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

#include "platform.h"
#include "plugin_block.h"
#include "gnunet_signatures.h"

#define DEBUG_FS_BLOCK GNUNET_NO

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

/**
 * Mingle hash with the mingle_number to produce different bits.
 */
static void
mingle_hash (const GNUNET_HashCode * in,
	     int32_t mingle_number, 
	     GNUNET_HashCode * hc)
{
  GNUNET_HashCode m;

  GNUNET_CRYPTO_hash (&mingle_number, 
		      sizeof (int32_t), 
		      &m);
  GNUNET_CRYPTO_hash_xor (&m, in, hc);
}


/**
 * 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 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 SBlock *sb;
  GNUNET_HashCode chash;
  GNUNET_HashCode mhash;
  const GNUNET_HashCode *nsid;
  GNUNET_HashCode sh;

  switch (type)
    {
    case GNUNET_BLOCK_TYPE_DBLOCK:
    case GNUNET_BLOCK_TYPE_IBLOCK:
      if (xquery_size != 0) 
	{
	  GNUNET_break_op (0);
	  return GNUNET_BLOCK_EVALUATION_REQUEST_INVALID;
	}
      return GNUNET_BLOCK_EVALUATION_OK_LAST;
    case GNUNET_BLOCK_TYPE_KBLOCK:
    case GNUNET_BLOCK_TYPE_NBLOCK:
      if (xquery_size != 0) 
	{
	  GNUNET_break_op (0);
	  return GNUNET_BLOCK_EVALUATION_REQUEST_INVALID;
	}
      if (reply_block == NULL)
	return GNUNET_BLOCK_EVALUATION_REQUEST_VALID;
      GNUNET_CRYPTO_hash (reply_block,
			  reply_block_size,
			  &chash);
      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;
    case GNUNET_BLOCK_TYPE_SBLOCK:
      if (xquery_size != sizeof (GNUNET_HashCode)) 
	{
	  GNUNET_break_op (0);
	  return GNUNET_BLOCK_EVALUATION_REQUEST_INVALID;
	}
      if (reply_block == NULL)
	return GNUNET_BLOCK_EVALUATION_REQUEST_VALID;
      nsid = xquery;
      if (reply_block_size < sizeof (struct NBlock))
	return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
      sb = reply_block;
      GNUNET_CRYPTO_hash (&sb->subspace,
			  sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded),
			  &sh);
      if (0 != memcmp (nsid,
		       &sh,
		       sizeof (GNUNET_HashCode)))
	{
	  GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
		      _("Reply mismatched in terms of namespace.  Discarded.\n"));
	  return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
	}
      GNUNET_CRYPTO_hash (reply_block,
			  reply_block_size,
			  &chash);
      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,
			 GNUNET_HashCode *key)
{
  const struct KBlock *kb;
  const struct SBlock *sb;
  const struct NBlock *nb;

