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 REVOCATION service!), (#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_gnsrecord_lib.h"
  38 #include "gnunet_namecache_service.h"
  39 #include "gnunet_namestore_service.h"
  40 #include "gnunet_dns_service.h"
  41 #include "gnunet_resolver_service.h"
  42 #include "gnunet_revocation_service.h"
  43 #include "gnunet_dnsparser_lib.h"
  44 #include "gnunet_gns_service.h"
  45 #include "gns.h"
  46 #include "gnunet-service-gns_resolver.h"
  47 #include "gnunet-service-gns_shorten.h"
  48 #include "gnunet_vpn_service.h"
  49
  50
  51 /**
  52  * Default DHT timeout for lookups.
  53  */
  54 #define DHT_LOOKUP_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 60)
  55
  56 /**
  57  * Default timeout for DNS lookups.
  58  */
  59 #define DNS_LOOKUP_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)
  60
  61 /**
  62  * Default timeout for VPN redirections.
  63  */
  64 #define VPN_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 30)
  65
  66 /**
  67  * DHT replication level
  68  */
  69 #define DHT_GNS_REPLICATION_LEVEL 5
  70
  71 /**
  72  * How deep do we allow recursions to go before we abort?
  73  */
  74 #define MAX_RECURSION 256
  75
  76
  77 /**
  78  * DLL to hold the authority chain we had to pass in the resolution
  79  * process.
  80  */
  81 struct AuthorityChain
  82 {
  83   /**
  84    * This is a DLL.
  85    */
  86   struct AuthorityChain *prev;
  87
  88   /**
  89    * This is a DLL.
  90    */
  91   struct AuthorityChain *next;
  92
  93   /**
  94    * Resolver handle this entry in the chain belongs to.
  95    */
  96   struct GNS_ResolverHandle *rh;
  97
  98   /**
  99    * label/name corresponding to the authority
 100    */
 101   char *label;
 102
 103   /**
 104    * #GNUNET_YES if the authority was a GNS authority,
 105    * #GNUNET_NO if the authority was a DNS authority.
 106    */
 107   int gns_authority;
 108
 109   /**
 110    * Information about the resolver authority for this label.
 111    */
 112   union
 113   {
 114
 115     /**
 116      * The zone of the GNS authority
 117      */
 118     struct GNUNET_CRYPTO_EcdsaPublicKey gns_authority;
 119
 120     struct
 121     {
 122       /**
 123        * Domain of the DNS resolver that is the authority.
 124        * (appended to construct the DNS name to resolve;
 125        * this is NOT the DNS name of the DNS server!).
 126        */
 127       char name[GNUNET_DNSPARSER_MAX_NAME_LENGTH + 1];
 128
 129       /**
 130        * IP address of the DNS resolver that is authoritative.
 131        * (this implementation currently only supports one
 132        * IP at a time).
 133        */
 134       struct sockaddr_storage dns_ip;
 135
 136     } dns_authority;
 137
 138   } authority_info;
 139
 140 };
 141
 142
 143 /**
 144  * A result we got from DNS.
 145  */
 146 struct DnsResult
 147 {
 148
 149   /**
 150    * Kept in DLL.
 151    */
 152   struct DnsResult *next;
 153
 154   /**
 155    * Kept in DLL.
 156    */
 157   struct DnsResult *prev;
 158
 159   /**
 160    * Binary value stored in the DNS record (appended to this struct)
 161    */
 162   const void *data;
 163
 164   /**
 165    * Expiration time for the DNS record, 0 if we didn't
 166    * get anything useful (i.e. 'gethostbyname' was used).
 167    */
 168   uint64_t expiration_time;
 169
 170   /**
 171    * Number of bytes in @e data.
 172    */
 173   size_t data_size;
 174
 175   /**
 176    * Type of the GNS/DNS record.
 177    */
 178   uint32_t record_type;
 179
 180 };
 181
 182
 183 /**
 184  * Closure for #vpn_allocation_cb.
 185  */
 186 struct VpnContext
 187 {
 188
 189   /**
 190    * Which resolution process are we processing.
 191    */
 192   struct GNS_ResolverHandle *rh;
 193
 194   /**
 195    * Handle to the VPN request that we were performing.
 196    */
 197   struct GNUNET_VPN_RedirectionRequest *vpn_request;
 198
 199   /**
 200    * Number of records serialized in @e rd_data.
 201    */
 202   unsigned int rd_count;
 203
 204   /**
 205    * Serialized records.
 206    */
 207   char *rd_data;
 208
 209   /**
 210    * Number of bytes in @e rd_data.
 211    */
 212   size_t rd_data_size;
 213 };
 214
 215
 216 /**
 217  * Information we keep during the resolution of an
 218  * IP address for a DNS server while handling a
 219  * GNS2DNS record.
 220  */
 221 struct Gns2DnsContext
 222 {
 223
 224   /**
 225    * DNS domain in which the resolution will continue
 226    * (first part of the GNS2DNS record).
 227    */
 228   char *ns;
 229
 230   /**
 231    * Handle for the resolution of the IP part of the
 232    * GNS2DNS record.  Will return to us the addresses
 233    * of the DNS resolver to use.
 234    */
 235   struct GNS_ResolverHandle *rh;
 236
 237 };
 238
 239
 240 /**
 241  * Handle to a currenty pending resolution.  On result (positive or
 242  * negative) the #GNS_ResultProcessor is called.
 243  */
 244 struct GNS_ResolverHandle
 245 {
 246
 247   /**
 248    * DLL
 249    */
 250   struct GNS_ResolverHandle *next;
 251
 252   /**
 253    * DLL
 254    */
 255   struct GNS_ResolverHandle *prev;
 256
 257   /**
 258    * The top-level GNS authoritative zone to query
 259    */
 260   struct GNUNET_CRYPTO_EcdsaPublicKey authority_zone;
 261
 262   /**
 263    * called when resolution phase finishes
 264    */
 265   GNS_ResultProcessor proc;
 266
 267   /**
 268    * closure passed to @e proc
 269    */
 270   void* proc_cls;
 271
 272   /**
 273    * Handle used during GNS2DNS resolution for looking up the
 274    * IP address of the DNS server.
 275    */
 276   struct Gns2DnsContext *g2dc;
 277
 278   /**
 279    * Handle for DHT lookups. should be NULL if no lookups are in progress
 280    */
 281   struct GNUNET_DHT_GetHandle *get_handle;
 282
 283   /**
 284    * Handle to a VPN request, NULL if none is active.
 285    */
 286   struct VpnContext *vpn_ctx;
 287
 288   /**
 289    * Socket for a DNS request, NULL if none is active.
 290    */
 291   struct GNUNET_DNSSTUB_RequestSocket *dns_request;
 292
 293   /**
 294    * Handle for standard DNS resolution, NULL if none is active.
 295    */
 296   struct GNUNET_RESOLVER_RequestHandle *std_resolve;
 297
 298   /**
 299    * Pending Namecache lookup task
 300    */
 301   struct GNUNET_NAMECACHE_QueueEntry *namecache_qe;
 302
 303   /**
 304    * Pending revocation check.
 305    */
 306   struct GNUNET_REVOCATION_Query *rev_check;
 307
 308   /**
 309    * Heap node associated with this lookup.  Used to limit number of
 310    * concurrent requests.
 311    */
 312   struct GNUNET_CONTAINER_HeapNode *dht_heap_node;
 313
 314   /**
 315    * DLL to store the authority chain
 316    */
 317   struct AuthorityChain *ac_head;
 318
 319   /**
 320    * DLL to store the authority chain
 321    */
 322   struct AuthorityChain *ac_tail;
 323
 324   /**
 325    * Private key of the shorten zone, NULL to not shorten.
 326    */
 327   struct GNUNET_CRYPTO_EcdsaPrivateKey *shorten_key;
 328
 329   /**
 330    * ID of a task associated with the resolution process.
 331    */
 332   GNUNET_SCHEDULER_TaskIdentifier task_id;
 333
 334   /**
 335    * The name to resolve
 336    */
 337   char *name;
 338
 339   /**
 340    * DLL of results we got from DNS.
 341    */
 342   struct DnsResult *dns_result_head;
 343
 344   /**
 345    * DLL of results we got from DNS.
 346    */
 347   struct DnsResult *dns_result_tail;
 348
 349   /**
 350    * Current offset in 'name' where we are resolving.
 351    */
 352   size_t name_resolution_pos;
 353
 354   /**
 355    * Use only cache
 356    */
 357   int only_cached;
 358
 359   /**
 360    * Desired type for the resolution.
 361    */
 362   int record_type;
 363
 364   /**
 365    * We increment the loop limiter for each step in a recursive
 366    * resolution.  If it passes our threshold (i.e. due to
 367    * self-recursion in the resolution, i.e CNAME fun), we stop.
 368    */
 369   unsigned int loop_limiter;
 370
 371 };
 372
 373
 374 /**
 375  * Active namestore caching operations.
 376  */
 377 struct CacheOps
 378 {
 379
 380   /**
 381    * Organized in a DLL.
 382    */
 383   struct CacheOps *next;
 384
 385   /**
 386    * Organized in a DLL.
 387    */
 388   struct CacheOps *prev;
 389
 390   /**
 391    * Pending Namestore caching task.
 392    */
 393   struct GNUNET_NAMECACHE_QueueEntry *namecache_qe_cache;
 394
 395 };
 396
 397
 398 /**
 399  * Our handle to the namecache service
 400  */
 401 static struct GNUNET_NAMECACHE_Handle *namecache_handle;
 402
 403 /**
 404  * Our handle to the vpn service
 405  */
 406 static struct GNUNET_VPN_Handle *vpn_handle;
 407
 408 /**
 409  * Resolver handle to the dht
 410  */
 411 static struct GNUNET_DHT_Handle *dht_handle;
 412
 413 /**
 414  * Handle to perform DNS lookups.
 415  */
 416 static struct GNUNET_DNSSTUB_Context *dns_handle;
 417
 418 /**
 419  * Heap for limiting parallel DHT lookups
 420  */
 421 static struct GNUNET_CONTAINER_Heap *dht_lookup_heap;
 422
 423 /**
 424  * Maximum amount of parallel queries to the DHT
 425  */
 426 static unsigned long long max_allowed_background_queries;
 427
 428 /**
 429  * Head of resolver lookup list
 430  */
 431 static struct GNS_ResolverHandle *rlh_head;
 432
 433 /**
 434  * Tail of resolver lookup list
 435  */
 436 static struct GNS_ResolverHandle *rlh_tail;
 437
 438 /**
 439  * Organized in a DLL.
 440  */
 441 static struct CacheOps *co_head;
 442
 443 /**
 444  * Organized in a DLL.
