src/gns/gnunet-service-gns_resolver.c

   1 /*
   2      This file is part of GNUnet.
   3      (C) 2011-2013 Christian Grothoff (and other contributing authors)
   4
   5      GNUnet is free software; you can redistribute it and/or modify
   6      it under the terms of the GNU General Public License as published
   7      by the Free Software Foundation; either version 3, or (at your
   8      option) any later version.
   9
  10      GNUnet is distributed in the hope that it will be useful, but
  11      WITHOUT ANY WARRANTY; without even the implied warranty of
  12      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13      General Public License for more details.
  14
  15      You should have received a copy of the GNU General Public License
  16      along with GNUnet; see the file COPYING.  If not, write to the
  17      Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18      Boston, MA 02111-1307, USA.
  19 */
  20
  21 /**
  22  * @file gns/gnunet-service-gns_resolver.c
  23  * @brief GNU Name System resolver logic
  24  * @author Martin Schanzenbach
  25  * @author Christian Grothoff
  26  *
  27  * TODO:
  28  * - GNS: handle special SRV names --- no delegation, direct lookup;
  29  *        can likely be done in 'resolver_lookup_get_next_label'. (#3003)
  30  * - revocation checks (use REVOCATION service!), (#3004)
  31  * - DNAME support (#3005)
  32  */
  33 #include "platform.h"
  34 #include "gnunet_util_lib.h"
  35 #include "gnunet_dnsstub_lib.h"
  36 #include "gnunet_dht_service.h"
  37 #include "gnunet_gnsrecord_lib.h"
  38 #include "gnunet_namecache_service.h"
  39 #include "gnunet_namestore_service.h"
  40 #include "gnunet_dns_service.h"
  41 #include "gnunet_resolver_service.h"
  42 #include "gnunet_revocation_service.h"
  43 #include "gnunet_dnsparser_lib.h"
  44 #include "gnunet_tun_lib.h"
  45 #include "gnunet_gns_service.h"
  46 #include "gns.h"
  47 #include "gnunet-service-gns_resolver.h"
  48 #include "gnunet-service-gns_shorten.h"
  49 #include "gnunet_vpn_service.h"
  50
  51
  52 /**
  53  * Default DHT timeout for lookups.
  54  */
  55 #define DHT_LOOKUP_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 60)
  56
  57 /**
  58  * Default timeout for DNS lookups.
  59  */
  60 #define DNS_LOOKUP_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)
  61
  62 /**
  63  * Default timeout for VPN redirections.
  64  */
  65 #define VPN_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 30)
  66
  67 /**
  68  * DHT replication level
  69  */
  70 #define DHT_GNS_REPLICATION_LEVEL 5
  71
  72 /**
  73  * How deep do we allow recursions to go before we abort?
  74  */
  75 #define MAX_RECURSION 256
  76
  77
  78 /**
  79  * DLL to hold the authority chain we had to pass in the resolution
  80  * process.
  81  */
  82 struct AuthorityChain
  83 {
  84   /**
  85    * This is a DLL.
  86    */
  87   struct AuthorityChain *prev;
  88
  89   /**
  90    * This is a DLL.
  91    */
  92   struct AuthorityChain *next;
  93
  94   /**
  95    * Resolver handle this entry in the chain belongs to.
  96    */
  97   struct GNS_ResolverHandle *rh;
  98
  99   /**
 100    * label/name corresponding to the authority
 101    */
 102   char *label;
 103
 104   /**
 105    * label/name suggested for shortening to the authority
 106    */
 107   char *suggested_shortening_label;
 108
 109   /**
 110    * Do we already try to shorten this authority?
 111    */
 112   int shortening_started;
 113
 114   /**
 115    * #GNUNET_YES if the authority was a GNS authority,
 116    * #GNUNET_NO if the authority was a DNS authority.
 117    */
 118   int gns_authority;
 119
 120   /**
 121    * Information about the resolver authority for this label.
 122    */
 123   union
 124   {
 125
 126     /**
 127      * The zone of the GNS authority
 128      */
 129     struct GNUNET_CRYPTO_EcdsaPublicKey gns_authority;
 130
 131     struct
 132     {
 133       /**
 134        * Domain of the DNS resolver that is the authority.
 135        * (appended to construct the DNS name to resolve;
 136        * this is NOT the DNS name of the DNS server!).
 137        */
 138       char name[GNUNET_DNSPARSER_MAX_NAME_LENGTH + 1];
 139
 140       /**
 141        * IP address of the DNS resolver that is authoritative.
 142        * (this implementation currently only supports one
 143        * IP at a time).
 144        */
 145       struct sockaddr_storage dns_ip;
 146
 147     } dns_authority;
 148
 149   } authority_info;
 150
 151 };
 152
 153
 154 /**
 155  * A result we got from DNS.
 156  */
 157 struct DnsResult
 158 {
 159
 160   /**
 161    * Kept in DLL.
 162    */
 163   struct DnsResult *next;
 164
 165   /**
 166    * Kept in DLL.
 167    */
 168   struct DnsResult *prev;
 169
 170   /**
 171    * Binary value stored in the DNS record (appended to this struct)
 172    */
 173   const void *data;
 174
 175   /**
 176    * Expiration time for the DNS record, 0 if we didn't
 177    * get anything useful (i.e. 'gethostbyname' was used).
 178    */
 179   uint64_t expiration_time;
 180
 181   /**
 182    * Number of bytes in @e data.
 183    */
 184   size_t data_size;
 185
 186   /**
 187    * Type of the GNS/DNS record.
 188    */
 189   uint32_t record_type;
 190
 191 };
 192
 193
 194 /**
 195  * Closure for #vpn_allocation_cb.
 196  */
 197 struct VpnContext
 198 {
 199
 200   /**
 201    * Which resolution process are we processing.
 202    */
 203   struct GNS_ResolverHandle *rh;
 204
 205   /**
 206    * Handle to the VPN request that we were performing.
 207    */
 208   struct GNUNET_VPN_RedirectionRequest *vpn_request;
 209
 210   /**
 211    * Number of records serialized in @e rd_data.
 212    */
 213   unsigned int rd_count;
 214
 215   /**
 216    * Serialized records.
 217    */
 218   char *rd_data;
 219
 220   /**
 221    * Number of bytes in @e rd_data.
 222    */
 223   size_t rd_data_size;
 224 };
 225
 226
 227 /**
 228  * Information we keep during the resolution of an
 229  * IP address for a DNS server while handling a
 230  * GNS2DNS record.
 231  */
 232 struct Gns2DnsContext
 233 {
 234
 235   /**
 236    * DNS domain in which the resolution will continue
 237    * (first part of the GNS2DNS record).
 238    */
 239   char *ns;
 240
 241   /**
 242    * Handle for the resolution of the IP part of the
 243    * GNS2DNS record.  Will return to us the addresses
 244    * of the DNS resolver to use.
 245    */
 246   struct GNS_ResolverHandle *rh;
 247
 248 };
 249
 250
 251 /**
 252  * Handle to a currenty pending resolution.  On result (positive or
 253  * negative) the #GNS_ResultProcessor is called.
 254  */
 255 struct GNS_ResolverHandle
 256 {
 257
 258   /**
 259    * DLL
 260    */
 261   struct GNS_ResolverHandle *next;
 262
 263   /**
 264    * DLL
 265    */
 266   struct GNS_ResolverHandle *prev;
 267
 268   /**
 269    * The top-level GNS authoritative zone to query
 270    */
 271   struct GNUNET_CRYPTO_EcdsaPublicKey authority_zone;
 272
 273   /**
 274    * called when resolution phase finishes
 275    */
 276   GNS_ResultProcessor proc;
 277
 278   /**
 279    * closure passed to @e proc
 280    */
 281   void* proc_cls;
 282
 283   /**
 284    * Handle used during GNS2DNS resolution for looking up the
 285    * IP address of the DNS server.
 286    */
 287   struct Gns2DnsContext *g2dc;
 288
 289   /**
 290    * Handle for DHT lookups. should be NULL if no lookups are in progress
 291    */
 292   struct GNUNET_DHT_GetHandle *get_handle;
 293
 294   /**
 295    * Handle to a VPN request, NULL if none is active.
 296    */
 297   struct VpnContext *vpn_ctx;
 298
 299   /**
 300    * Socket for a DNS request, NULL if none is active.
 301    */
 302   struct GNUNET_DNSSTUB_RequestSocket *dns_request;
 303
 304   /**
 305    * Handle for standard DNS resolution, NULL if none is active.
 306    */
 307   struct GNUNET_RESOLVER_RequestHandle *std_resolve;
 308
 309   /**
 310    * Pending Namecache lookup task
 311    */
 312   struct GNUNET_NAMECACHE_QueueEntry *namecache_qe;
 313
 314   /**
 315    * Pending revocation check.
 316    */
 317   struct GNUNET_REVOCATION_Query *rev_check;
 318
 319   /**
 320    * Heap node associated with this lookup.  Used to limit number of
 321    * concurrent requests.
 322    */
 323   struct GNUNET_CONTAINER_HeapNode *dht_heap_node;
 324
 325   /**
 326    * DLL to store the authority chain
 327    */
 328   struct AuthorityChain *ac_head;
 329
 330   /**
 331    * DLL to store the authority chain
 332    */
 333   struct AuthorityChain *ac_tail;
 334
 335   /**
 336    * Private key of the shorten zone, NULL to not shorten.
 337    */
 338   struct GNUNET_CRYPTO_EcdsaPrivateKey *shorten_key;
 339
 340   /**
 341    * ID of a task associated with the resolution process.
 342    */
 343   GNUNET_SCHEDULER_TaskIdentifier task_id;
 344
 345   /**
 346    * The name to resolve
 347    */
 348   char *name;
 349
 350   /**
 351    * DLL of results we got from DNS.
 352    */
 353   struct DnsResult *dns_result_head;
 354
 355   /**
 356    * DLL of results we got from DNS.
 357    */
 358   struct DnsResult *dns_result_tail;
 359
 360   /**
 361    * Current offset in 'name' where we are resolving.
 362    */
 363   size_t name_resolution_pos;
 364
 365   /**
 366    * Use only cache
 367    */
 368   int only_cached;
 369
 370   /**
 371    * Desired type for the resolution.
 372    */
 373   int record_type;
 374
 375   /**
 376    * We increment the loop limiter for each step in a recursive
 377    * resolution.  If it passes our threshold (i.e. due to
 378    * self-recursion in the resolution, i.e CNAME fun), we stop.
 379    */
 380   unsigned int loop_limiter;
 381
 382 };
 383
 384
 385 /**
 386  * Active namestore caching operations.
 387  */
 388 struct CacheOps
 389 {
 390
 391   /**
 392    * Organized in a DLL.
 393    */
 394   struct CacheOps *next;
 395
 396   /**
 397    * Organized in a DLL.
 398    */
 399   struct CacheOps *prev;
 400
 401   /**
 402    * Pending Namestore caching task.
 403    */
 404   struct GNUNET_NAMECACHE_QueueEntry *namecache_qe_cache;
 405
 406 };
 407
 408
 409 /**
 410  * Our handle to the namecache service
 411  */
 412 static struct GNUNET_NAMECACHE_Handle *namecache_handle;
 413
 414 /**
 415  * Our handle to the vpn service
 416  */
 417 static struct GNUNET_VPN_Handle *vpn_handle;
 418
 419 /**
 420  * Resolver handle to the dht
 421  */
 422 static struct GNUNET_DHT_Handle *dht_handle;
 423
 424 /**
 425  * Handle to perform DNS lookups.
