gasp
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GASP stands for 'Generator and Analyzer System for Protocols'. It allows you to decode and encode any protocols you specify.

The main use is probably to test networks applications : you can construct packets by hand and test the behavior of your program when facing some strange packets. But you can image a lot of other application : e.g. manipulating graphical file or executable headers. Just describe the specification of the structured data.

GASP is divided in two parts : a compiler which take the specification of the protocols and generate the code to handle it, this code is a new Tcl command as GASP in build upon Tcl/Tk and extends the scripting facilities provided by Tcl.

Enough words, let's see how all this works. Let image you're working on a TCP/IP packet. To dump the IP header and change some values, it is quite simple :

% pkt ip configure
-version 4 -headerlength 5 -tos {routine {-delay -throughput -reliability -res1 -res2}}
-length 69 -identification 12345 -flags {-res -df -mf} -fragoffset 0 -ttl 10
-protocol tcp -checksum 27768 -src 10.0.0.1 -dest 10.0.0.2 -options {}
% pkt ip configure -dest 10.0.0.3 -flags +df
%

    
   

Copyright © 2000 Laurent Riesterer.
Last modified on Mar 2, 2000.