Switch back to Mutex/CV for response waiters

Makes use of the wait() method's timeout parameter instead of using the
Timeout class.

Author: joncave

lib/rex/post/meterpreter/packet_response_waiter.rb

@@ -27,7 +27,8 @@ def initialize(rid, completion_routine = nil, completion_param = nil)
       self.completion_routine = completion_routine
       self.completion_param   = completion_param
     else
-      self.done  = false
+      self.mutex = Mutex.new
+      self.cond  = ConditionVariable.new
     end
   end
 
@@ -48,7 +49,9 @@ def notify(response)
     if (self.completion_routine)
       self.completion_routine.call(response, self.completion_param)
     else
-      self.done = true
+      self.mutex.synchronize {
+        self.cond.signal
+      }
     end
   end
 
@@ -57,25 +60,14 @@ def notify(response)
   # If the interval is -1 we can wait forever.
   #
   def wait(interval)
-    if( interval and interval == -1 )
-      while(not self.done)
-        ::IO.select(nil, nil, nil, 0.1)
-      end
-    else
-      begin
-        Timeout.timeout(interval) {
-          while(not self.done)
-            ::IO.select(nil, nil, nil, 0.1)
-          end
-        }
-      rescue Timeout::Error
-        self.response = nil
-      end
-    end
+    interval = nil if interval and interval == -1
+    self.mutex.synchronize {
+      self.cond.wait(self.mutex, interval)
+    }
     return self.response
   end
 
-  attr_accessor :rid, :done, :response # :nodoc:
+  attr_accessor :rid, :mutex, :cond, :response # :nodoc:
   attr_accessor :completion_routine, :completion_param # :nodoc:
 end