/**  * CI是 session based cookie  */ class CI_Session {  var $sess_encrypt_cookie  = FALSE;  //是否对session加密  var $sess_use_database   = FALSE; //是否将session存入数据库  var $sess_table_name   = ''; //session存入数据的表名  var $sess_expiration   = 7200; //session的过期时间  var $sess_expire_on_close  = FALSE; //当浏览器窗口关闭时是否自动使session过期  var $sess_match_ip    = FALSE;//是否通过用户的IP地址来读取 session 的数据  var $sess_match_useragent  = TRUE; //是否要按照对应的 User Agent 来读取 session 数据。  var $sess_cookie_name   = 'ci_session'; //cookie名称  var $cookie_prefix    = ''; //cookie前缀  var $cookie_path    = ''; //cookie路径  var $cookie_domain    = ''; //cookie作用域  var $cookie_secure    = FALSE; //是否在安全的https协议下才有效  var $sess_time_to_update  = 300; //session cookie多久更新一次  var $encryption_key    = ''; //加密key  var $flashdata_key    = 'flash';  var $time_reference    = 'time';  var $gc_probability    = 5;  //回收session的能力  var $userdata     = array(); //用户session数据保存变量  var $CI; //CI超级句柄  var $now;  //当前时间  public function __construct($params = array())  {   log_message('debug', "Session Class Initialized");   // 获取CI超级类   $this->CI =& get_instance();   // 获取config文件中的配置数据   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);   }                 //必须设置encryption_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.');   }   // 加载string helper函数   $this->CI->load->helper('string');   // D如果对cookie进行加密，则引入加密类   if ($this->sess_encrypt_cookie == TRUE)   {    $this->CI->load->library('encrypt');   }   // 如果session计入数据库，则引入db   if ($this->sess_use_database === TRUE AND $this->sess_table_name != '')   {    $this->CI->load->database();   }   // 获取当前时间   $this->now = $this->_get_time();   // 如果没有设置session的有效时间，默认两年   if ($this->sess_expiration == 0)   {    $this->sess_expiration = (60*60*24*365*2);   }   // 获取cookie名称   $this->sess_cookie_name = $this->cookie_prefix.$this->sess_cookie_name;   // 如果session不存在，创建新会话   if ( ! $this->sess_read())   {    $this->sess_create();   }   else   {    $this->sess_update();   }   // 闪出标记old的闪出数据   $this->_flashdata_sweep();                 //将新的闪出数据标记成old 标记成old的数据的数据将会在下次请求时闪出   $this->_flashdata_mark();   //回收/删除 过期的session   $this->_sess_gc();   log_message('debug', "Session routines successfully run");  }  // --------------------------------------------------------------------  /**   * 读取session数据   */  function sess_read()  {   // 获取session   $session = $this->CI->input->cookie($this->sess_cookie_name);   // 没有session  拜拜   if ($session === FALSE)   {    log_message('debug', 'A session cookie was not found.');    return FALSE;   }   // 如果加密了cookie   if ($this->sess_encrypt_cookie == TRUE)   {    $session = $this->CI->encrypt->decode($session);   }   else   {    // encryption was not used, so we need to check the md5 hash    $hash  = substr($session, strlen($session)-32); // get last 32 chars    $session = substr($session, 0, strlen($session)-32);    // Does the md5 hash match?  This is to prevent manipulation of session data in userspace    if ($hash !==  md5($session.$this->encryption_key))    {     log_message('error', 'The session cookie data did not match what was expected. This could be a possible hacking attempt.');     $this->sess_destroy();     return FALSE;    }   }   // 反序列化存入cookie的session数组   $session = $this->_unserialize($session);   // 检测session的数据   if ( ! is_array($session) OR ! isset($session['session_id']) OR ! isset($session['ip_address']) OR ! isset($session['user_agent']) OR ! isset($session['last_activity']))   {    $this->sess_destroy();    return FALSE;   }   // session数据过期了吗   if (($session['last_activity'] + $this->sess_expiration) < $this->now)   {    $this->sess_destroy();    return FALSE;   }   // 是否是根据用户ip来读取session数据   if ($this->sess_match_ip == TRUE AND $session['ip_address'] != $this->CI->input->ip_address())   {    $this->sess_destroy();    return FALSE;   }   // 是否根据ua来匹配session数据   if ($this->sess_match_useragent == TRUE AND trim($session['user_agent']) != trim(substr($this->CI->input->user_agent(), 0, 120)))   {    $this->sess_destroy();    return FALSE;   }   // 如果session入库了，这种方式应该更安全点，当然负载大时，就不建议了，数据库读写压力大   if ($this->sess_use_database === TRUE)   {    $this->CI->db->where('session_id', $session['session_id']);    if ($this->sess_match_ip == TRUE)    {     $this->CI->db->where('ip_address', $session['ip_address']);    }    if ($this->sess_match_useragent == TRUE)    {     $this->CI->db->where('user_agent', $session['user_agent']);    }    $query = $this->CI->db->get($this->sess_table_name);    // No result?  