————————————Python Network Based—————————————

TCP Based Socket：

####--------Service-----------
import socket
sk = socket.socket()    
#create a socket object                        
sk.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)     #Reuse port
sk.bind(("127.0.0.1",8105))       
#Bind IP and port Numbers as tuples，     AF_INET               
sk.listen()                                       
conn,addr = sk.accept()
#block state,wait tcp connect，if sucess，return conn as socket new object，used to receive and send data               
while 1:
    ret = conn.recv(1024).decode("utf-8")
    #block state, until received a message from client    
    print(ret)
    if ret == "bye":
        conn.send(b"bye")
        break
    else:
        new_send = input(">>>")
        conn.send(bytes(new_send,encoding = "utf-8"))
conn.close()
#close TCP connect
sk.close()
#close socket object,If not, continue receiving

####--------Client-----------
import socket
sk = socket.socket()
sk.connect(("127.0.0.1",8105))
while 1:
    new_send = input(">>>")
    sk.send(bytes(new_send,encoding = 'utf-8'))    
    #Data needs to be transmitted as bit
    new_recv = sk.recv(1024).decode("utf-8")
    print(new_recv)
    if new_recv == "bye":
        break
sk.close()

 注：print("你好".encode("utf-8")) == print(bytes("你好",encoding = "utf-8"))

 UDP Based Socket

####--------Service-----------
import socket
sk = socket.socket(type=socket.SOCK_DGRAM)
sk.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
sk.bind(("127.0.0.1",8889))
while 1:
    recv,addr = sk.recvfrom(1024)
    print(recv.decode("utf-8"))
    if recv.decode("utf-8") == "bye":
        break
    else:
        new_send = input(">>>>").encode("utf-8") 
        sk.sendto(new_send,addr)
sk.close()


####--------Client-----------
import socket
sk = socket.socket(type=socket.SOCK_DGRAM)
ip_port = ("127.0.0.1",8889)
while 1:
    new_send = input(">>>> ")
    if new_send == "bye":
        sk.sendto(new_send.encode("utf-8"),ip_prot)
        break
    else:
        new_send = "王: %s" %new_send
        sk.sendto(new_send.encode("utf-8"),ip_port)
        new_recv,addr= sk.recvfrom(1024)
        print(new_recv.decode("utf-8"))
sk.close()

 Tcp Sticky Package

The reason: TCP mechanism

Scenario: 1，Continuously send two small data  --------The TCP optimization algorithm allows two send to be one send

                 2，Two recv ,The first one is small ------recv buffersize decide 

 Ex: The client to perform the shell command returns the results to the server

'''
####--------Service-----------###
conn.recv(buffersize,flags)
    Receive up to buffersize bytes from the socket.  For the optional flags
    argument, see the Unix manual.  When no data is available, block until
    at least one byte is available or until the remote end is closed.  When
    the remote end is closed and all data is read, return the empty string.
'''
import socket
sk = socket.socket()
sk.bind(("127.0.0.1",8080))
sk.listen()
conn,addr = sk.accept()
while 1:
    cmd = input("input shell command>>>  ").encode("gbk")
    if cmd == "q".encode("gbk"):
        new_send = conn.send("q".encode("gbk"))
        break
    else :
        new_send = conn.send(cmd) 
        new_recv = conn.recv(1024).decode("gbk")
        print(new_recv)        
conn.close()
sk.close()  


####--------client----------###
import socket
import subprocess
sk = socket.socket()
sk.connect(("127.0.0.1",8080))
while 1:
    new_recv = sk.recv(1024).decode("gbk")
    if  new_recv == "q":
        break
    else:
        ret  = subprocess.Popen(new_recv,shell=True,stdout=subprocess.PIPE,stderr=subprocess.PIPE)
        #shell perform new_recv,Save the correct value to PIPE vessel and error value to PIPE vessel
        sk.send(ret.stdout.read())
        sk.send(ret.stderr.read())
sk.close()

 Sticky bag solution：Essence: the receiver does not know how much data to receive

First: add a connection so that the receiver knows the length of the sender's data

Cons：add a connection：If validation mechanism is not added, num and data may be stuck　　　　

####--------Service-----------###

import socket
sk = socket.socket()
sk.bind(("127.0.0.1",8080))
sk.listen()
conn,addr = sk.accept()

while 1:
    cmd = input("input shell command>>>  ").encode("gbk")
    if cmd == "q".encode("gbk"):
        new_send = conn.send("q".encode("gbk"))
        break
    else :
        new_send = conn.send(cmd) 
        num = int(conn.recv(4096))
        print(num)
        new_send = conn.send("ok".encode("utf-8")) 
        new_recv = conn.recv(num).decode("gbk")
        print(new_recv)        
conn.close()
sk.close()


####--------client----------###
import socket
import subprocess
sk = socket.socket()
sk.connect(("127.0.0.1",8080))
while 1:
    new_recv = sk.recv(1024).decode("gbk")
    if  new_recv == "q":
        break
    else:
        ret  = subprocess.Popen(new_recv,shell=True,stdout=subprocess.PIPE,stderr=subprocess.PIPE)
        stdout = ret.stdout.read()
        stderr = ret.stderr.read()
        new_send = sk.send(str(len(stdout)+len(stderr)).encode("utf-8"))
        new_ok = sk.recv(1024).decode("utf-8")
        if new_ok == "ok":
            sk.send(stdout)
            sk.send(stderr)
sk.close()

Second：Through struct module, num is transformed into fixed byte to reduce connection.

####--------Service-----------###

import socket
import struct
sk = socket.socket()
sk.bind(("127.0.0.1",8080))
sk.listen()
conn,addr = sk.accept()

while 1:
    cmd = input("input shell command>>>  ").encode("gbk")
    if cmd == "q".encode("gbk"):
        new_send = conn.send("q".encode("gbk"))
        break
    else :
        new_send = conn.send(cmd) 
        num = conn.recv(4)
        num = struct.unpack("i",num)[0]
        new_recv = conn.recv(num).decode("gbk")
        print(new_recv)        
conn.close()
sk.close()  


####--------client----------###
import socket
import subprocess
import struct
sk = socket.socket()
sk.connect(("127.0.0.1",8080))
while 1:
    new_recv = sk.recv(1024).decode("gbk")
    if  new_recv == "q":
        break
    else:
        ret  = subprocess.Popen(new_recv,shell=True,stdout=subprocess.PIPE,stderr=subprocess.PIPE)
        stdout = ret.stdout.read()
        stderr = ret.stderr.read()
        num = len(stdout)+len(stderr)
        num = struct.pack("i",num)
        new_send = sk.send(num)
        sk.send(stdout)
        sk.send(stderr)
sk.close()