src/gns/gnunet-service-gns_resolver.c

   1 /*
   2      This file is part of GNUnet.
   3      (C) 2011-2013 Christian Grothoff (and other contributing authors)
   4
   5      GNUnet is free software; you can redistribute it and/or modify
   6      it under the terms of the GNU General Public License as published
   7      by the Free Software Foundation; either version 3, or (at your
   8      option) any later version.
   9
  10      GNUnet is distributed in the hope that it will be useful, but
  11      WITHOUT ANY WARRANTY; without even the implied warranty of
  12      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13      General Public License for more details.
  14
  15      You should have received a copy of the GNU General Public License
  16      along with GNUnet; see the file COPYING.  If not, write to the
  17      Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18      Boston, MA 02111-1307, USA.
  19 */
  20
  21 /**
  22  * @file gns/gnunet-service-gns_resolver.c
  23  * @brief GNU Name System resolver logic
  24  * @author Martin Schanzenbach
  25  * @author Christian Grothoff
  26  *
  27  * TODO:
  28  * - GNS: handle special SRV names --- no delegation, direct lookup;
  29  *        can likely be done in 'resolver_lookup_get_next_label'. (#3003)
  30  * - revocation checks (use CORE-level broadcasts!), (#3004)
  31  * - DNAME support (#3005)
  32  */
  33 #include "platform.h"
  34 #include "gnunet_util_lib.h"
  35 #include "gnunet_dnsstub_lib.h"
  36 #include "gnunet_dht_service.h"
  37 #include "gnunet_namestore_service.h"
  38 #include "gnunet_dns_service.h"
  39 #include "gnunet_resolver_service.h"
  40 #include "gnunet_dnsparser_lib.h"
  41 #include "gnunet_gns_service.h"
  42 #include "gns.h"
  43 #include "gnunet-service-gns_resolver.h"
  44 #include "gnunet-service-gns_shorten.h"
  45 #include "gnunet_vpn_service.h"
  46
  47
  48 /**
  49  * Default DHT timeout for lookups.
  50  */
  51 #define DHT_LOOKUP_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 60)
  52
  53 /**
  54  * Default timeout for DNS lookups.
  55  */
  56 #define DNS_LOOKUP_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)
  57
  58 /**
  59  * Default timeout for VPN redirections.
  60  */
  61 #define VPN_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 30)
  62
  63 /**
  64  * DHT replication level
  65  */
  66 #define DHT_GNS_REPLICATION_LEVEL 5
  67
  68 /**
  69  * How deep do we allow recursions to go before we abort?
  70  */
  71 #define MAX_RECURSION 256
  72
  73
  74 /**
  75  * DLL to hold the authority chain we had to pass in the resolution
  76  * process.
  77  */
  78 struct AuthorityChain
  79 {
  80   /**
  81    * This is a DLL.
  82    */
  83   struct AuthorityChain *prev;
  84
  85   /**
  86    * This is a DLL.
  87    */
  88   struct AuthorityChain *next;
  89
  90   /**
  91    * Resolver handle this entry in the chain belongs to.
  92    */
  93   struct GNS_ResolverHandle *rh;
  94
  95   /**
  96    * label/name corresponding to the authority
  97    */
  98   char *label;
  99
 100   /**
 101    * #GNUNET_YES if the authority was a GNS authority,
 102    * #GNUNET_NO if the authority was a DNS authority.
 103    */
 104   int gns_authority;
 105
 106   /**
 107    * Information about the resolver authority for this label.
 108    */
 109   union
 110   {
 111
 112     /**
 113      * The zone of the GNS authority
 114      */
 115     struct GNUNET_CRYPTO_EccPublicSignKey gns_authority;
 116
 117     struct
 118     {
 119       /**
 120        * Domain of the DNS resolver that is the authority.
 121        * (appended to construct the DNS name to resolve;
 122        * this is NOT the DNS name of the DNS server!).
 123        */
 124       char name[GNUNET_DNSPARSER_MAX_NAME_LENGTH + 1];
 125
 126       /**
 127        * IP address of the DNS resolver that is authoritative.
 128        * (this implementation currently only supports one
 129        * IP at a time).
 130        */
 131       struct sockaddr_storage dns_ip;
 132
 133     } dns_authority;
 134
 135   } authority_info;
 136
 137 };
 138
 139
 140 /**
 141  * A result we got from DNS.
 142  */
 143 struct DnsResult
 144 {
 145
 146   /**
 147    * Kept in DLL.
 148    */
 149   struct DnsResult *next;
 150
 151   /**
 152    * Kept in DLL.
 153    */
 154   struct DnsResult *prev;
 155
 156   /**
 157    * Binary value stored in the DNS record (appended to this struct)
 158    */
 159   const void *data;
 160
 161   /**
 162    * Expiration time for the DNS record, 0 if we didn't
 163    * get anything useful (i.e. 'gethostbyname' was used).
 164    */
 165   uint64_t expiration_time;
 166
 167   /**
 168    * Number of bytes in 'data'.
 169    */
 170   size_t data_size;
 171
 172   /**
 173    * Type of the GNS/DNS record.
 174    */
 175   uint32_t record_type;
 176
 177 };
 178
 179
 180 /**
 181  * Closure for #vpn_allocation_cb.
 182  */
 183 struct VpnContext
 184 {
 185
 186   /**
 187    * Which resolution process are we processing.
 188    */
 189   struct GNS_ResolverHandle *rh;
 190
 191   /**
 192    * Handle to the VPN request that we were performing.
 193    */
 194   struct GNUNET_VPN_RedirectionRequest *vpn_request;
 195
 196   /**
 197    * Number of records serialized in 'rd_data'.
 198    */
 199   unsigned int rd_count;
 200
 201   /**
 202    * Serialized records.
 203    */
 204   char *rd_data;
 205
 206   /**
 207    * Number of bytes in 'rd_data'.
 208    */
 209   size_t rd_data_size;
 210 };
 211
 212
 213 /**
 214  * Handle to a currenty pending resolution.  On result (positive or
 215  * negative) the #GNS_ResultProcessor is called.
 216  */
 217 struct GNS_ResolverHandle
 218 {
 219
 220   /**
 221    * DLL
 222    */
 223   struct GNS_ResolverHandle *next;
 224
 225   /**
 226    * DLL
 227    */
 228   struct GNS_ResolverHandle *prev;
 229
 230   /**
 231    * The top-level GNS authoritative zone to query
 232    */
 233   struct GNUNET_CRYPTO_EccPublicSignKey authority_zone;
 234
 235   /**
 236    * called when resolution phase finishes
 237    */
 238   GNS_ResultProcessor proc;
 239
 240   /**
 241    * closure passed to proc
 242    */
 243   void* proc_cls;
 244
 245   /**
 246    * Handle for DHT lookups. should be NULL if no lookups are in progress
 247    */
 248   struct GNUNET_DHT_GetHandle *get_handle;
 249
 250   /**
 251    * Handle to a VPN request, NULL if none is active.
 252    */
 253   struct VpnContext *vpn_ctx;
 254
 255   /**
 256    * Socket for a DNS request, NULL if none is active.
 257    */
 258   struct GNUNET_DNSSTUB_RequestSocket *dns_request;
 259
 260   /**
 261    * Handle for standard DNS resolution, NULL if none is active.
 262    */
 263   struct GNUNET_RESOLVER_RequestHandle *std_resolve;
 264
 265   /**
 266    * Pending Namestore task
 267    */
 268   struct GNUNET_NAMESTORE_QueueEntry *namestore_qe;
 269
 270   /**
 271    * Heap node associated with this lookup.  Used to limit number of
 272    * concurrent requests.
 273    */
 274   struct GNUNET_CONTAINER_HeapNode *dht_heap_node;
 275
 276   /**
 277    * DLL to store the authority chain
 278    */
 279   struct AuthorityChain *ac_head;
 280
 281   /**
 282    * DLL to store the authority chain
 283    */
 284   struct AuthorityChain *ac_tail;
 285
 286   /**
 287    * Private key of the shorten zone, NULL to not shorten.
 288    */
 289   struct GNUNET_CRYPTO_EccPrivateKey *shorten_key;
 290
 291   /**
 292    * ID of a task associated with the resolution process.
 293    */
 294   GNUNET_SCHEDULER_TaskIdentifier task_id;
 295
 296   /**
 297    * The name to resolve
 298    */
 299   char *name;
 300
 301   /**
 302    * DLL of results we got from DNS.
 303    */
 304   struct DnsResult *dns_result_head;
 305
 306   /**
 307    * DLL of results we got from DNS.
 308    */
 309   struct DnsResult *dns_result_tail;
 310
 311   /**
 312    * Current offset in 'name' where we are resolving.
 313    */
 314   size_t name_resolution_pos;
 315
 316   /**
 317    * Use only cache
 318    */
 319   int only_cached;
 320
 321   /**
 322    * Desired type for the resolution.
