/*

 * Copyright (C) 2000-2012 Free Software Foundation, Inc.

 * Copyright (C) 2015-2018 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_HELLO_EXT_H

#define GNUTLS_LIB_HELLO_EXT_H

#include "gnutls_int.h"

#include <gnutls/gnutls.h>

#include "str.h"

/* Functions for hello extension parsing.

 */

int _gnutls_parse_hello_extensions(gnutls_session_t session,

				   gnutls_ext_flags_t msg,

				   gnutls_ext_parse_type_t parse_type,

				   const uint8_t * data, int data_size);

int _gnutls_gen_hello_extensions(gnutls_session_t session,

				 gnutls_buffer_st * extdata,

				 gnutls_ext_flags_t msg,

				 gnutls_ext_parse_type_t);

int _gnutls_hello_ext_init(void);

void _gnutls_hello_ext_deinit(void);

void _gnutls_hello_ext_priv_deinit(gnutls_session_t session);

/* functions to be used by extensions internally

 */

void _gnutls_hello_ext_unset_priv(gnutls_session_t session,

				    extensions_t ext);

void _gnutls_hello_ext_set_priv(gnutls_session_t session, extensions_t ext,

				  gnutls_ext_priv_data_t);

int _gnutls_hello_ext_get_priv(gnutls_session_t session, extensions_t ext,

				 gnutls_ext_priv_data_t *);

int _gnutls_hello_ext_get_resumed_priv(gnutls_session_t session,

					 extensions_t ext,

					 gnutls_ext_priv_data_t * data);

#define GNUTLS_EXT_FLAG_MSG_MASK (GNUTLS_EXT_FLAG_CLIENT_HELLO | GNUTLS_EXT_FLAG_TLS12_SERVER_HELLO| \

		 GNUTLS_EXT_FLAG_TLS13_SERVER_HELLO | GNUTLS_EXT_FLAG_EE | GNUTLS_EXT_FLAG_HRR)

/* these flags can only be set in the extensions, but cannot be requested;

 * they are handled internally by the hello parsing/generating functions. */

#define GNUTLS_EXT_FLAG_SET_ONLY_FLAGS_MASK ~(GNUTLS_EXT_FLAG_DTLS | GNUTLS_EXT_FLAG_TLS)

/* obtain the message this extension was received at */

inline static gnutls_ext_flags_t _gnutls_ext_get_msg(gnutls_session_t session)

{

	return session->internals.ext_msg & GNUTLS_EXT_FLAG_MSG_MASK;

}

inline static void _gnutls_ext_set_msg(gnutls_session_t session, gnutls_ext_flags_t msg)

{

	session->internals.ext_msg = msg;

}

inline static void _gnutls_ext_set_extensions_offset(gnutls_session_t session,

		int offset)

{

	session->internals.extensions_offset = offset;

}

inline static int _gnutls_ext_get_extensions_offset(gnutls_session_t session)

{

	return session->internals.extensions_offset;

}

int _gnutls_ext_set_full_client_hello(gnutls_session_t session,

				      handshake_buffer_st *recv_buf);

unsigned _gnutls_ext_get_full_client_hello(gnutls_session_t session,

					   gnutls_datum_t *datum);

/* for session packing */

int _gnutls_hello_ext_pack(gnutls_session_t session, gnutls_buffer_st * packed);

int _gnutls_hello_ext_unpack(gnutls_session_t session,

		       gnutls_buffer_st * packed);

inline static const char *ext_msg_validity_to_str(gnutls_ext_flags_t msg)

{

	msg &= GNUTLS_EXT_FLAG_MSG_MASK;

	switch(msg) {

		case GNUTLS_EXT_FLAG_CLIENT_HELLO:

			return "client hello";

		case GNUTLS_EXT_FLAG_TLS12_SERVER_HELLO:

			return "TLS 1.2 server hello";

		case GNUTLS_EXT_FLAG_TLS13_SERVER_HELLO:

			return "TLS 1.3 server hello";

		case GNUTLS_EXT_FLAG_EE:

			return "encrypted extensions";

		case GNUTLS_EXT_FLAG_HRR:

			return "hello retry request";

		default:

			return "(unknown)";

	}

}

typedef struct hello_ext_entry_st {

	const char *name; /* const overridden when free_struct is set */

	unsigned free_struct;

	uint16_t tls_id;

	unsigned gid; /* gnutls internal ID */

	gnutls_ext_parse_type_t client_parse_point;

	gnutls_ext_parse_type_t server_parse_point;

	unsigned validity; /* multiple items of gnutls_ext_flags_t */

	/* this function must return 0 when Not Applicable

	 * size of extension data if ok

	 * < 0 on other error.

	 */

	gnutls_ext_recv_func recv_func;

	/* this function must return 0 when Not Applicable

	 * size of extension data if ok

	 * GNUTLS_E_INT_RET_0 if extension data size is zero

	 * < 0 on other error.

	 */

	gnutls_ext_send_func send_func;

	gnutls_ext_deinit_data_func deinit_func;	/* this will be called to deinitialize

							 * internal data

							 */

	gnutls_ext_pack_func pack_func;	/* packs internal data to machine independent format */

	gnutls_ext_unpack_func unpack_func;	/* unpacks internal data */

	/* non-zero if that extension cannot be overridden by the applications.

	 * That should be set to extensions which allocate data early, e.g., on

	 * gnutls_init(), or modify the TLS protocol in a way that the application

	 * cannot control. */

	unsigned cannot_be_overriden;

} hello_ext_entry_st;

/* Checks if the extension @id provided has been requested

 * by us (in client side).In server side it checks whether this

 * extension was advertized by the client.

 *

 * It returns non-zero for true, otherwise zero.

 */

inline static unsigned

_gnutls_hello_ext_is_present(gnutls_session_t session, extensions_t id)

{

	if (session->internals.used_exts & ((ext_track_t)1 << id))

		return 1;

	return 0;

}

/* Adds the extension we want to send in the extensions list.

 * This list is used in client side to check whether the (later) received

 * extensions are the ones we requested.

 *

 * In server side, this list is used to ensure we don't send

 * extensions that we didn't receive a corresponding value.

 *

 * Returns zero if failed, non-zero on success.

 */

inline static

unsigned _gnutls_hello_ext_save(gnutls_session_t session,

				extensions_t id,

				unsigned check_dup)

{

	if (check_dup && _gnutls_hello_ext_is_present(session, id)) {

			return 0;

	}

	session->internals.used_exts |= ((ext_track_t)1 << id);

	return 1;

}

inline static

void _gnutls_hello_ext_save_sr(gnutls_session_t session)

{

	_gnutls_hello_ext_save(session, GNUTLS_EXTENSION_SAFE_RENEGOTIATION, 1);

}

#endif /* GNUTLS_LIB_HELLO_EXT_H */