CS475: Computer Networks - TFTP Protocol (100 Points)

Assignment Goals

The goals of this assignment are:

1. To implement a protocol according to its RFC

The Assignment

A tftp Server

You should construct a file transfer server that is using the TFTP protocol (RFC 1350). Part one of this assignment involves constructing the server, while part two involves constructing the client.

Your programs should adhere to the published specifications so that they can inter-operate with existing clients and servers. The protocol follows this state machine [¹]:

You could test your server with the tftp client available under most Unix (and Unix-like) operating systems (e.g. Solaris, Linux, OpenBSD, etc.). Here is an article describing how to install and configure tftp on Ubuntu. However, if you do, note that some extensions to tftp are implemented by modern clients, rendering this spec non-backwards compatible. You’ll need to implement slightly different message formats to do so (look at the tftp OACK extensions). You might, instead, copy your server implementation and write a small client for testing instead, which is also acceptable.

Your server should handle multiple clients at the same time. You can accomplish this by putting your server code into a threaded routine, and starting the thread with the connection socket as soon as a connection is made by the primary server socket in main().

Notes

The tftp service is using port 69 which requires superuser (administrator) access rights. Since you want to be able to run your server on machines where you may not have superuser privileges, you should include the option to run the server from another (non-privileged) port.

1. Image created by staskobzar under the GPLv3 license. ↩

Submission

In your submission, please include answers to any questions asked on the assignment page in your README file. If you wrote code as part of this assignment, please describe your design, approach, and implementation in your README file as well. Finally, include answers to the following questions:

• If collaboration with a buddy was permitted, did you work with a buddy on this assignment? If so, who? If not, do you certify that this submission represents your own original work?
• Please identify any and all portions of your submission that were not originally written by you (for example, code originally written by your buddy, or anything taken or adapted from a non-classroom resource). It is always OK to use your textbook and instructor notes; however, you are certifying that any portions not designated as coming from an outside person or source are your own original work.
• Approximately how many hours it took you to finish this assignment (I will not judge you for this at all...I am simply using it to gauge if the assignments are too easy or hard)?
• Your overall impression of the assignment. Did you love it, hate it, or were you neutral? One word answers are fine, but if you have any suggestions for the future let me know.
• Any other concerns that you have. For instance, if you have a bug that you were unable to solve but you made progress, write that here. The more you articulate the problem the more partial credit you will receive (it is fine to leave this blank).

Assignment Rubric

Description	Pre-Emerging (< 50%)	Beginning (50%)	Progressing (85%)	Proficient (100%)
Algorithm Implementation (60%)	The algorithm fails on the test inputs due to major issues, or the program fails to compile and/or run	The algorithm fails on the test inputs due to one or more minor issues	The algorithm is implemented to solve the problem correctly according to given test inputs, but would fail if executed in a general case due to a minor issue or omission in the algorithm design or implementation	A reasonable algorithm is implemented to solve the problem which correctly solves the problem according to the given test inputs, and would be reasonably expected to solve the problem in the general case
Code Quality and Documentation (30%)	Code commenting and structure are absent, or code structure departs significantly from best practice, and/or the code departs significantly from the style guide	Code commenting and structure is limited in ways that reduce the readability of the program, and/or there are minor departures from the style guide	Code documentation is present that re-states the explicit code definitions, and/or code is written that mostly adheres to the style guide	Code is documented at non-trivial points in a manner that enhances the readability of the program, and code is written according to the style guide
Writeup and Submission (10%)	An incomplete submission is provided	The program is submitted, but not according to the directions in one or more ways (for example, because it is lacking a readme writeup)	The program is submitted according to the directions with a minor omission or correction needed, and with at least superficial responses to the bolded questions throughout	The program is submitted according to the directions, including a readme writeup describing the solution, and thoughtful answers to the bolded questions throughout

Please refer to the Style Guide for code quality examples and guidelines.