Pull out HTTP-specific code from PacketDispatcher

PacketDispatcher has some hardcoded assumptions about utilizing
HTTP services as the async resource. With C2 and DNS tunnels in
the pipeline, these elements need to be separated from the core
functions of async packet dispatch and moved into their own module.

This creates a new namespace for Meterpreter::HttpPacketDispatcher,
meant to be mixed in after PacketDispatcher. The module implements
only three of the original module's methods - init, shutdown, and
the :on_passive_request callback; with the first two using :super,
with the expectation of having a PacketDispatcher mixin or API
compatible namespace already in the mix.

Author: RageLtMan

lib/rex/post/meterpreter/packet_dispatcher.rb

@@ -80,71 +80,23 @@ def initialize_passive_dispatcher
     self.recv_queue   = []
     self.waiters      = []
     self.alive        = true
-
-    # Ensure that there is only one leading and trailing slash on the URI
-    resource_uri = "/" + self.conn_id.to_s.gsub(/(^\/|\/$)/, '') + "/"
-
-    self.passive_service = self.passive_dispatcher
-    self.passive_service.remove_resource(resource_uri)
-    self.passive_service.add_resource(resource_uri,
-      'Proc'             => Proc.new { |cli, req| on_passive_request(cli, req) },
-      'VirtualDirectory' => true
-    )
   end
 
   def shutdown_passive_dispatcher
-    return if not self.passive_service
-
-    # Ensure that there is only one leading and trailing slash on the URI
-    resource_uri = "/" + self.conn_id.to_s.gsub(/(^\/|\/$)/, '') + "/"
-
-    self.passive_service.remove_resource(resource_uri)
-
-    # If there are no more resources registered on the service, stop it entirely
-    if self.passive_service.resources.empty?
-      Rex::ServiceManager.stop_service(self.passive_service)
-    end
-
     self.alive      = false
     self.send_queue = []
     self.recv_queue = []
     self.waiters    = []
-
-    self.passive_service = nil
   end
 
   def on_passive_request(cli, req)
-
     begin
-
-    resp = Rex::Proto::Http::Response.new(200, "OK")
-    resp['Content-Type'] = 'application/octet-stream'
-    resp['Connection']   = 'close'
-
-    self.last_checkin = Time.now
-
-    if req.method == 'GET'
-      rpkt = send_queue.shift
-      resp.body = rpkt || ''
-      begin
-        cli.send_response(resp)
-      rescue ::Exception => e
-        send_queue.unshift(rpkt) if rpkt
-        elog("Exception sending a reply to the reader request: #{cli.inspect} #{e.class} #{e} #{e.backtrace}")
-      end
-    else
-      resp.body = ""
-      if req.body and req.body.length > 0
-        packet = Packet.new(0)
-        packet.add_raw(req.body)
-        packet.parse_header!
-        dispatch_inbound_packet(packet)
-      end
+      self.last_checkin = Time.now
+      resp = send_queue.shift
       cli.send_response(resp)
-    end
-
-    rescue ::Exception => e
-      elog("Exception handling request: #{cli.inspect} #{req.inspect} #{e.class} #{e} #{e.backtrace}")
+    rescue => e
+      send_queue.unshift(resp) if resp
+      elog("Exception sending a reply to the reader request: #{cli.inspect} #{e.class} #{e} #{e.backtrace}")
     end
   end
 
@@ -625,5 +577,70 @@ def deregister_inbound_handler(handler)
   attr_accessor :waiters # :nodoc:
 end
 
+module HttpPacketDispatcher
+  def initialize_passive_dispatcher
+    super
+
+    # Ensure that there is only one leading and trailing slash on the URI
+    resource_uri = "/" + self.conn_id.to_s.gsub(/(^\/|\/$)/, '') + "/"
+    self.passive_service = self.passive_dispatcher
+    self.passive_service.remove_resource(resource_uri)
+    self.passive_service.add_resource(resource_uri,
+      'Proc'             => Proc.new { |cli, req| on_passive_request(cli, req) },
+      'VirtualDirectory' => true
+    )
+  end
+
+  def shutdown_passive_dispatcher
+    if self.passive_service
+      # Ensure that there is only one leading and trailing slash on the URI
+      resource_uri = "/" + self.conn_id.to_s.gsub(/(^\/|\/$)/, '') + "/"
+      self.passive_service.remove_resource(resource_uri) if self.passive_service
+
+      if self.passive_service.resources.empty?
+        Rex::ServiceManager.stop_service(self.passive_service)
+      end
+      self.passive_service = nil
+    end
+    super
+  end
+
+  def on_passive_request(cli, req)
+
+    begin
+
+    resp = Rex::Proto::Http::Response.new(200, "OK")
+    resp['Content-Type'] = 'application/octet-stream'
+    resp['Connection']   = 'close'
+
+    self.last_checkin = Time.now
+
+    if req.method == 'GET'
+      rpkt = send_queue.shift
+      resp.body = rpkt || ''
+      begin
+        cli.send_response(resp)
+      rescue ::Exception => e
+        send_queue.unshift(rpkt) if rpkt
+        elog("Exception sending a reply to the reader request: #{cli.inspect} #{e.class} #{e} #{e.backtrace}")
+      end
+    else
+      resp.body = ""
+      if req.body and req.body.length > 0
+        packet = Packet.new(0)
+        packet.add_raw(req.body)
+        packet.parse_header!
+        dispatch_inbound_packet(packet)
+      end
+      cli.send_response(resp)
+    end
+
+    rescue ::Exception => e
+      elog("Exception handling request: #{cli.inspect} #{req.inspect} #{e.class} #{e} #{e.backtrace}")
+    end
+  end
+
+end
+
 end; end; end