src/gns/gnunet-service-gns_resolver.c

   1 /*
   2      This file is part of GNUnet.
   3      (C) 2011-2013 Christian Grothoff (and other contributing authors)
   4
   5      GNUnet is free software; you can redistribute it and/or modify
   6      it under the terms of the GNU General Public License as published
   7      by the Free Software Foundation; either version 3, or (at your
   8      option) any later version.
   9
  10      GNUnet is distributed in the hope that it will be useful, but
  11      WITHOUT ANY WARRANTY; without even the implied warranty of
  12      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13      General Public License for more details.
  14
  15      You should have received a copy of the GNU General Public License
  16      along with GNUnet; see the file COPYING.  If not, write to the
  17      Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18      Boston, MA 02111-1307, USA.
  19 */
  20
  21 /**
  22  * @file gns/gnunet-service-gns_resolver.c
  23  * @brief GNU Name System resolver logic
  24  * @author Martin Schanzenbach
  25  * @author Christian Grothoff
  26  *
  27  * TODO:
  28  * - GNS: handle special SRV names --- no delegation, direct lookup;
  29  *        can likely be done in 'resolver_lookup_get_next_label'. (#3003)
  30  * - revocation checks (use CORE-level broadcasts!), (#3004)
  31  * - DNAME support (#3005)
  32  */
  33 #include "platform.h"
  34 #include "gnunet_util_lib.h"
  35 #include "gnunet_dnsstub_lib.h"
  36 #include "gnunet_dht_service.h"
  37 #include "gnunet_namestore_service.h"
  38 #include "gnunet_dns_service.h"
  39 #include "gnunet_resolver_service.h"
  40 #include "gnunet_dnsparser_lib.h"
  41 #include "gnunet_gns_service.h"
  42 #include "gns.h"
  43 #include "gnunet-service-gns_resolver.h"
  44 #include "gnunet-service-gns_shorten.h"
  45 #include "gnunet_vpn_service.h"
  46
  47
  48 /**
  49  * Default DHT timeout for lookups.
  50  */
  51 #define DHT_LOOKUP_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 60)
  52
  53 /**
  54  * Default timeout for DNS lookups.
  55  */
  56 #define DNS_LOOKUP_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)
  57
  58 /**
  59  * Default timeout for VPN redirections.
  60  */
  61 #define VPN_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 30)
  62
  63 /**
  64  * DHT replication level
  65  */
  66 #define DHT_GNS_REPLICATION_LEVEL 5
  67
  68 /**
  69  * How deep do we allow recursions to go before we abort?
  70  */
  71 #define MAX_RECURSION 256
  72
  73
  74 /**
  75  * DLL to hold the authority chain we had to pass in the resolution
  76  * process.
  77  */
  78 struct AuthorityChain
  79 {
  80   /**
  81    * This is a DLL.
  82    */
  83   struct AuthorityChain *prev;
  84
  85   /**
  86    * This is a DLL.
  87    */
  88   struct AuthorityChain *next;
  89
  90   /**
  91    * Resolver handle this entry in the chain belongs to.
  92    */
  93   struct GNS_ResolverHandle *rh;
  94
  95   /**
  96    * label/name corresponding to the authority
  97    */
  98   char *label;
  99
 100   /**
 101    * #GNUNET_YES if the authority was a GNS authority,
 102    * #GNUNET_NO if the authority was a DNS authority.
 103    */
 104   int gns_authority;
 105
 106   /**
 107    * Information about the resolver authority for this label.
 108    */
 109   union
 110   {
 111
 112     /**
 113      * The zone of the GNS authority
 114      */
 115     struct GNUNET_CRYPTO_EccPublicSignKey gns_authority;
 116
 117     struct
 118     {
 119       /**
 120        * Domain of the DNS resolver that is the authority.
 121        * (appended to construct the DNS name to resolve;
 122        * this is NOT the DNS name of the DNS server!).
 123        */
 124       char name[GNUNET_DNSPARSER_MAX_NAME_LENGTH + 1];
 125
 126       /**
 127        * IP address of the DNS resolver that is authoritative.
 128        * (this implementation currently only supports one
 129        * IP at a time).
 130        */
 131       struct sockaddr_storage dns_ip;
 132
 133     } dns_authority;
 134
 135   } authority_info;
 136
 137 };
 138
 139
 140 /**
 141  * A result we got from DNS.
 142  */
 143 struct DnsResult
 144 {
 145
 146   /**
 147    * Kept in DLL.
 148    */
 149   struct DnsResult *next;
 150
 151   /**
 152    * Kept in DLL.
 153    */
 154   struct DnsResult *prev;
 155
 156   /**
 157    * Binary value stored in the DNS record (appended to this struct)
 158    */
 159   const void *data;
 160
 161   /**
 162    * Expiration time for the DNS record, 0 if we didn't
 163    * get anything useful (i.e. 'gethostbyname' was used).
 164    */
 165   uint64_t expiration_time;
 166
 167   /**
 168    * Number of bytes in 'data'.
 169    */
 170   size_t data_size;
 171
 172   /**
 173    * Type of the GNS/DNS record.
 174    */
 175   uint32_t record_type;
 176
 177 };
 178
 179
 180 /**
 181  * Closure for #vpn_allocation_cb.
 182  */
 183 struct VpnContext
 184 {
 185
 186   /**
 187    * Which resolution process are we processing.
 188    */
 189   struct GNS_ResolverHandle *rh;
 190
 191   /**
 192    * Handle to the VPN request that we were performing.
 193    */
 194   struct GNUNET_VPN_RedirectionRequest *vpn_request;
 195
 196   /**
 197    * Number of records serialized in 'rd_data'.
 198    */
 199   unsigned int rd_count;
 200
 201   /**
 202    * Serialized records.
 203    */
 204   char *rd_data;
 205
 206   /**
 207    * Number of bytes in 'rd_data'.
 208    */
 209   size_t rd_data_size;
 210 };
 211
 212
 213 /**
 214  * Handle to a currenty pending resolution.  On result (positive or
 215  * negative) the #GNS_ResultProcessor is called.
 216  */
 217 struct GNS_ResolverHandle
 218 {
 219
 220   /**
 221    * DLL
 222    */
 223   struct GNS_ResolverHandle *next;
 224
 225   /**
 226    * DLL
 227    */
 228   struct GNS_ResolverHandle *prev;
 229
 230   /**
 231    * The top-level GNS authoritative zone to query
 232    */
 233   struct GNUNET_CRYPTO_EccPublicSignKey authority_zone;
 234
 235   /**
 236    * called when resolution phase finishes
 237    */
 238   GNS_ResultProcessor proc;
 239
 240   /**
 241    * closure passed to proc
 242    */
 243   void* proc_cls;
 244
 245   /**
 246    * Handle for DHT lookups. should be NULL if no lookups are in progress
 247    */
 248   struct GNUNET_DHT_GetHandle *get_handle;
 249
 250   /**
 251    * Handle to a VPN request, NULL if none is active.
 252    */
 253   struct VpnContext *vpn_ctx;
 254
 255   /**
 256    * Socket for a DNS request, NULL if none is active.
 257    */
 258   struct GNUNET_DNSSTUB_RequestSocket *dns_request;
 259
 260   /**
 261    * Handle for standard DNS resolution, NULL if none is active.
 262    */
 263   struct GNUNET_RESOLVER_RequestHandle *std_resolve;
 264
 265   /**
 266    * Pending Namestore task
 267    */
 268   struct GNUNET_NAMESTORE_QueueEntry *namestore_qe;
 269
 270   /**
 271    * Heap node associated with this lookup.  Used to limit number of
 272    * concurrent requests.
 273    */
 274   struct GNUNET_CONTAINER_HeapNode *dht_heap_node;
 275
 276   /**
 277    * DLL to store the authority chain
 278    */
 279   struct AuthorityChain *ac_head;
 280
 281   /**
 282    * DLL to store the authority chain
 283    */
 284   struct AuthorityChain *ac_tail;
 285
 286   /**
 287    * Private key of the shorten zone, NULL to not shorten.
 288    */
 289   struct GNUNET_CRYPTO_EccPrivateKey *shorten_key;
 290
 291   /**
 292    * ID of a task associated with the resolution process.
 293    */
 294   GNUNET_SCHEDULER_TaskIdentifier task_id;
 295
 296   /**
 297    * The name to resolve
 298    */
 299   char *name;
 300
 301   /**
 302    * DLL of results we got from DNS.
 303    */
 304   struct DnsResult *dns_result_head;
 305
 306   /**
 307    * DLL of results we got from DNS.
 308    */
 309   struct DnsResult *dns_result_tail;
 310
 311   /**
 312    * Current offset in 'name' where we are resolving.
 313    */
 314   size_t name_resolution_pos;
 315
 316   /**
 317    * Use only cache
 318    */
 319   int only_cached;
 320
 321   /**
 322    * Desired type for the resolution.
 323    */
 324   int record_type;
 325
 326   /**
 327    * We increment the loop limiter for each step in a recursive
 328    * resolution.  If it passes our threshold (i.e. due to
 329    * self-recursion in the resolution, i.e CNAME fun), we stop.
