++;
 298         }
 299
 300         const char *canonical = p.name ?: name;
 301         size_t l = strlen(canonical);
 302         size_t idx, ms = ALIGN(l+1) + ALIGN(sizeof(struct gaih_addrtuple)) * n_addresses;
 303
 304         if (buflen < ms) {
 305                 UNPROTECT_ERRNO;
 306                 *errnop = ERANGE;
 307                 *h_errnop = NETDB_INTERNAL;
 308                 return NSS_STATUS_TRYAGAIN;
 309         }
 310
 311         /* First, append name */
 312         char *r_name = buffer;
 313         memcpy(r_name, canonical, l + 1);
 314         idx = ALIGN(l + 1);
 315
 316         /* Second, append addresses */
 317         struct gaih_addrtuple *r_tuple = NULL,
 318                 *r_tuple_first = (struct gaih_addrtuple*) (buffer + idx);
 319
 320         JSON_VARIANT_ARRAY_FOREACH(entry, p.addresses) {
 321                 AddressParameters q = {};
 322
 323                 r = json_dispatch(entry, address_parameters_dispatch_table, NULL, json_dispatch_flags, &q);
 324                 if (r < 0)
 325                         goto fail;
 326
 327                 if (!IN_SET(q.family, AF_INET, AF_INET6))
 328                         continue;
 329
 330                 r_tuple = (struct gaih_addrtuple*) (buffer + idx);
 331                 r_tuple->next = (struct gaih_addrtuple*) ((char*) r_tuple + ALIGN(sizeof(struct gaih_addrtuple)));
 332                 r_tuple->name = r_name;
 333                 r_tuple->family = q.family;
 334                 r_tuple->scopeid = ifindex_to_scopeid(q.family, &q.address, q.ifindex);
 335                 memcpy(r_tuple->addr, &q.address, q.address_size);
 336
 337                 idx += ALIGN(sizeof(struct gaih_addrtuple));
 338         }
 339
 340         assert(r_tuple);  /* We had at least one address, so r_tuple must be set */
 341         r_tuple->next = NULL;  /* Override last next pointer */
 342
 343         assert(idx == ms);
 344
 345         if (*pat)
 346                 **pat = *r_tuple_first;
 347         else
 348                 *pat = r_tuple_first;
 349
 350         if (ttlp)
 351                 *ttlp = 0;
 352
 353         /* Explicitly reset both *h_errnop and h_errno to work around
 354          * https://bugzilla.redhat.com/show_bug.cgi?id=1125975 */
 355         *h_errnop = NETDB_SUCCESS;
 356         h_errno = 0;
 357
 358         return NSS_STATUS_SUCCESS;
 359
 360 fail:
 361         UNPROTECT_ERRNO;
 362         *errnop = -r;
 363         *h_errnop = NO_RECOVERY;
 364         return NSS_STATUS_UNAVAIL;
 365
 366 not_found:
 367         *h_errnop = HOST_NOT_FOUND;
 368         return NSS_STATUS_NOTFOUND;
 369
 370 try_again:
 371         UNPROTECT_ERRNO;
 372         *errnop = -r;
 373         *h_errnop = TRY_AGAIN;
 374         return NSS_STATUS_TRYAGAIN;
 375 }
 376
 377 enum nss_status _nss_resolve_gethostbyname3_r(
 378                 const char *name,
 379                 int af,
 380                 struct hostent *result,
 381                 char *buffer, size_t buflen,
 382                 int *errnop, int *h_errnop,
 383                 int32_t *ttlp,
 384                 char **canonp) {
 385
 386         _cleanup_(varlink_unrefp) Varlink *link = NULL;
 387         _cleanup_(json_variant_unrefp) JsonVariant *cparams = NULL;
 388         _cleanup_(resolve_hostname_reply_destroy) ResolveHostnameReply p = {};
 389         JsonVariant *rparams, *entry;
 390         int r;
 391
 392         PROTECT_ERRNO;
 393         NSS_ENTRYPOINT_BEGIN;
 394
 395         assert(name);
 396         assert(result);
 397         assert(buffer);
 398         assert(errnop);
 399         assert(h_errnop);
 400
 401         if (af == AF_UNSPEC)
 402                 af = AF_INET;
 403
 404         if (!IN_SET(af, AF_INET, AF_INET6)) {
 405                 r = -EAFNOSUPPORT;
 406                 goto fail;
 407         }
 408
 409         r = connect_to_resolved(&link);
 410         if (r < 0)
 411                 goto fail;
 412
 413         r = json_build(&cparams, JSON_BUILD_OBJECT(JSON_BUILD_PAIR("name", JSON_BUILD_STRING(name)),
