/*

 * Copyright (C) 2000-2012 Free Software Foundation, 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 <http://www.gnu.org/licenses/>

 *

 */

/* This file contains functions that manipulate a database backend for

 * resumed sessions.

 */

#include "gnutls_int.h"

#include "errors.h"

#include <db.h>

#include <session_pack.h>

#include <datum.h>

#include "ext/server_name.h"

/**

 * gnutls_db_set_retrieve_function:

 * @session: is a #gnutls_session_t type.

 * @retr_func: is the function.

 *

 * Sets the function that will be used to retrieve data from the

 * resumed sessions database.  This function must return a

 * gnutls_datum_t containing the data on success, or a gnutls_datum_t

 * containing null and 0 on failure.

 *

 * The datum's data must be allocated using the function

 * gnutls_malloc().

 *

 * The first argument to @retr_func will be null unless

 * gnutls_db_set_ptr() has been called.

 **/

void

gnutls_db_set_retrieve_function(gnutls_session_t session,

				gnutls_db_retr_func retr_func)

{

	session->internals.db_retrieve_func = retr_func;

}

/**

 * gnutls_db_set_remove_function:

 * @session: is a #gnutls_session_t type.

 * @rem_func: is the function.

 *

 * Sets the function that will be used to remove data from the

 * resumed sessions database. This function must return 0 on success.

 *

 * The first argument to @rem_func will be null unless

 * gnutls_db_set_ptr() has been called.

 **/

void

gnutls_db_set_remove_function(gnutls_session_t session,

			      gnutls_db_remove_func rem_func)

{

	session->internals.db_remove_func = rem_func;

}

/**

 * gnutls_db_set_store_function:

 * @session: is a #gnutls_session_t type.

 * @store_func: is the function

 *

 * Sets the function that will be used to store data in the resumed

 * sessions database. This function must return 0 on success.

 *

 * The first argument to @store_func will be null unless

 * gnutls_db_set_ptr() has been called.

 **/

void

gnutls_db_set_store_function(gnutls_session_t session,

			     gnutls_db_store_func store_func)

{

	session->internals.db_store_func = store_func;

}

/**

 * gnutls_db_set_ptr:

 * @session: is a #gnutls_session_t type.

 * @ptr: is the pointer

 *

 * Sets the pointer that will be provided to db store, retrieve and

 * delete functions, as the first argument.

 **/

void gnutls_db_set_ptr(gnutls_session_t session, void *ptr)

{

	session->internals.db_ptr = ptr;

}

/**

 * gnutls_db_get_ptr:

 * @session: is a #gnutls_session_t type.

 *

 * Get db function pointer.

 *

 * Returns: the pointer that will be sent to db store, retrieve and

 *   delete functions, as the first argument.

 **/

void *gnutls_db_get_ptr(gnutls_session_t session)

{

	return session->internals.db_ptr;

}

/**

 * gnutls_db_set_cache_expiration:

 * @session: is a #gnutls_session_t type.

 * @seconds: is the number of seconds.

 *

 * Set the expiration time for resumed sessions. The default is 3600

 * (one hour) at the time of this writing.

 **/

void gnutls_db_set_cache_expiration(gnutls_session_t session, int seconds)

{

	session->internals.expire_time = seconds;

}

/**

 * gnutls_db_get_default_cache_expiration:

 *

 * Returns the expiration time (in seconds) of stored sessions for resumption. 

 **/

unsigned gnutls_db_get_default_cache_expiration(void)

{

	return DEFAULT_EXPIRE_TIME;

}

/**

 * gnutls_db_check_entry:

 * @session: is a #gnutls_session_t type.

 * @session_entry: is the session data (not key)

 *

 * This function has no effect. 

 *

 * Returns: Returns %GNUTLS_E_EXPIRED, if the database entry has

 *   expired or 0 otherwise.

 **/

int

gnutls_db_check_entry(gnutls_session_t session,

		      gnutls_datum_t session_entry)

{

	return 0;

}

/**

 * gnutls_db_check_entry_time:

 * @entry: is a pointer to a #gnutls_datum_t type.

 * @t: is the time of the session handshake

 *

 * This function returns the time that this entry was active.

 * It can be used for database entry expiration.

 *

 * Returns: The time this entry was created, or zero on error.

 **/

time_t gnutls_db_check_entry_time(gnutls_datum_t * entry)

{

	uint32_t t;

	uint32_t magic;

	if (entry->size < 8)

		return gnutls_assert_val(0);

	magic = _gnutls_read_uint32(entry->data);

	if (magic != PACKED_SESSION_MAGIC)

		return gnutls_assert_val(0);

	t = _gnutls_read_uint32(&entry->data[4]);

	return t;

}

/* Checks if both db_store and db_retrieve functions have

 * been set up.

