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_EccPublicKey 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_EccPublicKey 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     }
 581     rh->proc (rh->proc_cls,
 582               n,
 583               rd);
 584   }
 585   GNS_resolver_lookup_cancel (rh);
 586 }
 587
 588
 589 /**
 590  * Add a result from DNS to the records to be returned to the application.
 591  *
 592  * @param rh resolution request to extend with a result
 593  * @param expiration_time expiration time for the answer
 594  * @param record_type DNS record type of the answer
 595  * @param data_size number of bytes in @a data
 596  * @param data binary data to return in DNS record
 597  */
 598 static void
 599 add_dns_result (struct GNS_ResolverHandle *rh,
 600                 uint64_t expiration_time,
 601                 uint32_t record_type,
 602                 size_t data_size,
 603                 const void *data)
 604 {
 605   struct DnsResult *res;
 606
 607   res = GNUNET_malloc (sizeof (struct DnsResult) + data_size);
 608   res->expiration_time = expiration_time;
 609   res->data_size = data_size;
 610   res->record_type = record_type;
 611   res->data = &res[1];
 612   memcpy (&res[1], data, data_size);
 613   GNUNET_CONTAINER_DLL_insert (rh->dns_result_head,
 614                                rh->dns_result_tail,
 615                                res);
 616 }
 617
 618
 619 /**
 620  * We had to do a DNS lookup.  Convert the result (if any) and return
 621  * it.
 622  *
 623  * @param cls closure with the 'struct GNS_ResolverHandle'
 624  * @param addr one of the addresses of the host, NULL for the last address
 625  * @param addrlen length of the address
 626  */
 627 static void
 628 handle_dns_result (void *cls,
 629                    const struct sockaddr *addr,
 630                    socklen_t addrlen)
 631 {
 632   struct GNS_ResolverHandle *rh = cls;
 633   const struct sockaddr_in *sa4;
 634   const struct sockaddr_in6 *sa6;
 635
 636   rh->std_resolve = NULL;
 637   if (NULL == addr)
 638   {
 639     transmit_lookup_dns_result (rh);
 640     return;
 641   }
 642   switch (addr->sa_family)
 643   {
 644   case AF_INET:
 645     sa4 = (const struct sockaddr_in *) addr;
 646     add_dns_result (rh,
 647                     0 /* expiration time is unknown */,
 648                     GNUNET_DNSPARSER_TYPE_A,
 649                     sizeof (struct in_addr),
 650                     &sa4->sin_addr);
 651     break;
 652   case AF_INET6:
 653     sa6 = (const struct sockaddr_in6 *) addr;
 654     add_dns_result (rh,
 655                     0 /* expiration time is unknown */,
 656                     GNUNET_DNSPARSER_TYPE_AAAA,
 657                     sizeof (struct in6_addr),
 658                     &sa6->sin6_addr);
 659     break;
 660   default:
 661     GNUNET_break (0);
 662     break;
 663   }
 664 }
 665
 666
 667 /**
 668  * Task scheduled to continue with the resolution process.
 669  *
 670  * @param cls the 'struct GNS_ResolverHandle' of the resolution
 671  * @param tc task context
 672  */
 673 static void
 674 recursive_resolution (void *cls,
 675                       const struct GNUNET_SCHEDULER_TaskContext *tc);
 676
 677
 678 /**
 679  * Begin the resolution process from 'name', starting with
 680  * the identification of the zone specified by 'name'.
 681  *
 682  * @param rh resolution to perform
 683  */
 684 static void
 685 start_resolver_lookup (struct GNS_ResolverHandle *rh);
 686
 687
 688 /**
 689  * Function called with the result of a DNS resolution.
 690  *
 691  * @param cls the request handle of the resolution that
 692  *        we were attempting to make
 693  * @param rs socket that received the response
 694  * @param dns dns response, never NULL
 695  * @param dns_len number of bytes in @a dns
 696  */
 697 static void
 698 dns_result_parser (void *cls,
 699                    struct GNUNET_DNSSTUB_RequestSocket *rs,
 700                    const struct GNUNET_TUN_DnsHeader *dns,
 701                    size_t dns_len)
 702 {
 703   struct GNS_ResolverHandle *rh = cls;
 704   struct GNUNET_DNSPARSER_Packet *p;
 705   const struct GNUNET_DNSPARSER_Record *rec;
 706   unsigned int rd_count;
 707   unsigned int i;
 708
 709   rh->dns_request = NULL;
 710   GNUNET_SCHEDULER_cancel (rh->task_id);
 711   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
 712   p = GNUNET_DNSPARSER_parse ((const char *) dns,
 713                               dns_len);
 714   if (NULL == p)
 715   {
 716     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
 717                 _("Failed to parse DNS response\n"));
 718     rh->proc (rh->proc_cls, 0, NULL);
 719     GNS_resolver_lookup_cancel (rh);
 720     return;
 721   }
 722
 723   if ( (p->num_answers > 0) &&
 724        (GNUNET_DNSPARSER_TYPE_CNAME == p->answers[0].type) &&
 725        (GNUNET_DNSPARSER_TYPE_CNAME != rh->record_type) )
 726     {
 727       GNUNET_free (rh->name);
 728       rh->name = GNUNET_strdup (p->answers[0].data.hostname);
 729       start_resolver_lookup (rh);
 730       GNUNET_DNSPARSER_free_packet (p);
 731       return;
 732     }
 733   /* FIXME: add DNAME support */
 734
 735   /* convert from (parsed) DNS to (binary) GNS format! */
 736   rd_count = p->num_answers + p->num_authority_records + p->num_additional_records;
 737   {
 738     struct GNUNET_NAMESTORE_RecordData rd[rd_count];
 739     unsigned int skip;
 740     char buf[UINT16_MAX];
 741     size_t buf_off;
 742
 743     buf_off = 0;
 744     skip = 0;
 745     memset (rd, 0, sizeof (rd));
 746     for (i=0;i<rd_count;i++)
 747     {
 748       if (i < p->num_answers)
 749         rec = &p->answers[i];
 750       else if (i < p->num_answers + p->num_authority_records)
 751         rec = &p->authority_records[i - p->num_answers];
 752       else
 753         rec = &p->authority_records[i - p->num_answers - p->num_authority_records];
 754       /* As we copied the full DNS name to 'rh->ac_tail->label', this
 755          should be the correct check to see if this record is actually
 756          a record for our label... */
 757       if (0 != strcmp (rec->name,
 758                        rh->ac_tail->label))
 759       {
