Extract option require pattern to helper Module

MSP-10905

`Metasplot::Framework::Require.optionally` can be used to optionally
require a library and then issue a warning if the require fails or run a
block when it succeeds.

Author: limhoff-r7

lib/metasploit/framework/command/base.rb

@@ -10,6 +10,7 @@
 
 require 'metasploit/framework/command'
 require 'metasploit/framework/parsed_options'
+require 'metasploit/framework/require'
 
 # Based on pattern used for lib/rails/commands in the railties gem.
 class Metasploit::Framework::Command::Base
@@ -55,16 +56,7 @@ def self.require_environment!
 
     # support disabling the database
     unless parsed_options.options.database.disable
-      begin
-        require 'active_record/railtie'
-      rescue LoadError
-        warn "activerecord not in the bundle, so database support will be disabled."
-        warn "Bundle installed '--without #{Bundler.settings.without.join(' ')}'"
-        warn "To clear the without option do `bundle install --without ''` " \
-             "(the --without flag with an empty string) or " \
-             "`rm -rf .bundle` to remove the .bundle/config manually and " \
-             "then `bundle install`"
-      end
+      Metasploit::Framework::Require.optionally_active_record_railtie
     end
 
     Rails.application.require_environment!

lib/metasploit/framework/require.rb

@@ -0,0 +1,92 @@
+# @note needs to use explicit nesting. so this file can be loaded directly without loading 'metasploit/framework', this
+#   file can be used prior to Bundler.require.
+module Metasploit
+  module Framework
+    # Extension to `Kernel#require` behavior.
+    module Require
+      #
+      # Module Methods
+      #
+
+      # Tries to require `name`.  If a `LoadError` occurs, then `without_warning` is printed to standard error using
+      # `Kernel#warn`, along with instructions for reinstalling the bundle.  If a `LoadError` does not occur, then
+      # `with_block` is called.
+      #
+      # @param name [String] the name of the library to `Kernel#require`.
+      # @param without_warning [String] warning to print if `name` cannot be required.
+      # @yield block to run when `name` requires successfully
+      # @yieldreturn [void]
+      # @return [void]
+      def self.optionally(name, without_warning)
+        begin
+          require name
+        rescue LoadError
+          warn without_warning
+          warn "Bundle installed '--without #{Bundler.settings.without.join(' ')}'"
+          warn "To clear the without option do `bundle install --without ''` " \
+           "(the --without flag with an empty string) or " \
+           "`rm -rf .bundle` to remove the .bundle/config manually and " \
+           "then `bundle install`"
+        else
+          if block_given?
+            yield
+          end
+        end
+      end
+
+      # Tries to `require 'active_record/railtie'` to define the activerecord Rails initializers and rake tasks.
+      #
+      # @example Optionally requiring 'active_record/railtie'
+      #   require 'metasploit/framework/require'
+      #
+      #   class MyClass
+      #     def setup
+      #       if database_enabled
+      #         Metasploit::Framework::Require.optionally_active_record_railtie
+      #       end
+      #     end
+      #   end
+      #
+      # @return [void]
+      def self.optionally_active_record_railtie
+        optionally(
+            'active_record/railtie',
+            'activerecord not in the bundle, so database support will be disabled.'
+        )
+      end
+
+      # Tries to `require 'metasploit/credential/creation'` and include it in the `including_module`.
+      #
+      # @param including_module [Module] `Class` or `Module` that wants to `include Metasploit::Credential::Creation`.
+      # @return [void]
+      def self.optionally_include_metasploit_credential_creation(including_module)
+        optionally(
+            'metasploit/credential/creation',
+            "metasploit-credential not in the bundle, so Metasploit::Credential creation will fail for #{including_module.name}",
+        ) do
+          including_module.send(:include, Metasploit::Credential::Creation)
+        end
+      end
+
+      #
+      # Instance Methods
+      #
+
+      # Tries to `require 'metasploit/credential/creation'` and include it in this `Class` or `Module`.
+      #
+      # @example Using in a `Module`
+      #   require 'metasploit/framework/require'
+      #
+      #   module MyModule
+      #     extend Metasploit::Framework::Require
+      #
+      #     optionally_include_metasploit_credential_creation
+      #   end
+      #
+      # @return [void]
+      def optionally_include_metasploit_credential_creation
+        Metasploit::Framework::Require.optionally_include_metasploit_credential_creation(self)
+      end
+    end
+  end
+end

lib/msf/core/auxiliary/report.rb

@@ -8,18 +8,9 @@ module Msf
 ###
 
 module Auxiliary::Report
-  begin
-    require 'metasploit/credential/creation'
-  rescue LoadError
-    warn "metasploit-credential not in the bundle, so Metasploit::Credential creation will fail for Msf::Auxiliary::Report."
-    warn "Bundle installed '--without #{Bundler.settings.without.join(' ')}'"
-    warn "To clear the without option do `bundle install --without ''` " \
-             "(the --without flag with an empty string) or " \
-             "`rm -rf .bundle` to remove the .bundle/config manually and " \
-             "then `bundle install`"
-  else
-    include Metasploit::Credential::Creation
-  end
+  extend Metasploit::Framework::Require
+
+  optionally_include_metasploit_credential_creation
 
   # This method overrides the method from Metasploit::Credential to check for an active db
   def active_db?

lib/msf/core/db.rb

@@ -55,6 +55,7 @@
 # Project
 #
 
+require 'metasploit/framework/require'
 require 'msf/core/db_manager/import_msf_xml'
 
 module Msf
@@ -155,20 +156,10 @@ class DBImportError < RuntimeError
 #
 ###
 class DBManager
-  include Msf::DBManager::ImportMsfXml
+  extend Metasploit::Framework::Require
 
-  begin
-    require 'metasploit/credential/creation'
-  rescue LoadError
-    warn "metasploit-credential not in the bundle, so Metasploit::Credential creation will fail for Msf::DBManager"
-    warn "Bundle installed '--without #{Bundler.settings.without.join(' ')}'"
-    warn "To clear the without option do `bundle install --without ''` " \
-             "(the --without flag with an empty string) or " \
-             "`rm -rf .bundle` to remove the .bundle/config manually and " \
-             "then `bundle install`"
-  else
-    include Metasploit::Credential::Creation
-  end
+  include Msf::DBManager::ImportMsfXml
+  optionally_include_metasploit_credential_creation
 
   def rfc3330_reserved(ip)
     case ip.class.to_s