PHP Get HTTP Request Headers - get_headers()

I was doing some tests to make a simple web crawler in PHP and I want to share with you get_headers() function.

<?php  
function get_http_response_code($headers) {  
  return intval(substr($headers[0], 9, 3));
}
$url = 'http://tig.pt';
$headers = get_headers($url, 1);
if ($headers){  
    var_dump(get_http_response_code($headers));
    var_dump($headers['Location']);
    var_dump($headers);
} else {
    echo 'Error loading header - failed to open stream';
}
?>

With this simple example, we can test the get_headers() function and extract some information from it.

Since my blog has a http to https redirect, this will get us a 301 Moved Permanently redirect and we can extract the new Location directly from $headers variable, that will be https://tig.pt.

Sadly I didn't find any direct way to get the response code without making a new request, and a new request could give a different response from the first one, but we can create a simple get_http_response_code function that parses it from the string with intval(substr($headers[0], 9, 3)) getting the 3 numbers code that starts at character 9, and convert it to int for simple handling.

I also added a simple if ($headers) because if theres any error in the request, no response at all, or url doesn't exist, the function returns NULL.

This can be used to handle any kind of content and it's a simple way to test an up status, or content modified date if you are doing cache control.

I will use it to feed my crawler with information about broken links.

You can run this example on terminal with:
curl https://static.tig.pt/php/get_headers.php

Don't forget to use <pre> html tags on your vardumps to easily read on the browser.

If you prefer other way to do it, or want to share your work, just contact me.

Tiago Rodrigues

Dipping into programming one toe at a time. Twitter: @TigPT | Email: [email protected]

Lisbon, Portugal

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