CI框架安全类Security.php源码分析，cisecurity.php

CI安全类提供了全局防御CSRF攻击和XSS攻击策略，只需要在配置文件开启即可：

复制代码代码如下:

$config['csrf_protection'] = TRUE;
$config['global_xss_filtering'] = TRUE;

并提供了实用方法：

复制代码代码如下:

$this->security->xss_clean($data);//第二个参数为TRUE，验证图片安全
$this->security->sanitize_filename()//过滤文件名

CI也提供了安全函数：

xss_clean()//xss过滤
sanitize_filename()//净化文件名
do_hash()//md5或sha加密
strip_image_tags() //删除图片标签的不必要字符
encode_php_tags()//把PHP脚本标签强制转成实体对象

复制代码代码如下:

/**
* 安全类
*/
class CI_Security {
//url的随机hash值
protected $_xss_hash   = '';
//防csrf攻击的cookie标记的哈希值
protected $_csrf_hash   = '';
//防csrf cookie过期时间
protected $_csrf_expire   = 7200;
//防csrf的cookie名称
protected $_csrf_token_name  = 'ci_csrf_token';
//防csrf的token名称
protected $_csrf_cookie_name = 'ci_csrf_token';
//不允许出现的字符串数组
protected $_never_allowed_str = array(
  'document.cookie' => '[removed]',
  'document.write' => '[removed]',
  '.parentNode'  => '[removed]',
  '.innerHTML'  => '[removed]',
  'window.location' => '[removed]',
  '-moz-binding'  => '[removed]',
  ''    => '-->',
  ' '   ''   => ''
);
//不允许出现的正则表达式数组
protected $_never_allowed_regex = array(
  'javascript\s*:',
  'expression\s*(\(|&\#40;)', // CSS and IE
  'vbscript\s*:', // IE, surprise!
  'Redirect\s+302',
  "([\"'])?data\s*:[^\\1]*?base64[^\\1]*?,[^\\1]*?\\1?"
);
//构造函数
public function __construct()
{
  // CSRF保护是否开启
  if (config_item('csrf_protection') === TRUE)
  {
   // CSRF配置
   foreach (array('csrf_expire', 'csrf_token_name', 'csrf_cookie_name') as $key)
   {
    if (FALSE !== ($val = config_item($key)))
    {
     $this->{'_'.$key} = $val;
    }
   }
   // _csrf_cookie_name加上cookie前缀
   if (config_item('cookie_prefix'))
   {
    $this->_csrf_cookie_name = config_item('cookie_prefix').$this->_csrf_cookie_name;
   }
   // 设置csrf的hash值
   $this->_csrf_set_hash();
  }
  log_message('debug', "Security Class Initialized");
}
// --------------------------------------------------------------------
/**
* Verify Cross Site Request Forgery Protection
*
* @return object
*/
public function csrf_verify()
{
  // 如果不是post请求，则设置csrf的cookie值
  if (strtoupper($_SERVER['REQUEST_METHOD']) !== 'POST')
  {
   return $this->csrf_set_cookie();
  }
  // Do the tokens exist in both the _POST and _COOKIE arrays?
  if ( ! isset($_POST[$this->_csrf_token_name], $_COOKIE[$this->_csrf_cookie_name]))
  {
   $this->csrf_show_error();
  }
  // token匹配吗
  if ($_POST[$this->_csrf_token_name] != $_COOKIE[$this->_csrf_cookie_name])
  {
   $this->csrf_show_error();
  }
  // We kill this since we're done and we don't want to
  // polute the _POST array
  unset($_POST[$this->_csrf_token_name]);
  // Nothing should last forever
  unset($_COOKIE[$this->_csrf_cookie_name]);
  $this->_csrf_set_hash();
  $this->csrf_set_cookie();
  log_message('debug', 'CSRF token verified');
  return $this;
}
// --------------------------------------------------------------------
/**
* 设置csrf的cookie值
*/
public function csrf_set_cookie()
{
  $expire = time() + $this->_csrf_expire;
  $secure_cookie = (config_item('cookie_secure') === TRUE) ? 1 : 0;
  if ($secure_cookie && (empty($_SERVER['HTTPS']) OR strtolower($_SERVER['HTTPS']) === 'off'))
  {
   return FALSE;
  }
  setcookie($this->_csrf_cookie_name, $this->_csrf_hash, $expire, config_item('cookie_path'), config_item('cookie_domain'), $secure_cookie);
  log_message('debug', "CRSF cookie Set");
  return $this;
}
//csrf保存
public function csrf_show_error()
{
  show_error('The action you have requested is not allowed.');
}
//获取csrf的hash值
public function get_csrf_hash()
{
  return $this->_csrf_hash;
}
