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
 950   nlen = strlen (cname);
 951   if ( (nlen > 2) &&
 952        (0 == strcmp (".+",
 953                      &cname[nlen - 2])) )
 954   {
 955     /* CNAME resolution continues relative to current domain */
 956     if (0 == rh->name_resolution_pos)
 957     {
 958       res = GNUNET_strndup (cname, nlen - 2);
 959       rh->name_resolution_pos = nlen - 2;
 960     }
 961     else
 962     {
 963       GNUNET_asprintf (&res,
 964                        "%.*s.%.*s",
 965                        (int) rh->name_resolution_pos,
 966                        rh->name,
 967                        (int) (nlen - 2),
 968                        cname);
 969       rh->name_resolution_pos = strlen (res);
 970     }
 971     GNUNET_free (rh->name);
 972     rh->name = res;
 973     rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
 974                                             rh);
 975     return;
 976   }
 977   /* name is absolute, start from the beginning */
 978   GNUNET_free (rh->name);
 979   rh->name = GNUNET_strdup (cname);
 980   start_resolver_lookup (rh);
 981 }
 982
 983
 984 /**
 985  * Process a records that were decrypted from a block.
 986  *
 987  * @param cls closure with the 'struct GNS_ResolverHandle'
 988  * @param rd_count number of entries in @a rd array
 989  * @param rd array of records with data to store
 990  */
 991 static void
 992 handle_gns_resolution_result (void *cls,
 993                               unsigned int rd_count,
 994                               const struct GNUNET_NAMESTORE_RecordData *rd);
 995
 996
 997 /**
 998  * Callback invoked from the VPN service once a redirection is
 999  * available.  Provides the IP address that can now be used to
1000  * reach the requested destination.  Replaces the "VPN" record
1001  * with the respective A/AAAA record and continues processing.
1002  *
1003  * @param cls closure
1004  * @param af address family, AF_INET or AF_INET6; AF_UNSPEC on error;
1005  *                will match 'result_af' from the request
1006  * @param address IP address (struct in_addr or struct in_addr6, depending on 'af')
1007  *                that the VPN allocated for the redirection;
1008  *                traffic to this IP will now be redirected to the
1009  *                specified target peer; NULL on error
1010  */
1011 static void
1012 vpn_allocation_cb (void *cls,
1013                    int af,
1014                    const void *address)
1015 {
1016   struct VpnContext *vpn_ctx = cls;
1017   struct GNS_ResolverHandle *rh = vpn_ctx->rh;
1018   struct GNUNET_NAMESTORE_RecordData rd[vpn_ctx->rd_count];
1019   unsigned int i;
1020
1021   vpn_ctx->vpn_request = NULL;
1022   rh->vpn_ctx = NULL;
1023   GNUNET_assert (GNUNET_OK ==
1024                  GNUNET_NAMESTORE_records_deserialize (vpn_ctx->rd_data_size,
1025                                                        vpn_ctx->rd_data,
1026                                                        vpn_ctx->rd_count,
1027                                                        rd));
1028   for (i=0;i<vpn_ctx->rd_count;i++)
1029   {
1030     if (GNUNET_NAMESTORE_TYPE_VPN == rd[i].record_type)
1031     {
1032       switch (af)
1033       {
1034       case AF_INET:
1035         rd[i].record_type = GNUNET_DNSPARSER_TYPE_A;
1036         rd[i].data_size = sizeof (struct in_addr);
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         break;
1041       case AF_INET6:
1042         rd[i].record_type = GNUNET_DNSPARSER_TYPE_AAAA;
1043         rd[i].expiration_time = GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT).abs_value_us;
1044         rd[i].flags = 0;
1045         rd[i].data = address;
1046         rd[i].data_size = sizeof (struct in6_addr);
1047         break;
1048       default:
1049         GNUNET_assert (0);
1050       }
1051       break;
1052     }
1053   }
1054   GNUNET_assert (i < vpn_ctx->rd_count);
1055   handle_gns_resolution_result (rh,
1056                                 vpn_ctx->rd_count,
1057                                 rd);
1058   GNUNET_free (vpn_ctx->rd_data);
1059   GNUNET_free (vpn_ctx);
1060 }
1061
1062
1063 /**
1064  * Process a records that were decrypted from a block.
