Accurate Redirects Tester
A web page redirect sends a browser or robot/spider to a destination different than the original requested URL.
Reasons for redirecting a URL are numerous. Generally, reasons are related to pages having been moved or the browser being routed through a script such as a click counter.
If a redirect that used to be reliable no longer works or redirects to the wrong place, it needs to be investigated. Similarly, if an unexpected redirect suddenly starts to happen. Those situations may be caused by a bug inadvertently introduced into a script, a new WordPress theme, the server being hacked, or any of a number of other reasons.
When investigating with your browser, it may give you wrong answers. The browser may be using cache, for example. Or it may be logged into a dashboard, WordPress for example, that bypasses the redirect. (A friend had that happen a few days before the writing of this article.)
Those are reasons why the PHP software Accurate Redirects Tester was built.
It has no cache. It uses no cookies. The redirects it reports are actual live redirects at the moment Accurate Redirects Tester was employed.
Accurate Redirects Tester detects redirects via .htaccess files and redirects via PHP and other server-side software that specify new URL locations in the header (the response the server sends before it sends the web page itself). It does not detect HTML meta redirects or JavaScript redirects.
Here is the source code for Accurate Redirects Tester.
<?php
/*
Accurate Redirects Tester
Version 1.0
May 19, 2023
Will Bontrager Software LLC
https://www.willmaster.com/
*/
echo <<<PAGETOP
<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="content-type" content="text/html;charset=utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Accurate Redirects Tester</title>
<style type="text/css">
* { box-sizing:border-box; }
html, body { font-size:100%; font-family:sans-serif; }
.pre { font-family:monospace; font-size:120%; border:1px solid #ccc; border-radius;.5em; padding:.5em; overflow:auto; white-space:pre; margin-top:0; }
.above-pre { margin-bottom:.2em; }
a { text-decoration:none; }
input { width:100%; font-size:1em; }
#content { position:relative; max-width:500px; margin:.25in auto; background-color:transparent; }
</style>
</head>
<body><div id="content">
<div style="position:absolute; right:0; top:0;">
<a href="https://www.willmaster.com/">
<img src="https://www.willmaster.com/images/wmlogo_icon.gif" style="border:none; outline:none; width:50px; height:50px;" alt="Willmaster.com logo">
</a>
</div>
<h1 style="margin-top:0; margin-right:60px;">Accurate Redirects Tester</h1>
PAGETOP;
if( isset($_POST['url']) and strlen($_POST['url']) ) { ListRedirectURLs(); }
else { $_POST['url'] = ''; }
echo <<<PAGEBOTTOM
<p>Follow redirects to a URL's final destination.</p>
<form method="post" enctype="multipart/form-data" action="{$_SERVER['PHP_SELF']}">
<p>The URL to follow:<br><input type="text" name="url" value="{$_POST['url']}"></p>
<p><input type="submit"></p>
</form>
</div></body></html>
PAGEBOTTOM;
exit;
$redirectCount = 0;
function ListRedirectURLs()
{
global $redirectCount;
echo '<p class="above-pre">Test results:</p><p class="pre">';
echo "Requested URL: <a href='{$_POST['url']}'>{$_POST['url']}</a>\n";
$info = GetPageHeader($_POST['url']);
while( isset($info['redirect_url']) and strlen($info['redirect_url']) )
{
echo " Redirect {$info['http_code']}: {$info['redirect_url']}\n";
$info = GetPageHeader($info['redirect_url']);
$redirectCount++;
if( $redirectCount > 25 )
{
echo "(Abandoning process; too many redirects.)\n";
return;
}
}
$link = "<a href='{$info['url']}'>{$info['url']}</a>";
if( $info['http_code'] < 100 ) { $info['http_code'] = ' 0'; $link = '(not available)'; }
$final = $info['http_code']=='200' ? 'Final URL 200' : " Error {$info['http_code']}";
echo "$final: $link";
echo '</p><hr style="margin:.25in 0; border:1px dashed black; border-bottom:none;">';
} # function ListRedirectURLs()
function GetPageHeader($url)
{
$options = array(
CURLOPT_RETURNTRANSFER => true,
CURLOPT_HEADER => true,
CURLOPT_CONNECTTIMEOUT => 10,
CURLOPT_TIMEOUT => 20,
CURLOPT_USERAGENT => $_SERVER['HTTP_USER_AGENT'],
);
$ch = curl_init($url);
curl_setopt_array($ch,$options);
curl_exec($ch);
$info = curl_getinfo($ch);
curl_close($ch);
return $info;
} # function GetPageHeader()
?>
No customization needs to be done. Simply save the above source code as URLtester.php or other *.php file name, and then upload it to your server.
To use the software, type the URL of URLtester.php into your browser's address bar.
Here is a live example.
Accurate Redirects Tester
Follow redirects to a URL's final destination.
The URL to follow:
If you suspect your browser may be caching a redirect that you are testing, use Accurate Redirects Tester to bypass the cache. It reports exactly what would be encountered by a browser or robot that accessed the URL for the first time at that moment.
The two most frequent redirect responses you'll see when you use the software is 301 and 302. Code 301 tells the browser that the redirect is permanent, to go directly to the final destination whenever the redirect URL is requested in the future. Code 302 tells the browser the the redirect is temporary, to always check the redirect again whenever it is requested in the future (because it might no longer be a redirect).
Accurate Redirects Tester can also be used to test known redirect URLs and reveal the redirect sequence. Email links, for example. Or links to known redirecting services.
(This content first appeared in Possibilities newsletter.)
Will Bontrager
