python学习笔记-websocket介绍
一、websocket介绍
概述
-http,socket实现，短链接，请求响应
-websocket,socket实现，双工通道，请求响应，推送
socket创建连接，不断开
二、websocket握手过程分析
socket入手
-服务端（socket服务端）
1、服务端开启socket,监听IP和端口
3、允许连接
*5、服务端接收特殊值【加密sha1,特殊值,magic string="258EAFA5-E914-47DA-95CA-C5AB0DC85B11"】
*6、加密后的值发送给客户端
-客户端（浏览器）
2、客服端发起连接请求（IP和端口）
*4、客户端生成一个xxx,【加密sha1,特殊值,magic string="258EAFA5-E914-47DA-95CA-C5AB0DC85B11"】,向服务端发送一段特殊值
*7、客户端接收到加密的值
收发数据：
三、基于python实现websocket握手
服务端：
import socket import base64 import hashlib 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) #等待用户连接 conn,address=sock.accept() #握手消息 data=conn.recv(8096) 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') for i in data.split('\r\n'): print(i) 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 #获取【握手消息】，magic string,sha1加密 #发送回客户端 headers=get_headers(data) for k,v in headers.items(): print(k,v) magic_string='258EAFA5-E914-47DA-95CA-C5AB0DC85B11' value=headers["Sec-WebSocket-Key"]+magic_string ac=base64.b64encode(hashlib.sha1(value.encode("utf-8")).digest()) 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%s\r\n\r\n" response_str = response_tpl % (ac.decode('utf-8'), headers['Host'], headers['url']) conn.send(bytes(response_str, encoding='utf-8'))
客户端浏览器
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <script> ws=new WebSocket("ws://127.0.0.1:8002"); ws.onopen=function(){ console.log(1111); } </script> </body> </html>
结果：
四、WebSocket数据解析过程
1、位运算知识回顾
1.1、位运算
10010001
右移4位：00001001
左移4位：100100010000
1.2、异或运算
都是1：1
0，1：0
0，0：0
10010001
2、WebSocket数据解析
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。
websocke服务端接收到的数据是字节，不能直接获得，要进行位运算，
例：获取的数据如下，info[0]就表示第一个字节
info=b'\x81\x85\x02\xe9\xee\xf0j\x8c\x82\x9cm'
解读：
opcode=info[0]&15 #opcode是第一个字节后四位，可通过跟15做异或运算获得
fin=info[0]>>7 #向右移7位获得
payload_len=info[1]&127 #payload_len是第二个字节与127进行运算获得。payload_len决定后面占的数据头长度
如果payload_len<126，头只占用这2个字节
如果payload_len=126，头要往后扩展2个字节，共占用4字节
如果payload_len=127（最大），头要往后扩展8个字节，共占用10字节
读取解码数据：后面数据不全占用，后面的前4个字节是masking key,后面才是客户端发送的数据，需要用masking key解密获得
解密方法，（后面的数据一个一个拿，然后一个一个解）
info = conn.recv(8096) payload_len = info[1] & 127 if 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)
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) return True
实例1：
服务端：
import socket import base64 import hashlib 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) #等待用户连接 conn,address=sock.accept() #握手消息 data=conn.recv(8096) 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') # for i in data.split('\r\n'): # print(i) 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 #获取【握手消息】，magic string,sha1加密 #发送回客户端 headers=get_headers(data) # for k,v in headers.items(): # print(k,v) magic_string='258EAFA5-E914-47DA-95CA-C5AB0DC85B11' value=headers["Sec-WebSocket-Key"]+magic_string ac=base64.b64encode(hashlib.sha1(value.encode("utf-8")).digest()) 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%s\r\n\r\n" response_str = response_tpl % (ac.decode('utf-8'), headers['Host'], headers['url']) conn.send(bytes(response_str, encoding='utf-8')) #发送消息封包 def send_msg(conn, msg_bytes): 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) return True #接收消息，处理并回复 while True: info = conn.recv(8096) payload_len = info[1] & 127 if 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) body=body+"==服务端已收到！" send_msg(conn,bytes(body,encoding="utf-8"))
客户端