 426  */
 427 static struct GNUNET_DNSSTUB_Context *dns_handle;
 428
 429 /**
 430  * Heap for limiting parallel DHT lookups
 431  */
 432 static struct GNUNET_CONTAINER_Heap *dht_lookup_heap;
 433
 434 /**
 435  * Maximum amount of parallel queries to the DHT
 436  */
 437 static unsigned long long max_allowed_background_queries;
 438
 439 /**
 440  * Head of resolver lookup list
 441  */
 442 static struct GNS_ResolverHandle *rlh_head;
 443
 444 /**
 445  * Tail of resolver lookup list
 446  */
 447 static struct GNS_ResolverHandle *rlh_tail;
 448
 449 /**
 450  * Organized in a DLL.
 451  */
 452 static struct CacheOps *co_head;
 453
 454 /**
 455  * Organized in a DLL.
 456  */
 457 static struct CacheOps *co_tail;
 458
 459 /**
 460  * Use namecache
 461  */
 462 static int use_cache;
 463
 464 /**
 465  * Global configuration.
 466  */
 467 static const struct GNUNET_CONFIGURATION_Handle *cfg;
 468
 469 #if 0
 470 /**
 471  * Check if name is in srv format (_x._y.xxx)
 472  *
 473  * @param name
 474  * @return #GNUNET_YES if true
 475  */
 476 static int
 477 is_srv (const char *name)
 478 {
 479   char *ndup;
 480   int ret;
 481
 482   if (*name != '_')
 483     return GNUNET_NO;
 484   if (NULL == strstr (name, "._"))
 485     return GNUNET_NO;
 486   ret = GNUNET_YES;
 487   ndup = GNUNET_strdup (name);
 488   strtok (ndup, ".");
 489   if (NULL == strtok (NULL, "."))
 490     ret = GNUNET_NO;
 491   if (NULL == strtok (NULL, "."))
 492     ret = GNUNET_NO;
 493   if (NULL != strtok (NULL, "."))
 494     ret = GNUNET_NO;
 495   GNUNET_free (ndup);
 496   return ret;
 497 }
 498 #endif
 499
 500
 501 /**
 502  * Determine if this name is canonical (is a legal name in a zone, without delegation);
 503  * note that we do not test that the name does not contain illegal characters, we only
 504  * test for delegation.  Note that service records (i.e. _foo._srv) are canonical names
 505  * even though they consist of multiple labels.
 506  *
 507  * Examples:
 508  * a.b.gnu  = not canonical
 509  * a         = canonical
 510  * _foo._srv = canonical
 511  * _f.bar    = not canonical
 512  *
 513  * @param name the name to test
 514  * @return #GNUNET_YES if canonical
 515  */
 516 static int
 517 is_canonical (const char *name)
 518 {
 519   const char *pos;
 520   const char *dot;
 521
 522   if (NULL == strchr (name, '.'))
 523     return GNUNET_YES;
 524   if ('_' != name[0])
 525     return GNUNET_NO;
 526   pos = &name[1];
 527   while (NULL != (dot = strchr (pos, '.')))
 528     if ('_' != dot[1])
 529       return GNUNET_NO;
 530     else
 531       pos = dot + 1;
 532   return GNUNET_YES;
 533 }
 534
 535 /* ************************** Resolution **************************** */
 536
 537 /**
 538  * Expands a name ending in .+ with the zone of origin.
 539  *
 540  * @param rh resolution context
 541  * @param name name to modify (to be free'd or returned)
 542  * @return updated name
 543  */
 544 static char *
 545 translate_dot_plus (struct GNS_ResolverHandle *rh,
 546                     char *name)
 547 {
 548   char *ret;
 549   size_t s_len = strlen (name);
 550
 551   if (0 != strcmp (&name[s_len - 2],
 552                    ".+"))
 553     return name; /* did not end in ".+" */
 554   GNUNET_assert (GNUNET_YES == rh->ac_tail->gns_authority);
 555   GNUNET_asprintf (&ret,
 556                    "%.*s.%s",
 557                    (int) (s_len - 2),
 558                    name,
 559                    GNUNET_GNSRECORD_pkey_to_zkey (&rh->ac_tail->authority_info.gns_authority));
 560   GNUNET_free (name);
 561   return ret;
 562 }
 563
 564
 565 /**
 566  * Task scheduled to asynchronously fail a resolution.
 567  *
 568  * @param cls the 'struct GNS_ResolverHandle' of the resolution to fail
 569  * @param tc task context
 570  */
 571 static void
 572 fail_resolution (void *cls,
 573                  const struct GNUNET_SCHEDULER_TaskContext *tc)
 574 {
 575   struct GNS_ResolverHandle *rh = cls;
 576
 577   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
 578   rh->proc (rh->proc_cls, 0, NULL);
 579   GNS_resolver_lookup_cancel (rh);
 580 }
 581
 582
 583 #if (defined WINDOWS) || (defined DARWIN)
 584 /* Don't have this on W32, here's a naive implementation
 585  * Was somehow removed on OS X ...  */
 586 void *
 587 memrchr (const void *s,
 588          int c,
 589          size_t n)
 590 {
 591   const unsigned char *ucs = s;
 592   ssize_t i;
 593
 594   for (i = n - 1; i >= 0; i--)
 595     if (c == (int) ucs[i])
 596       return (void *) &ucs[i];
 597   return NULL;
 598 }
 599 #endif
 600
 601
 602 /**
 603  * Get the next, rightmost label from the name that we are trying to resolve,
 604  * and update the resolution position accordingly.
 605  *
 606  * @param rh handle to the resolution operation to get the next label from
 607  * @return NULL if there are no more labels
 608  */
 609 static char *
 610 resolver_lookup_get_next_label (struct GNS_ResolverHandle *rh)
 611 {
 612   const char *rp;
 613   const char *dot;
 614   size_t len;
 615
 616   if (0 == rh->name_resolution_pos)
 617     return NULL;
 618   dot = memrchr (rh->name, (int) '.', rh->name_resolution_pos);
 619   if (NULL == dot)
 620   {
 621     /* done, this was the last one */
 622     len = rh->name_resolution_pos;
 623     rp = rh->name;
 624     rh->name_resolution_pos = 0;
 625   }
 626   else
 627   {
 628     /* advance by one label */
 629     len = rh->name_resolution_pos - (dot - rh->name) - 1;
 630     rp = dot + 1;
 631     rh->name_resolution_pos = dot - rh->name;
 632   }
 633   return GNUNET_strndup (rp, len);
 634 }
 635
 636
 637 /**
 638  * Gives the cummulative result obtained to the callback and clean up the request.
 639  *
 640  * @param rh resolution process that has culminated in a result
 641  */
 642 static void
 643 transmit_lookup_dns_result (struct GNS_ResolverHandle *rh)
 644 {
 645   struct DnsResult *pos;
 646   unsigned int n;
 647   unsigned int i;
 648
 649   n = 0;
 650   for (pos = rh->dns_result_head; NULL != pos; pos = pos->next)
 651     n++;
 652   {
 653     struct GNUNET_GNSRECORD_Data rd[n];
 654
 655     i = 0;
 656     for (pos = rh->dns_result_head; NULL != pos; pos = pos->next)
 657     {
 658       rd[i].data = pos->data;
 659       rd[i].data_size = pos->data_size;
 660       rd[i].record_type = pos->record_type;
 661       if (0 == pos->expiration_time)
 662       {
 663         rd[i].flags = GNUNET_GNSRECORD_RF_RELATIVE_EXPIRATION;
 664         rd[i].expiration_time = 0;
 665       }
 666       else
 667       {
 668         rd[i].flags = GNUNET_GNSRECORD_RF_NONE;
 669         rd[i].expiration_time = pos->expiration_time;
 670       }
 671       i++;
 672     }
 673     GNUNET_assert (i == n);
 674     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 675                 "Transmitting standard DNS result with %u records\n",
 676                 n);
 677     rh->proc (rh->proc_cls,
 678               n,
 679               rd);
 680   }
 681   GNS_resolver_lookup_cancel (rh);
 682 }
 683
 684
 685 /**
 686  * Add a result from DNS to the records to be returned to the application.
 687  *
 688  * @param rh resolution request to extend with a result
 689  * @param expiration_time expiration time for the answer
 690  * @param record_type DNS record type of the answer
 691  * @param data_size number of bytes in @a data
 692  * @param data binary data to return in DNS record
 693  */
 694 static void
 695 add_dns_result (struct GNS_ResolverHandle *rh,
 696                 uint64_t expiration_time,
 697                 uint32_t record_type,
 698                 size_t data_size,
 699                 const void *data)
 700 {
 701   struct DnsResult *res;
 702
 703   res = GNUNET_malloc (sizeof (struct DnsResult) + data_size);
 704   res->expiration_time = expiration_time;
 705   res->data_size = data_size;
 706   res->record_type = record_type;
 707   res->data = &res[1];
 708   memcpy (&res[1], data, data_size);
 709   GNUNET_CONTAINER_DLL_insert (rh->dns_result_head,
 710                                rh->dns_result_tail,
 711                                res);
 712 }
 713
 714
 715 /**
 716  * We had to do a DNS lookup.  Convert the result (if any) and return
 717  * it.
 718  *
 719  * @param cls closure with the `struct GNS_ResolverHandle`
 720  * @param addr one of the addresses of the host, NULL for the last address
 721  * @param addrlen length of the address
 722  */
 723 static void
 724 handle_dns_result (void *cls,
 725                    const struct sockaddr *addr,
 726                    socklen_t addrlen)
 727 {
 728   struct GNS_ResolverHandle *rh = cls;
 729   const struct sockaddr_in *sa4;
 730   const struct sockaddr_in6 *sa6;
 731
 732   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 733               "Received %u bytes of DNS IP data\n",
 734               addrlen);
 735   if (NULL == addr)
 736   {
 737     rh->std_resolve = NULL;
 738     transmit_lookup_dns_result (rh);
 739     return;
 740   }
 741   switch (addr->sa_family)
 742   {
 743   case AF_INET:
 744     sa4 = (const struct sockaddr_in *) addr;
 745     add_dns_result (rh,
 746                     0 /* expiration time is unknown */,
 747                     GNUNET_DNSPARSER_TYPE_A,
 748                     sizeof (struct in_addr),
 749                     &sa4->sin_addr);
 750     break;
 751   case AF_INET6:
 752     sa6 = (const struct sockaddr_in6 *) addr;
 753     add_dns_result (rh,
 754                     0 /* expiration time is unknown */,
 755                     GNUNET_DNSPARSER_TYPE_AAAA,
 756                     sizeof (struct in6_addr),
 757                     &sa6->sin6_addr);
 758     break;
 759   default:
 760     GNUNET_break (0);
 761     break;
 762   }
 763 }
 764
 765
 766 /**
 767  * Task scheduled to continue with the resolution process.
 768  *
 769  * @param cls the 'struct GNS_ResolverHandle' of the resolution
 770  * @param tc task context
 771  */
 772 static void
 773 recursive_resolution (void *cls,
 774                       const struct GNUNET_SCHEDULER_TaskContext *tc);
 775
 776
 777 /**
 778  * Begin the resolution process from 'name', starting with
 779  * the identification of the zone specified by 'name'.
 780  *
 781  * @param rh resolution to perform
 782  */
 783 static void
 784 start_resolver_lookup (struct GNS_ResolverHandle *rh);
 785
 786
 787 /**
 788  * Function called with the result of a DNS resolution.
