The function "short_url" is used in several addons, so it deserves a central place.

include/network.php

@@ -1173,3 +1173,27 @@ function original_url($url, $depth=1, $fetchbody = false) {
 
         return($url);
 }
+
+if (!function_exists('short_link')) {
+function short_link($url) {
+	require_once('library/slinky.php');
+	$slinky = new Slinky($url);
+	$yourls_url = get_config('yourls','url1');
+	if ($yourls_url) {
+		$yourls_username = get_config('yourls','username1');
+		$yourls_password = get_config('yourls', 'password1');
+		$yourls_ssl = get_config('yourls', 'ssl1');
+		$yourls = new Slinky_YourLS();
+		$yourls->set('username', $yourls_username);
+		$yourls->set('password', $yourls_password);
+		$yourls->set('ssl', $yourls_ssl);
+		$yourls->set('yourls-url', $yourls_url);
+		$slinky->set_cascade( array($yourls, new Slinky_UR1ca(), new Slinky_Trim(), new Slinky_IsGd(), new Slinky_TinyURL()));
+	} else {
+		// setup a cascade of shortening services
+		// try to get a short link from these services
+		// in the order ur1.ca, trim, id.gd, tinyurl
+		$slinky->set_cascade(array(new Slinky_UR1ca(), new Slinky_Trim(), new Slinky_IsGd(), new Slinky_TinyURL()));
+	}
+	return $slinky->short();
+}};