CI framework security class Security.php source code analysis, cisecurity.php
The CI security class provides a global defense strategy against CSRF attacks and XSS attacks. You only need to enable it in the configuration file:
Copy code The code is as follows:
$config['csrf_protection'] = TRUE;
$config['global_xss_filtering'] = TRUE;
And provides practical methods:
Copy code The code is as follows:
$this->security->xss_clean($data);//The second parameter is TRUE to verify the security of the image
$this->security->sanitize_filename()//Filter file name
CI also provides security functions:
xss_clean()//xss filtering
sanitize_filename()//Sanitize file name
do_hash()//md5 or sha encryption
strip_image_tags() //Remove unnecessary characters of image tags
encode_php_tags()//Force PHP script tags into entity objects
Copy code The code is as follows:
/**
* Security category
*/
class CI_Security {
//Random hash value of url
protected $_xss_hash = '';
//Hash value of cookie tag to prevent CSRF attacks
protected $_csrf_hash = '';
//Anti-csrf cookie expiration time
protected $_csrf_expire = 7200;
//Csrf-proof cookie name
protected $_csrf_token_name = 'ci_csrf_token';
//Anti-csrf token name
protected $_csrf_cookie_name = 'ci_csrf_token';
//Array of strings that are not allowed
protected $_never_allowed_str = array(
'document.cookie' => '[removed]',
'document.write' => '[removed]',
'.parentNode' => '[removed]',
'.innerHTML' => '[removed]',
'window.location' => '[removed]',
'-moz-binding' => '[removed]',
'' => '-->',
' '
'
' => ''
);
//Array of regular expressions that are not allowed
protected $_never_allowed_regex = array(
'javascripts*:',
'expressions*((|()', // CSS and IE
'vbscripts*:', // IE, surprise!
'Redirects+302',
"(["'])?datas*:[^\1]*?base64[^\1]*?,[^\1]*?\1?"
);
//Constructor
public function __construct()
{
// Whether CSRF protection is enabled
if (config_item('csrf_protection') === TRUE)
{
// CSRF configuration
foreach (array('csrf_expire', 'csrf_token_name', 'csrf_cookie_name') as $key)
{
If (FALSE !== ($val = config_item($key)))
{
$this->{'_'.$key} = $val;
}
}
// _csrf_cookie_name plus cookie prefix
If (config_item('cookie_prefix'))
{
$this->_csrf_cookie_name = config_item('cookie_prefix').$this->_csrf_cookie_name;
}
//Set the hash value of csrf
$this->_csrf_set_hash();
}
log_message('debug', "Security Class Initialized");
}
//------------------------------------------------ ------------------
/**
* Verify Cross Site Request Forgery Protection
*
* @return object
*/
public function csrf_verify()
{
// If it is not a post request, set the cookie value of csrf
if (strtoupper($_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]))
{
$this->csrf_show_error();
}
//Does the token match
if ($_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;
}
//------------------------------------------------ ------------------
/**
* Set the cookie value of csrf
*/
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 $this->_csrf_token_name;
}
/**
* XSS filtering
*/
public function xss_clean($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);
$str = preg_replace_callback("/|<|$)/si", array($this, '_decode_entity'), $str);
/*
* 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 < $wordlen; $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("/![]()
{
$str = preg_replace_callback("#]*?)(s?/?>|$)#si", array($this, '_js_img_removal'), $str);
}
if (preg_match("/script/i", $str) OR preg_match("/xss/i", $str))
{
$str = preg_replace("#<(/*)(script|xss)(.*?)>#si", '[removed]', $str);
}
}
while($original != $str);
unset($original);
// Remove evil attributes such as style, onclick and xmlns
$str = $this->_remove_evil_attributes($str, $is_image);
/*
* Sanitize naughty HTML elements
*
* If a tag containing any of the words in the list
* below is found, the tag gets converted to entities.
*
* So this:
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