 789  *
 790  * @param cls the request handle of the resolution that
 791  *        we were attempting to make
 792  * @param rs socket that received the response
 793  * @param dns dns response, never NULL
 794  * @param dns_len number of bytes in @a dns
 795  */
 796 static void
 797 dns_result_parser (void *cls,
 798                    struct GNUNET_DNSSTUB_RequestSocket *rs,
 799                    const struct GNUNET_TUN_DnsHeader *dns,
 800                    size_t dns_len)
 801 {
 802   struct GNS_ResolverHandle *rh = cls;
 803   struct GNUNET_DNSPARSER_Packet *p;
 804   const struct GNUNET_DNSPARSER_Record *rec;
 805   unsigned int rd_count;
 806   unsigned int i;
 807
 808   rh->dns_request = NULL;
 809   GNUNET_SCHEDULER_cancel (rh->task_id);
 810   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
 811   p = GNUNET_DNSPARSER_parse ((const char *) dns,
 812                               dns_len);
 813   if (NULL == p)
 814   {
 815     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
 816                 _("Failed to parse DNS response\n"));
 817     rh->proc (rh->proc_cls, 0, NULL);
 818     GNS_resolver_lookup_cancel (rh);
 819     return;
 820   }
 821   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 822               "Received DNS response for `%s' with %u answers\n",
 823               rh->ac_tail->label,
 824               (unsigned int) p->num_answers);
 825   if ( (p->num_answers > 0) &&
 826        (GNUNET_DNSPARSER_TYPE_CNAME == p->answers[0].type) &&
 827        (GNUNET_DNSPARSER_TYPE_CNAME != rh->record_type) )
 828     {
 829       GNUNET_free (rh->name);
 830       rh->name = GNUNET_strdup (p->answers[0].data.hostname);
 831       start_resolver_lookup (rh);
 832       GNUNET_DNSPARSER_free_packet (p);
 833       return;
 834     }
 835   /* FIXME: add DNAME support */
 836
 837   /* convert from (parsed) DNS to (binary) GNS format! */
 838   rd_count = p->num_answers + p->num_authority_records + p->num_additional_records;
 839   {
 840     struct GNUNET_GNSRECORD_Data rd[rd_count];
 841     unsigned int skip;
 842     char buf[UINT16_MAX];
 843     size_t buf_off;
 844     size_t buf_start;
 845
 846     buf_off = 0;
 847     skip = 0;
 848     memset (rd, 0, sizeof (rd));
 849     for (i=0;i<rd_count;i++)
 850     {
 851       if (i < p->num_answers)
 852         rec = &p->answers[i];
 853       else if (i < p->num_answers + p->num_authority_records)
 854         rec = &p->authority_records[i - p->num_answers];
 855       else
 856         rec = &p->authority_records[i - p->num_answers - p->num_authority_records];
 857       /* As we copied the full DNS name to 'rh->ac_tail->label', this
 858          should be the correct check to see if this record is actually
 859          a record for our label... */
 860       if (0 != strcmp (rec->name,
 861                        rh->ac_tail->label))
 862       {
 863         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 864                     "Dropping record `%s', does not match desired name `%s'\n",
 865                     rec->name,
 866                     rh->ac_tail->label);
 867         skip++;
 868         continue;
 869       }
 870       rd[i - skip].record_type = rec->type;
 871       rd[i - skip].expiration_time = rec->expiration_time.abs_value_us;
 872       switch (rec->type)
 873       {
 874       case GNUNET_DNSPARSER_TYPE_A:
 875         if (rec->data.raw.data_len != sizeof (struct in_addr))
 876         {
 877           GNUNET_break_op (0);
 878           skip++;
 879           continue;
 880         }
 881         rd[i - skip].data_size = rec->data.raw.data_len;
 882         rd[i - skip].data = rec->data.raw.data;
 883         break;
 884       case GNUNET_DNSPARSER_TYPE_AAAA:
 885         if (rec->data.raw.data_len != sizeof (struct in6_addr))
 886         {
 887           GNUNET_break_op (0);
 888           skip++;
 889           continue;
 890         }
 891         rd[i - skip].data_size = rec->data.raw.data_len;
 892         rd[i - skip].data = rec->data.raw.data;
 893         break;
 894       case GNUNET_DNSPARSER_TYPE_CNAME:
 895       case GNUNET_DNSPARSER_TYPE_PTR:
 896       case GNUNET_DNSPARSER_TYPE_NS:
 897         buf_start = buf_off;
 898         if (GNUNET_OK !=
 899             GNUNET_DNSPARSER_builder_add_name (buf,
 900                                                sizeof (buf),
 901                                                &buf_off,
 902                                                rec->data.hostname))
 903         {
 904           GNUNET_break (0);
 905           skip++;
 906           continue;
 907         }
 908         rd[i - skip].data_size = buf_off - buf_start;
 909         rd[i - skip].data = &buf[buf_start];
 910         break;
 911       case GNUNET_DNSPARSER_TYPE_SOA:
 912         buf_start = buf_off;
 913         if (GNUNET_OK !=
 914             GNUNET_DNSPARSER_builder_add_soa (buf,
 915                                                sizeof (buf),
 916                                                &buf_off,
 917                                                rec->data.soa))
 918         {
 919           GNUNET_break (0);
 920           skip++;
 921           continue;
 922         }
 923         rd[i - skip].data_size = buf_off - buf_start;
 924         rd[i - skip].data = &buf[buf_start];
 925         break;
 926       case GNUNET_DNSPARSER_TYPE_MX:
 927         buf_start = buf_off;
 928         if (GNUNET_OK !=
 929             GNUNET_DNSPARSER_builder_add_mx (buf,
 930                                              sizeof (buf),
 931                                              &buf_off,
 932                                              rec->data.mx))
 933         {
 934           GNUNET_break (0);
 935           skip++;
 936           continue;
 937         }
 938         rd[i - skip].data_size = buf_off - buf_start;
 939         rd[i - skip].data = &buf[buf_start];
 940         break;
 941       case GNUNET_DNSPARSER_TYPE_SRV:
 942         buf_start = buf_off;
 943         if (GNUNET_OK !=
 944             GNUNET_DNSPARSER_builder_add_srv (buf,
 945                                               sizeof (buf),
 946                                               &buf_off,
 947                                               rec->data.srv))
 948         {
 949           GNUNET_break (0);
 950           skip++;
 951           continue;
 952         }
 953         rd[i - skip].data_size = buf_off - buf_start;
 954         rd[i - skip].data = &buf[buf_start];
 955         break;
 956       default:
 957         GNUNET_log (GNUNET_ERROR_TYPE_INFO,
 958                     _("Skipping record of unsupported type %d\n"),
 959                     rec->type);
 960         skip++;
 961         continue;
 962       }
 963     }
 964     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 965                 "Returning DNS response for `%s' with %u answers\n",
 966                 rh->ac_tail->label,
 967                 (unsigned int) p->num_answers);
 968     rh->proc (rh->proc_cls, rd_count - skip, rd);
 969     GNS_resolver_lookup_cancel (rh);
 970   }
 971   GNUNET_DNSPARSER_free_packet (p);
 972 }
 973
 974
 975 /**
 976  * Perform recursive DNS resolution.  Asks the given DNS resolver to
 977  * resolve "rh->dns_name", possibly recursively proceeding following
 978  * NS delegations, CNAMES, etc., until 'rh->loop_limiter' bounds us or
 979  * we find the answer.
 980  *
 981  * @param rh resolution information
 982  */
 983 static void
 984 recursive_dns_resolution (struct GNS_ResolverHandle *rh)
 985 {
 986   struct AuthorityChain *ac;
 987   socklen_t sa_len;
 988   struct GNUNET_DNSPARSER_Query *query;
 989   struct GNUNET_DNSPARSER_Packet *p;
 990   char *dns_request;
 991   size_t dns_request_length;
 992
 993   ac = rh->ac_tail;
 994   GNUNET_assert (NULL != ac);
 995   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
 996               "Starting DNS lookup for `%s'\n",
 997               ac->label);
 998   GNUNET_assert (GNUNET_NO == ac->gns_authority);
 999   switch (((const struct sockaddr *) &ac->authority_info.dns_authority.dns_ip)->sa_family)
1000   {
1001   case AF_INET:
1002     sa_len = sizeof (struct sockaddr_in);
1003     break;
1004   case AF_INET6:
1005     sa_len = sizeof (struct sockaddr_in6);
1006     break;
1007   default:
1008     GNUNET_break (0);
1009     rh->proc (rh->proc_cls, 0, NULL);
1010     GNS_resolver_lookup_cancel (rh);
1011     return;
1012   }
1013   query = GNUNET_new (struct GNUNET_DNSPARSER_Query);
1014   query->name = GNUNET_strdup (ac->label);
1015   query->type = rh->record_type;
1016   query->dns_traffic_class = GNUNET_TUN_DNS_CLASS_INTERNET;
1017   p = GNUNET_new (struct GNUNET_DNSPARSER_Packet);
1018   p->queries = query;
1019   p->num_queries = 1;
1020   p->id = (uint16_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
1021                                                UINT16_MAX);
1022   p->flags.opcode = GNUNET_TUN_DNS_OPCODE_QUERY;
1023   p->flags.recursion_desired = 1;
1024   if (GNUNET_OK !=
1025       GNUNET_DNSPARSER_pack (p, 1024, &dns_request, &dns_request_length))
1026   {
1027     GNUNET_break (0);
1028     rh->proc (rh->proc_cls, 0, NULL);
1029     GNS_resolver_lookup_cancel (rh);
1030   }
1031   else
1032   {
1033     rh->dns_request = GNUNET_DNSSTUB_resolve (dns_handle,
1034                                               (const struct sockaddr *) &ac->authority_info.dns_authority.dns_ip,
1035                                               sa_len,
1036                                               dns_request,
1037                                               dns_request_length,
1038                                               &dns_result_parser,
1039                                               rh);
1040     rh->task_id = GNUNET_SCHEDULER_add_delayed (DNS_LOOKUP_TIMEOUT,
1041                                                 &fail_resolution,
1042                                                 rh);
1043   }
1044   GNUNET_free (dns_request);
1045   GNUNET_DNSPARSER_free_packet (p);
1046 }
1047
1048
1049 /**
1050  * We encountered a CNAME record during our resolution.
1051  * Merge it into our chain.
1052  *
1053  * @param rh resolution we are performing
1054  * @param cname value of the cname record we got for the current
1055  *        authority chain tail
1056  */
1057 static void
1058 handle_gns_cname_result (struct GNS_ResolverHandle *rh,
1059                          const char *cname)
1060 {
1061   size_t nlen;
1062   char *res;
1063   struct AuthorityChain *ac;
1064
1065   nlen = strlen (cname);
1066   if ( (nlen > 2) &&
1067        (0 == strcmp (".+",
1068                      &cname[nlen - 2])) )
1069   {
1070     /* CNAME resolution continues relative to current domain */
1071     if (0 == rh->name_resolution_pos)
1072     {
1073       res = GNUNET_strndup (cname, nlen - 2);
1074       rh->name_resolution_pos = nlen - 2;
1075     }
1076     else
1077     {
1078       GNUNET_asprintf (&res,
1079                        "%.*s.%.*s",
1080                        (int) rh->name_resolution_pos,
1081                        rh->name,
1082                        (int) (nlen - 2),
1083                        cname);
1084       rh->name_resolution_pos = strlen (res);
1085     }
1086     GNUNET_free (rh->name);
1087     rh->name = res;
1088     ac = GNUNET_new (struct AuthorityChain);
1089     ac->rh = rh;
1090     ac->gns_authority = GNUNET_YES;
1091     ac->authority_info.gns_authority = rh->ac_tail->authority_info.gns_authority;
1092     ac->label = resolver_lookup_get_next_label (rh);
1093     ac->suggested_shortening_label = NULL;
1094     ac->shortening_started = GNUNET_NO;
1095     /* add AC to tail */
1096     GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1097                                       rh->ac_tail,
1098                                       ac);
1099     rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1100                                             rh);
1101     return;
1102   }
1103   /* name is absolute, start from the beginning */
1104   GNUNET_free (rh->name);
1105   rh->name = GNUNET_strdup (cname);
1106   start_resolver_lookup (rh);
1107 }
1108
1109
1110 /**
1111  * Process a records that were decrypted from a block.