 323    */
 324   int record_type;
 325
 326   /**
 327    * We increment the loop limiter for each step in a recursive
 328    * resolution.  If it passes our threshold (i.e. due to
 329    * self-recursion in the resolution, i.e CNAME fun), we stop.
 330    */
 331   unsigned int loop_limiter;
 332
 333 };
 334
 335
 336 /**
 337  * Our handle to the namestore service
 338  */
 339 static struct GNUNET_NAMESTORE_Handle *namestore_handle;
 340
 341 /**
 342  * Our handle to the vpn service
 343  */
 344 static struct GNUNET_VPN_Handle *vpn_handle;
 345
 346 /**
 347  * Resolver handle to the dht
 348  */
 349 static struct GNUNET_DHT_Handle *dht_handle;
 350
 351 /**
 352  * Handle to perform DNS lookups.
 353  */
 354 static struct GNUNET_DNSSTUB_Context *dns_handle;
 355
 356 /**
 357  * Heap for limiting parallel DHT lookups
 358  */
 359 static struct GNUNET_CONTAINER_Heap *dht_lookup_heap;
 360
 361 /**
 362  * Maximum amount of parallel queries to the DHT
 363  */
 364 static unsigned long long max_allowed_background_queries;
 365
 366 /**
 367  * Head of resolver lookup list
 368  */
 369 static struct GNS_ResolverHandle *rlh_head;
 370
 371 /**
 372  * Tail of resolver lookup list
 373  */
 374 static struct GNS_ResolverHandle *rlh_tail;
 375
 376 /**
 377  * Global configuration.
 378  */
 379 static const struct GNUNET_CONFIGURATION_Handle *cfg;
 380
 381
 382 /**
 383  * Check if name is in srv format (_x._y.xxx)
 384  *
 385  * @param name
 386  * @return #GNUNET_YES if true
 387  */
 388 static int
 389 is_srv (const char *name)
 390 {
 391   char *ndup;
 392   int ret;
 393
 394   if (*name != '_')
 395     return GNUNET_NO;
 396   if (NULL == strstr (name, "._"))
 397     return GNUNET_NO;
 398   ret = GNUNET_YES;
 399   ndup = GNUNET_strdup (name);
 400   strtok (ndup, ".");
 401   if (NULL == strtok (NULL, "."))
 402     ret = GNUNET_NO;
 403   if (NULL == strtok (NULL, "."))
 404     ret = GNUNET_NO;
 405   if (NULL != strtok (NULL, "."))
 406     ret = GNUNET_NO;
 407   GNUNET_free (ndup);
 408   return ret;
 409 }
 410
 411
 412 /**
 413  * Determine if this name is canonical (is a legal name in a zone, without delegation);
 414  * note that we do not test that the name does not contain illegal characters, we only
 415  * test for delegation.  Note that service records (i.e. _foo._srv) are canonical names
 416  * even though they consist of multiple labels.
 417  *
 418  * Examples:
 419  * a.b.gnu  = not canonical
 420  * a         = canonical
 421  * _foo._srv = canonical
 422  * _f.bar    = not canonical
 423  *
 424  * @param name the name to test
 425  * @return #GNUNET_YES if canonical
 426  */
 427 static int
 428 is_canonical (const char *name)
 429 {
 430   const char *pos;
 431   const char *dot;
 432
 433   if (NULL == strchr (name, '.'))
 434     return GNUNET_YES;
 435   if ('_' != name[0])
 436     return GNUNET_NO;
 437   pos = &name[1];
 438   while (NULL != (dot = strchr (pos, '.')))
 439     if ('_' != dot[1])
 440       return GNUNET_NO;
 441     else
 442       pos = dot + 1;
 443   return GNUNET_YES;
 444 }
 445
 446 /* ************************** Resolution **************************** */
 447
 448 /**
 449  * Exands a name ending in .+ with the zone of origin.
 450  *
 451  * @param rh resolution context
 452  * @param name name to modify (to be free'd or returned)
 453  * @return updated name
 454  */
 455 static char *
 456 translate_dot_plus (struct GNS_ResolverHandle *rh,
 457                     char *name)
 458 {
 459   char *ret;
 460   size_t s_len = strlen (name);
 461
 462   if (0 != strcmp (&name[s_len - 2],
 463                    ".+"))
 464     return name; /* did not end in ".+" */
 465   GNUNET_assert (GNUNET_YES == rh->ac_tail->gns_authority);
 466   GNUNET_asprintf (&ret,
 467                    "%.*s.%s",
 468                    (int) (s_len - 2),
 469                    name,
 470                    GNUNET_NAMESTORE_pkey_to_zkey (&rh->ac_tail->authority_info.gns_authority));
 471   GNUNET_free (name);
 472   return ret;
 473 }
 474
 475
 476 /**
 477  * Task scheduled to asynchronously fail a resolution.
 478  *
 479  * @param cls the 'struct GNS_ResolverHandle' of the resolution to fail
 480  * @param tc task context
 481  */
 482 static void
 483 fail_resolution (void *cls,
 484                  const struct GNUNET_SCHEDULER_TaskContext *tc)
 485 {
 486   struct GNS_ResolverHandle *rh = cls;
 487
 488   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
 489   rh->proc (rh->proc_cls, 0, NULL);
 490   GNS_resolver_lookup_cancel (rh);
 491 }
 492
 493
 494 #if (defined WINDOWS) || (defined DARWIN)
 495 /* Don't have this on W32, here's a naive implementation
 496  * Was somehow removed on OS X ...  */
 497 void *
 498 memrchr (const void *s, int c, size_t n)
 499 {
 500   size_t i;
 501   unsigned char *ucs = (unsigned char *) s;
 502
 503   for (i = n - 1; i >= 0; i--)
 504     if (ucs[i] == c)
 505       return (void *) &ucs[i];
 506   return NULL;
 507 }
 508 #endif
 509
 510
 511 /**
 512  * Get the next, rightmost label from the name that we are trying to resolve,
 513  * and update the resolution position accordingly.
 514  *
 515  * @param rh handle to the resolution operation to get the next label from
 516  * @return NULL if there are no more labels
 517  */
 518 static char *
 519 resolver_lookup_get_next_label (struct GNS_ResolverHandle *rh)
 520 {
 521   const char *rp;
 522   const char *dot;
 523   size_t len;
 524
 525   if (0 == rh->name_resolution_pos)
 526     return NULL;
 527   dot = memrchr (rh->name, (int) '.', rh->name_resolution_pos);
 528   if (NULL == dot)
 529   {
 530     /* done, this was the last one */
 531     len = rh->name_resolution_pos;
 532     rp = rh->name;
 533     rh->name_resolution_pos = 0;
 534   }
 535   else
 536   {
 537     /* advance by one label */
 538     len = rh->name_resolution_pos - (dot - rh->name) - 1;
 539     rp = dot + 1;
 540     rh->name_resolution_pos = dot - rh->name;
 541   }
 542   return GNUNET_strndup (rp, len);
 543 }
 544
 545
 546 /**
 547  * Gives the cummulative result obtained to the callback and clean up the request.
 548  *
 549  * @param rh resolution process that has culminated in a result
 550  */
 551 static void
 552 transmit_lookup_dns_result (struct GNS_ResolverHandle *rh)
 553 {
 554   struct DnsResult *pos;
 555   unsigned int n;
 556   unsigned int i;
 557
 558   n = 0;
 559   for (pos = rh->dns_result_head; NULL != pos; pos = pos->next)
 560     n++;
 561   {
 562     struct GNUNET_NAMESTORE_RecordData rd[n];
 563
 564     i = 0;
 565     for (pos = rh->dns_result_head; NULL != pos; pos = pos->next)
 566     {
 567       rd[i].data = pos->data;
 568       rd[i].data_size = pos->data_size;
 569       rd[i].record_type = pos->record_type;
 570       if (0 == pos->expiration_time)
 571       {
 572         rd[i].flags = GNUNET_NAMESTORE_RF_RELATIVE_EXPIRATION;
 573         rd[i].expiration_time = 0;
 574       }
 575       else
 576       {
 577         rd[i].flags = GNUNET_NAMESTORE_RF_NONE;
 578         rd[i].expiration_time = pos->expiration_time;
 579       }
 580       i++;
 581     }
 582     GNUNET_assert (i == n);
 583     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 584                 "Transmitting standard DNS result with %u records\n",
 585                 n);
 586     rh->proc (rh->proc_cls,
 587               n,
 588               rd);
 589   }
 590   GNS_resolver_lookup_cancel (rh);
 591 }
 592
 593
 594 /**
 595  * Add a result from DNS to the records to be returned to the application.
