Extra common engine and fix default encoding

MSP-9653

Extra config and initializers that can we shared between
Metasploit::Framework::Application and the future
Metasploit::Framework::Engine.  Move the default encoding setup from
lib/msf/sanity.rb to a before_initialize callback for the shared config
so that gems, like gherkin that depend on the utf-8 default internal
encoding can be loaded.

config/application.rb

@@ -26,11 +26,18 @@ Bundler.require(
     )
 )
 
+#
+# Project
+#
+
+require 'metasploit/framework/common_engine'
 require 'msf/base/config'
 
 module Metasploit
   module Framework
     class Application < Rails::Application
+      include Metasploit::Framework::CommonEngine
+
       user_config_root = Pathname.new(Msf::Config.get_config_root)
       user_database_yaml = user_config_root.join('database.yml')
 

lib/metasploit/framework/common_engine.rb

@@ -0,0 +1,73 @@
+#
+# Standard Library
+#
+
+require 'fileutils'
+
+# `Rails::Engine` behavior common to both {Metasploit::Framework::Application} and {Metasploit::Framework::Engine}.
+module Metasploit::Framework::CommonEngine
+  extend ActiveSupport::Concern
+
+  included do
+    #
+    # config
+    #
+
+    # Force binary encoding to remove necessity to set external and internal encoding when construct Strings from
+    # from files.  Socket#read always returns a String in ASCII-8bit encoding
+    #
+    # @see http://rubydoc.info/stdlib/core/IO:read
+    config.before_initialize do
+      encoding = 'binary'
+      Encoding.default_external = encoding
+      Encoding.default_internal = encoding
+    end
+
+    config.paths.add 'data/meterpreter', glob: '**/ext_*'
+    config.paths.add 'modules'
+
+    #
+    # `initializer`s
+    #
+
+    initializer 'metasploit_framework.merge_meterpreter_extensions' do
+      Rails.application.railties.engines.each do |engine|
+        merge_meterpreter_extensions(engine)
+      end
+
+      # The Rails.application itself could have paths['data/meterpreter'], but will not be part of
+      # Rails.application.railties.engines because only direct subclasses of `Rails::Engine` are returned.
+      merge_meterpreter_extensions(Rails.application)
+    end
+  end
+
+  #
+  # Instance Methods
+  #
+
+  private
+
+  # Merges the meterpreter extensions from `engine`'s `paths['data/meterpreter]`.
+  #
+  # @param engine [Rails::Engine] a Rails engine or application that has meterpreter extensions
+  # @return [void]
+  # @todo Make metasploit-framework look for meterpreter extension in paths['data/meterpreter'] from the engine instead of copying them.
+  def merge_meterpreter_extensions(engine)
+    data_meterpreter_paths = engine.paths['data/meterpreter']
+
+    # may be `nil` since 'data/meterpreter' is not part of the core Rails::Engine paths set.
+    if data_meterpreter_paths
+      source_paths = data_meterpreter_paths.existent
+      destination_directory = root.join('data', 'meterpreter').to_path
+
+      source_paths.each do |source_path|
+        basename = File.basename(source_path)
+        destination_path = File.join(destination_directory, basename)
+
+        unless destination_path == source_path
+          FileUtils.copy(source_path, destination_directory)
+        end
+      end
+    end
+  end
+end

lib/msf/sanity.rb

@@ -33,18 +33,6 @@ if (RUBY_VERSION =~ /^1\.9\.1/)
   $stderr.puts "*** Ruby 1.9.1 is not supported, please upgrade to Ruby 1.9.3 or newer."
 end
 
-if(RUBY_VERSION =~ /^(1\.9|2\.0)\./)
-  # Load rubygems before changing default_internal, otherwise we may get
-  # Encoding::UndefinedConversionError as the gemspec files are loaded
-  require 'rubygems'
-  Gem::Version # trigger Rubygems to fully load
-
-  # Force binary encoding for Ruby versions that support it
-  if(Object.const_defined?('Encoding') and Encoding.respond_to?('default_external='))
-    Encoding.default_external = Encoding.default_internal = "binary"
-  end
-end
-
 if(RUBY_PLATFORM == 'java')
   require 'socket'
   s = Socket.new(::Socket::AF_INET, ::Socket::SOCK_STREAM, ::Socket::IPPROTO_TCP)