网络编程之黏包

服务端:
import socket
import subprocess
import struct
import logging
logger = logging.basicConfig(filename='粘包.txt',
                             format='%(asctime)s - %(name)s - %(levelname)s - %(module)s: %(message)s',
                             level=30)
import traceback
#创建scoket对象
server = socket.socket()
#绑定ip，端口
server.bind(('127.0.0.1',8000))
server.listen(5)
while 1:
   print('等待连接')
   conn,addr = server.accept()

   while 1:
       try:
           print('等待接受命令')
           cmd = conn.recv(1024)
           print('接受命令',cmd)
           #远程执行命令
           res = subprocess.Popen(cmd.decode('utf-8'),shell=True,
                                  stdin= subprocess.PIPE,
                                  stdout=subprocess.PIPE,
                                  stderr=subprocess.PIPE)
           #从管道读出来都是字节，只能读一次
           err = res.stderr.read()
           out = res.stdout.read()
           if  err:
               #创建报头，在一定范围内4字节
             ret = struct.pack('i',len(err))
               #发送包头
             conn.send(ret)
               #发送数据
             conn.send(err)

           elif not out:
               conn.send('命令没有返回值'.encode('utf8'))
           else:
               res =struct.pack('i',len(out))
               conn.send(res)
               conn.send(out)
               print('发送成功')
       except Exception as e:
           print(e)
           break

客户端:
import socket
import struct
import subprocess

client = socket.socket()
client.connect(('127.0.0.1',8000))
while 1:
    cmd = input('>>>')
    if cmd == 'exit':break
    elif not cmd:continue
    else:
        #发送cmd命令
        client.send(cmd.encode('utf-8'))
        print('发送成功')
        #接收报头长度,在struct模块打包长度4字节
        data_length = client.recv(4)
        #解报头长度
        data_length = struct.unpack('i',data_length)[0]
        print(data_length)
        recv_data = b""
        recv_data_length =0

        while recv_data_length < data_length :
            #接受报文
            info_data = client.recv(1024)
            #拼接报文
            recv_data += info_data
            #计算长度
            recv_data_length += len(info_data)
        print(recv_data.decode('GBK'),recv_data_length)

 3.struct模块 将数字打包到固定四字节 

import struct

ret = struct.pack('i',11112) #打包后四字节长度
print(ret,type(ret))

ret = struct.unpack('i',ret)[0] #解包返回的是元祖
print(ret,type(ret))