Description
Introduction
In this lab, we will have some fun on writing a simple FTP server.
Simple FTP Server (100 Marks)
We will explore a bit of TCP. As we don’t want to delve into the topic of threading, this will be a simple
File Transfer Protocol (FTP) server. File Transfer Protocol is a bit too much so we will limit our simple
version to just 5 commands and these commands will be slightly different from the real ones.
Because you are running the client and the server on the same machine, you should create two directories
in your working directory. One called client and the other called server. These are the directories that files
from the ftp commands will be stored.
OPEN #
Attempts to open an FTP connection to 127.0.0.1 using the port number specified. Note that when testing
your program the TAs will be using ports of their choosing.
GET filename
Requests a file from the server. This file will be loaded from the server directory, transferred by the server
to the client, and saved by the client to the same name in the client directory.
PUT filename
Sends a file to the server. This file will be loaded from the client directory, transferred by the client to the
server, and saved by the server to the same name in the server directory.
CLOSE
This closes the current connection to the server but keeps the client running so that the client can connect
to another server if they wish to (and the TAs will wish to)
QUIT
Exits the client, closing any open connections
As a starting point here is a simple TCP client
from socket import *
HOST = ‘127.0.0.1’
PORT = 12000
© Fatemeh H. Fard. Not to be copied, used, or revised without express written permission from the copyright owner.
Version: September 2020 Page 2 of 3
# set up the tcp socket
sock = socket(AF_INET, SOCK_STREAM)
sock.connect((HOST, PORT))
while (True):
s = input(“Message: “)
sock.sendall(s.encode(“utf-8”))
data = sock.recv(1024).decode(“utf-8”)
if data == “QUIT”:
break
print (“Received: “, data)
sock.close()
And the server:
from socket import *
HOST = ‘127.0.0.1’
PORT = 12000
# set up the tcp socket
sock = socket(AF_INET, SOCK_STREAM)
sock.bind((HOST, PORT))
sock.listen()
# listen for a connection
conn, addr = sock.accept()
print(“Connected to ” , addr)
while (True):
data = conn.recv(1024).decode(“utf-8”).upper()
print(data)
conn.sendall(data.encode(“utf-8”))
if data == “QUIT”:
break
conn.close()
sock.close()
Submission Requirements:
A zip file containing the client and the server programs. The sample is in Python, but you are welcome to
use Java if you prefer. Screenshots of the client and server running will help if there are issues running
your programs.
© Fatemeh H. Fard. Not to be copied, used, or revised without express written permission from the copyright owner.
Version: September 2020 Page 3 of 3
NOTES:
Python has an FTP library (ftplib). The aim of this assignment is NOT to use the ftplib, rather, you write
your own simple library. Please do NOT use the ftplib (or similar existing ones in other programming
languages).
The way you should see if your program is working is as follows:
– run your server
– run your client
– open a connection using the OPEN PortNumber on the client side
– run other commands such as GET or PUT (followed by the file name)
– close the connection
Of course, this is not the proper way to test your program. But, a simple way to ensure it works.
You can send proper commands (such as print(“Received”, data) ) to see the commands are properly
received.
Please write a professional program! You need to catch exceptions if the file does not exist. Use classes
for client and server, etc. …
Advanced practices (0 points)
For those of you who want to take things to the next level, you can explore the threading options of Python
or Java and create a server that is able to support multiple connections at the same time.
