/*
 * Copyright (C) 2000,2002,2003 Nikos Mavroyanopoulos
 *
 * 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 library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
 *
 */

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

#include "gnutls_int.h"
#include "gnutls_errors.h"
#include "gnutls_session.h"
#include <gnutls_db.h>
#include "debug.h"
#include <gnutls_session_pack.h>

/**
  * gnutls_db_set_retrieve_function - Sets the function that will be used to get data
  * @session: is a &gnutls_session structure.
  * @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 containing the
  * data on success, or a gnutls_datum containing null and 0 on failure.
  *
  * The datum's data must be allocated using the function
  * gnutls_malloc().
  *
  * The first argument to store_function() will be null unless gnutls_db_set_ptr() 
  * has been called.
  *
  **/
void gnutls_db_set_retrieve_function( gnutls_session session, gnutls_db_retr_func retr_func) {
	session->internals.db_retrieve_func = retr_func;
}

/**
  * gnutls_db_set_remove_function - Sets the function that will be used to remove data
  * @session: is a &gnutls_session structure.
  * @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_function() will be null unless gnutls_db_set_ptr() 
  * has been called.
  *
  **/
void gnutls_db_set_remove_function( gnutls_session session, gnutls_db_remove_func rem_func) {
	session->internals.db_remove_func = rem_func;
}

/**
  * gnutls_db_set_store_function - Sets the function that will be used to put data
  * @session: is a &gnutls_session structure.
  * @store_func: is the function
  *
  * Sets the function that will be used to store data from the resumed
  * sessions database. This function must remove 0 on success. 
  *
  * The first argument to store_function() will be null unless gnutls_db_set_ptr() 
  * has been called.
  *
  **/
void gnutls_db_set_store_function( gnutls_session session, gnutls_db_store_func store_func) {
	session->internals.db_store_func = store_func;
}

/**
  * gnutls_db_set_ptr - Sets a pointer to be sent to db functions
  * @session: is a &gnutls_session structure.
  * @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 session, void* ptr) {
	session->internals.db_ptr = ptr;
}

/**
  * gnutls_db_get_ptr - Returns the pointer which is sent to db functions
  * @session: is a &gnutls_session structure.
  *
  * 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 session) {
	return session->internals.db_ptr;
}

/**
  * gnutls_db_set_cache_expiration - Sets the expiration time for resumed sessions.
  * @session: is a &gnutls_session structure.
  * @seconds: is the number of seconds.
  *
  * Sets the expiration time for resumed sessions. The default is 3600 (one hour)
  * at the time writing this.
  **/
void gnutls_db_set_cache_expiration( gnutls_session session, int seconds) {
	session->internals.expire_time = seconds;
}

/**
  * gnutls_db_check_entry - checks if the given db entry has expired
  * @session: is a &gnutls_session structure.
  * @session_entry: is the session data (not key)
  *
  * This function returns GNUTLS_E_EXPIRED, if the database entry
  * has expired or 0 otherwise. This function is to be used when
  * you want to clear unnesessary session which occupy space in your
  * backend.
  *
  **/
int gnutls_db_check_entry( gnutls_session session, gnutls_datum session_entry) {
time_t timestamp;

	timestamp = time(0);

	if (session_entry.data != NULL)
		if ( timestamp - ((SecurityParameters*)(session_entry.data))->timestamp <= session->internals.expire_time || ((SecurityParameters*)(session_entry.data))->timestamp > timestamp|| ((SecurityParameters*)(session_entry.data))->timestamp == 0)
			return GNUTLS_E_EXPIRED;
	
	return 0;
}

/* The format of storing data is:
 * (forget it). Check gnutls_session_pack.c
 */
int _gnutls_server_register_current_session( gnutls_session session)
{
gnutls_datum key = { session->security_parameters.session_id, session->security_parameters.session_id_size };
gnutls_datum content;
int ret = 0;

	if (session->internals.resumable==RESUME_FALSE) {
		gnutls_assert();
		return GNUTLS_E_INVALID_SESSION;
	}
	
	if (session->security_parameters.session_id==NULL || session->security_parameters.session_id_size==0) {
		gnutls_assert();
		return GNUTLS_E_INVALID_SESSION;
	}
	