1112  *
1113  * @param cls closure with the 'struct GNS_ResolverHandle'
1114  * @param rd_count number of entries in @a rd array
1115  * @param rd array of records with data to store
1116  */
1117 static void
1118 handle_gns_resolution_result (void *cls,
1119                               unsigned int rd_count,
1120                               const struct GNUNET_GNSRECORD_Data *rd);
1121
1122
1123 /**
1124  * Callback invoked from the VPN service once a redirection is
1125  * available.  Provides the IP address that can now be used to
1126  * reach the requested destination.  Replaces the "VPN" record
1127  * with the respective A/AAAA record and continues processing.
1128  *
1129  * @param cls closure
1130  * @param af address family, AF_INET or AF_INET6; AF_UNSPEC on error;
1131  *                will match 'result_af' from the request
1132  * @param address IP address (struct in_addr or struct in_addr6, depending on 'af')
1133  *                that the VPN allocated for the redirection;
1134  *                traffic to this IP will now be redirected to the
1135  *                specified target peer; NULL on error
1136  */
1137 static void
1138 vpn_allocation_cb (void *cls,
1139                    int af,
1140                    const void *address)
1141 {
1142   struct VpnContext *vpn_ctx = cls;
1143   struct GNS_ResolverHandle *rh = vpn_ctx->rh;
1144   struct GNUNET_GNSRECORD_Data rd[vpn_ctx->rd_count];
1145   unsigned int i;
1146
1147   vpn_ctx->vpn_request = NULL;
1148   rh->vpn_ctx = NULL;
1149   GNUNET_assert (GNUNET_OK ==
1150                  GNUNET_GNSRECORD_records_deserialize (vpn_ctx->rd_data_size,
1151                                                        vpn_ctx->rd_data,
1152                                                        vpn_ctx->rd_count,
1153                                                        rd));
1154   for (i=0;i<vpn_ctx->rd_count;i++)
1155   {
1156     if (GNUNET_GNSRECORD_TYPE_VPN == rd[i].record_type)
1157     {
1158       switch (af)
1159       {
1160       case AF_INET:
1161         rd[i].record_type = GNUNET_DNSPARSER_TYPE_A;
1162         rd[i].data_size = sizeof (struct in_addr);
1163         rd[i].expiration_time = GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT).abs_value_us;
1164         rd[i].flags = 0;
1165         rd[i].data = address;
1166         break;
1167       case AF_INET6:
1168         rd[i].record_type = GNUNET_DNSPARSER_TYPE_AAAA;
1169         rd[i].expiration_time = GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT).abs_value_us;
1170         rd[i].flags = 0;
1171         rd[i].data = address;
1172         rd[i].data_size = sizeof (struct in6_addr);
1173         break;
1174       default:
1175         GNUNET_assert (0);
1176       }
1177       break;
1178     }
1179   }
1180   GNUNET_assert (i < vpn_ctx->rd_count);
1181   handle_gns_resolution_result (rh,
1182                                 vpn_ctx->rd_count,
1183                                 rd);
1184   GNUNET_free (vpn_ctx->rd_data);
1185   GNUNET_free (vpn_ctx);
1186 }
1187
1188
1189 /**
1190  * We've resolved the IP address for the DNS resolver to use
1191  * after encountering a GNS2DNS record.
1192  *
1193  * TODO: Right now we only foward the request to ONE DNS resolver,
1194  * even if we get multiple IP addresses back; a correct implementation
1195  * should try all DNS resolvers.
1196  *
1197  * @param cls the `struct GNS_ResolverHandle` where we encountered
1198  *            the GNS2DNS record
1199  * @param rd_count number of records in @a rd
1200  * @param rd addresses for the DNS resolver  (presumably)
1201  */
1202 static void
1203 handle_gns2dns_result (void *cls,
1204                        unsigned int rd_count,
1205                        const struct GNUNET_GNSRECORD_Data *rd)
1206 {
1207   struct GNS_ResolverHandle *rh = cls;
1208   struct AuthorityChain *ac;
1209   unsigned int j;
1210   struct sockaddr *sa;
1211   struct sockaddr_in v4;
1212   struct sockaddr_in6 v6;
1213   size_t sa_len;
1214
1215   /* find suitable A/AAAA record */
1216   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1217               "Received %u results for IP address of DNS server for GNS2DNS transition\n",
1218               rd_count);
1219   /* enable cleanup of 'rh' handle that comes next... */
1220   GNUNET_CONTAINER_DLL_insert (rlh_head,
1221                                rlh_tail,
1222                                rh->g2dc->rh);
1223   rh->g2dc->rh = NULL;
1224   sa = NULL;
1225   sa_len = 0;
1226   for (j=0;j<rd_count;j++)
1227   {
1228     switch (rd[j].record_type)
1229     {
1230     case GNUNET_DNSPARSER_TYPE_A:
1231       if (sizeof (struct in_addr) != rd[j].data_size)
1232       {
1233         GNUNET_break_op (0);
1234         rh->proc (rh->proc_cls, 0, NULL);
1235         GNS_resolver_lookup_cancel (rh);
1236         return;
1237       }
1238       /* FIXME: might want to check if we support IPv4 here,
1239          and otherwise skip this one and hope we find another */
1240       memset (&v4, 0, sizeof (v4));
1241       sa_len = sizeof (v4);
1242       v4.sin_family = AF_INET;
1243       v4.sin_port = htons (53);
1244 #if HAVE_SOCKADDR_IN_SIN_LEN
1245       v4.sin_len = (u_char) sa_len;
1246 #endif
1247       memcpy (&v4.sin_addr,
1248               rd[j].data,
1249               sizeof (struct in_addr));
1250       sa = (struct sockaddr *) &v4;
1251       break;
1252     case GNUNET_DNSPARSER_TYPE_AAAA:
1253       if (sizeof (struct in6_addr) != rd[j].data_size)
1254       {
1255         GNUNET_break_op (0);
1256         rh->proc (rh->proc_cls, 0, NULL);
1257         GNS_resolver_lookup_cancel (rh);
1258         return;
1259       }
1260       /* FIXME: might want to check if we support IPv6 here,
1261          and otherwise skip this one and hope we find another */
1262       memset (&v6, 0, sizeof (v6));
1263       sa_len = sizeof (v6);
1264       v6.sin6_family = AF_INET6;
1265       v6.sin6_port = htons (53);
1266 #if HAVE_SOCKADDR_IN_SIN_LEN
1267       v6.sin6_len = (u_char) sa_len;
1268 #endif
1269       memcpy (&v6.sin6_addr,
1270               rd[j].data,
1271               sizeof (struct in6_addr));
1272       sa = (struct sockaddr *) &v6;
1273       break;
1274     default:
1275       break;
1276     }
1277     if (NULL != sa)
1278       break;
1279   }
1280   if (NULL == sa)
1281   {
1282     /* we cannot continue; NS without A/AAAA */
1283     rh->proc (rh->proc_cls, 0, NULL);
1284     GNS_resolver_lookup_cancel (rh);
1285     return;
1286   }
1287   /* expand authority chain */
1288   ac = GNUNET_new (struct AuthorityChain);
1289   ac->rh = rh;
1290   strcpy (ac->authority_info.dns_authority.name,
1291           rh->g2dc->ns);
1292   memcpy (&ac->authority_info.dns_authority.dns_ip,
1293           sa,
1294           sa_len);
1295   /* for DNS recursion, the label is the full DNS name,
1296      created from the remainder of the GNS name and the
1297      name in the NS record */
1298   GNUNET_asprintf (&ac->label,
1299                    "%.*s%s%s",
1300                    (int) rh->name_resolution_pos,
1301                    rh->name,
1302                    (0 != rh->name_resolution_pos) ? "." : "",
1303                    rh->g2dc->ns);
1304   GNUNET_free (rh->g2dc->ns);
1305   GNUNET_free (rh->g2dc);
1306   rh->g2dc = NULL;
1307   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1308               "Will continue resolution using DNS server `%s' to resolve `%s'\n",
1309               GNUNET_a2s (sa, sa_len),
1310               ac->label);
1311   GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1312                                     rh->ac_tail,
1313                                     ac);
1314   if (strlen (ac->label) > GNUNET_DNSPARSER_MAX_NAME_LENGTH)
1315   {
1316     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1317                 _("GNS lookup resulted in DNS name that is too long (`%s')\n"),
1318                 ac->label);
1319     rh->proc (rh->proc_cls, 0, NULL);
1320     GNS_resolver_lookup_cancel (rh);
1321     return;
1322   }
1323   /* recurse */
1324   rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1325                                           rh);
1326 }
1327
1328
1329 /**
1330  * Process a records that were decrypted from a block.
