Django3基于WebSocket实现WebShell的详细过程(都是服务)

最近工作中需要开发前端操作远程虚拟机的功能,简称WebShell. 基于当前的技术栈为react+django,调研了一会发现大部分的后端实现都是django+channels来实现websocket服务.
大致看了下觉得这不够有趣,翻了翻django的官方文档发现django原生是不支持websocket的,但django3之后支持了asgi协议可以自己实现websocket服务. 于是选定
gunicorn+uvicorn+asgi+websocket+django3.2+paramiko来实现WebShell.

实现websocket服务

使用django自带的脚手架生成的项目会自动生成asgi.py和wsgi.py两个文件,普通应用大部分用的都是wsgi.py配合nginx部署线上服务. 这次主要使用asgi.py
实现websocket服务的思路大致网上搜一下就能找到,主要就是实现 connect/send/receive/disconnect这个几个动作的处理方法.
这里 How to Add Websockets to a Django App without Extra Dependencies 就是一个很好的实例
, 但过于简单........:

思路

# asgi.py 
import os
from django.core.asgi import get_asgi_application
from websocket_app.websocket import websocket_application
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'websocket_app.settings')
django_application = get_asgi_application()

async def application(scope, receive, send):
 if scope['type'] == 'http':
  await django_application(scope, receive, send)
 elif scope['type'] == 'websocket':
  await websocket_application(scope, receive, send)
 else:
  raise NotImplementedError(f"Unknown scope type {scope['type']}")

# websocket.py
async def websocket_application(scope, receive, send):
 pass

# websocket.py
async def websocket_application(scope, receive, send):
 while True:
  event = await receive()
  if event['type'] == 'websocket.connect':
await send({
 'type': 'websocket.accept'
})
  if event['type'] == 'websocket.disconnect':
break
  if event['type'] == 'websocket.receive':
if event['text'] == 'ping':
 await send({
  'type': 'websocket.send',
  'text': 'pong!'
 })

实现

上面的代码提供了思路,比较完整的可以参考这里 websockets-in-django-3-1 基本可以复用了
其中最核心的实现部分我放下面:

class WebSocket:
 def __init__(self, scope, receive, send):
  self._scope = scope
  self._receive = receive
  self._send = send
  self._client_state = State.CONNECTING
  self._app_state = State.CONNECTING
 @property
 def headers(self):
  return Headers(self._scope)
 @property
 def scheme(self):
  return self._scope["scheme"]
 @property
 def path(self):
  return self._scope["path"]
 @property
 def query_params(self):
  return QueryParams(self._scope["query_string"].decode())
 @property
 def query_string(self) -> str:
  return self._scope["query_string"]
 @property
 def scope(self):
  return self._scope
 async def accept(self, subprotocol: str = None):
  """Accept connection.
  :param subprotocol: The subprotocol the server wishes to accept.
  :type subprotocol: str, optional
  """
  if self._client_state == State.CONNECTING:
await self.receive()
  await self.send({"type": SendEvent.ACCEPT, "subprotocol": subprotocol})
 async def close(self, code: int = 1000):
  await self.send({"type": SendEvent.CLOSE, "code": code})
 async def send(self, message: t.Mapping):
  if self._app_state == State.DISCONNECTED:
raise RuntimeError("WebSocket is disconnected.")
  if self._app_state == State.CONNECTING:
assert message["type"] in {SendEvent.ACCEPT, SendEvent.CLOSE}, (
  'Could not write event "%s" into socket in connecting state.'
  % message["type"]
)
if message["type"] == SendEvent.CLOSE:
 self._app_state = State.DISCONNECTED
else:
 self._app_state = State.CONNECTED
  elif self._app_state == State.CONNECTED:
assert message["type"] in {SendEvent.SEND, SendEvent.CLOSE}, (
  'Connected socket can send "%s" and "%s" events, not "%s"'
  % (SendEvent.SEND, SendEvent.CLOSE, message["type"])
)
if message["type"] == SendEvent.CLOSE:
 self._app_state = State.DISCONNECTED
  await self._send(message)
 async def receive(self):
  if self._client_state == State.DISCONNECTED:
raise RuntimeError("WebSocket is disconnected.")
  message = await self._receive()
  if self._client_state == State.CONNECTING:
assert message["type"] == ReceiveEvent.CONNECT, (
  'WebSocket is in connecting state but received "%s" event'
  % message["type"]
)
self._client_state = State.CONNECTED
  elif self._client_state == State.CONNECTED:
assert message["type"] in {ReceiveEvent.RECEIVE, ReceiveEvent.DISCONNECT}, (
  'WebSocket is connected but received invalid event "%s".'
  % message["type"]
)
if message["type"] == ReceiveEvent.DISCONNECT:
 self._client_state = State.DISCONNECTED
  return message