1065  *
1066  * @param cls closure with the 'struct GNS_ResolverHandle'
1067  * @param rd_count number of entries in @a rd array
1068  * @param rd array of records with data to store
1069  */
1070 static void
1071 handle_gns_resolution_result (void *cls,
1072                               unsigned int rd_count,
1073                               const struct GNUNET_NAMESTORE_RecordData *rd)
1074 {
1075   struct GNS_ResolverHandle *rh = cls;
1076   struct AuthorityChain *ac;
1077   unsigned int i;
1078   unsigned int j;
1079   struct sockaddr *sa;
1080   struct sockaddr_in v4;
1081   struct sockaddr_in6 v6;
1082   size_t sa_len;
1083   char *cname;
1084   struct VpnContext *vpn_ctx;
1085   const struct GNUNET_TUN_GnsVpnRecord *vpn;
1086   const char *vname;
1087   struct GNUNET_HashCode vhash;
1088   int af;
1089   char scratch[UINT16_MAX];
1090   size_t scratch_off;
1091   size_t scratch_start;
1092   size_t off;
1093   struct GNUNET_NAMESTORE_RecordData rd_new[rd_count];
1094   unsigned int rd_off;
1095
1096   if (0 == rh->name_resolution_pos)
1097   {
1098     /* top-level match, are we done yet? */
1099     if ( (rd_count > 0) &&
1100          (GNUNET_DNSPARSER_TYPE_CNAME == rd[0].record_type) &&
1101          (GNUNET_DNSPARSER_TYPE_CNAME != rh->record_type) )
1102     {
1103       cname = GNUNET_strndup (rd[0].data,
1104                               rd[0].data_size);
1105       handle_gns_cname_result (rh,
1106                                cname);
1107       GNUNET_free (cname);
1108       return;
1109     }
1110     /* If A/AAAA was requested, but we got a VPN
1111        record, we convert it to A/AAAA using GNUnet VPN */
1112     if ( (GNUNET_DNSPARSER_TYPE_A == rh->record_type) ||
1113          (GNUNET_DNSPARSER_TYPE_AAAA == rh->record_type) )
1114     {
1115       for (i=0;i<rd_count;i++)
1116       {
1117         if (GNUNET_NAMESTORE_TYPE_VPN == rd[i].record_type)
1118         {
1119           af = (GNUNET_DNSPARSER_TYPE_A == rh->record_type) ? AF_INET : AF_INET6;
1120           if (sizeof (struct GNUNET_TUN_GnsVpnRecord) <
1121               rd[i].data_size)
1122           {
1123             GNUNET_break_op (0);
1124             rh->proc (rh->proc_cls, 0, NULL);
1125             GNS_resolver_lookup_cancel (rh);
1126             return;
1127           }
1128           vpn = (const struct GNUNET_TUN_GnsVpnRecord *) rd[i].data;
1129           vname = (const char *) &vpn[1];
1130           if ('\0' != vname[rd[i].data_size - 1 - sizeof (struct GNUNET_TUN_GnsVpnRecord)])
1131           {
1132             GNUNET_break_op (0);
1133             rh->proc (rh->proc_cls, 0, NULL);
1134             GNS_resolver_lookup_cancel (rh);
1135             return;
1136           }
1137           GNUNET_CRYPTO_hash (vname,
1138                               strlen (vname), // FIXME: +1?
1139                               &vhash);
1140           vpn_ctx = GNUNET_new (struct VpnContext);
1141           rh->vpn_ctx = vpn_ctx;
1142           vpn_ctx->rh = rh;
1143           vpn_ctx->rd_data_size = GNUNET_NAMESTORE_records_get_size (rd_count,
1144                                                                      rd);
1145           vpn_ctx->rd_data = GNUNET_malloc (vpn_ctx->rd_data_size);
1146           (void) GNUNET_NAMESTORE_records_serialize (rd_count,
1147                                                      rd,
1148                                                      vpn_ctx->rd_data_size,
1149                                                      vpn_ctx->rd_data);
1150           vpn_ctx->vpn_request = GNUNET_VPN_redirect_to_peer (vpn_handle,
1151                                                               af,
1152                                                               ntohs (vpn->proto),
1153                                                               &vpn->peer,
1154                                                               &vhash,
1155                                                               GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT),
1156                                                               &vpn_allocation_cb,
1157                                                               rh);
1158           return;
1159         }
1160       }
1161     }
1162     /* convert relative names in record values to absolute names,
1163        using 'scratch' array for memory allocations */
1164     scratch_off = 0;
1165     rd_off = 0;
1166     for (i=0;i<rd_count;i++)
1167     {
1168       rd_new[rd_off] = rd[i];
1169       /* Check if the embedded name(s) end in "+", and if so,
1170          replace the "+" with the zone at "ac_tail", changing the name
1171          to a ".zkey".  The name is allocated on the 'scratch' array,
1172          so we can free it afterwards. */
1173       switch (rd[i].record_type)
1174       {
1175       case GNUNET_DNSPARSER_TYPE_CNAME:
1176         {
1177           char *cname;
1178
1179           off = 0;
1180           cname = GNUNET_DNSPARSER_parse_name (rd[i].data,
1181                                                rd[i].data_size,
1182                                                &off);
1183           if ( (NULL == cname) ||
1184                (off != rd[i].data_size) )
1185           {
1186             GNUNET_break_op (0); /* record not well-formed */
1187           }
1188           else
1189           {
1190             cname = translate_dot_plus (rh, cname);
1191             scratch_start = scratch_off;
1192             if (GNUNET_OK !=
1193                 GNUNET_DNSPARSER_builder_add_name (scratch,
1194                                                    sizeof (scratch),
1195                                                    &scratch_off,
1196                                                    cname))
1197             {
1198               GNUNET_break (0);
1199             }
1200             else
1201             {
1202               rd_new[rd_off].data = &scratch[scratch_start];
1203               rd_new[rd_off].data_size = scratch_off - scratch_start;