 445  */
 446 static struct CacheOps *co_tail;
 447
 448
 449 /**
 450  * Global configuration.
 451  */
 452 static const struct GNUNET_CONFIGURATION_Handle *cfg;
 453
 454 #if 0
 455 /**
 456  * Check if name is in srv format (_x._y.xxx)
 457  *
 458  * @param name
 459  * @return #GNUNET_YES if true
 460  */
 461 static int
 462 is_srv (const char *name)
 463 {
 464   char *ndup;
 465   int ret;
 466
 467   if (*name != '_')
 468     return GNUNET_NO;
 469   if (NULL == strstr (name, "._"))
 470     return GNUNET_NO;
 471   ret = GNUNET_YES;
 472   ndup = GNUNET_strdup (name);
 473   strtok (ndup, ".");
 474   if (NULL == strtok (NULL, "."))
 475     ret = GNUNET_NO;
 476   if (NULL == strtok (NULL, "."))
 477     ret = GNUNET_NO;
 478   if (NULL != strtok (NULL, "."))
 479     ret = GNUNET_NO;
 480   GNUNET_free (ndup);
 481   return ret;
 482 }
 483 #endif
 484
 485
 486 /**
 487  * Determine if this name is canonical (is a legal name in a zone, without delegation);
 488  * note that we do not test that the name does not contain illegal characters, we only
 489  * test for delegation.  Note that service records (i.e. _foo._srv) are canonical names
 490  * even though they consist of multiple labels.
 491  *
 492  * Examples:
 493  * a.b.gnu  = not canonical
 494  * a         = canonical
 495  * _foo._srv = canonical
 496  * _f.bar    = not canonical
 497  *
 498  * @param name the name to test
 499  * @return #GNUNET_YES if canonical
 500  */
 501 static int
 502 is_canonical (const char *name)
 503 {
 504   const char *pos;
 505   const char *dot;
 506
 507   if (NULL == strchr (name, '.'))
 508     return GNUNET_YES;
 509   if ('_' != name[0])
 510     return GNUNET_NO;
 511   pos = &name[1];
 512   while (NULL != (dot = strchr (pos, '.')))
 513     if ('_' != dot[1])
 514       return GNUNET_NO;
 515     else
 516       pos = dot + 1;
 517   return GNUNET_YES;
 518 }
 519
 520 /* ************************** Resolution **************************** */
 521
 522 /**
 523  * Expands a name ending in .+ with the zone of origin.
 524  *
 525  * @param rh resolution context
 526  * @param name name to modify (to be free'd or returned)
 527  * @return updated name
 528  */
 529 static char *
 530 translate_dot_plus (struct GNS_ResolverHandle *rh,
 531                     char *name)
 532 {
 533   char *ret;
 534   size_t s_len = strlen (name);
 535
 536   if (0 != strcmp (&name[s_len - 2],
 537                    ".+"))
 538     return name; /* did not end in ".+" */
 539   GNUNET_assert (GNUNET_YES == rh->ac_tail->gns_authority);
 540   GNUNET_asprintf (&ret,
 541                    "%.*s.%s",
 542                    (int) (s_len - 2),
 543                    name,
 544                    GNUNET_GNSRECORD_pkey_to_zkey (&rh->ac_tail->authority_info.gns_authority));
 545   GNUNET_free (name);
 546   return ret;
 547 }
 548
 549
 550 /**
 551  * Task scheduled to asynchronously fail a resolution.
 552  *
 553  * @param cls the 'struct GNS_ResolverHandle' of the resolution to fail
 554  * @param tc task context
 555  */
 556 static void
 557 fail_resolution (void *cls,
 558                  const struct GNUNET_SCHEDULER_TaskContext *tc)
 559 {
 560   struct GNS_ResolverHandle *rh = cls;
 561
 562   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
 563   rh->proc (rh->proc_cls, 0, NULL);
 564   GNS_resolver_lookup_cancel (rh);
 565 }
 566
 567
 568 #if (defined WINDOWS) || (defined DARWIN)
 569 /* Don't have this on W32, here's a naive implementation
 570  * Was somehow removed on OS X ...  */
 571 void *
 572 memrchr (const void *s,
 573          int c,
 574          size_t n)
 575 {
 576   const unsigned char *ucs = s;
 577   ssize_t i;
 578
 579   for (i = n - 1; i >= 0; i--)
 580     if (c == (int) ucs[i])
 581       return (void *) &ucs[i];
 582   return NULL;
 583 }
 584 #endif
 585
 586
 587 /**
 588  * Get the next, rightmost label from the name that we are trying to resolve,
 589  * and update the resolution position accordingly.
 590  *
 591  * @param rh handle to the resolution operation to get the next label from
 592  * @return NULL if there are no more labels
 593  */
 594 static char *
 595 resolver_lookup_get_next_label (struct GNS_ResolverHandle *rh)
 596 {
 597   const char *rp;
 598   const char *dot;
 599   size_t len;
 600
 601   if (0 == rh->name_resolution_pos)
 602     return NULL;
 603   dot = memrchr (rh->name, (int) '.', rh->name_resolution_pos);
 604   if (NULL == dot)
 605   {
 606     /* done, this was the last one */
 607     len = rh->name_resolution_pos;
 608     rp = rh->name;
 609     rh->name_resolution_pos = 0;
 610   }
 611   else
 612   {
 613     /* advance by one label */
 614     len = rh->name_resolution_pos - (dot - rh->name) - 1;
 615     rp = dot + 1;
 616     rh->name_resolution_pos = dot - rh->name;
 617   }
 618   return GNUNET_strndup (rp, len);
 619 }
 620
 621
 622 /**
 623  * Gives the cummulative result obtained to the callback and clean up the request.
 624  *
 625  * @param rh resolution process that has culminated in a result
 626  */
 627 static void
 628 transmit_lookup_dns_result (struct GNS_ResolverHandle *rh)
 629 {
 630   struct DnsResult *pos;
 631   unsigned int n;
 632   unsigned int i;
 633
 634   n = 0;
 635   for (pos = rh->dns_result_head; NULL != pos; pos = pos->next)
 636     n++;
 637   {
 638     struct GNUNET_GNSRECORD_Data rd[n];
 639
 640     i = 0;
 641     for (pos = rh->dns_result_head; NULL != pos; pos = pos->next)
 642     {
 643       rd[i].data = pos->data;
 644       rd[i].data_size = pos->data_size;
 645       rd[i].record_type = pos->record_type;
 646       if (0 == pos->expiration_time)
 647       {
 648         rd[i].flags = GNUNET_GNSRECORD_RF_RELATIVE_EXPIRATION;
 649         rd[i].expiration_time = 0;
 650       }
 651       else
 652       {
 653         rd[i].flags = GNUNET_GNSRECORD_RF_NONE;
 654         rd[i].expiration_time = pos->expiration_time;
 655       }
 656       i++;
 657     }
 658     GNUNET_assert (i == n);
 659     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 660                 "Transmitting standard DNS result with %u records\n",
 661                 n);
 662     rh->proc (rh->proc_cls,
 663               n,
 664               rd);
 665   }
 666   GNS_resolver_lookup_cancel (rh);
 667 }
 668
 669
 670 /**
 671  * Add a result from DNS to the records to be returned to the application.
 672  *
 673  * @param rh resolution request to extend with a result
 674  * @param expiration_time expiration time for the answer
 675  * @param record_type DNS record type of the answer
 676  * @param data_size number of bytes in @a data
 677  * @param data binary data to return in DNS record
 678  */
 679 static void
 680 add_dns_result (struct GNS_ResolverHandle *rh,
 681                 uint64_t expiration_time,
 682                 uint32_t record_type,
 683                 size_t data_size,
 684                 const void *data)
 685 {
 686   struct DnsResult *res;
 687
 688   res = GNUNET_malloc (sizeof (struct DnsResult) + data_size);
 689   res->expiration_time = expiration_time;
 690   res->data_size = data_size;
 691   res->record_type = record_type;
 692   res->data = &res[1];
 693   memcpy (&res[1], data, data_size);
 694   GNUNET_CONTAINER_DLL_insert (rh->dns_result_head,
 695                                rh->dns_result_tail,
 696                                res);
 697 }
 698
 699
 700 /**
 701  * We had to do a DNS lookup.  Convert the result (if any) and return
 702  * it.
 703  *
 704  * @param cls closure with the `struct GNS_ResolverHandle`
 705  * @param addr one of the addresses of the host, NULL for the last address
 706  * @param addrlen length of the address
 707  */
 708 static void
 709 handle_dns_result (void *cls,
 710                    const struct sockaddr *addr,
 711                    socklen_t addrlen)
 712 {
 713   struct GNS_ResolverHandle *rh = cls;
 714   const struct sockaddr_in *sa4;
 715   const struct sockaddr_in6 *sa6;
 716
 717   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 718               "Received %u bytes of DNS IP data\n",
 719               addrlen);
 720   if (NULL == addr)
 721   {
 722     rh->std_resolve = NULL;
 723     transmit_lookup_dns_result (rh);
 724     return;
 725   }
 726   switch (addr->sa_family)
 727   {
 728   case AF_INET:
 729     sa4 = (const struct sockaddr_in *) addr;
 730     add_dns_result (rh,
 731                     0 /* expiration time is unknown */,
 732                     GNUNET_DNSPARSER_TYPE_A,
 733                     sizeof (struct in_addr),
 734                     &sa4->sin_addr);
 735     break;
 736   case AF_INET6:
 737     sa6 = (const struct sockaddr_in6 *) addr;
 738     add_dns_result (rh,
 739                     0 /* expiration time is unknown */,
 740                     GNUNET_DNSPARSER_TYPE_AAAA,
 741                     sizeof (struct in6_addr),
 742                     &sa6->sin6_addr);
 743     break;
 744   default:
 745     GNUNET_break (0);
 746     break;
 747   }
 748 }
 749
 750
 751 /**
 752  * Task scheduled to continue with the resolution process.
 753  *
 754  * @param cls the 'struct GNS_ResolverHandle' of the resolution
 755  * @param tc task context
 756  */
 757 static void
 758 recursive_resolution (void *cls,
 759                       const struct GNUNET_SCHEDULER_TaskContext *tc);
 760
 761
 762 /**
 763  * Begin the resolution process from 'name', starting with
 764  * the identification of the zone specified by 'name'.
 765  *
 766  * @param rh resolution to perform
 767  */
 768 static void
 769 start_resolver_lookup (struct GNS_ResolverHandle *rh);
 770
 771
 772 /**
 773  * Function called with the result of a DNS resolution.
