MY_Session.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class MY_Session extends CI_Session{

	private $sess_use_redis = TRUE;	
	private $redis = '';

	public function __construct($params = array()) {
		//parent::__construct();
		$this->CI =& get_instance();

		foreach (array('sess_encrypt_cookie', 'sess_use_database', 'sess_table_name', 'sess_expiration', 'sess_expire_on_close', 'sess_match_ip', 'sess_match_useragent', 'sess_cookie_name', 'cookie_path', 'cookie_domain', 'cookie_secure', 'sess_time_to_update', 'time_reference', 'cookie_prefix', 'encryption_key') as $key)
		{
			$this->$key = (isset($params[$key])) ? $params[$key] : $this->CI->config->item($key);
		}

		if ($this->encryption_key == '')
		{
			show_error('In order to use the Session class you are required to set an encryption key in your config file.');
		}

		// Load the string helper so we can use the strip_slashes() function
		$this->CI->load->helper('string');

		// Do we need encryption? If so, load the encryption class
		if ($this->sess_encrypt_cookie == TRUE)
		{
			$this->CI->load->library('encrypt');
		}

		if ($this->sess_use_redis == TRUE) {
			$this->redis = new Redis();
			$this->redis->connect($this->CI->config->item('redis_host'), $this->CI->config->item('redis_port'));
			//$this->redis->setOption(Redis::OPT_SERIALIZER, Redis::SERIALIZER_PHP); //php5.4 can not work
			$this->redis->setOption(Redis::OPT_PREFIX, 'sessions:'); 
		}

		// Set the "now" time.  Can either be GMT or server time, based on the
		// config prefs.  We use this to set the "last activity" time
		$this->now = $this->_get_time();

		// Set the session length. If the session expiration is
		// set to zero we'll set the expiration two years from now.
		if ($this->sess_expiration == 0)
		{
			$this->sess_expiration = (60*60*24*365*2);
		}
		
		// Set the cookie name
		$this->sess_cookie_name = $this->cookie_prefix.$this->sess_cookie_name;

		// Run the Session routine. If a session doesn't exist we'll
		// create a new one.  If it does, we'll update it.
		if ( ! $this->sess_read()) {
			$this->sess_create();
		} else {
			$this->sess_update();
		}

		// Delete 'old' flashdata (from last request)
		$this->_flashdata_sweep();

		// Mark all new flashdata as old (data will be deleted before next request)
		$this->_flashdata_mark();

		// Delete expired sessions if necessary
		$this->_sess_gc();

		log_message('debug', "Session routines successfully run");
	}

	function sess_read() {

		$session = array();
		// Fetch the cookie
		$session_id = $this->CI->input->cookie($this->sess_cookie_name);
		// No cookie?  Goodbye cruel world!...
		if ($session_id === FALSE) {
			log_message('debug', 'A session cookie was not found.');
			return FALSE;
		}
		
		$session['session_id'] = $session_id;
		$session['ip_address'] = $this->CI->input->ip_address();	
		$session['user_agent'] = trim(substr($this->CI->input->user_agent(), 0, 120));	
				
		// Is there a corresponding session in the DB?
		if ($this->sess_use_redis=== TRUE) {
			//$this->CI->db->where('session_id', $session['session_id']);
			
			$row = json_decode($this->redis->get($session['session_id']), TRUE);
			
			if ( ! $row) {
				$this->sess_destroy();
				return FALSE;
			}

			if ($this->sess_match_ip == TRUE AND $row['ip_address']  != $session['ip_address']) {
				$this->sess_destroy();
				return FALSE;
			}

			if ($this->sess_match_useragent == TRUE AND trim($row['user_agent']) != $session['user_agent']) {
				$this->sess_destroy();
				return FALSE;
			}

			// Is there custom data?  If so, add it to the main session array
			$session['last_activity'] = $row['last_activity'];
			if (isset($row['user_data']) AND $row['user_data'] != '') {
				$custom_data = $this->_unserialize($row['user_data']);

				if (is_array($custom_data)) {
					foreach ($custom_data as $key => $val) {
						$session[$key] = $val;
					}
				}
			}
		}
		
		// Session is valid!
		$this->userdata = $session;
		unset($session);

		return TRUE;
	}

	function sess_create() {
		$sessid = '';
		while (strlen($sessid) < 32) {
			$sessid .= mt_rand(0, mt_getrandmax());
		}

		// To make the session ID even more secure we'll combine it with the user's IP
		$sessid .= $this->CI->input->ip_address();

		$this->userdata = array(
							'session_id'	=> md5(uniqid($sessid, TRUE)),
							'ip_address'	=> $this->CI->input->ip_address(),
							'user_agent'	=> substr($this->CI->input->user_agent(), 0, 120),
							'last_activity'	=> $this->now,
							'user_data'		=> ''

							);
		

