[syslinux] Dialog Menu System ?

H. Peter Anvin hpa at zytor.com
Tue Nov 14 14:22:34 PST 2006


Darryl Miles wrote:
> 
> Would you care to elaborate on "to be necessary to make a modification 
> to the TFTP protocol" part ?
> 

Yes, what's needed is a new opcode in the TFTP protocol that says "I 
heard you, but please wait for the next packet."  The reason for that is 
that there is no way for the server to distinguish between a resend of 
an RRQ due to timeout, and a new request.  In order for the tsize option 
to work, the "CGI" application needs to finish executing before 
transmission begins.  If the application is slow, the client might time 
out, re-send the RRQ, and spawn another application instance.  This 
quickly leads to avalanche failure.

This is a fairly trivial extension to the protocol, and can be handled 
via the options negotiation mechanism.

> The basic TFTP protocol allows for a GET and PUT file operation.  My 
> vision of how it might work uses those operations if the file name is 
> earmarked at the server as a CGI the server sends data to the executable 
> or reads data from the executable.  A basic pipe mechanism would do the 
> trick, otherwise a run executable using a temporary file.
> 
> Simple is good.

In the words of Einstein, make it "as simple as possible, but no simpler."

	-hpa




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