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)