 330    */
 331   unsigned int loop_limiter;
 332
 333 };
 334
 335
 336 /**
 337  * Our handle to the namestore service
 338  */
 339 static struct GNUNET_NAMESTORE_Handle *namestore_handle;
 340
 341 /**
 342  * Our handle to the vpn service
 343  */
 344 static struct GNUNET_VPN_Handle *vpn_handle;
 345
 346 /**
 347  * Resolver handle to the dht
 348  */
 349 static struct GNUNET_DHT_Handle *dht_handle;
 350
 351 /**
 352  * Handle to perform DNS lookups.
 353  */
 354 static struct GNUNET_DNSSTUB_Context *dns_handle;
 355
 356 /**
 357  * Heap for limiting parallel DHT lookups
 358  */
 359 static struct GNUNET_CONTAINER_Heap *dht_lookup_heap;
 360
 361 /**
 362  * Maximum amount of parallel queries to the DHT
 363  */
 364 static unsigned long long max_allowed_background_queries;
 365
 366 /**
 367  * Head of resolver lookup list
 368  */
 369 static struct GNS_ResolverHandle *rlh_head;
 370
 371 /**
 372  * Tail of resolver lookup list
 373  */
 374 static struct GNS_ResolverHandle *rlh_tail;
 375
 376 /**
 377  * Global configuration.
 378  */
 379 static const struct GNUNET_CONFIGURATION_Handle *cfg;
 380
 381
 382 /**
 383  * Check if name is in srv format (_x._y.xxx)
 384  *
 385  * @param name
 386  * @return #GNUNET_YES if true
 387  */
 388 static int
 389 is_srv (const char *name)
 390 {
 391   char *ndup;
 392   int ret;
 393
 394   if (*name != '_')
 395     return GNUNET_NO;
 396   if (NULL == strstr (name, "._"))
 397     return GNUNET_NO;
 398   ret = GNUNET_YES;
 399   ndup = GNUNET_strdup (name);
 400   strtok (ndup, ".");
 401   if (NULL == strtok (NULL, "."))
 402     ret = GNUNET_NO;
 403   if (NULL == strtok (NULL, "."))
 404     ret = GNUNET_NO;
 405   if (NULL != strtok (NULL, "."))
 406     ret = GNUNET_NO;
 407   GNUNET_free (ndup);
 408   return ret;
 409 }
 410
 411
 412 /**
 413  * Determine if this name is canonical (is a legal name in a zone, without delegation);
 414  * note that we do not test that the name does not contain illegal characters, we only
 415  * test for delegation.  Note that service records (i.e. _foo._srv) are canonical names
 416  * even though they consist of multiple labels.
 417  *
 418  * Examples:
 419  * a.b.gnu  = not canonical
 420  * a         = canonical
 421  * _foo._srv = canonical
 422  * _f.bar    = not canonical
 423  *
 424  * @param name the name to test
 425  * @return #GNUNET_YES if canonical
 426  */
 427 static int
 428 is_canonical (const char *name)
 429 {
 430   const char *pos;
 431   const char *dot;
 432
 433   if (NULL == strchr (name, '.'))
 434     return GNUNET_YES;
 435   if ('_' != name[0])
 436     return GNUNET_NO;
 437   pos = &name[1];
 438   while (NULL != (dot = strchr (pos, '.')))
 439     if ('_' != dot[1])
 440       return GNUNET_NO;
 441     else
 442       pos = dot + 1;
 443   return GNUNET_YES;
 444 }
 445
 446 /* ************************** Resolution **************************** */
 447
 448 /**
 449  * Exands a name ending in .+ with the zone of origin.
 450  *
 451  * @param rh resolution context
 452  * @param name name to modify (to be free'd or returned)
 453  * @return updated name
 454  */
 455 static char *
 456 translate_dot_plus (struct GNS_ResolverHandle *rh,
 457                     char *name)
 458 {
 459   char *ret;
 460   size_t s_len = strlen (name);
 461
 462   if (0 != strcmp (&name[s_len - 2],
 463                    ".+"))
 464     return name; /* did not end in ".+" */
 465   GNUNET_assert (GNUNET_YES == rh->ac_tail->gns_authority);
 466   GNUNET_asprintf (&ret,
 467                    "%.*s.%s",
 468                    (int) (s_len - 2),
 469                    name,
 470                    GNUNET_NAMESTORE_pkey_to_zkey (&rh->ac_tail->authority_info.gns_authority));
 471   GNUNET_free (name);
 472   return ret;
 473 }
 474
 475
 476 /**
 477  * Task scheduled to asynchronously fail a resolution.
 478  *
 479  * @param cls the 'struct GNS_ResolverHandle' of the resolution to fail
 480  * @param tc task context
 481  */
 482 static void
 483 fail_resolution (void *cls,
 484                  const struct GNUNET_SCHEDULER_TaskContext *tc)
 485 {
 486   struct GNS_ResolverHandle *rh = cls;
 487
 488   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
 489   rh->proc (rh->proc_cls, 0, NULL);
 490   GNS_resolver_lookup_cancel (rh);
 491 }
 492
 493
 494 #if (defined WINDOWS) || (defined DARWIN)
 495 /* Don't have this on W32, here's a naive implementation
 496  * Was somehow removed on OS X ...  */
 497 void *
 498 memrchr (const void *s, int c, size_t n)
 499 {
 500   size_t i;
 501   unsigned char *ucs = (unsigned char *) s;
 502
 503   for (i = n - 1; i >= 0; i--)
 504     if (ucs[i] == c)
 505       return (void *) &ucs[i];
 506   return NULL;
 507 }
 508 #endif
 509
 510
 511 /**
 512  * Get the next, rightmost label from the name that we are trying to resolve,
 513  * and update the resolution position accordingly.
 514  *
 515  * @param rh handle to the resolution operation to get the next label from
 516  * @return NULL if there are no more labels
 517  */
 518 static char *
 519 resolver_lookup_get_next_label (struct GNS_ResolverHandle *rh)
 520 {
 521   const char *rp;
 522   const char *dot;
 523   size_t len;
 524
 525   if (0 == rh->name_resolution_pos)
 526     return NULL;
 527   dot = memrchr (rh->name, (int) '.', rh->name_resolution_pos);
 528   if (NULL == dot)
 529   {
 530     /* done, this was the last one */
 531     len = rh->name_resolution_pos;
 532     rp = rh->name;
 533     rh->name_resolution_pos = 0;
 534   }
 535   else
 536   {
 537     /* advance by one label */
 538     len = rh->name_resolution_pos - (dot - rh->name) - 1;
 539     rp = dot + 1;
 540     rh->name_resolution_pos = dot - rh->name;
 541   }
 542   return GNUNET_strndup (rp, len);
 543 }
 544
 545
 546 /**
 547  * Gives the cummulative result obtained to the callback and clean up the request.
 548  *
 549  * @param rh resolution process that has culminated in a result
 550  */
 551 static void
 552 transmit_lookup_dns_result (struct GNS_ResolverHandle *rh)
 553 {
 554   struct DnsResult *pos;
 555   unsigned int n;
 556   unsigned int i;
 557
 558   n = 0;
 559   for (pos = rh->dns_result_head; NULL != pos; pos = pos->next)
 560     n++;
 561   {
 562     struct GNUNET_NAMESTORE_RecordData rd[n];
 563
 564     i = 0;
 565     for (pos = rh->dns_result_head; NULL != pos; pos = pos->next)
 566     {
 567       rd[i].data = pos->data;
 568       rd[i].data_size = pos->data_size;
 569       rd[i].record_type = pos->record_type;
 570       if (0 == pos->expiration_time)
 571       {
 572         rd[i].flags = GNUNET_NAMESTORE_RF_RELATIVE_EXPIRATION;
 573         rd[i].expiration_time = 0;
 574       }
 575       else
 576       {
 577         rd[i].flags = GNUNET_NAMESTORE_RF_NONE;
 578         rd[i].expiration_time = pos->expiration_time;
 579       }
 580       i++;
 581     }
 582     GNUNET_assert (i == n);
 583     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 584                 "Transmitting standard DNS result with %u records\n",
 585                 n);
 586     rh->proc (rh->proc_cls,
 587               n,
 588               rd);
 589   }
 590   GNS_resolver_lookup_cancel (rh);
 591 }
 592
 593
 594 /**
 595  * Add a result from DNS to the records to be returned to the application.
 596  *
 597  * @param rh resolution request to extend with a result
 598  * @param expiration_time expiration time for the answer
 599  * @param record_type DNS record type of the answer
 600  * @param data_size number of bytes in @a data
 601  * @param data binary data to return in DNS record
 602  */
 603 static void
 604 add_dns_result (struct GNS_ResolverHandle *rh,
 605                 uint64_t expiration_time,
 606                 uint32_t record_type,
 607                 size_t data_size,
 608                 const void *data)
 609 {
 610   struct DnsResult *res;
 611
 612   res = GNUNET_malloc (sizeof (struct DnsResult) + data_size);
 613   res->expiration_time = expiration_time;
 614   res->data_size = data_size;
 615   res->record_type = record_type;
 616   res->data = &res[1];
 617   memcpy (&res[1], data, data_size);
 618   GNUNET_CONTAINER_DLL_insert (rh->dns_result_head,
 619                                rh->dns_result_tail,
 620                                res);
 621 }
 622
 623
 624 /**
 625  * We had to do a DNS lookup.  Convert the result (if any) and return
 626  * it.