1331  *
1332  * @param cls closure with the `struct GNS_ResolverHandle`
1333  * @param rd_count number of entries in @a rd array
1334  * @param rd array of records with data to store
1335  */
1336 static void
1337 handle_gns_resolution_result (void *cls,
1338                               unsigned int rd_count,
1339                               const struct GNUNET_GNSRECORD_Data *rd)
1340 {
1341   struct GNS_ResolverHandle *rh = cls;
1342   struct AuthorityChain *ac;
1343   struct AuthorityChain *shorten_ac;
1344   unsigned int i;
1345   char *cname;
1346   struct VpnContext *vpn_ctx;
1347   const struct GNUNET_TUN_GnsVpnRecord *vpn;
1348   const char *vname;
1349   struct GNUNET_HashCode vhash;
1350   int af;
1351   char scratch[UINT16_MAX];
1352   size_t scratch_off;
1353   size_t scratch_start;
1354   size_t off;
1355   struct GNUNET_GNSRECORD_Data rd_new[rd_count];
1356   unsigned int rd_off;
1357
1358   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
1359               "Resolution succeeded for `%s' in zone %s, got %u records\n",
1360               rh->ac_tail->label,
1361               GNUNET_GNSRECORD_z2s (&rh->ac_tail->authority_info.gns_authority),
1362               rd_count);
1363   if (0 == rh->name_resolution_pos)
1364   {
1365     /* top-level match, are we done yet? */
1366     if ( (rd_count > 0) &&
1367          (GNUNET_DNSPARSER_TYPE_CNAME == rd[0].record_type) &&
1368          (GNUNET_DNSPARSER_TYPE_CNAME != rh->record_type) )
1369     {
1370       off = 0;
1371       cname = GNUNET_DNSPARSER_parse_name (rd[0].data,
1372                                            rd[0].data_size,
1373                                            &off);
1374       if ( (NULL == cname) ||
1375            (off != rd[0].data_size) )
1376       {
1377         GNUNET_break_op (0);
1378         rh->proc (rh->proc_cls, 0, NULL);
1379         GNS_resolver_lookup_cancel (rh);
1380         GNUNET_free_non_null (cname);
1381         return;
1382       }
1383       handle_gns_cname_result (rh,
1384                                cname);
1385       GNUNET_free (cname);
1386       return;
1387     }
1388     /* If A/AAAA was requested, but we got a VPN
1389        record, we convert it to A/AAAA using GNUnet VPN */
1390     if ( (GNUNET_DNSPARSER_TYPE_A == rh->record_type) ||
1391          (GNUNET_DNSPARSER_TYPE_AAAA == rh->record_type) )
1392     {
1393       for (i=0;i<rd_count;i++)
1394       {
1395         switch (rd[i].record_type)
1396         {
1397         case GNUNET_GNSRECORD_TYPE_VPN:
1398           {
1399             af = (GNUNET_DNSPARSER_TYPE_A == rh->record_type) ? AF_INET : AF_INET6;
1400             if (sizeof (struct GNUNET_TUN_GnsVpnRecord) >
1401                 rd[i].data_size)
1402             {
1403               GNUNET_break_op (0);
1404               rh->proc (rh->proc_cls, 0, NULL);
1405               GNS_resolver_lookup_cancel (rh);
1406               return;
1407             }
1408             vpn = (const struct GNUNET_TUN_GnsVpnRecord *) rd[i].data;
1409             vname = (const char *) &vpn[1];
1410             if ('\0' != vname[rd[i].data_size - 1 - sizeof (struct GNUNET_TUN_GnsVpnRecord)])
1411             {
1412               GNUNET_break_op (0);
1413               rh->proc (rh->proc_cls, 0, NULL);
1414               GNS_resolver_lookup_cancel (rh);
1415               return;
1416             }
1417             GNUNET_TUN_service_name_to_hash (vname,
1418                                              &vhash);
1419             GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1420                         "Attempting VPN allocation for %s-%s (AF: %d, proto %d)\n",
1421                         GNUNET_i2s (&vpn->peer),
1422                         vname,
1423                         (int) af,
1424                         (int) ntohs (vpn->proto));
1425             vpn_ctx = GNUNET_new (struct VpnContext);
1426             rh->vpn_ctx = vpn_ctx;
1427             vpn_ctx->rh = rh;
1428             vpn_ctx->rd_data_size = GNUNET_GNSRECORD_records_get_size (rd_count,
1429                                                                        rd);
1430             vpn_ctx->rd_data = GNUNET_malloc (vpn_ctx->rd_data_size);
1431             vpn_ctx->rd_count = rd_count;
1432             GNUNET_assert (vpn_ctx->rd_data_size ==
1433                            GNUNET_GNSRECORD_records_serialize (rd_count,
1434                                                                rd,
1435                                                                vpn_ctx->rd_data_size,
1436                                                                vpn_ctx->rd_data));
1437             vpn_ctx->vpn_request = GNUNET_VPN_redirect_to_peer (vpn_handle,
1438                                                                 af,
1439                                                                 ntohs (vpn->proto),
1440                                                                 &vpn->peer,
1441                                                                 &vhash,
1442                                                                 GNUNET_TIME_relative_to_absolute (VPN_TIMEOUT),
1443                                                                 &vpn_allocation_cb,
1444                                                                 vpn_ctx);
1445             return;
1446           }
1447         case GNUNET_GNSRECORD_TYPE_GNS2DNS:
1448           {
1449             /* delegation to DNS */
1450             GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1451                         "Found GNS2DNS record, delegating to DNS!\n");
1452             goto do_recurse;
1453           }
1454         default:
1455           break;
1456         } /* end: switch */
1457       } /* end: for rd */
1458     } /* end: name_resolution_pos */
1459     /* convert relative names in record values to absolute names,
1460        using 'scratch' array for memory allocations */
1461     scratch_off = 0;
1462     rd_off = 0;
1463     shorten_ac = rh->ac_tail;
1464     for (i=0;i<rd_count;i++)
1465     {
1466       rd_new[rd_off] = rd[i];
1467       /* Check if the embedded name(s) end in "+", and if so,
1468          replace the "+" with the zone at "ac_tail", changing the name
1469          to a ".zkey".  The name is allocated on the 'scratch' array,
1470          so we can free it afterwards. */
1471       switch (rd[i].record_type)
1472       {
1473       case GNUNET_DNSPARSER_TYPE_CNAME:
1474         {
1475           char *cname;
1476
1477           off = 0;
1478           cname = GNUNET_DNSPARSER_parse_name (rd[i].data,
1479                                                rd[i].data_size,
1480                                                &off);
1481           if ( (NULL == cname) ||
1482                (off != rd[i].data_size) )
1483           {
1484             GNUNET_break_op (0); /* record not well-formed */
1485           }
1486           else
1487           {
1488             cname = translate_dot_plus (rh, cname);
1489             GNUNET_break (NULL != cname);
1490             scratch_start = scratch_off;
1491             if (GNUNET_OK !=
1492                 GNUNET_DNSPARSER_builder_add_name (scratch,
1493                                                    sizeof (scratch),
1494                                                    &scratch_off,
1495                                                    cname))
1496             {
1497               GNUNET_break (0);
1498             }
1499             else
1500             {
1501               rd_new[rd_off].data = &scratch[scratch_start];
1502               rd_new[rd_off].data_size = scratch_off - scratch_start;
1503               rd_off++;
1504             }
1505           }
1506           GNUNET_free_non_null (cname);
1507         }
1508         break;
1509       case GNUNET_DNSPARSER_TYPE_SOA:
1510         {
1511           struct GNUNET_DNSPARSER_SoaRecord *soa;
1512
1513           off = 0;
1514           soa = GNUNET_DNSPARSER_parse_soa (rd[i].data,
1515                                             rd[i].data_size,
1516                                             &off);
1517           if ( (NULL == soa) ||
1518                (off != rd[i].data_size) )
1519           {
1520             GNUNET_break_op (0); /* record not well-formed */
1521           }
1522           else
1523           {
1524             soa->mname = translate_dot_plus (rh, soa->mname);
1525             soa->rname = translate_dot_plus (rh, soa->rname);
1526             scratch_start = scratch_off;
1527             if (GNUNET_OK !=
1528                 GNUNET_DNSPARSER_builder_add_soa (scratch,
1529                                                   sizeof (scratch),
1530                                                   &scratch_off,
1531                                                   soa))
1532             {
1533               GNUNET_break (0);
1534             }
1535             else
1536             {
1537               rd_new[rd_off].data = &scratch[scratch_start];
1538               rd_new[rd_off].data_size = scratch_off - scratch_start;
1539               rd_off++;
1540             }
1541           }
1542           if (NULL != soa)
1543             GNUNET_DNSPARSER_free_soa (soa);
1544         }
1545         break;
1546       case GNUNET_DNSPARSER_TYPE_MX:
1547         {
1548           struct GNUNET_DNSPARSER_MxRecord *mx;
1549
1550           off = 0;
1551           mx = GNUNET_DNSPARSER_parse_mx (rd[i].data,
1552                                           rd[i].data_size,
1553                                           &off);
1554           if ( (NULL == mx) ||
1555                (off != rd[i].data_size) )
1556           {
1557             GNUNET_break_op (0); /* record not well-formed */
1558           }
1559           else
1560           {
1561             mx->mxhost = translate_dot_plus (rh, mx->mxhost);
1562             scratch_start = scratch_off;
1563             if (GNUNET_OK !=
1564                 GNUNET_DNSPARSER_builder_add_mx (scratch,
1565                                                  sizeof (scratch),
1566                                                  &scratch_off,
1567                                                  mx))
1568             {
1569               GNUNET_break (0);
1570             }
1571             else
1572             {
1573               rd_new[rd_off].data = &scratch[scratch_start];
1574               rd_new[rd_off].data_size = scratch_off - scratch_start;
1575               rd_off++;
1576             }
1577           }
1578           if (NULL != mx)
1579             GNUNET_DNSPARSER_free_mx (mx);
1580         }
1581         break;
1582       case GNUNET_DNSPARSER_TYPE_SRV:
1583         {
1584           struct GNUNET_DNSPARSER_SrvRecord *srv;
1585
1586           off = 0;
1587           /* FIXME: passing rh->name here is is not necessarily what we want
1588              (SRV support not finished) */
1589           srv = GNUNET_DNSPARSER_parse_srv (rh->name,
1590                                             rd[i].data,
1591                                             rd[i].data_size,
1592                                             &off);
1593           if ( (NULL == srv) ||
1594                (off != rd[i].data_size) )
1595           {
1596             GNUNET_break_op (0); /* record not well-formed */
1597           }
1598           else
1599           {
1600             srv->domain_name = translate_dot_plus (rh, srv->domain_name);
1601             srv->target = translate_dot_plus (rh, srv->target);
1602             scratch_start = scratch_off;
1603             if (GNUNET_OK !=
1604                 GNUNET_DNSPARSER_builder_add_srv (scratch,
1605                                                   sizeof (scratch),
1606                                                   &scratch_off,
1607                                                   srv))
1608             {
1609               GNUNET_break (0);
1610             }
1611             else
1612             {
1613               rd_new[rd_off].data = &scratch[scratch_start];
1614               rd_new[rd_off].data_size = scratch_off - scratch_start;
1615               rd_off++;
1616             }
1617           }
1618           if (NULL != srv)
1619             GNUNET_DNSPARSER_free_srv (srv);
1620         }
1621         break;
1622
1623       case GNUNET_GNSRECORD_TYPE_NICK:
1624         {
1625           const char *nick;
1626           nick = rd[i].data;
1627           if ((rd[i].data_size > 0) &&
1628               (nick[rd[i].data_size -1] != '\0'))
1629           {
1630             GNUNET_break_op (0);
1631             break;
1632           }
1633           if (NULL == shorten_ac->suggested_shortening_label)
1634             shorten_ac->suggested_shortening_label = GNUNET_strdup (nick);
1635           break;
1636         }
1637       case GNUNET_GNSRECORD_TYPE_PKEY:
1638         {
1639           struct GNUNET_CRYPTO_EcdsaPublicKey pub;
1640
1641           if (rd[i].data_size != sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey))
1642           {
1643             GNUNET_break_op (0);
1644             break;
1645           }
1646           memcpy (&pub, rd[i].data, rd[i].data_size);
1647           rd_off++;
1648           if (GNUNET_GNSRECORD_TYPE_PKEY != rh->record_type)
1649           {
1650             /* try to resolve "+" */
1651             struct AuthorityChain *ac;
