websocket
websocket的由来
我们知道http协议是短连接,一次请求一次响应,如果我们想给客户端推送消息,或者想实时的获取数据我们是怎么做的呢?
为了伪造这种效果我们用了轮询和长轮询,但是这里也有弊端,服务端只能够做出响应,且不能够主动推送消息.
那么诞生了一个新的协议,websocket协议,是基于http协议创建的.
他能够不断开连接的实时收发数据,且服务端能够主动的给客户端推送消息
websocket
介绍
#1. 什么是websocket？ 是一套协议，协议规定了： - 连接时需要握手 - 发送数据进行加密 - 连接之后不断开 #2. websocket意义? 实时的响应页面,且可以主动给客户端推送消息 #3.websocket的兼容性 ie浏览器 #4.哪些框架支持websocket? - flask gevent-websocket - django channel 以上默认不支持 -tornado 框架自带
基于flask的websocket应用
安装第三方包:
pip install gevent-websocket
基于websocket的实时投票实例:
from flask import Flask,render_template,request from geventwebsocket.handler import WebSocketHandler from gevent.pywsgi import WSGIServer import json app = Flask(__name__) USERS = { '1':{'name':'钢弹','count':0}, '2':{'name':'铁锤','count':0}, '3':{'name':'贝贝','count':100}, } # http://127.0.0.1:5000/index @app.route('/index') def index(): return render_template('index.html',users=USERS) # http://127.0.0.1:5000/message WEBSOCKET_LIST = [] @app.route('/message') def message(): ws = request.environ.get('wsgi.websocket') if not ws: print('http') return '您使用的是Http协议' WEBSOCKET_LIST.append(ws) while True: cid = ws.receive() if not cid: WEBSOCKET_LIST.remove(ws) ws.close() break old = USERS[cid]['count'] new = old + 1 USERS[cid]['count'] = new for client in WEBSOCKET_LIST: client.send(json.dumps({'cid':cid,'count':new})) if __name__ == '__main__': http_server = WSGIServer(('0.0.0.0', 5000), app, handler_class=WebSocketHandler) http_server.serve_forever()
html:
<!DOCTYPE html> <html lang="zh-CN"> <head> <meta charset="UTF-8"> <title>Title</title> <meta name="viewport" content="width=device-width, initial-scale=1"> </head> <body> <h1>丑男投票系统</h1> <ul> {% for k,v in users.items() %} <li onclick="vote({{k}})" id="id_{{k}}">{{v.name}}<span>{{v.count}}</span></li> {% endfor %} </ul> <script src="{{ url_for('static',filename='jquery-3.3.1.min.js')}}"></script> <script> var ws = new WebSocket('ws://127.0.0.1:5000/message') ws.onmessage = function (event) { /* 服务器端向客户端发送数据时，自动执行 */ // {'cid':cid,'count':new} var response = JSON.parse(event.data); $('#id_'+response.cid).find('span').text(response.count); }; function vote(cid) { ws.send(cid) } </script> </body> </html>
websocket原理
websocket原理: 1. 服务端运行,等待客户端连接 2. 客户端来连接,服务端同意. 3. 客户端立即发送一个"握手信息" 4. 服务端接受到握手信息后需要对数据进行加密,给客户端返回 -sec-WebSocket-Key + magic_string -sha1 加密 -base64 加密 双方可以互相通信 5. 客户端给服务端发送消息: 读取第二个字节的后7位 127:头10字节, 4字节masking key 126:头4字节, 4字节masking key <=125:头2字节,4字节masking key 6.服务端给客户端发送消息:
# by luffycity.com def get_headers(data): """ 将请求头格式化成字典 :param data: :return: """ header_dict = {} data = str(data, encoding='utf-8') header, body = data.split('\r\n\r\n', 1) header_list = header.split('\r\n') for i in range(0, len(header_list)): if i == 0: if len(header_list[i].split(' ')) == 3: header_dict['method'], header_dict['url'], header_dict['protocol'] = header_list[i].split(' ') else: k, v = header_list[i].split(':', 1) header_dict[k] = v.strip() return header_dict def send_msg(conn, msg_bytes): """ WebSocket服务端向客户端发送消息 :param conn: 客户端连接到服务器端的socket对象,即： conn,address = socket.accept() :param msg_bytes: 向客户端发送的字节 :return: """ import struct token = b"\x81" length = len(msg_bytes) if length < 126: token += struct.pack("B", length) elif length <= 0xFFFF: token += struct.pack("!BH", 126, length) else: token += struct.pack("!BQ", 127, length) msg = token + msg_bytes conn.send(msg) import base64 import hashlib import socket sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) sock.bind(('127.0.0.1', 8002)) sock.listen(5) #####################1. 等待用户连接################## conn, address = sock.accept() ##################2. 接收验证消息################## msg = conn.recv(8096) msg_dict = get_headers(msg) ################### 3. 对数据加密################## value = msg_dict['Sec-WebSocket-Key'] + '258EAFA5-E914-47DA-95CA-C5AB0DC85B11' ac = base64.b64encode(hashlib.sha1(value.encode('utf-8')).digest()) # print(ac,type(ac)) ################### 4.将加密后的结果返回给客户端################## 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://127.0.0.1:8002\r\n\r\n" response = response_tpl %(ac.decode('utf-8'),) conn.send(response.encode('utf-8')) ################### 5. 接收小强发送的数据################## while True: info = conn.recv(8096) payload_len = info[1] & 127 if payload_len == 127: extend_payload_len = info[2:10] mask = info[10:14] decoded = info[14:] elif payload_len == 126: extend_payload_len = info[2:4] mask = info[4:8] decoded = info[8:] else: extend_payload_len = None mask = info[2:6] decoded = info[6:] 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') print(body) ##################服务端主动推送消息################## import time time.sleep(2) #进行封包 send_msg(conn,b'123123123')
