Why Doesn't This PHP Download Script Work? - php

Question

Here is a simple script I have written to limit downloads for users to one at a time (IE if they are downloading a file then they cannot download another one until they cancel the current download or it finishes).
ignore_user_abort(true);
$local_file = $_GET['filename'];
$download_file = explode("/", $local_file);
$download_file = $download_file[count($download_file) -1];
// set the download rate limit (value is in kilobytes per second
$download_rate = 100;
if(file_exists($local_file) && is_file($local_file)) {
$ip = visitor_ip();
if(!are_downloading($ip)) {
header('Cache-control: private');
header('Content-Type: application/octet-stream');
header('Content-Length: '.filesize($local_file));
header('Content-Disposition: filename='.$download_file);
flush();
$file = fopen($local_file, "r");
log_downloader($ip);
while(!feof($file)) {
if (!connection_aborted()) {
// send the current file part to the browser
print fread($file, round($download_rate * 1024));
// flush the content to the browser
flush();
// sleep one second
sleep(1);
} else {
break;
}
}
clear_downloader($ip);
fclose($file);
} else {
die('<span style="color:#DDDDDD">Due to server limitations you may only download one file at a time. Please cancel or wait for your current download to finish before trying again. Click here to return.</span>');
}
} else {
die('Error: The file '.$local_file.' does not exist!');
}
function visitor_ip() {
if(isset($_SERVER['HTTP_X_FORWARDED_FOR']))
$TheIp=$_SERVER['HTTP_X_FORWARDED_FOR'];
else $TheIp=$_SERVER['REMOTE_ADDR'];
return trim($TheIp);
}
function are_downloading($ip) {
$query = "select * from downloaders where ip_addr='$ip'";
$result = mysql_query($query);
$num_rows = mysql_num_rows($result);
return $num_rows > 0;
}
function log_downloader($ip) {
$query = "insert into downloaders (ip_addr) values ('$ip')";
$result = mysql_query($query);
}
function clear_downloader($ip) {
$query = "delete from downloaders where ip_addr='$ip'";
$result = mysql_query($query);
}
When I test it out, it works fine, but for a lot of people, their IP never gets cleared out of the database - even when they have finished downloading/cancelled a file. Why don't the IPs get deleted?

Answer 1

The problem was that with big downloads the MySQL connection went away, I simply had to reconnect in the clear_downloader function and now it works fine.