Support for serial console for Virtual BOX and VMware using asyncio

Ref #747

.gitignore

@@ -1,4 +1,5 @@
 *.py[cod]
+__pycache__
 
 #py.test
 .cache

gns3server/compute/project.py

@@ -24,7 +24,7 @@ import zipstream
 import zipfile
 import json
 
-from uuid import UUID
+from uuid import UUID, uuid4
 from .port_manager import PortManager
 from .notification_manager import NotificationManager
 from ..config import Config
@@ -49,10 +49,13 @@ class Project:
     def __init__(self, name=None, project_id=None, path=None):
 
         self._name = name
+        if project_id:
             try:
                 UUID(project_id, version=4)
             except ValueError:
                 raise aiohttp.web.HTTPBadRequest(text="{} is not a valid UUID".format(project_id))
+        else:
+            project_id = str(uuid4())
         self._id = project_id
 
         self._nodes = set()

gns3server/compute/virtualbox/virtualbox_vm.py

@@ -30,12 +30,13 @@ import asyncio
 import xml.etree.ElementTree as ET
 
 from gns3server.utils import parse_version
-from gns3server.utils.telnet_server import TelnetServer
+from gns3server.utils.asyncio.telnet_server import AsyncioTelnetServer
-from gns3server.utils.asyncio import wait_for_file_creation, wait_for_named_pipe_creation, locked_coroutine
+from gns3server.utils.asyncio.serial import asyncio_open_serial
-from .virtualbox_error import VirtualBoxError
+from gns3server.utils.asyncio import locked_coroutine
-from ..nios.nio_udp import NIOUDP
+from gns3server.compute.virtualbox.virtualbox_error import VirtualBoxError
-from ..adapters.ethernet_adapter import EthernetAdapter
+from gns3server.compute.nios.nio_udp import NIOUDP
-from ..base_node import BaseNode
+from gns3server.compute.adapters.ethernet_adapter import EthernetAdapter
+from gns3server.compute.base_node import BaseNode
 
 if sys.platform.startswith('win'):
     import msvcrt
@@ -53,12 +54,11 @@ class VirtualBoxVM(BaseNode):
 
     def __init__(self, name, node_id, project, manager, vmname, linked_clone=False, console=None, adapters=0):
 
-        super().__init__(name, node_id, project, manager, console=console, linked_clone=linked_clone)
+        super().__init__(name, node_id, project, manager, console=console, linked_clone=linked_clone, console_type="telnet")
 
         self._maximum_adapters = 8
         self._system_properties = {}
-        self._telnet_server_thread = None
+        self._telnet_server = None
-        self._serial_pipe = None
         self._local_udp_tunnels = {}
 
         # VirtualBox settings
@@ -81,6 +81,7 @@ class VirtualBoxVM(BaseNode):
         json = {"name": self.name,
                 "node_id": self.id,
                 "console": self.console,
+                "console_type": self.console_type,
                 "project_id": self.project.id,
                 "vmname": self.vmname,
                 "headless": self.headless,
@@ -243,16 +244,7 @@ class VirtualBoxVM(BaseNode):
                                                                 self._local_udp_tunnels[adapter_number][1],
                                                                 nio)
 
-        if self._console is not None:
+        yield from self._start_console()
-            try:
-                # wait for VirtualBox to create the pipe file.
-                if sys.platform.startswith("win"):
-                    yield from wait_for_named_pipe_creation(self._get_pipe_name())
-                else:
-                    yield from wait_for_file_creation(self._get_pipe_name())
-            except asyncio.TimeoutError:
-                raise VirtualBoxError('Pipe file "{}" for remote console has not been created by VirtualBox'.format(self._get_pipe_name()))
-            self._start_remote_console()
 
         if (yield from self.check_hw_virtualization()):
             self._hw_virtualization = True
@@ -874,54 +866,21 @@ class VirtualBoxVM(BaseNode):
 
         os.makedirs(os.path.join(self.working_dir, self._vmname), exist_ok=True)
 
