Question

I have 5 domains which are re-directed to a single hosting. I am using Joomla on the website having an issue with banner. I want that if someone redirected from domain1 the hosting site shows banner for domain1, domain2 banner2 and so on.

What would be the best methodology whether in Joomla or Core PHP?

Answer 1

You need to use 'HTTP_REFERER' in PHP’s $_SERVER superglobal. Read the manual for more information.

Basically, HTTP_REFERER contains the URI of the site that was directed to your host. It’s not guaranteed to actually contain a value, but it’s your best bet without involving GET variables issued in the URL. Note: you will have to parse out the domain name before you can use it.

The manual has this to say…

The address of the page (if any) which referred the user agent to the
current page. This is set by the user agent. Not all user agents will
set this, and some provide the ability to modify HTTP_REFERER as a
feature. In short, it cannot really be trusted.

Your code might look like this…

function GetBannerForDomain() {
    $url_array = parse_url($_SERVER['HTTP_REFERER']);
    switch (str_replace("www.", "", $url_array['host')) {
        case 'example.com':
            $img_src = 'path/to/banner.png';
        default:
            $img_src = 'path/to/default/banner.png';
    }

    return $img_src;
}

If you have any control over the re-directing domains, you could fall back to using GET vars in the redirect, like so…

http://www.yoursite.com/referer/site1.com