/*

 * Copyright (C) 2017 Red Hat, Inc.

 *

 * Author: Nikos Mavrogiannopoulos

 *

 * This file is part of GnuTLS.

 *

 * The GnuTLS 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_EXTV_H

#define GNUTLS_LIB_EXTV_H

#include <gnutls/gnutls.h>

#include "str.h"

/* Iterates through all TLS-type extensions in data, and

 * calls the callback function for each of them. The ctx, flags

 * and parse_type are passed verbatim to callback. */

int _gnutls_extv_parse(void *ctx,

		       gnutls_ext_raw_process_func cb,

		       const uint8_t * data, int data_size);

inline static

int _gnutls_extv_append_init(gnutls_buffer_st *buf)

{

	unsigned pos;

	int ret;

	pos = buf->length;

	ret = _gnutls_buffer_append_prefix(buf, 16, 0);

	if (ret < 0)

		return gnutls_assert_val(ret);

	return pos;

}

/* its input is the buffer and the return value of _gnutls_extv_append_init()

 * @is_hello: should be true for client and server hello messages.

 */

inline static

int _gnutls_extv_append_final(gnutls_buffer_st *buf, unsigned init, unsigned is_hello)

{

	unsigned size = buf->length - init - 2;

	if (size > UINT16_MAX) /* sent too many extensions */

		return gnutls_assert_val(GNUTLS_E_HANDSHAKE_TOO_LARGE);

	if (size > 0)

		_gnutls_write_uint16(size, &buf->data[init]);

	else if (is_hello && size == 0) {

		/* there is no point to send empty extension bytes, and

		 * they are known to break certain clients */

		buf->length -= 2;

	}

	return 0;

}

typedef int (*extv_append_func)(void *ctx, gnutls_buffer_st *buf);

int _gnutls_extv_append(gnutls_buffer_st *buf,

			uint16_t tls_id,

		        void *ctx,

		        extv_append_func cb);

#endif /* GNUTLS_LIB_EXTV_H */