1 files changed, 8 insertions, 4 deletions
diff --git a/lib/puppet/parser/functions/is_domain_name.rb b/lib/puppet/parser/functions/is_domain_name.rb
index b3fee96..90ede32 100644
--- a/lib/puppet/parser/functions/is_domain_name.rb
+++ b/lib/puppet/parser/functions/is_domain_name.rb
@@ -13,16 +13,16 @@ Returns true if the string passed to this function is a syntactically correct do
         "given #{arguments.size} for 1")
     end
 
-    domain = arguments[0]
+    # Only allow string types
+    return false unless arguments[0].is_a?(String)
+
+    domain = arguments[0].dup
 
     # Limits (rfc1035, 3.1)
     domain_max_length=255
     label_min_length=1
     label_max_length=63
 
-    # Only allow string types
-    return false unless domain.is_a?(String)
-
     # Allow ".", it is the top level domain
     return true if domain == '.'
 
@@ -33,6 +33,10 @@ Returns true if the string passed to this function is a syntactically correct do
     return false if domain.empty?
     return false if domain.length > domain_max_length
 
+    # The top level domain must be alphabetic if there are multiple labels.
+    # See rfc1123, 2.1
+    return false if domain.include? '.' and not /\.[A-Za-z]+$/.match(domain)
+
     # Check each label in the domain
     labels = domain.split('.')
     vlabels = labels.each do |label|