Prevent script from running again in php

Question

I have a script to give a unique download link. Below:

The problem is when i refresh the page it generates another link.

i tried header but i want to:

Show the unique download link
If refresh page, redirect or echo 'Only one download per IP!

Something like that. The code is

<?php

//connect to the DB
$resDB = mysql_connect("sql213.byethost10.com", "user", "pass");
mysql_select_db("Nice try", $resDB);

function createKey()
{
    //create a random key
    $strKey = md5(microtime());

    //check to make sure this key isnt already in use
    $resCheck = mysql_query("SELECT count(*) FROM downloads WHERE downloadkey = '{$strKey}' LIMIT 1");
    $arrCheck = mysql_fetch_assoc($resCheck);
    if ($arrCheck['count(*)']){
        //key already in use
        return createKey();
    } else {
        //key is OK
        return $strKey;
    }
}

//get a unique download key
$strKey = createKey();

//insert the download record into the database
mysql_query("INSERT INTO downloads (downloadkey, file, expires) VALUES ('{$strKey}', 'fernanfloo-OMG.zip', '".(time()+(60*60*24*7))."')");

?>

<html>
<head>
<title>Descargar Fernanfloo OMG sonido</title>
</head>
<h1>By Skyleter</h1>
<p>Su link de descarga es:</p>
<strong><a href="download.php?key=<?=$strKey;?>">download.php?key=<?=$strKey;?></a></strong>
<p>Link caduca en 7 días..</p>
</html>

PS: header worked but as i said, i want to show the unique download link, and ONLY IF THE USER REFRESH PAGE, redirect. (and everytime redirect to a page)

Haider Ali · Accepted Answer · 2016-01-10 04:14:41Z

1

<?php
    //Get client ip.

    $ip = "203.146.92.56";

    $d = file_get_contents("ips.txt");
    $d = explode(",",$d);

    if(in_array($ip,$d))
    {
        echo "Only one download per ip";
    }
    else
    {
        //display download link
        fwrite(fopen('ips.txt','a'),$ip.",");
    }

ip.txt would look like this

203.146.92.56,117.56.34.21,

Note that, this just a basic way of doing what you need. You could tweak this a lot. Say, individual files for individual users so you can clear logs for X ip every X period of time and so on. Maybe even different logs for different files.

answered Jan 10, 2016 at 4:14

Haider Ali

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2 Comments

Skyleter Over a year ago

Oh thanks! I will try it tomorrow :D, also, in $ip = "203.146.92.56"; , 203.146.92.56 < is an example no? I need to replace that ip with anything else or leave it blank?

Haider Ali Over a year ago

That's an example, you will need to replace it with the user's ip address.

Bruce Staples · Accepted Answer · 2016-01-10 03:22:48Z

0

I think you need to investigate controlling sessions for your connecting clients. The session parameter will be able to be used to prevent new keys being generated.

answered Jan 10, 2016 at 3:22

Bruce Staples

413 bronze badges

2 Comments

user5051310 Over a year ago

a session would work... unless he's worried about the user closing the browser, reopening it, and then coming back for another download.

Bruce Staples Over a year ago

In which case he will need to do something more persistent ... like cookies.

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