 414                                                    JSON_BUILD_PAIR("family", JSON_BUILD_INTEGER(af)),
 415                                                    JSON_BUILD_PAIR("flags", JSON_BUILD_UNSIGNED(query_flags()))));
 416         if (r < 0)
 417                 goto fail;
 418
 419         const char *error_id;
 420         r = varlink_call(link, "io.systemd.Resolve.ResolveHostname", cparams, &rparams, &error_id, NULL);
 421         if (r < 0)
 422                 goto fail;
 423         if (!isempty(error_id)) {
 424                 if (error_shall_try_again(error_id))
 425                         goto try_again;
 426                 if (error_shall_fallback(error_id))
 427                         goto fail;
 428                 goto not_found;
 429         }
 430
 431         r = json_dispatch(rparams, resolve_hostname_reply_dispatch_table, NULL, json_dispatch_flags, &p);
 432         if (r < 0)
 433                 goto fail;
 434         if (json_variant_is_blank_object(p.addresses))
 435                 goto not_found;
 436
 437         size_t n_addresses = 0;
 438         JSON_VARIANT_ARRAY_FOREACH(entry, p.addresses) {
 439                 AddressParameters q = {};
 440
 441                 r = json_dispatch(entry, address_parameters_dispatch_table, NULL, json_dispatch_flags, &q);
 442                 if (r < 0)
 443                         goto fail;
 444
 445                 if (!IN_SET(q.family, AF_INET, AF_INET6))
 446                         continue;
 447
 448                 if (q.address_size != FAMILY_ADDRESS_SIZE(q.family)) {
 449                         r = -EINVAL;
 450                         goto fail;
 451                 }
 452
 453                 n_addresses++;
 454         }
 455
 456         const char *canonical = p.name ?: name;
 457
 458         size_t alen = FAMILY_ADDRESS_SIZE(af);
 459         size_t l = strlen(canonical);
 460
 461         size_t idx, ms = ALIGN(l + 1) + n_addresses * ALIGN(alen) + (n_addresses + 2) * sizeof(char*);
 462
 463         if (buflen < ms) {
 464                 UNPROTECT_ERRNO;
 465                 *errnop = ERANGE;
 466                 *h_errnop = NETDB_INTERNAL;
 467                 return NSS_STATUS_TRYAGAIN;
 468         }
 469
 470         /* First, append name */
 471         char *r_name = buffer;
 472         memcpy(r_name, canonical, l+1);
 473         idx = ALIGN(l+1);
 474
 475         /* Second, create empty aliases array */
 476         char *r_aliases = buffer + idx;
 477         ((char**) r_aliases)[0] = NULL;
 478         idx += sizeof(char*);
 479
 480         /* Third, append addresses */
 481         char *r_addr = buffer + idx;
 482
 483         size_t i = 0;
 484         JSON_VARIANT_ARRAY_FOREACH(entry, p.addresses) {
 485                 AddressParameters q = {};
 486
 487                 r = json_dispatch(entry, address_parameters_dispatch_table, NULL, json_dispatch_flags, &q);
 488                 if (r < 0)
 489                         goto fail;
 490
 491                 if (q.family != af)
 492                         continue;
 493
 494                 if (q.address_size != alen) {
 495                         r = -EINVAL;
 496                         goto fail;
 497                 }
 498
 499                 memcpy(r_addr + i*ALIGN(alen), &q.address, alen);
 500                 i++;
 501         }
 502
 503         assert(i == n_addresses);
 504         idx += n_addresses * ALIGN(alen);
 505
 506         /* Fourth, append address pointer array */
 507         char *r_addr_list = buffer + idx;
 508         for (i = 0; i < n_addresses; i++)
 509                 ((char**) r_addr_list)[i] = r_addr + i*ALIGN(alen);
 510
 511         ((char**) r_addr_list)[i] = NULL;
 512         idx += (n_addresses + 1) * sizeof(char*);
 513
 514         assert(idx == ms);
 515
 516         result->h_name = r_name;
 517         result->h_aliases = (char**) r_aliases;
 518         result->h_addrtype = af;
 519         result->h_length = alen;
