Syslinux - Mar 2007 - dynamic tftp content?

Hi.

Has there ever been any consideration to allowing the tftp server to 
provide dynamic content?

The problem I am trying to solve is the following... I would like to 
create an app to configure new systems.
Part of that is to pxe boot them.

My understanding of the process is:
1) server comes up and gets IP from dhcp server.
2) dhcp server also sends to the new machine the name of a file and the 
location to download it from.
       (aka. the name of the PXE boot file and the name/IP of the tftp 
server.)
3) The PXE image will then download a config file.
         (In my case it's for kickstart. This can be retrieved via http.)

The dhcp server can customize the name of the PXE config file. But, if I 
want the format of the file to be driven by a database, then I need an 
"out-of-band" process to generate those files.

I would like the tftp server to be able to fork a process that will 
query a database and then return the appropriate "file".

The out-of-band process isn't a *horrible* way to do it.... but, if the 
tftp server could fork a process (ala CGI in http), then the process 
would be cleaner.

TIA!
Craig

Craig wrote:
> Hi.
> 
> Has there ever been any consideration to allowing the tftp server to 
> provide dynamic content?
> 
Yes.  The protocol makes it difficult.

You pretty much have to guarantee that the contents is generated in a 
fraction of a second, or your client will most likely flood your server.

The problem is that in order to be able to answer a tsize query you have 
to know the full size of the output.  However, since TFTP isn't 
guaranteed to distinguish between an RRQ resend and a new request 
(pxelinux will make the distinction, but it's hard for the TFTP server 
to make use of it), so you have to have a reply before the first request.

I have a proposal for a TFTP "pause" option and opcode, but I would
have
to (a) implement it, and (b) write it up as an RFC, (c) figure out how 
to get it through IETF, which like to pretend TFTP doesn't exist.

	-hpa