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/*
     This file is part of GNUnet.
     (C) 2009, 2010, 2011 Christian Grothoff (and other contributing authors)

     GNUnet is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published
     by the Free Software Foundation; either version 3, or (at your
     option) any later version.

     GNUnet is distributed in the hope that it will be useful, but
     WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file gns/gnunet-service-gns.c
 * @brief GNUnet GNS service
 * @author Martin Schanzenbach
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_transport_service.h"
#include "gnunet_dns_service.h"
#include "gnunet_dnsparser_lib.h"
#include "gnunet_namestore_service.h"
#include "gnunet_gns_service.h"
#include "gns.h"


/* TODO into gnunet_protocols */
#define GNUNET_MESSAGE_TYPE_GNS_CLIENT_LOOKUP 23
#define GNUNET_MESSAGE_TYPE_GNS_CLIENT_RESULT 24

/**
 * A result list for namestore queries
 */
struct GNUNET_GNS_PendingQuery
{
  /* the answer packet */
  struct GNUNET_DNSPARSER_Packet *answer;

  /* records to put into answer packet */
  struct GNUNET_CONTAINER_SList *records;

  int num_records;
  int num_authority_records; //FIXME are all of our replies auth?
  
  /* the dns request id */
  int id; // FIXME can handle->request_id also be used here?

  /* the request handle to reply to */
  struct GNUNET_DNS_RequestHandle *request_handle;
};


/**
 * Our handle to the DNS handler library
 */
struct GNUNET_DNS_Handle *dns_handle;

/**
 * Our handle to the namestore service
 */
struct GNUNET_NAMESTORE_Handle *namestore_handle;

/**
 * The configuration the GNS service is running with
 */
const struct GNUNET_CONFIGURATION_Handle *GNS_cfg;

/**
 * Our notification context.
 */
static struct GNUNET_SERVER_NotificationContext *nc;

/**
 * Our zone hash
 */
const GNUNET_HashCode *my_zone;

/**
 * Task run during shutdown.
 *
 * @param cls unused
 * @param tc unused
 */
static void
shutdown_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  GNUNET_DNS_disconnect(dns_handle);
}

static void
process_ns_result(void* cls, const GNUNET_HashCode *zone,
                  const char *name, uint32_t record_type,
                  struct GNUNET_TIME_Absolute expiration,
                  enum GNUNET_NAMESTORE_RecordFlags flags,
                  const struct GNUNET_NAMESTORE_SignatureLocation *sig_loc,
                  size_t size, const void *data)
{
  struct GNUNET_GNS_PendingQuery *answer;
  struct GNUNET_DNSPARSER_Record *record;
  struct GNUNET_DNSPARSER_Packet *packet;
  struct GNUNET_DNSPARSER_Flags dnsflags;
  char *reply_buffer;
  
  answer = (struct GNUNET_GNS_PendingQuery *) cls;


  if (NULL == data)
  {
    /**
     * Last result received (or none)
     * FIXME extract to func
     */
    reply_buffer = GNUNET_malloc(6000); //FIXME magic number
    packet = GNUNET_malloc(sizeof(struct GNUNET_DNSPARSER_Packet));
    packet->answers =
      GNUNET_malloc(sizeof(struct GNUNET_DNSPARSER_Record) * answer->num_records);
    /* FIXME how to handle auth, additional etc */
    packet->num_answers = answer->num_records;
    packet->num_authority_records = answer->num_authority_records;
    
    dnsflags.authoritative_answer = 1;
    dnsflags.return_code = GNUNET_DNSPARSER_RETURN_CODE_YXDOMAIN; //not sure
    dnsflags.query_or_response = 1;
    packet->flags = dnsflags;

    packet->id = answer->id;
    size_t bufsize = 6000;
    int ret = GNUNET_DNSPARSER_pack (packet,
                           600, /* FIXME max udp payload */
                           &reply_buffer,
                           &bufsize); // FIXME magic number bufsize
    if (ret == GNUNET_OK)
    {
      GNUNET_DNS_request_answer(answer->request_handle,
                                6000, //FIXME what length here
                                reply_buffer);
    }
    else
    {
      //FIXME log
    }
  }
  else
  {
    /**
     * New result
     */
    record = GNUNET_malloc(sizeof(struct GNUNET_DNSPARSER_Record));
    record->name = (char*)name;
    /* FIXME for gns records this requires the dnsparser to be modified!*/
    //record->data = data; FIXME!
    record->expiration_time = expiration;
    record->type = record_type;
    record->class = GNUNET_DNSPARSER_CLASS_INTERNET; /* srsly? */
    
    if (flags == GNUNET_NAMESTORE_RF_AUTHORITY)
    {
      answer->num_authority_records++;
    }
    
    answer->num_records++;
    