缝合怪

做为合格的代码搬运工,为了提高搬运效率还是要造点轮子填点坑的,如何将上面的WebSocket类与paramiko结合起来实现从前端接受字符传递给远程主机并同时接受返回呢?

import asyncio
import traceback
import paramiko
from webshell.ssh import Base, RemoteSSH
from webshell.connection import WebSocket

class WebShell:
 """整理 WebSocket 和 paramiko.Channel,实现两者的数据互通"""
 def __init__(self, ws_session: WebSocket,
  ssh_session: paramiko.SSHClient = None,
  chanel_session: paramiko.Channel = None
  ):
  self.ws_session = ws_session
  self.ssh_session = ssh_session
  self.chanel_session = chanel_session
 def init_ssh(self, host=None, port=22, user="admin", passwd="admin@123"):
  self.ssh_session, self.chanel_session = RemoteSSH(host, port, user, passwd).session()
 def set_ssh(self, ssh_session, chanel_session):
  self.ssh_session = ssh_session
  self.chanel_session = chanel_session
 async def ready(self):
  await self.ws_session.accept()
 async def welcome(self):
  # 展示Linux欢迎相关内容
  for i in range(2):
if self.chanel_session.send_ready():
 message = self.chanel_session.recv(2048).decode('utf-8')
 if not message:
  return
 await self.ws_session.send_text(message)
 async def web_to_ssh(self):
  # print('--------web_to_ssh------->')
  while True:
# print('--------------->')
if not self.chanel_session.active or not self.ws_session.status:
 return
await asyncio.sleep(0.01)
shell = await self.ws_session.receive_text()
# print('-------shell-------->', shell)
if self.chanel_session.active and self.chanel_session.send_ready():
 self.chanel_session.send(bytes(shell, 'utf-8'))
# print('--------------->', "end")
 async def ssh_to_web(self):
  # print('<--------ssh_to_web-----------')
  while True:
# print('<-------------------')
if not self.chanel_session.active:
 await self.ws_session.send_text('ssh closed')
 return
if not self.ws_session.status:
 return
await asyncio.sleep(0.01)
if self.chanel_session.recv_ready():
 message = self.chanel_session.recv(2048).decode('utf-8')
 # print('<---------message----------', message)
 if not len(message):
  continue
 await self.ws_session.send_text(message)
# print('<-------------------', "end")
 async def run(self):
  if not self.ssh_session:
raise Exception("ssh not init!")
  await self.ready()
  await asyncio.gather(
self.web_to_ssh(),
self.ssh_to_web()
  )
 def clear(self):
  try:
self.ws_session.close()
  except Exception:
traceback.print_stack()
  try:
self.ssh_session.close()
  except Exception:
traceback.print_stack()

前端

xterm.js 完全满足,搜索下找个看着简单的就行.

export class Term extends React.Component {
 private terminal!: HTMLDivElement;
 private fitAddon = new FitAddon();
 componentDidMount() {
  const xterm = new Terminal();
  xterm.loadAddon(this.fitAddon);
  xterm.loadAddon(new WebLinksAddon());
  // using wss for https
  //const socket = new WebSocket("ws://" + window.location.host + "/api/v1/ws");
  const socket = new WebSocket("ws://localhost:8000/webshell/");
  // socket.onclose = (event) => {
  //  this.props.onClose();
  // }
  socket.onopen = (event) => {
xterm.loadAddon(new AttachAddon(socket));
this.fitAddon.fit();
xterm.focus();
  }
  xterm.open(this.terminal);
  xterm.onResize(({ cols, rows }) => {
socket.send("<RESIZE>" + cols + "," + rows)
  });
  window.addEventListener('resize', this.onResize);
 }
 componentWillUnmount() {
  window.removeEventListener('resize', this.onResize);
 }
 onResize = () => {
  this.fitAddon.fit();
 }
 render() {
  return <div className="Terminal" ref={(ref) => this.terminal = ref as HTMLDivElement}></div>;
 }
}

好了,废话不多少了,代码我放这里了webshell 欢迎star/fork!