1204               rd_off++;
1205             }
1206           }
1207           GNUNET_free_non_null (cname);
1208         }
1209         break;
1210       case GNUNET_DNSPARSER_TYPE_SOA:
1211         {
1212           struct GNUNET_DNSPARSER_SoaRecord *soa;
1213
1214           off = 0;
1215           soa = GNUNET_DNSPARSER_parse_soa (rd[i].data,
1216                                             rd[i].data_size,
1217                                             &off);
1218           if ( (NULL == soa) ||
1219                (off != rd[i].data_size) )
1220           {
1221             GNUNET_break_op (0); /* record not well-formed */
1222           }
1223           else
1224           {
1225             soa->mname = translate_dot_plus (rh, soa->mname);
1226             soa->rname = translate_dot_plus (rh, soa->rname);
1227             scratch_start = scratch_off;
1228             if (GNUNET_OK !=
1229                 GNUNET_DNSPARSER_builder_add_soa (scratch,
1230                                                   sizeof (scratch),
1231                                                   &scratch_off,
1232                                                   soa))
1233             {
1234               GNUNET_break (0);
1235             }
1236             else
1237             {
1238               rd_new[rd_off].data = &scratch[scratch_start];
1239               rd_new[rd_off].data_size = scratch_off - scratch_start;
1240               rd_off++;
1241             }
1242           }
1243           if (NULL != soa)
1244             GNUNET_DNSPARSER_free_soa (soa);
1245         }
1246         break;
1247       case GNUNET_DNSPARSER_TYPE_MX:
1248         {
1249           struct GNUNET_DNSPARSER_MxRecord *mx;
1250
1251           off = 0;
1252           mx = GNUNET_DNSPARSER_parse_mx (rd[i].data,
1253                                           rd[i].data_size,
1254                                           &off);
1255           if ( (NULL == mx) ||
1256                (off != rd[i].data_size) )
1257           {
1258             GNUNET_break_op (0); /* record not well-formed */
1259           }
1260           else
1261           {
1262             mx->mxhost = translate_dot_plus (rh, mx->mxhost);
1263             scratch_start = scratch_off;
1264             if (GNUNET_OK !=
1265                 GNUNET_DNSPARSER_builder_add_mx (scratch,
1266                                                  sizeof (scratch),
1267                                                  &scratch_off,
1268                                                  mx))
1269             {
1270               GNUNET_break (0);
1271             }
1272             else
1273             {
1274               rd_new[rd_off].data = &scratch[scratch_start];
1275               rd_new[rd_off].data_size = scratch_off - scratch_start;
1276               rd_off++;
1277             }
1278           }
1279           if (NULL != mx)
1280             GNUNET_DNSPARSER_free_mx (mx);
1281         }
1282         break;
1283       case GNUNET_DNSPARSER_TYPE_SRV:
1284         {
1285           struct GNUNET_DNSPARSER_SrvRecord *srv;
1286
1287           off = 0;
1288           /* FIXME: passing rh->name here is is not necessarily what we want
1289              (SRV support not finished) */
1290           srv = GNUNET_DNSPARSER_parse_srv (rh->name,
1291                                             rd[i].data,
1292                                             rd[i].data_size,
1293                                             &off);
1294           if ( (NULL == srv) ||
1295                (off != rd[i].data_size) )
1296           {
1297             GNUNET_break_op (0); /* record not well-formed */
1298           }
1299           else
1300           {
1301             srv->domain_name = translate_dot_plus (rh, srv->domain_name);
1302             srv->target = translate_dot_plus (rh, srv->target);
1303             scratch_start = scratch_off;
1304             if (GNUNET_OK !=
1305                 GNUNET_DNSPARSER_builder_add_srv (scratch,
1306                                                   sizeof (scratch),
1307                                                   &scratch_off,
1308                                                   srv))
1309             {
1310               GNUNET_break (0);
1311             }
1312             else
1313             {
1314               rd_new[rd_off].data = &scratch[scratch_start];
1315               rd_new[rd_off].data_size = scratch_off - scratch_start;
1316               rd_off++;
1317             }
1318           }
1319           if (NULL != srv)
1320             GNUNET_DNSPARSER_free_srv (srv);
1321         }
1322         break;
1323       case GNUNET_NAMESTORE_TYPE_PKEY:
1324         /* tigger shortening */
1325         if (NULL != rh->shorten_key)
1326         {
1327           struct GNUNET_CRYPTO_EccPublicSignKey pub;
1328
1329           if (rd[i].data_size != sizeof (struct GNUNET_CRYPTO_EccPublicSignKey))
1330           {
1331             GNUNET_break_op (0);
1332             break;
1333           }
1334           memcpy (&pub, rd[i].data, rd[i].data_size);
1335           GNS_shorten_start (rh->ac_tail->label,
1336                              &pub,
1337                              rh->shorten_key);
1338         }
1339       default:
1340         break;
1341       }
1342     }
1343
1344     /* yes, we are done, return result */
1345     rh->proc (rh->proc_cls, rd_off, rd_new);
1346     GNS_resolver_lookup_cancel (rh);
1347     return;
1348   }
1349   /* need to recurse, check if we can */
1350   for (i=0;i<rd_count;i++)
1351   {
1352     switch (rd[i].record_type)
1353     {
1354     case GNUNET_NAMESTORE_TYPE_PKEY:
1355       /* delegation to another zone */
1356       if (sizeof (struct GNUNET_CRYPTO_EccPublicSignKey) !=
1357           rd[i].data_size)
1358       {
1359         GNUNET_break_op (0);
1360         rh->proc (rh->proc_cls, 0, NULL);
1361         GNS_resolver_lookup_cancel (rh);
