[label][PHP-Security]PHP Security Program

<?php
//Example #1 Example misuse with register_globals = on

//define $authorized = true only if user is authenticated

if(authenticated_user()){
 $authorized = true;
}

// Because we didn‘t first initialize $authorized as false, this might be
// defined through register_globals, like for GET auth.php?authorized=1
// So, anyone can be seen as authenticated!
if($authorized){
　　include "hightly/sensitive/data.php";
}
?>

<?php
//Example #2 Example use of sessions with register_globals on or off

//We wouldn‘t knoe where $username came from but to know $_SESSION 
// is for session data , so We can use $_SESSION

if(isset($_SESSION[‘username‘])){
    echo ‘hello <b>{$_SESSION[‘username‘]}</b>‘; 
}else{
    echo ‘hello Guest‘;
    echo ‘Would you like to login?‘;   
}

?>

<?php
//设置报错级别，关闭错误显示，错误日志记录开启，错误日志记录保存路径
　　ini_set(‘error_reporting‘ , E_ALL | E_STRICT);

　　ini_set(‘display_errors‘ , ‘off‘);

　　ini_set(‘log_errors‘ , ‘on‘); // Start error logging

　　ini_set(‘error_log‘ , ‘/usr/local/apache/logs/error_log‘); //Saving path

//通过set_error_handler()函数来设置自己的错误处理函数 , mixed set_error_handler(callable $error_handler [,int $error_types = E_ALL | E_STRICT])

   set_error_handler(‘my_error_handler‘);    
   
   function my_error_handler(......){......}
?>

<?php
//防止跨目录

//Example #1
$file_name = $_POST[‘name‘];

str_replace( ‘..‘  , ‘.‘  , $file_name);
//这种做法是造成了其他漏洞的，当输入有3个以上点的时候，那么则一样会发生目录跳转

$file_name_2 = ‘.../.../etc/passwd‘;

echo str_replace( ‘..‘ , ‘.‘ ,$file_name_2); //输出结果为： ../../etc/passwd

//要想杜绝出现上面这种跨目录访问的情况，那么应该使用循环一直到没有‘..‘
$file_name_3 = $_POST[‘name‘];

while(strpos($file_name_3 , ‘..‘) !== false){//只要还存在跳转目录，那么就一直代替

   $file_name_3 = str_replace(‘..‘ , ‘.‘ , $file_name_3); 
}
?>

<?php
//好心办坏事的问题，那就是任何试图纠正非法数据的举动都可能斗志潜在错误并允许非法数据通过

//试图纠正非法数据的行为是错误的，只做一个更安全的检查才是更加安全的选择

//例子：客户希望用户名前后有空格则不能登录，结果修改时对用户登录程序进行了更改
//用trim()函数把输入的用户名前后的空格去掉了(这就是纠正非法数据的行为)，同时
//在注册时还是允许前后有空格，这是一个很明显的问题

//register
 if(strpos($_POST[‘register_name‘] , ‘ ‘)){ //strpos()，如果有查找的字符，那么就返回该字符的位置，没有则返回false
    echo ‘username can not have space!‘;    
}else{

   echo ‘register success.‘; 
}


//login

if(strpost($_POST[‘login_name‘] , ‘ ‘)){
    
   echo ‘Invalid username.‘;
}else{

   echo ‘login success.‘;
}
?>