 520         result->h_addr_list = (char**) r_addr_list;
 521
 522         if (ttlp)
 523                 *ttlp = 0;
 524
 525         if (canonp)
 526                 *canonp = r_name;
 527
 528         /* Explicitly reset both *h_errnop and h_errno to work around
 529          * https://bugzilla.redhat.com/show_bug.cgi?id=1125975 */
 530         *h_errnop = NETDB_SUCCESS;
 531         h_errno = 0;
 532
 533         return NSS_STATUS_SUCCESS;
 534
 535 fail:
 536         UNPROTECT_ERRNO;
 537         *errnop = -r;
 538         *h_errnop = NO_RECOVERY;
 539         return NSS_STATUS_UNAVAIL;
 540
 541 not_found:
 542         *h_errnop = HOST_NOT_FOUND;
 543         return NSS_STATUS_NOTFOUND;
 544
 545 try_again:
 546         UNPROTECT_ERRNO;
 547         *errnop = -r;
 548         *h_errnop = TRY_AGAIN;
 549         return NSS_STATUS_TRYAGAIN;
 550 }
 551
 552 typedef struct ResolveAddressReply {
 553         JsonVariant *names;
 554         uint64_t flags;
 555 } ResolveAddressReply;
 556
 557 static void resolve_address_reply_destroy(ResolveAddressReply *p) {
 558         assert(p);
 559
 560         json_variant_unref(p->names);
 561 }
 562
 563 static const JsonDispatch resolve_address_reply_dispatch_table[] = {
 564         { "names", JSON_VARIANT_ARRAY,    json_dispatch_variant, offsetof(ResolveAddressReply, names), JSON_MANDATORY },
 565         { "flags", JSON_VARIANT_UNSIGNED, json_dispatch_uint64,  offsetof(ResolveAddressReply, flags), 0              },
 566         {}
 567 };
 568
 569 typedef struct NameParameters {
 570         int ifindex;
 571         char *name;
 572 } NameParameters;
 573
 574 static void name_parameters_destroy(NameParameters *p) {
 575         assert(p);
 576
 577         free(p->name);
 578 }
 579
 580 static const JsonDispatch name_parameters_dispatch_table[] = {
 581         { "ifindex", JSON_VARIANT_INTEGER, json_dispatch_ifindex, offsetof(NameParameters, ifindex), 0              },
 582         { "name",    JSON_VARIANT_STRING,  json_dispatch_string,  offsetof(NameParameters, name),    JSON_MANDATORY },
 583         {}
 584 };
 585
 586 enum nss_status _nss_resolve_gethostbyaddr2_r(
 587                 const void* addr, socklen_t len,
 588                 int af,
 589                 struct hostent *result,
 590                 char *buffer, size_t buflen,
 591                 int *errnop, int *h_errnop,
 592                 int32_t *ttlp) {
 593
 594         _cleanup_(varlink_unrefp) Varlink *link = NULL;
 595         _cleanup_(json_variant_unrefp) JsonVariant *cparams = NULL;
 596         _cleanup_(resolve_address_reply_destroy) ResolveAddressReply p = {};
 597         JsonVariant *rparams, *entry;
 598         int r;
 599
 600         PROTECT_ERRNO;
 601         NSS_ENTRYPOINT_BEGIN;
 602
 603         assert(addr);
 604         assert(result);
 605         assert(buffer);
 606         assert(errnop);
 607         assert(h_errnop);
 608
 609         if (!IN_SET(af, AF_INET, AF_INET6)) {
 610                 UNPROTECT_ERRNO;
 611                 *errnop = EAFNOSUPPORT;
 612                 *h_errnop = NO_DATA;
 613                 return NSS_STATUS_UNAVAIL;
 614         }
 615
 616         if (len != FAMILY_ADDRESS_SIZE(af)) {
 617                 r = -EINVAL;
 618                 goto fail;
 619         }
 620
 621         r = connect_to_resolved(&link);
 622         if (r < 0)
 623                 goto fail;
 624
 625         r = json_build(&cparams, JSON_BUILD_OBJECT(JSON_BUILD_PAIR("address", JSON_BUILD_BYTE_ARRAY(addr, len)),
 626                                                    JSON_BUILD_PAIR("family", JSON_BUILD_INTEGER(af)),
 627                                                    JSON_BUILD_PAIR("flags", JSON_BUILD_UNSIGNED(query_flags()))));
 628         if (r < 0)
 629                 goto fail;
 630
 631         const char* error_id;
 632         r = varlink_call(link, "io.systemd.Resolve.ResolveAddress", cparams, &rparams, &error_id, NULL);
 633         if (r < 0)
 634                 goto fail;