 596  *
 597  * @param rh resolution request to extend with a result
 598  * @param expiration_time expiration time for the answer
 599  * @param record_type DNS record type of the answer
 600  * @param data_size number of bytes in @a data
 601  * @param data binary data to return in DNS record
 602  */
 603 static void
 604 add_dns_result (struct GNS_ResolverHandle *rh,
 605                 uint64_t expiration_time,
 606                 uint32_t record_type,
 607                 size_t data_size,
 608                 const void *data)
 609 {
 610   struct DnsResult *res;
 611
 612   res = GNUNET_malloc (sizeof (struct DnsResult) + data_size);
 613   res->expiration_time = expiration_time;
 614   res->data_size = data_size;
 615   res->record_type = record_type;
 616   res->data = &res[1];
 617   memcpy (&res[1], data, data_size);
 618   GNUNET_CONTAINER_DLL_insert (rh->dns_result_head,
 619                                rh->dns_result_tail,
 620                                res);
 621 }
 622
 623
 624 /**
 625  * We had to do a DNS lookup.  Convert the result (if any) and return
 626  * it.
 627  *
 628  * @param cls closure with the 'struct GNS_ResolverHandle'
 629  * @param addr one of the addresses of the host, NULL for the last address
 630  * @param addrlen length of the address
 631  */
 632 static void
 633 handle_dns_result (void *cls,
 634                    const struct sockaddr *addr,
 635                    socklen_t addrlen)
 636 {
 637   struct GNS_ResolverHandle *rh = cls;
 638   const struct sockaddr_in *sa4;
 639   const struct sockaddr_in6 *sa6;
 640
 641   rh->std_resolve = NULL;
 642   if (NULL == addr)
 643   {
 644     transmit_lookup_dns_result (rh);
 645     return;
 646   }
 647   switch (addr->sa_family)
 648   {
 649   case AF_INET:
 650     sa4 = (const struct sockaddr_in *) addr;
 651     add_dns_result (rh,
 652                     0 /* expiration time is unknown */,
 653                     GNUNET_DNSPARSER_TYPE_A,
 654                     sizeof (struct in_addr),
 655                     &sa4->sin_addr);
 656     break;
 657   case AF_INET6:
 658     sa6 = (const struct sockaddr_in6 *) addr;
 659     add_dns_result (rh,
 660                     0 /* expiration time is unknown */,
 661                     GNUNET_DNSPARSER_TYPE_AAAA,
 662                     sizeof (struct in6_addr),
 663                     &sa6->sin6_addr);
 664     break;
 665   default:
 666     GNUNET_break (0);
 667     break;
 668   }
 669 }
 670
 671
 672 /**
 673  * Task scheduled to continue with the resolution process.
 674  *
 675  * @param cls the 'struct GNS_ResolverHandle' of the resolution
 676  * @param tc task context
 677  */
 678 static void
 679 recursive_resolution (void *cls,
 680                       const struct GNUNET_SCHEDULER_TaskContext *tc);
 681
 682
 683 /**
 684  * Begin the resolution process from 'name', starting with
 685  * the identification of the zone specified by 'name'.
 686  *
 687  * @param rh resolution to perform
 688  */
 689 static void
 690 start_resolver_lookup (struct GNS_ResolverHandle *rh);
 691
 692
 693 /**
 694  * Function called with the result of a DNS resolution.
 695  *
 696  * @param cls the request handle of the resolution that
 697  *        we were attempting to make
 698  * @param rs socket that received the response
 699  * @param dns dns response, never NULL
 700  * @param dns_len number of bytes in @a dns
 701  */
 702 static void
 703 dns_result_parser (void *cls,
 704                    struct GNUNET_DNSSTUB_RequestSocket *rs,
 705                    const struct GNUNET_TUN_DnsHeader *dns,
 706                    size_t dns_len)
 707 {
 708   struct GNS_ResolverHandle *rh = cls;
 709   struct GNUNET_DNSPARSER_Packet *p;
 710   const struct GNUNET_DNSPARSER_Record *rec;
 711   unsigned int rd_count;
 712   unsigned int i;
 713
 714   rh->dns_request = NULL;
 715   GNUNET_SCHEDULER_cancel (rh->task_id);
 716   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
 717   p = GNUNET_DNSPARSER_parse ((const char *) dns,
 718                               dns_len);
 719   if (NULL == p)
 720   {
 721     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
 722                 _("Failed to parse DNS response\n"));
 723     rh->proc (rh->proc_cls, 0, NULL);
 724     GNS_resolver_lookup_cancel (rh);
 725     return;
 726   }
 727
 728   if ( (p->num_answers > 0) &&
 729        (GNUNET_DNSPARSER_TYPE_CNAME == p->answers[0].type) &&
 730        (GNUNET_DNSPARSER_TYPE_CNAME != rh->record_type) )
 731     {
 732       GNUNET_free (rh->name);
 733       rh->name = GNUNET_strdup (p->answers[0].data.hostname);
 734       start_resolver_lookup (rh);
 735       GNUNET_DNSPARSER_free_packet (p);
 736       return;
 737     }
 738   /* FIXME: add DNAME support */
 739
 740   /* convert from (parsed) DNS to (binary) GNS format! */
 741   rd_count = p->num_answers + p->num_authority_records + p->num_additional_records;
 742   {
 743     struct GNUNET_NAMESTORE_RecordData rd[rd_count];
 744     unsigned int skip;
 745     char buf[UINT16_MAX];
 746     size_t buf_off;
 747
 748     buf_off = 0;
 749     skip = 0;
 750     memset (rd, 0, sizeof (rd));
 751     for (i=0;i<rd_count;i++)
 752     {
 753       if (i < p->num_answers)
 754         rec = &p->answers[i];
 755       else if (i < p->num_answers + p->num_authority_records)
 756         rec = &p->authority_records[i - p->num_answers];
 757       else
 758         rec = &p->authority_records[i - p->num_answers - p->num_authority_records];
 759       /* As we copied the full DNS name to 'rh->ac_tail->label', this
 760          should be the correct check to see if this record is actually
 761          a record for our label... */
 762       if (0 != strcmp (rec->name,
 763                        rh->ac_tail->label))
 764       {
 765         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 766                     "Dropping record `%s', does not match desired name `%s'\n",
 767                     rec->name,
 768                     rh->ac_tail->label);
 769         skip++;
 770         continue;
 771       }
 772       rd[i - skip].record_type = rec->type;
 773       rd[i - skip].expiration_time = rec->expiration_time.abs_value_us;
 774       switch (rec->type)
 775       {
 776       case GNUNET_DNSPARSER_TYPE_A:
 777         if (rec->data.raw.data_len != sizeof (struct in_addr))
 778         {
 779           GNUNET_break_op (0);
 780           skip++;
 781           continue;
 782         }
 783         rd[i - skip].data_size = rec->data.raw.data_len;
 784         rd[i - skip].data = rec->data.raw.data;
 785         break;
 786       case GNUNET_DNSPARSER_TYPE_AAAA:
 787         if (rec->data.raw.data_len != sizeof (struct in6_addr))
 788         {
 789           GNUNET_break_op (0);
 790           skip++;
 791           continue;
 792         }
 793         rd[i - skip].data_size = rec->data.raw.data_len;
 794         rd[i - skip].data = rec->data.raw.data;
 795         break;
 796       case GNUNET_DNSPARSER_TYPE_CNAME:
 797       case GNUNET_DNSPARSER_TYPE_PTR:
 798       case GNUNET_DNSPARSER_TYPE_NS:
 799         if (GNUNET_OK !=
 800             GNUNET_DNSPARSER_builder_add_name (buf,
 801                                                sizeof (buf),
 802                                                &buf_off,
 803                                                rec->data.hostname))
 804         {
 805           GNUNET_break (0);
 806           skip++;
 807           continue;
 808         }
 809         break;
 810       case GNUNET_DNSPARSER_TYPE_SOA:
 811         if (GNUNET_OK !=
 812             GNUNET_DNSPARSER_builder_add_soa (buf,
 813                                                sizeof (buf),
 814                                                &buf_off,
 815                                                rec->data.soa))
 816         {
 817           GNUNET_break (0);
 818           skip++;
 819           continue;
 820         }
 821         break;
 822       case GNUNET_DNSPARSER_TYPE_MX:
 823         if (GNUNET_OK !=
 824             GNUNET_DNSPARSER_builder_add_mx (buf,
 825                                              sizeof (buf),
 826                                              &buf_off,
 827                                              rec->data.mx))
 828         {
 829           GNUNET_break (0);
 830           skip++;
 831           continue;
 832         }
 833         break;
 834       case GNUNET_DNSPARSER_TYPE_SRV:
 835         if (GNUNET_OK !=
 836             GNUNET_DNSPARSER_builder_add_srv (buf,
 837                                               sizeof (buf),
 838                                               &buf_off,
 839                                               rec->data.srv))
 840         {
 841           GNUNET_break (0);
 842           skip++;
 843           continue;
 844         }
 845         break;
 846       default:
 847         GNUNET_log (GNUNET_ERROR_TYPE_INFO,
 848                     _("Skipping record of unsupported type %d\n"),
 849                     rec->type);
 850         skip++;
 851         continue;
 852       }
 853     }
 854     rh->proc (rh->proc_cls, rd_count - skip, rd);
 855     GNS_resolver_lookup_cancel (rh);
 856   }
 857   GNUNET_DNSPARSER_free_packet (p);
 858 }
 859
 860
 861 /**
 862  * Perform recursive DNS resolution.  Asks the given DNS resolver to
 863  * resolve "rh->dns_name", possibly recursively proceeding following
 864  * NS delegations, CNAMES, etc., until 'rh->loop_limiter' bounds us or
 865  * we find the answer.