1362         return;
1363       }
1364       /* expand authority chain */
1365       ac = GNUNET_new (struct AuthorityChain);
1366       ac->rh = rh;
1367       ac->gns_authority = GNUNET_YES;
1368       memcpy (&ac->authority_info.gns_authority,
1369               rd[i].data,
1370               sizeof (struct GNUNET_CRYPTO_EccPublicSignKey));
1371       ac->label = resolver_lookup_get_next_label (rh);
1372       /* tigger shortening */
1373       if (NULL != rh->shorten_key)
1374         GNS_shorten_start (rh->ac_tail->label,
1375                            &ac->authority_info.gns_authority,
1376                            rh->shorten_key);
1377       /* add AC to tail */
1378       GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1379                                         rh->ac_tail,
1380                                         ac);
1381       /* recurse */
1382       rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1383                                               rh);
1384       break;
1385     case GNUNET_DNSPARSER_TYPE_NS:
1386       /* resolution continues within DNS */
1387       if (GNUNET_DNSPARSER_MAX_NAME_LENGTH < rd[i].data_size)
1388       {
1389         GNUNET_break_op (0);
1390         rh->proc (rh->proc_cls, 0, NULL);
1391         GNS_resolver_lookup_cancel (rh);
1392         return;
1393       }
1394       /* find associated A/AAAA record */
1395       sa = NULL;
1396       sa_len = 0;
1397       for (j=0;j<rd_count;j++)
1398       {
1399         switch (rd[j].record_type)
1400         {
1401         case GNUNET_DNSPARSER_TYPE_A:
1402           if (sizeof (struct in_addr) != rd[i].data_size)
1403           {
1404             GNUNET_break_op (0);
1405             rh->proc (rh->proc_cls, 0, NULL);
1406             GNS_resolver_lookup_cancel (rh);
1407             return;
1408           }
1409           /* FIXME: might want to check if we support IPv4 here,
1410              and otherwise skip this one and hope we find another */
1411           memset (&v4, 0, sizeof (v4));
1412           sa_len = sizeof (v4);
1413           v4.sin_family = AF_INET;
1414           v4.sin_port = htons (53);
1415 #if HAVE_SOCKADDR_IN_SIN_LEN
1416           v4.sin_len = (u_char) sa_len;
1417 #endif
1418           memcpy (&v4.sin_addr,
1419                   rd[j].data,
1420                   sizeof (struct in_addr));
1421           sa = (struct sockaddr *) &v4;
1422           break;
1423         case GNUNET_DNSPARSER_TYPE_AAAA:
1424           if (sizeof (struct in6_addr) != rd[i].data_size)
1425           {
1426             GNUNET_break_op (0);
1427             rh->proc (rh->proc_cls, 0, NULL);
1428             GNS_resolver_lookup_cancel (rh);
1429             return;
1430           }
1431           /* FIXME: might want to check if we support IPv6 here,
1432              and otherwise skip this one and hope we find another */
1433           memset (&v6, 0, sizeof (v6));
1434           sa_len = sizeof (v6);
1435           v6.sin6_family = AF_INET6;
1436           v6.sin6_port = htons (53);
1437 #if HAVE_SOCKADDR_IN_SIN_LEN
1438           v6.sin6_len = (u_char) sa_len;
1439 #endif
1440           memcpy (&v6.sin6_addr,
1441                   rd[j].data,
1442                   sizeof (struct in6_addr));
1443           sa = (struct sockaddr *) &v6;
1444           break;
1445         default:
1446           break;
1447         }
1448         if (NULL != sa)
1449           break;
1450       }
1451       if (NULL == sa)
1452       {
1453         /* we cannot continue; NS without A/AAAA */
1454         rh->proc (rh->proc_cls, 0, NULL);
1455         GNS_resolver_lookup_cancel (rh);
1456         return;
1457       }
1458       /* expand authority chain */
1459       ac = GNUNET_new (struct AuthorityChain);
1460       ac->rh = rh;
1461       strncpy (ac->authority_info.dns_authority.name,
1462                rd[i].data,
1463                rd[i].data_size);
1464       ac->authority_info.dns_authority.name[rd[i].data_size] = '\0';
1465       memcpy (&ac->authority_info.dns_authority.dns_ip,
1466               sa,
1467               sa_len);
1468       /* for DNS recursion, the label is the full DNS name,
1469          created from the remainder of the GNS name and the
1470          name in the NS record */
1471       GNUNET_asprintf (&ac->label,
1472                        "%.*s%s",
1473                        (int) rh->name_resolution_pos,
1474                        rh->name,
1475                        ac->authority_info.dns_authority.name);
1476       GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1477                                         rh->ac_tail,
1478                                         ac);
1479       if (strlen (ac->label) > GNUNET_DNSPARSER_MAX_NAME_LENGTH)
1480       {
1481         GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1482                     _("GNS lookup resulted in DNS name that is too long (`%s')\n"),
1483                     ac->label);
1484         rh->proc (rh->proc_cls, 0, NULL);
1485         GNS_resolver_lookup_cancel (rh);
1486         return;
1487       }
1488       /* recurse */
1489       rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1490                                               rh);
1491       return;
1492     case GNUNET_DNSPARSER_TYPE_CNAME:
1493       cname = GNUNET_strndup (rd[i].data,
1494                               rd[i].data_size);
1495       handle_gns_cname_result (rh,
1496                                cname);
1497       GNUNET_free (cname);
1498       return;
1499       /* FIXME: handle DNAME */
1500     default:
1501       /* skip */
1502       break;
1503     }
1504   }
1505   GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1506               _("GNS lookup recursion failed (no delegation record found)\n"));
1507   rh->proc (rh->proc_cls, 0, NULL);
1508   GNS_resolver_lookup_cancel (rh);
1509 }
1510
1511
1512 /**
1513  * Function called once the namestore has completed the request for
1514  * caching a block.