 760         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 761                     "Dropping record `%s', does not match desired name `%s'\n",
 762                     rec->name,
 763                     rh->ac_tail->label);
 764         skip++;
 765         continue;
 766       }
 767       rd[i - skip].record_type = rec->type;
 768       rd[i - skip].expiration_time = rec->expiration_time.abs_value_us;
 769       switch (rec->type)
 770       {
 771       case GNUNET_DNSPARSER_TYPE_A:
 772         if (rec->data.raw.data_len != sizeof (struct in_addr))
 773         {
 774           GNUNET_break_op (0);
 775           skip++;
 776           continue;
 777         }
 778         rd[i - skip].data_size = rec->data.raw.data_len;
 779         rd[i - skip].data = rec->data.raw.data;
 780         break;
 781       case GNUNET_DNSPARSER_TYPE_AAAA:
 782         if (rec->data.raw.data_len != sizeof (struct in6_addr))
 783         {
 784           GNUNET_break_op (0);
 785           skip++;
 786           continue;
 787         }
 788         rd[i - skip].data_size = rec->data.raw.data_len;
 789         rd[i - skip].data = rec->data.raw.data;
 790         break;
 791       case GNUNET_DNSPARSER_TYPE_CNAME:
 792       case GNUNET_DNSPARSER_TYPE_PTR:
 793       case GNUNET_DNSPARSER_TYPE_NS:
 794         if (GNUNET_OK !=
 795             GNUNET_DNSPARSER_builder_add_name (buf,
 796                                                sizeof (buf),
 797                                                &buf_off,
 798                                                rec->data.hostname))
 799         {
 800           GNUNET_break (0);
 801           skip++;
 802           continue;
 803         }
 804         break;
 805       case GNUNET_DNSPARSER_TYPE_SOA:
 806         if (GNUNET_OK !=
 807             GNUNET_DNSPARSER_builder_add_soa (buf,
 808                                                sizeof (buf),
 809                                                &buf_off,
 810                                                rec->data.soa))
 811         {
 812           GNUNET_break (0);
 813           skip++;
 814           continue;
 815         }
 816         break;
 817       case GNUNET_DNSPARSER_TYPE_MX:
 818         if (GNUNET_OK !=
 819             GNUNET_DNSPARSER_builder_add_mx (buf,
 820                                              sizeof (buf),
 821                                              &buf_off,
 822                                              rec->data.mx))
 823         {
 824           GNUNET_break (0);
 825           skip++;
 826           continue;
 827         }
 828         break;
 829       case GNUNET_DNSPARSER_TYPE_SRV:
 830         if (GNUNET_OK !=
 831             GNUNET_DNSPARSER_builder_add_srv (buf,
 832                                               sizeof (buf),
 833                                               &buf_off,
 834                                               rec->data.srv))
 835         {
 836           GNUNET_break (0);
 837           skip++;
 838           continue;
 839         }
 840         break;
 841       default:
 842         GNUNET_log (GNUNET_ERROR_TYPE_INFO,
 843                     _("Skipping record of unsupported type %d\n"),
 844                     rec->type);
 845         skip++;
 846         continue;
 847       }
 848     }
 849     rh->proc (rh->proc_cls, rd_count - skip, rd);
 850     GNS_resolver_lookup_cancel (rh);
 851   }
 852   GNUNET_DNSPARSER_free_packet (p);
 853 }
 854
 855
 856 /**
 857  * Perform recursive DNS resolution.  Asks the given DNS resolver to
 858  * resolve "rh->dns_name", possibly recursively proceeding following
 859  * NS delegations, CNAMES, etc., until 'rh->loop_limiter' bounds us or
 860  * we find the answer.
 861  *
 862  * @param rh resolution information
 863  */
 864 static void
 865 recursive_dns_resolution (struct GNS_ResolverHandle *rh)
 866 {
 867   struct AuthorityChain *ac;
 868   socklen_t sa_len;
 869   struct GNUNET_DNSPARSER_Query *query;
 870   struct GNUNET_DNSPARSER_Packet *p;
 871   char *dns_request;
 872   size_t dns_request_length;
 873
 874   ac = rh->ac_tail;
 875   GNUNET_assert (NULL != ac);
 876   GNUNET_assert (GNUNET_NO == ac->gns_authority);
 877   switch (((const struct sockaddr *) &ac->authority_info.dns_authority.dns_ip)->sa_family)
 878   {
 879   case AF_INET:
 880     sa_len = sizeof (struct sockaddr_in);
 881     break;
 882   case AF_INET6:
 883     sa_len = sizeof (struct sockaddr_in6);
 884     break;
 885   default:
 886     GNUNET_break (0);
 887     rh->proc (rh->proc_cls, 0, NULL);
 888     GNS_resolver_lookup_cancel (rh);
 889     return;
 890   }
 891   query = GNUNET_new (struct GNUNET_DNSPARSER_Query);
 892   query->name = GNUNET_strdup (ac->label);
 893   query->type = rh->record_type;
 894   query->class = GNUNET_TUN_DNS_CLASS_INTERNET;
 895   p = GNUNET_new (struct GNUNET_DNSPARSER_Packet);
 896   p->queries = query;
 897   p->num_queries = 1;
 898   p->id = (uint16_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
 899                                                UINT16_MAX);
 900   p->flags.opcode = GNUNET_TUN_DNS_OPCODE_QUERY;
 901   p->flags.recursion_desired = 1;
 902   if (GNUNET_OK !=
 903       GNUNET_DNSPARSER_pack (p, 1024, &dns_request, &dns_request_length))
 904   {
 905     GNUNET_break (0);
 906     rh->proc (rh->proc_cls, 0, NULL);
 907     GNS_resolver_lookup_cancel (rh);
 908   }
 909   else
 910   {
 911     rh->dns_request = GNUNET_DNSSTUB_resolve (dns_handle,
 912                                               (const struct sockaddr *) &ac->authority_info.dns_authority.dns_ip,
 913                                               sa_len,
 914                                               dns_request,
 915                                               dns_request_length,
 916                                               &dns_result_parser,
 917                                               rh);
 918     rh->task_id = GNUNET_SCHEDULER_add_delayed (DNS_LOOKUP_TIMEOUT,
 919                                                 &fail_resolution,
 920                                                 rh);
 921   }
 922   GNUNET_free (dns_request);
 923   GNUNET_DNSPARSER_free_packet (p);
 924 }
 925
 926
 927 /**
 928  * We encountered a CNAME record during our resolution.
 929  * Merge it into our chain.