 774  *
 775  * @param cls the request handle of the resolution that
 776  *        we were attempting to make
 777  * @param rs socket that received the response
 778  * @param dns dns response, never NULL
 779  * @param dns_len number of bytes in @a dns
 780  */
 781 static void
 782 dns_result_parser (void *cls,
 783                    struct GNUNET_DNSSTUB_RequestSocket *rs,
 784                    const struct GNUNET_TUN_DnsHeader *dns,
 785                    size_t dns_len)
 786 {
 787   struct GNS_ResolverHandle *rh = cls;
 788   struct GNUNET_DNSPARSER_Packet *p;
 789   const struct GNUNET_DNSPARSER_Record *rec;
 790   unsigned int rd_count;
 791   unsigned int i;
 792
 793   rh->dns_request = NULL;
 794   GNUNET_SCHEDULER_cancel (rh->task_id);
 795   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
 796   p = GNUNET_DNSPARSER_parse ((const char *) dns,
 797                               dns_len);
 798   if (NULL == p)
 799   {
 800     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
 801                 _("Failed to parse DNS response\n"));
 802     rh->proc (rh->proc_cls, 0, NULL);
 803     GNS_resolver_lookup_cancel (rh);
 804     return;
 805   }
 806   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 807               "Received DNS response for `%s' with %u answers\n",
 808               rh->ac_tail->label,
 809               (unsigned int) p->num_answers);
 810   if ( (p->num_answers > 0) &&
 811        (GNUNET_DNSPARSER_TYPE_CNAME == p->answers[0].type) &&
 812        (GNUNET_DNSPARSER_TYPE_CNAME != rh->record_type) )
 813     {
 814       GNUNET_free (rh->name);
 815       rh->name = GNUNET_strdup (p->answers[0].data.hostname);
 816       start_resolver_lookup (rh);
 817       GNUNET_DNSPARSER_free_packet (p);
 818       return;
 819     }
 820   /* FIXME: add DNAME support */
 821
 822   /* convert from (parsed) DNS to (binary) GNS format! */
 823   rd_count = p->num_answers + p->num_authority_records + p->num_additional_records;
 824   {
 825     struct GNUNET_GNSRECORD_Data rd[rd_count];
 826     unsigned int skip;
 827     char buf[UINT16_MAX];
 828     size_t buf_off;
 829     size_t buf_start;
 830
 831     buf_off = 0;
 832     skip = 0;
 833     memset (rd, 0, sizeof (rd));
 834     for (i=0;i<rd_count;i++)
 835     {
 836       if (i < p->num_answers)
 837         rec = &p->answers[i];
 838       else if (i < p->num_answers + p->num_authority_records)
 839         rec = &p->authority_records[i - p->num_answers];
 840       else
 841         rec = &p->authority_records[i - p->num_answers - p->num_authority_records];
 842       /* As we copied the full DNS name to 'rh->ac_tail->label', this
 843          should be the correct check to see if this record is actually
 844          a record for our label... */
 845       if (0 != strcmp (rec->name,
 846                        rh->ac_tail->label))
 847       {
 848         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 849                     "Dropping record `%s', does not match desired name `%s'\n",
 850                     rec->name,
 851                     rh->ac_tail->label);
 852         skip++;
 853         continue;
 854       }
 855       rd[i - skip].record_type = rec->type;
 856       rd[i - skip].expiration_time = rec->expiration_time.abs_value_us;
 857       switch (rec->type)
 858       {
 859       case GNUNET_DNSPARSER_TYPE_A:
 860         if (rec->data.raw.data_len != sizeof (struct in_addr))
 861         {
 862           GNUNET_break_op (0);
 863           skip++;
 864           continue;
 865         }
 866         rd[i - skip].data_size = rec->data.raw.data_len;
 867         rd[i - skip].data = rec->data.raw.data;
 868         break;
 869       case GNUNET_DNSPARSER_TYPE_AAAA:
 870         if (rec->data.raw.data_len != sizeof (struct in6_addr))
 871         {
 872           GNUNET_break_op (0);
 873           skip++;
 874           continue;
 875         }
 876         rd[i - skip].data_size = rec->data.raw.data_len;
 877         rd[i - skip].data = rec->data.raw.data;
 878         break;
 879       case GNUNET_DNSPARSER_TYPE_CNAME:
 880       case GNUNET_DNSPARSER_TYPE_PTR:
 881       case GNUNET_DNSPARSER_TYPE_NS:
 882         buf_start = buf_off;
 883         if (GNUNET_OK !=
 884             GNUNET_DNSPARSER_builder_add_name (buf,
 885                                                sizeof (buf),
 886                                                &buf_off,
 887                                                rec->data.hostname))
 888         {
 889           GNUNET_break (0);
 890           skip++;
 891           continue;
 892         }
 893         rd[i - skip].data_size = buf_off - buf_start;
 894         rd[i - skip].data = &buf[buf_start];
 895         break;
 896       case GNUNET_DNSPARSER_TYPE_SOA:
 897         buf_start = buf_off;
 898         if (GNUNET_OK !=
 899             GNUNET_DNSPARSER_builder_add_soa (buf,
 900                                                sizeof (buf),
 901                                                &buf_off,
 902                                                rec->data.soa))
 903         {
 904           GNUNET_break (0);
 905           skip++;
 906           continue;
 907         }
 908         rd[i - skip].data_size = buf_off - buf_start;
 909         rd[i - skip].data = &buf[buf_start];
 910         break;
 911       case GNUNET_DNSPARSER_TYPE_MX:
 912         buf_start = buf_off;
 913         if (GNUNET_OK !=
 914             GNUNET_DNSPARSER_builder_add_mx (buf,
 915                                              sizeof (buf),
 916                                              &buf_off,
 917                                              rec->data.mx))
 918         {
 919           GNUNET_break (0);
 920           skip++;
 921           continue;
 922         }
 923         rd[i - skip].data_size = buf_off - buf_start;
 924         rd[i - skip].data = &buf[buf_start];
 925         break;
 926       case GNUNET_DNSPARSER_TYPE_SRV:
 927         buf_start = buf_off;
 928         if (GNUNET_OK !=
 929             GNUNET_DNSPARSER_builder_add_srv (buf,
 930                                               sizeof (buf),
 931                                               &buf_off,
 932                                               rec->data.srv))
 933         {
 934           GNUNET_break (0);
 935           skip++;
 936           continue;
 937         }
 938         rd[i - skip].data_size = buf_off - buf_start;
 939         rd[i - skip].data = &buf[buf_start];
 940         break;
 941       default:
 942         GNUNET_log (GNUNET_ERROR_TYPE_INFO,
 943                     _("Skipping record of unsupported type %d\n"),
 944                     rec->type);
 945         skip++;
 946         continue;
 947       }
 948     }
 949     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 950                 "Returning DNS response for `%s' with %u answers\n",
 951                 rh->ac_tail->label,
 952                 (unsigned int) p->num_answers);
 953     rh->proc (rh->proc_cls, rd_count - skip, rd);
 954     GNS_resolver_lookup_cancel (rh);
 955   }
 956   GNUNET_DNSPARSER_free_packet (p);
 957 }
 958
 959
 960 /**
 961  * Perform recursive DNS resolution.  Asks the given DNS resolver to
 962  * resolve "rh->dns_name", possibly recursively proceeding following
 963  * NS delegations, CNAMES, etc., until 'rh->loop_limiter' bounds us or
 964  * we find the answer.
 965  *
 966  * @param rh resolution information
 967  */
 968 static void
 969 recursive_dns_resolution (struct GNS_ResolverHandle *rh)
 970 {
 971   struct AuthorityChain *ac;
 972   socklen_t sa_len;
 973   struct GNUNET_DNSPARSER_Query *query;
 974   struct GNUNET_DNSPARSER_Packet *p;
 975   char *dns_request;
 976   size_t dns_request_length;
 977
 978   ac = rh->ac_tail;
 979   GNUNET_assert (NULL != ac);
 980   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 981               "Starting DNS lookup for `%s'\n",
 982               ac->label);
 983   GNUNET_assert (GNUNET_NO == ac->gns_authority);
 984   switch (((const struct sockaddr *) &ac->authority_info.dns_authority.dns_ip)->sa_family)
 985   {
 986   case AF_INET:
 987     sa_len = sizeof (struct sockaddr_in);
 988     break;
 989   case AF_INET6:
 990     sa_len = sizeof (struct sockaddr_in6);
 991     break;
 992   default:
 993     GNUNET_break (0);
 994     rh->proc (rh->proc_cls, 0, NULL);
 995     GNS_resolver_lookup_cancel (rh);
 996     return;
 997   }
 998   query = GNUNET_new (struct GNUNET_DNSPARSER_Query);
 999   query->name = GNUNET_strdup (ac->label);
1000   query->type = rh->record_type;
1001   query->dns_traffic_class = GNUNET_TUN_DNS_CLASS_INTERNET;
1002   p = GNUNET_new (struct GNUNET_DNSPARSER_Packet);
1003   p->queries = query;
1004   p->num_queries = 1;
1005   p->id = (uint16_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
1006                                                UINT16_MAX);
1007   p->flags.opcode = GNUNET_TUN_DNS_OPCODE_QUERY;
1008   p->flags.recursion_desired = 1;
1009   if (GNUNET_OK !=
1010       GNUNET_DNSPARSER_pack (p, 1024, &dns_request, &dns_request_length))
1011   {
1012     GNUNET_break (0);
1013     rh->proc (rh->proc_cls, 0, NULL);
1014     GNS_resolver_lookup_cancel (rh);
1015   }
1016   else
1017   {
1018     rh->dns_request = GNUNET_DNSSTUB_resolve (dns_handle,
1019                                               (const struct sockaddr *) &ac->authority_info.dns_authority.dns_ip,
1020                                               sa_len,
1021                                               dns_request,
1022                                               dns_request_length,
1023                                               &dns_result_parser,
1024                                               rh);
1025     rh->task_id = GNUNET_SCHEDULER_add_delayed (DNS_LOOKUP_TIMEOUT,
1026                                                 &fail_resolution,
1027                                                 rh);
1028   }
1029   GNUNET_free (dns_request);
1030   GNUNET_DNSPARSER_free_packet (p);
1031 }
1032
1033
1034 /**
1035  * We encountered a CNAME record during our resolution.
1036  * Merge it into our chain.