Kill it!    if ($query->num_rows() == 0)    {     $this->sess_destroy();     return FALSE;    }    // Is there custom data?  If so, add it to the main session array    $row = $query->row();    if (isset($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;  }  // --------------------------------------------------------------------  /**   * 将读取的session数据写入   */  function sess_write()  {   // 是否写入db   if ($this->sess_use_database === 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    $custom_userdata = $this->_serialize($custom_userdata);   }   // 更新session记录   $this->CI->db->where('session_id', $this->userdata['session_id']);   $this->CI->db->update($this->sess_table_name, array('last_activity' => $this->userdata['last_activity'], 'user_data' => $custom_userdata));   // 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.   $this->_set_cookie($cookie_userdata);  }  // --------------------------------------------------------------------  /**   * 创建一个新的session   */  function sess_create()  {                 //保证sessid 安全唯一   $sessid = '';   while (strlen($sessid) < 32)   {    $sessid .= mt_rand(0, mt_getrandmax());   }   $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_database === TRUE)   {    $this->CI->db->query($this->CI->db->insert_string($this->sess_table_name, $this->userdata));   }   // Write the cookie   $this->_set_cookie();  }  // --------------------------------------------------------------------  /**   * 更新session   */  function sess_update()  {   // 默认五分钟更新   if (($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.   $cookie_data = NULL;   // 更新数据库中几率   if ($this->sess_use_database === TRUE)   {    // set cookie explicitly to only have our session data    $cookie_data = array();    foreach (array('session_id','ip_address','user_agent','last_activity') as $val)    {     $cookie_data[$val] = $this->userdata[$val];    }    $this->CI->db->query($this->CI->db->update_string($this->sess_table_name, array('last_activity' => $this->now, 'session_id' => $new_sessid), array('session_id' => $old_sessid)));   }   // 重新写入session   $this->_set_cookie($cookie_data);  }  // --------------------------------------------------------------------  /**   *销毁当前所有session数据   */  function sess_destroy()  {   // Kill the session DB row   if ($this->sess_use_database === TRUE && isset($this->userdata['session_id']))   {    $this->CI->db->where('session_id', $this->userdata['session_id']);    $this->CI->db->delete($this->sess_table_name);   }   // Kill the cookie   setcookie(      $this->sess_cookie_name,      addslashes(serialize(array())),      ($this->now - 31500000),      $this->cookie_path,      $this->cookie_domain,      0     );   // Kill session data   $this->userdata = array();  }  // --------------------------------------------------------------------  /**   * 获取session数组指定元素的值   */  function userdata($item)  {   return ( ! isset($this->userdata[$item])) ? FALSE : $this->userdata[$item];  }  // --------------------------------------------------------------------  /**   * 获取所有session数据   */  function all_userdata()  {   return $this->userdata;  }  // --------------------------------------------------------------------  /**   * 添加和修改自定义的session数据   */  function set_userdata($newdata = array(), $newval = '')  {   if (is_string($newdata))   {    $newdata = array($newdata => $newval);   }                 //支持数组组合方式   if (count($newdata) > 0)   {    foreach ($newdata as $key => $val)    {     $this->userdata[$key] = $val;    }   }   $this->sess_write();  }  // --------------------------------------------------------------------  /**   * 删除session数组中的元素，   */  function unset_userdata($newdata = array())  {   if (is_string($newdata))   {    $newdata = array($newdata => '');   }   if (count($newdata) > 0)   {    foreach ($newdata as $key => $val)    {     unset($this->userdata[$key]);    }   }   $this->sess_write();  }  // ------------------------------------------------------------------------  /**   * Add or change flashdata, only available   * until the next request   *   * @access public   * @param mixed   * @param string   * @return void   */  function set_flashdata($newdata = array(), $newval = '')  {   if (is_string($newdata))   {    $newdata = array($newdata => $newval);   }   if (count($newdata) > 0)   {    foreach ($newdata as $key => $val)    {     $flashdata_key = $this->flashdata_key.':new:'.