 627  *
 628  * @param cls closure with the 'struct GNS_ResolverHandle'
 629  * @param addr one of the addresses of the host, NULL for the last address
 630  * @param addrlen length of the address
 631  */
 632 static void
 633 handle_dns_result (void *cls,
 634                    const struct sockaddr *addr,
 635                    socklen_t addrlen)
 636 {
 637   struct GNS_ResolverHandle *rh = cls;
 638   const struct sockaddr_in *sa4;
 639   const struct sockaddr_in6 *sa6;
 640
 641   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 642               "Received %u bytes of DNS IP data\n",
 643               addrlen);
 644   if (NULL == addr)
 645   {
 646     rh->std_resolve = NULL;
 647     transmit_lookup_dns_result (rh);
 648     return;
 649   }
 650   switch (addr->sa_family)
 651   {
 652   case AF_INET:
 653     sa4 = (const struct sockaddr_in *) addr;
 654     add_dns_result (rh,
 655                     0 /* expiration time is unknown */,
 656                     GNUNET_DNSPARSER_TYPE_A,
 657                     sizeof (struct in_addr),
 658                     &sa4->sin_addr);
 659     break;
 660   case AF_INET6:
 661     sa6 = (const struct sockaddr_in6 *) addr;
 662     add_dns_result (rh,
 663                     0 /* expiration time is unknown */,
 664                     GNUNET_DNSPARSER_TYPE_AAAA,
 665                     sizeof (struct in6_addr),
 666                     &sa6->sin6_addr);
 667     break;
 668   default:
 669     GNUNET_break (0);
 670     break;
 671   }
 672 }
 673
 674
 675 /**
 676  * Task scheduled to continue with the resolution process.
 677  *
 678  * @param cls the 'struct GNS_ResolverHandle' of the resolution
 679  * @param tc task context
 680  */
 681 static void
 682 recursive_resolution (void *cls,
 683                       const struct GNUNET_SCHEDULER_TaskContext *tc);
 684
 685
 686 /**
 687  * Begin the resolution process from 'name', starting with
 688  * the identification of the zone specified by 'name'.
 689  *
 690  * @param rh resolution to perform
 691  */
 692 static void
 693 start_resolver_lookup (struct GNS_ResolverHandle *rh);
 694
 695
 696 /**
 697  * Function called with the result of a DNS resolution.
 698  *
 699  * @param cls the request handle of the resolution that
 700  *        we were attempting to make
 701  * @param rs socket that received the response
 702  * @param dns dns response, never NULL
 703  * @param dns_len number of bytes in @a dns
 704  */
 705 static void
 706 dns_result_parser (void *cls,
 707                    struct GNUNET_DNSSTUB_RequestSocket *rs,
 708                    const struct GNUNET_TUN_DnsHeader *dns,
 709                    size_t dns_len)
 710 {
 711   struct GNS_ResolverHandle *rh = cls;
 712   struct GNUNET_DNSPARSER_Packet *p;
 713   const struct GNUNET_DNSPARSER_Record *rec;
 714   unsigned int rd_count;
 715   unsigned int i;
 716
 717   rh->dns_request = NULL;
 718   GNUNET_SCHEDULER_cancel (rh->task_id);
 719   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
 720   p = GNUNET_DNSPARSER_parse ((const char *) dns,
 721                               dns_len);
 722   if (NULL == p)
 723   {
 724     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
 725                 _("Failed to parse DNS response\n"));
 726     rh->proc (rh->proc_cls, 0, NULL);
 727     GNS_resolver_lookup_cancel (rh);
 728     return;
 729   }
 730
 731   if ( (p->num_answers > 0) &&
 732        (GNUNET_DNSPARSER_TYPE_CNAME == p->answers[0].type) &&
 733        (GNUNET_DNSPARSER_TYPE_CNAME != rh->record_type) )
 734     {
 735       GNUNET_free (rh->name);
 736       rh->name = GNUNET_strdup (p->answers[0].data.hostname);
 737       start_resolver_lookup (rh);
 738       GNUNET_DNSPARSER_free_packet (p);
 739       return;
 740     }
 741   /* FIXME: add DNAME support */
 742
 743   /* convert from (parsed) DNS to (binary) GNS format! */
 744   rd_count = p->num_answers + p->num_authority_records + p->num_additional_records;
 745   {
 746     struct GNUNET_NAMESTORE_RecordData rd[rd_count];
 747     unsigned int skip;
 748     char buf[UINT16_MAX];
 749     size_t buf_off;
 750
 751     buf_off = 0;
 752     skip = 0;
 753     memset (rd, 0, sizeof (rd));
 754     for (i=0;i<rd_count;i++)
 755     {
 756       if (i < p->num_answers)
 757         rec = &p->answers[i];
 758       else if (i < p->num_answers + p->num_authority_records)
 759         rec = &p->authority_records[i - p->num_answers];
 760       else
 761         rec = &p->authority_records[i - p->num_answers - p->num_authority_records];
 762       /* As we copied the full DNS name to 'rh->ac_tail->label', this
 763          should be the correct check to see if this record is actually
 764          a record for our label... */
 765       if (0 != strcmp (rec->name,
 766                        rh->ac_tail->label))
 767       {
 768         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 769                     "Dropping record `%s', does not match desired name `%s'\n",
 770                     rec->name,
 771                     rh->ac_tail->label);
 772         skip++;
 773         continue;
 774       }
 775       rd[i - skip].record_type = rec->type;
 776       rd[i - skip].expiration_time = rec->expiration_time.abs_value_us;
 777       switch (rec->type)
 778       {
 779       case GNUNET_DNSPARSER_TYPE_A:
 780         if (rec->data.raw.data_len != sizeof (struct in_addr))
 781         {
 782           GNUNET_break_op (0);
 783           skip++;
 784           continue;
 785         }
 786         rd[i - skip].data_size = rec->data.raw.data_len;
 787         rd[i - skip].data = rec->data.raw.data;
 788         break;
 789       case GNUNET_DNSPARSER_TYPE_AAAA:
 790         if (rec->data.raw.data_len != sizeof (struct in6_addr))
 791         {
 792           GNUNET_break_op (0);
 793           skip++;
 794           continue;
 795         }
 796         rd[i - skip].data_size = rec->data.raw.data_len;
 797         rd[i - skip].data = rec->data.raw.data;
 798         break;
 799       case GNUNET_DNSPARSER_TYPE_CNAME:
 800       case GNUNET_DNSPARSER_TYPE_PTR:
 801       case GNUNET_DNSPARSER_TYPE_NS:
 802         if (GNUNET_OK !=
 803             GNUNET_DNSPARSER_builder_add_name (buf,
 804                                                sizeof (buf),
 805                                                &buf_off,
 806                                                rec->data.hostname))
 807         {
 808           GNUNET_break (0);
 809           skip++;
 810           continue;
 811         }
 812         break;
 813       case GNUNET_DNSPARSER_TYPE_SOA:
 814         if (GNUNET_OK !=
 815             GNUNET_DNSPARSER_builder_add_soa (buf,
 816                                                sizeof (buf),
 817                                                &buf_off,
 818                                                rec->data.soa))
 819         {
 820           GNUNET_break (0);
 821           skip++;
 822           continue;
 823         }
 824         break;
 825       case GNUNET_DNSPARSER_TYPE_MX:
 826         if (GNUNET_OK !=
 827             GNUNET_DNSPARSER_builder_add_mx (buf,
 828                                              sizeof (buf),
 829                                              &buf_off,
 830                                              rec->data.mx))
 831         {
 832           GNUNET_break (0);
 833           skip++;
 834           continue;
 835         }
 836         break;
 837       case GNUNET_DNSPARSER_TYPE_SRV:
 838         if (GNUNET_OK !=
 839             GNUNET_DNSPARSER_builder_add_srv (buf,
 840                                               sizeof (buf),
 841                                               &buf_off,
 842                                               rec->data.srv))
 843         {
 844           GNUNET_break (0);
 845           skip++;
 846           continue;
 847         }
 848         break;
 849       default:
 850         GNUNET_log (GNUNET_ERROR_TYPE_INFO,
 851                     _("Skipping record of unsupported type %d\n"),
 852                     rec->type);
 853         skip++;
 854         continue;
 855       }
 856     }
 857     rh->proc (rh->proc_cls, rd_count - skip, rd);
 858     GNS_resolver_lookup_cancel (rh);
 859   }
 860   GNUNET_DNSPARSER_free_packet (p);
 861 }
 862
 863
 864 /**
 865  * Perform recursive DNS resolution.  Asks the given DNS resolver to
 866  * resolve "rh->dns_name", possibly recursively proceeding following
 867  * NS delegations, CNAMES, etc., until 'rh->loop_limiter' bounds us or
 868  * we find the answer.
