前言
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(https://jaydenwindle.com/writing/django-websockets-zero-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 (https://aliashkevich.com/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('
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('
if not len(message):
continue
await self.ws_session.send_text(message)
# print('
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("" + 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 (https://github.com/aleimu/webshell) 欢迎 star/fork!
