WebSocket 协议主要用于解决Web前端与后台数据交互问题，在WebSocket技术没有被定义之前，前台与后端通信需要使用轮询的方式实现，WebSocket则是通过握手机制让客户端与服务端建立全双工通信，从而实现了更多复杂的业务需求。
在各种复杂的Web框架中往往集成有自己的WebSocket插件，而这里面隐藏了许多实现细节，下面我们将自己实现一个纯Python版的WebSocket通信功能，并用该技术实现动态绘图，远程CMD执行工具等。
前端index.html代码如下.
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<script src="https://cdn.lyshark.com/jquery/3.5.1/jquery.min.js"></script>
</head>
<body>
<ul id="content"></ul>
<form class="form">
<input type="text" placeholder="请输入发送的消息" class="message" id="message"/>
<input type="button" value="连接" id="connect" class="connect"/>
<input type="button" value="发送" id="send" class="connect"/>
</form>
<script type="text/javascript">
var oUl=document.getElementById('content');
var oConnect=document.getElementById('connect');
var oSend=document.getElementById('send');
var websocket=null;
oConnect.onclick=function(){
websocket=new WebSocket('ws://127.0.0.1:10083');
<!--客户端链接后触发-->
websocket.onopen=function(){
oUl.innerHTML+="<li>客户端已连接</li>";
}
<!--收到消息后触发-->
websocket.onmessage=function(evt){
oUl.innerHTML+="<li>"+evt.data+"</li>";
}
<!--关闭后触发-->
websocket.onclose=function(){
oUl.innerHTML+="<li>客户端已断开连接</li>";
};
<!--出错后触发-->
websocket.onerror=function(evt){
oUl.innerHTML+="<li>"+evt.data+"</li>";
};
};
oSend.onclick=function(){
if(websocket){
websocket.send($("#message").val())
}
}
</script>
</body>
</html>
后端的main.py执行处理任务,主要处理流程集中在handler_msg函数上.
import socket,struct,hashlib,base64
import threading
# 获取请求头部数据,并将请求头转换为字典
def get_headers(data):
headers = {}
data = str(data, encoding="utf-8")
header, body = data.split("\r\n\r\n", 1)
header_list = header.split("\r\n")
for i in header_list:
i_list = i.split(":", 1)
if len(i_list) >= 2:
headers[i_list[0]] = "".join(i_list[1::]).strip()
else:
i_list = i.split(" ", 1)
if i_list and len(i_list) == 2:
headers["method"] = i_list[0]
headers["protocol"] = i_list[1]
print("请求类型: {} 请求协议: {}".format(i_list[0],i_list[1]))
return headers
# 接收数据时的解码过程
def parse_payload(payload):
payload_len = payload[1] & 127
if payload_len == 126:
mask = payload[4:8]
decoded = payload[8:]
elif payload_len == 127:
mask = payload[10:14]
decoded = payload[14:]
else:
mask = payload[2:6]
decoded = payload[6:]
# 将所有数据全部收集起来，对所有字符串编码
bytes_list = bytearray()
for i in range(len(decoded)):
chunk = decoded[i] ^ mask[i % 4]
bytes_list.append(chunk)
body = str(bytes_list, encoding='utf-8')
return body
# 封装并发送数据到浏览器
def send_msg(conn, msg_bytes):
# 接收的第一个字节都是x81不变
first_byte = b"\x81"
length = len(msg_bytes)
if length < 126:
first_byte += struct.pack("B", length)
elif length <= 0xFFFF:
first_byte += struct.pack("!BH", 126, length)
else:
first_byte += struct.pack("!BQ", 127, length)
msg = first_byte + msg_bytes
conn.sendall(msg)
return True
# 从浏览器中接收数据
def recv_msg(conn):
data_recv = conn.recv(8096)
if data_recv[0:1] == b"\x81":
data_parse = parse_payload(data_recv)
return data_parse
return False
# 建立握手流程并创建 handler_msg 完成数据收发
def handler_accept(sock):
while True:
conn, addr = sock.accept()
data = conn.recv(8096)
headers = get_headers(data)
# 对请求头中的sec-websocket-key进行加密
response_tpl = "HTTP/1.1 101 Switching Protocols\r\n" \
"Upgrade:websocket\r\n" \
"Connection: Upgrade\r\n" \
"Sec-WebSocket-Accept: %s\r\n" \
"WebSocket-Location: ws://%s\r\n\r\n"
# 加盐操作,此处是H5规范定义好的
magic_string = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'
if headers.get('Sec-WebSocket-Key'):
value = headers['Sec-WebSocket-Key'] + magic_string
# 对数据进行加解密
ac = base64.b64encode(hashlib.sha1(value.encode('utf-8')).digest())
response_str = response_tpl % (ac.decode('utf-8'), headers.get("Host"))
# 相应握手包数据
conn.sendall(bytes(response_str, encoding="utf-8"))
t = threading.Thread(target=handler_msg, args=(conn, ))
t.start()
# 主函数,用于实现数据交互
def handler_msg(connect):
with connect as connect_ptr:
while True:
try:
recv = recv_msg(connect_ptr)
print("接收数据: {}".format(recv))
send_msg(connect_ptr, bytes("hello lyshark", encoding="utf-8"))
except Exception:
exit(0)
if __name__ == "__main__":
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind(("127.0.0.1", 10083))
sock.listen(5)
t = threading.Thread(target=handler_accept(sock))
t.start()
上方代码只是一个案例，让我们继续改进，增加一个动态图形绘制功能。
前端代码需要配合echarts绘图库代码如下:
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<script type="text/javascript" src="https://cdn.lyshark.com/echarts/5.0.0/echarts.min.js"></script>
</head>
<body>
<center><div id="main" style="height:400px;width:90%;border:1px solid #eecc11;padding:10px;"></div></center>
<script type="text/javascript" charset="UTF-8">
var display = function(time,cpu) {
var main = echarts.init(document.getElementById(("main")));
var option = {
xAxis: {
type: 'category',
data: time
},
yAxis: {
type: 'value'
},
series: [{
type: 'line',
smooth:0.3,
symbol: 'none',
color: 'blue',
smooth: true,
areaStyle: {
color: '#0000CD',
origin: 'start',
opacity: 0.5
},
data: cpu
}]
};
main.setOption(option,true);
};
</script>
<script type="text/javascript" charset="UTF-8">
var ws=new WebSocket('ws://127.0.0.1:10083');
var time =["","","","","","","","","",""];
var cpu = [0,0,0,0,0,0,0,0,0,0];
ws.onmessage=function(evt)
{
var recv = JSON.parse(evt.data);
time.push(recv.response[0]);
cpu.push(parseFloat(recv.response[1]));
if(time.length >=10){
time.shift();
cpu.shift();
console.log("时间:" + time + " --> CPU数据: " + cpu);
display(time,cpu)
}
}
</script>
</body>
</html>
后台我们主要代码不需要动,只需要修改handler_msg处理流程即可.
