# -*- coding: utf-8 -*- # # Copyright (C) 2014 GNS3 Technologies Inc. # # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation, either version 3 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program. If not, see . import sys import time import threading import socket import select import logging log = logging.getLogger(__name__) if sys.platform.startswith("win"): import win32pipe import win32file class TelnetServer(threading.Thread): """ Mini Telnet Server. :param vm_name: Virtual machine name :param pipe_path: path to VM pipe (UNIX socket on Linux/UNIX, Named Pipe on Windows) :param host: server host :param port: server port """ def __init__(self, vm_name, pipe_path, host, port): self._vm_name = vm_name self._pipe = pipe_path self._host = host self._port = port self._reader_thread = None self._use_thread = False self._write_lock = threading.Lock() self._clients = {} self._timeout = 1 self._alive = True if sys.platform.startswith("win"): # we must a thread for reading the pipe on Windows because it is a Named Pipe and it cannot be monitored by select() self._use_thread = True try: if ":" in self._host: # IPv6 address support self._server_socket = socket.socket(socket.AF_INET6, socket.SOCK_STREAM) else: self._server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) self._server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) self._server_socket.bind((self._host, self._port)) self._server_socket.listen(socket.SOMAXCONN) except OSError as e: log.critical("unable to create a server socket: {}".format(e)) return threading.Thread.__init__(self) log.info("Telnet server initialized, waiting for clients on {}:{}".format(self._host, self._port)) def run(self): """ Thread loop. """ while True: recv_list = [self._server_socket.fileno()] if not self._use_thread: recv_list.append(self._pipe.fileno()) for client in self._clients.values(): if client.is_active(): recv_list.append(client.socket().fileno()) else: del self._clients[client.socket().fileno()] try: client.socket().shutdown(socket.SHUT_RDWR) except OSError as e: log.warn("shutdown: {}".format(e)) client.socket().close() break try: rlist, slist, elist = select.select(recv_list, [], [], self._timeout) except OSError as e: log.critical("fatal select error: {}".format(e)) return False if not self._alive: log.info("Telnet server for {} is exiting".format(self._vm_name)) return True for sock_fileno in rlist: if sock_fileno == self._server_socket.fileno(): try: sock, addr = self._server_socket.accept() host, port = addr sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1) sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1) log.info("new client {}:{} has connected".format(host, port)) except OSError as e: log.error("could not accept new client: {}".format(e)) continue new_client = TelnetClient(self._vm_name, sock, host, port) self._clients[sock.fileno()] = new_client if self._use_thread and not self._reader_thread: self._reader_thread = threading.Thread(target=self._reader, daemon=True) self._reader_thread.start() elif not self._use_thread and sock_fileno == self._pipe.fileno(): data = self._read_from_pipe() if not data: log.warning("pipe has been closed!") return False for client in self._clients.values(): try: client.send(data) except OSError as e: log.debug(e) client.deactivate() elif sock_fileno in self._clients: try: data = self._clients[sock_fileno].socket_recv() if not data: continue # For some reason, windows likes to send "cr/lf" when you send a "cr". # Strip that so we don't get a double prompt. data = data.replace(b"\r\n", b"\n") self._write_to_pipe(data) except Exception as msg: log.info(msg) self._clients[sock_fileno].deactivate() def _write_to_pipe(self, data): """ Writes data to the pipe. :param data: data to write """ if sys.platform.startswith('win'): win32file.WriteFile(self._pipe, data) else: self._pipe.sendall(data) def _read_from_pipe(self): """ Reads data from the pipe. :returns: data """ if sys.platform.startswith('win'): (read, num_avail, num_message) = win32pipe.PeekNamedPipe(self._pipe, 0) if num_avail > 0: (error_code, output) = win32file.ReadFile(self._pipe, num_avail, None) return output return b"" else: return self._pipe.recv(1024) def _reader(self): """ Loops forever and copy everything from the pipe to the socket. """ log.debug("reader thread has started") while self._alive: try: data = self._read_from_pipe() if not data and not sys.platform.startswith('win'): log.debug("pipe has been closed! (no data)") break self._write_lock.acquire() try: for client in self._clients.values(): client.send(data) finally: self._write_lock.release() if sys.platform.startswith('win'): # sleep every 10 ms time.sleep(0.01) except Exception as e: log.debug("pipe has been closed! {}".format(e)) break log.debug("reader thread exited") self.stop() def stop(self): """ Stops the server. """ if self._alive: self._alive = False for client in self._clients.values(): client.socket().close() client.deactivate() # Mostly from https://code.google.com/p/miniboa/source/browse/trunk/miniboa/telnet.py # Telnet Commands SE = 240 # End of