Make some methods not dependant of the instance flavor

lib/msf/core/exploit/cmdstager.rb

@@ -172,7 +172,7 @@ module Exploit::CmdStager
     raise ArgumentError, "Unable to select CMD Stager" if flavor.nil?
     raise ArgumentError, "The CMD Stager selected isn't compatible with the target" unless compatible?(flavor)
     self.decoder = select_decoder(opts)
-    raise ArgumentError, "Unable to select decoder stub" if decoder.nil? && decoder_required?
+    raise ArgumentError, "Unable to select decoder stub" if decoder.nil? && decoder_required?(flavor)
   end
 
 
@@ -195,21 +195,23 @@ module Exploit::CmdStager
     STAGERS[flavor][:klass].new(exe)
   end
 
-  # Returns the default decoder stub for the current cmd stager flavor.
+  # Returns the default decoder stub for the input flavor.
   #
+  # @param f [Symbol] the input flavor.
   # @return [Symbol] the decoder.
   # @return [nil] if there isn't a default decoder to use for the current
   #   cmd stager flavor.
-  def default_decoder
-    DECODERS[flavor]
+  def default_decoder(f)
+    DECODERS[f]
   end
 
-  # Returns the better cmd stager decoder stub to use for the current flavor.
+  # Returns the better cmd stager decoder stub to use for the input flavor.
   #
+  # @param f [Symbol] the input flavor.
   # @return [Symbol] the decoder to use.
   # @return [nil] if there isn't a best decoder to use for the current flavor.
-  def decoder_required?
-    STAGERS[flavor][:decoder]
+  def decoder_required?(f)
+    STAGERS[f][:decoder]
   end
 
   # Selects the correct cmd stager decoder to use based on three rules: (1) use
@@ -225,7 +227,7 @@ module Exploit::CmdStager
   def select_decoder(opts)
     return opts[:decoder].to_sym if opts.include?(:decoder)
     return datastore['CMDSTAGER::DECODER'].to_sym unless datastore['CMDSTAGER::DECODER'].blank?
-    default_decoder
+    default_decoder(flavor)
   end
 
   # Selects the correct cmd stager to use based on three rules: (1) use the