1652
1653             ac = GNUNET_new (struct AuthorityChain);
1654             ac->rh = rh;
1655             ac->gns_authority = GNUNET_YES;
1656             ac->authority_info.gns_authority = pub;
1657             ac->label = GNUNET_strdup (GNUNET_GNS_MASTERZONE_STR);
1658             ac->suggested_shortening_label = NULL;
1659             ac->shortening_started = GNUNET_NO;
1660             GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1661                                               rh->ac_tail,
1662                                               ac);
1663             rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1664                                                     rh);
1665             return;
1666           }
1667         }
1668         break;
1669       case GNUNET_GNSRECORD_TYPE_GNS2DNS:
1670         {
1671           /* delegation to DNS */
1672           GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1673                       "Found GNS2DNS record, delegating to DNS!\n");
1674           goto do_recurse;
1675         }
1676       default:
1677         rd_off++;
1678         break;
1679       } /* end: switch */
1680     } /* end: for rd_count */
1681
1682     /* trigger shortening */
1683     if ((NULL != rh->shorten_key) &&
1684         (NULL != shorten_ac) &&
1685         (GNUNET_NO == shorten_ac->shortening_started) &&
1686         (NULL != shorten_ac->suggested_shortening_label))
1687     {
1688         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1689                     "Start shortening for label `%s' based on nick `%s'\n",
1690                     shorten_ac->label,
1691                     shorten_ac->suggested_shortening_label);
1692         shorten_ac->shortening_started = GNUNET_YES;
1693         GNS_shorten_start (shorten_ac->label,
1694                          shorten_ac->suggested_shortening_label,
1695                          &shorten_ac->authority_info.gns_authority,
1696                          rh->shorten_key);
1697     }
1698
1699     /* yes, we are done, return result */
1700     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1701                 "Returning GNS response for `%s' with %u answers\n",
1702                 rh->ac_tail->label,
1703                 rd_off);
1704     rh->proc (rh->proc_cls, rd_off, rd_new);
1705     GNS_resolver_lookup_cancel (rh);
1706     return;
1707   }
1708  do_recurse:
1709   /* need to recurse, check if we can */
1710   for (i=0;i<rd_count;i++)
1711   {
1712     switch (rd[i].record_type)
1713     {
1714     case GNUNET_GNSRECORD_TYPE_PKEY:
1715       /* delegation to another zone */
1716       if (sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey) !=
1717           rd[i].data_size)
1718       {
1719         GNUNET_break_op (0);
1720         rh->proc (rh->proc_cls, 0, NULL);
1721         GNS_resolver_lookup_cancel (rh);
1722         return;
1723       }
1724       /* expand authority chain */
1725       ac = GNUNET_new (struct AuthorityChain);
1726       ac->rh = rh;
1727       ac->gns_authority = GNUNET_YES;
1728       ac->suggested_shortening_label = NULL;
1729       ac->shortening_started = GNUNET_NO;
1730       memcpy (&ac->authority_info.gns_authority,
1731               rd[i].data,
1732               sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey));
1733       ac->label = resolver_lookup_get_next_label (rh);
1734       /* add AC to tail */
1735       GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
1736                                         rh->ac_tail,
1737                                         ac);
1738       /* recurse */
1739       rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
1740                                               rh);
1741       return;
1742     case GNUNET_GNSRECORD_TYPE_GNS2DNS:
1743       {
1744         /* resolution continues within DNS */
1745         struct Gns2DnsContext *g2dc;
1746         char *ip;
1747         char *ns;
1748
1749         off = 0;
1750         ns = GNUNET_DNSPARSER_parse_name (rd[i].data,
1751                                           rd[i].data_size,
1752                                           &off);
1753         ip = GNUNET_DNSPARSER_parse_name (rd[i].data,
1754                                           rd[i].data_size,
1755                                           &off);
1756         if ( (NULL == ns) ||
1757              (NULL == ip) ||
1758              (off != rd[i].data_size) )
1759         {
1760           GNUNET_break_op (0);
1761           GNUNET_free_non_null (ns);
1762           GNUNET_free_non_null (ip);
1763           rh->proc (rh->proc_cls, 0, NULL);
1764           GNS_resolver_lookup_cancel (rh);
1765           return;
1766         }
1767         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1768                     "Resolving `%s' to determine IP address of DNS server for GNS2DNS transition\n",
1769                     ip);
1770         /* resolve 'ip' to determine the IP(s) of the DNS
1771            resolver to use */
1772         g2dc = GNUNET_new (struct Gns2DnsContext);
1773         g2dc->ns = ns;
1774         g2dc->rh = GNUNET_new (struct GNS_ResolverHandle);
1775         g2dc->rh->authority_zone = rh->ac_tail->authority_info.gns_authority;
1776         ip = translate_dot_plus (rh, ip);
1777         g2dc->rh->name = ip;
1778         g2dc->rh->name_resolution_pos = strlen (ip);
1779         g2dc->rh->proc = &handle_gns2dns_result;
1780         g2dc->rh->proc_cls = rh;
1781         g2dc->rh->record_type = GNUNET_GNSRECORD_TYPE_ANY;
1782         g2dc->rh->only_cached = GNUNET_NO;
1783         g2dc->rh->loop_limiter = rh->loop_limiter + 1;
1784         rh->g2dc = g2dc;
1785         start_resolver_lookup (g2dc->rh);
1786         return;
1787       }
1788     case GNUNET_DNSPARSER_TYPE_CNAME:
1789       {
1790         char *cname;
1791
1792         off = 0;
1793         cname = GNUNET_DNSPARSER_parse_name (rd[i].data,
1794                                              rd[i].data_size,
1795                                              &off);
1796         if ( (NULL == cname) ||
1797              (off != rd[i].data_size) )
1798         {
1799           GNUNET_break_op (0); /* record not well-formed */
1800           rh->proc (rh->proc_cls, 0, NULL);
1801           GNS_resolver_lookup_cancel (rh);
1802           GNUNET_free_non_null (cname);
1803           return;
1804         }
1805         handle_gns_cname_result (rh,
1806                                  cname);
1807         GNUNET_free (cname);
1808         return;
1809       }
1810       /* FIXME: handle DNAME */
1811     default:
1812       /* skip */
1813       break;
1814     }
1815   }
1816   GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1817               _("GNS lookup recursion failed (no delegation record found)\n"));
1818   rh->proc (rh->proc_cls, 0, NULL);
1819   GNS_resolver_lookup_cancel (rh);
1820 }
1821
1822
1823 /**
1824  * Function called once the namestore has completed the request for
1825  * caching a block.
1826  *
1827  * @param cls closure with the `struct CacheOps`
1828  * @param success #GNUNET_OK on success
1829  * @param emsg error message
1830  */
1831 static void
1832 namecache_cache_continuation (void *cls,
1833                               int32_t success,
1834                               const char *emsg)
1835 {
1836   struct CacheOps *co = cls;
1837
1838   co->namecache_qe_cache = NULL;
1839   if (NULL != emsg)
1840     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1841                 _("Failed to cache GNS resolution: %s\n"),
1842                 emsg);
1843   GNUNET_CONTAINER_DLL_remove (co_head,
1844                                co_tail,
1845                                co);
1846   GNUNET_free (co);
1847 }
1848
1849
1850 /**
1851  * Iterator called on each result obtained for a DHT
1852  * operation that expects a reply
1853  *
1854  * @param cls closure with the `struct GNS_ResolverHandle`
1855  * @param exp when will this value expire
1856  * @param key key of the result
1857  * @param get_path peers on reply path (or NULL if not recorded)
1858  *                 [0] = datastore's first neighbor, [length - 1] = local peer
1859  * @param get_path_length number of entries in @a get_path
1860  * @param put_path peers on the PUT path (or NULL if not recorded)
1861  *                 [0] = origin, [length - 1] = datastore
1862  * @param put_path_length number of entries in @a put_path
1863  * @param type type of the result
1864  * @param size number of bytes in data
1865  * @param data pointer to the result data
1866  */
1867 static void
1868 handle_dht_response (void *cls,
1869                      struct GNUNET_TIME_Absolute exp,
1870                      const struct GNUNET_HashCode *key,
1871                      const struct GNUNET_PeerIdentity *get_path,
1872                      unsigned int get_path_length,
1873                      const struct GNUNET_PeerIdentity *put_path,
1874                      unsigned int put_path_length,
1875                      enum GNUNET_BLOCK_Type type,
1876                      size_t size, const void *data)
1877 {
1878   struct GNS_ResolverHandle *rh = cls;
1879   struct AuthorityChain *ac = rh->ac_tail;
1880   const struct GNUNET_GNSRECORD_Block *block;
1881   struct CacheOps *co;
1882
1883   GNUNET_DHT_get_stop (rh->get_handle);
1884   rh->get_handle = NULL;
1885   GNUNET_CONTAINER_heap_remove_node (rh->dht_heap_node);
1886   rh->dht_heap_node = NULL;
1887   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1888               "Handling response from the DHT\n");
1889   if (size < sizeof (struct GNUNET_GNSRECORD_Block))
1890   {
1891     /* how did this pass DHT block validation!? */
1892     GNUNET_break (0);
1893     rh->proc (rh->proc_cls, 0, NULL);
1894     GNS_resolver_lookup_cancel (rh);
1895     return;
1896   }
1897   block = data;
1898   if (size !=
1899       ntohl (block->purpose.size) +
1900       sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey) +
1901       sizeof (struct GNUNET_CRYPTO_EcdsaSignature))
1902   {
1903     /* how did this pass DHT block validation!? */
1904     GNUNET_break (0);
1905     rh->proc (rh->proc_cls, 0, NULL);
1906     GNS_resolver_lookup_cancel (rh);
1907     return;
1908   }
1909   if (GNUNET_OK !=
1910       GNUNET_GNSRECORD_block_decrypt (block,
1911                                       &ac->authority_info.gns_authority,
1912                                       ac->label,
1913                                       &handle_gns_resolution_result,
1914                                       rh))
1915   {
1916     GNUNET_break_op (0); /* block was ill-formed */
1917     rh->proc (rh->proc_cls, 0, NULL);
1918     GNS_resolver_lookup_cancel (rh);
1919     return;
1920   }
1921   if (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us)
1922   {
1923     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1924                 "Received expired block from the DHT, will not cache it.\n");
1925     return;
1926   }
1927   /* Cache well-formed blocks */
1928   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1929               "Caching response from the DHT in namecache\n");
1930   co = GNUNET_new (struct CacheOps);
1931   co->namecache_qe_cache = GNUNET_NAMECACHE_block_cache (namecache_handle,
1932                                                          block,
1933                                                          &namecache_cache_continuation,
1934                                                          co);
1935   GNUNET_CONTAINER_DLL_insert (co_head,
1936                                co_tail,
1937                                co);
1938 }
1939
1940
1941 /**
1942  * Initiate a DHT query for a set of GNS records.
1943  *
1944  * @param rh resolution handle
1945  * @param query key to use in the DHT lookup
1946  */
1947 static void
1948 start_dht_request (struct GNS_ResolverHandle *rh,
1949                    const struct GNUNET_HashCode *query)
1950 {
1951   struct GNS_ResolverHandle *rx;
1952
1953   GNUNET_assert (NULL == rh->get_handle);
1954   rh->get_handle = GNUNET_DHT_get_start (dht_handle,
1955                                          GNUNET_BLOCK_TYPE_GNS_NAMERECORD,
1956                                          query,
1957                                          DHT_GNS_REPLICATION_LEVEL,
1958                                          GNUNET_DHT_RO_DEMULTIPLEX_EVERYWHERE,
1959                                          NULL, 0,
1960                                          &handle_dht_response, rh);
1961   rh->dht_heap_node = GNUNET_CONTAINER_heap_insert (dht_lookup_heap,
1962                                                     rh,
1963                                                     GNUNET_TIME_absolute_get ().abs_value_us);
1964   if (GNUNET_CONTAINER_heap_get_size (dht_lookup_heap) > max_allowed_background_queries)
1965   {
1966     /* fail longest-standing DHT request */
1967     rx = GNUNET_CONTAINER_heap_peek (dht_lookup_heap);
1968     GNUNET_assert (NULL != rx);
1969     rx->proc (rx->proc_cls, 0, NULL);
1970     GNS_resolver_lookup_cancel (rx);
1971   }
1972 }
1973
1974
1975 /**
1976  * Process a records that were decrypted from a block that we
1977  * got from the namecache.  If the desired record type is not
1978  * included, we should query the DHT.  Otherwise, we should
1979  * simply call #handle_gns_resolution_result().
