tcp套接字粘包解决办法

粘包只会出现在tcp，udp传输不会产生粘包现象。解决粘包的原理就是服务器预先向客户端发送客户端即将获取文件的大小。

第一版解决方案：

服务器：

 # Author : Kelvin
 # Date : 2019/2/2 17:38
 from socket import *
 import subprocess

 ip_conf = ("127.0.0.1", 8888)
 buffer_capacity = 1024
 tcp_server = socket(AF_INET, SOCK_STREAM)
 tcp_server.bind(ip_conf)
 tcp_server.listen(5)
 while True:
     conn, addr = tcp_server.accept()
     while True:
         try:
             cmd = conn.recv(buffer_capacity)  # 如果强制断开连接会触发try，try正是解决强制中断连接的问题
             print("收到的cmd：%s" % cmd)
             if not cmd:  # 如果使用quit断开连接，服务器会死循环收到空，该判断正是解决此问题
                 break
             res = subprocess.Popen(cmd.decode("utf8"), shell=True, stdout=subprocess.PIPE, stdin=subprocess.PIPE,
                                    stderr=subprocess.PIPE)
             err = res.stderr.read()
             if err:
                 back_msg = err
             else:
                 back_msg = res.stdout.read()
             if not back_msg:
                 back_msg = "acute successful!".encode("gbk")
             length = len(back_msg)
             conn.send(str(length).encode("gbk"))
             re_ready = conn.recv(buffer_capacity).decode("utf8")
             if re_ready == "ready":
                 conn.send(back_msg)
         except Exception as e:
             print(e)
             break
 tcp_server.close()

客户端：

 # Author : Kelvin
 # Date : 2019/2/2 17:38
 from socket import *

 ip_conf = ("127.0.0.1", 8888)
 buffer_capacity = 1024
 tcp_client = socket(AF_INET, SOCK_STREAM)
 tcp_client.connect(ip_conf)
 while True:
     cmd = input("Please input cmd : ")
     if not cmd:
         continue
     if cmd == "quit":
         break
     tcp_client.send(cmd.encode("utf8"))
     re_size = int(tcp_client.recv(buffer_capacity).decode("utf-8"))
     print("大小:", re_size)
     tcp_client.send("ready".encode("utf8"))
     recved_size = 0
     recved_data = b""
     while recved_size < re_size:
         recved_data += tcp_client.recv(buffer_capacity)
         recved_size = len(recved_data)
     back_msg = recved_data.decode("gbk")
     print(back_msg)
 tcp_client.close()

升级版：

服务器：

 # Author : Kelvin
 # Date : 2019/2/2 17:38
 from socket import *
 import subprocess
 import struct

 ip_conf = ("127.0.0.1", 8888)
 buffer_capacity = 1024
 tcp_server = socket(AF_INET, SOCK_STREAM)
 tcp_server.bind(ip_conf)
 tcp_server.listen(5)
 while True:
     conn, addr = tcp_server.accept()
     while True:
         try:
             cmd = conn.recv(buffer_capacity)  # 如果强制断开连接会触发try，try正是解决强制中断连接的问题
             print("收到的cmd：%s" % cmd)
             if not cmd:  # 如果使用quit断开连接，服务器会死循环收到空，该判断正是解决此问题
                 break
             res = subprocess.Popen(cmd.decode("utf8"), shell=True, stdout=subprocess.PIPE, stdin=subprocess.PIPE,
                                    stderr=subprocess.PIPE)
             err = res.stderr.read()
             if err:
                 back_msg = err
             else:
                 back_msg = res.stdout.read()
             if not back_msg:
                 back_msg = "acute successful!".encode("gbk")
             length = len(back_msg)
             re_length = struct.pack("i", length)
             conn.send(re_length)
             conn.send(back_msg)
         except Exception as e:
             print(e)
             break
 tcp_server.close()

客户端：

 # Author : Kelvin
 # Date : 2019/2/2 17:38
 from socket import *
 import struct
 ip_conf = ("127.0.0.1", 8888)
 buffer_capacity = 1024
 tcp_client = socket(AF_INET, SOCK_STREAM)
 tcp_client.connect(ip_conf)
 while True:
     cmd = input("Please input cmd : ")
     if not cmd:
         continue
     if cmd == "quit":
         break
     tcp_client.send(cmd.encode("utf8"))
     re_size = struct.unpack("i",tcp_client.recv(4))[0]
     print("大小:", re_size)
     recved_size = 0
     recved_data = b""
     while recved_size < re_size:
         recved_data += tcp_client.recv(buffer_capacity)
         recved_size = len(recved_data)
     back_msg = recved_data.decode("gbk")
     print(back_msg)
 tcp_client.close()