 869  *
 870  * @param rh resolution information
 871  */
 872 static void
 873 recursive_dns_resolution (struct GNS_ResolverHandle *rh)
 874 {
 875   struct AuthorityChain *ac;
 876   socklen_t sa_len;
 877   struct GNUNET_DNSPARSER_Query *query;
 878   struct GNUNET_DNSPARSER_Packet *p;
 879   char *dns_request;
 880   size_t dns_request_length;
 881
 882   ac = rh->ac_tail;
 883   GNUNET_assert (NULL != ac);
 884   GNUNET_assert (GNUNET_NO == ac->gns_authority);
 885   switch (((const struct sockaddr *) &ac->authority_info.dns_authority.dns_ip)->sa_family)
 886   {
 887   case AF_INET:
 888     sa_len = sizeof (struct sockaddr_in);
 889     break;
 890   case AF_INET6:
 891     sa_len = sizeof (struct sockaddr_in6);
 892     break;
 893   default:
 894     GNUNET_break (0);
 895     rh->proc (rh->proc_cls, 0, NULL);
 896     GNS_resolver_lookup_cancel (rh);
 897     return;
 898   }
 899   query = GNUNET_new (struct GNUNET_DNSPARSER_Query);
 900   query->name = GNUNET_strdup (ac->label);
 901   query->type = rh->record_type;
 902   query->class = GNUNET_TUN_DNS_CLASS_INTERNET;
 903   p = GNUNET_new (struct GNUNET_DNSPARSER_Packet);
 904   p->queries = query;
 905   p->num_queries = 1;
 906   p->id = (uint16_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
 907                                                UINT16_MAX);
 908   p->flags.opcode = GNUNET_TUN_DNS_OPCODE_QUERY;
 909   p->flags.recursion_desired = 1;
 910   if (GNUNET_OK !=
 911       GNUNET_DNSPARSER_pack (p, 1024, &dns_request, &dns_request_length))
 912   {
 913     GNUNET_break (0);
 914     rh->proc (rh->proc_cls, 0, NULL);
 915     GNS_resolver_lookup_cancel (rh);
 916   }
 917   else
 918   {
 919     rh->dns_request = GNUNET_DNSSTUB_resolve (dns_handle,
 920                                               (const struct sockaddr *) &ac->authority_info.dns_authority.dns_ip,
 921                                               sa_len,
 922                                               dns_request,
 923                                               dns_request_length,
 924                                               &dns_result_parser,
 925                                               rh);
 926     rh->task_id = GNUNET_SCHEDULER_add_delayed (DNS_LOOKUP_TIMEOUT,
 927                                                 &fail_resolution,
 928                                                 rh);
 929   }
 930   GNUNET_free (dns_request);
 931   GNUNET_DNSPARSER_free_packet (p);
 932 }
 933
 934
 935 /**
 936  * We encountered a CNAME record during our resolution.
 937  * Merge it into our chain.
 938  *
 939  * @param rh resolution we are performing
 940  * @param cname value of the cname record we got for the current
 941  *        authority chain tail
 942  */
 943 static void
 944 handle_gns_cname_result (struct GNS_ResolverHandle *rh,
 945                          const char *cname)
 946 {
 947   size_t nlen;
 948   char *res;
 949   struct AuthorityChain *ac;
 950
 951   nlen = strlen (cname);
 952   if ( (nlen > 2) &&
 953        (0 == strcmp (".+",
 954                      &cname[nlen - 2])) )
 955   {
 956     /* CNAME resolution continues relative to current domain */
 957     if (0 == rh->name_resolution_pos)
 958     {
 959       res = GNUNET_strndup (cname, nlen - 2);
 960       rh->name_resolution_pos = nlen - 2;
 961     }
 962     else
 963     {
 964       GNUNET_asprintf (&res,
 965                        "%.*s.%.*s",
 966                        (int) rh->name_resolution_pos,
 967                        rh->name,
 968                        (int) (nlen - 2),
 969                        cname);
 970       rh->name_resolution_pos = strlen (res);
 971     }
 972     GNUNET_free (rh->name);
 973     rh->name = res;
 974     ac = GNUNET_new (struct AuthorityChain);
 975     ac->rh = rh;
 976     ac->gns_authority = GNUNET_YES;
 977     ac->authority_info.gns_authority = rh->ac_tail->authority_info.gns_authority;
 978     ac->label = resolver_lookup_get_next_label (rh);
 979     /* tigger shortening */
 980     if (NULL != rh->shorten_key)
 981       GNS_shorten_start (rh->ac_tail->label,
 982                          &ac->authority_info.gns_authority,
 983                          rh->shorten_key);
 984     /* add AC to tail */
 985     GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
 986                                       rh->ac_tail,
 987                                       ac);
 988     rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
 989                                             rh);
 990     return;
 991   }
 992   /* name is absolute, start from the beginning */
 993   GNUNET_free (rh->name);
 994   rh->name = GNUNET_strdup (cname);
 995   start_resolver_lookup (rh);
 996 }
 997
 998
 999 /**
1000  * Process a records that were decrypted from a block.
1001  *
1002  * @param cls closure with the 'struct GNS_ResolverHandle'
1003  * @param rd_count number of entries in @a rd array
1004  * @param rd array of records with data to store
1005  */
1006 static void
1007 handle_gns_resolution_result (void *cls,
1008                               unsigned int rd_count,
1009                               const struct GNUNET_NAMESTORE_RecordData *rd);
1010
1011
1012 /**
1013  * Callback invoked from the VPN service once a redirection is
1014  * available.  Provides the IP address that can now be used to
1015  * reach the requested destination.  Replaces the "VPN" record
1016  * with the respective A/AAAA record and continues processing.
1017  *
1018  * @param cls closure
1019  * @param af address family, AF_INET or AF_INET6; AF_UNSPEC on error;
1020  *                will match 'result_af' from the request
1021  * @param address IP address (struct in_addr or struct in_addr6, depending on 'af')
1022  *                that the VPN allocated for the redirection;
1023  *                traffic to this IP will now be redirected to the
1024  *                specified target peer; NULL on error
1025  */
1026 static void
1027 vpn_allocation_cb (void *cls,
1028                    int af,
1029                    const void *address)
1030 {
1031   struct VpnContext *vpn_ctx = cls;
1032   struct GNS_ResolverHandle *rh = vpn_ctx->rh;
1033   struct GNUNET_NAMESTORE_RecordData rd[vpn_ctx->rd_count];
1034   unsigned int i;
1035
1036   vpn_ctx->vpn_request = NULL;
1037   rh->vpn_ctx = NULL;
1038   GNUNET_assert (GNUNET_OK ==
1039                  GNUNET_NAMESTORE_records_deserialize (vpn_ctx->rd_data_size,
1040                                                        vpn_ctx->rd_data,
1041                                                        vpn_ctx->rd_count,
1042                                                        rd));
1043   for (i=0;i<vpn_ctx->rd_count;i++)
1044   {
1045     if (GNUNET_NAMESTORE_TYPE_VPN == rd[i].record_type)
1046     {
1047       switch (af)
1048       {
1049       case AF_INET:
1050         rd[i].record_type = GNUNET_DNSPARSER_TYPE_A;
1051         rd[i].data_size = sizeof (struct in_addr);
1052         rd[i].expiration_time = GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT).abs_value_us;
1053         rd[i].flags = 0;
1054         rd[i].data = address;
1055         break;
1056       case AF_INET6:
1057         rd[i].record_type = GNUNET_DNSPARSER_TYPE_AAAA;
1058         rd[i].expiration_time = GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT).abs_value_us;
1059         rd[i].flags = 0;
1060         rd[i].data = address;
1061         rd[i].data_size = sizeof (struct in6_addr);
1062         break;
1063       default:
1064         GNUNET_assert (0);
1065       }
1066       break;
1067     }
1068   }
1069   GNUNET_assert (i < vpn_ctx->rd_count);
1070   handle_gns_resolution_result (rh,
1071                                 vpn_ctx->rd_count,
1072                                 rd);
1073   GNUNET_free (vpn_ctx->rd_data);
1074   GNUNET_free (vpn_ctx);
1075 }
1076
1077
1078 /**
1079  * Process a records that were decrypted from a block.