-    def _start_remote_console(self):
+    @asyncio.coroutine
+    def _start_console(self):
         """
         Starts remote console support for this VM.
         """
-
+        pipe = yield from asyncio_open_serial(self._get_pipe_name())
-        # starts the Telnet to pipe thread
+        server = AsyncioTelnetServer(reader=pipe, writer=pipe, binary=True, echo=True)
-        pipe_name = self._get_pipe_name()
+        self._telnet_server = yield from asyncio.start_server(server.run, '127.0.0.1', self.console)
-        if sys.platform.startswith("win"):
-            try:
-                self._serial_pipe = open(pipe_name, "a+b")
-            except OSError as e:
-                raise VirtualBoxError("Could not open the pipe {}: {}".format(pipe_name, e))
-            try:
-                self._telnet_server_thread = TelnetServer(self._vmname, msvcrt.get_osfhandle(self._serial_pipe.fileno()), self._manager.port_manager.console_host, self._console)
-            except OSError as e:
-                raise VirtualBoxError("Unable to create Telnet server: {}".format(e))
-            self._telnet_server_thread.start()
-        else:
-            try:
-                self._serial_pipe = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
-                self._serial_pipe.connect(pipe_name)
-            except OSError as e:
-                raise VirtualBoxError("Could not connect to the pipe {}: {}".format(pipe_name, e))
-            try:
-                self._telnet_server_thread = TelnetServer(self._vmname, self._serial_pipe, self._manager.port_manager.console_host, self._console)
-            except OSError as e:
-                raise VirtualBoxError("Unable to create Telnet server: {}".format(e))
-            self._telnet_server_thread.start()
 
     def _stop_remote_console(self):
         """
         Stops remote console support for this VM.
         """
-
+        if self._telnet_server:
-        if self._telnet_server_thread:
+            self._telnet_server.close()
-            if self._telnet_server_thread.is_alive():
-                self._telnet_server_thread.stop()
-                self._telnet_server_thread.join(timeout=3)
-            if self._telnet_server_thread.is_alive():
-                log.warn("Serial pipe thread is still alive!")
-            self._telnet_server_thread = None
-
-        if self._serial_pipe:
-            if sys.platform.startswith("win"):
-                win32file.CloseHandle(msvcrt.get_osfhandle(self._serial_pipe.fileno()))
-            else:
-                self._serial_pipe.close()
-            self._serial_pipe = None
 
     @asyncio.coroutine
     def adapter_add_nio_binding(self, adapter_number, nio):

gns3server/compute/vmware/vmware_vm.py

@@ -25,18 +25,16 @@ import socket
 import asyncio
 import tempfile
 
-from gns3server.utils.telnet_server import TelnetServer
 from gns3server.utils.interfaces import interfaces
-from gns3server.utils.asyncio import wait_for_file_creation, wait_for_named_pipe_creation, locked_coroutine
+from gns3server.utils.asyncio.telnet_server import AsyncioTelnetServer
+from gns3server.utils.asyncio.serial import asyncio_open_serial
+from gns3server.utils.asyncio import locked_coroutine
 from collections import OrderedDict
 from .vmware_error import VMwareError
 from ..nios.nio_udp import NIOUDP
 from ..adapters.ethernet_adapter import EthernetAdapter
 from ..base_node import BaseNode
 
-if sys.platform.startswith('win'):
-    import msvcrt
-    import win32file
 
 import logging
 log = logging.getLogger(__name__)
@@ -53,8 +51,7 @@ class VMwareVM(BaseNode):
         super().__init__(name, node_id, project, manager, console=console, linked_clone=linked_clone)
 
         self._vmx_pairs = OrderedDict()
-        self._telnet_server_thread = None
+        self._telnet_server = None
-        self._serial_pipe = None
         self._vmnets = []
         self._maximum_adapters = 10
         self._started = False
@@ -82,6 +79,7 @@ class VMwareVM(BaseNode):
         json = {"name": self.name,
                 "node_id": self.id,
                 "console": self.console,
+                "console_type": self.console_type,
                 "project_id": self.project.id,
                 "vmx_path": self.vmx_path,
                 "headless": self.headless,
@@ -440,15 +438,7 @@ class VMwareVM(BaseNode):
                     if nio:
                         yield from self._add_ubridge_connection(nio, adapter_number)
 
-            # if self._console is not None:
+            yield from self._start_console()
-            #     try:
-            #         if sys.platform.startswith("win"):
-            #             yield from wait_for_named_pipe_creation(self._get_pipe_name())
-            #         else:
-            #             yield from wait_for_file_creation(self._get_pipe_name())  # wait for VMware to create the pipe file.
-            #     except asyncio.TimeoutError:
-            #         raise VMwareError('Pipe file "{}" for remote console has not been created by VMware'.format(self._get_pipe_name()))
-            #     self._start_remote_console()
         except VMwareError:
             yield from self.stop()
             raise
@@ -797,57 +787,25 @@ class VMwareVM(BaseNode):
         serial_port = {"serial0.present": "TRUE",
                        "serial0.filetype": "pipe",
                        "serial0.filename": pipe_name,
-                       "serial0.pipe.endpoint": "server"}
+                       "serial0.pipe.endpoint": "server",
+                       "serial0.startconnected": "TRUE"}
         self._vmx_pairs.update(serial_port)
 
