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WebSocket

2024-09-25 20:22:39   204人阅读

WebSocket协议是基于TCP的一种新的协议。WebSocket最初在HTML5规范中被引用为TCP连接，作为基于TCP的套接字API的占位符。它实现了浏览器与服务器全双工(full-duplex)通信。其本质是保持TCP连接，在浏览器和服务端通过Socket进行通信。

1，启动服务端

import socketsock = 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)# 等待用户连接conn, address = sock.accept().........

启动Socket服务器后，等待用户【连接】，然后进行收发数据。

2，浏览器(客户端)连接

<script type="text/javascript">    var socket = new WebSocket("ws://127.0.0.1:8002/xxoo");    ...</script>

当客户端向服务端发送连接请求时，不仅连接还会发送【握手】信息，并等待服务端响应，至此连接才创建成功！

3，建立连接（握手）

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)# 获取客户端socket对象conn, address = sock.accept()# 获取客户端的【握手】信息data = http://www.mamicode.com/conn.recv(1024).........conn.send(‘响应【握手】信息‘)

请求和响应的【握手】信息需要遵循规则：

  • 从请求【握手】信息中提取 Sec-WebSocket-Key
  • 利用magic_string 和 Sec-WebSocket-Key 进行hmac1加密，再进行base64加密
  • 将加密结果响应给客户端

注：magic string为：258EAFA5-E914-47DA-95CA-C5AB0DC85B11

请求【握手】信息为：

GET /chatsocket HTTP/1.1Host: 127.0.0.1:8002Connection: UpgradePragma: no-cacheCache-Control: no-cacheUpgrade: websocketOrigin: http://localhost:63342Sec-WebSocket-Version: 13Sec-WebSocket-Key: mnwFxiOlctXFN/DeMt1Amg==Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits......

提取Sec-WebSocket-Key值并加密：

import socketimport base64import hashlib def get_headers(data):    """    将请求头格式化成字典    :param data:    :return:    """    header_dict = {}    data = http://www.mamicode.com/str(data, encoding=‘utf-8‘)"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%s\r\n\r\n"magic_string = ‘258EAFA5-E914-47DA-95CA-C5AB0DC85B11‘value = http://www.mamicode.com/headers[‘Sec-WebSocket-Key‘] + magic_string>

4，客户端与服务端收发数据

客户端和服务端传输数据时，需要对数据进行【封包】和【解包】。客户端的JavaScript类库已经封装【封包】和【解包】过程，但Socket服务端需要手动实现。

第一步：获取客户端发送的数据【解包】

技术分享
info = conn.recv(8096)payload_len = info[1] & 127if payload_len == 126:    extend_payload_len = info[2:4]    mask = info[4:8]    decoded = info[8:]elif payload_len == 127:    extend_payload_len = info[2:10]    mask = info[10:14]    decoded = info[14:]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)
基于Python实现解包过程（未实现长内容）

解包详细过程：

0                   1                   2                   3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1+-+-+-+-+-------+-+-------------+-------------------------------+|F|R|R|R| opcode|M| Payload len |    Extended payload length    ||I|S|S|S|  (4)  |A|     (7)     |             (16/64)           ||N|V|V|V|       |S|             |   (if payload len==126/127)   || |1|2|3|       |K|             |                               |+-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - +|     Extended payload length continued, if payload len == 127  |+ - - - - - - - - - - - - - - - +-------------------------------+|                               |Masking-key, if MASK set to 1  |+-------------------------------+-------------------------------+| Masking-key (continued)       |          Payload Data         |+-------------------------------- - - - - - - - - - - - - - - - +:                     Payload Data continued ...                :+ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +|                     Payload Data continued ...                |+---------------------------------------------------------------+

 

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