zoukankan      html  css  js  c++  java
  • Python之网络编程(四)recv原理、高阶版粘包解决方案、基于UDP的socket通信

    recv原理、高阶版黏包解决方案、基于UDP的socket通信

    1. recv原理:

      • 源码解释:
        Receive up to buffersize bytes from the socket.
        接收来自socket缓冲区的字节数据,
        For the optional flags argument, see the Unix manual.
        对于这些设置的参数,可以查看Unix手册。
        When no data is available, block untilat least one byte is available or until the remote end is closed.
        当缓冲区没有数据可取时,recv会一直处于阻塞状态,直到缓冲区至少有一个字节数据可取,或者远程端关闭。
        When the remote end is closed and all data is read, return the empty string.
        关闭远程端并读取所有数据后,返回空字符串。
        
      • # 1,验证服务端缓冲区数据没有取完,又执行了recv执行,recv会继续取值。
        import socket
        phone = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        phone.connect(('127.0.0.1',8080))
        phone.send('hello'.encode('utf-8'))
        phone.close()
        
        
        
        # 2,验证服务端缓冲区取完了,又执行了recv执行,此时客户端20秒内不关闭的前提下,recv处于阻塞状态。
        import socket
        import time
        phone = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        phone.connect(('127.0.0.1',8080))
        phone.send('hello'.encode('utf-8'))
        time.sleep(20)
        
        phone.close()
        
        # 3,验证服务端缓冲区取完了,又执行了recv执行,此时客户端处于关闭状态,则recv会取到空字符串。
        import socket
        import time
        phone = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        phone.connect(('127.0.0.1',8080))
        phone.send('hello'.encode('utf-8'))
        phone.close()
        
      • # 1,验证服务端缓冲区数据没有取完,又执行了recv执行,recv会继续取值。
        
        import socket
        
        phone =socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        
        phone.bind(('127.0.0.1',8080))
        
        phone.listen(5)
        
        conn, client_addr = phone.accept()
        from_client_data1 = conn.recv(2)
        print(from_client_data1)
        from_client_data2 = conn.recv(2)
        print(from_client_data2)
        from_client_data3 = conn.recv(1)
        print(from_client_data3)
        conn.close()
        phone.close()
        
        # 2,验证服务端缓冲区取完了,又执行了recv执行,此时客户端20秒内不关闭的前提下,recv处于阻塞状态。
        
        import socket
        
        phone =socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        
        phone.bind(('127.0.0.1',8080))
        
        phone.listen(5)
        
        conn, client_addr = phone.accept()
        from_client_data = conn.recv(1024)
        print(from_client_data)
        print(111)
        conn.recv(1024) # 此时程序阻塞20秒左右,因为缓冲区的数据取完了,并且20秒内,客户端没有关闭。
        print(222)
        
        conn.close()
        phone.close()
        
        
        # 3 验证服务端缓冲区取完了,又执行了recv执行,此时客户端处于关闭状态,则recv会取到空字符串。
        
        import socket
        
        phone =socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        
        phone.bind(('127.0.0.1',8080))
        
        phone.listen(5)
        
        conn, client_addr = phone.accept()
        from_client_data1 = conn.recv(1024)
        print(from_client_data1)
        from_client_data2 = conn.recv(1024)
        print(from_client_data2)
        from_client_data3 = conn.recv(1024)
        print(from_client_data3)
        conn.close()
        phone.close()
        
        # recv空字符串: 对方客户端关闭了,且服务端的缓冲区没有数据了,我再recv取到空bytes.
        
    2. 高阶版粘包解决方案:

      • server端:

        import socket
        import subprocess
        import struct
        import json
        
        phone = socket.socket()
        phone.bind(('127.0.0.1',8897))
        
        phone.listen(3)
        print("等待接入")
        while 1:
            conn, addr = phone.accept()
            print(conn, addr)
            try:
                while 1:
                    from_client_data = conn.recv(1024)
                    if from_client_data.decode('utf-8').upper() == 'Q':
                        print('对方中断链接')
                        break
                    obj = subprocess.Popen(from_client_data.decode('utf-8'),
                                           shell=True,
                                           stdout=subprocess.PIPE,
                                           stderr=subprocess.PIPE,
                                           )
        
                    to_client_data = obj.stdout.read() + obj.stderr.read()
                    total_size = len(to_client_data)
                    dic = {'filename':'text1','MD5':120045318563413485631,'total_size':total_size}
                    head1 = json.dumps(dic).encode('utf-8')
        
                    len_head1 = len(head1)
                    head_bytes = struct.pack('i',len_head1)
                    conn.send(head_bytes)
                    conn.send(head1)
                    conn.send(to_client_data)
            except ConnectionError:
                print('对方中断网络链接')
                break
            conn.close()
        phone.close()
        
      • client端:

        import socket
        import struct
        import json
        phone = socket.socket()
        
        phone.connect(('127.0.0.1',8897))
        while 1:
            to_server_data = input('请输入内容')
            phone.send(to_server_data.encode('utf-8'))
            if to_server_data.upper() == "Q":
                print('主动退出')
                break
            if not to_server_data.strip():
                continue
            head = phone.recv(4)
            num = struct.unpack('i',head)[0]
            dic_head = phone.recv(num).decode('utf-8')
            dic = json.loads(dic_head)
            s = b''
            while len(s) < dic['total_size']:
                from_server_data = phone.recv(1024)
                s += from_server_data
            print(s.decode('gbk'))
        phone.close()
        
    3. 基于UDP协议的socket通信

      • server端:

        import socket
        udp_sk = socket.socket(type=socket.SOCK_DGRAM)   #创建一个服务器的套接字
        udp_sk.bind(('127.0.0.1',9000))        #绑定服务器套接字
        msg,addr = udp_sk.recvfrom(1024)
        print(msg)
        udp_sk.sendto(b'hi',addr)                 # 对话(接收与发送)
        udp_sk.close()                         # 关闭服务器套接字
        
      • client端:

      • import socket
        ip_port=('127.0.0.1',9000)
        udp_sk=socket.socket(type=socket.SOCK_DGRAM)
        udp_sk.sendto(b'hello',ip_port)
        back_msg,addr=udp_sk.recvfrom(1024)
        print(back_msg.decode('utf-8'),addr)
        
  • 相关阅读:
    几种开源工作流引擎的简单比较(转)
    ExecuteScalar
    机房重构---我们“重构”出了什么?
    薏米红豆粥功效及做法介绍
    Mean Shift具体介绍
    linux fork函数浅析
    html的下拉框的几个基本使用方法
    Readprocessmemory使用方法
    配置Log4j(非常具体)
    【Linux】linux经常使用基本命令
  • 原文地址:https://www.cnblogs.com/zhangdadayou/p/11431822.html
Copyright © 2011-2022 走看看