/*
     This file is part of GNUnet
     (C) 2010, 2013 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 fs/plugin_block_fs.c
 * @brief blocks used for file-sharing
 * @author Christian Grothoff
 */

#include "platform.h"
#include "gnunet_block_plugin.h"
#include "gnunet_fs_service.h"
#include "block_fs.h"
#include "gnunet_signatures.h"


/**
 * Number of bits we set per entry in the bloomfilter.
 * Do not change!
 */
#define BLOOMFILTER_K 16

/**
 * Function called to validate a reply or a request.  For
 * request evaluation, simply pass "NULL" for the reply_block.
 * Note that it is assumed that the reply has already been
 * matched to the key (and signatures checked) as it would
 * be done with the "get_key" function.
 *
 * @param cls closure
 * @param type block type
 * @param query original query (hash)
 * @param bf pointer to bloom filter associated with query; possibly updated (!)
 * @param bf_mutator mutation value for bf
 * @param xquery extrended query data (can be NULL, depending on type)
 * @param xquery_size number of bytes in xquery
 * @param reply_block response to validate
 * @param reply_block_size number of bytes in reply block
 * @return characterization of result
 */
static enum GNUNET_BLOCK_EvaluationResult
block_plugin_fs_evaluate (void *cls, enum GNUNET_BLOCK_Type type,
                          const struct GNUNET_HashCode *query,
                          struct GNUNET_CONTAINER_BloomFilter **bf,
                          int32_t bf_mutator, const void *xquery,
                          size_t xquery_size, const void *reply_block,
                          size_t reply_block_size)
{
  const struct UBlock *ub;
  struct GNUNET_HashCode hc;
  struct GNUNET_HashCode chash;
  struct GNUNET_HashCode mhash;

  switch (type)
  {
  case GNUNET_BLOCK_TYPE_FS_DBLOCK:
  case GNUNET_BLOCK_TYPE_FS_IBLOCK:
    if (0 != xquery_size)
    {
      GNUNET_break_op (0);
      return GNUNET_BLOCK_EVALUATION_REQUEST_INVALID;
    }
    if (NULL == reply_block)
      return GNUNET_BLOCK_EVALUATION_REQUEST_VALID;
    return GNUNET_BLOCK_EVALUATION_OK_LAST;
  case GNUNET_BLOCK_TYPE_FS_UBLOCK:
    if (0 != xquery_size)
    {
      GNUNET_break_op (0);
      return GNUNET_BLOCK_EVALUATION_REQUEST_INVALID;
    }
    if (NULL == reply_block)
      return GNUNET_BLOCK_EVALUATION_REQUEST_VALID;

    if (reply_block_size < sizeof (struct UBlock))
    {
      GNUNET_break_op (0);
      return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
    }
    ub = reply_block;
    GNUNET_CRYPTO_hash (&ub->verification_key,
			sizeof (ub->verification_key),
			&hc);
    if (0 != memcmp (&hc,
		     query,
		     sizeof (struct GNUNET_HashCode)))
    {
      GNUNET_break_op (0);
      return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
    }
    if (reply_block_size != ntohl (ub->purpose.size) + sizeof (struct GNUNET_CRYPTO_EcdsaSignature))
    {
      GNUNET_break_op (0);
      return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
    }
    if (GNUNET_OK !=
	GNUNET_CRYPTO_ecdsa_verify (GNUNET_SIGNATURE_PURPOSE_FS_UBLOCK,
				  &ub->purpose,
				  &ub->signature,
				  &ub->verification_key))
    {
      GNUNET_break_op (0);
      return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
    }
    if (NULL != bf)
    {
      GNUNET_CRYPTO_hash (reply_block, reply_block_size, &chash);
      GNUNET_BLOCK_mingle_hash (&chash, bf_mutator, &mhash);
      if (NULL != *bf)
      {
        if (GNUNET_YES == GNUNET_CONTAINER_bloomfilter_test (*bf, &mhash))
          return GNUNET_BLOCK_EVALUATION_OK_DUPLICATE;
      }
      else
      {
        *bf = GNUNET_CONTAINER_bloomfilter_init (NULL, 8, BLOOMFILTER_K);
      }
      GNUNET_CONTAINER_bloomfilter_add (*bf, &mhash);
    }
    return GNUNET_BLOCK_EVALUATION_OK_MORE;
  default:
    return GNUNET_BLOCK_EVALUATION_TYPE_NOT_SUPPORTED;
  }
}


/**
 * Function called to obtain the key for a block.
 *
 * @param cls closure
 * @param type block type
 * @param block block to get the key for
 * @param block_size number of bytes in block
 * @param key set to the key (query) for the given block
 * @return GNUNET_OK on success, GNUNET_SYSERR if type not supported
 *         (or if extracting a key from a block of this type does not work)
 */
static int
block_plugin_fs_get_key (void *cls, enum GNUNET_BLOCK_Type type,
                         const void *block, size_t block_size,
                         struct GNUNET_HashCode *key)
{
  const struct UBlock *ub;

  switch (type)
  {
  case GNUNET_BLOCK_TYPE_FS_DBLOCK:
  case GNUNET_BLOCK_TYPE_FS_IBLOCK:
    GNUNET_CRYPTO_hash (block, block_size, key);
    return GNUNET_OK;
  case GNUNET_BLOCK_TYPE_FS_UBLOCK:
    if (block_size < sizeof (struct UBlock))
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
    ub = block;
    GNUNET_CRYPTO_hash (&ub->verification_key,
			sizeof (ub->verification_key),
			key);
    return GNUNET_OK;
  default:
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
}


/**
 * Entry point for the plugin.
 */
void *
libgnunet_plugin_block_fs_init (void *cls)
{
  static enum GNUNET_BLOCK_Type types[] =
  {
    GNUNET_BLOCK_TYPE_FS_DBLOCK,
    GNUNET_BLOCK_TYPE_FS_IBLOCK,
    GNUNET_BLOCK_TYPE_FS_UBLOCK,
    GNUNET_BLOCK_TYPE_ANY       /* end of list */
  };
  struct GNUNET_BLOCK_PluginFunctions *api;

  api = GNUNET_new (struct GNUNET_BLOCK_PluginFunctions);
  api->evaluate = &block_plugin_fs_evaluate;
  api->get_key = &block_plugin_fs_get_key;
  api->types = types;
  return api;
}


/**
 * Exit point from the plugin.
 */
void *
libgnunet_plugin_block_fs_done (void *cls)
{
  struct GNUNET_TRANSPORT_PluginFunctions *api = cls;

  GNUNET_free (api);
  return NULL;
}

/* end of plugin_block_fs.c */