 866  *
 867  * @param rh resolution information
 868  */
 869 static void
 870 recursive_dns_resolution (struct GNS_ResolverHandle *rh)
 871 {
 872   struct AuthorityChain *ac;
 873   socklen_t sa_len;
 874   struct GNUNET_DNSPARSER_Query *query;
 875   struct GNUNET_DNSPARSER_Packet *p;
 876   char *dns_request;
 877   size_t dns_request_length;
 878
 879   ac = rh->ac_tail;
 880   GNUNET_assert (NULL != ac);
 881   GNUNET_assert (GNUNET_NO == ac->gns_authority);
 882   switch (((const struct sockaddr *) &ac->authority_info.dns_authority.dns_ip)->sa_family)
 883   {
 884   case AF_INET:
 885     sa_len = sizeof (struct sockaddr_in);
 886     break;
 887   case AF_INET6:
 888     sa_len = sizeof (struct sockaddr_in6);
 889     break;
 890   default:
 891     GNUNET_break (0);
 892     rh->proc (rh->proc_cls, 0, NULL);
 893     GNS_resolver_lookup_cancel (rh);
 894     return;
 895   }
 896   query = GNUNET_new (struct GNUNET_DNSPARSER_Query);
 897   query->name = GNUNET_strdup (ac->label);
 898   query->type = rh->record_type;
 899   query->class = GNUNET_TUN_DNS_CLASS_INTERNET;
 900   p = GNUNET_new (struct GNUNET_DNSPARSER_Packet);
 901   p->queries = query;
 902   p->num_queries = 1;
 903   p->id = (uint16_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
 904                                                UINT16_MAX);
 905   p->flags.opcode = GNUNET_TUN_DNS_OPCODE_QUERY;
 906   p->flags.recursion_desired = 1;
 907   if (GNUNET_OK !=
 908       GNUNET_DNSPARSER_pack (p, 1024, &dns_request, &dns_request_length))
 909   {
 910     GNUNET_break (0);
 911     rh->proc (rh->proc_cls, 0, NULL);
 912     GNS_resolver_lookup_cancel (rh);
 913   }
 914   else
 915   {
 916     rh->dns_request = GNUNET_DNSSTUB_resolve (dns_handle,
 917                                               (const struct sockaddr *) &ac->authority_info.dns_authority.dns_ip,
 918                                               sa_len,
 919                                               dns_request,
 920                                               dns_request_length,
 921                                               &dns_result_parser,
 922                                               rh);
 923     rh->task_id = GNUNET_SCHEDULER_add_delayed (DNS_LOOKUP_TIMEOUT,
 924                                                 &fail_resolution,
 925                                                 rh);
 926   }
 927   GNUNET_free (dns_request);
 928   GNUNET_DNSPARSER_free_packet (p);
 929 }
 930
 931
 932 /**
 933  * We encountered a CNAME record during our resolution.
 934  * Merge it into our chain.
 935  *
 936  * @param rh resolution we are performing
 937  * @param cname value of the cname record we got for the current
 938  *        authority chain tail
 939  */
 940 static void
 941 handle_gns_cname_result (struct GNS_ResolverHandle *rh,
 942                          const char *cname)
 943 {
 944   size_t nlen;
 945   char *res;
 946
 947   nlen = strlen (cname);
 948   if ( (nlen > 2) &&
 949        (0 == strcmp (".+",
 950                      &cname[nlen - 2])) )
 951   {
 952     /* CNAME resolution continues relative to current domain */
 953     if (0 == rh->name_resolution_pos)
 954     {
 955       res = GNUNET_strndup (cname, nlen - 2);
 956       rh->name_resolution_pos = nlen - 2;
 957     }
 958     else
 959     {
 960       GNUNET_asprintf (&res,
 961                        "%.*s.%.*s",
 962                        (int) rh->name_resolution_pos,
 963                        rh->name,
 964                        (int) (nlen - 2),
 965                        cname);
 966       rh->name_resolution_pos = strlen (res);
 967     }
 968     GNUNET_free (rh->name);
 969     rh->name = res;
 970     rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
 971                                             rh);
 972     return;
 973   }
 974   /* name is absolute, start from the beginning */
 975   GNUNET_free (rh->name);
 976   rh->name = GNUNET_strdup (cname);
 977   start_resolver_lookup (rh);
 978 }
 979
 980
 981 /**
 982  * Process a records that were decrypted from a block.
 983  *
 984  * @param cls closure with the 'struct GNS_ResolverHandle'
 985  * @param rd_count number of entries in @a rd array
 986  * @param rd array of records with data to store
 987  */
 988 static void
 989 handle_gns_resolution_result (void *cls,
 990                               unsigned int rd_count,
 991                               const struct GNUNET_NAMESTORE_RecordData *rd);
 992
 993
 994 /**
 995  * Callback invoked from the VPN service once a redirection is
 996  * available.  Provides the IP address that can now be used to
 997  * reach the requested destination.  Replaces the "VPN" record
 998  * with the respective A/AAAA record and continues processing.
 999  *
1000  * @param cls closure
1001  * @param af address family, AF_INET or AF_INET6; AF_UNSPEC on error;
1002  *                will match 'result_af' from the request
1003  * @param address IP address (struct in_addr or struct in_addr6, depending on 'af')
1004  *                that the VPN allocated for the redirection;
1005  *                traffic to this IP will now be redirected to the
1006  *                specified target peer; NULL on error
1007  */
1008 static void
1009 vpn_allocation_cb (void *cls,
1010                    int af,
1011                    const void *address)
1012 {
1013   struct VpnContext *vpn_ctx = cls;
1014   struct GNS_ResolverHandle *rh = vpn_ctx->rh;
1015   struct GNUNET_NAMESTORE_RecordData rd[vpn_ctx->rd_count];
1016   unsigned int i;
1017
1018   vpn_ctx->vpn_request = NULL;
1019   rh->vpn_ctx = NULL;
1020   GNUNET_assert (GNUNET_OK ==
1021                  GNUNET_NAMESTORE_records_deserialize (vpn_ctx->rd_data_size,
1022                                                        vpn_ctx->rd_data,
1023                                                        vpn_ctx->rd_count,
1024                                                        rd));
1025   for (i=0;i<vpn_ctx->rd_count;i++)
1026   {
1027     if (GNUNET_NAMESTORE_TYPE_VPN == rd[i].record_type)
1028     {
1029       switch (af)
1030       {
1031       case AF_INET:
1032         rd[i].record_type = GNUNET_DNSPARSER_TYPE_A;
1033         rd[i].data_size = sizeof (struct in_addr);
1034         rd[i].expiration_time = GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT).abs_value_us;
1035         rd[i].flags = 0;
1036         rd[i].data = address;
1037         break;
1038       case AF_INET6:
1039         rd[i].record_type = GNUNET_DNSPARSER_TYPE_AAAA;
1040         rd[i].expiration_time = GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT).abs_value_us;
1041         rd[i].flags = 0;
1042         rd[i].data = address;
1043         rd[i].data_size = sizeof (struct in6_addr);
1044         break;
1045       default:
1046         GNUNET_assert (0);
1047       }
1048       break;
1049     }
1050   }
1051   GNUNET_assert (i < vpn_ctx->rd_count);
1052   handle_gns_resolution_result (rh,
1053                                 vpn_ctx->rd_count,
1054                                 rd);
1055   GNUNET_free (vpn_ctx->rd_data);
1056   GNUNET_free (vpn_ctx);
1057 }
1058
1059
1060 /**
1061  * Process a records that were decrypted from a block.