1037  *
1038  * @param rh resolution we are performing
1039  * @param cname value of the cname record we got for the current
1040  *        authority chain tail
1041  */
1042 static void
1043 handle_gns_cname_result (struct GNS_ResolverHandle *rh,
1044                          const char *cname)
1045 {
1046   size_t nlen;
1047   char *res;
1048   struct AuthorityChain *ac;
1049
1050   nlen = strlen (cname);
1051   if ( (nlen > 2) &&
1052        (0 == strcmp (".+",
1053                      &cname[nlen - 2])) )
1054   {
1055     /* CNAME resolution continues relative to current domain */
1056     if (0 == rh->name_resolution_pos)
1057     {
1058       res = GNUNET_strndup (cname, nlen - 2);
1059       rh->name_resolution_pos = nlen - 2;
1060     }
1061     else
1062     {
1063       GNUNET_asprintf (&res,
1064                        "%.*s.%.*s",
1065                        (int) rh->name_resolution_pos,
1066                        rh->name,
1067                        (int) (nlen - 2),
1068                        cname);
1069       rh->name_resolution_pos = strlen (res);
1070     }
1071     GNUNET_free (rh->name);
1072     rh->name = res;
1073     ac = GNUNET_new (struct AuthorityChain);
1074     ac->rh = rh;
1075     ac->gns_authority = GNUNET_YES;
1076     ac->authority_info.gns_authority = rh->ac_tail->authority_info.gns_authority;
1077     ac->label = resolver_lookup_get_next_label (rh);
1078     /* tigger shortening */
1079     if (NULL != rh->shorten_key)
1080       GNS_shorten_start (rh->ac_tail->label,
1081                          &ac->authority_info.gns_authority,
1082                          rh->shorten_key);
1083     /* add AC to tail */
1084     GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1085                                       rh->ac_tail,
1086                                       ac);
1087     rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1088                                             rh);
1089     return;
1090   }
1091   /* name is absolute, start from the beginning */
1092   GNUNET_free (rh->name);
1093   rh->name = GNUNET_strdup (cname);
1094   start_resolver_lookup (rh);
1095 }
1096
1097
1098 /**
1099  * Process a records that were decrypted from a block.
1100  *
1101  * @param cls closure with the 'struct GNS_ResolverHandle'
1102  * @param rd_count number of entries in @a rd array
1103  * @param rd array of records with data to store
1104  */
1105 static void
1106 handle_gns_resolution_result (void *cls,
1107                               unsigned int rd_count,
1108                               const struct GNUNET_GNSRECORD_Data *rd);
1109
1110
1111 /**
1112  * Callback invoked from the VPN service once a redirection is
1113  * available.  Provides the IP address that can now be used to
1114  * reach the requested destination.  Replaces the "VPN" record
1115  * with the respective A/AAAA record and continues processing.
1116  *
1117  * @param cls closure
1118  * @param af address family, AF_INET or AF_INET6; AF_UNSPEC on error;
1119  *                will match 'result_af' from the request
1120  * @param address IP address (struct in_addr or struct in_addr6, depending on 'af')
1121  *                that the VPN allocated for the redirection;
1122  *                traffic to this IP will now be redirected to the
1123  *                specified target peer; NULL on error
1124  */
1125 static void
1126 vpn_allocation_cb (void *cls,
1127                    int af,
1128                    const void *address)
1129 {
1130   struct VpnContext *vpn_ctx = cls;
1131   struct GNS_ResolverHandle *rh = vpn_ctx->rh;
1132   struct GNUNET_GNSRECORD_Data rd[vpn_ctx->rd_count];
1133   unsigned int i;
1134
1135   vpn_ctx->vpn_request = NULL;
1136   rh->vpn_ctx = NULL;
1137   GNUNET_assert (GNUNET_OK ==
1138                  GNUNET_GNSRECORD_records_deserialize (vpn_ctx->rd_data_size,
1139                                                        vpn_ctx->rd_data,
1140                                                        vpn_ctx->rd_count,
1141                                                        rd));
1142   for (i=0;i<vpn_ctx->rd_count;i++)
1143   {
1144     if (GNUNET_GNSRECORD_TYPE_VPN == rd[i].record_type)
1145     {
1146       switch (af)
1147       {
1148       case AF_INET:
1149         rd[i].record_type = GNUNET_DNSPARSER_TYPE_A;
1150         rd[i].data_size = sizeof (struct in_addr);
1151         rd[i].expiration_time = GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT).abs_value_us;
1152         rd[i].flags = 0;
1153         rd[i].data = address;
1154         break;
1155       case AF_INET6:
1156         rd[i].record_type = GNUNET_DNSPARSER_TYPE_AAAA;
1157         rd[i].expiration_time = GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT).abs_value_us;
1158         rd[i].flags = 0;
1159         rd[i].data = address;
1160         rd[i].data_size = sizeof (struct in6_addr);
1161         break;
1162       default:
1163         GNUNET_assert (0);
1164       }
1165       break;
1166     }
1167   }
1168   GNUNET_assert (i < vpn_ctx->rd_count);
1169   handle_gns_resolution_result (rh,
1170                                 vpn_ctx->rd_count,
1171                                 rd);
1172   GNUNET_free (vpn_ctx->rd_data);
1173   GNUNET_free (vpn_ctx);
1174 }
1175
1176
1177 /**
1178  * We've resolved the IP address for the DNS resolver to use
1179  * after encountering a GNS2DNS record.
1180  *
1181  * TODO: Right now we only foward the request to ONE DNS resolver,
1182  * even if we get multiple IP addresses back; a correct implementation
1183  * should try all DNS resolvers.
1184  *
1185  * @param cls the `struct GNS_ResolverHandle` where we encountered
1186  *            the GNS2DNS record
1187  * @param rd_count number of records in @a rd
1188  * @param rd addresses for the DNS resolver  (presumably)
1189  */
1190 static void
1191 handle_gns2dns_result (void *cls,
1192                        unsigned int rd_count,
1193                        const struct GNUNET_GNSRECORD_Data *rd)
1194 {
1195   struct GNS_ResolverHandle *rh = cls;
1196   struct AuthorityChain *ac;
1197   unsigned int j;
1198   struct sockaddr *sa;
1199   struct sockaddr_in v4;
1200   struct sockaddr_in6 v6;
1201   size_t sa_len;
1202
1203   /* find suitable A/AAAA record */
1204   rh->g2dc->rh = NULL;
1205   sa = NULL;
1206   sa_len = 0;
1207   for (j=0;j<rd_count;j++)
1208   {
1209     switch (rd[j].record_type)
1210     {
1211     case GNUNET_DNSPARSER_TYPE_A:
1212       if (sizeof (struct in_addr) != rd[j].data_size)
1213       {
1214         GNUNET_break_op (0);
1215         rh->proc (rh->proc_cls, 0, NULL);
1216         GNS_resolver_lookup_cancel (rh);
1217         return;
1218       }
1219       /* FIXME: might want to check if we support IPv4 here,
1220          and otherwise skip this one and hope we find another */
1221       memset (&v4, 0, sizeof (v4));
1222       sa_len = sizeof (v4);
1223       v4.sin_family = AF_INET;
1224       v4.sin_port = htons (53);
1225 #if HAVE_SOCKADDR_IN_SIN_LEN
1226       v4.sin_len = (u_char) sa_len;
1227 #endif
1228       memcpy (&v4.sin_addr,
1229               rd[j].data,
1230               sizeof (struct in_addr));
1231       sa = (struct sockaddr *) &v4;
1232       break;
1233     case GNUNET_DNSPARSER_TYPE_AAAA:
1234       if (sizeof (struct in6_addr) != rd[j].data_size)
1235       {
1236         GNUNET_break_op (0);
1237         rh->proc (rh->proc_cls, 0, NULL);
1238         GNS_resolver_lookup_cancel (rh);
1239         return;
1240       }
1241       /* FIXME: might want to check if we support IPv6 here,
1242          and otherwise skip this one and hope we find another */
1243       memset (&v6, 0, sizeof (v6));
1244       sa_len = sizeof (v6);
1245       v6.sin6_family = AF_INET6;
1246       v6.sin6_port = htons (53);
1247 #if HAVE_SOCKADDR_IN_SIN_LEN
1248       v6.sin6_len = (u_char) sa_len;
1249 #endif
1250       memcpy (&v6.sin6_addr,
1251               rd[j].data,
1252               sizeof (struct in6_addr));
1253       sa = (struct sockaddr *) &v6;
1254       break;
1255     default:
1256       break;
1257     }
1258     if (NULL != sa)
1259       break;
1260   }
1261   if (NULL == sa)
1262   {
1263     /* we cannot continue; NS without A/AAAA */
1264     rh->proc (rh->proc_cls, 0, NULL);
1265     GNS_resolver_lookup_cancel (rh);
1266     return;
1267   }
1268   /* expand authority chain */
1269   ac = GNUNET_new (struct AuthorityChain);
1270   ac->rh = rh;
1271   strcpy (ac->authority_info.dns_authority.name,
1272           rh->g2dc->ns);
1273   memcpy (&ac->authority_info.dns_authority.dns_ip,
1274           sa,
1275           sa_len);
1276   /* for DNS recursion, the label is the full DNS name,
1277      created from the remainder of the GNS name and the
1278      name in the NS record */
1279   GNUNET_asprintf (&ac->label,
1280                    "%.*s%s%s",
1281                    (int) rh->name_resolution_pos,
1282                    rh->name,
1283                    (0 != rh->name_resolution_pos) ? "." : "",
1284                    rh->g2dc->ns);
1285   GNUNET_free (rh->g2dc->ns);
1286   GNUNET_free (rh->g2dc);
1287   rh->g2dc = NULL;
1288   GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1289                                     rh->ac_tail,
1290                                     ac);
1291   if (strlen (ac->label) > GNUNET_DNSPARSER_MAX_NAME_LENGTH)
1292   {
1293     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1294                 _("GNS lookup resulted in DNS name that is too long (`%s')\n"),
1295                 ac->label);
1296     rh->proc (rh->proc_cls, 0, NULL);
1297     GNS_resolver_lookup_cancel (rh);
1298     return;
1299   }
1300   /* recurse */
1301   rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1302                                           rh);
1303 }
1304
1305
1306 /**
1307  * Process a records that were decrypted from a block.