/* allocate space for data */
	ret = _gnutls_session_size( session);
	if (ret < 0) {
		gnutls_assert();
		return ret;
	}
	content.size = ret;

	content.data = gnutls_malloc( content.size);
	if (content.data==NULL) {
		gnutls_assert();
		return GNUTLS_E_MEMORY_ERROR;
	}
	
/* copy data */
	ret = _gnutls_session_pack( session, &content);
	if (ret < 0) {
		gnutls_free( content.data);
		gnutls_assert();
		return ret;
	}

	ret = _gnutls_store_session( session, key, content);

	gnutls_free( content.data);

	return ret;
}

/* Checks if both db_store and db_retrieve functions have
 * been set up.
 */
static int _gnutls_db_func_is_ok( gnutls_session session) {
	if (session->internals.db_store_func!=NULL &&
		session->internals.db_retrieve_func!=NULL &&
		session->internals.db_remove_func!=NULL) return 0;
	else return GNUTLS_E_DB_ERROR;
}


int _gnutls_server_restore_session( gnutls_session session, uint8* session_id, int session_id_size)
{
gnutls_datum data;
gnutls_datum key = { session_id, session_id_size };
int ret;

	if (_gnutls_db_func_is_ok(session)!=0) {
		gnutls_assert();
		return GNUTLS_E_INVALID_SESSION;
	}

	data = _gnutls_retrieve_session( session, 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);
	if (ret < 0) {
		gnutls_assert();
		return ret;
	}

	gnutls_free(data.data);

	return 0;
}

int _gnutls_db_remove_session( gnutls_session session, uint8* session_id, int session_id_size)
{
gnutls_datum key = { session_id, session_id_size };

	return _gnutls_remove_session( session, key);
}


/* Stores session data to the db backend.
 */
int _gnutls_store_session( gnutls_session session, gnutls_datum session_id, gnutls_datum session_data)
{
int ret = 0;

	if (session->internals.resumable==RESUME_FALSE) {
		gnutls_assert();
		return GNUTLS_E_INVALID_SESSION;
	}
	
	if (_gnutls_db_func_is_ok(session)!=0) {
		return GNUTLS_E_DB_ERROR;
	}
	
	if (session_id.data==NULL || session_id.size==0) {
		gnutls_assert();
		return GNUTLS_E_INVALID_SESSION;
	}
	
	if (session_data.data==NULL || session_data.size==0) {
		gnutls_assert();
		return GNUTLS_E_INVALID_SESSION;
	}
	/* if we can't read why bother writing? */

	if (session->internals.db_store_func!=NULL)
		ret = session->internals.db_store_func( session->internals.db_ptr, session_id, session_data);

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

}

/* Retrieves session data from the db backend.
 */
gnutls_datum _gnutls_retrieve_session( gnutls_session session, gnutls_datum session_id)
{
gnutls_datum ret = { NULL, 0 };

	if (session_id.data==NULL || session_id.size==0) {
		gnutls_assert();
		return ret;
	}
	
	if (session->internals.db_retrieve_func!=NULL)
		ret = session->internals.db_retrieve_func( session->internals.db_ptr, session_id);

	return ret;

}

/* Removes session data from the db backend.
 */
int _gnutls_remove_session( gnutls_session session, gnutls_datum session_id)
{
int ret = 0;

	if (_gnutls_db_func_is_ok(session)!=0) {
		return GNUTLS_E_DB_ERROR;
	}
	
	if (session_id.data==NULL || session_id.size==0)
		return GNUTLS_E_INVALID_SESSION;

	/* if we can't read why bother writing? */
	if (session->internals.db_remove_func!=NULL)
		ret = session->internals.db_remove_func( session->internals.db_ptr, session_id);

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

}

/**
  * gnutls_db_remove_session - This function will remove the current session data from the database
  * @session: is a &gnutls_session structure.
  *
  * 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
  * abnormaly, and before gnutls_deinit() is called.
  *
  * Normally gnutls_deinit() will remove abnormally terminated sessions.
  *
  **/
void gnutls_db_remove_session(gnutls_session session) {
	/* if the session has failed abnormally it has 
	 * to be removed from the db 
	 */
	_gnutls_db_remove_session( session, session->security_parameters.session_id, session->security_parameters.session_id_size);
}