1062  *
1063  * @param cls closure with the 'struct GNS_ResolverHandle'
1064  * @param rd_count number of entries in @a rd array
1065  * @param rd array of records with data to store
1066  */
1067 static void
1068 handle_gns_resolution_result (void *cls,
1069                               unsigned int rd_count,
1070                               const struct GNUNET_NAMESTORE_RecordData *rd)
1071 {
1072   struct GNS_ResolverHandle *rh = cls;
1073   struct AuthorityChain *ac;
1074   unsigned int i;
1075   unsigned int j;
1076   struct sockaddr *sa;
1077   struct sockaddr_in v4;
1078   struct sockaddr_in6 v6;
1079   size_t sa_len;
1080   char *cname;
1081   struct VpnContext *vpn_ctx;
1082   const struct GNUNET_TUN_GnsVpnRecord *vpn;
1083   const char *vname;
1084   struct GNUNET_HashCode vhash;
1085   int af;
1086   char scratch[UINT16_MAX];
1087   size_t scratch_off;
1088   size_t scratch_start;
1089   size_t off;
1090   struct GNUNET_NAMESTORE_RecordData rd_new[rd_count];
1091   unsigned int rd_off;
1092
1093   if (0 == rh->name_resolution_pos)
1094   {
1095     /* top-level match, are we done yet? */
1096     if ( (rd_count > 0) &&
1097          (GNUNET_DNSPARSER_TYPE_CNAME == rd[0].record_type) &&
1098          (GNUNET_DNSPARSER_TYPE_CNAME != rh->record_type) )
1099     {
1100       cname = GNUNET_strndup (rd[0].data,
1101                               rd[0].data_size);
1102       handle_gns_cname_result (rh,
1103                                cname);
1104       GNUNET_free (cname);
1105       return;
1106     }
1107     /* If A/AAAA was requested, but we got a VPN
1108        record, we convert it to A/AAAA using GNUnet VPN */
1109     if ( (GNUNET_DNSPARSER_TYPE_A == rh->record_type) ||
1110          (GNUNET_DNSPARSER_TYPE_AAAA == rh->record_type) )
1111     {
1112       for (i=0;i<rd_count;i++)
1113       {
1114         if (GNUNET_NAMESTORE_TYPE_VPN == rd[i].record_type)
1115         {
1116           af = (GNUNET_DNSPARSER_TYPE_A == rh->record_type) ? AF_INET : AF_INET6;
1117           if (sizeof (struct GNUNET_TUN_GnsVpnRecord) <
1118               rd[i].data_size)
1119           {
1120             GNUNET_break_op (0);
1121             rh->proc (rh->proc_cls, 0, NULL);
1122             GNS_resolver_lookup_cancel (rh);
1123             return;
1124           }
1125           vpn = (const struct GNUNET_TUN_GnsVpnRecord *) rd[i].data;
1126           vname = (const char *) &vpn[1];
1127           if ('\0' != vname[rd[i].data_size - 1 - sizeof (struct GNUNET_TUN_GnsVpnRecord)])
1128           {
1129             GNUNET_break_op (0);
1130             rh->proc (rh->proc_cls, 0, NULL);
1131             GNS_resolver_lookup_cancel (rh);
1132             return;
1133           }
1134           GNUNET_CRYPTO_hash (vname,
1135                               strlen (vname), // FIXME: +1?
1136                               &vhash);
1137           vpn_ctx = GNUNET_new (struct VpnContext);
1138           rh->vpn_ctx = vpn_ctx;
1139           vpn_ctx->rh = rh;
1140           vpn_ctx->rd_data_size = GNUNET_NAMESTORE_records_get_size (rd_count,
1141                                                                      rd);
1142           vpn_ctx->rd_data = GNUNET_malloc (vpn_ctx->rd_data_size);
1143           (void) GNUNET_NAMESTORE_records_serialize (rd_count,
1144                                                      rd,
1145                                                      vpn_ctx->rd_data_size,
1146                                                      vpn_ctx->rd_data);
1147           vpn_ctx->vpn_request = GNUNET_VPN_redirect_to_peer (vpn_handle,
1148                                                               af,
1149                                                               ntohs (vpn->proto),
1150                                                               &vpn->peer,
1151                                                               &vhash,
1152                                                               GNUNET_NO,
1153                                                               GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT),
1154                                                               &vpn_allocation_cb,
1155                                                               rh);
1156           return;
1157         }
1158       }
1159     }
1160     /* convert relative names in record values to absolute names,
1161        using 'scratch' array for memory allocations */
1162     scratch_off = 0;
1163     rd_off = 0;
1164     for (i=0;i<rd_count;i++)
1165     {
1166       rd_new[rd_off] = rd[i];
1167       /* Check if the embedded name(s) end in "+", and if so,
1168          replace the "+" with the zone at "ac_tail", changing the name
1169          to a ".zkey".  The name is allocated on the 'scratch' array,
1170          so we can free it afterwards. */
1171       switch (rd[i].record_type)
1172       {
1173       case GNUNET_DNSPARSER_TYPE_CNAME:
1174         {
1175           char *cname;
1176
1177           off = 0;
1178           cname = GNUNET_DNSPARSER_parse_name (rd[i].data,
1179                                                rd[i].data_size,
1180                                                &off);
1181           if ( (NULL == cname) ||
1182                (off != rd[i].data_size) )
1183           {
1184             GNUNET_break_op (0); /* record not well-formed */
1185           }
1186           else
1187           {
1188             cname = translate_dot_plus (rh, cname);
1189             scratch_start = scratch_off;
1190             if (GNUNET_OK !=
1191                 GNUNET_DNSPARSER_builder_add_name (scratch,
1192                                                    sizeof (scratch),
1193                                                    &scratch_off,
1194                                                    cname))
1195             {
1196               GNUNET_break (0);
1197             }
1198             else
1199             {
1200               rd_new[rd_off].data = &scratch[scratch_start];
1201               rd_new[rd_off].data_size = scratch_off - scratch_start;
1202               rd_off++;
1203             }
1204           }
1205           GNUNET_free_non_null (cname);
1206         }
1207         break;
1208       case GNUNET_DNSPARSER_TYPE_SOA:
1209         {
1210           struct GNUNET_DNSPARSER_SoaRecord *soa;
1211
1212           off = 0;
1213           soa = GNUNET_DNSPARSER_parse_soa (rd[i].data,
1214                                             rd[i].data_size,
1215                                             &off);
1216           if ( (NULL == soa) ||
1217                (off != rd[i].data_size) )
1218           {
1219             GNUNET_break_op (0); /* record not well-formed */
1220           }
1221           else
1222           {
1223             soa->mname = translate_dot_plus (rh, soa->mname);
1224             soa->rname = translate_dot_plus (rh, soa->rname);
1225             scratch_start = scratch_off;
1226             if (GNUNET_OK !=
1227                 GNUNET_DNSPARSER_builder_add_soa (scratch,
1228                                                   sizeof (scratch),
1229                                                   &scratch_off,
1230                                                   soa))
1231             {
1232               GNUNET_break (0);
1233             }
1234             else
1235             {
1236               rd_new[rd_off].data = &scratch[scratch_start];
1237               rd_new[rd_off].data_size = scratch_off - scratch_start;
1238               rd_off++;
1239             }
1240           }
1241           if (NULL != soa)
1242             GNUNET_DNSPARSER_free_soa (soa);
1243         }
1244         break;
1245       case GNUNET_DNSPARSER_TYPE_MX:
1246         {
1247           struct GNUNET_DNSPARSER_MxRecord *mx;
1248
1249           off = 0;
1250           mx = GNUNET_DNSPARSER_parse_mx (rd[i].data,
1251                                           rd[i].data_size,
1252                                           &off);
1253           if ( (NULL == mx) ||
1254                (off != rd[i].data_size) )
1255           {
1256             GNUNET_break_op (0); /* record not well-formed */
1257           }
1258           else
1259           {
1260             mx->mxhost = translate_dot_plus (rh, mx->mxhost);
1261             scratch_start = scratch_off;
1262             if (GNUNET_OK !=
1263                 GNUNET_DNSPARSER_builder_add_mx (scratch,
1264                                                  sizeof (scratch),
1265                                                  &scratch_off,
1266                                                  mx))
1267             {
1268               GNUNET_break (0);
1269             }
1270             else
1271             {
1272               rd_new[rd_off].data = &scratch[scratch_start];
1273               rd_new[rd_off].data_size = scratch_off - scratch_start;
1274               rd_off++;
1275             }
1276           }
1277           if (NULL != mx)