1080  *
1081  * @param cls closure with the 'struct GNS_ResolverHandle'
1082  * @param rd_count number of entries in @a rd array
1083  * @param rd array of records with data to store
1084  */
1085 static void
1086 handle_gns_resolution_result (void *cls,
1087                               unsigned int rd_count,
1088                               const struct GNUNET_NAMESTORE_RecordData *rd)
1089 {
1090   struct GNS_ResolverHandle *rh = cls;
1091   struct AuthorityChain *ac;
1092   unsigned int i;
1093   unsigned int j;
1094   struct sockaddr *sa;
1095   struct sockaddr_in v4;
1096   struct sockaddr_in6 v6;
1097   size_t sa_len;
1098   char *cname;
1099   struct VpnContext *vpn_ctx;
1100   const struct GNUNET_TUN_GnsVpnRecord *vpn;
1101   const char *vname;
1102   struct GNUNET_HashCode vhash;
1103   int af;
1104   char scratch[UINT16_MAX];
1105   size_t scratch_off;
1106   size_t scratch_start;
1107   size_t off;
1108   struct GNUNET_NAMESTORE_RecordData rd_new[rd_count];
1109   unsigned int rd_off;
1110
1111   if (0 == rh->name_resolution_pos)
1112   {
1113     /* top-level match, are we done yet? */
1114     if ( (rd_count > 0) &&
1115          (GNUNET_DNSPARSER_TYPE_CNAME == rd[0].record_type) &&
1116          (GNUNET_DNSPARSER_TYPE_CNAME != rh->record_type) )
1117     {
1118       cname = GNUNET_strndup (rd[0].data,
1119                               rd[0].data_size);
1120       handle_gns_cname_result (rh,
1121                                cname);
1122       GNUNET_free (cname);
1123       return;
1124     }
1125     /* If A/AAAA was requested, but we got a VPN
1126        record, we convert it to A/AAAA using GNUnet VPN */
1127     if ( (GNUNET_DNSPARSER_TYPE_A == rh->record_type) ||
1128          (GNUNET_DNSPARSER_TYPE_AAAA == rh->record_type) )
1129     {
1130       for (i=0;i<rd_count;i++)
1131       {
1132         if (GNUNET_NAMESTORE_TYPE_VPN == rd[i].record_type)
1133         {
1134           af = (GNUNET_DNSPARSER_TYPE_A == rh->record_type) ? AF_INET : AF_INET6;
1135           if (sizeof (struct GNUNET_TUN_GnsVpnRecord) <
1136               rd[i].data_size)
1137           {
1138             GNUNET_break_op (0);
1139             rh->proc (rh->proc_cls, 0, NULL);
1140             GNS_resolver_lookup_cancel (rh);
1141             return;
1142           }
1143           vpn = (const struct GNUNET_TUN_GnsVpnRecord *) rd[i].data;
1144           vname = (const char *) &vpn[1];
1145           if ('\0' != vname[rd[i].data_size - 1 - sizeof (struct GNUNET_TUN_GnsVpnRecord)])
1146           {
1147             GNUNET_break_op (0);
1148             rh->proc (rh->proc_cls, 0, NULL);
1149             GNS_resolver_lookup_cancel (rh);
1150             return;
1151           }
1152           GNUNET_CRYPTO_hash (vname,
1153                               strlen (vname), // FIXME: +1?
1154                               &vhash);
1155           vpn_ctx = GNUNET_new (struct VpnContext);
1156           rh->vpn_ctx = vpn_ctx;
1157           vpn_ctx->rh = rh;
1158           vpn_ctx->rd_data_size = GNUNET_NAMESTORE_records_get_size (rd_count,
1159                                                                      rd);
1160           vpn_ctx->rd_data = GNUNET_malloc (vpn_ctx->rd_data_size);
1161           (void) GNUNET_NAMESTORE_records_serialize (rd_count,
1162                                                      rd,
1163                                                      vpn_ctx->rd_data_size,
1164                                                      vpn_ctx->rd_data);
1165           vpn_ctx->vpn_request = GNUNET_VPN_redirect_to_peer (vpn_handle,
1166                                                               af,
1167                                                               ntohs (vpn->proto),
1168                                                               &vpn->peer,
1169                                                               &vhash,
1170                                                               GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT),
1171                                                               &vpn_allocation_cb,
1172                                                               rh);
1173           return;
1174         }
1175       }
1176     }
1177     /* convert relative names in record values to absolute names,
1178        using 'scratch' array for memory allocations */
1179     scratch_off = 0;
1180     rd_off = 0;
1181     for (i=0;i<rd_count;i++)
1182     {
1183       rd_new[rd_off] = rd[i];
1184       /* Check if the embedded name(s) end in "+", and if so,
1185          replace the "+" with the zone at "ac_tail", changing the name
1186          to a ".zkey".  The name is allocated on the 'scratch' array,
1187          so we can free it afterwards. */
1188       switch (rd[i].record_type)
1189       {
1190       case GNUNET_DNSPARSER_TYPE_CNAME:
1191         {
1192           char *cname;
1193
1194           off = 0;
1195           cname = GNUNET_DNSPARSER_parse_name (rd[i].data,
1196                                                rd[i].data_size,
1197                                                &off);
1198           if ( (NULL == cname) ||
1199                (off != rd[i].data_size) )
1200           {
1201             GNUNET_break_op (0); /* record not well-formed */
1202           }
1203           else
1204           {
1205             cname = translate_dot_plus (rh, cname);
1206             scratch_start = scratch_off;
1207             if (GNUNET_OK !=
1208                 GNUNET_DNSPARSER_builder_add_name (scratch,
1209                                                    sizeof (scratch),
1210                                                    &scratch_off,
1211                                                    cname))
1212             {
1213               GNUNET_break (0);
1214             }
1215             else
1216             {
1217               rd_new[rd_off].data = &scratch[scratch_start];
1218               rd_new[rd_off].data_size = scratch_off - scratch_start;
1219               rd_off++;
1220             }
1221           }
1222           GNUNET_free_non_null (cname);
1223         }
1224         break;
1225       case GNUNET_DNSPARSER_TYPE_SOA:
1226         {
1227           struct GNUNET_DNSPARSER_SoaRecord *soa;
1228
1229           off = 0;
1230           soa = GNUNET_DNSPARSER_parse_soa (rd[i].data,
1231                                             rd[i].data_size,
1232                                             &off);
1233           if ( (NULL == soa) ||
1234                (off != rd[i].data_size) )
1235           {
1236             GNUNET_break_op (0); /* record not well-formed */
1237           }
1238           else
1239           {
1240             soa->mname = translate_dot_plus (rh, soa->mname);
1241             soa->rname = translate_dot_plus (rh, soa->rname);
1242             scratch_start = scratch_off;
1243             if (GNUNET_OK !=
1244                 GNUNET_DNSPARSER_builder_add_soa (scratch,
1245                                                   sizeof (scratch),
1246                                                   &scratch_off,
1247                                                   soa))
1248             {
1249               GNUNET_break (0);
1250             }
1251             else
1252             {
1253               rd_new[rd_off].data = &scratch[scratch_start];
1254               rd_new[rd_off].data_size = scratch_off - scratch_start;
1255               rd_off++;
1256             }
1257           }
1258           if (NULL != soa)
1259             GNUNET_DNSPARSER_free_soa (soa);
1260         }
1261         break;
1262       case GNUNET_DNSPARSER_TYPE_MX:
1263         {
1264           struct GNUNET_DNSPARSER_MxRecord *mx;
1265
1266           off = 0;
1267           mx = GNUNET_DNSPARSER_parse_mx (rd[i].data,
1268                                           rd[i].data_size,
1269                                           &off);
1270           if ( (NULL == mx) ||
1271                (off != rd[i].data_size) )
1272           {
1273             GNUNET_break_op (0); /* record not well-formed */
1274           }
1275           else
1276           {
1277             mx->mxhost = translate_dot_plus (rh, mx->mxhost);
1278             scratch_start = scratch_off;
1279             if (GNUNET_OK !=
1280                 GNUNET_DNSPARSER_builder_add_mx (scratch,
1281                                                  sizeof (scratch),
1282                                                  &scratch_off,
1283                                                  mx))
1284             {
1285               GNUNET_break (0);
1286             }
1287             else
1288             {
1289               rd_new[rd_off].data = &scratch[scratch_start];
1290               rd_new[rd_off].data_size = scratch_off - scratch_start;
1291               rd_off++;
1292             }
1293           }
1294           if (NULL != mx)
1295             GNUNET_DNSPARSER_free_mx (mx);
1296         }
1297         break;
