Ethereal-users: Re: [Ethereal-users] tethereal performance questions

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From: Guy Harris <gharris@xxxxxxxxx>
Date: Wed, 19 Oct 2005 00:32:03 -0700
Joe Elliott wrote:

	My pipe example with tcpdump does not work with tethereal as the -r
switch to read a file does not handle STDIN. It works fine with tcpdump.

Can the developers put the '-r -' functionality in?

Not very conveniently. Tcpdump reads fewer types of capture files than does Tethereal; Tethereal's capture-file-reading library (the same one as Ethereal) determines the file type (and some other characteristics of the file) by trying to read the file multiple times. That's done by seeking back to the beginning of the file and reading; that doesn't work on pipes.

At some point the Ethereal/Tethereal library might do its own buffering, rather than using the "standard I/O library" routines, and might do its own uncompression, rather than using libz (libz doesn't, as far as I know, provide enough access to the decompresser's internal state to allow fast random access in compressed data streams). When that's done, the library will probably also support rewinding to the beginning of a pipe *IF* only one bufferful of data has been read (as there's no seeking to be done, just going back to the beginning of the buffer).

There's no schedule for doing that; it would depend on the free time available to developers (which is the case for just about every feature the user base might want).