1278             GNUNET_DNSPARSER_free_mx (mx);
1279         }
1280         break;
1281       case GNUNET_DNSPARSER_TYPE_SRV:
1282         {
1283           struct GNUNET_DNSPARSER_SrvRecord *srv;
1284
1285           off = 0;
1286           /* FIXME: passing rh->name here is is not necessarily what we want
1287              (SRV support not finished) */
1288           srv = GNUNET_DNSPARSER_parse_srv (rh->name,
1289                                             rd[i].data,
1290                                             rd[i].data_size,
1291                                             &off);
1292           if ( (NULL == srv) ||
1293                (off != rd[i].data_size) )
1294           {
1295             GNUNET_break_op (0); /* record not well-formed */
1296           }
1297           else
1298           {
1299             srv->domain_name = translate_dot_plus (rh, srv->domain_name);
1300             srv->target = translate_dot_plus (rh, srv->target);
1301             scratch_start = scratch_off;
1302             if (GNUNET_OK !=
1303                 GNUNET_DNSPARSER_builder_add_srv (scratch,
1304                                                   sizeof (scratch),
1305                                                   &scratch_off,
1306                                                   srv))
1307             {
1308               GNUNET_break (0);
1309             }
1310             else
1311             {
1312               rd_new[rd_off].data = &scratch[scratch_start];
1313               rd_new[rd_off].data_size = scratch_off - scratch_start;
1314               rd_off++;
1315             }
1316           }
1317           if (NULL != srv)
1318             GNUNET_DNSPARSER_free_srv (srv);
1319         }
1320         break;
1321       case GNUNET_NAMESTORE_TYPE_PKEY:
1322         /* tigger shortening */
1323         if (NULL != rh->shorten_key)
1324         {
1325           struct GNUNET_CRYPTO_EccPublicSignKey pub;
1326
1327           if (rd[i].data_size != sizeof (struct GNUNET_CRYPTO_EccPublicSignKey))
1328           {
1329             GNUNET_break_op (0);
1330             break;
1331           }
1332           memcpy (&pub, rd[i].data, rd[i].data_size);
1333           GNS_shorten_start (rh->ac_tail->label,
1334                              &pub,
1335                              rh->shorten_key);
1336         }
1337       default:
1338         break;
1339       }
1340     }
1341
1342     /* yes, we are done, return result */
1343     rh->proc (rh->proc_cls, rd_off, rd_new);
1344     GNS_resolver_lookup_cancel (rh);
1345     return;
1346   }
1347   /* need to recurse, check if we can */
1348   for (i=0;i<rd_count;i++)
1349   {
1350     switch (rd[i].record_type)
1351     {
1352     case GNUNET_NAMESTORE_TYPE_PKEY:
1353       /* delegation to another zone */
1354       if (sizeof (struct GNUNET_CRYPTO_EccPublicSignKey) !=
1355           rd[i].data_size)
1356       {
1357         GNUNET_break_op (0);
1358         rh->proc (rh->proc_cls, 0, NULL);
1359         GNS_resolver_lookup_cancel (rh);
1360         return;
1361       }
1362       /* expand authority chain */
1363       ac = GNUNET_new (struct AuthorityChain);
1364       ac->rh = rh;
1365       ac->gns_authority = GNUNET_YES;
1366       memcpy (&ac->authority_info.gns_authority,
1367               rd[i].data,
1368               sizeof (struct GNUNET_CRYPTO_EccPublicSignKey));
1369       ac->label = resolver_lookup_get_next_label (rh);
1370       /* tigger shortening */
1371       if (NULL != rh->shorten_key)
1372         GNS_shorten_start (rh->ac_tail->label,
1373                            &ac->authority_info.gns_authority,
1374                            rh->shorten_key);
1375       /* add AC to tail */
1376       GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1377                                         rh->ac_tail,
1378                                         ac);
1379       /* recurse */
1380       rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1381                                               rh);
1382       break;
1383     case GNUNET_DNSPARSER_TYPE_NS:
1384       /* resolution continues within DNS */
1385       if (GNUNET_DNSPARSER_MAX_NAME_LENGTH < rd[i].data_size)
1386       {
1387         GNUNET_break_op (0);
1388         rh->proc (rh->proc_cls, 0, NULL);
1389         GNS_resolver_lookup_cancel (rh);
1390         return;
1391       }
1392       /* find associated A/AAAA record */
1393       sa = NULL;
1394       sa_len = 0;
1395       for (j=0;j<rd_count;j++)
1396       {
1397         switch (rd[j].record_type)
1398         {
1399         case GNUNET_DNSPARSER_TYPE_A:
1400           if (sizeof (struct in_addr) != rd[i].data_size)
1401           {
1402             GNUNET_break_op (0);
1403             rh->proc (rh->proc_cls, 0, NULL);
1404             GNS_resolver_lookup_cancel (rh);
1405             return;
1406           }
1407           /* FIXME: might want to check if we support IPv4 here,
1408              and otherwise skip this one and hope we find another */
1409           memset (&v4, 0, sizeof (v4));
1410           sa_len = sizeof (v4);
1411           v4.sin_family = AF_INET;
1412           v4.sin_port = htons (53);
1413 #if HAVE_SOCKADDR_IN_SIN_LEN
1414           v4.sin_len = (u_char) sa_len;
1415 #endif
1416           memcpy (&v4.sin_addr,
1417                   rd[j].data,
1418                   sizeof (struct in_addr));
1419           sa = (struct sockaddr *) &v4;
1420           break;
1421         case GNUNET_DNSPARSER_TYPE_AAAA:
1422           if (sizeof (struct in6_addr) != rd[i].data_size)
1423           {
1424             GNUNET_break_op (0);
1425             rh->proc (rh->proc_cls, 0, NULL);
1426             GNS_resolver_lookup_cancel (rh);
1427             return;
1428           }
1429           /* FIXME: might want to check if we support IPv6 here,
1430              and otherwise skip this one and hope we find another */
1431           memset (&v6, 0, sizeof (v6));
1432           sa_len = sizeof (v6);
1433           v6.sin6_family = AF_INET6;
1434           v6.sin6_port = htons (53);
1435 #if HAVE_SOCKADDR_IN_SIN_LEN
1436           v6.sin6_len = (u_char) sa_len;
1437 #endif
1438           memcpy (&v6.sin6_addr,
1439                   rd[j].data,
1440                   sizeof (struct in6_addr));
1441           sa = (struct sockaddr *) &v6;
1442           break;
1443         default:
1444           break;
1445         }
1446         if (NULL != sa)
1447           break;
1448       }
1449       if (NULL == sa)
1450       {
1451         /* we cannot continue; NS without A/AAAA */
1452         rh->proc (rh->proc_cls, 0, NULL);
1453         GNS_resolver_lookup_cancel (rh);
1454         return;
1455       }
1456       /* expand authority chain */
1457       ac = GNUNET_new (struct AuthorityChain);
1458       ac->rh = rh;
1459       strncpy (ac->authority_info.dns_authority.name,
1460                rd[i].data,
1461                rd[i].data_size);
1462       ac->authority_info.dns_authority.name[rd[i].data_size] = '\0';
1463       memcpy (&ac->authority_info.dns_authority.dns_ip,
1464               sa,
1465               sa_len);
1466       /* for DNS recursion, the label is the full DNS name,
1467          created from the remainder of the GNS name and the
1468          name in the NS record */
1469       GNUNET_asprintf (&ac->label,
1470                        "%.*s%s",
1471                        (int) rh->name_resolution_pos,
1472                        rh->name,
1473                        ac->authority_info.dns_authority.name);
1474       GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1475                                         rh->ac_tail,
1476                                         ac);
1477       if (strlen (ac->label) > GNUNET_DNSPARSER_MAX_NAME_LENGTH)
1478       {
1479         GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1480                     _("GNS lookup resulted in DNS name that is too long (`%s')\n"),
1481                     ac->label);
1482         rh->proc (rh->proc_cls, 0, NULL);
1483         GNS_resolver_lookup_cancel (rh);
1484         return;
1485       }
1486       /* recurse */
1487       rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1488                                               rh);
1489       return;
1490     case GNUNET_DNSPARSER_TYPE_CNAME:
1491       cname = GNUNET_strndup (rd[i].data,
1492                               rd[i].data_size);
1493       handle_gns_cname_result (rh,
1494                                cname);
1495       GNUNET_free (cname);
1496       return;
1497       /* FIXME: handle DNAME */
1498     default:
1499       /* skip */
1500       break;
1501     }
1502   }
1503   GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1504               _("GNS lookup recursion failed (no delegation record found)\n"));
1505   rh->proc (rh->proc_cls, 0, NULL);
1506   GNS_resolver_lookup_cancel (rh);
1507 }
1508
1509
1510 /**
1511  * Function called once the namestore has completed the request for
1512  * caching a block.