1298       case GNUNET_DNSPARSER_TYPE_SRV:
1299         {
1300           struct GNUNET_DNSPARSER_SrvRecord *srv;
1301
1302           off = 0;
1303           /* FIXME: passing rh->name here is is not necessarily what we want
1304              (SRV support not finished) */
1305           srv = GNUNET_DNSPARSER_parse_srv (rh->name,
1306                                             rd[i].data,
1307                                             rd[i].data_size,
1308                                             &off);
1309           if ( (NULL == srv) ||
1310                (off != rd[i].data_size) )
1311           {
1312             GNUNET_break_op (0); /* record not well-formed */
1313           }
1314           else
1315           {
1316             srv->domain_name = translate_dot_plus (rh, srv->domain_name);
1317             srv->target = translate_dot_plus (rh, srv->target);
1318             scratch_start = scratch_off;
1319             if (GNUNET_OK !=
1320                 GNUNET_DNSPARSER_builder_add_srv (scratch,
1321                                                   sizeof (scratch),
1322                                                   &scratch_off,
1323                                                   srv))
1324             {
1325               GNUNET_break (0);
1326             }
1327             else
1328             {
1329               rd_new[rd_off].data = &scratch[scratch_start];
1330               rd_new[rd_off].data_size = scratch_off - scratch_start;
1331               rd_off++;
1332             }
1333           }
1334           if (NULL != srv)
1335             GNUNET_DNSPARSER_free_srv (srv);
1336         }
1337         break;
1338       case GNUNET_NAMESTORE_TYPE_PKEY:
1339         /* tigger shortening */
1340         if (NULL != rh->shorten_key)
1341         {
1342           struct GNUNET_CRYPTO_EccPublicSignKey pub;
1343
1344           if (rd[i].data_size != sizeof (struct GNUNET_CRYPTO_EccPublicSignKey))
1345           {
1346             GNUNET_break_op (0);
1347             break;
1348           }
1349           memcpy (&pub, rd[i].data, rd[i].data_size);
1350           GNS_shorten_start (rh->ac_tail->label,
1351                              &pub,
1352                              rh->shorten_key);
1353         }
1354         rd_off++;
1355         break;
1356       default:
1357         rd_off++;
1358         break;
1359       }
1360     }
1361
1362     /* yes, we are done, return result */
1363     rh->proc (rh->proc_cls, rd_off, rd_new);
1364     GNS_resolver_lookup_cancel (rh);
1365     return;
1366   }
1367   /* need to recurse, check if we can */
1368   for (i=0;i<rd_count;i++)
1369   {
1370     switch (rd[i].record_type)
1371     {
1372     case GNUNET_NAMESTORE_TYPE_PKEY:
1373       /* delegation to another zone */
1374       if (sizeof (struct GNUNET_CRYPTO_EccPublicSignKey) !=
1375           rd[i].data_size)
1376       {
1377         GNUNET_break_op (0);
1378         rh->proc (rh->proc_cls, 0, NULL);
1379         GNS_resolver_lookup_cancel (rh);
1380         return;
1381       }
1382       /* expand authority chain */
1383       ac = GNUNET_new (struct AuthorityChain);
1384       ac->rh = rh;
1385       ac->gns_authority = GNUNET_YES;
1386       memcpy (&ac->authority_info.gns_authority,
1387               rd[i].data,
1388               sizeof (struct GNUNET_CRYPTO_EccPublicSignKey));
1389       ac->label = resolver_lookup_get_next_label (rh);
1390       /* tigger shortening */
1391       if (NULL != rh->shorten_key)
1392         GNS_shorten_start (rh->ac_tail->label,
1393                            &ac->authority_info.gns_authority,
1394                            rh->shorten_key);
1395       /* add AC to tail */
1396       GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1397                                         rh->ac_tail,
1398                                         ac);
1399       /* recurse */
1400       rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1401                                               rh);
1402       return;
1403     case GNUNET_DNSPARSER_TYPE_NS:
1404       /* resolution continues within DNS */
1405       if (GNUNET_DNSPARSER_MAX_NAME_LENGTH < rd[i].data_size)
1406       {
1407         GNUNET_break_op (0);
1408         rh->proc (rh->proc_cls, 0, NULL);
1409         GNS_resolver_lookup_cancel (rh);
1410         return;
1411       }
1412       /* find associated A/AAAA record */
1413       sa = NULL;
1414       sa_len = 0;
1415       for (j=0;j<rd_count;j++)
1416       {
1417         switch (rd[j].record_type)
1418         {
1419         case GNUNET_DNSPARSER_TYPE_A:
1420           if (sizeof (struct in_addr) != rd[i].data_size)
1421           {
1422             GNUNET_break_op (0);
1423             rh->proc (rh->proc_cls, 0, NULL);
1424             GNS_resolver_lookup_cancel (rh);
1425             return;
1426           }
1427           /* FIXME: might want to check if we support IPv4 here,
1428              and otherwise skip this one and hope we find another */
1429           memset (&v4, 0, sizeof (v4));
1430           sa_len = sizeof (v4);
1431           v4.sin_family = AF_INET;
1432           v4.sin_port = htons (53);
1433 #if HAVE_SOCKADDR_IN_SIN_LEN
1434           v4.sin_len = (u_char) sa_len;
1435 #endif
1436           memcpy (&v4.sin_addr,
1437                   rd[j].data,
1438                   sizeof (struct in_addr));
1439           sa = (struct sockaddr *) &v4;
1440           break;
1441         case GNUNET_DNSPARSER_TYPE_AAAA:
1442           if (sizeof (struct in6_addr) != rd[i].data_size)
1443           {
1444             GNUNET_break_op (0);
1445             rh->proc (rh->proc_cls, 0, NULL);
1446             GNS_resolver_lookup_cancel (rh);
1447             return;
1448           }
1449           /* FIXME: might want to check if we support IPv6 here,
1450              and otherwise skip this one and hope we find another */
1451           memset (&v6, 0, sizeof (v6));
1452           sa_len = sizeof (v6);
1453           v6.sin6_family = AF_INET6;
1454           v6.sin6_port = htons (53);
1455 #if HAVE_SOCKADDR_IN_SIN_LEN
1456           v6.sin6_len = (u_char) sa_len;
1457 #endif
1458           memcpy (&v6.sin6_addr,
1459                   rd[j].data,
1460                   sizeof (struct in6_addr));
1461           sa = (struct sockaddr *) &v6;
1462           break;
1463         default:
1464           break;
1465         }
1466         if (NULL != sa)
1467           break;
1468       }
1469       if (NULL == sa)
1470       {
1471         /* we cannot continue; NS without A/AAAA */
1472         rh->proc (rh->proc_cls, 0, NULL);
1473         GNS_resolver_lookup_cancel (rh);
1474         return;
1475       }
1476       /* expand authority chain */
1477       ac = GNUNET_new (struct AuthorityChain);
1478       ac->rh = rh;
1479       strncpy (ac->authority_info.dns_authority.name,
1480                rd[i].data,
1481                rd[i].data_size);
1482       ac->authority_info.dns_authority.name[rd[i].data_size] = '\0';
1483       memcpy (&ac->authority_info.dns_authority.dns_ip,
1484               sa,
1485               sa_len);
1486       /* for DNS recursion, the label is the full DNS name,
1487          created from the remainder of the GNS name and the
1488          name in the NS record */
1489       GNUNET_asprintf (&ac->label,
1490                        "%.*s%s",
1491                        (int) rh->name_resolution_pos,
1492                        rh->name,
1493                        ac->authority_info.dns_authority.name);
1494       GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1495                                         rh->ac_tail,
1496                                         ac);
1497       if (strlen (ac->label) > GNUNET_DNSPARSER_MAX_NAME_LENGTH)
1498       {
1499         GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1500                     _("GNS lookup resulted in DNS name that is too long (`%s')\n"),
1501                     ac->label);
1502         rh->proc (rh->proc_cls, 0, NULL);
1503         GNS_resolver_lookup_cancel (rh);
1504         return;
1505       }
1506       /* recurse */
1507       rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1508                                               rh);
1509       return;
1510     case GNUNET_DNSPARSER_TYPE_CNAME:
1511       cname = GNUNET_strndup (rd[i].data,
1512                               rd[i].data_size);
1513       handle_gns_cname_result (rh,
1514                                cname);
1515       GNUNET_free (cname);
1516       return;
1517       /* FIXME: handle DNAME */
1518     default:
1519       /* skip */
1520       break;
1521     }
1522   }
1523   GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1524               _("GNS lookup recursion failed (no delegation record found)\n"));
1525   rh->proc (rh->proc_cls, 0, NULL);
1526   GNS_resolver_lookup_cancel (rh);
1527 }
1528
1529
1530 /**
1531  * Function called once the namestore has completed the request for
1532  * caching a block.
