A script to allow only a certain amount of users on a webpage?

[jacksont123]

Can anyone please show me a php script that only allows 300 users on a page at once, but makes the 301st user and so on be redirected to another page?

[Twey]

Since HTTP is stateless, it's impossible to do this. The best you can do is only allow the page to be requested 300 times every, say, five minutes.

[jacksont123]

To rephrase my first post, I kinda want a function like the one in FTP that only allows the first x users, then blocks the rest until one of the first x users leaves.
If I can't do what I meant in the first post, how would I be able to do what you suggested?

[Twey]

Store a list of last-seen times in a database. Each time somebody accesses the page:

• Check if there are more than 300 times in the database
• If so, redirect the user
• Otherwise:
  • Add the current time to the database
  • Remove any times more than five minutes ago from the database
  • Serve the page

[boxxertrumps]

logical error in there twey.

once you have 300 people, noone can get in, and the database isnt checked for timeouts.
This:
Remove any times more than five minutes ago from the database
Should be first.

[Twey]

Ah! You're right.

• Remove any times more than five minutes ago from the database
• Check if there are more than 300 times in the database
• If so, redirect the user
• Otherwise:
  • Add the current time to the database
  • Serve the page

[boxxertrumps]

<?php
$contents = @file_get_contents("includes/online.txt");
$array = explode("\r\n",$contents);
$curr = time();
foreach($array){
  $dif = $curr-$array;
  if($dif >= "300") {
  unset($array);
  }
};
$num = count($array);
if($num >= "299") {
  $array[] = $curr;
?>

WEB PAGE GOES HERE

<?php } else { ?>

Alternate web page/meta redirects

<?php
};
$towrite = implode("\r\n",$array);
$handle = fopen("includes/online.txt","w+");
fwrite($handle,$towrite);
fclose($handle);
?>

untested. flatfile DB. 300 requests every 5 min(300 sec.)

[Twey]

$contents = @file_get_contents("includes/online.txt"); 
$array = explode("\r\n",$contents);

Rather, $arr = file('includes/online.txt'); The former will break on UNIX-based servers, which use \n rather than \r\n to signify a linebreak.