1308  *
1309  * @param cls closure with the `struct GNS_ResolverHandle`
1310  * @param rd_count number of entries in @a rd array
1311  * @param rd array of records with data to store
1312  */
1313 static void
1314 handle_gns_resolution_result (void *cls,
1315                               unsigned int rd_count,
1316                               const struct GNUNET_GNSRECORD_Data *rd)
1317 {
1318   struct GNS_ResolverHandle *rh = cls;
1319   struct AuthorityChain *ac;
1320   unsigned int i;
1321   char *cname;
1322   struct VpnContext *vpn_ctx;
1323   const struct GNUNET_TUN_GnsVpnRecord *vpn;
1324   const char *vname;
1325   struct GNUNET_HashCode vhash;
1326   int af;
1327   char scratch[UINT16_MAX];
1328   size_t scratch_off;
1329   size_t scratch_start;
1330   size_t off;
1331   struct GNUNET_GNSRECORD_Data rd_new[rd_count];
1332   unsigned int rd_off;
1333
1334   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1335               "Resolution succeeded for `%s' in zone %s, got %u records\n",
1336               rh->ac_tail->label,
1337               GNUNET_GNSRECORD_z2s (&rh->ac_tail->authority_info.gns_authority),
1338               rd_count);
1339   if (0 == rh->name_resolution_pos)
1340   {
1341     /* top-level match, are we done yet? */
1342     if ( (rd_count > 0) &&
1343          (GNUNET_DNSPARSER_TYPE_CNAME == rd[0].record_type) &&
1344          (GNUNET_DNSPARSER_TYPE_CNAME != rh->record_type) )
1345     {
1346       off = 0;
1347       cname = GNUNET_DNSPARSER_parse_name (rd[0].data,
1348                                            rd[0].data_size,
1349                                            &off);
1350       if ( (NULL == cname) ||
1351            (off != rd[0].data_size) )
1352       {
1353         GNUNET_break_op (0);
1354         rh->proc (rh->proc_cls, 0, NULL);
1355         GNS_resolver_lookup_cancel (rh);
1356         GNUNET_free_non_null (cname);
1357         return;
1358       }
1359       handle_gns_cname_result (rh,
1360                                cname);
1361       GNUNET_free (cname);
1362       return;
1363     }
1364     /* If A/AAAA was requested, but we got a VPN
1365        record, we convert it to A/AAAA using GNUnet VPN */
1366     if ( (GNUNET_DNSPARSER_TYPE_A == rh->record_type) ||
1367          (GNUNET_DNSPARSER_TYPE_AAAA == rh->record_type) )
1368     {
1369       for (i=0;i<rd_count;i++)
1370       {
1371         switch (rd[i].record_type)
1372         {
1373         case GNUNET_GNSRECORD_TYPE_VPN:
1374           {
1375             af = (GNUNET_DNSPARSER_TYPE_A == rh->record_type) ? AF_INET : AF_INET6;
1376             if (sizeof (struct GNUNET_TUN_GnsVpnRecord) <
1377                 rd[i].data_size)
1378             {
1379               GNUNET_break_op (0);
1380               rh->proc (rh->proc_cls, 0, NULL);
1381               GNS_resolver_lookup_cancel (rh);
1382               return;
1383             }
1384             vpn = (const struct GNUNET_TUN_GnsVpnRecord *) rd[i].data;
1385             vname = (const char *) &vpn[1];
1386             if ('\0' != vname[rd[i].data_size - 1 - sizeof (struct GNUNET_TUN_GnsVpnRecord)])
1387             {
1388               GNUNET_break_op (0);
1389               rh->proc (rh->proc_cls, 0, NULL);
1390               GNS_resolver_lookup_cancel (rh);
1391               return;
1392             }
1393             GNUNET_CRYPTO_hash (vname,
1394                                 strlen (vname), // FIXME: +1?
1395                                 &vhash);
1396             vpn_ctx = GNUNET_new (struct VpnContext);
1397             rh->vpn_ctx = vpn_ctx;
1398             vpn_ctx->rh = rh;
1399             vpn_ctx->rd_data_size = GNUNET_GNSRECORD_records_get_size (rd_count,
1400                                                                        rd);
1401             vpn_ctx->rd_data = GNUNET_malloc (vpn_ctx->rd_data_size);
1402             (void) GNUNET_GNSRECORD_records_serialize (rd_count,
1403                                                        rd,
1404                                                        vpn_ctx->rd_data_size,
1405                                                        vpn_ctx->rd_data);
1406             vpn_ctx->vpn_request = GNUNET_VPN_redirect_to_peer (vpn_handle,
1407                                                                 af,
1408                                                                 ntohs (vpn->proto),
1409                                                                 &vpn->peer,
1410                                                                 &vhash,
1411                                                                 GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT),
1412                                                                 &vpn_allocation_cb,
1413                                                                 rh);
1414             return;
1415           }
1416         case GNUNET_GNSRECORD_TYPE_GNS2DNS:
1417           {
1418             /* delegation to DNS */
1419             GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1420                         "Found GNS2DNS record, delegating to DNS!\n");
1421             goto do_recurse;
1422           }
1423         default:
1424           break;
1425         }
1426       }
1427     }
1428     /* convert relative names in record values to absolute names,
1429        using 'scratch' array for memory allocations */
1430     scratch_off = 0;
1431     rd_off = 0;
1432     for (i=0;i<rd_count;i++)
1433     {
1434       rd_new[rd_off] = rd[i];
1435       /* Check if the embedded name(s) end in "+", and if so,
1436          replace the "+" with the zone at "ac_tail", changing the name
1437          to a ".zkey".  The name is allocated on the 'scratch' array,
1438          so we can free it afterwards. */
1439       switch (rd[i].record_type)
1440       {
1441       case GNUNET_DNSPARSER_TYPE_CNAME:
1442         {
1443           char *cname;
1444
1445           off = 0;
1446           cname = GNUNET_DNSPARSER_parse_name (rd[i].data,
1447                                                rd[i].data_size,
1448                                                &off);
1449           if ( (NULL == cname) ||
1450                (off != rd[i].data_size) )
1451           {
1452             GNUNET_break_op (0); /* record not well-formed */
1453           }
1454           else
1455           {
1456             cname = translate_dot_plus (rh, cname);
1457             GNUNET_break (NULL != cname);
1458             scratch_start = scratch_off;
1459             if (GNUNET_OK !=
1460                 GNUNET_DNSPARSER_builder_add_name (scratch,
1461                                                    sizeof (scratch),
1462                                                    &scratch_off,
1463                                                    cname))
1464             {
1465               GNUNET_break (0);
1466             }
1467             else
1468             {
1469               rd_new[rd_off].data = &scratch[scratch_start];
1470               rd_new[rd_off].data_size = scratch_off - scratch_start;
1471               rd_off++;
1472             }
1473           }
1474           GNUNET_free_non_null (cname);
1475         }
1476         break;
1477       case GNUNET_DNSPARSER_TYPE_SOA:
1478         {
1479           struct GNUNET_DNSPARSER_SoaRecord *soa;
1480
1481           off = 0;
1482           soa = GNUNET_DNSPARSER_parse_soa (rd[i].data,
1483                                             rd[i].data_size,
1484                                             &off);
1485           if ( (NULL == soa) ||
1486                (off != rd[i].data_size) )
1487           {
1488             GNUNET_break_op (0); /* record not well-formed */
1489           }
1490           else
1491           {
1492             soa->mname = translate_dot_plus (rh, soa->mname);
1493             soa->rname = translate_dot_plus (rh, soa->rname);
1494             scratch_start = scratch_off;
1495             if (GNUNET_OK !=
1496                 GNUNET_DNSPARSER_builder_add_soa (scratch,
1497                                                   sizeof (scratch),
1498                                                   &scratch_off,
1499                                                   soa))
1500             {
1501               GNUNET_break (0);
1502             }
1503             else
1504             {
1505               rd_new[rd_off].data = &scratch[scratch_start];
1506               rd_new[rd_off].data_size = scratch_off - scratch_start;
1507               rd_off++;
1508             }
1509           }
1510           if (NULL != soa)
1511             GNUNET_DNSPARSER_free_soa (soa);
1512         }
1513         break;
1514       case GNUNET_DNSPARSER_TYPE_MX:
1515         {
1516           struct GNUNET_DNSPARSER_MxRecord *mx;
1517
1518           off = 0;
1519           mx = GNUNET_DNSPARSER_parse_mx (rd[i].data,
1520                                           rd[i].data_size,
1521                                           &off);
1522           if ( (NULL == mx) ||
1523                (off != rd[i].data_size) )
1524           {
1525             GNUNET_break_op (0); /* record not well-formed */
1526           }
1527           else
1528           {
1529             mx->mxhost = translate_dot_plus (rh, mx->mxhost);
1530             scratch_start = scratch_off;
1531             if (GNUNET_OK !=
1532                 GNUNET_DNSPARSER_builder_add_mx (scratch,
1533                                                  sizeof (scratch),
1534                                                  &scratch_off,
1535                                                  mx))
1536             {
1537               GNUNET_break (0);
1538             }
1539             else
1540             {
1541               rd_new[rd_off].data = &scratch[scratch_start];
1542               rd_new[rd_off].data_size = scratch_off - scratch_start;
1543               rd_off++;
1544             }
1545           }
1546           if (NULL != mx)
1547             GNUNET_DNSPARSER_free_mx (mx);
1548         }
1549         break;
1550       case GNUNET_DNSPARSER_TYPE_SRV:
1551         {
1552           struct GNUNET_DNSPARSER_SrvRecord *srv;
1553
1554           off = 0;
1555           /* FIXME: passing rh->name here is is not necessarily what we want
1556              (SRV support not finished) */
1557           srv = GNUNET_DNSPARSER_parse_srv (rh->name,
1558                                             rd[i].data,
1559                                             rd[i].data_size,
1560                                             &off);
1561           if ( (NULL == srv) ||
1562                (off != rd[i].data_size) )
1563           {
1564             GNUNET_break_op (0); /* record not well-formed */
1565           }
1566           else
1567           {
1568             srv->domain_name = translate_dot_plus (rh, srv->domain_name);
1569             srv->target = translate_dot_plus (rh, srv->target);
1570             scratch_start = scratch_off;
1571             if (GNUNET_OK !=
1572                 GNUNET_DNSPARSER_builder_add_srv (scratch,
1573                                                   sizeof (scratch),
1574                                                   &scratch_off,
1575                                                   srv))
1576             {
1577               GNUNET_break (0);
1578             }
1579             else
1580             {
1581               rd_new[rd_off].data = &scratch[scratch_start];
1582               rd_new[rd_off].data_size = scratch_off - scratch_start;
1583               rd_off++;
1584             }
1585           }
1586           if (NULL != srv)
1587             GNUNET_DNSPARSER_free_srv (srv);
1588         }
1589         break;
1590       case GNUNET_GNSRECORD_TYPE_PKEY:
1591         {
1592           struct GNUNET_CRYPTO_EcdsaPublicKey pub;
1593
1594           if (rd[i].data_size != sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey))
1595           {
1596             GNUNET_break_op (0);
