Fall 2017 CSE30264 Programming Assignment 2 - Simple UDP Server
Total Points: 50 points
Goal: Write a simple UDP network server
Assigned: September 13, 2017
Due: September 25, 2017 by the beginning of class
Grouping: To be developed individually
Background
You will be writing your own UDP server program for the client you have developed in programming assignment 1.
Problem:
Write a simple UDP server which provides the functionality of the server which we provided for your use in programming assignment 1. Your server should accept two command line arguments.
- The port number. (argument 1). Note that while you are testing your code, others may also be using the same port. To avoid such conflict, we assign each of you a unique port number to use when you test your code on student machines. You can find the port number assignment in the appendix.
- The encryption key. (argument 2). Your server will need to be able to work with a key between 10 to 15 alphanumeric characters.
The server needs to finish the following tasks:
- The server will use the appropriate port given by the command line argument and wait for a greeting message from a client.
- Once the server receives the greeting message, it send the encryption key to the client.
- The server will receive a message in plaintext from a client.
- The server will append a microsecond accurate time-stamp (e.g., Timestamp: 20:11:14.918623) to the message received from the client (hint: look at time(), localtime() and gettimeofday() functions in Linux/Unix), and encrypt the whole message using the simple encryption algorithm described below.
- The server will send the actual encrypted message back to the client.
- The server should then loop, and wait for the next incoming client connection.
The encryption algorithm implemented at the server is simple: for each character in the sending buffer, XOR it with the appropriate character in the key. The pseudocode is as follows:
for each char resp[x] in the sending buffer resp
resp[x] becomes the character created by XORing resp[x] with key[x modulo key length]
end for
Remember, the modulo operator (%) calculates the remainder.
Note: If the message is longer than the key, using the modulo will artificially extend the key. Also, the XORing could result in some characters being encrypted as a null character. Make sure the entire response is sent by determining the size of the message to be sent before encryption.
Also note: the server use the above algorithm to encrypt everything in the sending buffer, so your client code should implement a decryption algorithm to decrypt everything in the receiving buffer to get the right message.
Your code should not generate any console messages unless a "fatal" error occurs (can't open socket, can't connect to client, ...). In the event of such errors, your server should exit with an appropriate error code. You may wish to add a debug flag to assist you in by printing debugging information, but the debugging information should be "off" by default when you turn in your code. Servers that output debugging code will lose points.
You need to make sure that your code compiles and executes on the student 02/06 machines, and test it with your client code from programming assignment 1 on student 00/01 machines. Please do not leave orphan copies of your server and client code running on the student machines, otherwise you might lose points. You can check for orphan copies by using the command: ps -ef | grep "your assigned port number". To stop an orphan copy, take note of the pid and use the command: kill pid.
There are three test files in: /afs/nd.edu/coursefa.17/cse/cse30264.01/files/program1/ . You need to test your program using these test files or a random input string from the client. For example (xxxx is the assigned port number you use for your server, please refer to the appendix):
[netid@student06 ~] $ ./udserver xxxx key
[netid@student00 ~] $ ./udpclient student02.cse.nd.edu xxxx File1.txt
[netid@student00 ~] $ ./udpclient student06.cse.nd.edu xxxx "This is a test"
Homework Submission
Create a README file that contains a complete listing / explanation of what files are present in the directory and a commandline example to run your code.
Your source code file must contain your name and netid or it will not be graded. Create a program2 directory in your dropbox (i.e., /afs/nd.edu/coursefa.17/cse/cse30264.01/dropbox/yournetid), and copy your .c or .cpp file, and your README file to this dropbox. Please also upload a copy of the client code you used to test your server to the "program2" folder.
Note that you do not need a Makefile for this code as it should be self-contained within a single file, but you are free to submit one.
Evaluation Rubric (50 pts)
Your code will be evaluated on one of the student02/06 machines based on the following evaluation rubric.
The points for the assignment are as follows:
- 25 pts - Code mechanics
- 2 pts - Code was properly submitted.
- 3 pts - Code compiles on the server.
- 5 pts - Code executes error-free on the server.
- 5 pts - Code contains appropriate error checking.
- 5 pts - Code implements server side functions correctly.
- 5 pts - Code has an appropriate comment block including developer's name.
- 9 pts - Correct operation when the client sends the three test files used in program1.
- 3 pts - Correct operation when the client sends a random string.
- 8 pts - Add the required timestamp correctly to the message sent to client
- 5 pts - README file is present and correctly documented.
- -10 points if you leave orphan copies of your server/client code running on the student machines!
Use the port number corresponding to your name in the appendix below.
| Name |
Port Number |
| Aranguren, Maria |
41001 |
| Badart, Will |
41002 |
| Bailey, Conrad |
41003 |
| Boyd, Erica |
41004 |
| Branning, Royce |
41005 |
| Brosnan, Shane |
41006 |
| Bruscia, John |
41007 |
| Burke, Michael |
41008 |
| Byrne, Brian |
41009 |
| Carballo, Camila |
41010 |
| Cervantes, Esmeralda |
41011 |
| Chao, David |
41012 |
| Cunneen, Pierce |
41013 |
| Dalgarn, Benjamin |
41014 |
| DiFalco, Anthony |
41015 |
| Falvey, Patrick |
41016 |
| Farren, Michael |
41017 |
| Ferrara, Lauren |
41018 |
| Flanagan, Matthew |
41019 |
| Hale, Patricia |
41020 |
| Herring, Katricia |
41021 |
| Higgins, Connor |
41022 |
| Hoelting, Brianna |
41023 |
| Judson, Brenden |
41024 |
| Klenke, Collin |
41025 |
| Krueger, Randall |
41026 |
| Kusters, Madeline |
41027 |
| Lynch, Thomas |
41028 |
| Marin, Brent |
41029 |
| Marvin, James |
41030 |
| McGuinness, John |
41031 |
| Mellitt, David |
41032 |
| Michalec, Ryan |
41033 |
| Minondo, Antonio |
41034 |
| Mustipher, Sam |
41035 |
| Newell, Charles |
41036 |
| Parowski, Michael |
41037 |
| Pruitt, Mark |
41038 |
| Sherman, Bradley |
41039 |
| Simari, Robert |
41040 |
| Smick, Cameron |
41041 |
| Smick, Ryan |
41042 |
| Spencer, Joseph |
41043 |
| Syers, Laura |
41044 |
| Theisen, William |
41045 |
| Thiery, Louis |
41046 |
| Turley, Erin |
41047 |