Check if a domain name is valid

php/func.php

@@ -0,0 +1,10 @@
+<?php
+
+function is_valid_domain_name($domain_name)
+{
+    return (preg_match("/^([a-z\d](-*[a-z\d])*)(\.([a-z\d](-*[a-z\d])*))*$/i", $domain_name) &&  //valid chars check
+        preg_match("/^.{1,253}$/", $domain_name) && //overall length check
+        preg_match("/^[^\.]{1,63}(\.[^\.]{1,63})*$/", $domain_name)); //length of each label
+}
+
+?>