1597             break;
1598           }
1599           memcpy (&pub, rd[i].data, rd[i].data_size);
1600
1601           /* tigger shortening */
1602           if (NULL != rh->shorten_key)
1603           {
1604             GNS_shorten_start (rh->ac_tail->label,
1605                                &pub,
1606                                rh->shorten_key);
1607           }
1608           rd_off++;
1609           if (GNUNET_GNSRECORD_TYPE_PKEY != rh->record_type)
1610           {
1611             /* try to resolve "+" */
1612             struct AuthorityChain *ac;
1613
1614             ac = GNUNET_new (struct AuthorityChain);
1615             ac->rh = rh;
1616             ac->gns_authority = GNUNET_YES;
1617             ac->authority_info.gns_authority = pub;
1618             ac->label = GNUNET_strdup (GNUNET_GNS_MASTERZONE_STR);
1619             GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1620                                               rh->ac_tail,
1621                                               ac);
1622             rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1623                                                     rh);
1624             return;
1625           }
1626         }
1627         break;
1628       case GNUNET_GNSRECORD_TYPE_GNS2DNS:
1629         {
1630           /* delegation to DNS */
1631           GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1632                       "Found GNS2DNS record, delegating to DNS!\n");
1633           goto do_recurse;
1634         }
1635       default:
1636         rd_off++;
1637         break;
1638       }
1639     }
1640
1641     /* yes, we are done, return result */
1642     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1643                 "Returning GNS response for `%s' with %u answers\n",
1644                 rh->ac_tail->label,
1645                 rd_off);
1646     rh->proc (rh->proc_cls, rd_off, rd_new);
1647     GNS_resolver_lookup_cancel (rh);
1648     return;
1649   }
1650  do_recurse:
1651   /* need to recurse, check if we can */
1652   for (i=0;i<rd_count;i++)
1653   {
1654     switch (rd[i].record_type)
1655     {
1656     case GNUNET_GNSRECORD_TYPE_PKEY:
1657       /* delegation to another zone */
1658       if (sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey) !=
1659           rd[i].data_size)
1660       {
1661         GNUNET_break_op (0);
1662         rh->proc (rh->proc_cls, 0, NULL);
1663         GNS_resolver_lookup_cancel (rh);
1664         return;
1665       }
1666       /* expand authority chain */
1667       ac = GNUNET_new (struct AuthorityChain);
1668       ac->rh = rh;
1669       ac->gns_authority = GNUNET_YES;
1670       memcpy (&ac->authority_info.gns_authority,
1671               rd[i].data,
1672               sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey));
1673       ac->label = resolver_lookup_get_next_label (rh);
1674       /* tigger shortening */
1675       if (NULL != rh->shorten_key)
1676         GNS_shorten_start (rh->ac_tail->label,
1677                            &ac->authority_info.gns_authority,
1678                            rh->shorten_key);
1679       /* add AC to tail */
1680       GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1681                                         rh->ac_tail,
1682                                         ac);
1683       /* recurse */
1684       rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1685                                               rh);
1686       return;
1687     case GNUNET_GNSRECORD_TYPE_GNS2DNS:
1688       {
1689         /* resolution continues within DNS */
1690         struct Gns2DnsContext *g2dc;
1691         char *ip;
1692         char *at;
1693         char *cp;
1694         char *ns;
1695
1696         cp = GNUNET_strndup (rd[i].data,
1697                              rd[i].data_size);
1698         at = strchr (cp, '@');
1699         if (NULL == at)
1700         {
1701           GNUNET_break_op (0);
1702           rh->proc (rh->proc_cls, 0, NULL);
1703           GNS_resolver_lookup_cancel (rh);
1704           return;
1705         }
1706         *at = '\0';
1707         off = 0;
1708         ns = GNUNET_DNSPARSER_parse_name (cp,
1709                                           strlen (cp),
1710                                           &off);
1711         if ( (NULL == ns) ||
1712              (off != strlen (cp)) )
1713         {
1714           GNUNET_break_op (0); /* record not well-formed */
1715           rh->proc (rh->proc_cls, 0, NULL);
1716           GNS_resolver_lookup_cancel (rh);
1717           GNUNET_free (cp);
1718           return;
1719         }
1720         off++; /* skip '@' */
1721         ip = GNUNET_DNSPARSER_parse_name (cp,
1722                                           strlen (at + 1),
1723                                           &off);
1724         if ( (NULL == ip) ||
1725              (off != rd[i].data_size) )
1726         {
1727           GNUNET_break_op (0); /* record not well-formed */
1728           rh->proc (rh->proc_cls, 0, NULL);
1729           GNS_resolver_lookup_cancel (rh);
1730           GNUNET_free (ns);
1731           GNUNET_free (cp);
1732           return;
1733         }
1734         GNUNET_free (cp);
1735         /* resolve 'ip' to determine the IP(s) of the DNS
1736            resolver to use */
1737         g2dc = GNUNET_new (struct Gns2DnsContext);
1738         g2dc->ns = ns;
1739         g2dc->rh = GNUNET_new (struct GNS_ResolverHandle);
1740         g2dc->rh->authority_zone = rh->ac_tail->authority_info.gns_authority;
1741         g2dc->rh->name = ip;
1742         g2dc->rh->name_resolution_pos = strlen (ip);
1743         g2dc->rh->proc = &handle_gns2dns_result;
1744         g2dc->rh->proc_cls = rh;
1745         g2dc->rh->record_type = GNUNET_GNSRECORD_TYPE_ANY;
1746         g2dc->rh->only_cached = GNUNET_NO;
1747         g2dc->rh->loop_limiter = rh->loop_limiter + 1;
1748         rh->g2dc = g2dc;
1749         start_resolver_lookup (g2dc->rh);
1750         return;
1751       }
1752     case GNUNET_DNSPARSER_TYPE_CNAME:
1753       {
1754         char *cname;
1755
1756         off = 0;
1757         cname = GNUNET_DNSPARSER_parse_name (rd[i].data,
1758                                              rd[i].data_size,
1759                                              &off);
1760         if ( (NULL == cname) ||
1761              (off != rd[i].data_size) )
1762         {
1763           GNUNET_break_op (0); /* record not well-formed */
1764           rh->proc (rh->proc_cls, 0, NULL);
1765           GNS_resolver_lookup_cancel (rh);
1766           GNUNET_free_non_null (cname);
1767           return;
1768         }
1769         handle_gns_cname_result (rh,
1770                                  cname);
1771         GNUNET_free (cname);
1772         return;
1773       }
1774       /* FIXME: handle DNAME */
1775     default:
1776       /* skip */
1777       break;
1778     }
1779   }
1780   GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1781               _("GNS lookup recursion failed (no delegation record found)\n"));
1782   rh->proc (rh->proc_cls, 0, NULL);
1783   GNS_resolver_lookup_cancel (rh);
1784 }
1785
1786
1787 /**
1788  * Function called once the namestore has completed the request for
1789  * caching a block.
1790  *
1791  * @param cls closure with the `struct CacheOps`
1792  * @param success #GNUNET_OK on success
1793  * @param emsg error message
1794  */
1795 static void
1796 namecache_cache_continuation (void *cls,
1797                               int32_t success,
1798                               const char *emsg)
1799 {
1800   struct CacheOps *co = cls;
1801
1802   co->namecache_qe_cache = NULL;
1803   if (NULL != emsg)
1804     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1805                 _("Failed to cache GNS resolution: %s\n"),
1806                 emsg);
1807   GNUNET_CONTAINER_DLL_remove (co_head,
1808                                co_tail,
1809                                co);
1810   GNUNET_free (co);
1811 }
1812
1813
1814 /**
1815  * Iterator called on each result obtained for a DHT
1816  * operation that expects a reply
1817  *
1818  * @param cls closure with the `struct GNS_ResolverHandle`
1819  * @param exp when will this value expire
1820  * @param key key of the result
1821  * @param get_path peers on reply path (or NULL if not recorded)
1822  *                 [0] = datastore's first neighbor, [length - 1] = local peer
1823  * @param get_path_length number of entries in @a get_path
1824  * @param put_path peers on the PUT path (or NULL if not recorded)
1825  *                 [0] = origin, [length - 1] = datastore
1826  * @param put_path_length number of entries in @a put_path
1827  * @param type type of the result
1828  * @param size number of bytes in data
1829  * @param data pointer to the result data
1830  */
1831 static void
1832 handle_dht_response (void *cls,
1833                      struct GNUNET_TIME_Absolute exp,
1834                      const struct GNUNET_HashCode *key,
1835                      const struct GNUNET_PeerIdentity *get_path,
1836                      unsigned int get_path_length,
1837                      const struct GNUNET_PeerIdentity *put_path,
1838                      unsigned int put_path_length,
1839                      enum GNUNET_BLOCK_Type type,
1840                      size_t size, const void *data)
1841 {
1842   struct GNS_ResolverHandle *rh = cls;
1843   struct AuthorityChain *ac = rh->ac_tail;
1844   const struct GNUNET_GNSRECORD_Block *block;
1845   struct CacheOps *co;
1846
1847   GNUNET_DHT_get_stop (rh->get_handle);
1848   rh->get_handle = NULL;
1849   GNUNET_CONTAINER_heap_remove_node (rh->dht_heap_node);
1850   rh->dht_heap_node = NULL;
1851   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1852               "Handling response from the DHT\n");
1853   if (size < sizeof (struct GNUNET_GNSRECORD_Block))
1854   {
1855     /* how did this pass DHT block validation!? */
1856     GNUNET_break (0);
1857     rh->proc (rh->proc_cls, 0, NULL);
1858     GNS_resolver_lookup_cancel (rh);
1859     return;
1860   }
1861   block = data;
1862   if (size !=
1863       ntohl (block->purpose.size) +
1864       sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey) +
1865       sizeof (struct GNUNET_CRYPTO_EcdsaSignature))
1866   {
1867     /* how did this pass DHT block validation!? */
1868     GNUNET_break (0);
1869     rh->proc (rh->proc_cls, 0, NULL);
1870     GNS_resolver_lookup_cancel (rh);
1871     return;
1872   }
1873   if (GNUNET_OK !=
1874       GNUNET_GNSRECORD_block_decrypt (block,
1875                                       &ac->authority_info.gns_authority,
1876                                       ac->label,
1877                                       &handle_gns_resolution_result,
1878                                       rh))
1879   {
1880     GNUNET_break_op (0); /* block was ill-formed */
1881     rh->proc (rh->proc_cls, 0, NULL);
1882     GNS_resolver_lookup_cancel (rh);
1883     return;
1884   }
1885   if (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us)
1886   {
1887     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1888                 "Received expired block from the DHT, will not cache it.\n");
1889     return;
1890   }
1891   /* Cache well-formed blocks */
1892   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1893               "Caching response from the DHT in namestore\n");
1894   co = GNUNET_new (struct CacheOps);
1895   co->namecache_qe_cache = GNUNET_NAMECACHE_block_cache (namecache_handle,
1896                                                          block,
1897                                                          &namecache_cache_continuation,
1898                                                          co);
1899   GNUNET_CONTAINER_DLL_insert (co_head,
1900                                co_tail,
1901                                co);
1902 }
1903
1904
1905 /**
1906  * Process a record that was stored in the namestore.