1980  *
1981  * @param cls closure with the `struct GNS_ResolverHandle`
1982  * @param rd_count number of entries in @a rd array
1983  * @param rd array of records with data to store
1984  */
1985 static void
1986 handle_gns_namecache_resolution_result (void *cls,
1987                                         unsigned int rd_count,
1988                                         const struct GNUNET_GNSRECORD_Data *rd)
1989 {
1990   struct GNS_ResolverHandle *rh = cls;
1991   unsigned int i;
1992   int found;
1993
1994   found = GNUNET_NO;
1995   for (i=0;i<rd_count;i++)
1996   {
1997     if (rd[i].record_type == rh->record_type)
1998     {
1999       found = GNUNET_YES;
2000       break;
2001     }
2002     switch (rd[i].record_type)
2003     {
2004     case GNUNET_GNSRECORD_TYPE_VPN:
2005       if ( (GNUNET_DNSPARSER_TYPE_A == rh->record_type) ||
2006            (GNUNET_DNSPARSER_TYPE_AAAA == rh->record_type) )
2007       {
2008         found = GNUNET_YES;
2009         break;
2010       }
2011       break;
2012     case GNUNET_DNSPARSER_TYPE_CNAME:
2013     case GNUNET_GNSRECORD_TYPE_PKEY:
2014     case GNUNET_GNSRECORD_TYPE_GNS2DNS:
2015       /* delegations always count as 'found' */
2016       found = GNUNET_YES;
2017       break;
2018     default:
2019       break;
2020     }
2021   }
2022   if (GNUNET_YES == found)
2023   {
2024     handle_gns_resolution_result (rh,
2025                                   rd_count,
2026                                   rd);
2027   }
2028   else
2029   {
2030     /* try DHT */
2031     struct AuthorityChain *ac = rh->ac_tail;
2032     const char *label = ac->label;
2033     const struct GNUNET_CRYPTO_EcdsaPublicKey *auth = &ac->authority_info.gns_authority;
2034     struct GNUNET_HashCode query;
2035
2036     GNUNET_GNSRECORD_query_from_public_key (auth,
2037                                             label,
2038                                             &query);
2039     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2040                 "Starting DHT lookup for `%s' in zone `%s' under key `%s'\n",
2041                 ac->label,
2042                 GNUNET_GNSRECORD_z2s (&ac->authority_info.gns_authority),
2043                 GNUNET_h2s (&query));
2044     start_dht_request (rh, &query);
2045   }
2046 }
2047
2048
2049 /**
2050  * Process a record that was stored in the namecache.
2051  *
2052  * @param cls closure with the `struct GNS_ResolverHandle`
2053  * @param block block that was stored in the namecache
2054  */
2055 static void
2056 handle_namecache_block_response (void *cls,
2057                                  const struct GNUNET_GNSRECORD_Block *block)
2058 {
2059   struct GNS_ResolverHandle *rh = cls;
2060   struct AuthorityChain *ac = rh->ac_tail;
2061   const char *label = ac->label;
2062   const struct GNUNET_CRYPTO_EcdsaPublicKey *auth = &ac->authority_info.gns_authority;
2063   struct GNUNET_HashCode query;
2064
2065   GNUNET_assert (NULL != rh->namecache_qe);
2066   rh->namecache_qe = NULL;
2067   if ( (GNUNET_NO == rh->only_cached) &&
2068        ( (NULL == block) ||
2069          (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us) ) )
2070   {
2071     /* namecache knows nothing; try DHT lookup */
2072     GNUNET_GNSRECORD_query_from_public_key (auth,
2073                                             label,
2074                                             &query);
2075     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2076                 "Starting DHT lookup for `%s' in zone `%s' under key `%s'\n",
2077                 ac->label,
2078                 GNUNET_GNSRECORD_z2s (&ac->authority_info.gns_authority),
2079                 GNUNET_h2s (&query));
2080     start_dht_request (rh, &query);
2081     return;
2082   }
2083
2084   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2085               "Received result from namecache for label `%s'\n",
2086               ac->label);
2087
2088   if ( (NULL == block) ||
2089        (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us) )
2090   {
2091     /* DHT not permitted and no local result, fail */
2092     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2093                 "Resolution failed for `%s' in zone %s (DHT lookup not permitted by configuration)\n",
2094                 ac->label,
2095                 GNUNET_GNSRECORD_z2s (&ac->authority_info.gns_authority));
2096     rh->proc (rh->proc_cls, 0, NULL);
2097     GNS_resolver_lookup_cancel (rh);
2098     return;
2099   }
2100   if (GNUNET_OK !=
2101       GNUNET_GNSRECORD_block_decrypt (block,
2102                                       auth,
2103                                       label,
2104                                       &handle_gns_namecache_resolution_result,
2105                                       rh))
2106   {
2107     GNUNET_break_op (0); /* block was ill-formed */
2108     /* try DHT instead */
2109     GNUNET_GNSRECORD_query_from_public_key (auth,
2110                                             label,
2111                                             &query);
2112     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2113                 "Starting DHT lookup for `%s' in zone `%s' under key `%s'\n",
2114                 ac->label,
2115                 GNUNET_GNSRECORD_z2s (&ac->authority_info.gns_authority),
2116                 GNUNET_h2s (&query));
2117     start_dht_request (rh, &query);
2118     return;
2119   }
2120 }
2121
2122
2123 /**
2124  * Lookup tail of our authority chain in the namecache.
2125  *
2126  * @param rh query we are processing
2127  */
2128 static void
2129 recursive_gns_resolution_namecache (struct GNS_ResolverHandle *rh)
2130 {
2131   struct AuthorityChain *ac = rh->ac_tail;
2132   struct GNUNET_HashCode query;
2133
2134   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2135               "Starting GNS resolution for `%s' in zone %s\n",
2136               ac->label,
2137               GNUNET_GNSRECORD_z2s (&ac->authority_info.gns_authority));
2138   GNUNET_GNSRECORD_query_from_public_key (&ac->authority_info.gns_authority,
2139                                           ac->label,
2140                                           &query);
2141   if (GNUNET_YES == use_cache)
2142   {
2143     rh->namecache_qe = GNUNET_NAMECACHE_lookup_block (namecache_handle,
2144                                                     &query,
2145                                                     &handle_namecache_block_response,
2146                                                     rh);
2147     GNUNET_assert (NULL != rh->namecache_qe);
2148   }
2149   else
2150   {
2151     start_dht_request (rh, &query);
2152   }
2153 }
2154
2155
2156 /**
2157  * Function called with the result from a revocation check.
2158  *
2159  * @param cls the `struct GNS_ResovlerHandle`
2160  * @param is_valid #GNUNET_YES if the zone was not yet revoked
2161  */
2162 static void
2163 handle_revocation_result (void *cls,
2164                           int is_valid)
2165 {
2166   struct GNS_ResolverHandle *rh = cls;
2167   struct AuthorityChain *ac = rh->ac_tail;
2168
2169   rh->rev_check = NULL;
2170   if (GNUNET_YES != is_valid)
2171   {
2172     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
2173                 _("Zone %s was revoked, resolution fails\n"),
2174                 GNUNET_GNSRECORD_z2s (&ac->authority_info.gns_authority));
2175     rh->proc (rh->proc_cls, 0, NULL);
2176     GNS_resolver_lookup_cancel (rh);
2177     return;
2178   }
2179   recursive_gns_resolution_namecache (rh);
2180 }
2181
2182
2183 /**
2184  * Perform revocation check on tail of our authority chain.
2185  *
2186  * @param rh query we are processing
2187  */
2188 static void
2189 recursive_gns_resolution_revocation (struct GNS_ResolverHandle *rh)
2190 {
2191   struct AuthorityChain *ac = rh->ac_tail;
2192
2193   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2194               "Starting revocation check for zone %s\n",
2195               GNUNET_GNSRECORD_z2s (&ac->authority_info.gns_authority));
2196   rh->rev_check = GNUNET_REVOCATION_query (cfg,
2197                                            &ac->authority_info.gns_authority,
2198                                            &handle_revocation_result,
2199                                            rh);
2200   GNUNET_assert (NULL != rh->rev_check);
2201 }
2202
2203
2204 /**
2205  * Task scheduled to continue with the resolution process.
2206  *
2207  * @param cls the `struct GNS_ResolverHandle` of the resolution
2208  * @param tc task context
2209  */
2210 static void
2211 recursive_resolution (void *cls,
2212                       const struct GNUNET_SCHEDULER_TaskContext *tc)
2213 {
2214   struct GNS_ResolverHandle *rh = cls;
2215
2216   rh->task_id = GNUNET_SCHEDULER_NO_TASK;
2217   if (MAX_RECURSION < rh->loop_limiter++)
2218   {
2219     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
2220                 "Encountered unbounded recursion resolving `%s'\n",
2221                 rh->name);
2222     rh->proc (rh->proc_cls, 0, NULL);
2223     GNS_resolver_lookup_cancel (rh);
2224     return;
2225   }
2226   if (GNUNET_YES == rh->ac_tail->gns_authority)
2227     recursive_gns_resolution_revocation (rh);
2228   else
2229     recursive_dns_resolution (rh);
2230 }
2231
2232
2233 /**
2234  * Begin the resolution process from 'name', starting with
2235  * the identification of the zone specified by 'name'.
2236  *
2237  * @param rh resolution to perform
2238  */
2239 static void
2240 start_resolver_lookup (struct GNS_ResolverHandle *rh)
2241 {
2242   struct AuthorityChain *ac;
2243   char *y;
2244   struct in_addr v4;
2245   struct in6_addr v6;
2246
2247   if (1 == inet_pton (AF_INET,
2248                       rh->name,
2249                       &v4))
2250   {
2251     /* name is IPv4 address, pretend it's an A record */
2252     struct GNUNET_GNSRECORD_Data rd;
2253
2254     rd.data = &v4;
2255     rd.data_size = sizeof (v4);
2256     rd.expiration_time = UINT64_MAX;
2257     rd.record_type = GNUNET_DNSPARSER_TYPE_A;
2258     rd.flags = 0;
2259     rh->proc (rh->proc_cls, 1, &rd);
2260     GNS_resolver_lookup_cancel (rh);
2261     return;
2262   }
2263   if (1 == inet_pton (AF_INET6,
2264                       rh->name,
2265                       &v6))
2266   {
2267     /* name is IPv6 address, pretend it's an AAAA record */
2268     struct GNUNET_GNSRECORD_Data rd;
2269
2270     rd.data = &v6;
2271     rd.data_size = sizeof (v6);
2272     rd.expiration_time = UINT64_MAX;
2273     rd.record_type = GNUNET_DNSPARSER_TYPE_AAAA;
2274     rd.flags = 0;
2275     rh->proc (rh->proc_cls, 1, &rd);
2276     GNS_resolver_lookup_cancel (rh);
2277     return;
2278   }
2279   if ( ( (GNUNET_YES == is_canonical (rh->name)) &&
2280          (0 != strcmp (GNUNET_GNS_TLD, rh->name)) ) ||
2281        ( (GNUNET_YES != is_gnu_tld (rh->name)) &&
2282          (GNUNET_YES != is_zkey_tld (rh->name)) ) )
2283   {
2284     /* use standard DNS lookup */
2285     int af;
2286
2287     switch (rh->record_type)
2288     {
2289     case GNUNET_DNSPARSER_TYPE_A:
2290       af = AF_INET;
2291       break;
2292     case GNUNET_DNSPARSER_TYPE_AAAA:
2293       af = AF_INET6;
2294       break;
2295     default:
2296       af = AF_UNSPEC;
2297       break;
2298     }
2299     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2300                 "Doing standard DNS lookup for `%s'\n",
2301                 rh->name);
2302     rh->std_resolve = GNUNET_RESOLVER_ip_get (rh->name,
2303                                               af,
2304                                               DNS_LOOKUP_TIMEOUT,
2305                                               &handle_dns_result,
2306                                               rh);
2307     return;
2308   }
2309   if (is_zkey_tld (rh->name))
2310   {
2311     /* Name ends with ".zkey", try to replace authority zone with zkey
2312        authority */
2313     GNUNET_free (resolver_lookup_get_next_label (rh)); /* will return "zkey" */
2314     y = resolver_lookup_get_next_label (rh); /* will return 'y' coordinate */
2315     if ( (NULL == y) ||
2316          (GNUNET_OK !=
2317           GNUNET_CRYPTO_ecdsa_public_key_from_string (y,
2318                                                       strlen (y),
2319                                                       &rh->authority_zone)) )
2320     {
2321       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
2322                   _("Hostname `%s' is not well-formed, resolution fails\n"),
2323                   rh->name);
2324       rh->task_id = GNUNET_SCHEDULER_add_now (&fail_resolution, rh);
2325     }
2326     GNUNET_free_non_null (y);
2327   }
2328   else
2329   {
2330     /* Name ends with ".gnu", eat ".gnu" and continue with resolution */
2331     GNUNET_free (resolver_lookup_get_next_label (rh));
2332   }
2333   ac = GNUNET_new (struct AuthorityChain);
2334   ac->rh = rh;
2335   ac->label = resolver_lookup_get_next_label (rh);
2336   ac->suggested_shortening_label = NULL;
2337   if (NULL == ac->label)
2338     /* name was just "gnu", so we default to label '+' */
2339     ac->label = GNUNET_strdup (GNUNET_GNS_MASTERZONE_STR);
2340   ac->gns_authority = GNUNET_YES;
2341   ac->authority_info.gns_authority = rh->authority_zone;
2342   GNUNET_CONTAINER_DLL_insert_tail (rh->ac_head,
2343                                     rh->ac_tail,
2344                                     ac);
2345   rh->task_id = GNUNET_SCHEDULER_add_now (&recursive_resolution,
2346                                           rh);
2347 }
2348
2349
2350 /**
2351  * Lookup of a record in a specific zone calls lookup result processor
2352  * on result.