1515  *
1516  * @param cls closure with the 'struct GNS_ResolverHandle'
1517  * @param success #GNUNET_OK on success
1518  * @param emsg error message
1519  */
1520 static void
1521 namestore_cache_continuation (void *cls,
1522                               int32_t success,
1523                               const char *emsg)
1524 {
1525   struct GNS_ResolverHandle *rh = cls;
1526
1527   rh->namestore_qe = NULL;
1528   if (NULL != emsg)
1529     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1530                 _("Failed to cache GNS resolution: %s\n"),
1531                 emsg);
1532 }
1533
1534
1535 /**
1536  * Iterator called on each result obtained for a DHT
1537  * operation that expects a reply
1538  *
1539  * @param cls closure with the 'struct GNS_ResolverHandle'
1540  * @param exp when will this value expire
1541  * @param key key of the result
1542  * @param get_path peers on reply path (or NULL if not recorded)
1543  *                 [0] = datastore's first neighbor, [length - 1] = local peer
1544  * @param get_path_length number of entries in get_path
1545  * @param put_path peers on the PUT path (or NULL if not recorded)
1546  *                 [0] = origin, [length - 1] = datastore
1547  * @param put_path_length number of entries in get_path
1548  * @param type type of the result
1549  * @param size number of bytes in data
1550  * @param data pointer to the result data
1551  */
1552 static void
1553 handle_dht_response (void *cls,
1554                      struct GNUNET_TIME_Absolute exp,
1555                      const struct GNUNET_HashCode * key,
1556                      const struct GNUNET_PeerIdentity *get_path,
1557                      unsigned int get_path_length,
1558                      const struct GNUNET_PeerIdentity *put_path,
1559                      unsigned int put_path_length,
1560                      enum GNUNET_BLOCK_Type type,
1561                      size_t size, const void *data)
1562 {
1563   struct GNS_ResolverHandle *rh = cls;
1564   struct AuthorityChain *ac = rh->ac_tail;
1565   const struct GNUNET_NAMESTORE_Block *block;
1566
1567   GNUNET_DHT_get_stop (rh->get_handle);
1568   rh->get_handle = NULL;
1569   GNUNET_CONTAINER_heap_remove_node (rh->dht_heap_node);
1570   rh->dht_heap_node = NULL;
1571   if (size < sizeof (struct GNUNET_NAMESTORE_Block))
1572   {
1573     /* how did this pass DHT block validation!? */
1574     GNUNET_break (0);
1575     rh->proc (rh->proc_cls, 0, NULL);
1576     GNS_resolver_lookup_cancel (rh);
1577     return;
1578   }
1579   block = data;
1580   if (size !=
1581       ntohs (block->purpose.size) +
1582       sizeof (struct GNUNET_CRYPTO_EccPublicSignKey) +
1583       sizeof (struct GNUNET_CRYPTO_EccSignature))
1584   {
1585     /* how did this pass DHT block validation!? */
1586     GNUNET_break (0);
1587     rh->proc (rh->proc_cls, 0, NULL);
1588     GNS_resolver_lookup_cancel (rh);
1589     return;
1590   }
1591   if (GNUNET_OK !=
1592       GNUNET_NAMESTORE_block_decrypt (block,
1593                                       &ac->authority_info.gns_authority,
1594                                       ac->label,
1595                                       &handle_gns_resolution_result,
1596                                       rh))
1597   {
1598     GNUNET_break_op (0); /* block was ill-formed */
1599     rh->proc (rh->proc_cls, 0, NULL);
1600     GNS_resolver_lookup_cancel (rh);
1601     return;
1602   }
1603   /* Cache well-formed blocks */
1604   rh->namestore_qe = GNUNET_NAMESTORE_block_cache (namestore_handle,
1605                                                    block,
1606                                                    &namestore_cache_continuation,
1607                                                    rh);
1608 }
1609
1610
1611 /**
1612  * Process a record that was stored in the namestore.