    //FIXME watch for leaks
    GNUNET_CONTAINER_slist_add (answer->records,
                                GNUNET_CONTAINER_SLIST_DISPOSITION_DYNAMIC,
                                &record, sizeof(struct GNUNET_DNSPARSER_Record*));
  }
}


/**
 * The DNS request handler
 * Is this supposed to happen here in the service (config option)
 * or in an app that interfaces with the GNS API?
 *
 * @param cls closure
 * @param rh request handle to user for reply
 * @param request_length number of bytes in request
 * @param request udp payload of the DNS request
 */
void
handle_dns_request(void *cls,
                   struct GNUNET_DNS_RequestHandle *rh,
                   size_t request_length,
                   const char *request)
{
  /**
   * parse request for tld
   */
  struct GNUNET_DNSPARSER_Packet *p;
  struct GNUNET_GNS_PendingQuery *answer;
  int namelen;
  int i;
  char *tail;
  
  p = GNUNET_DNSPARSER_parse (request, request_length);
  if (NULL == p)
  {
    fprintf (stderr, "Received malformed DNS packet, leaving it untouched\n");
    GNUNET_DNS_request_forward (rh);
    return;
  }
  /**
   * FIXME factor out
   * Check tld and decide if we or
   * legacy dns is responsible
   */
  for (i=0;i<p->num_queries;i++)
  {
    namelen = strlen(p->queries[i].name);
    
    if (namelen < 7) /* this can't be .gnunet */
      continue;
    /**
     * FIXME off by 1?
     * Move our tld/root to config file
     * Generate fake DNS reply that replaces .gnunet with .org for testing?
     */
    tail = p->queries[i].name+(namelen-7);
    if (0 == strcmp(tail, ".gnunet"))
    {
      /**
       * Do db lookup here. Make dht lookup if necessary 
       * FIXME for now only local lookups for our zone!
       */
      answer = GNUNET_malloc(sizeof (struct GNUNET_GNS_PendingQuery));
      answer->records = GNUNET_CONTAINER_slist_create ();
      answer->id = p->id;

      GNUNET_NAMESTORE_lookup_name(namestore_handle,
                                   my_zone,
                                   p->queries[i].name,
                                   p->queries[i].type,
                                   &process_ns_result,
                                   answer);
      //GNUNET_DNS_request_answer(rh, 0 /*length*/, NULL/*reply*/);
    }
    else
    {
      GNUNET_DNS_request_forward (rh);
    }
  }
}

/*TODO*/
static void
handle_client_record_lookup(void *cls,
                            struct GNUNET_SERVER_Client *client,
                            const struct GNUNET_MessageHeader *message)
{
}

/**
 * Process GNS requests.
 *
 * @param cls closure
 * @param server the initialized server
 * @param c configuration to use
 */
static void
run (void *cls, struct GNUNET_SERVER_Handle *server,
     const struct GNUNET_CONFIGURATION_Handle *c)
{
  /* The IPC message types */
  static const struct GNUNET_SERVER_MessageHandler handlers[] = {
    /* callback, cls, type, size */
    {&handle_client_record_lookup, NULL, GNUNET_MESSAGE_TYPE_GNS_CLIENT_LOOKUP,
      0},
    {NULL, NULL, 0, 0}
  };
  
  nc = GNUNET_SERVER_notification_context_create (server, 1);

  /* FIXME - do some config parsing 
   *       - Maybe only hijack dns if option is set (HIJACK_DNS=1)
   */

  GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL, &shutdown_task,
                                NULL);
  /**
   * Do gnunet dns init here
   */
  dns_handle = GNUNET_DNS_connect(c,
                                  GNUNET_DNS_FLAG_PRE_RESOLUTION,
                                  &handle_dns_request, /* rh */
                                  NULL); /* Closure */

  /**
   * handle to our local namestore
   */
  namestore_handle = GNUNET_NAMESTORE_connect(c);

  GNUNET_SERVER_add_handlers (server, handlers);
  /**
   * Esp the lookup would require to keep track of the clients' context
   * See dht.
   * GNUNET_SERVER_disconnect_notify (server, &client_disconnect, NULL);
   **/
}


/**
 * The main function for the GNS service.
 *
 * @param argc number of arguments from the command line
 * @param argv command line arguments
 * @return 0 ok, 1 on error
 */
int
main (int argc, char *const *argv)
{
  int ret;

  ret =
      (GNUNET_OK ==
       GNUNET_SERVICE_run (argc, argv, "gns", GNUNET_SERVICE_OPTION_NONE, &run,
                           NULL)) ? 0 : 1;
  return ret;
}

/* end of gnunet-service-gns.c */