$key;     $this->set_userdata($flashdata_key, $val);    }   }  }  // ------------------------------------------------------------------------  /**   * CI支持闪出数据也就是说 Session数据只对下次服务器请求可用,有时候如果你还想在下个请求后的请求还有效。。。          * keep_flashdata功能就是讲持续保持闪出数据，使其在下个请求也有效   */  function keep_flashdata($key)  {                 //将闪出数据标记成new   $old_flashdata_key = $this->flashdata_key.':old:'.$key;   $value = $this->userdata($old_flashdata_key);   $new_flashdata_key = $this->flashdata_key.':new:'.$key;   $this->set_userdata($new_flashdata_key, $value);  }  // ------------------------------------------------------------------------  /**   * 获取闪出数据   */  function flashdata($key)  {   $flashdata_key = $this->flashdata_key.':old:'.$key;   return $this->userdata($flashdata_key);  }  // ------------------------------------------------------------------------  /**   * 将闪出数据标记成old，以便_flashdata_sweep清除数据   */  function _flashdata_mark()  {   $userdata = $this->all_userdata();   foreach ($userdata as $name => $value)   {    $parts = explode(':new:', $name);    if (is_array($parts) && count($parts) === 2)    {     $new_name = $this->flashdata_key.':old:'.$parts[1];     $this->set_userdata($new_name, $value);     $this->unset_userdata($name);    }   }  }  // ------------------------------------------------------------------------  /**   * 将标记成old的闪出数据闪出   */  function _flashdata_sweep()  {   $userdata = $this->all_userdata();   foreach ($userdata as $key => $value)   {    if (strpos($key, ':old:'))    {     $this->unset_userdata($key);    }   }  }  //获取当前时间  function _get_time()  {   if (strtolower($this->time_reference) == 'gmt')   {    $now = time();    $time = mktime(gmdate("H", $now), gmdate("i", $now), gmdate("s", $now), gmdate("m", $now), gmdate("d", $now), gmdate("Y", $now));   }   else   {    $time = time();   }   return $time;  }  // --------------------------------------------------------------------  /**   * 写入session cookie   *   */  function _set_cookie($cookie_data = NULL)  {   if (is_null($cookie_data))   {    $cookie_data = $this->userdata;   }   // 序列化数组   $cookie_data = $this->_serialize($cookie_data);                 //加密数据   if ($this->sess_encrypt_cookie == TRUE)   {    $cookie_data = $this->CI->encrypt->encode($cookie_data);   }   else   {    // if encryption is not used, we provide an md5 hash to prevent userside tampering    $cookie_data = $cookie_data.md5($cookie_data.$this->encryption_key);   }                 //sess_expire_on_close为TRUE则，浏览器关闭，session失效   $expire = ($this->sess_expire_on_close === TRUE) ? 0 : $this->sess_expiration + time();   // Set the cookie   setcookie(      $this->sess_cookie_name,      $cookie_data,      $expire,      $this->cookie_path,      $this->cookie_domain,      $this->cookie_secure     );  }  // --------------------------------------------------------------------  /**   * 序列化数组   */  function _serialize($data)  {   if (is_array($data))   {    foreach ($data as $key => $val)    {     if (is_string($val))     {      $data[$key] = str_replace('\\', '{{slash}}', $val);     }    }   }   else   {    if (is_string($data))    {     $data = str_replace('\\', '{{slash}}', $data);    }   }   return serialize($data);  }  // --------------------------------------------------------------------  /**   * 反序列化数组   */  function _unserialize($data)  {   $data = @unserialize(strip_slashes($data));   if (is_array($data))   {    foreach ($data as $key => $val)    {     if (is_string($val))     {      $data[$key] = str_replace('{{slash}}', '\\', $val);     }    }    return $data;   }   return (is_string($data)) ? str_replace('{{slash}}', '\\', $data) : $data;  }  // --------------------------------------------------------------------  /**   * 回收/删除数据库中失效的session信息   */  function _sess_gc()  {   if ($this->sess_use_database != TRUE)   {    return;   }   srand(time());   if ((rand() % 100) < $this->gc_probability)   {    $expire = $this->now - $this->sess_expiration;    $this->CI->db->where("last_activity < {$expire}");    $this->CI->db->delete($this->sess_table_name);    log_message('debug', 'Session garbage collection performed.');   }  } }