TFTP packet example?

Question

I'm writing a TFTP server in Ruby and I don't understand a couple things.

First, I read through the entire RFC and I understand the TFTP part of the packet (2 bytes opcode, etc), but I don't know where the TID's go. Also, I've never done anything in Ruby at a byte level. I don't know how to create a variable that's 2 bytes this and then 1 byte that and then whatever.

If someone could show me an example of how to construct a read request packet in ruby, that'd be sweet. Say I'm on the client side and I select port #20000 (for my local TID) and I want to read the file named /Users/pachun/documents/hello.txt on the server which has a TID of 69 right now because it's the first request. How would I construct that packet in Ruby?

Answer 1

Check out this project:

https://github.com/spiceworks/net-tftp

The code there should answer your questions regarding how to construct byte sequences for communicating with tftp protocol.