php过滤特殊危险字符的总结

一般，对于传进来的字符，php教程可以用addslashes函数处理一遍（要get_magic_quotes_gpc()为假才处理，不然就重复转义了！），这样就能达到一定程度的安全要求

比如这样

代码如下 复制代码

if (!get_magic_quotes_gpc()) {

add_slashes($_GET);

add_slashes($_POST);

add_slashes($_COOKIE);

}

function add_slashes($string) {

if (is_array($string)) {

foreach ($string as $key => $value) {

$string[$key] = add_slashes($value);

}

} else {

$string = addslashes($string);

}

return $string;

}

但是还可以更进一步进行重新编码，解码，如下：

代码如下 复制代码

//编码

function htmlencode($str) {

if(empty($str)) return;

if($str=="") return $str;

$str=trim($str);

$str=str_replace("&","&",$str);

$str=str_replace(">",">",$str);

$str=str_replace("<","&lt;",$str);

$str=str_replace(chr(32),"&nbsp;",$str);

$str=str_replace(chr(9),"&nbsp;",$str);

$str=str_replace(chr(34),"&",$str);

$str=str_replace(chr(39),"&#39;",$str);

$str=str_replace(chr(13),"<br />",$str);

$str=str_replace("'","''",$str);

$str=str_replace("select","sel&#101;ct",$str);

$str=str_replace("join","jo&#105;n",$str);

$str=str_replace("union","un&#105;on",$str);

$str=str_replace("where","wh&#101;re",$str);

$str=str_replace("insert","ins&#101;rt",$str);

$str=str_replace("delete","del&#101;te",$str);

$str=str_replace("update","up&#100;ate",$str);

$str=str_replace("like","lik&#101;",$str);

$str=str_replace("drop","dro&#112;",$str);

$str=str_replace("create","cr&#101;ate",$str);

$str=str_replace("modify","mod&#105;fy",$str);

$str=str_replace("rename","ren&#097;me",$str);

$str=str_replace("alter","alt&#101;r",$str);

$str=str_replace("cast","ca&#115;",$str);

return $str;

}

这样就能更放心的对外来数据进行入库处理了， 但是从数据库取出来，在前台显示的时候，必须重新解码一下：

代码如下 复制代码

//解码

function htmldecode($str) {

if(empty($str)) return;

if($str=="") return $str;

$str=str_replace("sel&#101;ct","select",$str);

$str=str_replace("jo&#105;n","join",$str);

$str=str_replace("un&#105;on","union",$str);

$str=str_replace("wh&#101;re","where",$str);

$str=str_replace("ins&#101;rt","insert",$str);

$str=str_replace("del&#101;te","delete",$str);

$str=str_replace("up&#100;ate","update",$str);

$str=str_replace("lik&#101;","like",$str);

$str=str_replace("dro&#112;","drop",$str);

$str=str_replace("cr&#101;ate","create",$str);

$str=str_replace((www.111cn.net)"mod&#105;fy","modify",$str);

$str=str_replace("ren&#097;me","rename",$str);

$str=str_replace("alt&#101;r","alter",$str);

$str=str_replace("ca&#115;","cast",$str);

$str=str_replace("&amp;","&",$str);

$str=str_replace("&gt;",">",$str);

$str=str_replace("&lt;","<",$str);

$str=str_replace("&nbsp;",chr(32),$str);

$str=str_replace("&nbsp;",chr(9),$str);

$str=str_replace("&",chr(34),$str);

$str=str_replace("&#39;",chr(39),$str);

$str=str_replace("<br />",chr(13),$str);

$str=str_replace("''","'",$str);

return $str;

}

虽然多了一步编码，解码的过程，但是安全方面，会更进一步，要如何做，自己取舍吧。

再附一些

代码如下 复制代码

function safe_replace($string) {

$string = str_replace(' ','',$string);

$string = str_replace(''','',$string);

$string = str_replace(''','',$string);

$string = str_replace('*','',$string);

$string = str_replace('"','"',$string);

$string = str_replace("'",'',$string);

$string = str_replace('"','',$string);

$string = str_replace(';','',$string);

$string = str_replace('<','<',$string);

$string = str_replace('>','>',$string);

$string = str_replace("{",'',$string);

$string = str_replace('}','',$string);

return $string;

}

更全面的

代码如下 复制代码

//处理提交的数据

function htmldecode($str) {

if (empty ( $str ) || "" == $str) {

return "";

}

$str = strip_tags ( $str );

$str = htmlspecialchars ( $str );

$str = nl2br ( $str );

$str = str_replace ( "?", "", $str );

$str = str_replace ( "*", "", $str );

$str = str_replace ( "!", "", $str );

$str = str_replace ( "~", "", $str );

$str = str_replace ( "$", "", $str );

$str = str_replace ( "%", "", $str );

$str = str_replace ( "^", "", $str );

$str = str_replace ( "^", "", $str );

$str = str_replace ( "select", "", $str );

$str = str_replace ( "join", "", $str );

$str = str_replace ( "union", "", $str );

$str = str_replace ( "where", "", $str );

$str = str_replace ( "insert", "", $str );

$str = str_replace ( "delete", "", $str );

$str = str_replace ( "update", "", $str );

$str = str_replace ( "like", "", $str );

$str = str_replace ( "drop", "", $str );

$str = str_replace ( "create", "", $str );

$str = str_replace ( "modify", "", $str );

$str = str_replace ( "rename", "", $str );

$str = str_replace ( "alter", "", $str );

$str = str_replace ( "cast", "", $str );

$farr = array ("//s+/", //过滤多余的空白

"/<(//?)(img|script|i?frame|style|html|body|title|link|meta|/?|/%)([^>]*?)>/isU", //过滤 <script 防止引入恶意内容或恶意代码,如果不需要插入flash等,还可以加入<object的过滤

"/(<[^>]*)on[a-zA-Z]+/s*=([^>]*>)/isU" )//过滤javascript的on事件

;

$tarr = array (" ", "", //如果要直接清除不安全的标签，这里可以留空

"" );

return $str;

}

from:http://www.111cn.net/phper/phpanqn/55876.htm