1533  *
1534  * @param cls closure with the 'struct GNS_ResolverHandle'
1535  * @param success #GNUNET_OK on success
1536  * @param emsg error message
1537  */
1538 static void
1539 namestore_cache_continuation (void *cls,
1540                               int32_t success,
1541                               const char *emsg)
1542 {
1543   struct GNS_ResolverHandle *rh = cls;
1544
1545   rh->namestore_qe = NULL;
1546   if (NULL != emsg)
1547     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1548                 _("Failed to cache GNS resolution: %s\n"),
1549                 emsg);
1550 }
1551
1552
1553 /**
1554  * Iterator called on each result obtained for a DHT
1555  * operation that expects a reply
1556  *
1557  * @param cls closure with the `struct GNS_ResolverHandle`
1558  * @param exp when will this value expire
1559  * @param key key of the result
1560  * @param get_path peers on reply path (or NULL if not recorded)
1561  *                 [0] = datastore's first neighbor, [length - 1] = local peer
1562  * @param get_path_length number of entries in @a get_path
1563  * @param put_path peers on the PUT path (or NULL if not recorded)
1564  *                 [0] = origin, [length - 1] = datastore
1565  * @param put_path_length number of entries in @a get_path
1566  * @param type type of the result
1567  * @param size number of bytes in data
1568  * @param data pointer to the result data
1569  */
1570 static void
1571 handle_dht_response (void *cls,
1572                      struct GNUNET_TIME_Absolute exp,
1573                      const struct GNUNET_HashCode *key,
1574                      const struct GNUNET_PeerIdentity *get_path,
1575                      unsigned int get_path_length,
1576                      const struct GNUNET_PeerIdentity *put_path,
1577                      unsigned int put_path_length,
1578                      enum GNUNET_BLOCK_Type type,
1579                      size_t size, const void *data)
1580 {
1581   struct GNS_ResolverHandle *rh = cls;
1582   struct AuthorityChain *ac = rh->ac_tail;
1583   const struct GNUNET_NAMESTORE_Block *block;
1584
1585   GNUNET_DHT_get_stop (rh->get_handle);
1586   rh->get_handle = NULL;
1587   GNUNET_CONTAINER_heap_remove_node (rh->dht_heap_node);
1588   rh->dht_heap_node = NULL;
1589   if (size < sizeof (struct GNUNET_NAMESTORE_Block))
1590   {
1591     /* how did this pass DHT block validation!? */
1592     GNUNET_break (0);
1593     rh->proc (rh->proc_cls, 0, NULL);
1594     GNS_resolver_lookup_cancel (rh);
1595     return;
1596   }
1597   block = data;
1598   if (size !=
1599       ntohl (block->purpose.size) +
1600       sizeof (struct GNUNET_CRYPTO_EccPublicSignKey) +
1601       sizeof (struct GNUNET_CRYPTO_EccSignature))
1602   {
1603     /* how did this pass DHT block validation!? */
1604     GNUNET_break (0);
1605     rh->proc (rh->proc_cls, 0, NULL);
1606     GNS_resolver_lookup_cancel (rh);
1607     return;
1608   }
1609   if (GNUNET_OK !=
1610       GNUNET_NAMESTORE_block_decrypt (block,
1611                                       &ac->authority_info.gns_authority,
1612                                       ac->label,
1613                                       &handle_gns_resolution_result,
1614                                       rh))
1615   {
1616     GNUNET_break_op (0); /* block was ill-formed */
1617     rh->proc (rh->proc_cls, 0, NULL);
1618     GNS_resolver_lookup_cancel (rh);
1619     return;
1620   }
1621   /* Cache well-formed blocks */
1622   rh->namestore_qe = GNUNET_NAMESTORE_block_cache (namestore_handle,
1623                                                    block,
1624                                                    &namestore_cache_continuation,
1625                                                    rh);
1626 }
1627
1628
1629 /**
1630  * Process a record that was stored in the namestore.
1631  *
1632  * @param cls closure with the `struct GNS_ResolverHandle`
1633  * @param block block that was stored in the namestore
1634  */
1635 static void
1636 handle_namestore_block_response (void *cls,
1637                                  const struct GNUNET_NAMESTORE_Block *block)
1638 {
1639   struct GNS_ResolverHandle *rh = cls;
1640   struct GNS_ResolverHandle *rx;
1641   struct AuthorityChain *ac = rh->ac_tail;
1642   const char *label = ac->label;
1643   const struct GNUNET_CRYPTO_EccPublicSignKey *auth = &ac->authority_info.gns_authority;
1644   struct GNUNET_HashCode query;
1645
1646   GNUNET_NAMESTORE_query_from_public_key (auth,
1647                                           label,
1648                                           &query);
1649   rh->namestore_qe = NULL;
1650   if ( (GNUNET_NO == rh->only_cached) &&
1651        ( (NULL == block) ||
1652          (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us) ) )
1653   {
1654     /* Namestore knows nothing; try DHT lookup */
1655     rh->get_handle = GNUNET_DHT_get_start (dht_handle,
1656                                            GNUNET_BLOCK_TYPE_GNS_NAMERECORD,
1657                                            &query,
1658                                            DHT_GNS_REPLICATION_LEVEL,
1659                                            GNUNET_DHT_RO_DEMULTIPLEX_EVERYWHERE,
1660                                            NULL, 0,
1661                                            &handle_dht_response, rh);
1662     rh->dht_heap_node = GNUNET_CONTAINER_heap_insert (dht_lookup_heap,
1663                                                       rh,
1664                                                       GNUNET_TIME_absolute_get ().abs_value_us);
1665     if (GNUNET_CONTAINER_heap_get_size (dht_lookup_heap) > max_allowed_background_queries)
1666     {
1667       /* fail longest-standing DHT request */
1668       rx = GNUNET_CONTAINER_heap_peek (dht_lookup_heap);
1669       GNUNET_assert (NULL != rx);
1670       rx->proc (rx->proc_cls, 0, NULL);
1671       GNS_resolver_lookup_cancel (rx);
1672     }
1673     return;
1674   }
1675   if ( (NULL == block) ||
1676        (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us) )
1677   {
1678     /* DHT not permitted and no local result, fail */
1679     rh->proc (rh->proc_cls, 0, NULL);
1680     GNS_resolver_lookup_cancel (rh);
1681     return;
1682   }
1683   if (GNUNET_OK !=
1684       GNUNET_NAMESTORE_block_decrypt (block,
1685                                       auth,
1686                                       label,
1687                                       &handle_gns_resolution_result,
1688                                       rh))
1689   {
1690     GNUNET_break_op (0); /* block was ill-formed */
1691     rh->proc (rh->proc_cls, 0, NULL);
1692     GNS_resolver_lookup_cancel (rh);
1693     return;
1694   }
1695 }
1696
1697
1698 /**
1699  * Lookup tail of our authority chain in the namestore.
1700  *
1701  * @param rh query we are processing
1702  */
1703 static void
1704 recursive_gns_resolution_namestore (struct GNS_ResolverHandle *rh)
1705 {
1706   struct AuthorityChain *ac = rh->ac_tail;
1707   struct GNUNET_HashCode query;
1708
1709   GNUNET_NAMESTORE_query_from_public_key (&ac->authority_info.gns_authority,
1710                                           ac->label,
1711                                           &query);
1712   rh->namestore_qe = GNUNET_NAMESTORE_lookup_block (namestore_handle,
1713                                                     &query,
1714                                                     &handle_namestore_block_response,
1715                                                     rh);
1716 }
1717
1718
1719 /**
1720  * Task scheduled to continue with the resolution process.
1721  *
1722  * @param cls the `struct GNS_ResolverHandle` of the resolution
1723  * @param tc task context
1724  */
1725 static void
1726 recursive_resolution (void *cls,
1727                       const struct GNUNET_SCHEDULER_TaskContext *tc)
1728 {
1729   struct GNS_ResolverHandle *rh = cls;
1730
1731   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
1732   if (MAX_RECURSION < rh->loop_limiter++)
1733   {
1734     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1735                 "Encountered unbounded recursion resolving `%s'\n",
1736                 rh->name);
1737     rh->proc (rh->proc_cls, 0, NULL);
1738     GNS_resolver_lookup_cancel (rh);
1739     return;
1740   }
1741   if (GNUNET_YES == rh->ac_tail->gns_authority)
1742     recursive_gns_resolution_namestore (rh);
1743   else
1744     recursive_dns_resolution (rh);
1745 }
1746
1747
1748 /**
1749  * Begin the resolution process from 'name', starting with
1750  * the identification of the zone specified by 'name'.
1751  *
1752  * @param rh resolution to perform
1753  */
1754 static void
1755 start_resolver_lookup (struct GNS_ResolverHandle *rh)
1756 {
1757   struct AuthorityChain *ac;
1758   char *x;
1759   char *y;
1760   char *pkey;
1761
1762   if ( ( (GNUNET_YES == is_canonical (rh->name)) &&
1763          (0 != strcmp (GNUNET_GNS_TLD, rh->name)) ) ||
1764        ( (GNUNET_YES != is_gnu_tld (rh->name)) &&
1765          (GNUNET_YES != is_zkey_tld (rh->name)) ) )
1766   {
1767     /* use standard DNS lookup */
1768     int af;
1769
1770     switch (rh->record_type)
1771     {
1772     case GNUNET_DNSPARSER_TYPE_A:
1773       af = AF_INET;
1774       break;
1775     case GNUNET_DNSPARSER_TYPE_AAAA:
1776       af = AF_INET6;
1777       break;
1778     default:
1779       af = AF_UNSPEC;
1780       break;
1781     }
1782     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1783                 "Doing standard DNS lookup for `%s'\n",
1784                 rh->name);
1785     rh->std_resolve = GNUNET_RESOLVER_ip_get (rh->name,
1786                                               af,
1787                                               DNS_LOOKUP_TIMEOUT,
1788                                               &handle_dns_result,
1789                                               rh);
1790     return;
1791   }
1792   if (is_zkey_tld (rh->name))
1793   {
1794     /* Name ends with ".zkey", try to replace authority zone with zkey
1795        authority */
1796     GNUNET_free (resolver_lookup_get_next_label (rh)); /* will return "zkey" */
1797     x = resolver_lookup_get_next_label (rh); /* will return 'x' coordinate */
1798     y = resolver_lookup_get_next_label (rh); /* will return 'y' coordinate */
1799     GNUNET_asprintf (&pkey,
1800                      "%s%s",
1801                      x, y);
1802     if ( (NULL == x) ||
1803          (NULL == y) ||
1804          (GNUNET_OK !=
1805           GNUNET_CRYPTO_ecc_public_sign_key_from_string (pkey,
1806                                                     strlen (pkey),
1807                                                     &rh->authority_zone)) )
1808     {
1809       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1810                   _("Hostname `%s' is not well-formed, resolution fails\n"),
1811                   rh->name);
1812       rh->task_id = GNUNET_SCHEDULER_add_now (&fail_resolution, rh);
1813     }
1814     GNUNET_free_non_null (x);
1815     GNUNET_free_non_null (y);
1816     GNUNET_free (pkey);
1817   }
1818   else
1819   {
1820     /* Name ends with ".gnu", eat ".gnu" and continue with resolution */
1821     GNUNET_free (resolver_lookup_get_next_label (rh));
1822   }
1823   ac = GNUNET_new (struct AuthorityChain);
1824   ac->rh = rh;
1825   ac->label = resolver_lookup_get_next_label (rh);
1826   if (NULL == ac->label)
1827     /* name was just "gnu", so we default to label '+' */
1828     ac->label = GNUNET_strdup (GNUNET_GNS_MASTERZONE_STR);
1829   ac->gns_authority = GNUNET_YES;
1830   ac->authority_info.gns_authority = rh->authority_zone;
1831   GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1832                                     rh->ac_tail,
1833                                     ac);
1834   rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1835                                           rh);
1836 }
1837
1838
1839 /**
1840  * Lookup of a record in a specific zone calls lookup result processor
1841  * on result.