1613  *
1614  * @param cls closure with the `struct GNS_ResolverHandle`
1615  * @param block block that was stored in the namestore
1616  */
1617 static void
1618 handle_namestore_block_response (void *cls,
1619                                  const struct GNUNET_NAMESTORE_Block *block)
1620 {
1621   struct GNS_ResolverHandle *rh = cls;
1622   struct GNS_ResolverHandle *rx;
1623   struct AuthorityChain *ac = rh->ac_tail;
1624   const char *label = ac->label;
1625   const struct GNUNET_CRYPTO_EccPublicSignKey *auth = &ac->authority_info.gns_authority;
1626   struct GNUNET_HashCode query;
1627
1628   GNUNET_NAMESTORE_query_from_public_key (auth,
1629                                           label,
1630                                           &query);
1631   rh->namestore_qe = NULL;
1632   if ( (GNUNET_NO == rh->only_cached) &&
1633        ( (NULL == block) ||
1634          (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us) ) )
1635   {
1636     /* Namestore knows nothing; try DHT lookup */
1637     rh->get_handle = GNUNET_DHT_get_start (dht_handle,
1638                                            GNUNET_BLOCK_TYPE_GNS_NAMERECORD,
1639                                            &query,
1640                                            DHT_GNS_REPLICATION_LEVEL,
1641                                            GNUNET_DHT_RO_DEMULTIPLEX_EVERYWHERE,
1642                                            NULL, 0,
1643                                            &handle_dht_response, rh);
1644     rh->dht_heap_node = GNUNET_CONTAINER_heap_insert (dht_lookup_heap,
1645                                                       rh,
1646                                                       GNUNET_TIME_absolute_get ().abs_value_us);
1647     if (GNUNET_CONTAINER_heap_get_size (dht_lookup_heap) > max_allowed_background_queries)
1648     {
1649       /* fail longest-standing DHT request */
1650       rx = GNUNET_CONTAINER_heap_peek (dht_lookup_heap);
1651       GNUNET_assert (NULL != rx);
1652       rx->proc (rx->proc_cls, 0, NULL);
1653       GNS_resolver_lookup_cancel (rx);
1654     }
1655     return;
1656   }
1657   if ( (NULL == block) ||
1658        (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us) )
1659   {
1660     /* DHT not permitted and no local result, fail */
1661     rh->proc (rh->proc_cls, 0, NULL);
1662     GNS_resolver_lookup_cancel (rh);
1663     return;
1664   }
1665   if (GNUNET_OK !=
1666       GNUNET_NAMESTORE_block_decrypt (block,
1667                                       auth,
1668                                       label,
1669                                       &handle_gns_resolution_result,
1670                                       rh))
1671   {
1672     GNUNET_break_op (0); /* block was ill-formed */
1673     rh->proc (rh->proc_cls, 0, NULL);
1674     GNS_resolver_lookup_cancel (rh);
1675     return;
1676   }
1677 }
1678
1679
1680 /**
1681  * Lookup tail of our authority chain in the namestore.
1682  *
1683  * @param rh query we are processing
1684  */
1685 static void
1686 recursive_gns_resolution_namestore (struct GNS_ResolverHandle *rh)
1687 {
1688   struct AuthorityChain *ac = rh->ac_tail;
1689   struct GNUNET_HashCode query;
1690
1691   GNUNET_NAMESTORE_query_from_public_key (&ac->authority_info.gns_authority,
1692                                           ac->label,
1693                                           &query);
1694   rh->namestore_qe = GNUNET_NAMESTORE_lookup_block (namestore_handle,
1695                                                     &query,
1696                                                     &handle_namestore_block_response,
1697                                                     rh);
1698 }
1699
1700
1701 /**
1702  * Task scheduled to continue with the resolution process.
1703  *
1704  * @param cls the `struct GNS_ResolverHandle` of the resolution
1705  * @param tc task context
1706  */
1707 static void
1708 recursive_resolution (void *cls,
1709                       const struct GNUNET_SCHEDULER_TaskContext *tc)
1710 {
1711   struct GNS_ResolverHandle *rh = cls;
1712
1713   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
1714   if (MAX_RECURSION < rh->loop_limiter++)
1715   {
1716     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1717                 "Encountered unbounded recursion resolving `%s'\n",
1718                 rh->name);
1719     rh->proc (rh->proc_cls, 0, NULL);
1720     GNS_resolver_lookup_cancel (rh);
1721     return;
1722   }
1723   if (GNUNET_YES == rh->ac_tail->gns_authority)
1724     recursive_gns_resolution_namestore (rh);
1725   else
1726     recursive_dns_resolution (rh);
1727 }
1728
1729
1730 /**
1731  * Begin the resolution process from 'name', starting with
1732  * the identification of the zone specified by 'name'.