 930  *
 931  * @param rh resolution we are performing
 932  * @param cname value of the cname record we got for the current
 933  *        authority chain tail
 934  */
 935 static void
 936 handle_gns_cname_result (struct GNS_ResolverHandle *rh,
 937                          const char *cname)
 938 {
 939   size_t nlen;
 940   char *res;
 941
 942   nlen = strlen (cname);
 943   if ( (nlen > 2) &&
 944        (0 == strcmp (".+",
 945                      &cname[nlen - 2])) )
 946   {
 947     /* CNAME resolution continues relative to current domain */
 948     if (0 == rh->name_resolution_pos)
 949     {
 950       res = GNUNET_strndup (cname, nlen - 2);
 951       rh->name_resolution_pos = nlen - 2;
 952     }
 953     else
 954     {
 955       GNUNET_asprintf (&res,
 956                        "%.*s.%.*s",
 957                        (int) rh->name_resolution_pos,
 958                        rh->name,
 959                        (int) (nlen - 2),
 960                        cname);
 961       rh->name_resolution_pos = strlen (res);
 962     }
 963     GNUNET_free (rh->name);
 964     rh->name = res;
 965     rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
 966                                             rh);
 967     return;
 968   }
 969   /* name is absolute, start from the beginning */
 970   GNUNET_free (rh->name);
 971   rh->name = GNUNET_strdup (cname);
 972   start_resolver_lookup (rh);
 973 }
 974
 975
 976 /**
 977  * Process a records that were decrypted from a block.
 978  *
 979  * @param cls closure with the 'struct GNS_ResolverHandle'
 980  * @param rd_count number of entries in @a rd array
 981  * @param rd array of records with data to store
 982  */
 983 static void
 984 handle_gns_resolution_result (void *cls,
 985                               unsigned int rd_count,
 986                               const struct GNUNET_NAMESTORE_RecordData *rd);
 987
 988
 989 /**
 990  * Callback invoked from the VPN service once a redirection is
 991  * available.  Provides the IP address that can now be used to
 992  * reach the requested destination.  Replaces the "VPN" record
 993  * with the respective A/AAAA record and continues processing.
 994  *
 995  * @param cls closure
 996  * @param af address family, AF_INET or AF_INET6; AF_UNSPEC on error;
 997  *                will match 'result_af' from the request
 998  * @param address IP address (struct in_addr or struct in_addr6, depending on 'af')
 999  *                that the VPN allocated for the redirection;
1000  *                traffic to this IP will now be redirected to the
1001  *                specified target peer; NULL on error
1002  */
1003 static void
1004 vpn_allocation_cb (void *cls,
1005                    int af,
1006                    const void *address)
1007 {
1008   struct VpnContext *vpn_ctx = cls;
1009   struct GNS_ResolverHandle *rh = vpn_ctx->rh;
1010   struct GNUNET_NAMESTORE_RecordData rd[vpn_ctx->rd_count];
1011   unsigned int i;
1012
1013   vpn_ctx->vpn_request = NULL;
1014   rh->vpn_ctx = NULL;
1015   GNUNET_assert (GNUNET_OK ==
1016                  GNUNET_NAMESTORE_records_deserialize (vpn_ctx->rd_data_size,
1017                                                        vpn_ctx->rd_data,
1018                                                        vpn_ctx->rd_count,
1019                                                        rd));
1020   for (i=0;i<vpn_ctx->rd_count;i++)
1021   {
1022     if (GNUNET_NAMESTORE_TYPE_VPN == rd[i].record_type)
1023     {
1024       switch (af)
1025       {
1026       case AF_INET:
1027         rd[i].record_type = GNUNET_DNSPARSER_TYPE_A;
1028         rd[i].data_size = sizeof (struct in_addr);
1029         rd[i].expiration_time = GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT).abs_value_us;
1030         rd[i].flags = 0;
1031         rd[i].data = address;
1032         break;
1033       case AF_INET6:
1034         rd[i].record_type = GNUNET_DNSPARSER_TYPE_AAAA;
1035         rd[i].expiration_time = GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT).abs_value_us;
1036         rd[i].flags = 0;
1037         rd[i].data = address;
1038         rd[i].data_size = sizeof (struct in6_addr);
1039         break;
1040       default:
1041         GNUNET_assert (0);
1042       }
1043       break;
1044     }
1045   }
1046   GNUNET_assert (i < vpn_ctx->rd_count);
1047   handle_gns_resolution_result (rh,
1048                                 vpn_ctx->rd_count,
1049                                 rd);
1050   GNUNET_free (vpn_ctx->rd_data);
1051   GNUNET_free (vpn_ctx);
1052 }
1053
1054
1055 /**
1056  * Process a records that were decrypted from a block.
1057  *
1058  * @param cls closure with the 'struct GNS_ResolverHandle'
1059  * @param rd_count number of entries in @a rd array
1060  * @param rd array of records with data to store
1061  */
1062 static void
1063 handle_gns_resolution_result (void *cls,
1064                               unsigned int rd_count,
1065                               const struct GNUNET_NAMESTORE_RecordData *rd)
1066 {
1067   struct GNS_ResolverHandle *rh = cls;
1068   struct AuthorityChain *ac;
1069   unsigned int i;
1070   unsigned int j;
1071   struct sockaddr *sa;
1072   struct sockaddr_in v4;
1073   struct sockaddr_in6 v6;
1074   size_t sa_len;
1075   char *cname;
1076   struct VpnContext *vpn_ctx;
1077   const struct GNUNET_TUN_GnsVpnRecord *vpn;
1078   const char *vname;
1079   struct GNUNET_HashCode vhash;
1080   int af;
1081   char scratch[UINT16_MAX];
1082   size_t scratch_off;
1083   size_t scratch_start;
1084   size_t off;
1085   struct GNUNET_NAMESTORE_RecordData rd_new[rd_count];
1086   unsigned int rd_off;
1087
1088   if (0 == rh->name_resolution_pos)
1089   {
1090     /* top-level match, are we done yet? */
1091     if ( (rd_count > 0) &&
1092          (GNUNET_DNSPARSER_TYPE_CNAME == rd[0].record_type) &&
1093          (GNUNET_DNSPARSER_TYPE_CNAME != rh->record_type) )
1094     {
1095       cname = GNUNET_strndup (rd[0].data,
1096                               rd[0].data_size);
1097       handle_gns_cname_result (rh,
1098                                cname);
1099       GNUNET_free (cname);
1100       return;
1101     }
1102     /* If A/AAAA was requested, but we got a VPN
1103        record, we convert it to A/AAAA using GNUnet VPN */
1104     if ( (GNUNET_DNSPARSER_TYPE_A == rh->record_type) ||
1105          (GNUNET_DNSPARSER_TYPE_AAAA == rh->record_type) )
1106     {
1107       for (i=0;i<rd_count;i++)
1108       {
1109         if (GNUNET_NAMESTORE_TYPE_VPN == rd[i].record_type)
1110         {
1111           af = (GNUNET_DNSPARSER_TYPE_A == rh->record_type) ? AF_INET : AF_INET6;
1112           if (sizeof (struct GNUNET_TUN_GnsVpnRecord) <
1113               rd[i].data_size)
1114           {
1115             GNUNET_break_op (0);
1116             rh->proc (rh->proc_cls, 0, NULL);
1117             GNS_resolver_lookup_cancel (rh);
1118             return;
1119           }
1120           vpn = (const struct GNUNET_TUN_GnsVpnRecord *) rd[i].data;
1121           vname = (const char *) &vpn[1];
1122           if ('\0' != vname[rd[i].data_size - 1 - sizeof (struct GNUNET_TUN_GnsVpnRecord)])
1123           {
1124             GNUNET_break_op (0);
1125             rh->proc (rh->proc_cls, 0, NULL);
1126             GNS_resolver_lookup_cancel (rh);
1127             return;
1128           }
1129           GNUNET_CRYPTO_hash (vname,
1130                               strlen (vname), // FIXME: +1?