 */

static int db_func_is_ok(gnutls_session_t session)

{

	if (session->internals.db_store_func != NULL &&

	    session->internals.db_retrieve_func != NULL)

		return 0;

	else

		return GNUTLS_E_DB_ERROR;

}

/* Stores session data to the db backend.

 */

static int

store_session(gnutls_session_t session,

	      gnutls_datum_t session_id, gnutls_datum_t session_data)

{

	int ret = 0;

	if (db_func_is_ok(session) != 0) {

		return GNUTLS_E_DB_ERROR;

	}

	if (session_data.data == NULL || session_data.size == 0) {

		gnutls_assert();

		return GNUTLS_E_INVALID_SESSION;

	}

	/* if we can't read why bother writing? */

	ret = session->internals.db_store_func(session->internals.db_ptr,

					       session_id, session_data);

	return (ret == 0 ? ret : GNUTLS_E_DB_ERROR);

}

int _gnutls_server_register_current_session(gnutls_session_t session)

{

	gnutls_datum_t key;

	gnutls_datum_t content;

	int ret = 0;

	key.data = session->security_parameters.session_id;

	key.size = session->security_parameters.session_id_size;

	if (session->internals.resumable == RESUME_FALSE) {

		gnutls_assert();

		return GNUTLS_E_INVALID_SESSION;

	}

	if (session->security_parameters.session_id_size == 0) {

		gnutls_assert();

		return GNUTLS_E_INVALID_SESSION;

	}

	ret = _gnutls_session_pack(session, &content);

	if (ret < 0) {

		gnutls_assert();

		return ret;

	}

	ret = store_session(session, key, content);

	_gnutls_free_datum(&content);

	return ret;

}

int _gnutls_check_resumed_params(gnutls_session_t session)

{

	if (session->internals.resumed_security_parameters.ext_master_secret != 

	    session->security_parameters.ext_master_secret)

	    return gnutls_assert_val(GNUTLS_E_INVALID_SESSION);

	if (!_gnutls_server_name_matches_resumed(session))

	    return gnutls_assert_val(GNUTLS_E_INVALID_SESSION);

	return 0;

}

int

_gnutls_server_restore_session(gnutls_session_t session,

			       uint8_t * session_id, int session_id_size)

{

	gnutls_datum_t data;

	gnutls_datum_t key;

	int ret;

	if (session_id == NULL || session_id_size == 0) {

		gnutls_assert();

		return GNUTLS_E_INVALID_REQUEST;

	}

	if (session->internals.premaster_set != 0) {	/* hack for CISCO's DTLS-0.9 */

		if (session_id_size ==

		    session->internals.resumed_security_parameters.

		    session_id_size

		    && memcmp(session_id,

			      session->internals.

			      resumed_security_parameters.session_id,

			      session_id_size) == 0)

			return 0;

	}

	key.data = session_id;

	key.size = session_id_size;

	if (db_func_is_ok(session) != 0) {

		gnutls_assert();

		return GNUTLS_E_INVALID_SESSION;

	}

	data =

	    session->internals.db_retrieve_func(session->internals.db_ptr,

						key);

	if (data.data == NULL) {

		gnutls_assert();

		return GNUTLS_E_INVALID_SESSION;

	}

	/* expiration check is performed inside */

	ret = gnutls_session_set_data(session, data.data, data.size);

	gnutls_free(data.data);

	if (ret < 0) {

		gnutls_assert();

		return ret;

	}

	ret = _gnutls_check_resumed_params(session);

	if (ret < 0)

		return gnutls_assert_val(ret);

	return 0;

}

/**

 * gnutls_db_remove_session:

 * @session: is a #gnutls_session_t type.

 *

 * This function will remove the current session data from the

 * session database.  This will prevent future handshakes reusing

 * these session data.  This function should be called if a session

 * was terminated abnormally, and before gnutls_deinit() is called.

 *

 * Normally gnutls_deinit() will remove abnormally terminated

 * sessions.

 **/

void gnutls_db_remove_session(gnutls_session_t session)

{

	gnutls_datum_t session_id;

	int ret = 0;

	session_id.data = session->security_parameters.session_id;

	session_id.size = session->security_parameters.session_id_size;

	if (session->internals.db_remove_func == NULL) {

		gnutls_assert();

		return /* GNUTLS_E_DB_ERROR */ ;

	}

	if (session_id.data == NULL || session_id.size == 0) {

		gnutls_assert();

		return /* GNUTLS_E_INVALID_SESSION */ ;

	}

	/* if we can't read why bother writing? */

	ret = session->internals.db_remove_func(session->internals.db_ptr,

						session_id);

	if (ret != 0)

		gnutls_assert();

}