php過濾特殊危險字符的總結

php過濾特殊危險字符的總結

一般，對於傳進來的字符，php教程可以用addslashes函數處理一遍（要get_magic_quotes_gpc()為假才處理，不然就重復轉義了！），這樣就能達到一定程度的安全要求
比如這樣


代碼如下 復制代碼
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，如下：


代碼如下 復制代碼
//編碼


function htmlencode($str) {
if(empty($str)) return;
if($str=="") return $str;
$str=trim($str);
$str=str_replace("&","&",$str);
$str=str_replace(">",">",$str);
$str=str_replace("<","<",$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數據進行入庫處理了， 但是從數據庫取出來，在前台顯示的時候，必須重新解碼一下：


代碼如下 復制代碼
//解碼


function htmldecode($str) {
if(empty($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);
$str=str_replace((www.111cn.net)"modify","modify",$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);
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 復制代碼
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 復制代碼
//處理提交的數據
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+/", //過濾多余的空白
"/<(//?)(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]*)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簽，這裡可以留空
"" );
return $str;
}

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