Socket传输简单的信息以及粘包问题的解决

　　一、简单的socket程序——传输简短文字：

# -*- coding: utf-8  -*-
# -*- Author: WangHW -*-
import socket

whw_client = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
whw_client.connect(('127.0.0.1',9001))
while 1:
    cmd = input('>>>:').strip()
    if not cmd:
        continue
    whw_client.send(cmd.encode('utf-8'))
    recv_data = whw_client.recv(1024)
    data = recv_data.decode('utf-8')
    print('server data:',data)

# -*- coding: utf-8  -*-
# -*- Author: WangHW -*-
import socket

whw_server = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
whw_server.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
whw_server.bind(('127.0.0.1',9001))
whw_server.listen(5)
print('listening......')
conn,addr = whw_server.accept()
#通信循环
while 1:
    try:
        recv_data = conn.recv(1024)
        data = recv_data.decode('utf-8')
        print('client data:',data)
        conn.send(data.swapcase().encode('utf-8'))
    except ConnectionResetError:
        break
conn.close()

　　演示如下：

二、模拟SSH命令——解决粘包问题版：

　　关于粘包问题的解决方案：

　　在服务器端，由于解析出来的命令结果非常多，所以我们在发送结果之前需要先给客户端发送一个“报文”，这个报文保存着具体的命令结果的信息——其中关键的信息就是结果的长度，客户端只有知道这个结果的长度后，才能制定相应的接收规则：

# -*- coding: utf-8  -*-
# -*- Author: WangHW -*-
import socket
import json
import struct

whw_client = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
whw_client.connect(('127.0.0.1',9000))
while 1:
    try:
        cmd = input('>>>:').strip()
        if not cmd:
            continue
        #发命令
        whw_client.send(cmd.encode('utf-8'))
        #1.收报头长度
        obj = whw_client.recv(10)
        #注意structunpack出来的[0]值为长度信息
        header_size = struct.unpack('i',obj)[0]
        #2.收报头——根据报头长度来收
        header_bytes = whw_client.recv(header_size)
        #3.从报头中解析出'total_size'
        header_json = header_bytes.decode('utf-8')
        header_dic = json.loads(header_json)
        total_size = header_dic['total_size']
        #根据total_size开始接收真实的数据
        recv_size = 0
        recv_data = b''
        while recv_size < total_size:
            res = whw_client.recv(1024)
            recv_data += res
            recv_size += len(res)
        print('命令结果:
',recv_data.decode('gbk'))
    except Exception as e:
        whw_client.close()

# -*- coding: utf-8  -*-
# -*- Author: WangHW -*-
import socket
import subprocess
import json
import struct

whw_server = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
whw_server.bind(('127.0.0.1',9000))
whw_server.listen(5)
print('Listening......')
conn,addr = whw_server.accept()
while 1:
    try:
        #收命令
        cmd_recv = conn.recv(1024).decode('utf-8')
        #解析命令
        obj = subprocess.Popen(cmd_recv,shell=True,stdout=subprocess.PIPE,stderr=subprocess.PIPE)
        stdout = obj.stdout.read()
        stderr = obj.stderr.read()
        #将命令返回给客户端
        #1.制作固定报头——注意报头里面要包含数据的总长度！
        header_dic = {'filename':'whw','total_size':len(stdout)+len(stderr)}
        header_json = json.dumps(header_dic)
        header_bytes = header_json.encode('utf-8')
        #2.发送报头长度——struct:把数字打成固定长度
        conn.send(struct.pack('i',len(header_bytes)))
        #3.发送报头
        conn.send(header_bytes)
        #4.发送真实数据
        conn.send(stdout)
        conn.send(stderr)
    except ConnectionResetError:
        break

conn.close()

　　演示如下：