python的socket编程

Posted 2022-03-21 akiz

socket

Socket是网络编程的一个抽象概念。通常我们用一个Socket表示“打开了一个网络链接”，而打开一个Socket需要知道目标计算机的IP地址和端口号，再指定协议类型即可。

socket参数

socket地址族

socket.``AF_UNIX  unix本机进程间通信 
socket.``AF_INET  ipv4
socket.``AF_INET6  ipv6

socket类型

socket.``SOCK_STREAM  TCP
socket.``SOCK_DGRAM   UDP
socket.``SOCK_RAW    #原始套接字，普通的套接字无法处理ICMP、IGMP等网络报文，而SOCK_RAW可以；其次，SOCK_RAW也可以处理特殊的IPv4报文；此外，利用原始套接字，可以通过IP_HDRINCL套接字选项由用户构造IP头。
socket.``SOCK_RDM    #是一种可靠的UDP形式，即保证交付数据报但不保证顺序。SOCK_RAM用来提供对原始协议的低级访问，在需要执行某些特殊操作时使用，如发送ICMP报文。SOCK_RAM通常仅限于高级用户或管理员运行的程序使用。
socket.``SOCK_SEQPACKET #不使用了

socket方法

socket.socket`(family=AF_INET, type=SOCK_STREAM, proto=0, fileno=None)

socket.``accept()?

socket.``bind(address)?

socket.``close()?

socket.``getblocking()?

socket.``setblocking(flag)?

socket.``listen([backlog])?

socket.``send(bytes[, flags])?

socket.``sendall(bytes[, flags])?

socket.``sendto(bytes, address)?

socket.``sendto(bytes, flags, address)

socket.``recv(bufsize[, flags])?

socket.``recvfrom(bufsize[, flags]))?

TCP编程

TCP客户端和服务器端的交互过程

==注意：3.7.3测试多个TCP客户端，当客户端非正常断开，服务器程序也会崩掉==

例子1：简单的ssh的socket服务器客户端

有几个问题需要注意的：

• 问题1：socket每次接收和发送都有最大数据量限制的，发送的数据最大量的限制 就是缓冲区能缓存的数据的最大量。
• 问题2：粘包问题，即服务器端你调用时send 2次，但你send调用时，数据其实并没有立刻被发送给客户端，而是放到了系统的socket发送缓冲区里，等缓冲区满了、或者数据等待超时了，数据才会被send到客户端，这样就把好几次的小数据拼成一个大数据，统一发送到客户端了，这么做的目地是为了提高io利用效率，一次性发送总比连发好几次效率高嘛。 但也带来一个问题，就是“粘包”，即2次或多次的数据粘在了一起统一发送了。
• 解决办法：
• 1.服务器发送数据包的大小，再发送数据包，客户端根据数据包的大小判断数据是否完全接收
• 2.两次send出现的粘包问题
  • 方法1,time.sleep（0.5）秒，缓存区超时，就会把数据发送给客户端（不建议）
  • 方法2，在两次send之间,服务器设置一个rev,客户端设置一个send。在客户端不发送确认报文。服务器端不会主动的发送第2次的sendall数据，从而达到两次send的数据隔开。

#客户端
import socket

if __name__ == '__main__':
    server_ip = "localhost"
    server_port = 9999
    client = socket.socket()

    client.connect((server_ip, server_port))
    while True:
        msg = input(">>:").strip()
        if not msg:
            continue
        client.send(msg.encode('utf-8'))
        res_recv_size = client.recv(1024).decode()
        client.send("ACK应答".encode("utf-8"))
        total_res_size = int(res_recv_size)
        print("收到指令结果的大小:%s" % total_res_size)
        recv_res_size = 0
        cmd_res = b''
        while recv_res_size != total_res_size:
            data = client.recv(1024)
            recv_res_size += len(data)
            cmd_res += data
            print(recv_res_size)
        else:
            print("数据收完了！！")
            print(cmd_res.decode())


    client.close()
    
#服务器端
import socket
import os
if __name__ == '__main__':
    server = socket.socket()
    server.setblocking(True)
    server.bind(("localhost", 9999))
    server.listen(5)
    while True:
        print("等待新连接。。。")
        conn, addr = server.accept()
        print("新连接接入", addr)
        while True:
            data = conn.recv(1024)
            if not data:
                print("客户端断开连接")
                break
            print("收到数据%s" % data)
            res = os.popen(data.decode()).read()
            if len(res):
                conn.send(str(len(res)).encode('utf-8'))
                print("等待客户ack应答...")
                client_final_ack = conn.recv(1024)  # 等待客户端响应
                print("客户应答:", client_final_ack.decode())
                conn.sendall(res.encode("utf-8"))
            else:
                conn.send(b"command error")
    server.close()

UDP编程

#服务器端
import socket

if __name__ == '__main__':
    server = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    server.bind(("localhost", 9999))
    data, addr = server.recvfrom(1024)
    print("收到数据：", data.decode())
    print("发送人：", addr)
    server.sendto(data, addr)
    server.close()
    
#客户端
import socket

if __name__ == '__main__':
    client = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    data = b'hello world'
    HOST, PORT = "localhost", 9999
    client.sendto(data, (HOST, PORT))
    data, addr = client.recvfrom(1024)
    print(data.decode(), addr)
    client.close()

socketserver

socketserver — A framework for network servers?

同步

• class socketserver.``TCPServer(server_address, RequestHandlerClass, bind_and_activate=True)

  This uses the Internet TCP protocol, which provides for continuous streams of data between the client and server. If bind_and_activate is true, the constructor automatically attempts to invoke server_bind() andserver_activate(). The other parameters are passed to the BaseServer base class.

• class socketserver.``UDPServer(server_address, RequestHandlerClass, bind_and_activate=True)

  This uses datagrams, which are discrete packets of information that may arrive out of order or be lost while in transit. The parameters are the same as for TCPServer.

• class socketserver.``UnixStreamServer(server_address, RequestHandlerClass, bind_and_activate=True)

• class socketserver.``UnixDatagramServer(server_address, RequestHandlerClass, bind_and_activate=True)

  These more infrequently used classes are similar to the TCP and UDP classes, but use Unix domain sockets; they’re not available on non-Unix platforms. The parameters are the same as for TCPServer.

异步

• class socketserver.``ForkingTCPServer?
• class socketserver.``ForkingUDPServer?
• class socketserver.``ThreadingTCPServer?
• class socketserver.``ThreadingUDPServer?

简单TCP的sockeserver

#服务器端
import socketserver

class Myhandle(socketserver.BaseRequestHandler):
    def handle(self):
        self.data = self.request.recv(1024).decode()
        print(self.data)
        self.request.sendall(self.data.upper().encode("utf-8"))

if __name__ == '__main__':
    HOST, PORT = "localhost", 9999
    server = socketserver.TCPServer((HOST, PORT), Myhandle) #单线程
    # server = socketserver.ThreadingTCPServer((HOST, PORT), Myhandle)  #多线程
    server.serve_forever()
    
#客户端
import socket

if __name__ == '__main__':
    server_ip = "localhost"
    server_port = 9999
    client = socket.socket()

    client.connect((server_ip, server_port))
    while True:
        msg = input(">>:").strip()
        if not msg:
            continue
        client.send(msg.encode('utf-8'))
        data = client.recv(1024)
        print(data.decode())


    client.close()