# 主函数,用于实现数据交互
def handler_msg(conn):
with conn as c:
while True:
try:
times = time.strftime("%M:%S", time.localtime())
data = psutil.cpu_percent(interval=None, percpu=True)
print("处理时间: {} --> 处理负载: {}".format(times, data))
send_msg(c, bytes(json.dumps({"response": [times, data]}), encoding="utf-8"))
time.sleep(60)
except Exception:
exit(0)
if __name__ == "__main__":
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind(("127.0.0.1", 10083))
sock.listen(5)
t = threading.Thread(target=handler_accept(sock))
t.start()
我们继续改进一个案例，实现一个批量命令行执行器，我们使用xterm库实现Web命令行，用Jquery向后端发送数据，该工具前端代码如下。
<html>
<head>
<meta charSet="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
<link rel="stylesheet" href="https://cdn.lyshark.com/xterm/xterm.css"/>
<script src="https://cdn.lyshark.com/xterm/xterm.js"></script>
<script src="https://cdn.lyshark.com/jquery/3.5.1/jquery.min.js" type="text/javascript"></script>
</head>
<body>
<div id="terminal"></div>
<input type="text" id="address" placeholder="主机范围 127.0.0.1-100" style="width:200px;height:40px"/>
<input type="text" id="command" placeholder="执行命令 ls -lh " style="width:400px;height:40px"/>
<input type="button" id="send_message" value="批量执行">
<!--实现格式化字符串-->
<script type="text/javascript">
$.format = function(source, params)
{
if (arguments.length == 1) return function()
{
var args = $.makeArray(arguments);
args.unshift(source);
return $.format.apply(this, args);
};
if (arguments.length > 2 && params.constructor != Array)
{
params = $.makeArray(arguments).slice(1);
}
if (params.constructor != Array)
{
params = [params];
}
$.each(params,
function(i, n)
{
source = source.replace(new RegExp("\\{" + i + "\\}", "g"), n);
});
return source;
};
</script>
<!--打开终端,并开始执行命令-->
<script type="text/javascript">
$(function(){
var window_width = $(window).width()-200;
var window_height = $(window).height()-300;
var term = new Terminal(
{
cols: Math.floor(window_width/9),
rows: Math.floor(window_height/20),
convertEol: true,
cursorBlink:false,
});
var sock = new WebSocket("ws://127.0.0.1:10083");
sock.onopen = function () {
term.open(document.getElementById('terminal'));
console.log('WebSocket Open');
};
sock.onmessage = function (recv) {
var data = JSON.parse(recv.data);
console.log(data['addr'] + ' -- ' + data['status']);
var temp = "\x1B[1;3;35m 地址:[ {0} ] \x1B[0m --> \x1B[1;3;33m 状态:[ {1} ] \x1B[0m";
var string = $.format(temp, data['addr'],data['status']);
term.writeln(string);
};
$('#send_message').click(function () {
var message ={"address":null,"command":null};
message['address'] = $("#address").val();
message['command'] = $("#command").val();
var send_data = JSON.stringify(message);
window.sock.send(send_data);
});
window.sock = sock;
});
</script>
后端代码需要增加一个CalculationIP来计算IP地址范围,其他的地方保持不变.
def CalculationIP(Addr_Count):
ret = []
try:
IP_Start = str(Addr_Count.split("-")[0]).split(".")
IP_Heads = str(IP_Start[0] + "." + IP_Start[1] + "." + IP_Start[2] +".")
IP_Start_Range = int(Addr_Count.split(".")[3].split("-")[0])
IP_End_Range = int(Addr_Count.split("-")[1])
for item in range(IP_Start_Range,IP_End_Range+1):
ret.append(IP_Heads+str(item))
return ret
except Exception:
return 0
def handler_msg(conn):
with conn as c:
while True:
try:
ref_json = eval(recv_msg(c))
address = ref_json.get("address")
command = ref_json.get("command")
address_list = CalculationIP(address)
for ip in address_list:
response = {'addr': ip, 'status': 'success'}
print("对主机: {} --> 执行: {}".format(ip,command))
send_msg(c, bytes(json.dumps(response) , encoding="utf-8"))
time.sleep(1)
except Exception:
exit(0)
if __name__ == "__main__":
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind(("127.0.0.1", 10083))
sock.listen(5)
t = threading.Thread(target=handler_accept(sock))
t.start()