1131                               &vhash);
1132           vpn_ctx = GNUNET_new (struct VpnContext);
1133           rh->vpn_ctx = vpn_ctx;
1134           vpn_ctx->rh = rh;
1135           vpn_ctx->rd_data_size = GNUNET_NAMESTORE_records_get_size (rd_count,
1136                                                                      rd);
1137           vpn_ctx->rd_data = GNUNET_malloc (vpn_ctx->rd_data_size);
1138           (void) GNUNET_NAMESTORE_records_serialize (rd_count,
1139                                                      rd,
1140                                                      vpn_ctx->rd_data_size,
1141                                                      vpn_ctx->rd_data);
1142           vpn_ctx->vpn_request = GNUNET_VPN_redirect_to_peer (vpn_handle,
1143                                                               af,
1144                                                               ntohs (vpn->proto),
1145                                                               &vpn->peer,
1146                                                               &vhash,
1147                                                               GNUNET_NO,
1148                                                               GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT),
1149                                                               &vpn_allocation_cb,
1150                                                               rh);
1151           return;
1152         }
1153       }
1154     }
1155     /* convert relative names in record values to absolute names,
1156        using 'scratch' array for memory allocations */
1157     scratch_off = 0;
1158     rd_off = 0;
1159     for (i=0;i<rd_count;i++)
1160     {
1161       rd_new[rd_off] = rd[i];
1162       /* Check if the embedded name(s) end in "+", and if so,
1163          replace the "+" with the zone at "ac_tail", changing the name
1164          to a ".zkey".  The name is allocated on the 'scratch' array,
1165          so we can free it afterwards. */
1166       switch (rd[i].record_type)
1167       {
1168       case GNUNET_DNSPARSER_TYPE_CNAME:
1169         {
1170           char *cname;
1171
1172           off = 0;
1173           cname = GNUNET_DNSPARSER_parse_name (rd[i].data,
1174                                                rd[i].data_size,
1175                                                &off);
1176           if ( (NULL == cname) ||
1177                (off != rd[i].data_size) )
1178           {
1179             GNUNET_break_op (0); /* record not well-formed */
1180           }
1181           else
1182           {
1183             cname = translate_dot_plus (rh, cname);
1184             scratch_start = scratch_off;
1185             if (GNUNET_OK !=
1186                 GNUNET_DNSPARSER_builder_add_name (scratch,
1187                                                    sizeof (scratch),
1188                                                    &scratch_off,
1189                                                    cname))
1190             {
1191               GNUNET_break (0);
1192             }
1193             else
1194             {
1195               rd_new[rd_off].data = &scratch[scratch_start];
1196               rd_new[rd_off].data_size = scratch_off - scratch_start;
1197               rd_off++;
1198             }
1199           }
1200           GNUNET_free_non_null (cname);
1201         }
1202         break;
1203       case GNUNET_DNSPARSER_TYPE_SOA:
1204         {
1205           struct GNUNET_DNSPARSER_SoaRecord *soa;
1206
1207           off = 0;
1208           soa = GNUNET_DNSPARSER_parse_soa (rd[i].data,
1209                                             rd[i].data_size,
1210                                             &off);
1211           if ( (NULL == soa) ||
1212                (off != rd[i].data_size) )
1213           {
1214             GNUNET_break_op (0); /* record not well-formed */
1215           }
1216           else
1217           {
1218             soa->mname = translate_dot_plus (rh, soa->mname);
1219             soa->rname = translate_dot_plus (rh, soa->rname);
1220             scratch_start = scratch_off;
1221             if (GNUNET_OK !=
1222                 GNUNET_DNSPARSER_builder_add_soa (scratch,
1223                                                   sizeof (scratch),
1224                                                   &scratch_off,
1225                                                   soa))
1226             {
1227               GNUNET_break (0);
1228             }
1229             else
1230             {
1231               rd_new[rd_off].data = &scratch[scratch_start];
1232               rd_new[rd_off].data_size = scratch_off - scratch_start;
1233               rd_off++;
1234             }
1235           }
1236           if (NULL != soa)
1237             GNUNET_DNSPARSER_free_soa (soa);
1238         }
1239         break;
1240       case GNUNET_DNSPARSER_TYPE_MX:
1241         {
1242           struct GNUNET_DNSPARSER_MxRecord *mx;
1243
1244           off = 0;
1245           mx = GNUNET_DNSPARSER_parse_mx (rd[i].data,
1246                                           rd[i].data_size,
1247                                           &off);
1248           if ( (NULL == mx) ||
1249                (off != rd[i].data_size) )
1250           {
1251             GNUNET_break_op (0); /* record not well-formed */
1252           }
1253           else
1254           {
1255             mx->mxhost = translate_dot_plus (rh, mx->mxhost);
1256             scratch_start = scratch_off;
1257             if (GNUNET_OK !=
1258                 GNUNET_DNSPARSER_builder_add_mx (scratch,
1259                                                  sizeof (scratch),
1260                                                  &scratch_off,
1261                                                  mx))
1262             {
1263               GNUNET_break (0);
1264             }
1265             else
1266             {
1267               rd_new[rd_off].data = &scratch[scratch_start];
1268               rd_new[rd_off].data_size = scratch_off - scratch_start;
1269               rd_off++;
1270             }
1271           }
1272           if (NULL != mx)
1273             GNUNET_DNSPARSER_free_mx (mx);
1274         }
1275         break;
1276       case GNUNET_DNSPARSER_TYPE_SRV:
1277         {
1278           struct GNUNET_DNSPARSER_SrvRecord *srv;
1279
1280           off = 0;
1281           /* FIXME: passing rh->name here is is not necessarily what we want
1282              (SRV support not finished) */
1283           srv = GNUNET_DNSPARSER_parse_srv (rh->name,
1284                                             rd[i].data,
1285                                             rd[i].data_size,
1286                                             &off);
1287           if ( (NULL == srv) ||
1288                (off != rd[i].data_size) )
1289           {
1290             GNUNET_break_op (0); /* record not well-formed */
1291           }
1292           else
1293           {
1294             srv->domain_name = translate_dot_plus (rh, srv->domain_name);
1295             srv->target = translate_dot_plus (rh, srv->target);
1296             scratch_start = scratch_off;
1297             if (GNUNET_OK !=
1298                 GNUNET_DNSPARSER_builder_add_srv (scratch,
1299                                                   sizeof (scratch),
1300                                                   &scratch_off,
1301                                                   srv))
1302             {
1303               GNUNET_break (0);
1304             }
1305             else
1306             {