1907  *
1908  * @param cls closure with the `struct GNS_ResolverHandle`
1909  * @param block block that was stored in the namestore
1910  */
1911 static void
1912 handle_namestore_block_response (void *cls,
1913                                  const struct GNUNET_GNSRECORD_Block *block)
1914 {
1915   struct GNS_ResolverHandle *rh = cls;
1916   struct GNS_ResolverHandle *rx;
1917   struct AuthorityChain *ac = rh->ac_tail;
1918   const char *label = ac->label;
1919   const struct GNUNET_CRYPTO_EcdsaPublicKey *auth = &ac->authority_info.gns_authority;
1920   struct GNUNET_HashCode query;
1921
1922   GNUNET_GNSRECORD_query_from_public_key (auth,
1923                                           label,
1924                                           &query);
1925   GNUNET_assert (NULL != rh->namecache_qe);
1926   rh->namecache_qe = NULL;
1927   if ( (GNUNET_NO == rh->only_cached) &&
1928        ( (NULL == block) ||
1929          (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us) ) )
1930   {
1931     /* Namestore knows nothing; try DHT lookup */
1932     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1933                 "Starting DHT lookup for `%s' in zone %s\n",
1934                 ac->label,
1935                 GNUNET_GNSRECORD_z2s (&ac->authority_info.gns_authority));
1936     GNUNET_assert (NULL == rh->get_handle);
1937     rh->get_handle = GNUNET_DHT_get_start (dht_handle,
1938                                            GNUNET_BLOCK_TYPE_GNS_NAMERECORD,
1939                                            &query,
1940                                            DHT_GNS_REPLICATION_LEVEL,
1941                                            GNUNET_DHT_RO_DEMULTIPLEX_EVERYWHERE,
1942                                            NULL, 0,
1943                                            &handle_dht_response, rh);
1944     rh->dht_heap_node = GNUNET_CONTAINER_heap_insert (dht_lookup_heap,
1945                                                       rh,
1946                                                       GNUNET_TIME_absolute_get ().abs_value_us);
1947     if (GNUNET_CONTAINER_heap_get_size (dht_lookup_heap) > max_allowed_background_queries)
1948     {
1949       /* fail longest-standing DHT request */
1950       rx = GNUNET_CONTAINER_heap_peek (dht_lookup_heap);
1951       GNUNET_assert (NULL != rx);
1952       rx->proc (rx->proc_cls, 0, NULL);
1953       GNS_resolver_lookup_cancel (rx);
1954     }
1955     return;
1956   }
1957   if ( (NULL == block) ||
1958        (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us) )
1959   {
1960     /* DHT not permitted and no local result, fail */
1961     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1962                 "Resolution failed for `%s' in zone %s (DHT lookup not permitted by configuration)\n",
1963                 ac->label,
1964                 GNUNET_GNSRECORD_z2s (&ac->authority_info.gns_authority));
1965     rh->proc (rh->proc_cls, 0, NULL);
1966     GNS_resolver_lookup_cancel (rh);
1967     return;
1968   }
1969   if (GNUNET_OK !=
1970       GNUNET_GNSRECORD_block_decrypt (block,
1971                                       auth,
1972                                       label,
1973                                       &handle_gns_resolution_result,
1974                                       rh))
1975   {
1976     GNUNET_break_op (0); /* block was ill-formed */
1977     rh->proc (rh->proc_cls, 0, NULL);
1978     GNS_resolver_lookup_cancel (rh);
1979     return;
1980   }
1981 }
1982
1983
1984 /**
1985  * Lookup tail of our authority chain in the namestore.
1986  *
1987  * @param rh query we are processing
1988  */
1989 static void
1990 recursive_gns_resolution_namestore (struct GNS_ResolverHandle *rh)
1991 {
1992   struct AuthorityChain *ac = rh->ac_tail;
1993   struct GNUNET_HashCode query;
1994
1995   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1996               "Starting GNS resolution for `%s' in zone %s\n",
1997               ac->label,
1998               GNUNET_GNSRECORD_z2s (&ac->authority_info.gns_authority));
1999   GNUNET_GNSRECORD_query_from_public_key (&ac->authority_info.gns_authority,
2000                                           ac->label,
2001                                           &query);
2002   rh->namecache_qe = GNUNET_NAMECACHE_lookup_block (namecache_handle,
2003                                                     &query,
2004                                                     &handle_namestore_block_response,
2005                                                     rh);
2006   GNUNET_assert (NULL != rh->namecache_qe);
2007 }
2008
2009
2010 /**
2011  * Function called with the result from a revocation check.
2012  *
2013  * @param cls the `struct GNS_ResovlerHandle`
2014  * @param is_valid #GNUNET_YES if the zone was not yet revoked
2015  */
2016 static void
2017 handle_revocation_result (void *cls,
2018                           int is_valid)
2019 {
2020   struct GNS_ResolverHandle *rh = cls;
2021   struct AuthorityChain *ac = rh->ac_tail;
2022
2023   rh->rev_check = NULL;
2024   if (GNUNET_YES != is_valid)
2025   {
2026     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
2027                 _("Zone %s was revoked, resolution fails\n"),
2028                 GNUNET_GNSRECORD_z2s (&ac->authority_info.gns_authority));
2029     rh->proc (rh->proc_cls, 0, NULL);
2030     GNS_resolver_lookup_cancel (rh);
2031     return;
2032   }
2033   recursive_gns_resolution_namestore (rh);
2034 }
2035
2036
2037 /**
2038  * Perform revocation check on tail of our authority chain.
2039  *
2040  * @param rh query we are processing
2041  */
2042 static void
2043 recursive_gns_resolution_revocation (struct GNS_ResolverHandle *rh)
2044 {
2045   struct AuthorityChain *ac = rh->ac_tail;
2046
2047   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2048               "Starting revocation check for zone %s\n",
2049               GNUNET_GNSRECORD_z2s (&ac->authority_info.gns_authority));
2050   rh->rev_check = GNUNET_REVOCATION_query (cfg,
2051                                            &ac->authority_info.gns_authority,
2052                                            &handle_revocation_result,
2053                                            rh);
2054   GNUNET_assert (NULL != rh->rev_check);
2055 }
2056
2057
2058 /**
2059  * Task scheduled to continue with the resolution process.
2060  *
2061  * @param cls the `struct GNS_ResolverHandle` of the resolution
2062  * @param tc task context
2063  */
2064 static void
2065 recursive_resolution (void *cls,
2066                       const struct GNUNET_SCHEDULER_TaskContext *tc)
2067 {
2068   struct GNS_ResolverHandle *rh = cls;
2069
2070   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
2071   if (MAX_RECURSION < rh->loop_limiter++)
2072   {
2073     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
2074                 "Encountered unbounded recursion resolving `%s'\n",
2075                 rh->name);
2076     rh->proc (rh->proc_cls, 0, NULL);
2077     GNS_resolver_lookup_cancel (rh);
2078     return;
2079   }
2080   if (GNUNET_YES == rh->ac_tail->gns_authority)
2081     recursive_gns_resolution_revocation (rh);
2082   else
2083     recursive_dns_resolution (rh);
2084 }
2085
2086
2087 /**
2088  * Begin the resolution process from 'name', starting with
2089  * the identification of the zone specified by 'name'.
2090  *
2091  * @param rh resolution to perform
2092  */
2093 static void
2094 start_resolver_lookup (struct GNS_ResolverHandle *rh)
2095 {
2096   struct AuthorityChain *ac;
2097   char *y;
2098   struct in_addr v4;
2099   struct in6_addr v6;
2100
2101   if (1 == inet_pton (AF_INET,
2102                       rh->name,
2103                       &v4))
2104   {
2105     /* name is IPv4 address, pretend it's an A record */
2106     struct GNUNET_GNSRECORD_Data rd;
2107
2108     rd.data = &v4;
2109     rd.data_size = sizeof (v4);
2110     rd.expiration_time = UINT64_MAX;
2111     rd.record_type = GNUNET_DNSPARSER_TYPE_A;
2112     rd.flags = 0;
2113     rh->proc (rh->proc_cls, 1, &rd);
2114     GNS_resolver_lookup_cancel (rh);
2115     return;
2116   }
2117   if (1 == inet_pton (AF_INET6,
2118                       rh->name,
2119                       &v6))
2120   {
2121     /* name is IPv6 address, pretend it's an AAAA record */
2122     struct GNUNET_GNSRECORD_Data rd;
2123
2124     rd.data = &v6;
2125     rd.data_size = sizeof (v6);
2126     rd.expiration_time = UINT64_MAX;
2127     rd.record_type = GNUNET_DNSPARSER_TYPE_AAAA;
2128     rd.flags = 0;
2129     rh->proc (rh->proc_cls, 1, &rd);
2130     GNS_resolver_lookup_cancel (rh);
2131     return;
2132   }
2133   if ( ( (GNUNET_YES == is_canonical (rh->name)) &&
2134          (0 != strcmp (GNUNET_GNS_TLD, rh->name)) ) ||
2135        ( (GNUNET_YES != is_gnu_tld (rh->name)) &&
2136          (GNUNET_YES != is_zkey_tld (rh->name)) ) )
2137   {
2138     /* use standard DNS lookup */
2139     int af;
2140
2141     switch (rh->record_type)
2142     {
2143     case GNUNET_DNSPARSER_TYPE_A:
2144       af = AF_INET;
2145       break;
2146     case GNUNET_DNSPARSER_TYPE_AAAA:
2147       af = AF_INET6;
2148       break;
2149     default:
2150       af = AF_UNSPEC;
2151       break;
2152     }
2153     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2154                 "Doing standard DNS lookup for `%s'\n",
2155                 rh->name);
2156     rh->std_resolve = GNUNET_RESOLVER_ip_get (rh->name,
2157                                               af,
2158                                               DNS_LOOKUP_TIMEOUT,
2159                                               &handle_dns_result,
2160                                               rh);
2161     return;
2162   }
2163   if (is_zkey_tld (rh->name))
2164   {
2165     /* Name ends with ".zkey", try to replace authority zone with zkey
2166        authority */
2167     GNUNET_free (resolver_lookup_get_next_label (rh)); /* will return "zkey" */
2168     y = resolver_lookup_get_next_label (rh); /* will return 'y' coordinate */
2169     if ( (NULL == y) ||
2170          (GNUNET_OK !=
2171           GNUNET_CRYPTO_ecdsa_public_key_from_string (y,
2172                                                       strlen (y),
2173                                                       &rh->authority_zone)) )
2174     {
2175       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
2176                   _("Hostname `%s' is not well-formed, resolution fails\n"),
2177                   rh->name);
2178       rh->task_id = GNUNET_SCHEDULER_add_now (&fail_resolution, rh);
2179     }
2180     GNUNET_free_non_null (y);
2181   }
2182   else
2183   {
2184     /* Name ends with ".gnu", eat ".gnu" and continue with resolution */
2185     GNUNET_free (resolver_lookup_get_next_label (rh));
2186   }
2187   ac = GNUNET_new (struct AuthorityChain);
2188   ac->rh = rh;
2189   ac->label = resolver_lookup_get_next_label (rh);
2190   if (NULL == ac->label)
2191     /* name was just "gnu", so we default to label '+' */
2192     ac->label = GNUNET_strdup (GNUNET_GNS_MASTERZONE_STR);
2193   ac->gns_authority = GNUNET_YES;
2194   ac->authority_info.gns_authority = rh->authority_zone;
2195   GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
2196                                     rh->ac_tail,
2197                                     ac);
2198   rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
2199                                           rh);
2200 }
2201
2202
2203 /**
2204  * Lookup of a record in a specific zone calls lookup result processor
2205  * on result.
