update the one-time link on the page

Question

I have a one-time link like in this:

<?php
    session_start();
    $file1 = "img/img1.jpeg";
    $key1 = md5($file1 . microtime());
    $_SESSION[$key1] = $file1;
    $link1 = "download.php?key=" . $key1;
    echo "<a href='" . $link1 . "'id='button1'>download</a><br>";

?>

download.php

<?php
session_start();
// Get the key from the query string
$key = $_GET['key'];
// Check if the key exists in the session
if(isset($_SESSION[$key])) {
  $file = $_SESSION[$key];
  // Remove the key from the session to prevent reuse
  unset($_SESSION[$key]);
  // Set the content type and headers for the file
  header("Content-Type: application/octet-stream");
  header("Content-Disposition: attachment; filename=" . basename($file));
  header("Content-Length: " . filesize($file));
  readfile($file);
  
}
else{
   echo("Invalid link");
}
?>

Every time the page is refreshed, it creates a new one-time link that can only be used once.

And if I follow this link, the file will be downloaded. But when I follow it a second time, the link is no longer valid. How can I make the link update when clicking on it (without refreshing the page), so that the link is always valid?

I do not know how to do it? How can this be done? Via ajax? Or how?

What is the point to make a one time download like that can be used more than once? — mplungjan, Feb 17 '23 at 09:50
Why did you tag this with Javascript and HTML? Is there any such code involved? Then please share it — Nico Haase, Feb 17 '23 at 09:52
Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. — Community, Feb 17 '23 at 09:53
@mplungjan No, the link should change on every click without refresh page. — name, Feb 17 '23 at 09:53
[Ajax could be used to get the url](https://stackoverflow.com/questions/4545311/download-a-file-by-jquery-ajax), create the link and then click it. Hundreds of examples exist — mplungjan, Feb 17 '23 at 10:03
@AbbasBagheri why would that make any difference? PHP is PHP, no matter how it was installed. — ADyson, Feb 17 '23 at 10:43
In my experience, sometomes sessions do not working correctly on xampp. — Abbas Bagheri, Feb 17 '23 at 10:46

score 0 · Answer 1 · answered Feb 17 '23 at 11:07

Here you go:

<?php
    session_start();
    $file1 = "img/img1.jpeg";
    $key1 = md5($file1 . microtime());
    $_SESSION[$key1] = $file1;
    $link1 = "download.php?key=" . $key1;
    echo "<a href='" . $link1 . "'id='button1'>download</a><br>";

?>

download.php

<?php
session_start();
// Get the key from the query string
$key = $_GET['key'];
// Check if the key exists in the session
if(isset($_SESSION[$key])) {
  $file = $_SESSION[$key];
  // DO NOT remove the key from the session, to allow reuse
  //unset($_SESSION[$key]);
  // Set the content type and headers for the file
  header("Content-Type: application/octet-stream");
  header("Content-Disposition: attachment; filename=" . basename($file));
  header("Content-Length: " . filesize($file));
  readfile($file);
  
}
else{
   echo("Invalid link");
}
?>

It works now. :-)

(This answers your question, but if it's not what you wanted, you might need to be clearer about your objective and reasons.)

It *already* can only be used once with the code you have now. That was the whole point of what you wrote. — Michael G, Feb 17 '23 at 21:06

update the one-time link on the page

1 Answers1