updated the url regexp

shorty.rb

@@ -15,11 +15,23 @@
 class Url
   include DataMapper::Resource
 
+  IPv4_PART = /\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5]/  # 0-255
+  URL_REGEXP = %r{
+    \A
+    https?://                                        # http:// or https://
+    ([^\s:@]+:[^\s:@]*@)?                            # optional username:pw@
+    ( (xn--)?[^\W_]+([-.][^\W_]+)*\.[a-z]{2,6}\.? |  # domain (including Punycode/IDN)...
+        #{IPv4_PART}(\.#{IPv4_PART}){3} )            # or IPv4
+    (:\d{1,5})?                                      # optional port
+    ([/?]\S*)?                                       # optional /whatever or ?whatever
+    \Z
+  }iux
+
   property :url, String, :length => 2024 # 2 kilobytes, thats one BIG url! Bigger than what IE can handle!
   property :key, String, :index => true, :key => true, :length => 64
 
   validates_present :url
-  validates_format :url, :as => :url
+  validates_format :url, :as => URL_REGEXP
   validates_is_unique :key
   validates_format :key, :as => /^[-_a-z0-9]+$/i  # I only want to allow alpha, nums, _, and - in the URL key
 end