1307               rd_new[rd_off].data = &scratch[scratch_start];
1308               rd_new[rd_off].data_size = scratch_off - scratch_start;
1309               rd_off++;
1310             }
1311           }
1312           if (NULL != srv)
1313             GNUNET_DNSPARSER_free_srv (srv);
1314         }
1315         break;
1316       case GNUNET_NAMESTORE_TYPE_PKEY:
1317         /* tigger shortening */
1318         if (NULL != rh->shorten_key)
1319         {
1320           struct GNUNET_CRYPTO_EccPublicKey pub;
1321
1322           if (rd[i].data_size != sizeof (struct GNUNET_CRYPTO_EccPublicKey))
1323           {
1324             GNUNET_break_op (0);
1325             break;
1326           }
1327           memcpy (&pub, rd[i].data, rd[i].data_size);
1328           GNS_shorten_start (rh->ac_tail->label,
1329                              &pub,
1330                              rh->shorten_key);
1331         }
1332       default:
1333         break;
1334       }
1335     }
1336
1337     /* yes, we are done, return result */
1338     rh->proc (rh->proc_cls, rd_off, rd_new);
1339     GNS_resolver_lookup_cancel (rh);
1340     return;
1341   }
1342   /* need to recurse, check if we can */
1343   for (i=0;i<rd_count;i++)
1344   {
1345     switch (rd[i].record_type)
1346     {
1347     case GNUNET_NAMESTORE_TYPE_PKEY:
1348       /* delegation to another zone */
1349       if (sizeof (struct GNUNET_CRYPTO_EccPublicKey) !=
1350           rd[i].data_size)
1351       {
1352         GNUNET_break_op (0);
1353         rh->proc (rh->proc_cls, 0, NULL);
1354         GNS_resolver_lookup_cancel (rh);
1355         return;
1356       }
1357       /* expand authority chain */
1358       ac = GNUNET_new (struct AuthorityChain);
1359       ac->rh = rh;
1360       ac->gns_authority = GNUNET_YES;
1361       memcpy (&ac->authority_info.gns_authority,
1362               rd[i].data,
1363               sizeof (struct GNUNET_CRYPTO_EccPublicKey));
1364       ac->label = resolver_lookup_get_next_label (rh);
1365       /* tigger shortening */
1366       if (NULL != rh->shorten_key)
1367         GNS_shorten_start (rh->ac_tail->label,
1368                            &ac->authority_info.gns_authority,
1369                            rh->shorten_key);
1370       /* add AC to tail */
1371       GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1372                                         rh->ac_tail,
1373                                         ac);
1374       /* recurse */
1375       rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1376                                               rh);
1377       break;
1378     case GNUNET_DNSPARSER_TYPE_NS:
1379       /* resolution continues within DNS */
1380       if (GNUNET_DNSPARSER_MAX_NAME_LENGTH < rd[i].data_size)
1381       {
1382         GNUNET_break_op (0);
1383         rh->proc (rh->proc_cls, 0, NULL);
1384         GNS_resolver_lookup_cancel (rh);
1385         return;
1386       }
1387       /* find associated A/AAAA record */
1388       sa = NULL;
1389       sa_len = 0;
1390       for (j=0;j<rd_count;j++)
1391       {
1392         switch (rd[j].record_type)
1393         {
1394         case GNUNET_DNSPARSER_TYPE_A:
1395           if (sizeof (struct in_addr) != rd[i].data_size)
1396           {
1397             GNUNET_break_op (0);
1398             rh->proc (rh->proc_cls, 0, NULL);
1399             GNS_resolver_lookup_cancel (rh);
1400             return;
1401           }
1402           /* FIXME: might want to check if we support IPv4 here,
1403              and otherwise skip this one and hope we find another */
1404           memset (&v4, 0, sizeof (v4));
1405           sa_len = sizeof (v4);
1406           v4.sin_family = AF_INET;
1407           v4.sin_port = htons (53);
1408 #if HAVE_SOCKADDR_IN_SIN_LEN
1409           v4.sin_len = (u_char) sa_len;
1410 #endif
1411           memcpy (&v4.sin_addr,
1412                   rd[j].data,
1413                   sizeof (struct in_addr));
1414           sa = (struct sockaddr *) &v4;
1415           break;
1416         case GNUNET_DNSPARSER_TYPE_AAAA:
1417           if (sizeof (struct in6_addr) != rd[i].data_size)
1418           {
1419             GNUNET_break_op (0);
1420             rh->proc (rh->proc_cls, 0, NULL);
1421             GNS_resolver_lookup_cancel (rh);
1422             return;
1423           }
1424           /* FIXME: might want to check if we support IPv6 here,
1425              and otherwise skip this one and hope we find another */
1426           memset (&v6, 0, sizeof (v6));
1427           sa_len = sizeof (v6);
1428           v6.sin6_family = AF_INET6;
1429           v6.sin6_port = htons (53);
1430 #if HAVE_SOCKADDR_IN_SIN_LEN
1431           v6.sin6_len = (u_char) sa_len;
1432 #endif
1433           memcpy (&v6.sin6_addr,
1434                   rd[j].data,
1435                   sizeof (struct in6_addr));
1436           sa = (struct sockaddr *) &v6;
1437           break;
1438         default:
1439           break;
1440         }
1441         if (NULL != sa)
1442           break;
1443       }
1444       if (NULL == sa)
1445       {
1446         /* we cannot continue; NS without A/AAAA */
1447         rh->proc (rh->proc_cls, 0, NULL);
1448         GNS_resolver_lookup_cancel (rh);
1449         return;
1450       }
1451       /* expand authority chain */
1452       ac = GNUNET_new (struct AuthorityChain);
1453       ac->rh = rh;
1454       strncpy (ac->authority_info.dns_authority.name,
1455                rd[i].data,
1456                rd[i].data_size);
1457       ac->authority_info.dns_authority.name[rd[i].data_size] = '\0';
1458       memcpy (&ac->authority_info.dns_authority.dns_ip,
1459               sa,
1460               sa_len);
1461       /* for DNS recursion, the label is the full DNS name,
1462          created from the remainder of the GNS name and the
1463          name in the NS record */
1464       GNUNET_asprintf (&ac->label,
1465                        "%.*s%s",
1466                        (int) rh->name_resolution_pos,
1467                        rh->name,
1468                        ac->authority_info.dns_authority.name);
1469       GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1470                                         rh->ac_tail,
1471                                         ac);
1472       if (strlen (ac->label) > GNUNET_DNSPARSER_MAX_NAME_LENGTH)
1473       {
1474         GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1475                     _("GNS lookup resulted in DNS name that is too long (`%s')\n"),
1476                     ac->label);
1477         rh->proc (rh->proc_cls, 0, NULL);
1478         GNS_resolver_lookup_cancel (rh);
1479         return;
1480       }
1481       /* recurse */
1482       rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1483                                               rh);
1484       return;
1485     case GNUNET_DNSPARSER_TYPE_CNAME:
1486       cname = GNUNET_strndup (rd[i].data,
1487                               rd[i].data_size);
1488       handle_gns_cname_result (rh,
1489                                cname);
1490       GNUNET_free (cname);
1491       return;
1492       /* FIXME: handle DNAME */
1493     default:
1494       /* skip */
1495       break;
1496     }
1497   }
1498   GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1499               _("GNS lookup recursion failed (no delegation record found)\n"));
1500   rh->proc (rh->proc_cls, 0, NULL);
1501   GNS_resolver_lookup_cancel (rh);
1502 }
1503
1504
1505 /**
1506  * Function called once the namestore has completed the request for
1507  * caching a block.
