/*
 * Copyright (C) 2009-2012 Free Software Foundation, Inc.
 *
 * Author: Jonathan Bastien-Filiatrault
 *
 * This file is part of GNUTLS.
 *
 * The GNUTLS library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

#ifndef GNUTLS_MBUFFERS_H
#define GNUTLS_MBUFFERS_H

#include <gnutls_int.h>
#include <gnutls_errors.h>

void _mbuffer_head_init (mbuffer_head_st * buf);
void _mbuffer_head_clear (mbuffer_head_st * buf);
void _mbuffer_enqueue (mbuffer_head_st * buf, mbuffer_st * bufel);
mbuffer_st* _mbuffer_dequeue (mbuffer_head_st * buf, mbuffer_st * bufel);
int _mbuffer_head_remove_bytes (mbuffer_head_st * buf, size_t bytes);
mbuffer_st *_mbuffer_alloc (size_t payload_size, size_t maximum_size);

mbuffer_st *_mbuffer_head_get_first (mbuffer_head_st * buf, gnutls_datum_t * msg);
mbuffer_st *_mbuffer_head_get_next (mbuffer_st * cur, gnutls_datum_t * msg);

mbuffer_st *
_mbuffer_head_pop_first (mbuffer_head_st * buf);

/* This is dangerous since it will replace bufel with a new
 * one.
 */
int _mbuffer_append_data (mbuffer_st * bufel, void *newdata,
                          size_t newdata_size);
int _mbuffer_linearize (mbuffer_head_st * buf);


/* For "user" use. One can have buffer data and header.
 */

inline static void
_mbuffer_set_udata (mbuffer_st * bufel, void *data, size_t data_size)
{
  memcpy (bufel->msg.data + bufel->mark + bufel->user_mark, data, data_size);
  bufel->msg.size = data_size + bufel->user_mark + bufel->mark;
}

inline static void *
_mbuffer_get_uhead_ptr (mbuffer_st * bufel)
{
  return bufel->msg.data + bufel->mark;
}

inline static void *
_mbuffer_get_udata_ptr (mbuffer_st * bufel)
{
  return bufel->msg.data + bufel->user_mark + bufel->mark;
}

inline static void
_mbuffer_set_udata_size (mbuffer_st * bufel, size_t size)
{
  bufel->msg.size = size + bufel->user_mark + bufel->mark;
}

inline static size_t
_mbuffer_get_udata_size (mbuffer_st * bufel)
{
  return bufel->msg.size - bufel->user_mark - bufel->mark;
}

/* discards size bytes from the begging of the buffer */
inline static void
_mbuffer_consume (mbuffer_head_st* buf, mbuffer_st * bufel, size_t size)
{
  bufel->user_mark = 0;
  if (bufel->mark+size < bufel->msg.size)
    bufel->mark += size;
  else
    bufel->mark = bufel->msg.size;

  buf->byte_length -= size;
}

inline static size_t
_mbuffer_get_uhead_size (mbuffer_st * bufel)
{
  return bufel->user_mark;
}

inline static void
_mbuffer_set_uhead_size (mbuffer_st * bufel, size_t size)
{
  bufel->user_mark = size;
}



inline static mbuffer_st *
_gnutls_handshake_alloc (gnutls_session_t session, size_t size, size_t maximum)
{
  mbuffer_st *ret = _mbuffer_alloc (HANDSHAKE_HEADER_SIZE(session) + size,
                                    HANDSHAKE_HEADER_SIZE(session) + maximum);

  if (!ret)
    return NULL;

  _mbuffer_set_uhead_size (ret, HANDSHAKE_HEADER_SIZE(session));

  return ret;
}

/* Free a segment, if the pointer is not NULL
 *
 * We take a ** to detect and fix double free bugs (the dangling
 * pointer case). It also makes sure the pointer has a known value
 * after freeing.
 */
inline static void
_mbuffer_xfree (mbuffer_st ** bufel)
{
  if (*bufel)
    gnutls_free (*bufel);

  *bufel = NULL;
}

#endif