關於CI架構中Session.php源碼分析

這篇文章主要介紹了關於CI架構中Session.php源碼分析，有著一定的參考價值，現在分享給大家，有需要的朋友可以參考一下

Session類並不使用PHP本身的session，而是使用類自己的session，這樣做，可以給開發人員提供更大的彈性。下面我們就來仔細分析下CI架構的Session類Session.php檔案

CI的Session並不是原生的session，正是我前面所有的cookie based session,另外，CI可以根據使用者選擇配置是否將session存入資料庫中，本人很喜歡這個功能，還有就是“閃出資料”的功能，既閃出資料只是對下次伺服器請求可以，之後就會被自動清除。常見使用方法有：

$this->session->set_userdata('some_name', 'some_value'); //設定session資料

$this->session->userdata('item'); //擷取session資料

$this->session->unset_userdata('some_name'); //刪除session資料

$this->session->sess_destroy(); //銷毀session資料

$this->session->set_flashdata('item', 'value'); //設定快閃記憶體資料

$this->session->flashdata('item'); //擷取快閃記憶體資料

$this->session->keep_flashdata('item');  //保留快閃記憶體資料

/** * CI是 session based cookie */class CI_Session { var $sess_encrypt_cookie  = FALSE;  //是否對session加密 var $sess_use_database   = FALSE; //是否將session存入資料庫 var $sess_table_name   = ''; //session存入資料的表名 var $sess_expiration   = 7200; //session的到期時間 var $sess_expire_on_close  = FALSE; //當瀏覽器視窗關閉時是否自動使session到期 var $sess_match_ip    = FALSE;//是否通過使用者的IP地址來讀取 session 的資料 var $sess_match_useragent  = TRUE; //是否要按照對應的 User Agent 來讀取 session 資料。 var $sess_cookie_name   = 'ci_session'; //cookie名稱 var $cookie_prefix    = ''; //cookie首碼 var $cookie_path    = ''; //cookie路徑 var $cookie_domain    = ''; //cookie範圍 var $cookie_secure    = FALSE; //是否在安全的https協議下才有效 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(); //使用者session資料儲存變數 var $CI; //CI超級控制代碼 var $now;  //目前時間 public function __construct($params = array()) {  log_message('debug', "Session Class Initialized");  // 擷取CI超級類  $this->CI =& get_instance();  // 擷取config檔案中的配置資料  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);  }                //必須設定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.');  }  // 載入string helper函數  $this->CI->load->helper('string');  // D如果對cookie進行加密，則引入加密類  if ($this->sess_encrypt_cookie == TRUE)  {   $this->CI->load->library('encrypt');  }  // 如果session計入資料庫，則引入db  if ($this->sess_use_database === TRUE AND $this->sess_table_name != '')  {   $this->CI->load->database();  }  // 擷取目前時間  $this->now = $this->_get_time();  // 如果沒有設定session的有效時間，預設兩年  if ($this->sess_expiration == 0)  {   $this->sess_expiration = (60*60*24*365*2);  }  // 擷取cookie名稱  $this->sess_cookie_name = $this->cookie_prefix.$this->sess_cookie_name;  // 如果session不存在，建立新會話  if ( ! $this->sess_read())  {   $this->sess_create();  }  else  {   $this->sess_update();  }  // 閃出標記old的閃出資料  $this->_flashdata_sweep();                //將新的閃出資料標記成old 標記成old的資料的資料將會在下次請求時閃出  $this->_flashdata_mark();  //回收/刪除 到期的session  $this->_sess_gc();  log_message('debug', "Session routines successfully run"); } // -------------------------------------------------------------------- /**  * 讀取session資料  */ function sess_read() {  // 擷取session  $session = $this->CI->input->cookie($this->sess_cookie_name);  // 沒有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;   }  }  // 還原序列化存入cookie的session數組  $session = $this->_unserialize($session);  // 檢測session的資料  if ( ! is_array($session) OR ! isset($session['session_id']) OR ! isset($session['ip_address']) OR ! isset($session['user_agent']) OR ! isset($session['last_activity']))  {   $this->sess_destroy();   return FALSE;  }  // session資料到期了嗎  if (($session['last_activity'] + $this->sess_expiration) < $this->now)  {   $this->sess_destroy();   return FALSE;  }  // 是否是根據使用者ip來讀取session資料  if ($this->sess_match_ip == TRUE AND $session['ip_address'] != $this->CI->input->ip_address())  {   $this->sess_destroy();   return FALSE;  }  // 是否根據ua來匹配session資料  if ($this->sess_match_useragent == TRUE AND trim($session['user_agent']) != trim(substr($this->CI->input->user_agent(), 0, 120)))  {   $this->sess_destroy();   return FALSE;  }  // 如果session入庫了，這種方式應該更安全點，當然負載大時，就不建議了，資料庫讀寫壓力大  if ($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; } // -------------------------------------------------------------------- /**  * 將讀取的session資料寫入  */ function sess_write() {  // 是否寫入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記錄  $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); } // -------------------------------------------------------------------- /**  * 建立一個新的session  */ function sess_create() {                //保證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  $this->_set_cookie(); } // -------------------------------------------------------------------- /**  * 更新session  */ function sess_update() {  // 預設五分鐘更新  if (($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.  $cookie_data = NULL;  // 更新資料庫中幾率  if ($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)));  }  // 重新寫入session  $this->_set_cookie($cookie_data); } // -------------------------------------------------------------------- /**  *銷毀當前所有session資料  */ 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  $this->userdata = array(); } // -------------------------------------------------------------------- /**  * 擷取session數組指定元素的值  */ function userdata($item) {  return ( ! isset($this->userdata[$item])) ? FALSE : $this->userdata[$item]; } // -------------------------------------------------------------------- /**  * 擷取所有session資料  */ function all_userdata() {  return $this->userdata; } // -------------------------------------------------------------------- /**  * 添加和修改自訂的session資料  */ function set_userdata($newdata = array(), $newval = '') {  if (is_string($newdata))  {   $newdata = array($newdata => $newval);  }                //支援數組組合方式  if (count($newdata) > 0)  {   foreach ($newdata as $key => $val)   {    $this->userdata[$key] = $val;   }  }  $this->sess_write(); } // -------------------------------------------------------------------- /**  * 刪除session數組中的元素，  */ function unset_userdata($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, $val);   }  } } // ------------------------------------------------------------------------ /**  * CI支援閃出資料也就是說 Session資料只對下次伺服器請求可用,有時候如果你還想在下個請求後的請求還有效。。。         * keep_flashdata功能就是講持續保持閃出資料，使其在下個請求也有效  */ function keep_flashdata($key) {                //將閃出資料標記成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, $value); } // ------------------------------------------------------------------------ /**  * 擷取閃出資料  */ function flashdata($key) {  $flashdata_key = $this->flashdata_key.':old:'.$key;  return $this->userdata($flashdata_key); } // ------------------------------------------------------------------------ /**  * 將閃出資料標記成old，以便_flashdata_sweep清除資料  */ 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);   }  } } // ------------------------------------------------------------------------ /**  * 將標記成old的閃出資料閃出  */ function _flashdata_sweep() {  $userdata = $this->all_userdata();  foreach ($userdata as $key => $value)  {   if (strpos($key, ':old:'))   {    $this->unset_userdata($key);   }  } } //擷取目前時間 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 $time; } // -------------------------------------------------------------------- /**  * 寫入session cookie  *  */ function _set_cookie($cookie_data = NULL) {  if (is_null($cookie_data))  {   $cookie_data = $this->userdata;  }  // 序列化數組  $cookie_data = $this->_serialize($cookie_data);                //加密資料  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為TRUE則，瀏覽器關閉，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,     $this->cookie_secure    ); } // -------------------------------------------------------------------- /**  * 序列化數組  */ function _serialize($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); } // -------------------------------------------------------------------- /**  * 還原序列化數組  */ 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) : $data; } // -------------------------------------------------------------------- /**  * 回收/刪除資料庫中失效的session資訊  */ function _sess_gc() {  if ($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.');  } }}

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