TFTP bug?

[BostonU SysMgr]

This is probably only of interest to those few TFTP users
(4.2bsd.)

I was getting up an implementation of tftp (server) on a
workstation and having trouble. Putting a trace at the
UDP level indicated that, when sending a file to 4.2,
ACKs were being sent to 'well-known' socket 69 although
the server was expecting only the initial request on 69
and the rest on a newly generated socket. I consulted RFC783
and pages 7-8 speak of similar behavior with sending
the initial connection request on 69 and the rest on a
'randomly' generated 'TID' so I made the following change
to /usr/src/ucb/tftp.c:

in recvfile():
	if(firsttrip) {
		...
	} else {
		sin.sin_port = from.sin_port ;	/* add this line */

and it all now works.

The question is, who was right? My suspicion
is the workstation was right so this is a
bug report but I guess I wanted a little
reassurance as it does not seem obvious.

		-Barry Shein, Boston University

P.S. I am aware of the security problems
with tftp (and you should be too before you use it)
In fact, I added a -s flag for 'secure' which demands
that file names in request packets come in
with a valid username/password (which creates new
potential problems) and performs
the reasonable setuid/setgid/chdir.
[in our server tftpd's that is]