python 缓冲区 subprocess 黏包 黏包解决方案

一.缓冲区

二.两种黏包现象

两种黏包现象:

1 连续的小包可能会被优化算法给组合到一起进行发送

黏包现象1客户端

 import socket
 BUFSIZE = 1024
 ip_prort = ('127.0.0.1',8001)

 s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)

 res = s.connect(ip_prort)

 s.send('hi'.encode('utf-8'))
 s.send('meinv'.encode('utf-8'))

黏包现象1服务端

 from socket import *
 ip_prot = ('127.0.0.1',8001)

 tcp_socket_server = socket(AF_INET,SOCK_STREAM)

 tcp_socket_server.bind(ip_prot)

 tcp_socket_server.listen(5)

 conn,addr = tcp_socket_server.accept()

 data1 = conn.recv(10)
 data2 = conn.recv(10)

 print('->>>>>',data1.decode('utf-8'))
 print('->>>>>',data2.decode('utf-8'))

 conn.close()

2 第一次如果发送的数据大小2000B接收端一次性接受大小为1024,这就导致剩下的内容会被下一次recv接收到,导致结果错乱

黏包现象2客户端

 import socket

 client = socket.socket()

 ip_prot ='127.0.0.1',8002

 client.connect(ip_prot)

 while 1:
     cmd = input('请输入指令')

     client.send(cmd.encode('utf-8'))

     server_cmd_result = client.recv(1025)

     print(server_cmd_result.decode('GBK'))

黏包现象2服务端

 import socket
 import subprocess

 server = socket.socket()

 ip_prot = '127.0.0.1', 8002

 server.bind(ip_prot)

 server.listen()

 conn, addr = server.accept()

 while 1:
     from_client_cmd = conn.recv(1024)

     print(from_client_cmd.decode('utf-8'))

     sub_obj = subprocess.Popen(
         from_client_cmd.decode('utf-8'),  # 传入的cmd命令
         shell=True,
         stdout=subprocess.PIPE,  # 正确结果的存放位置
         stderr=subprocess.PIPE  # 错误结果的存放位置
     )

     std_msg = sub_obj.stdout.read()  # 获得管道里面拿到结果

     print('指令的执行结果长度>>>>', len(std_msg))

     conn.send(std_msg)

三.黏包解决方案

客户端

 import socket
 import struct

 client = socket.socket()
 ip_port = '127.0.0.1',8001

 client.connect(ip_port)

 while 1:
     cmd = input('请输入指令')

     # 发送指令

     client.send(cmd.encode('utf-8'))

     server_res_len = client.recv(4)

     msg_len = struct.unpack('i',server_res_len)[0]

     print('来自服务器端的消息长度',msg_len)

     server_cmd_result = client.recv(msg_len)

     print(server_cmd_result.decode('GBK'))

服务端

 import socket
 import subprocess
 import struct

 server = socket.socket()
 ip_port = '127.0.0.1',8001

 server.bind(ip_port)

 server.listen()

 conn,addr  = server.accept()

 while 1:
     from_client_cmd = conn.recv(1024)

     print(from_client_cmd.decode('utf-8'))

     sub_obj = subprocess.Popen(

         from_client_cmd.decode('utf-8'),
         shell = True,
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE
     )

     std_msg = sub_obj.stdout.read()

     std_msg_len = len(std_msg)

     print('指令的执行结果长度>>>>',std_msg_len)

     msg_lenint_struct = struct.pack('i',std_msg_len)

     conn.send(msg_lenint_struct + std_msg)