guests/windows: detect the port for RDP

plugins/guests/windows/cap/rdp.rb

@@ -9,8 +9,33 @@ module VagrantPlugins
             username = machine.config.winrm.username
           end
 
+          host = ssh_info[:host]
+          port = 3389
+
+          if host == "127.0.0.1"
+            # We need to find a forwarded port...
+            search_port = 3389
+            ports       = nil
+            if machine.provider.capability?(:forwarded_ports)
+              ports = machine.provider.capability(:forwarded_ports)
+            else
+              ports = {}.tap do |result|
+                machine.config.vm.networks.each do |type, netopts|
+                  next if type != :forwarded_port
+                  next if !netopts[:host]
+                  result[netopts[:host]] = netopts[:guest]
+                end
+              end
+            end
+
+            ports = ports.invert
+            port  = ports[search_port]
+            return nil if !port
+          end
+
           return {
-            host: machine.provider.capability(:public_address),
+            host: host,
+            port: port,
             username: username,
           }
         end

plugins/hosts/windows/cap/rdp.rb

@@ -11,6 +11,7 @@ module VagrantPlugins
           opts   = {
             "drivestoredirect:s"       => "*",
             "full address:s"           => rdp_info[:host],
+            "port:i"                   => rdp_info[:port],
             "prompt for credentials:i" => "1",
             "username:s"               => rdp_info[:username],
           }