Use native_arch for railfun multi and test it

lib/rex/post/meterpreter/extensions/stdapi/railgun/multicall.rb

@@ -49,7 +49,7 @@ class MultiCaller
       # needed by DLL helper
       @win_consts = win_consts
 
-      if @client.arch == ARCH_X64
+      if @client.native_arch == ARCH_X64
         @native = 'Q<'
       else
         @native = 'V'

test/modules/post/test/railgun.rb

@@ -21,7 +21,7 @@ class MetasploitModule < Msf::Post
 
   def test_api_function_calls
 
-    it "Results should include error information" do
+    it "Should include error information in the results" do
       ret = true
       result = session.railgun.kernel32.GetCurrentProcess()
       ret &&= result['GetLastError'] == 0
@@ -51,6 +51,25 @@ class MetasploitModule < Msf::Post
       ret &&= result['nSize'].to_i == result['ComputerName'].length
     end
 
+    it "Should support calling multiple functions at once" do
+      ret = true
+      multi_rail = [
+        ['kernel32', 'LoadLibraryA', ['kernel32.dll']],
+        ['kernel32', 'GetModuleHandleA', ['kernel32.dll']],
+        ['kernel32', 'GetCurrentProcessId', []]
+      ]
+      results = session.railgun.multi(multi_rail)
+      ret &&= results.length == multi_rail.length
+      results.each do |result|
+        ret &&= result['GetLastError'] == 0
+        ret &&= result['return'] != 0
+      end
+
+      # LoadLibraryA('kernel32.dll') == GetModuleHandleA('kernel32.dll')
+      ret &&= results[0]['return'] == results[1]['return']
+      ret &&= results[2]['return'] == session.sys.process.getpid
+    end
+
     it "Should support reading memory" do
       ret = true
       result = client.railgun.kernel32.GetModuleHandleA('kernel32')