src/gns/gnunet-service-gns_resolver.c

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