2353  *
2354  * @param zone the zone to perform the lookup in
2355  * @param record_type the record type to look up
2356  * @param name the name to look up
2357  * @param shorten_key a private key for use with PSEU import (can be NULL)
2358  * @param only_cached #GNUNET_NO to only check locally not DHT for performance
2359  * @param proc the processor to call on result
2360  * @param proc_cls the closure to pass to @a proc
2361  * @return handle to cancel operation
2362  */
2363 struct GNS_ResolverHandle *
2364 GNS_resolver_lookup (const struct GNUNET_CRYPTO_EcdsaPublicKey *zone,
2365                      uint32_t record_type,
2366                      const char *name,
2367                      const struct GNUNET_CRYPTO_EcdsaPrivateKey *shorten_key,
2368                      int only_cached,
2369                      GNS_ResultProcessor proc, void *proc_cls)
2370 {
2371   struct GNS_ResolverHandle *rh;
2372
2373   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2374               (NULL == shorten_key)
2375               ? "Starting lookup for `%s' with shortening disabled\n"
2376               : "Starting lookup for `%s' with shortening enabled\n",
2377               name);
2378   rh = GNUNET_new (struct GNS_ResolverHandle);
2379   GNUNET_CONTAINER_DLL_insert (rlh_head,
2380                                rlh_tail,
2381                                rh);
2382   rh->authority_zone = *zone;
2383   rh->proc = proc;
2384   rh->proc_cls = proc_cls;
2385   rh->only_cached = only_cached;
2386   rh->record_type = record_type;
2387   rh->name = GNUNET_strdup (name);
2388   rh->name_resolution_pos = strlen (name);
2389   if (NULL != shorten_key)
2390   {
2391     rh->shorten_key = GNUNET_new (struct GNUNET_CRYPTO_EcdsaPrivateKey);
2392     *rh->shorten_key = *shorten_key;
2393   }
2394   start_resolver_lookup (rh);
2395   return rh;
2396 }
2397
2398
2399 /**
2400  * Cancel active resolution (i.e. client disconnected).
2401  *
2402  * @param rh resolution to abort
2403  */
2404 void
2405 GNS_resolver_lookup_cancel (struct GNS_ResolverHandle *rh)
2406 {
2407   struct DnsResult *dr;
2408   struct AuthorityChain *ac;
2409   struct VpnContext *vpn_ctx;
2410
2411   GNUNET_CONTAINER_DLL_remove (rlh_head,
2412                                rlh_tail,
2413                                rh);
2414   while (NULL != (ac = rh->ac_head))
2415   {
2416     GNUNET_CONTAINER_DLL_remove (rh->ac_head,
2417                                  rh->ac_tail,
2418                                  ac);
2419     GNUNET_free (ac->label);
2420     GNUNET_free_non_null (ac->suggested_shortening_label);
2421     GNUNET_free (ac);
2422   }
2423   if (NULL != rh->g2dc)
2424   {
2425     /* rh->g2dc->rh is NOT in the DLL yet, so to enable us
2426        using GNS_resolver_lookup_cancel here, we need to
2427        add it first... */
2428     if (NULL != rh->g2dc->rh)
2429     {
2430       GNUNET_CONTAINER_DLL_insert (rlh_head,
2431                                    rlh_tail,
2432                                    rh->g2dc->rh);
2433       GNS_resolver_lookup_cancel (rh->g2dc->rh);
2434       rh->g2dc->rh = NULL;
2435     }
2436     GNUNET_free (rh->g2dc->ns);
2437     GNUNET_free (rh->g2dc);
2438     rh->g2dc = NULL;
2439   }
2440   if (GNUNET_SCHEDULER_NO_TASK != rh->task_id)
2441   {
2442     GNUNET_SCHEDULER_cancel (rh->task_id);
2443     rh->task_id = GNUNET_SCHEDULER_NO_TASK;
2444   }
2445   if (NULL != rh->get_handle)
2446   {
2447     GNUNET_DHT_get_stop (rh->get_handle);
2448     rh->get_handle = NULL;
2449   }
2450   if (NULL != rh->dht_heap_node)
2451   {
2452     GNUNET_CONTAINER_heap_remove_node (rh->dht_heap_node);
2453     rh->dht_heap_node = NULL;
2454   }
2455   if (NULL != (vpn_ctx = rh->vpn_ctx))
2456   {
2457     GNUNET_VPN_cancel_request (vpn_ctx->vpn_request);
2458     GNUNET_free (vpn_ctx->rd_data);
2459     GNUNET_free (vpn_ctx);
2460   }
2461   if (NULL != rh->dns_request)
2462   {
2463     GNUNET_DNSSTUB_resolve_cancel (rh->dns_request);
2464     rh->dns_request = NULL;
2465   }
2466   if (NULL != rh->namecache_qe)
2467   {
2468     GNUNET_NAMECACHE_cancel (rh->namecache_qe);
2469     rh->namecache_qe = NULL;
2470   }
2471   if (NULL != rh->rev_check)
2472   {
2473     GNUNET_REVOCATION_query_cancel (rh->rev_check);
2474     rh->rev_check = NULL;
2475   }
2476   if (NULL != rh->std_resolve)
2477   {
2478     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
2479                 "Canceling standard DNS resolution\n");
2480     GNUNET_RESOLVER_request_cancel (rh->std_resolve);
2481     rh->std_resolve = NULL;
2482   }
2483   while (NULL != (dr = rh->dns_result_head))
2484   {
2485     GNUNET_CONTAINER_DLL_remove (rh->dns_result_head,
2486                                  rh->dns_result_tail,
2487                                  dr);
2488     GNUNET_free (dr);
2489   }
2490   GNUNET_free_non_null (rh->shorten_key);
2491   GNUNET_free (rh->name);
2492   GNUNET_free (rh);
2493 }
2494
2495
2496 /* ***************** Resolver initialization ********************* */
2497
2498
2499 /**
2500  * Initialize the resolver
2501  *
2502  * @param nc the namecache handle
2503  * @param dht the dht handle
2504  * @param c configuration handle
2505  * @param max_bg_queries maximum number of parallel background queries in dht
2506  */
2507 void
2508 GNS_resolver_init (struct GNUNET_NAMECACHE_Handle *nc,
2509                    struct GNUNET_DHT_Handle *dht,
2510                    const struct GNUNET_CONFIGURATION_Handle *c,
2511                    unsigned long long max_bg_queries)
2512 {
2513   char *dns_ip;
2514
2515   cfg = c;
2516   namecache_handle = nc;
2517   dht_handle = dht;
2518   dht_lookup_heap =
2519     GNUNET_CONTAINER_heap_create (GNUNET_CONTAINER_HEAP_ORDER_MIN);
2520   max_allowed_background_queries = max_bg_queries;
2521   if (GNUNET_SYSERR == (use_cache = GNUNET_CONFIGURATION_get_value_yesno (c,
2522                                              "gns",
2523                                              "USE_CACHE")))
2524     use_cache = GNUNET_YES;
2525   if (GNUNET_NO == use_cache)
2526     GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Namecache disabled\n");
2527
2528   if (GNUNET_OK !=
2529       GNUNET_CONFIGURATION_get_value_string (c,
2530                                              "gns",
2531                                              "DNS_RESOLVER",
2532                                              &dns_ip))
2533   {
2534     /* user did not specify DNS resolver, use 8.8.8.8 */
2535     dns_ip = GNUNET_strdup ("8.8.8.8");
2536   }
2537   dns_handle = GNUNET_DNSSTUB_start (dns_ip);
2538   GNUNET_free (dns_ip);
2539   vpn_handle = GNUNET_VPN_connect (cfg);
2540 }
2541
2542
2543 /**
2544  * Shutdown resolver
2545  */
2546 void
2547 GNS_resolver_done ()
2548 {
2549   struct GNS_ResolverHandle *rh;
2550   struct CacheOps *co;
2551
2552   /* abort active resolutions */
2553   while (NULL != (rh = rlh_head))
2554   {
2555     rh->proc (rh->proc_cls, 0, NULL);
2556     GNS_resolver_lookup_cancel (rh);
2557   }
2558   while (NULL != (co = co_head))
2559   {
2560     GNUNET_CONTAINER_DLL_remove (co_head,
2561                                  co_tail,
2562                                  co);
2563     GNUNET_NAMECACHE_cancel (co->namecache_qe_cache);
2564     GNUNET_free (co);
2565   }
2566   GNUNET_CONTAINER_heap_destroy (dht_lookup_heap);
2567   dht_lookup_heap = NULL;
2568   GNUNET_DNSSTUB_stop (dns_handle);
2569   dns_handle = NULL;
2570   GNUNET_VPN_disconnect (vpn_handle);
2571   vpn_handle = NULL;
2572   dht_handle = NULL;
2573   namecache_handle = NULL;
2574 }
2575
2576
2577 /* *************** common helper functions (do not really belong here) *********** */
2578
2579 /**
2580  * Checks if @a name ends in ".TLD"
2581  *
2582  * @param name the name to check
2583  * @param tld the TLD to check for
2584  * @return GNUNET_YES or GNUNET_NO
2585  */
2586 int
2587 is_tld (const char* name, const char* tld)
2588 {
2589   size_t offset = 0;
2590
2591   if (strlen (name) <= strlen (tld))
2592     return GNUNET_NO;
2593   offset = strlen (name) - strlen (tld);
2594   if (0 != strcmp (name + offset, tld))
2595     return GNUNET_NO;
2596   return GNUNET_YES;
2597 }
2598
2599
2600 /* end of gnunet-service-gns_resolver.c */