1733  *
1734  * @param rh resolution to perform
1735  */
1736 static void
1737 start_resolver_lookup (struct GNS_ResolverHandle *rh)
1738 {
1739   struct AuthorityChain *ac;
1740   char *x;
1741   char *y;
1742   char *pkey;
1743
1744   if ( ( (GNUNET_YES == is_canonical (rh->name)) &&
1745          (0 != strcmp (GNUNET_GNS_TLD, rh->name)) ) ||
1746        ( (GNUNET_YES != is_gnu_tld (rh->name)) &&
1747          (GNUNET_YES != is_zkey_tld (rh->name)) ) )
1748   {
1749     /* use standard DNS lookup */
1750     int af;
1751
1752     switch (rh->record_type)
1753     {
1754     case GNUNET_DNSPARSER_TYPE_A:
1755       af = AF_INET;
1756       break;
1757     case GNUNET_DNSPARSER_TYPE_AAAA:
1758       af = AF_INET6;
1759       break;
1760     default:
1761       af = AF_UNSPEC;
1762       break;
1763     }
1764     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1765                 "Doing standard DNS lookup for `%s'\n",
1766                 rh->name);
1767     rh->std_resolve = GNUNET_RESOLVER_ip_get (rh->name,
1768                                               af,
1769                                               DNS_LOOKUP_TIMEOUT,
1770                                               &handle_dns_result,
1771                                               rh);
1772     return;
1773   }
1774   if (is_zkey_tld (rh->name))
1775   {
1776     /* Name ends with ".zkey", try to replace authority zone with zkey
1777        authority */
1778     GNUNET_free (resolver_lookup_get_next_label (rh)); /* will return "zkey" */
1779     x = resolver_lookup_get_next_label (rh); /* will return 'x' coordinate */
1780     y = resolver_lookup_get_next_label (rh); /* will return 'y' coordinate */
1781     GNUNET_asprintf (&pkey,
1782                      "%s%s",
1783                      x, y);
1784     if ( (NULL == x) ||
1785          (NULL == y) ||
1786          (GNUNET_OK !=
1787           GNUNET_CRYPTO_ecc_public_sign_key_from_string (pkey,
1788                                                     strlen (pkey),
1789                                                     &rh->authority_zone)) )
1790     {
1791       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1792                   _("Hostname `%s' is not well-formed, resolution fails\n"),
1793                   rh->name);
1794       rh->task_id = GNUNET_SCHEDULER_add_now (&fail_resolution, rh);
1795     }
1796     GNUNET_free_non_null (x);
1797     GNUNET_free_non_null (y);
1798     GNUNET_free (pkey);
1799   }
1800   else
1801   {
1802     /* Name ends with ".gnu", eat ".gnu" and continue with resolution */
1803     GNUNET_free (resolver_lookup_get_next_label (rh));
1804   }
1805   ac = GNUNET_new (struct AuthorityChain);
1806   ac->rh = rh;
1807   ac->label = resolver_lookup_get_next_label (rh);
1808   if (NULL == ac->label)
1809     /* name was just "gnu", so we default to label '+' */
1810     ac->label = GNUNET_strdup (GNUNET_GNS_MASTERZONE_STR);
1811   ac->gns_authority = GNUNET_YES;
1812   ac->authority_info.gns_authority = rh->authority_zone;
1813   GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1814                                     rh->ac_tail,
1815                                     ac);
1816   rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1817                                           rh);
1818 }
1819
1820
1821 /**
1822  * Lookup of a record in a specific zone calls lookup result processor
1823  * on result.
1824  *
1825  * @param zone the zone to perform the lookup in
1826  * @param record_type the record type to look up
1827  * @param name the name to look up
1828  * @param shorten_key a private key for use with PSEU import (can be NULL)
1829  * @param only_cached #GNUNET_NO to only check locally not DHT for performance
1830  * @param proc the processor to call on result
1831  * @param proc_cls the closure to pass to @a proc
1832  * @return handle to cancel operation
1833  */
1834 struct GNS_ResolverHandle *
1835 GNS_resolver_lookup (const struct GNUNET_CRYPTO_EccPublicSignKey *zone,
1836                      uint32_t record_type,
1837                      const char *name,
1838                      const struct GNUNET_CRYPTO_EccPrivateKey *shorten_key,
1839                      int only_cached,
1840                      GNS_ResultProcessor proc, void *proc_cls)
1841 {
1842   struct GNS_ResolverHandle *rh;
1843
1844   rh = GNUNET_new (struct GNS_ResolverHandle);
1845   GNUNET_CONTAINER_DLL_insert (rlh_head,
1846                                rlh_tail,
1847                                rh);
1848   rh->authority_zone = *zone;
1849   rh->proc = proc;
1850   rh->proc_cls = proc_cls;
1851   rh->only_cached = only_cached;
1852   rh->record_type = record_type;
1853   rh->name = GNUNET_strdup (name);
1854   rh->name_resolution_pos = strlen (name);
1855   if (NULL != shorten_key)
1856   {
1857     rh->shorten_key = GNUNET_new (struct GNUNET_CRYPTO_EccPrivateKey);
1858     *rh->shorten_key = *shorten_key;
1859   }
1860   start_resolver_lookup (rh);
1861   return rh;
1862 }
1863
1864
1865 /**
1866  * Cancel active resolution (i.e. client disconnected).
