php过滤XSS攻击的函数

下面的函数可以用来过滤用户的输入，保证输入是XSS安全的。具体如何过滤，可以参看函数内部，也有注释。
<div class="codetitle"><a style="CURSOR: pointer" data="67943" class="copybut" id="copybut67943" onclick="doCopy('code67943')"> 代码如下:<div class="codebody" id="code67943">
<?php
function RemoveXSS($val) {
// remove all non-printable characters. CR(0a) and LF(0b) and TAB(9) are allowed
// this prevents some character re-spacing such as <javascript>
// note that you have to handle splits with n,r,and t later since they are allowed in some inputs
$val = pregreplace('/([x00-x08,x0b-x0c,x0e-x19])/','',$val); // straight replacements,the user should never need these since they're normal characters
// this prevents like <IMG SRC=@avascript:alert('XSS')>
$search = 'abcdefghijklmnopqrstuvwxyz';
$search .= 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
$search .= '1234567890!@#$%^&*()';
$search .= '~`";:?+/={}[]-|'';
for ($i = 0; $i < strlen($search); $i++) {
// ;? matches the ;,which is optional
// 0{0,7} matches any padded zeros,which are optional and go up to 8 chars // @ @ search for the hex values
$val = preg_replace('/(&#[xX]0{0,8}'.dechex(ord($search[$i])).';?)/i',$search[$i],$val); // with a ;
// @ @ 0{0,7} matches '0' zero to seven times
$val = preg_replace('/(&#0{0,8}'.ord($search[$i]).';?)/',$val); // with a ;
} // now the only remaining whitespace attacks are t,n,and r
$ra1 = Array('javascript','vbscript','expression','applet','meta','xml','blink','link','style','script','embed','object','iframe','frame','frameset','ilayer','layer','bgsound','title','base');
$ra2 = Array('onabort','onactivate','onafterprint','onafterupdate','onbeforeactivate','onbeforecopy','onbeforecut','onbeforedeactivate','onbeforeeditfocus','onbeforepaste','onbeforeprint','onbeforeunload','onbeforeupdate','onblur','onbounce','oncellchange','onchange','onclick','oncontextmenu','oncontrolselect','oncopy','oncut','ondataavailable','ondatasetchanged','ondatasetcomplete','ondblclick','ondeactivate','ondrag','ondragend','ondragenter','ondragleave','ondragover','ondragstart','ondrop','onerror','onerrorupdate','onfilterchange','onfinish','onfocus','onfocusin','onfocusout','onhelp','onkeydown','onkeypress','onkeyup','onlayoutcomplete','onload','onlosecapture','onmousedown','onmouseenter','onmouseleave','onmousemove','onmouSEOut','onmouSEOver','onmouseup','onmousewheel','onmove','onmoveend','onmovestart','onpaste','onpropertychange','onreadystatechange','onreset','onresize','onresizeend','onresizestart','onrowenter','onrowexit','onrowsdelete','onrowsinserted','onscroll','onselect','onselectionchange','onselectstart','onstart','onstop','onsubmit','onunload');
$ra = array_merge($ra1,$ra2); $found = true; // keep replacing as long as the previous round replaced something
while ($found == true) {
$val_before = $val;
for ($i = 0; $i < sizeof($ra); $i++) {
$pattern = '/';
for ($j = 0; $j < strlen($ra[$i]); $j++) {
if ($j > 0) {
$pattern .= '(';
$pattern .= '(&#[xX]0{0,8}([9ab]);)';
$pattern .= '|';
$pattern .= '|(&#0{0,8}([9|10|13]);)';
$pattern .= ')*';
}
$pattern .= $ra[$i][$j];
}
$pattern .= '/i';
$replacement = substr($ra[$i],2).''.substr($ra[$i],2); // add in <> to nerf the tag
$val = preg_replace($pattern,$replacement,$val); // filter out the hex tags
if ($val_before == $val) {
// no replacements were made,so exit the loop
$found = false;
}
}
}
return $val;
}
?>

（编辑：李大同）

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