php過濾特殊危險字元的總結

在網站中表單提交或url擷取值我們都可能碰到一些安全問題,下面我總結了一些常用的過濾一些危險特殊字元的解決方案,一般,對於傳進來的字元，php可以用addslashes函數處理一遍（要get_magic_quotes_gpc()為假才處理，不然就重複轉義了！），這樣就能達到一定程度的安全要求,比如這樣,代碼如下:

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;

}

但是還可以更進一步進行重新編碼,解碼,代碼如下:

//編碼

function htmlencode($str) {

if(emptyempty($str)) return;

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

$str=trim($str);

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

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

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

$str=str_replace(chr(32)," ",$str);

$str=str_replace(chr(9)," ",$str);

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

$str=str_replace(chr(39),"'",$str);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

return $str;

}

這樣就能更放心的對外來資料進行入庫處理了,但是從資料庫取出來,在前台顯示的時候,必須重新解碼一下,代碼如下:

//解碼

function htmldecode($str) {

if(emptyempty($str)) return;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

$str=str_replace(" ",chr(32),$str);

$str=str_replace(" ",chr(9),$str);

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

$str=str_replace("'",chr(39),$str);

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

$str=str_replace("''","'",$str); //開原始碼phpfensi.com

return $str;

}

雖然多了一步編碼,解碼的過程,但是安全方面,會更進一步,要如何做,自己取捨吧.

再附一些代碼如下:

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;

}

//更全面的代碼如下:

//處理提交的資料

function htmldecode($str) {

if (emptyempty ( $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+/", //過濾多餘的空白

"/<(//?)(img|script|i?frame|style|html|body|title|link|meta|/?|/%)([^>]*?)>/isU", //過濾 <script 防止引入惡意內容或惡意代碼,如果不需要插入flash等,還可以加入<object的過濾

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

;

$tarr = array (" ", "", //如果要直接清除不安全的標籤，這裡可以留空

"" );

return $str;

}