1867  *
1868  * @param rh resolution to abort
1869  */
1870 void
1871 GNS_resolver_lookup_cancel (struct GNS_ResolverHandle *rh)
1872 {
1873   struct DnsResult *dr;
1874   struct AuthorityChain *ac;
1875   struct VpnContext *vpn_ctx;
1876
1877   GNUNET_CONTAINER_DLL_remove (rlh_head,
1878                                rlh_tail,
1879                                rh);
1880   while (NULL != (ac = rh->ac_head))
1881   {
1882     GNUNET_CONTAINER_DLL_remove (rh->ac_head,
1883                                  rh->ac_tail,
1884                                  ac);
1885     GNUNET_free (ac->label);
1886     GNUNET_free (ac);
1887   }
1888   if (GNUNET_SCHEDULER_NO_TASK != rh->task_id)
1889   {
1890     GNUNET_SCHEDULER_cancel (rh->task_id);
1891     rh->task_id = GNUNET_SCHEDULER_NO_TASK;
1892   }
1893   if (NULL != rh->get_handle)
1894   {
1895     GNUNET_DHT_get_stop (rh->get_handle);
1896     rh->get_handle = NULL;
1897   }
1898   if (NULL != rh->dht_heap_node)
1899   {
1900     GNUNET_CONTAINER_heap_remove_node (rh->dht_heap_node);
1901     rh->dht_heap_node = NULL;
1902   }
1903   if (NULL != (vpn_ctx = rh->vpn_ctx))
1904   {
1905     GNUNET_VPN_cancel_request (vpn_ctx->vpn_request);
1906     GNUNET_free (vpn_ctx->rd_data);
1907     GNUNET_free (vpn_ctx);
1908   }
1909   if (NULL != rh->dns_request)
1910   {
1911     GNUNET_DNSSTUB_resolve_cancel (rh->dns_request);
1912     rh->dns_request = NULL;
1913   }
1914   if (NULL != rh->namestore_qe)
1915   {
1916     GNUNET_NAMESTORE_cancel (rh->namestore_qe);
1917     rh->namestore_qe = NULL;
1918   }
1919   if (NULL != rh->std_resolve)
1920   {
1921     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1922                 "Canceling standard DNS resolution\n");
1923     GNUNET_RESOLVER_request_cancel (rh->std_resolve);
1924     rh->std_resolve = NULL;
1925   }
1926   while (NULL != (dr = rh->dns_result_head))
1927   {
1928     GNUNET_CONTAINER_DLL_remove (rh->dns_result_head,
1929                                  rh->dns_result_tail,
1930                                  dr);
1931     GNUNET_free (dr);
1932   }
1933   GNUNET_free_non_null (rh->shorten_key);
1934   GNUNET_free (rh->name);
1935   GNUNET_free (rh);
1936 }
1937
1938
1939 /* ***************** Resolver initialization ********************* */
1940
1941
1942 /**
1943  * Initialize the resolver
1944  *
1945  * @param nh the namestore handle
1946  * @param dht the dht handle
1947  * @param c configuration handle
1948  * @param max_bg_queries maximum number of parallel background queries in dht
1949  */
1950 void
1951 GNS_resolver_init (struct GNUNET_NAMESTORE_Handle *nh,
1952                    struct GNUNET_DHT_Handle *dht,
1953                    const struct GNUNET_CONFIGURATION_Handle *c,
1954                    unsigned long long max_bg_queries)
1955 {
1956   char *dns_ip;
1957
1958   cfg = c;
1959   namestore_handle = nh;
1960   dht_handle = dht;
1961   dht_lookup_heap =
1962     GNUNET_CONTAINER_heap_create (GNUNET_CONTAINER_HEAP_ORDER_MIN);
1963   max_allowed_background_queries = max_bg_queries;
1964   if (GNUNET_OK !=
1965       GNUNET_CONFIGURATION_get_value_string (c,
1966                                              "gns",
1967                                              "DNS_RESOLVER",
1968                                              &dns_ip))
1969   {
1970     /* user did not specify DNS resolver, use 8.8.8.8 */
1971     dns_ip = GNUNET_strdup ("8.8.8.8");
1972   }
1973   dns_handle = GNUNET_DNSSTUB_start (dns_ip);
1974   GNUNET_free (dns_ip);
1975   vpn_handle = GNUNET_VPN_connect (cfg);
1976 }
1977
1978
1979 /**
1980  * Shutdown resolver
1981  */
1982 void
1983 GNS_resolver_done ()
1984 {
1985   struct GNS_ResolverHandle *rh;
1986
1987   /* abort active resolutions */
1988   while (NULL != (rh = rlh_head))
1989   {
1990     rh->proc (rh->proc_cls, 0, NULL);
1991     GNS_resolver_lookup_cancel (rh);
1992   }
1993   GNUNET_CONTAINER_heap_destroy (dht_lookup_heap);
1994   dht_lookup_heap = NULL;
1995   GNUNET_DNSSTUB_stop (dns_handle);
1996   dns_handle = NULL;
1997   GNUNET_VPN_disconnect (vpn_handle);
1998   vpn_handle = NULL;
1999   dht_handle = NULL;
2000   namestore_handle = NULL;
2001 }
2002
2003
2004 /* *************** common helper functions (do not really belong here) *********** */
2005
2006 /**
2007  * Checks if @a name ends in ".TLD"
2008  *
2009  * @param name the name to check
2010  * @param tld the TLD to check for
2011  * @return GNUNET_YES or GNUNET_NO
2012  */
2013 int
2014 is_tld (const char* name, const char* tld)
2015 {
2016   size_t offset = 0;
2017
2018   if (strlen (name) <= strlen (tld))
2019     return GNUNET_NO;
2020   offset = strlen (name) - strlen (tld);
2021   if (0 != strcmp (name + offset, tld))
2022     return GNUNET_NO;
2023   return GNUNET_YES;
2024 }
2025
2026
2027 /* end of gnunet-service-gns_resolver.c */