sub-negotiation parameters NOP = 241 # No operation DATMK = 242 # Data stream portion of a sync. BREAK = 243 # NVT Character BRK IP = 244 # Interrupt Process AO = 245 # Abort Output AYT = 246 # Are you there EC = 247 # Erase Character EL = 248 # Erase Line GA = 249 # The Go Ahead Signal SB = 250 # Sub-option to follow WILL = 251 # Will; request or confirm option begin WONT = 252 # Wont; deny option request DO = 253 # Do = Request or confirm remote option DONT = 254 # Don't = Demand or confirm option halt IAC = 255 # Interpret as Command SEND = 1 # Sub-process negotiation SEND command IS = 0 # Sub-process negotiation IS command # Telnet Options BINARY = 0 # Transmit Binary ECHO = 1 # Echo characters back to sender RECON = 2 # Reconnection SGA = 3 # Suppress Go-Ahead TMARK = 6 # Timing Mark TTYPE = 24 # Terminal Type NAWS = 31 # Negotiate About Window Size LINEMO = 34 # Line Mode class TelnetClient(object): """ Represents a Telnet client connection. :param vm_name: VM name :param sock: socket connection :param host: IP of the Telnet client :param port: port of the Telnet client """ def __init__(self, vm_name, sock, host, port): self._active = True self._sock = sock self._host = host self._port = port sock.send(bytes([IAC, WILL, ECHO, IAC, WILL, SGA, IAC, WILL, BINARY, IAC, DO, BINARY])) welcome_msg = "{} console is now available... Press RETURN to get started.\r\n".format(vm_name) sock.send(welcome_msg.encode('utf-8')) def is_active(self): """ Returns either the client is active or not. :return: boolean """ return self._active def socket(self): """ Returns the socket for this Telnet client. :returns: socket instance. """ return self._sock def send(self, data): """ Sends data to the remote end. :param data: data to send """ try: self._sock.send(data) except OSError as e: self._active = False raise Exception("Socket send: {}".format(e)) def deactivate(self): """ Sets the client to disconnect on the next server poll. """ self._active = False def socket_recv(self): """ Called by Telnet Server when data is ready. """ try: buf = self._sock.recv(1024) except BlockingIOError: return None except ConnectionResetError: buf = b'' # is the connection closed? if not buf: raise Exception("connection closed by {}:{}".format(self._host, self._port)) # Process and remove any telnet commands from the buffer if IAC in buf: buf = self._IAC_parser(buf) return buf def _read_block(self, bufsize): """ Reads a block for data from the socket. :param bufsize: size of the buffer :returns: data read """ buf = self._sock.recv(1024, socket.MSG_WAITALL) # If we don't get everything we were looking for then the # client probably disconnected. if len(buf) < bufsize: raise Exception("connection closed by {}:{}".format(self._host, self._port)) return buf def _IAC_parser(self, buf): """ Processes and removes any Telnet commands from the buffer. :param buf: buffer :returns: buffer minus Telnet commands """ skip_to = 0 while self._active: # Locate an IAC to process iac_loc = buf.find(IAC, skip_to) if iac_loc < 0: break # Get the TELNET command iac_cmd = bytearray([IAC]) try: iac_cmd.append(buf[iac_loc + 1]) except IndexError: buf.extend(self._read_block(1)) iac_cmd.append(buf[iac_loc + 1]) # Is this just a 2-byte TELNET command? if iac_cmd[1] not in [WILL, WONT, DO, DONT]: if iac_cmd[1] == AYT: log.debug("Telnet server received Are-You-There (AYT)") self._sock.send(b'\r\nYour Are-You-There received. I am here.\r\n') elif iac_cmd[1] == IAC: # It's data, not an IAC iac_cmd.pop() # This prevents the 0xff from being # interrupted as yet another IAC skip_to = iac_loc + 1 log.debug("Received IAC IAC") elif iac_cmd[1] == NOP: pass else: log.debug("Unhandled telnet command: " "{0:#x} {1:#x}".format(*iac_cmd)) # This must be a 3-byte TELNET command else: try: iac_cmd.append(buf[iac_loc + 2]) except IndexError: buf.extend(self._read_block(1)) iac_cmd.append(buf[iac_loc + 2]) # We do ECHO, SGA, and BINARY. Period. if iac_cmd[1] == DO and iac_cmd[2] not in [ECHO, SGA, BINARY]: self._sock.send(bytes([IAC, WONT, iac_cmd[2]])) log.debug("Telnet WON'T {:#x}".format(iac_cmd[2])) else: log.debug("Unhandled telnet command: " "{0:#x} {1:#x} {2:#x}".format(*iac_cmd)) # Remove the entire TELNET command from the buffer buf = buf.replace(iac_cmd, b'', 1) # Return the new copy of the buffer, minus telnet commands return buf if __name__ == '__main__': logging.basicConfig(level=logging.INFO) if sys.platform.startswith('win'): import msvcrt pipe_name = r'\\.\pipe\VBOX\Linux_Microcore_4.7.1' pipe = open(pipe_name, 'a+b') telnet_server = TelnetServer("VBOX", msvcrt.get_osfhandle(pipe.fileno()), "127.0.0.1", 3900) else: pipe_name = "/tmp/pipe_test" try: unix_socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) unix_socket.connect(pipe_name) except OSError as e: print("Could not connect to UNIX socket {}: {}".format(pipe_name, e)) sys.exit(False) telnet_server = TelnetServer("VBOX", unix_socket, "127.0.0.1", 3900) telnet_server.setDaemon(True) telnet_server.start() try: telnet_server.join() except KeyboardInterrupt: telnet_server.stop() telnet_server.join(timeout=3)