1508  *
1509  * @param cls closure with the 'struct GNS_ResolverHandle'
1510  * @param success #GNUNET_OK on success
1511  * @param emsg error message
1512  */
1513 static void
1514 namestore_cache_continuation (void *cls,
1515                               int32_t success,
1516                               const char *emsg)
1517 {
1518   struct GNS_ResolverHandle *rh = cls;
1519
1520   rh->namestore_qe = NULL;
1521   if (NULL != emsg)
1522     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1523                 _("Failed to cache GNS resolution: %s\n"),
1524                 emsg);
1525 }
1526
1527
1528 /**
1529  * Iterator called on each result obtained for a DHT
1530  * operation that expects a reply
1531  *
1532  * @param cls closure with the 'struct GNS_ResolverHandle'
1533  * @param exp when will this value expire
1534  * @param key key of the result
1535  * @param get_path peers on reply path (or NULL if not recorded)
1536  *                 [0] = datastore's first neighbor, [length - 1] = local peer
1537  * @param get_path_length number of entries in get_path
1538  * @param put_path peers on the PUT path (or NULL if not recorded)
1539  *                 [0] = origin, [length - 1] = datastore
1540  * @param put_path_length number of entries in get_path
1541  * @param type type of the result
1542  * @param size number of bytes in data
1543  * @param data pointer to the result data
1544  */
1545 static void
1546 handle_dht_response (void *cls,
1547                      struct GNUNET_TIME_Absolute exp,
1548                      const struct GNUNET_HashCode * key,
1549                      const struct GNUNET_PeerIdentity *get_path,
1550                      unsigned int get_path_length,
1551                      const struct GNUNET_PeerIdentity *put_path,
1552                      unsigned int put_path_length,
1553                      enum GNUNET_BLOCK_Type type,
1554                      size_t size, const void *data)
1555 {
1556   struct GNS_ResolverHandle *rh = cls;
1557   struct AuthorityChain *ac = rh->ac_tail;
1558   const struct GNUNET_NAMESTORE_Block *block;
1559
1560   GNUNET_DHT_get_stop (rh->get_handle);
1561   rh->get_handle = NULL;
1562   GNUNET_CONTAINER_heap_remove_node (rh->dht_heap_node);
1563   rh->dht_heap_node = NULL;
1564   if (size < sizeof (struct GNUNET_NAMESTORE_Block))
1565   {
1566     /* how did this pass DHT block validation!? */
1567     GNUNET_break (0);
1568     rh->proc (rh->proc_cls, 0, NULL);
1569     GNS_resolver_lookup_cancel (rh);
1570     return;
1571   }
1572   block = data;
1573   if (size !=
1574       ntohs (block->purpose.size) +
1575       sizeof (struct GNUNET_CRYPTO_EccPublicKey) +
1576       sizeof (struct GNUNET_CRYPTO_EccSignature))
1577   {
1578     /* how did this pass DHT block validation!? */
1579     GNUNET_break (0);
1580     rh->proc (rh->proc_cls, 0, NULL);
1581     GNS_resolver_lookup_cancel (rh);
1582     return;
1583   }
1584   if (GNUNET_OK !=
1585       GNUNET_NAMESTORE_block_decrypt (block,
1586                                       &ac->authority_info.gns_authority,
1587                                       ac->label,
1588                                       &handle_gns_resolution_result,
1589                                       rh))
1590   {
1591     GNUNET_break_op (0); /* block was ill-formed */
1592     rh->proc (rh->proc_cls, 0, NULL);
1593     GNS_resolver_lookup_cancel (rh);
1594     return;
1595   }
1596   /* Cache well-formed blocks */
1597   rh->namestore_qe = GNUNET_NAMESTORE_block_cache (namestore_handle,
1598                                                    block,
1599                                                    &namestore_cache_continuation,
1600                                                    rh);
1601 }
1602
1603
1604 /**
1605  * Process a record that was stored in the namestore.
1606  *
1607  * @param cls closure with the `struct GNS_ResolverHandle`
1608  * @param block block that was stored in the namestore
1609  */
1610 static void
1611 handle_namestore_block_response (void *cls,
1612                                  const struct GNUNET_NAMESTORE_Block *block)
1613 {
1614   struct GNS_ResolverHandle *rh = cls;
1615   struct GNS_ResolverHandle *rx;
1616   struct AuthorityChain *ac = rh->ac_tail;
1617   const char *label = ac->label;
1618   const struct GNUNET_CRYPTO_EccPublicKey *auth = &ac->authority_info.gns_authority;
1619   struct GNUNET_HashCode query;
1620
1621   GNUNET_NAMESTORE_query_from_public_key (auth,
1622                                           label,
1623                                           &query);
1624   rh->namestore_qe = NULL;
1625   if ( (GNUNET_NO == rh->only_cached) &&
1626        ( (NULL == block) ||
1627          (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us) ) )
1628   {
1629     /* Namestore knows nothing; try DHT lookup */
1630     rh->get_handle = GNUNET_DHT_get_start (dht_handle,
1631                                            GNUNET_BLOCK_TYPE_GNS_NAMERECORD,
1632                                            &query,
1633                                            DHT_GNS_REPLICATION_LEVEL,
1634                                            GNUNET_DHT_RO_DEMULTIPLEX_EVERYWHERE,
1635                                            NULL, 0,
1636                                            &handle_dht_response, rh);
1637     rh->dht_heap_node = GNUNET_CONTAINER_heap_insert (dht_lookup_heap,
1638                                                       rh,
1639                                                       GNUNET_TIME_absolute_get ().abs_value_us);
1640     if (GNUNET_CONTAINER_heap_get_size (dht_lookup_heap) > max_allowed_background_queries)
1641     {
1642       /* fail longest-standing DHT request */
1643       rx = GNUNET_CONTAINER_heap_peek (dht_lookup_heap);
1644       rx->proc (rx->proc_cls, 0, NULL);
1645       GNS_resolver_lookup_cancel (rx);
1646     }
1647     return;
1648   }
1649   if ( (NULL == block) ||
1650        (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us) )
1651   {
1652     /* DHT not permitted and no local result, fail */
1653     rh->proc (rh->proc_cls, 0, NULL);
1654     GNS_resolver_lookup_cancel (rh);
1655     return;
1656   }
1657   if (GNUNET_OK !=
1658       GNUNET_NAMESTORE_block_decrypt (block,
1659                                       auth,
1660                                       label,
1661                                       &handle_gns_resolution_result,
1662                                       rh))
1663   {
1664     GNUNET_break_op (0); /* block was ill-formed */
1665     rh->proc (rh->proc_cls, 0, NULL);
1666     GNS_resolver_lookup_cancel (rh);
1667     return;
1668   }
1669 }
1670
1671
1672 /**
1673  * Lookup tail of our authority chain in the namestore.