-    def _start_remote_console(self):
+    @asyncio.coroutine
+    def _start_console(self):
         """
         Starts remote console support for this VM.
         """
-
+        pipe = yield from asyncio_open_serial(self._get_pipe_name())
-        # starts the Telnet to pipe thread
+        server = AsyncioTelnetServer(reader=pipe, writer=pipe, binary=True, echo=True)
-        pipe_name = self._get_pipe_name()
+        self._telnet_server = yield from asyncio.start_server(server.run, '127.0.0.1', self.console)
-        if sys.platform.startswith("win"):
-            try:
-                self._serial_pipe = open(pipe_name, "a+b")
-            except OSError as e:
-                raise VMwareError("Could not open the pipe {}: {}".format(pipe_name, e))
-            try:
-                self._telnet_server_thread = TelnetServer(self.name, msvcrt.get_osfhandle(self._serial_pipe.fileno()), self._manager.port_manager.console_host, self._console)
-            except OSError as e:
-                raise VMwareError("Unable to create Telnet server: {}".format(e))
-            self._telnet_server_thread.start()
-        else:
-            try:
-                self._serial_pipe = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
-                self._serial_pipe.connect(pipe_name)
-            except OSError as e:
-                raise VMwareError("Could not connect to the pipe {}: {}".format(pipe_name, e))
-            try:
-                self._telnet_server_thread = TelnetServer(self.name, self._serial_pipe, self._manager.port_manager.console_host, self._console)
-            except OSError as e:
-                raise VMwareError("Unable to create Telnet server: {}".format(e))
-            self._telnet_server_thread.start()
 
     def _stop_remote_console(self):
         """
         Stops remote console support for this VM.
         """
-
+        if self._telnet_server:
-        if self._telnet_server_thread:
+            self._telnet_server.close()
-            if self._telnet_server_thread.is_alive():
-                self._telnet_server_thread.stop()
-                self._telnet_server_thread.join(timeout=3)
-            if self._telnet_server_thread.is_alive():
-                log.warn("Serial pipe thread is still alive!")
-            self._telnet_server_thread = None
-
-        if self._serial_pipe:
-            if sys.platform.startswith("win"):
-                win32file.CloseHandle(msvcrt.get_osfhandle(self._serial_pipe.fileno()))
-            else:
-                self._serial_pipe.close()
-            self._serial_pipe = None
 
     @asyncio.coroutine
     def start_capture(self, adapter_number, output_file):

gns3server/schemas/virtualbox.py

@@ -66,6 +66,10 @@ VBOX_CREATE_SCHEMA = {
             "maximum": 65535,
             "type": "integer"
         },
+        "console_type": {
+            "description": "Console type",
+            "enum": ["telnet"]
+        },
         "ram": {
             "description": "Amount of RAM",
             "minimum": 0,
@@ -152,6 +156,10 @@ VBOX_OBJECT_SCHEMA = {
             "maximum": 65535,
             "type": "integer"
         },
+        "console_type": {
+            "description": "Console type",
+            "enum": ["telnet"]
+        },
         "ram": {
             "description": "Amount of RAM",
             "minimum": 0,

gns3server/schemas/vmware.py

@@ -48,6 +48,10 @@ VMWARE_CREATE_SCHEMA = {
             "maximum": 65535,
             "type": "integer"
         },
+        "console_type": {
+            "description": "Console type",
+            "enum": ["telnet"]
+        },
         "headless": {
             "description": "Headless mode",
             "type": "boolean"
@@ -143,6 +147,10 @@ VMWARE_OBJECT_SCHEMA = {
             "maximum": 65535,
             "type": "integer"
         },
+        "console_type": {
+            "description": "Console type",
+            "enum": ["telnet"]
+        },
         "linked_clone": {
             "description": "Whether the VM is a linked clone or not",
             "type": "boolean"