		// Save the data to the DB if needed
		if ($this->sess_use_redis === TRUE) {
			$has_session = $this->redis->get($this->userdata['session_id']);
			if ($has_session) {
				$this->sess_create();
				return FALSE;
			}
			$this->redis->setex($this->userdata['session_id'], $this->sess_expiration, json_encode($this->userdata));
		}

		// Write the cookie
		$this->_set_cookie();
	}

	function sess_update() {

		// We only update the session every five minutes by default
		if (($this->userdata['last_activity'] + $this->sess_time_to_update) >= $this->now) {
			return;
		}

		// Save the old session id so we know which record to
		// update in the database if we need it
		$old_sessid = $this->userdata['session_id'];
		$new_sessid = '';
		while (strlen($new_sessid) < 32) {
			$new_sessid .= mt_rand(0, mt_getrandmax());
		}

		// To make the session ID even more secure we'll combine it with the user's IP
		$new_sessid .= $this->CI->input->ip_address();

		// Turn it into a hash
		$new_sessid = md5(uniqid($new_sessid, TRUE));
		
		// Update the session data in the session data array
		$this->userdata['session_id'] = $new_sessid;
		$this->userdata['last_activity'] = $this->now;

		// _set_cookie() will handle this for us if we aren't using database sessions
		// by pushing all userdata to the cookie.

		// Update the session ID and last_activity field in the DB if needed
			// set cookie explicitly to only have our session data
		$cookie_data = array();
		$custom_userdata = $this->userdata;
		foreach (array('session_id','ip_address','user_agent','last_activity') as $val) {
			unset($custom_userdata[$val]);
			$cookie_data[$val] = $this->userdata[$val];
		}

		if (count($custom_userdata) === 0) {
			
			$custom_userdata = '';
		} else {
			if (isset($custom_userdata['user_data'])) {
				unset($custom_userdata['user_data']);
			}
			$custom_userdata = $this->_serialize($custom_userdata);
		}

		if ($this->sess_use_redis === TRUE) {
			$has_session = $this->redis->get($new_sessid);
			if ($has_session) {
				$this->sess_update();
				return FALSE;
			}
			$this->userdata['user_data'] = $custom_userdata;	
			$this->redis->setex($new_sessid, $this->sess_expiration, json_encode($this->userdata));
			$this->redis->delete($old_sessid);
		}


		// Write the cookie
		$this->_set_cookie();
	}

	function sess_write() {
		// Are we saving custom data to the DB?  If not, all we do is update the cookie
		if ($this->sess_use_redis === FALSE) {
			$this->_set_cookie();
			return;
		}
		// set the custom userdata, the session data we will set in a second
		$custom_userdata = $this->userdata;
		$cookie_userdata = array();

		// Before continuing, we need to determine if there is any custom data to deal with.
		// Let's determine this by removing the default indexes to see if there's anything left in the array
		// and set the session data while we're at it
		foreach (array('session_id','ip_address','user_agent','last_activity') as $val) {
			unset($custom_userdata[$val]);
			$cookie_userdata[$val] = $this->userdata[$val];
		}

		// Did we find any custom data?  If not, we turn the empty array into a string
		// since there's no reason to serialize and store an empty array in the DB
			
		if (count($custom_userdata) === 0) {
			$custom_userdata = '';
		} else {
			// Serialize the custom data array so we can store it
			if (isset($custom_userdata['user_data'])) {
				unset($custom_userdata['user_data']);
			}
			$custom_userdata = $this->_serialize($custom_userdata);
		}
			
		// Run the update query
		
		$this->userdata['user_data'] = $custom_userdata;
		$this->redis->multi() 
					->delete($this->userdata['session_id'])
					->setex($this->userdata['session_id'], $this->sess_expiration, json_encode($this->userdata))
					->exec();

		// Write the cookie.  Notice that we manually pass the cookie data array to the
		// _set_cookie() function. Normally that function will store $this->userdata, but
		// in this case that array contains custom data, which we do not want in the cookie.
		$this->_set_cookie();
	}

	function _set_cookie($cookie_data = NULL) {
		
		$expire = ($this->sess_expire_on_close === TRUE) ? 0 : $this->sess_expiration + time();

		// Set the cookie
		setcookie(
					$this->sess_cookie_name,
					$this->userdata['session_id'],
					$expire,
					$this->cookie_path,
					$this->cookie_domain,
					$this->cookie_secure
				);
	}

	function _sess_gc() {
		if ($this->sess_use_redis == TRUE) {
			return;
		}
		
	}

	function sess_destroy() {
		// Kill the session DB row
		if ($this->sess_use_redis === TRUE AND isset($this->userdata['session_id'])) {
			
			$this->redis->delete($this->userdata['session_id']);
		}

		// Kill the cookie
		setcookie(
					$this->sess_cookie_name,
					addslashes(serialize(array())),
					($this->now - 31500000),
					$this->cookie_path,
					$this->cookie_domain,
					0
				);
	}
}
// END MY_Session Class

/* End of file MY_Session.php */
/* Location: ./libraries/MY_Session.php */