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <script> ws=new WebSocket("ws://127.0.0.1:8002"); ws.onopen=function(){ console.log(1111); ws.send('hello村长'); }; ws.onmessage=function(event){ console.log(event) }; </script> </body> </html>
结果：
另外：
*客户端ws.onclose()方法是服务器中断链接时执行
*FIN和opcode是接收到的数据过长分批处理时用到
五、通过框架实现，tornado的websocket实例
要点
服务端
Handler继承自tornado.websocket.WebSocketHandler
open #建立链接
on_message #接收消息
on_close #客户端关闭链接时执行
self.write_message #发送消息
render_string 用模板引擎去渲染
客户端
ws.send #发消息
ws.onmessage #收消息
ws.onclose #服务器端关闭时运行
》实例2：聊天室功能
服务端：
import tornado.web import tornado.websocket class IndexHandler(tornado.web.RequestHandler): def get(self): self.render("index.html") class ChatHandler(tornado.websocket.WebSocketHandler): def open(self,*args,**kwargs): ''' 客户端和服务器建立链接 1、链接 2、握手 :param args: :param kwargs: :return: ''' print("欢迎。。") def on_message(self, message): print(message) message=message+'good good' self.write_message(message) def on_close(self): pass def run(): settings={ "template_path":"templates", "static_path":"static"} application=tornado.web.Application([ (r"/",IndexHandler), (r"/chat",ChatHandler), ],**settings) application.listen(8888) tornado.ioloop.IOLoop.instance().start() if __name__ == "__main__": run()
客户端：
<html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <style> .container{ border:1px solid #dddddd; height: 400px; overflow: auto; } </style> </head> <body> <div style="width:750px;margin:0 auto;"> <h1>佛学聊天室</h1> <div class="container"></div> <div class="input"> <input type="text" id="txt"/> <input type="button" value="发送" id="btn" onclick="sendMessage();" /> </div> </div> <script src="/static/jquery-3.4.1.min.js"></script> <script> ws=new WebSocket("ws://127.0.0.1:8888/chat"); ws.onmessage=function(event){ console.log(event) }; ws.onclose=function(){ }; function sendMessage() { ws.send($('#txt').val()); } </script> </body> </html>
》实例3：聊天室完善，将消息更新到聊天窗口。。
目录：
服务端：
import tornado.web import tornado.websocket class IndexHandler(tornado.web.RequestHandler): def get(self): self.render("index.html") users=set() class ChatHandler(tornado.websocket.WebSocketHandler): def open(self,*args,**kwargs): ''' 客户端和服务器建立链接 1、链接 2、握手 :param args: :param kwargs: :return: ''' users.add(self) print("欢迎光临...") def on_message(self, message): print(message) message = message + ' - -(来自iPhone 15 Pro Max)' content=self.render_string('message.html',msg=message) for client in users: client.write_message(content) def on_close(self): users.remove(self) def run(): settings={ "template_path":"templates", "static_path":"static"} application=tornado.web.Application([ (r"/",IndexHandler), (r"/chat",ChatHandler), ],**settings) application.listen(8888) tornado.ioloop.IOLoop.instance().start() if __name__ == "__main__": run()
模板message.html
<div style="margin: 20px;background-color: antiquewhite">{{ msg }}</div>
客户端：
<html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <style> .container{ border:1px solid #dddddd; height: 400px; overflow: auto; } </style> </head> <body> <div style="width:750px;margin:0 auto;"> <h1>佛学聊天室</h1> <div class="container"></div> <div class="input"> <input type="text" id="txt"/> <input type="button" value="发送" id="btn" onclick="sendMessage();" /> </div> </div> <script src="/static/jquery-3.4.1.min.js"></script> <script> ws=new WebSocket("ws://127.0.0.1:8888/chat"); ws.onmessage=function(event){ $('.container').append(event.data); }; ws.onclose=function(){ }; function sendMessage() { ws.send($('#txt').val()); } </script> </body> </html>
效果：