1513  *
1514  * @param cls closure with the 'struct GNS_ResolverHandle'
1515  * @param success #GNUNET_OK on success
1516  * @param emsg error message
1517  */
1518 static void
1519 namestore_cache_continuation (void *cls,
1520                               int32_t success,
1521                               const char *emsg)
1522 {
1523   struct GNS_ResolverHandle *rh = cls;
1524
1525   rh->namestore_qe = NULL;
1526   if (NULL != emsg)
1527     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1528                 _("Failed to cache GNS resolution: %s\n"),
1529                 emsg);
1530 }
1531
1532
1533 /**
1534  * Iterator called on each result obtained for a DHT
1535  * operation that expects a reply
1536  *
1537  * @param cls closure with the 'struct GNS_ResolverHandle'
1538  * @param exp when will this value expire
1539  * @param key key of the result
1540  * @param get_path peers on reply path (or NULL if not recorded)
1541  *                 [0] = datastore's first neighbor, [length - 1] = local peer
1542  * @param get_path_length number of entries in get_path
1543  * @param put_path peers on the PUT path (or NULL if not recorded)
1544  *                 [0] = origin, [length - 1] = datastore
1545  * @param put_path_length number of entries in get_path
1546  * @param type type of the result
1547  * @param size number of bytes in data
1548  * @param data pointer to the result data
1549  */
1550 static void
1551 handle_dht_response (void *cls,
1552                      struct GNUNET_TIME_Absolute exp,
1553                      const struct GNUNET_HashCode * key,
1554                      const struct GNUNET_PeerIdentity *get_path,
1555                      unsigned int get_path_length,
1556                      const struct GNUNET_PeerIdentity *put_path,
1557                      unsigned int put_path_length,
1558                      enum GNUNET_BLOCK_Type type,
1559                      size_t size, const void *data)
1560 {
1561   struct GNS_ResolverHandle *rh = cls;
1562   struct AuthorityChain *ac = rh->ac_tail;
1563   const struct GNUNET_NAMESTORE_Block *block;
1564
1565   GNUNET_DHT_get_stop (rh->get_handle);
1566   rh->get_handle = NULL;
1567   GNUNET_CONTAINER_heap_remove_node (rh->dht_heap_node);
1568   rh->dht_heap_node = NULL;
1569   if (size < sizeof (struct GNUNET_NAMESTORE_Block))
1570   {
1571     /* how did this pass DHT block validation!? */
1572     GNUNET_break (0);
1573     rh->proc (rh->proc_cls, 0, NULL);
1574     GNS_resolver_lookup_cancel (rh);
1575     return;
1576   }
1577   block = data;
1578   if (size !=
1579       ntohs (block->purpose.size) +
1580       sizeof (struct GNUNET_CRYPTO_EccPublicSignKey) +
1581       sizeof (struct GNUNET_CRYPTO_EccSignature))
1582   {
1583     /* how did this pass DHT block validation!? */
1584     GNUNET_break (0);
1585     rh->proc (rh->proc_cls, 0, NULL);
1586     GNS_resolver_lookup_cancel (rh);
1587     return;
1588   }
1589   if (GNUNET_OK !=
1590       GNUNET_NAMESTORE_block_decrypt (block,
1591                                       &ac->authority_info.gns_authority,
1592                                       ac->label,
1593                                       &handle_gns_resolution_result,
1594                                       rh))
1595   {
1596     GNUNET_break_op (0); /* block was ill-formed */
1597     rh->proc (rh->proc_cls, 0, NULL);
1598     GNS_resolver_lookup_cancel (rh);
1599     return;
1600   }
1601   /* Cache well-formed blocks */
1602   rh->namestore_qe = GNUNET_NAMESTORE_block_cache (namestore_handle,
1603                                                    block,
1604                                                    &namestore_cache_continuation,
1605                                                    rh);
1606 }
1607
1608
1609 /**
1610  * Process a record that was stored in the namestore.
1611  *
1612  * @param cls closure with the `struct GNS_ResolverHandle`
1613  * @param block block that was stored in the namestore
1614  */
1615 static void
1616 handle_namestore_block_response (void *cls,
1617                                  const struct GNUNET_NAMESTORE_Block *block)
1618 {
1619   struct GNS_ResolverHandle *rh = cls;
1620   struct GNS_ResolverHandle *rx;
1621   struct AuthorityChain *ac = rh->ac_tail;
1622   const char *label = ac->label;
1623   const struct GNUNET_CRYPTO_EccPublicSignKey *auth = &ac->authority_info.gns_authority;
1624   struct GNUNET_HashCode query;
1625
1626   GNUNET_NAMESTORE_query_from_public_key (auth,
1627                                           label,
1628                                           &query);
1629   rh->namestore_qe = NULL;
1630   if ( (GNUNET_NO == rh->only_cached) &&
1631        ( (NULL == block) ||
1632          (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us) ) )
1633   {
1634     /* Namestore knows nothing; try DHT lookup */
1635     rh->get_handle = GNUNET_DHT_get_start (dht_handle,
1636                                            GNUNET_BLOCK_TYPE_GNS_NAMERECORD,
1637                                            &query,
1638                                            DHT_GNS_REPLICATION_LEVEL,
1639                                            GNUNET_DHT_RO_DEMULTIPLEX_EVERYWHERE,
1640                                            NULL, 0,
1641                                            &handle_dht_response, rh);
1642     rh->dht_heap_node = GNUNET_CONTAINER_heap_insert (dht_lookup_heap,
1643                                                       rh,
1644                                                       GNUNET_TIME_absolute_get ().abs_value_us);
1645     if (GNUNET_CONTAINER_heap_get_size (dht_lookup_heap) > max_allowed_background_queries)
1646     {
1647       /* fail longest-standing DHT request */
1648       rx = GNUNET_CONTAINER_heap_peek (dht_lookup_heap);
1649       GNUNET_assert (NULL != rx);
1650       rx->proc (rx->proc_cls, 0, NULL);
1651       GNS_resolver_lookup_cancel (rx);
1652     }
1653     return;
1654   }
1655   if ( (NULL == block) ||
1656        (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us) )
1657   {
1658     /* DHT not permitted and no local result, fail */
1659     rh->proc (rh->proc_cls, 0, NULL);
1660     GNS_resolver_lookup_cancel (rh);
1661     return;
1662   }
1663   if (GNUNET_OK !=
1664       GNUNET_NAMESTORE_block_decrypt (block,
1665                                       auth,
1666                                       label,
1667                                       &handle_gns_resolution_result,
1668                                       rh))
1669   {
1670     GNUNET_break_op (0); /* block was ill-formed */
1671     rh->proc (rh->proc_cls, 0, NULL);
1672     GNS_resolver_lookup_cancel (rh);
1673     return;
1674   }
1675 }
1676
1677
1678 /**
1679  * Lookup tail of our authority chain in the namestore.
1680  *
1681  * @param rh query we are processing
1682  */
1683 static void
1684 recursive_gns_resolution_namestore (struct GNS_ResolverHandle *rh)
1685 {
1686   struct AuthorityChain *ac = rh->ac_tail;
1687   struct GNUNET_HashCode query;
1688
1689   GNUNET_NAMESTORE_query_from_public_key (&ac->authority_info.gns_authority,
1690                                           ac->label,
1691                                           &query);
1692   rh->namestore_qe = GNUNET_NAMESTORE_lookup_block (namestore_handle,
1693                                                     &query,
1694                                                     &handle_namestore_block_response,
1695                                                     rh);
1696 }
1697
1698
1699 /**
1700  * Task scheduled to continue with the resolution process.
1701  *
1702  * @param cls the `struct GNS_ResolverHandle` of the resolution
1703  * @param tc task context
1704  */
1705 static void
1706 recursive_resolution (void *cls,
1707                       const struct GNUNET_SCHEDULER_TaskContext *tc)
1708 {
1709   struct GNS_ResolverHandle *rh = cls;
1710
1711   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
1712   if (MAX_RECURSION < rh->loop_limiter++)
1713   {
1714     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1715                 "Encountered unbounded recursion resolving `%s'\n",
1716                 rh->name);
1717     rh->proc (rh->proc_cls, 0, NULL);
1718     GNS_resolver_lookup_cancel (rh);
1719     return;
1720   }
1721   if (GNUNET_YES == rh->ac_tail->gns_authority)
1722     recursive_gns_resolution_namestore (rh);
1723   else
1724     recursive_dns_resolution (rh);
1725 }
1726
1727
1728 /**
1729  * Begin the resolution process from 'name', starting with
1730  * the identification of the zone specified by 'name'.
1731  *
1732  * @param rh resolution to perform
1733  */
1734 static void
1735 start_resolver_lookup (struct GNS_ResolverHandle *rh)
1736 {
1737   struct AuthorityChain *ac;
1738   char *x;
1739   char *y;
1740   char *pkey;
1741
1742   if ( ( (GNUNET_YES == is_canonical (rh->name)) &&
1743          (0 != strcmp (GNUNET_GNS_TLD, rh->name)) ) ||
1744        ( (GNUNET_YES != is_gnu_tld (rh->name)) &&
1745          (GNUNET_YES != is_zkey_tld (rh->name)) ) )
1746   {
1747     /* use standard DNS lookup */
1748     int af;
1749
1750     switch (rh->record_type)
1751     {
1752     case GNUNET_DNSPARSER_TYPE_A:
1753       af = AF_INET;
1754       break;
1755     case GNUNET_DNSPARSER_TYPE_AAAA:
1756       af = AF_INET6;
1757       break;
1758     default:
1759       af = AF_UNSPEC;
1760       break;
1761     }
1762     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1763                 "Doing standard DNS lookup for `%s'\n",
1764                 rh->name);
1765     rh->std_resolve = GNUNET_RESOLVER_ip_get (rh->name,
1766                                               af,
1767                                               DNS_LOOKUP_TIMEOUT,
1768                                               &handle_dns_result,
1769                                               rh);
1770     return;
1771   }
1772   if (is_zkey_tld (rh->name))
1773   {
1774     /* Name ends with ".zkey", try to replace authority zone with zkey
1775        authority */
1776     GNUNET_free (resolver_lookup_get_next_label (rh)); /* will return "zkey" */
1777     x = resolver_lookup_get_next_label (rh); /* will return 'x' coordinate */
1778     y = resolver_lookup_get_next_label (rh); /* will return 'y' coordinate */
1779     GNUNET_asprintf (&pkey,
1780                      "%s%s",
1781                      x, y);
1782     if ( (NULL == x) ||
1783          (NULL == y) ||
1784          (GNUNET_OK !=
1785           GNUNET_CRYPTO_ecc_public_sign_key_from_string (pkey,
1786                                                     strlen (pkey),
1787                                                     &rh->authority_zone)) )
1788     {
1789       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1790                   _("Hostname `%s' is not well-formed, resolution fails\n"),
1791                   rh->name);
1792       rh->task_id = GNUNET_SCHEDULER_add_now (&fail_resolution, rh);
1793     }
1794     GNUNET_free_non_null (x);
1795     GNUNET_free_non_null (y);
1796     GNUNET_free (pkey);
1797   }
1798   else
1799   {
1800     /* Name ends with ".gnu", eat ".gnu" and continue with resolution */
1801     GNUNET_free (resolver_lookup_get_next_label (rh));
1802   }
1803   ac = GNUNET_new (struct AuthorityChain);
1804   ac->rh = rh;
1805   ac->label = resolver_lookup_get_next_label (rh);
1806   if (NULL == ac->label)
1807     /* name was just "gnu", so we default to label '+' */
1808     ac->label = GNUNET_strdup (GNUNET_GNS_MASTERZONE_STR);
1809   ac->gns_authority = GNUNET_YES;
1810   ac->authority_info.gns_authority = rh->authority_zone;
1811   GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1812                                     rh->ac_tail,
1813                                     ac);
1814   rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1815                                           rh);
1816 }
1817
1818
1819 /**
1820  * Lookup of a record in a specific zone calls lookup result processor
1821  * on result.
