Posted on 2010-05-05 08:00:00
Tags: FreeBSD, tftp
Thanks to the bravery (or the despair, I am not sure) of Warner Losh aka imp@, the FreeBSD base system now comes with a much needed upgrade of the TFTP server and client.
Although the code has been available for a two years already as the net/freebsd-tftp port and I used successfully and extensively in my previous job at BarNet, I never maneged (dared?) to commit it into the FreeBSD base system.
The import of the new code was announced as such:
| Share on Facebook | Share on TwitterGo ahead and merge the work edwin@ on tftpd into the tree. It is a lot better than what's in the tree now. Edwin tested it at a prior employer, but can't test it today. I've found that it works a lot better with the various uboot versions that I've used in my embedded work.
It all started when we got some new routers, which told me the following when trying to upload configuration or download images from it: The TFTP server doesn't support the blocksize option.
My curiousity was triggered, it took me some reading of RFCs and other documentation to find out what was possible and what could be done. Was plain TFTP very simple in its handshake, TFTP with options was kind of messy because of its backwards capability: The first packet returned could either be an acknowledgement of options, or the first data packet.
Going through the source code of src/libexec/tftpd and going through the code of src/usr.bin/tftp showed that there was a lot of duplicate code, and the addition of options would only increase the amount of duplicate code. After all, both the client and the server can act as a sender and receiver.
At the end, it ended up with a nearly complete rewrite of the tftp client and server. It has been tested against the following TFTP clients and servers:
- Itself (yay!)
- The standard FreeBSD tftp client and server
- The Fedora Core 6 tftp client and server
- Cisco router tftp client
- Extreme Networks tftp client
It supports the following RFCs:
- RFC1350 - THE TFTP PROTOCOL (REVISION 2)
- RFC2347 - TFTP Option Extension
- RFC2348 - TFTP Blocksize Option
- RFC2349 - TFTP Timeout Interval and Transfer Size Options
- RFC3617 - Uniform Resource Identifier (URI) Scheme and Applicability Statement for the Trivial File Transfer Protocol (TFTP)
It supports the following unofficial TFTP Options as described at http://www.compuphase.com/tftp.htm:
- blksize2 - Block size restricted to powers of 2, excluding protocol headers
- rollover - Block counter roll-over (roll back to zero or to one)
From the tftp program point of view the following things are changed:
- New commands: "blocksize", "blocksize2", "rollover" and "options"
- Development features: "debug" and "packetdrop"
If you try this tftp/tftpd implementation, please let me know if it works (or doesn't work) and against which implementaion so I can get a list of confirmed working systems.