URL shorteners (such as bit.ly and tinyurl) have been called the "herpes of the web". Beyond just link-rot, a public shortening service is per se an open redirect vulnerability. Their ubiquity makes them an easy vector for spammers, phishers, and cross-site forgery attacks.
Joshua Schachter writes:
With a shortening service, you're adding something that acts like a third DNS resolver, except one that is assembled out of unvetted PHP and MySQL, without the benevolent oversight of luminaries like Dan Kaminsky and St. Postel.
Luckily, you don't have to contribute to this scourge.
Drupal 7 has adopted the shortlink microformat, which adds a <head> element like so:
<link rel="shortlink" href="http://www.example.com/node/1" />
When we rebuilt our site in D7, we decided to ditch bit.ly in favor of these built-in shortlinks. However, I also felt the /node/ piece of the path was superfluous, and even strange-looking to visitors outside the Drupal community.
So, we decided to shorten them even further, removing both the "www" and /node/ from the URL. This required only a few minor changes:
.htaccess
Care was taken not to add the "www" prefix for these shortlinks, because doing so would result in multiple redirects (which still works, but is inefficient).
# Redirect all paths to the "www" prefix, except for /NNNN
RewriteCond %{HTTP_HOST} ^metaltoad\.com$ [NC]
RewriteCond %{REQUEST_URI} !^/\d+$
RewriteCond %{REQUEST_URI} !^/index.php
RewriteCond %{REQUEST_URI} !^/node/\d+
RewriteRule ^(.*)$ http://www.metaltoad.com/$1 [L,R=301]
# Allow short URLs of the form metaltoad.com/123
RewriteCond %{REQUEST_URI} ^/\d+$
RewriteRule ^(.*)$ index.php?q=node/$1 [L,QSA]
Redirect node/NNN to the alias
The next piece was to redirect to the actual path alias. At the time this site was built, neither the Global Redirect module nor it's successor Redirect, were deemed production-ready, so we rolled our own interim solution:
/**
* Implements hook_init().
*/
function mymodule_init() {
// Redirect node/NNN to the path alias, if available.
// The globalredirect module isn't currently available for D7.
if (preg_match('/^node\/\d+$/', request_path())) {
$alias = drupal_get_path_alias();
if ($alias != request_path()) {
// Setting the redirect headers manually allows them to be
// cached, which drupal_goto does not.
drupal_add_http_header('Location', url($alias,
array('absolute' => TRUE)));
drupal_add_http_header('Status', '301 Moved Permanently');
print '301 Moved Permanently';
drupal_page_footer();
exit();
}
}
}
Altering the <head> in template.php
This code was added to template.php to alter the <head> element. Since this is a renderable array in D7 it's easy!
/**
* Implements hook_html_head_alter().
* Generates shorter shortlinks of the form metaltoad.com/NNN.
*/
function metaltoad_html_head_alter(&$head_elements) {
foreach ($head_elements as $key => $element) {
if (isset($element['#attributes']['rel']) &&
$element['#attributes']['rel'] == 'shortlink') {
$href =& $head_elements[$key]['#attributes']['href'];
if (preg_match('/^\/node\/\d+$/', $href)) {
$href = str_replace('/node/', '', $href);
$href = "http://metaltoad.com/$href";
}
}
}
}
$base_url
Lastly, we made sure to explicitly set $base_url in settings.php. This ensures that when the Location header set, it uses the correct domain including the "www", again avoiding inefficient multiple redirects.
$base_url = 'http://www.metaltoad.com';
Now, we have our own share-friendly links that are only a few characters longer than bit.ly!
Before: http://bit.ly/c9Vk1R
After: http://metaltoad.com/318