1674  *
1675  * @param rh query we are processing
1676  */
1677 static void
1678 recursive_gns_resolution_namestore (struct GNS_ResolverHandle *rh)
1679 {
1680   struct AuthorityChain *ac = rh->ac_tail;
1681   struct GNUNET_HashCode query;
1682
1683   GNUNET_NAMESTORE_query_from_public_key (&ac->authority_info.gns_authority,
1684                                           ac->label,
1685                                           &query);
1686   rh->namestore_qe = GNUNET_NAMESTORE_lookup_block (namestore_handle,
1687                                                     &query,
1688                                                     &handle_namestore_block_response,
1689                                                     rh);
1690 }
1691
1692
1693 /**
1694  * Task scheduled to continue with the resolution process.
1695  *
1696  * @param cls the `struct GNS_ResolverHandle` of the resolution
1697  * @param tc task context
1698  */
1699 static void
1700 recursive_resolution (void *cls,
1701                       const struct GNUNET_SCHEDULER_TaskContext *tc)
1702 {
1703   struct GNS_ResolverHandle *rh = cls;
1704
1705   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
1706   if (MAX_RECURSION < rh->loop_limiter++)
1707   {
1708     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1709                 "Encountered unbounded recursion resolving `%s'\n",
1710                 rh->name);
1711     rh->proc (rh->proc_cls, 0, NULL);
1712     GNS_resolver_lookup_cancel (rh);
1713     return;
1714   }
1715   if (GNUNET_YES == rh->ac_tail->gns_authority)
1716     recursive_gns_resolution_namestore (rh);
1717   else
1718     recursive_dns_resolution (rh);
1719 }
1720
1721
1722 /**
1723  * Begin the resolution process from 'name', starting with
1724  * the identification of the zone specified by 'name'.
1725  *
1726  * @param rh resolution to perform
1727  */
1728 static void
1729 start_resolver_lookup (struct GNS_ResolverHandle *rh)
1730 {
1731   struct AuthorityChain *ac;
1732   char *x;
1733   char *y;
1734   char *pkey;
1735
1736   if ( ( (GNUNET_YES == is_canonical (rh->name)) &&
1737          (0 != strcmp (GNUNET_GNS_TLD, rh->name)) ) ||
1738        ( (GNUNET_YES != is_gnu_tld (rh->name)) &&
1739          (GNUNET_YES != is_zkey_tld (rh->name)) ) )
1740   {
1741     /* use standard DNS lookup */
1742     int af;
1743
1744     switch (rh->record_type)
1745     {
1746     case GNUNET_DNSPARSER_TYPE_A:
1747       af = AF_INET;
1748       break;
1749     case GNUNET_DNSPARSER_TYPE_AAAA:
1750       af = AF_INET6;
1751       break;
1752     default:
1753       af = AF_UNSPEC;
1754       break;
1755     }
1756     rh->std_resolve = GNUNET_RESOLVER_ip_get (rh->name,
1757                                               af,
1758                                               DNS_LOOKUP_TIMEOUT,
1759                                               &handle_dns_result,
1760                                               rh);
1761     return;
1762   }
1763   if (is_zkey_tld (rh->name))
1764   {
1765     /* Name ends with ".zkey", try to replace authority zone with zkey
1766        authority */
1767     GNUNET_free (resolver_lookup_get_next_label (rh)); /* will return "zkey" */
1768     x = resolver_lookup_get_next_label (rh); /* will return 'x' coordinate */
1769     y = resolver_lookup_get_next_label (rh); /* will return 'y' coordinate */
1770     GNUNET_asprintf (&pkey,
1771                      "%s%s",
1772                      x, y);
1773     if ( (NULL == x) ||
1774          (NULL == y) ||
1775          (GNUNET_OK !=
1776           GNUNET_CRYPTO_ecc_public_key_from_string (pkey,
1777                                                     strlen (pkey),
1778                                                     &rh->authority_zone)) )
1779     {
1780       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1781                   _("Hostname `%s' is not well-formed, resolution fails\n"),
1782                   rh->name);
1783       rh->task_id = GNUNET_SCHEDULER_add_now (&fail_resolution, rh);
1784     }
1785     GNUNET_free_non_null (x);
1786     GNUNET_free_non_null (y);
1787     GNUNET_free (pkey);
1788   }
1789   else
1790   {
1791     /* Name ends with ".gnu", eat ".gnu" and continue with resolution */
1792     GNUNET_free (resolver_lookup_get_next_label (rh));
1793   }
1794   ac = GNUNET_new (struct AuthorityChain);
1795   ac->rh = rh;
1796   ac->label = resolver_lookup_get_next_label (rh);
1797   if (NULL == ac->label)
1798     /* name was just "gnu", so we default to label '+' */
1799     ac->label = GNUNET_strdup (GNUNET_GNS_MASTERZONE_STR);
1800   ac->gns_authority = GNUNET_YES;
1801   ac->authority_info.gns_authority = rh->authority_zone;
1802   GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1803                                     rh->ac_tail,
1804                                     ac);
1805   rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1806                                           rh);
1807 }
1808
1809
1810 /**
1811  * Lookup of a record in a specific zone calls lookup result processor
1812  * on result.
