php 对输入信息的进行安全过滤的函数代码

// define constannts for input reading 
define('INPUT_GET', 0x0101); 
define('INPUT_POST', 0x0102); 
define('INPUT_GPC', 0x0103); /** 
* Read input value and convert it for internal use 
* Performs stripslashes() and charset conversion if necessary 
* 
* @param string Field name to read 
* @param int Source to get value from (GPC) 
* @param boolean Allow HTML tags in field value 
* @param string Charset to convert into 
* @return string Field value or NULL if not available 
*/ 
function get_input_value($fname, $source, $allow_html=FALSE, $charset=NULL) { 
$value = NULL; 
if ($source == INPUT_GET && isset($_GET[$fname])) 
$value = $_GET[$fname]; 
else if ($source == INPUT_POST && isset($_POST[$fname])) 
$value = $_POST[$fname]; 
else if ($source == INPUT_GPC) { 
if (isset($_POST[$fname])) 
$value = $_POST[$fname]; 
else if (isset($_GET[$fname])) 
$value = $_GET[$fname]; 
else if (isset($_COOKIE[$fname])) 
$value = $_COOKIE[$fname]; 
} 
if (empty($value)) 
return $value; 
// strip single quotes if magic_quotes_sybase is enabled 
if (ini_get('magic_quotes_sybase')) 
$value = str_replace("''", "'", $value); 
// strip slashes if magic_quotes enabled 
else if (get_magic_quotes_gpc() || get_magic_quotes_runtime()) 
$value = stripslashes($value); 
// remove HTML tags if not allowed 
if (!$allow_html) 
$value = strip_tags($value); 
// convert to internal charset 
return $value; 
}

用法：get_input_value('_uid', INPUT_GET)