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：

 1 # Author : Kelvin
 2 # Date : 2019/2/2 17:38
 3 from socket import *
 4 import subprocess
 5 
 6 ip_conf = ("127.0.0.1", 8888)
 7 buffer_capacity = 1024
 8 tcp_server = socket(AF_INET, SOCK_STREAM)
 9 tcp_server.bind(ip_conf)
10 tcp_server.listen(5)
11 while True:
12     conn, addr = tcp_server.accept()
13     while True:
14         try:
15             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
16             print("收到的cmd：%s" % cmd)
17             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
18                 break
19             res = subprocess.Popen(cmd.decode("utf8"), shell=True, stdout=subprocess.PIPE, stdin=subprocess.PIPE,
20                                    stderr=subprocess.PIPE)
21             err = res.stderr.read()
22             if err:
23                 back_msg = err
24             else:
25                 back_msg = res.stdout.read()
26             if not back_msg:
27                 back_msg = "acute successful!".encode("gbk")
28             length = len(back_msg)
29             conn.send(str(length).encode("gbk"))
30             re_ready = conn.recv(buffer_capacity).decode("utf8")
31             if re_ready == "ready":
32                 conn.send(back_msg)
33         except Exception as e:
34             print(e)
35             break
36 tcp_server.close()

客户端：

 1 # Author : Kelvin
 2 # Date : 2019/2/2 17:38
 3 from socket import *
 4 
 5 ip_conf = ("127.0.0.1", 8888)
 6 buffer_capacity = 1024
 7 tcp_client = socket(AF_INET, SOCK_STREAM)
 8 tcp_client.connect(ip_conf)
 9 while True:
10     cmd = input("Please input cmd : ")
11     if not cmd:
12         continue
13     if cmd == "quit":
14         break
15     tcp_client.send(cmd.encode("utf8"))
16     re_size = int(tcp_client.recv(buffer_capacity).decode("utf-8"))
17     print("大小:", re_size)
18     tcp_client.send("ready".encode("utf8"))
19     recved_size = 0
20     recved_data = b""
21     while recved_size < re_size:
22         recved_data += tcp_client.recv(buffer_capacity)
23         recved_size = len(recved_data)
24     back_msg = recved_data.decode("gbk")
25     print(back_msg)
26 tcp_client.close()

升级版：

服务器：

 1 # Author : Kelvin
 2 # Date : 2019/2/2 17:38
 3 from socket import *
 4 import subprocess
 5 import struct
 6 
 7 ip_conf = ("127.0.0.1", 8888)
 8 buffer_capacity = 1024
 9 tcp_server = socket(AF_INET, SOCK_STREAM)
10 tcp_server.bind(ip_conf)
11 tcp_server.listen(5)
12 while True:
13     conn, addr = tcp_server.accept()
14     while True:
15         try:
16             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
17             print("收到的cmd：%s" % cmd)
18             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
19                 break
20             res = subprocess.Popen(cmd.decode("utf8"), shell=True, stdout=subprocess.PIPE, stdin=subprocess.PIPE,
21                                    stderr=subprocess.PIPE)
22             err = res.stderr.read()
23             if err:
24                 back_msg = err
25             else:
26                 back_msg = res.stdout.read()
27             if not back_msg:
28                 back_msg = "acute successful!".encode("gbk")
29             length = len(back_msg)
30             re_length = struct.pack("i", length)
31             conn.send(re_length)
32             conn.send(back_msg)
33         except Exception as e:
34             print(e)
35             break
36 tcp_server.close()

客户端：

 1 # Author : Kelvin
 2 # Date : 2019/2/2 17:38
 3 from socket import *
 4 import struct
 5 ip_conf = ("127.0.0.1", 8888)
 6 buffer_capacity = 1024
 7 tcp_client = socket(AF_INET, SOCK_STREAM)
 8 tcp_client.connect(ip_conf)
 9 while True:
10     cmd = input("Please input cmd : ")
11     if not cmd:
12         continue
13     if cmd == "quit":
14         break
15     tcp_client.send(cmd.encode("utf8"))
16     re_size = struct.unpack("i",tcp_client.recv(4))[0]
17     print("大小:", re_size)
18     recved_size = 0
19     recved_data = b""
20     while recved_size < re_size:
21         recved_data += tcp_client.recv(buffer_capacity)
22         recved_size = len(recved_data)
23     back_msg = recved_data.decode("gbk")
24     print(back_msg)
25 tcp_client.close()