  switch (type)
    {
    case GNUNET_BLOCK_TYPE_DBLOCK:
    case GNUNET_BLOCK_TYPE_IBLOCK:
      GNUNET_CRYPTO_hash (block, block_size, key);
      return GNUNET_OK;
    case GNUNET_BLOCK_TYPE_KBLOCK:
      if (block_size < sizeof (struct KBlock))
	{
	  GNUNET_break_op (0);
	  return GNUNET_SYSERR;
	}
      kb = block;
      if (block_size - sizeof (struct KBlock) !=
	  ntohl (kb->purpose.size) 
	  - sizeof (struct GNUNET_CRYPTO_RsaSignaturePurpose) 
	  - sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded) ) 
	{
	  GNUNET_break_op (0);
	  return GNUNET_SYSERR;
	}
      if (GNUNET_OK !=
	  GNUNET_CRYPTO_rsa_verify (GNUNET_SIGNATURE_PURPOSE_FS_KBLOCK,
				    &kb->purpose,
				    &kb->signature,
				    &kb->keyspace)) 
	{
	  GNUNET_break_op (0);
	  return GNUNET_SYSERR;
	}
      if (key != NULL)
	GNUNET_CRYPTO_hash (&kb->keyspace,
			    sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded),
			    key);
      return GNUNET_OK;
    case GNUNET_BLOCK_TYPE_SBLOCK:
      if (block_size < sizeof (struct SBlock))
	{
	  GNUNET_break_op (0);
	  return GNUNET_SYSERR;
	}
      sb = block;
      if (block_size !=
	  ntohl (sb->purpose.size) + sizeof (struct GNUNET_CRYPTO_RsaSignature))
	{
	  GNUNET_break_op (0);
	  return GNUNET_SYSERR;
	}
      if (GNUNET_OK !=
	  GNUNET_CRYPTO_rsa_verify (GNUNET_SIGNATURE_PURPOSE_FS_SBLOCK,
				    &sb->purpose,
				    &sb->signature,
				    &sb->subspace)) 
	{
	  GNUNET_break_op (0);
	  return GNUNET_SYSERR;
	}
      if (key != NULL)
	*key = sb->identifier;
      return GNUNET_OK;
    case GNUNET_BLOCK_TYPE_NBLOCK:
      if (block_size < sizeof (struct NBlock))
	{
	  GNUNET_break_op (0);
	  return GNUNET_SYSERR;
	}
      nb = block;
      if (block_size - sizeof (struct NBlock) !=
	  ntohl (nb->ns_purpose.size) 
	  - sizeof (struct GNUNET_CRYPTO_RsaSignaturePurpose) 
	  - sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded) ) 
	{
	  GNUNET_break_op (0);
	  return GNUNET_SYSERR;
	}
      if (block_size !=
	  ntohl (nb->ksk_purpose.size) + sizeof (struct GNUNET_CRYPTO_RsaSignature))
	{
	  GNUNET_break_op (0);
	  return GNUNET_SYSERR;
	}
      if (GNUNET_OK !=
	  GNUNET_CRYPTO_rsa_verify (GNUNET_SIGNATURE_PURPOSE_FS_NBLOCK_KSIG,
				    &nb->ksk_purpose,
				    &nb->ksk_signature,
				    &nb->keyspace)) 
	{
	  GNUNET_break_op (0);
	  return GNUNET_SYSERR;
	}
      if (GNUNET_OK !=
	  GNUNET_CRYPTO_rsa_verify (GNUNET_SIGNATURE_PURPOSE_FS_NBLOCK,
				    &nb->ns_purpose,
				    &nb->ns_signature,
				    &nb->subspace)) 
	{
	  GNUNET_break_op (0);
	  return GNUNET_SYSERR;
	}
      /* FIXME: we used to xor ID with NSID,
	 why not here? */
      if (key != NULL)
	GNUNET_CRYPTO_hash (&nb->keyspace,
			    sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded),
			    key);
      return GNUNET_OK;
    default:
      return GNUNET_SYSERR;
    }
}
				  

/**
 * Entry point for the plugin.
 */
void *
gnunet_plugin_block_fs_init (void *cls)
{
  static enum GNUNET_BLOCK_Type types[] = 
    {
      GNUNET_BLOCK_TYPE_DBLOCK,
      GNUNET_BLOCK_TYPE_IBLOCK,
      GNUNET_BLOCK_TYPE_KBLOCK,
      GNUNET_BLOCK_TYPE_SBLOCK,
      GNUNET_BLOCK_TYPE_NBLOCK,
      GNUNET_BLOCK_TYPE_ANY /* end of list */
    };
  struct GNUNET_BLOCK_PluginFunctions *api;

  api = GNUNET_malloc (sizeof (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 *
gnunet_plugin_block_fs_done (void *cls)
{
  struct GNUNET_TRANSPORT_PluginFunctions *api = cls;

  GNUNET_free (api);
  return NULL;
}

/* end of plugin_block_fs.c */