1842  *
1843  * @param zone the zone to perform the lookup in
1844  * @param record_type the record type to look up
1845  * @param name the name to look up
1846  * @param shorten_key a private key for use with PSEU import (can be NULL)
1847  * @param only_cached #GNUNET_NO to only check locally not DHT for performance
1848  * @param proc the processor to call on result
1849  * @param proc_cls the closure to pass to @a proc
1850  * @return handle to cancel operation
1851  */
1852 struct GNS_ResolverHandle *
1853 GNS_resolver_lookup (const struct GNUNET_CRYPTO_EccPublicSignKey *zone,
1854                      uint32_t record_type,
1855                      const char *name,
1856                      const struct GNUNET_CRYPTO_EccPrivateKey *shorten_key,
1857                      int only_cached,
1858                      GNS_ResultProcessor proc, void *proc_cls)
1859 {
1860   struct GNS_ResolverHandle *rh;
1861
1862   rh = GNUNET_new (struct GNS_ResolverHandle);
1863   GNUNET_CONTAINER_DLL_insert (rlh_head,
1864                                rlh_tail,
1865                                rh);
1866   rh->authority_zone = *zone;
1867   rh->proc = proc;
1868   rh->proc_cls = proc_cls;
1869   rh->only_cached = only_cached;
1870   rh->record_type = record_type;
1871   rh->name = GNUNET_strdup (name);
1872   rh->name_resolution_pos = strlen (name);
1873   if (NULL != shorten_key)
1874   {
1875     rh->shorten_key = GNUNET_new (struct GNUNET_CRYPTO_EccPrivateKey);
1876     *rh->shorten_key = *shorten_key;
1877   }
1878   start_resolver_lookup (rh);
1879   return rh;
1880 }
1881
1882
1883 /**
1884  * Cancel active resolution (i.e. client disconnected).
1885  *
1886  * @param rh resolution to abort
1887  */
1888 void
1889 GNS_resolver_lookup_cancel (struct GNS_ResolverHandle *rh)
1890 {
1891   struct DnsResult *dr;
1892   struct AuthorityChain *ac;
1893   struct VpnContext *vpn_ctx;
1894
1895   GNUNET_CONTAINER_DLL_remove (rlh_head,
1896                                rlh_tail,
1897                                rh);
1898   while (NULL != (ac = rh->ac_head))
1899   {
1900     GNUNET_CONTAINER_DLL_remove (rh->ac_head,
1901                                  rh->ac_tail,
1902                                  ac);
1903     GNUNET_free (ac->label);
1904     GNUNET_free (ac);
1905   }
1906   if (GNUNET_SCHEDULER_NO_TASK != rh->task_id)
1907   {
1908     GNUNET_SCHEDULER_cancel (rh->task_id);
1909     rh->task_id = GNUNET_SCHEDULER_NO_TASK;
1910   }
1911   if (NULL != rh->get_handle)
1912   {
1913     GNUNET_DHT_get_stop (rh->get_handle);
1914     rh->get_handle = NULL;
1915   }
1916   if (NULL != rh->dht_heap_node)
1917   {
1918     GNUNET_CONTAINER_heap_remove_node (rh->dht_heap_node);
1919     rh->dht_heap_node = NULL;
1920   }
1921   if (NULL != (vpn_ctx = rh->vpn_ctx))
1922   {
1923     GNUNET_VPN_cancel_request (vpn_ctx->vpn_request);
1924     GNUNET_free (vpn_ctx->rd_data);
1925     GNUNET_free (vpn_ctx);
1926   }
1927   if (NULL != rh->dns_request)
1928   {
1929     GNUNET_DNSSTUB_resolve_cancel (rh->dns_request);
1930     rh->dns_request = NULL;
1931   }
1932   if (NULL != rh->namestore_qe)
1933   {
1934     GNUNET_NAMESTORE_cancel (rh->namestore_qe);
1935     rh->namestore_qe = NULL;
1936   }
1937   if (NULL != rh->std_resolve)
1938   {
1939     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1940                 "Canceling standard DNS resolution\n");
1941     GNUNET_RESOLVER_request_cancel (rh->std_resolve);
1942     rh->std_resolve = NULL;
1943   }
1944   while (NULL != (dr = rh->dns_result_head))
1945   {
1946     GNUNET_CONTAINER_DLL_remove (rh->dns_result_head,
1947                                  rh->dns_result_tail,
1948                                  dr);
1949     GNUNET_free (dr);
1950   }
1951   GNUNET_free_non_null (rh->shorten_key);
1952   GNUNET_free (rh->name);
1953   GNUNET_free (rh);
1954 }
1955
1956
1957 /* ***************** Resolver initialization ********************* */
1958
1959
1960 /**
1961  * Initialize the resolver
1962  *
1963  * @param nh the namestore handle
1964  * @param dht the dht handle
1965  * @param c configuration handle
1966  * @param max_bg_queries maximum number of parallel background queries in dht
1967  */
1968 void
1969 GNS_resolver_init (struct GNUNET_NAMESTORE_Handle *nh,
1970                    struct GNUNET_DHT_Handle *dht,
1971                    const struct GNUNET_CONFIGURATION_Handle *c,
1972                    unsigned long long max_bg_queries)
1973 {
1974   char *dns_ip;
1975
1976   cfg = c;
1977   namestore_handle = nh;
1978   dht_handle = dht;
1979   dht_lookup_heap =
1980     GNUNET_CONTAINER_heap_create (GNUNET_CONTAINER_HEAP_ORDER_MIN);
1981   max_allowed_background_queries = max_bg_queries;
1982   if (GNUNET_OK !=
1983       GNUNET_CONFIGURATION_get_value_string (c,
1984                                              "gns",
1985                                              "DNS_RESOLVER",
1986                                              &dns_ip))
1987   {
1988     /* user did not specify DNS resolver, use 8.8.8.8 */
1989     dns_ip = GNUNET_strdup ("8.8.8.8");
1990   }
1991   dns_handle = GNUNET_DNSSTUB_start (dns_ip);
1992   GNUNET_free (dns_ip);
1993   vpn_handle = GNUNET_VPN_connect (cfg);
1994 }
1995
1996
1997 /**
1998  * Shutdown resolver
1999  */
2000 void
2001 GNS_resolver_done ()
2002 {
2003   struct GNS_ResolverHandle *rh;
2004
2005   /* abort active resolutions */
2006   while (NULL != (rh = rlh_head))
2007   {
2008     rh->proc (rh->proc_cls, 0, NULL);
2009     GNS_resolver_lookup_cancel (rh);
2010   }
2011   GNUNET_CONTAINER_heap_destroy (dht_lookup_heap);
2012   dht_lookup_heap = NULL;
2013   GNUNET_DNSSTUB_stop (dns_handle);
2014   dns_handle = NULL;
2015   GNUNET_VPN_disconnect (vpn_handle);
2016   vpn_handle = NULL;
2017   dht_handle = NULL;
2018   namestore_handle = NULL;
2019 }
2020
2021
2022 /* *************** common helper functions (do not really belong here) *********** */
2023
2024 /**
2025  * Checks if @a name ends in ".TLD"
2026  *
2027  * @param name the name to check
2028  * @param tld the TLD to check for
2029  * @return GNUNET_YES or GNUNET_NO
2030  */
2031 int
2032 is_tld (const char* name, const char* tld)
2033 {
2034   size_t offset = 0;
2035
2036   if (strlen (name) <= strlen (tld))
2037     return GNUNET_NO;
2038   offset = strlen (name) - strlen (tld);
2039   if (0 != strcmp (name + offset, tld))
2040     return GNUNET_NO;
2041   return GNUNET_YES;
2042 }
2043
2044
2045 /* end of gnunet-service-gns_resolver.c */