/*

 * 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 <https://www.gnu.org/licenses/>

 *

 */

#ifndef GNUTLS_LIB_MBUFFERS_H

#define GNUTLS_LIB_MBUFFERS_H

#include "gnutls_int.h"

#include "errors.h"

#include <assert.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 maximum_size);

int _mbuffer_linearize(mbuffer_head_st * buf);

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);

void _mbuffer_head_push_first(mbuffer_head_st * buf, mbuffer_st * bufel);

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);

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

 */

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->uhead_mark + bufel->mark;

}

inline static void _mbuffer_set_udata_size(mbuffer_st * bufel, size_t size)

{

	bufel->msg.size = size + bufel->uhead_mark + bufel->mark;

}

inline static void

_mbuffer_set_udata(mbuffer_st * bufel, void *data, size_t data_size)

{

	memcpy(_mbuffer_get_udata_ptr(bufel), data,

	       data_size);

	_mbuffer_set_udata_size(bufel, data_size);

}

inline static size_t _mbuffer_get_udata_size(mbuffer_st * bufel)

{

	return bufel->msg.size - bufel->uhead_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->uhead_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->uhead_mark;

}

inline static void _mbuffer_set_uhead_size(mbuffer_st * bufel, size_t size)

{

	bufel->uhead_mark = size;

}

inline static void _mbuffer_init(mbuffer_st *bufel, size_t max)

{

	memset(bufel, 0, sizeof(*bufel));

	bufel->maximum_size = max;

	/* payload points after the mbuffer_st structure */

	bufel->msg.data = (uint8_t *) bufel + sizeof(mbuffer_st);

}

/* Helper functions to utilize a gnutls_buffer_st in order

 * to generate a gnutls_mbuffer_st, without multiple allocations.

 */

inline static int _gnutls_buffer_init_mbuffer(gnutls_buffer_st * buf, size_t header_size)

{

	int ret;

	mbuffer_st *bufel;

	_gnutls_buffer_init(buf);

	ret = _gnutls_buffer_resize(buf, sizeof(mbuffer_st)+header_size);

	if (ret < 0)

		return gnutls_assert_val(ret);

	/* we store the uhead size on the uninitialized bufel, only to read

	 * it back on _gnutls_buffer_to_mbuffer(). */

	bufel = (void*)buf->data;

	_mbuffer_set_uhead_size(bufel, header_size);

	buf->length = sizeof(mbuffer_st)+header_size;

	return 0;

}

#define _gnutls_buffer_init_handshake_mbuffer(b) _gnutls_buffer_init_mbuffer(b, HANDSHAKE_HEADER_SIZE(session))

/* Cannot fail */

inline static mbuffer_st *_gnutls_buffer_to_mbuffer(gnutls_buffer_st * buf)

{

	mbuffer_st *bufel;

	unsigned header_size;

	bufel = (void*)buf->data;

	header_size = _mbuffer_get_uhead_size(bufel);

	assert(buf->length >= sizeof(mbuffer_st)+header_size);

	_mbuffer_init(bufel, buf->length - sizeof(mbuffer_st));

	_mbuffer_set_udata_size(bufel, buf->length - sizeof(mbuffer_st));

	_mbuffer_set_uhead_size(bufel, header_size);

	_gnutls_buffer_init(buf); /* avoid double frees */

	return bufel;

}

inline static mbuffer_st *_gnutls_handshake_alloc(gnutls_session_t session,

						  size_t maximum)

{

	mbuffer_st *bufel =

	    _mbuffer_alloc(HANDSHAKE_HEADER_SIZE(session) + maximum);

	if (!bufel)

		return NULL;

	_mbuffer_set_uhead_size(bufel, HANDSHAKE_HEADER_SIZE(session));

	_mbuffer_set_udata_size(bufel, maximum);

	return bufel;

}

/* 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;

}

#ifdef ENABLE_ALIGN16

mbuffer_st *_mbuffer_alloc_align16(size_t maximum_size, unsigned align_pos);

int _mbuffer_linearize_align16(mbuffer_head_st * buf, unsigned align_pos);

#else

# define _mbuffer_alloc_align16(x,y) _mbuffer_alloc(x)

# define _mbuffer_linearize_align16(x,y) _mbuffer_linearize(x)

#endif

#endif /* GNUTLS_LIB_MBUFFERS_H */