//获取csrf的token值
public function get_csrf_token_name()
{
  return $this->_csrf_token_name;
}
/**
* XSS 过滤
*/
public function xss_clean($str, $is_image = FALSE)
{
  //是否是数组
  if (is_array($str))
  {
   while (list($key) = each($str))
   {
    $str[$key] = $this->xss_clean($str[$key]);
   }
   return $str;
  }
  //去掉可见字符串
  $str = remove_invisible_characters($str);
  // 验证实体url
  $str = $this->_validate_entities($str);
  /*
   * URL 解码
   *
   * Just in case stuff like this is submitted:
   *
   * Google
   *
   * Note: Use rawurldecode() so it does not remove plus signs
   *
   */
  $str = rawurldecode($str);
  /*
   * Convert character entities to ASCII
   *
   * This permits our tests below to work reliably.
   * We only convert entities that are within tags since
   * these are the ones that will pose security problems.
   *
   */
  $str = preg_replace_callback("/[a-z]+=([\'\"]).*?\\1/si", array($this, '_convert_attribute'), $str);
  $str = preg_replace_callback("/|   /*
   * Remove Invisible Characters Again!
   */
  $str = remove_invisible_characters($str);
  /*
   * Convert all tabs to spaces
   *
   * This prevents strings like this: ja vascript
   * NOTE: we deal with spaces between characters later.
   * NOTE: preg_replace was found to be amazingly slow here on
   * large blocks of data, so we use str_replace.
   */
  if (strpos($str, "\t") !== FALSE)
  {
   $str = str_replace("\t", ' ', $str);
  }
  /*
   * Capture converted string for later comparison
   */
  $converted_string = $str;
  // Remove Strings that are never allowed
  $str = $this->_do_never_allowed($str);
  /*
   * Makes PHP tags safe
   *
   * Note: XML tags are inadvertently replaced too:
   *
   *    *
   * But it doesn't seem to pose a problem.
   */
  if ($is_image === TRUE)
  {
   // Images have a tendency to have the PHP short opening and
   // closing tags every so often so we skip those and only
   // do the long opening tags.
   $str = preg_replace('/   }
  else
  {
   $str = str_replace(array(''), array(''), $str);
  }
  /*
   * Compact any exploded words
   *
   * This corrects words like: j a v a s c r i p t
   * These words are compacted back to their correct state.
   */
  $words = array(
   'javascript', 'expression', 'vbscript', 'script', 'base64',
   'applet', 'alert', 'document', 'write', 'cookie', 'window'
  );
  foreach ($words as $word)
  {
   $temp = '';
   for ($i = 0, $wordlen = strlen($word); $i    {
    $temp .= substr($word, $i, 1)."\s*";
   }
   // We only want to do this when it is followed by a non-word character
   // That way valid stuff like "dealer to" does not become "dealerto"
   $str = preg_replace_callback('#('.substr($temp, 0, -3).')(\W)#is', array($this, '_compact_exploded_words'), $str);
  }
  /*
   * Remove disallowed Javascript in links or img tags
   * We used to do some version comparisons and use of stripos for PHP5,
   * but it is dog slow compared to these simplified non-capturing
   * preg_match(), especially if the pattern exists in the string
   */
  do
  {
   $original = $str;
   if (preg_match("/    {
    $str = preg_replace_callback("#]*?)(>|$)#si", array($this, '_js_link_removal'), $str);
   }
   if (preg_match("/ CI框架安全类Security.php源码分析，cisecurity.php_PHP教程

{
$str = preg_replace_callback("# CI框架安全类Security.php源码分析，cisecurity.php_PHP教程

CI框架自带的Loder类

很久不用CI了。
我记得好像是：
APPPATH是你自己扩展的类，在application/libraries下
BASEPATH是框架自带的类，在system/libraries下
当你$this->load->library();时先看你自己是否有扩展，如果没有扩展就使用CI框架的，如果BASEPATH路径下面不存在时（指的是CI基础类），就会报错的。一般情况下application/libraries里面的扩展类会用到system/libraries里面的基础类。