Magento Base URL Redirect

Magento’s configuration includes a hard coded field for the base site URL. This often creates headaches when a user migrates a system to a new server/URL, but hasn’t updated the URL entries in the core_config_data table. These headaches are compounded by

1. The fact that the entries in core_config_data are cached by Magento
2. Most web browsers aggressively cache HTTP header based redirects
3. If a user didn’t update core_config_data, there’s also a good chance they’re the sort of user who wouldn’t update their web server configuration

Whenever I’m facing a problem like this with a system, I like to hop to the following code point

#File: app/code/core/Mage/Core/Controller/Varien/Front.php
    if (isset($uri['scheme']) && $uri['scheme'] != $request->getScheme()
        || isset($uri['host']) && $uri['host'] != $request->getHttpHost()
        || isset($uri['path']) && strpos($requestUri, $uri['path']) === false
    ) {            
        Mage::app()->getFrontController()->getResponse()
            ->setRedirect($baseUrl, $redirectCode)
            ->sendResponse();
        exit;
    }

This complicated conditional statement is where Magento performs a redirect if the request URL doesn’t match the base url. Some quick var_dump/exit debugging before the call to sendResponse can be a nice sanity check.