How to check if the URL is iframe embeddable in PHP?

Question

Some websites are not allowed to be embedded via iframe. They produce the following error:

Refused to display 'https://news.ycombinator.com/news' in a frame because it 
set 'X-Frame-Options' to 'DENY'. 

Our app allows URL submissions from users. We want to check on the server side if the website could be embedded in iframe and add a corresponding flag. On the client we check for the flag, and either do iframe embed or just provide a direct link to a webpage.

How do I check whether website will support iframe or not?

Answer 1

X-Frame-Options is a response header sent by the server, so have your server perform an HTTP GET on the URL you'd like to test, see if the X-Frame-Options header is present, and if it is... judging by the spec you're not likely to be allowed to embed it at all.

Answer 2

Try this code:

$url = "http://www.google.com/";
$url_headers = get_headers($url);
foreach ($url_headers as $key => $value)
{
    $x_frame_options_deny = strpos(strtolower($url_headers[$key]), strtolower('X-Frame-Options: DENY'));
    $x_frame_options_sameorigin = strpos(strtolower($url_headers[$key]), strtolower('X-Frame-Options: SAMEORIGIN'));
    $x_frame_options_allow_from = strpos(strtolower($url_headers[$key]), strtolower('X-Frame-Options: ALLOW-FROM'));
    if ($x_frame_options_deny !== false || $x_frame_options_sameorigin !== false || $x_frame_options_allow_from !== false)
    {
        echo 'url prevent iframe!';
    }
}

Answer 3

I wrote this function:

function allowEmbed($url) {
    $header = @get_headers($url, 1);

    // URL okay?
    if (!$header || stripos($header[0], '200 ok') === false) return false;

    // Check X-Frame-Option
    elseif (isset($header['X-Frame-Options']) && (stripos($header['X-Frame-Options'], 'SAMEORIGIN') !== false || stripos($header['X-Frame-Options'], 'deny') !== false)) {
        return false;
    }

    // Everything passed? Return true!
    return true;
}