2206  *
2207  * @param zone the zone to perform the lookup in
2208  * @param record_type the record type to look up
2209  * @param name the name to look up
2210  * @param shorten_key a private key for use with PSEU import (can be NULL)
2211  * @param only_cached #GNUNET_NO to only check locally not DHT for performance
2212  * @param proc the processor to call on result
2213  * @param proc_cls the closure to pass to @a proc
2214  * @return handle to cancel operation
2215  */
2216 struct GNS_ResolverHandle *
2217 GNS_resolver_lookup (const struct GNUNET_CRYPTO_EcdsaPublicKey *zone,
2218                      uint32_t record_type,
2219                      const char *name,
2220                      const struct GNUNET_CRYPTO_EcdsaPrivateKey *shorten_key,
2221                      int only_cached,
2222                      GNS_ResultProcessor proc, void *proc_cls)
2223 {
2224   struct GNS_ResolverHandle *rh;
2225
2226   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2227               (NULL == shorten_key)
2228               ? "Starting lookup for `%s' with shortening disabled\n"
2229               : "Starting lookup for `%s' with shortening enabled\n",
2230               name);
2231   rh = GNUNET_new (struct GNS_ResolverHandle);
2232   GNUNET_CONTAINER_DLL_insert (rlh_head,
2233                                rlh_tail,
2234                                rh);
2235   rh->authority_zone = *zone;
2236   rh->proc = proc;
2237   rh->proc_cls = proc_cls;
2238   rh->only_cached = only_cached;
2239   rh->record_type = record_type;
2240   rh->name = GNUNET_strdup (name);
2241   rh->name_resolution_pos = strlen (name);
2242   if (NULL != shorten_key)
2243   {
2244     rh->shorten_key = GNUNET_new (struct GNUNET_CRYPTO_EcdsaPrivateKey);
2245     *rh->shorten_key = *shorten_key;
2246   }
2247   start_resolver_lookup (rh);
2248   return rh;
2249 }
2250
2251
2252 /**
2253  * Cancel active resolution (i.e. client disconnected).
2254  *
2255  * @param rh resolution to abort
2256  */
2257 void
2258 GNS_resolver_lookup_cancel (struct GNS_ResolverHandle *rh)
2259 {
2260   struct DnsResult *dr;
2261   struct AuthorityChain *ac;
2262   struct VpnContext *vpn_ctx;
2263
2264   GNUNET_CONTAINER_DLL_remove (rlh_head,
2265                                rlh_tail,
2266                                rh);
2267   while (NULL != (ac = rh->ac_head))
2268   {
2269     GNUNET_CONTAINER_DLL_remove (rh->ac_head,
2270                                  rh->ac_tail,
2271                                  ac);
2272     GNUNET_free (ac->label);
2273     GNUNET_free (ac);
2274   }
2275   if (NULL != rh->g2dc)
2276   {
2277     /* rh->g2dc->rh is NOT in the DLL yet, so to enable us
2278        using GNS_resolver_lookup_cancel here, we need to
2279        add it first... */
2280     if (NULL != rh->g2dc->rh)
2281     {
2282       GNUNET_CONTAINER_DLL_insert (rlh_head,
2283                                    rlh_tail,
2284                                    rh->g2dc->rh);
2285       GNS_resolver_lookup_cancel (rh->g2dc->rh);
2286       rh->g2dc->rh = NULL;
2287     }
2288     GNUNET_free (rh->g2dc->ns);
2289     GNUNET_free (rh->g2dc);
2290     rh->g2dc = NULL;
2291   }
2292   if (GNUNET_SCHEDULER_NO_TASK != rh->task_id)
2293   {
2294     GNUNET_SCHEDULER_cancel (rh->task_id);
2295     rh->task_id = GNUNET_SCHEDULER_NO_TASK;
2296   }
2297   if (NULL != rh->get_handle)
2298   {
2299     GNUNET_DHT_get_stop (rh->get_handle);
2300     rh->get_handle = NULL;
2301   }
2302   if (NULL != rh->dht_heap_node)
2303   {
2304     GNUNET_CONTAINER_heap_remove_node (rh->dht_heap_node);
2305     rh->dht_heap_node = NULL;
2306   }
2307   if (NULL != (vpn_ctx = rh->vpn_ctx))
2308   {
2309     GNUNET_VPN_cancel_request (vpn_ctx->vpn_request);
2310     GNUNET_free (vpn_ctx->rd_data);
2311     GNUNET_free (vpn_ctx);
2312   }
2313   if (NULL != rh->dns_request)
2314   {
2315     GNUNET_DNSSTUB_resolve_cancel (rh->dns_request);
2316     rh->dns_request = NULL;
2317   }
2318   if (NULL != rh->namecache_qe)
2319   {
2320     GNUNET_NAMECACHE_cancel (rh->namecache_qe);
2321     rh->namecache_qe = NULL;
2322   }
2323   if (NULL != rh->rev_check)
2324   {
2325     GNUNET_REVOCATION_query_cancel (rh->rev_check);
2326     rh->rev_check = NULL;
2327   }
2328   if (NULL != rh->std_resolve)
2329   {
2330     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2331                 "Canceling standard DNS resolution\n");
2332     GNUNET_RESOLVER_request_cancel (rh->std_resolve);
2333     rh->std_resolve = NULL;
2334   }
2335   while (NULL != (dr = rh->dns_result_head))
2336   {
2337     GNUNET_CONTAINER_DLL_remove (rh->dns_result_head,
2338                                  rh->dns_result_tail,
2339                                  dr);
2340     GNUNET_free (dr);
2341   }
2342   GNUNET_free_non_null (rh->shorten_key);
2343   GNUNET_free (rh->name);
2344   GNUNET_free (rh);
2345 }
2346
2347
2348 /* ***************** Resolver initialization ********************* */
2349
2350
2351 /**
2352  * Initialize the resolver
2353  *
2354  * @param nc the namecache handle
2355  * @param dht the dht handle
2356  * @param c configuration handle
2357  * @param max_bg_queries maximum number of parallel background queries in dht
2358  */
2359 void
2360 GNS_resolver_init (struct GNUNET_NAMECACHE_Handle *nc,
2361                    struct GNUNET_DHT_Handle *dht,
2362                    const struct GNUNET_CONFIGURATION_Handle *c,
2363                    unsigned long long max_bg_queries)
2364 {
2365   char *dns_ip;
2366
2367   cfg = c;
2368   namecache_handle = nc;
2369   dht_handle = dht;
2370   dht_lookup_heap =
2371     GNUNET_CONTAINER_heap_create (GNUNET_CONTAINER_HEAP_ORDER_MIN);
2372   max_allowed_background_queries = max_bg_queries;
2373   if (GNUNET_OK !=
2374       GNUNET_CONFIGURATION_get_value_string (c,
2375                                              "gns",
2376                                              "DNS_RESOLVER",
2377                                              &dns_ip))
2378   {
2379     /* user did not specify DNS resolver, use 8.8.8.8 */
2380     dns_ip = GNUNET_strdup ("8.8.8.8");
2381   }
2382   dns_handle = GNUNET_DNSSTUB_start (dns_ip);
2383   GNUNET_free (dns_ip);
2384   vpn_handle = GNUNET_VPN_connect (cfg);
2385 }
2386
2387
2388 /**
2389  * Shutdown resolver
2390  */
2391 void
2392 GNS_resolver_done ()
2393 {
2394   struct GNS_ResolverHandle *rh;
2395   struct CacheOps *co;
2396
2397   /* abort active resolutions */
2398   while (NULL != (rh = rlh_head))
2399   {
2400     rh->proc (rh->proc_cls, 0, NULL);
2401     GNS_resolver_lookup_cancel (rh);
2402   }
2403   while (NULL != (co = co_head))
2404   {
2405     GNUNET_CONTAINER_DLL_remove (co_head,
2406                                  co_tail,
2407                                  co);
2408     GNUNET_NAMECACHE_cancel (co->namecache_qe_cache);
2409     GNUNET_free (co);
2410   }
2411   GNUNET_CONTAINER_heap_destroy (dht_lookup_heap);
2412   dht_lookup_heap = NULL;
2413   GNUNET_DNSSTUB_stop (dns_handle);
2414   dns_handle = NULL;
2415   GNUNET_VPN_disconnect (vpn_handle);
2416   vpn_handle = NULL;
2417   dht_handle = NULL;
2418   namecache_handle = NULL;
2419 }
2420
2421
2422 /* *************** common helper functions (do not really belong here) *********** */
2423
2424 /**
2425  * Checks if @a name ends in ".TLD"
2426  *
2427  * @param name the name to check
2428  * @param tld the TLD to check for
2429  * @return GNUNET_YES or GNUNET_NO
2430  */
2431 int
2432 is_tld (const char* name, const char* tld)
2433 {
2434   size_t offset = 0;
2435
2436   if (strlen (name) <= strlen (tld))
2437     return GNUNET_NO;
2438   offset = strlen (name) - strlen (tld);
2439   if (0 != strcmp (name + offset, tld))
2440     return GNUNET_NO;
2441   return GNUNET_YES;
2442 }
2443
2444
2445 /* end of gnunet-service-gns_resolver.c */