Python实现WebSocket通信

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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。

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()