gns3server/utils/asyncio/serial.py

@@ -0,0 +1,137 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2016 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 <http://www.gnu.org/licenses/>.
+
+import sys
+import asyncio
+
+from gns3server.utils.asyncio import wait_for_file_creation, wait_for_named_pipe_creation
+from gns3server.compute.error import NodeError
+
+"""
+This module handle connection to unix socket or Windows named pipe
+"""
+if sys.platform.startswith("win"):
+    import win32file
+    import win32pipe
+    import msvcrt
+
+
+class SerialReaderWriterProtocol(asyncio.Protocol):
+
+    def __init__(self):
+        self._output = asyncio.StreamReader()
+        self.transport = None
+
+    def read(self, n=-1):
+        return self._output.read(n=n)
+
+    def at_eof(self):
+        return self._output.at_eof()
+
+    def write(self, data):
+        if self.transport:
+            self.transport.write(data)
+
+    @asyncio.coroutine
+    def drain(self):
+        pass
+
+    def connection_made(self, transport):
+        self.transport = transport
+
+    def data_received(self, data):
+        self._output.feed_data(data)
+
+
+class WindowsPipe:
+    """
+    Write input and output stream to the same object
+    """
+
+    def __init__(self, path):
+        self._handle = open(path, "a+b")
+        self._pipe = msvcrt.get_osfhandle(self._handle.fileno())
+
+    @asyncio.coroutine
+    def read(self, n=-1):
+        (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
+        yield from asyncio.sleep(0.01)
+        return b""
+
+    def at_eof(self):
+        return False
+
+    def write(self, data):
+        win32file.WriteFile(self._pipe, data)
+
+    @asyncio.coroutine
+    def drain(self):
+        return
+
+    def close(self):
+        pass
+
+
+@asyncio.coroutine
+def _asyncio_open_serial_windows(path):
+    """
+    Open a windows named pipe
+
+    :returns: An IO like object
+    """
+
+    try:
+        yield from wait_for_named_pipe_creation(path)
+    except asyncio.TimeoutError:
+        raise NodeError('Pipe file "{}" is missing'.format(path))
+    return WindowsPipe(path)
+
+
+@asyncio.coroutine
+def _asyncio_open_serial_unix(path):
+    """
+    Open a unix socket or a windows named pipe
+
+    :returns: An IO like object
+    """
+
+    try:
+        # wait for VM to create the pipe file.
+        yield from wait_for_file_creation(path)
+    except asyncio.TimeoutError:
+        raise NodeError('Pipe file "{}" is missing'.format(path))
+
+    output = SerialReaderWriterProtocol()
+    con = yield from asyncio.get_event_loop().create_unix_connection(lambda: output, path)
+    return output
+
+
+@asyncio.coroutine
+def asyncio_open_serial(path):
+    """
+    Open a unix socket or a windows named pipe
+
+    :returns: An IO like object
+    """
+
+    if sys.platform.startswith("win"):
+        return (yield from _asyncio_open_serial_windows(path))
+    else:
+        return (yield from _asyncio_open_serial_unix(path))

gns3server/utils/asyncio/telnet_server.py

@@ -245,6 +245,7 @@ class AsyncioTelnetServer:
                     log.debug("Unhandled DONT telnet command: "
                               "{0:#x} {1:#x} {2:#x}".format(*iac_cmd))
                 elif iac_cmd[1] == WILL:
+                    if iac_cmd[2] not in [BINARY]:
                         log.debug("Unhandled WILL telnet command: "
                                   "{0:#x} {1:#x} {2:#x}".format(*iac_cmd))
                 elif iac_cmd[1] == WONT:

gns3server/utils/telnet_server.py

@@ -1,442 +0,0 @@
-# -*- 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 <http://www.gnu.org/licenses/>.
-
-# TODO: port TelnetServer to asyncio
-
-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 node_name: node name
-    :param pipe_path: path to node pipe (UNIX socket on Linux/UNIX, Named Pipe on Windows)
-    :param host: server host
-    :param port: server port
-    """
-
-    def __init__(self, node_name, pipe_path, host, port):
-
-        threading.Thread.__init__(self)
-        self._node_name = node_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
-
-        for res in socket.getaddrinfo(host, port, socket.AF_UNSPEC, socket.SOCK_STREAM, 0, socket.AI_PASSIVE):
-            af, socktype, proto, _, sa = res
-            self._server_socket = socket.socket(af, socktype, proto)
-            self._server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-            self._server_socket.bind(sa)
-            self._server_socket.listen(socket.SOMAXCONN)
-            break
-
-        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._node_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._node_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 node_name: Node name
-    :param sock: socket connection
-    :param host: IP of the Telnet client
-    :param port: port of the Telnet client
-    """
-
-    def __init__(self, node_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(node_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)