1822  *
1823  * @param zone the zone to perform the lookup in
1824  * @param record_type the record type to look up
1825  * @param name the name to look up
1826  * @param shorten_key a private key for use with PSEU import (can be NULL)
1827  * @param only_cached #GNUNET_NO to only check locally not DHT for performance
1828  * @param proc the processor to call on result
1829  * @param proc_cls the closure to pass to @a proc
1830  * @return handle to cancel operation
1831  */
1832 struct GNS_ResolverHandle *
1833 GNS_resolver_lookup (const struct GNUNET_CRYPTO_EccPublicSignKey *zone,
1834                      uint32_t record_type,
1835                      const char *name,
1836                      const struct GNUNET_CRYPTO_EccPrivateKey *shorten_key,
1837                      int only_cached,
1838                      GNS_ResultProcessor proc, void *proc_cls)
1839 {
1840   struct GNS_ResolverHandle *rh;
1841
1842   rh = GNUNET_new (struct GNS_ResolverHandle);
1843   GNUNET_CONTAINER_DLL_insert (rlh_head,
1844                                rlh_tail,
1845                                rh);
1846   rh->authority_zone = *zone;
1847   rh->proc = proc;
1848   rh->proc_cls = proc_cls;
1849   rh->only_cached = only_cached;
1850   rh->record_type = record_type;
1851   rh->name = GNUNET_strdup (name);
1852   rh->name_resolution_pos = strlen (name);
1853   if (NULL != shorten_key)
1854   {
1855     rh->shorten_key = GNUNET_new (struct GNUNET_CRYPTO_EccPrivateKey);
1856     *rh->shorten_key = *shorten_key;
1857   }
1858   start_resolver_lookup (rh);
1859   return rh;
1860 }
1861
1862
1863 /**
1864  * Cancel active resolution (i.e. client disconnected).
1865  *
1866  * @param rh resolution to abort
1867  */
1868 void
1869 GNS_resolver_lookup_cancel (struct GNS_ResolverHandle *rh)
1870 {
1871   struct DnsResult *dr;
1872   struct AuthorityChain *ac;
1873   struct VpnContext *vpn_ctx;
1874
1875   GNUNET_CONTAINER_DLL_remove (rlh_head,
1876                                rlh_tail,
1877                                rh);
1878   while (NULL != (ac = rh->ac_head))
1879   {
1880     GNUNET_CONTAINER_DLL_remove (rh->ac_head,
1881                                  rh->ac_tail,
1882                                  ac);
1883     GNUNET_free (ac->label);
1884     GNUNET_free (ac);
1885   }
1886   if (GNUNET_SCHEDULER_NO_TASK != rh->task_id)
1887   {
1888     GNUNET_SCHEDULER_cancel (rh->task_id);
1889     rh->task_id = GNUNET_SCHEDULER_NO_TASK;
1890   }
1891   if (NULL != rh->get_handle)
1892   {
1893     GNUNET_DHT_get_stop (rh->get_handle);
1894     rh->get_handle = NULL;
1895   }
1896   if (NULL != rh->dht_heap_node)
1897   {
1898     GNUNET_CONTAINER_heap_remove_node (rh->dht_heap_node);
1899     rh->dht_heap_node = NULL;
1900   }
1901   if (NULL != (vpn_ctx = rh->vpn_ctx))
1902   {
1903     GNUNET_VPN_cancel_request (vpn_ctx->vpn_request);
1904     GNUNET_free (vpn_ctx->rd_data);
1905     GNUNET_free (vpn_ctx);
1906   }
1907   if (NULL != rh->dns_request)
1908   {
1909     GNUNET_DNSSTUB_resolve_cancel (rh->dns_request);
1910     rh->dns_request = NULL;
1911   }
1912   if (NULL != rh->namestore_qe)
1913   {
1914     GNUNET_NAMESTORE_cancel (rh->namestore_qe);
1915     rh->namestore_qe = NULL;
1916   }
1917   if (NULL != rh->std_resolve)
1918   {
1919     GNUNET_RESOLVER_request_cancel (rh->std_resolve);
1920     rh->std_resolve = NULL;
1921   }
1922   while (NULL != (dr = rh->dns_result_head))
1923   {
1924     GNUNET_CONTAINER_DLL_remove (rh->dns_result_head,
1925                                  rh->dns_result_tail,
1926                                  dr);
1927     GNUNET_free (dr);
1928   }
1929   GNUNET_free_non_null (rh->shorten_key);
1930   GNUNET_free (rh->name);
1931   GNUNET_free (rh);
1932 }
1933
1934
1935 /* ***************** Resolver initialization ********************* */
1936
1937
1938 /**
1939  * Initialize the resolver
1940  *
1941  * @param nh the namestore handle
1942  * @param dht the dht handle
1943  * @param c configuration handle
1944  * @param max_bg_queries maximum number of parallel background queries in dht
1945  */
1946 void
1947 GNS_resolver_init (struct GNUNET_NAMESTORE_Handle *nh,
1948                    struct GNUNET_DHT_Handle *dht,
1949                    const struct GNUNET_CONFIGURATION_Handle *c,
1950                    unsigned long long max_bg_queries)
1951 {
1952   char *dns_ip;
1953
1954   cfg = c;
1955   namestore_handle = nh;
1956   dht_handle = dht;
1957   dht_lookup_heap =
1958     GNUNET_CONTAINER_heap_create (GNUNET_CONTAINER_HEAP_ORDER_MIN);
1959   max_allowed_background_queries = max_bg_queries;
1960   if (GNUNET_OK !=
1961       GNUNET_CONFIGURATION_get_value_string (c,
1962                                              "gns",
1963                                              "DNS_RESOLVER",
1964                                              &dns_ip))
1965   {
1966     /* user did not specify DNS resolver, use 8.8.8.8 */
1967     dns_ip = GNUNET_strdup ("8.8.8.8");
1968   }
1969   dns_handle = GNUNET_DNSSTUB_start (dns_ip);
1970   GNUNET_free (dns_ip);
1971   vpn_handle = GNUNET_VPN_connect (cfg);
1972 }
1973
1974
1975 /**
1976  * Shutdown resolver
1977  */
1978 void
1979 GNS_resolver_done ()
1980 {
1981   struct GNS_ResolverHandle *rh;
1982
1983   /* abort active resolutions */
1984   while (NULL != (rh = rlh_head))
1985   {
1986     rh->proc (rh->proc_cls, 0, NULL);
1987     GNS_resolver_lookup_cancel (rh);
1988   }
1989   GNUNET_CONTAINER_heap_destroy (dht_lookup_heap);
1990   dht_lookup_heap = NULL;
1991   GNUNET_DNSSTUB_stop (dns_handle);
1992   dns_handle = NULL;
1993   GNUNET_VPN_disconnect (vpn_handle);
1994   vpn_handle = NULL;
1995   dht_handle = NULL;
1996   namestore_handle = NULL;
1997 }
1998
1999
2000 /* *************** common helper functions (do not really belong here) *********** */
2001
2002 /**
2003  * Checks if @a name ends in ".TLD"
2004  *
2005  * @param name the name to check
2006  * @param tld the TLD to check for
2007  * @return GNUNET_YES or GNUNET_NO
2008  */
2009 int
2010 is_tld (const char* name, const char* tld)
2011 {
2012   size_t offset = 0;
2013
2014   if (strlen (name) <= strlen (tld))
2015     return GNUNET_NO;
2016   offset = strlen (name) - strlen (tld);
2017   if (0 != strcmp (name + offset, tld))
2018     return GNUNET_NO;
2019   return GNUNET_YES;
2020 }
2021
2022
2023 /* end of gnunet-service-gns_resolver.c */