python- stick package, change directory

A. Stick package

　　Only tcp protocol stick package will occur, udp tcp agreement will not:

    There is a co-sourcing mechanism (Nagle algorithm), and the transmission interval of many successive small data, a data transfer to be packaged 
    there is a mechanism unpacking mechanism, because by the data card MTU restrictions, split, split into several smaller data transmission 
    when the transmission to the target host operating system layer, re-combine multiple smaller data into the original data 
Why stick udp packet does not happen?

udp stick package does not occur, a limit udp protocol and receive data according to the size of layer:
         65535 - the IP header (20) - udp header (8) = 65507 

   stand data link layer, should be in general restricted to the card MTU 1500, so that the data link layer, the size of a retransmission data is limited to
         1500 - ip header (20) - udp header (8) = 1472 

    conclusion: 
        If the sendto (NUM) 
        NUM > 65507 given
         1472 < num <65507 will unpack the data link layer, and udp itself is unreliable protocol, 
        once unpacked, the plurality of small data packets caused by transmission in the network, if any lost, then the data transmission fails 
        num <1472 is an ideal state

II. Run (subprocess)

subprocess.Popen = cmd (cmd, shell = True, stdout = subprocess.PIPE, stderr = subprocess.PIPE) 

# cmd: represents the system command 
# shell = True: This command is representative of system commands; tells the operating system, as the system cmd command 
# stdout: after performing a system command, save the results of a pipeline for 
# stderr: after performing the system command is used to save the error of a pipeline

Service-Terminal:

import socket
import subprocess

sk = socket.socket()
sk.bind(('127.0.0.1',8080))
sk.listen()

conn,addr = sk.accept()

while 1:
    msg_r = conn.recv(1024).decode('utf-8')
    result = subprocess.Popen(msg_r,shell=True,stdout=subprocess.PIPE,stderr=subprocess.PIPE)

    # print(result.stdout.read().decode('gbk'))
    # print(result.stderr.read())
    stdout = result.stdout.read()
    stderr = result.stderr.read()

    if  stderr:
       conn.send(stderr)
    else:
        conn.send(stdout)

conn.close()
sk.close()

　Client:

'' ' 
Client sends a command to execute 
server executes the command, the result of execution returns to the client 
the client to get the results are presented in front of the user 
' '' 

Import Socket 


SK = socket.socket () 
sk.connect_ex (( ' 127.0. 0.1 ' , 8080 ))
 the while . 1 : 
    cmd = iNPUT ( ' enter system commands >>> ' ) 

    sk.send (cmd.encode ( ' UTF-. 8 ' )) 

    msg_r = sk.recv (10240) .decode ( ' GBK ' )
     Print (msg_r) 

sk.close ()

III. Large file transfers

Service-Terminal:

import socket
import json
import struct

sk = socket.socket()

sk.bind(('127.0.0.1',8080))
sk.listen()

conn,addr = sk.accept()

# str_dic = conn.recv(100).decode('utf-8')
# dic = json.loads(str_dic)
# print(dic)
b_len_dic = conn.recv(4)
len_dic = struct.unpack('i',b_len_dic)[0]
str_dic = conn.recv(len_dic).decode('utf-8')
dic = json.loads(str_dic)
print(dic)

# conn.send(b'OK')

if dic['opt'] == 'upload':
    filename = '1' + dic['filename']
    with open(filename,mode='ab') as f:
        while dic['filesize']:
            content = conn.recv(1024)
            f.write(content)
            dic['filesize'] -= len(content)

conn.close()
sk.close()

Client:

Import Socket
 Import OS
 Import JSON
 Import struct　　

SK = socket.socket () 

sk.connect_ex (( ' 127.0.0.1 ' , 8080 )) 

meau = { ' . 1 ' : ' Upload ' , ' 2 ' : ' downloads ' } 
NUM = iNPUT ( ' enter optional function >>> ' ) 
DIC = { ' opt ' : meau.get (NUM), 'filename': None, ' filesize ' : None} 

file_path = INPUT ( ' Enter an absolute path >>> ' ) 
filename = os.path.basename (file_path) 
DIC [ ' filename ' ] = filename 

filesize = os.path.getsize ( file_path) 
DIC [ ' filesize ' ] = filesize 

str_dic = json.dumps (DIC) 

len_dic = len (str_dic) 
b_len_dic = struct.pack ( ' I ' , len_dic) # length packed into the dictionary data of a 4bytes
sk.send (b_len_dic + str_dic.encode ( ' UTF-8 ' )) 

# sk.recv (1024) # Why here plus a recv? It is to prevent a too fast send program execution, send the following program results in the occurrence of stick package thereto, so that data confusion occurs 



with Open (file_path, MODE = ' RB ' ) AS F:
     the while filesize: 
        Content = reached, f.read (1024 ) 
        sk.send (Content) 
        filesize - = len (Content) 

sk.close ()

IV. Change directory

Service-Terminal:

import socket
import os

sk = socket.socket()
sk.bind(('127.0.0.1', 8080))
sk.listen()

conn, addr = sk.accept()


def send_data(conn, path):
    lis_dir = os.listdir(path)
    str_dir = '__'.join(lis_dir)
    conn.send(str_dir.encode('utf-8'))


abs_path = conn.recv(1024).decode('utf-8')
current_dir = abs_path
send_data(conn, current_dir)

while 1:
    cmd = conn.recv(1024).decode('utf-8')

    if cmd == '..':
        current_dir = '/'.join(current_dir.split('\\')[:-1])
        print(current_dir)
        send_data(conn,current_dir)
    else:
        filename = cmd.split(' ')[1]
        print(filename)
        current_dir = current_dir + '//' + filename
        print(current_dir)
        if os.path.isdir(current_dir):
            send_data(conn,current_dir)
        else:
            conn.send('不是一个文件夹名'.encode('utf-8'))

conn.close()
sk.close()

Client:

import socket
import os

sk = socket.socket()

sk.connect_ex(('127.0.0.1', 8080))

abs_path = input('请输入您的根目录>>>')
sk.send(abs_path.encode('utf-8'))
current_dir = sk.recv(1024).decode('utf-8')
print(current_dir.split('__'))

while 1:
    cmd = input('>>>')

    if== cmd ' .. ' : 
        sk.send (cmd.encode ( ' UTF-. 8 ' )) 
        current_dir = sk.recv (1024) .decode ( ' UTF-. 8 ' )
         Print (current_dir.split ( ' __ ' ) )
     elif cmd == ' CD ' : 
        filename = iNPUT ( ' enter a folder name >>> ' ) 
        sk.send ((cmd + '  ' + filename) .encode ( ' UTF-. 8 '))
        current_dir = sk.recv(1024).decode('utf-8')
        print(current_dir.split('__'))

sk.close()