 635         if (!isempty(error_id)) {
 636                 if (error_shall_try_again(error_id))
 637                         goto try_again;
 638                 if (error_shall_fallback(error_id))
 639                         goto fail;
 640                 goto not_found;
 641         }
 642
 643         r = json_dispatch(rparams, resolve_address_reply_dispatch_table, NULL, json_dispatch_flags, &p);
 644         if (r < 0)
 645                 goto fail;
 646         if (json_variant_is_blank_object(p.names))
 647                 goto not_found;
 648
 649         size_t ms = 0, idx;
 650
 651         JSON_VARIANT_ARRAY_FOREACH(entry, p.names) {
 652                 _cleanup_(name_parameters_destroy) NameParameters q = {};
 653
 654                 r = json_dispatch(entry, name_parameters_dispatch_table, NULL, json_dispatch_flags, &q);
 655                 if (r < 0)
 656                         goto fail;
 657
 658                 ms += ALIGN(strlen(q.name) + 1);
 659         }
 660
 661         size_t n_names = json_variant_elements(p.names);
 662         ms += ALIGN(len) +                    /* the address */
 663               2 * sizeof(char*) +             /* pointer to the address, plus trailing NULL */
 664               n_names * sizeof(char*);        /* pointers to aliases, plus trailing NULL */
 665
 666         if (buflen < ms) {
 667                 UNPROTECT_ERRNO;
 668                 *errnop = ERANGE;
 669                 *h_errnop = NETDB_INTERNAL;
 670                 return NSS_STATUS_TRYAGAIN;
 671         }
 672
 673         /* First, place address */
 674         char *r_addr = buffer;
 675         memcpy(r_addr, addr, len);
 676         idx = ALIGN(len);
 677
 678         /* Second, place address list */
 679         char *r_addr_list = buffer + idx;
 680         ((char**) r_addr_list)[0] = r_addr;
 681         ((char**) r_addr_list)[1] = NULL;
 682         idx += sizeof(char*) * 2;
 683
 684         /* Third, reserve space for the aliases array, plus trailing NULL */
 685         char *r_aliases = buffer + idx;
 686         idx += sizeof(char*) * n_names;
 687
 688         /* Fourth, place aliases */
 689         char *r_name = buffer + idx;
 690
 691         size_t i = 0;
 692         JSON_VARIANT_ARRAY_FOREACH(entry, p.names) {
 693                 _cleanup_(name_parameters_destroy) NameParameters q = {};
 694
 695                 r = json_dispatch(entry, name_parameters_dispatch_table, NULL, json_dispatch_flags, &q);
 696                 if (r < 0)
 697                         goto fail;
 698
 699                 size_t l = strlen(q.name);
 700                 char *z = buffer + idx;
 701                 memcpy(z, q.name, l + 1);
 702
 703                 if (i > 0)
 704                         ((char**) r_aliases)[i - 1] = z;
 705                 i++;
 706
 707                 idx += ALIGN(l + 1);
 708         }
 709         ((char**) r_aliases)[n_names - 1] = NULL;
 710
 711         assert(idx == ms);
 712
 713         result->h_name = r_name;
 714         result->h_aliases = (char**) r_aliases;
 715         result->h_addrtype = af;
 716         result->h_length = len;
 717         result->h_addr_list = (char**) r_addr_list;
 718
 719         if (ttlp)
 720                 *ttlp = 0;
 721
 722         /* Explicitly reset both *h_errnop and h_errno to work around
 723          * https://bugzilla.redhat.com/show_bug.cgi?id=1125975 */
 724         *h_errnop = NETDB_SUCCESS;
 725         h_errno = 0;
 726
 727         return NSS_STATUS_SUCCESS;
 728
 729 fail:
 730         UNPROTECT_ERRNO;
 731         *errnop = -r;
 732         *h_errnop = NO_RECOVERY;
 733         return NSS_STATUS_UNAVAIL;
 734
 735 not_found:
 736         *h_errnop = HOST_NOT_FOUND;
 737         return NSS_STATUS_NOTFOUND;
 738
 739 try_again:
 740         UNPROTECT_ERRNO;
 741         *errnop = -r;
 742         *h_errnop = TRY_AGAIN;
 743         return NSS_STATUS_TRYAGAIN;
 744 }
 745
 746 NSS_GETHOSTBYNAME_FALLBACKS(resolve);
 747 NSS_GETHOSTBYADDR_FALLBACKS(resolve);