1813  *
1814  * @param zone the zone to perform the lookup in
1815  * @param record_type the record type to look up
1816  * @param name the name to look up
1817  * @param shorten_key a private key for use with PSEU import (can be NULL)
1818  * @param only_cached #GNUNET_NO to only check locally not DHT for performance
1819  * @param proc the processor to call on result
1820  * @param proc_cls the closure to pass to @a proc
1821  * @return handle to cancel operation
1822  */
1823 struct GNS_ResolverHandle *
1824 GNS_resolver_lookup (const struct GNUNET_CRYPTO_EccPublicKey *zone,
1825                      uint32_t record_type,
1826                      const char *name,
1827                      const struct GNUNET_CRYPTO_EccPrivateKey *shorten_key,
1828                      int only_cached,
1829                      GNS_ResultProcessor proc, void *proc_cls)
1830 {
1831   struct GNS_ResolverHandle *rh;
1832
1833   rh = GNUNET_new (struct GNS_ResolverHandle);
1834   GNUNET_CONTAINER_DLL_insert (rlh_head,
1835                                rlh_tail,
1836                                rh);
1837   rh->authority_zone = *zone;
1838   rh->proc = proc;
1839   rh->proc_cls = proc_cls;
1840   rh->only_cached = only_cached;
1841   rh->record_type = record_type;
1842   rh->name = GNUNET_strdup (name);
1843   rh->name_resolution_pos = strlen (name);
1844   if (NULL != shorten_key)
1845   {
1846     rh->shorten_key = GNUNET_new (struct GNUNET_CRYPTO_EccPrivateKey);
1847     *rh->shorten_key = *shorten_key;
1848   }
1849   start_resolver_lookup (rh);
1850   return rh;
1851 }
1852
1853
1854 /**
1855  * Cancel active resolution (i.e. client disconnected).
1856  *
1857  * @param rh resolution to abort
1858  */
1859 void
1860 GNS_resolver_lookup_cancel (struct GNS_ResolverHandle *rh)
1861 {
1862   struct DnsResult *dr;
1863   struct AuthorityChain *ac;
1864   struct VpnContext *vpn_ctx;
1865
1866   GNUNET_CONTAINER_DLL_remove (rlh_head,
1867                                rlh_tail,
1868                                rh);
1869   while (NULL != (ac = rh->ac_head))
1870   {
1871     GNUNET_CONTAINER_DLL_remove (rh->ac_head,
1872                                  rh->ac_tail,
1873                                  ac);
1874     GNUNET_free (ac->label);
1875     GNUNET_free (ac);
1876   }
1877   if (GNUNET_SCHEDULER_NO_TASK != rh->task_id)
1878   {
1879     GNUNET_SCHEDULER_cancel (rh->task_id);
1880     rh->task_id = GNUNET_SCHEDULER_NO_TASK;
1881   }
1882   if (NULL != rh->get_handle)
1883   {
1884     GNUNET_DHT_get_stop (rh->get_handle);
1885     rh->get_handle = NULL;
1886   }
1887   if (NULL != rh->dht_heap_node)
1888   {
1889     GNUNET_CONTAINER_heap_remove_node (rh->dht_heap_node);
1890     rh->dht_heap_node = NULL;
1891   }
1892   if (NULL != (vpn_ctx = rh->vpn_ctx))
1893   {
1894     GNUNET_VPN_cancel_request (vpn_ctx->vpn_request);
1895     GNUNET_free (vpn_ctx->rd_data);
1896     GNUNET_free (vpn_ctx);
1897   }
1898   if (NULL != rh->dns_request)
1899   {
1900     GNUNET_DNSSTUB_resolve_cancel (rh->dns_request);
1901     rh->dns_request = NULL;
1902   }
1903   if (NULL != rh->namestore_qe)
1904   {
1905     GNUNET_NAMESTORE_cancel (rh->namestore_qe);
1906     rh->namestore_qe = NULL;
1907   }
1908   if (NULL != rh->std_resolve)
1909   {
1910     GNUNET_RESOLVER_request_cancel (rh->std_resolve);
1911     rh->std_resolve = NULL;
1912   }
1913   while (NULL != (dr = rh->dns_result_head))
1914   {
1915     GNUNET_CONTAINER_DLL_remove (rh->dns_result_head,
1916                                  rh->dns_result_tail,
1917                                  dr);
1918     GNUNET_free (dr);
1919   }
1920   GNUNET_free_non_null (rh->shorten_key);
1921   GNUNET_free (rh->name);
1922   GNUNET_free (rh);
1923 }
1924
1925
1926 /* ***************** Resolver initialization ********************* */
1927
1928
1929 /**
1930  * Initialize the resolver
1931  *
1932  * @param nh the namestore handle
1933  * @param dht the dht handle
1934  * @param c configuration handle
1935  * @param max_bg_queries maximum number of parallel background queries in dht
1936  */
1937 void
1938 GNS_resolver_init (struct GNUNET_NAMESTORE_Handle *nh,
1939                    struct GNUNET_DHT_Handle *dht,
1940                    const struct GNUNET_CONFIGURATION_Handle *c,
1941                    unsigned long long max_bg_queries)
1942 {
1943   char *dns_ip;
1944
1945   cfg = c;
1946   namestore_handle = nh;
1947   dht_handle = dht;
1948   dht_lookup_heap =
1949     GNUNET_CONTAINER_heap_create (GNUNET_CONTAINER_HEAP_ORDER_MIN);
1950   max_allowed_background_queries = max_bg_queries;
1951   if (GNUNET_OK !=
1952       GNUNET_CONFIGURATION_get_value_string (c,
1953                                              "gns",
1954                                              "DNS_RESOLVER",
1955                                              &dns_ip))
1956   {
1957     /* user did not specify DNS resolver, use 8.8.8.8 */
1958     dns_ip = GNUNET_strdup ("8.8.8.8");
1959   }
1960   dns_handle = GNUNET_DNSSTUB_start (dns_ip);
1961   GNUNET_free (dns_ip);
1962   vpn_handle = GNUNET_VPN_connect (cfg);
1963 }
1964
1965
1966 /**
1967  * Shutdown resolver
1968  */
1969 void
1970 GNS_resolver_done ()
1971 {
1972   struct GNS_ResolverHandle *rh;
1973
1974   /* abort active resolutions */
1975   while (NULL != (rh = rlh_head))
1976   {
1977     rh->proc (rh->proc_cls, 0, NULL);
1978     GNS_resolver_lookup_cancel (rh);
1979   }
1980   GNUNET_CONTAINER_heap_destroy (dht_lookup_heap);
1981   dht_lookup_heap = NULL;
1982   GNUNET_DNSSTUB_stop (dns_handle);
1983   dns_handle = NULL;
1984   GNUNET_VPN_disconnect (vpn_handle);
1985   vpn_handle = NULL;
1986   dht_handle = NULL;
1987   namestore_handle = NULL;
1988 }
1989
1990
1991 /* *************** common helper functions (do not really belong here) *********** */
1992
1993 /**
1994  * Checks if @a name ends in ".TLD"
1995  *
1996  * @param name the name to check
1997  * @param tld the TLD to check for
1998  * @return GNUNET_YES or GNUNET_NO
1999  */
2000 int
2001 is_tld (const char* name, const char* tld)
2002 {
2003   size_t offset = 0;
2004
2005   if (strlen (name) <= strlen (tld))
2006     return GNUNET_NO;
2007   offset = strlen (name) - strlen (tld);
2008   if (0 != strcmp (name + offset, tld))
2009     return GNUNET_NO;
2010   return GNUNET_YES;
2011 }
2012
2013
2014 /* end of gnunet-service-gns_resolver.c */