[bittorrent] unforking

Justin Cormack justin at street-vision.com
Thu Mar 24 13:07:56 EST 2005


On Thu, 2005-03-24 at 09:46 -0800, Kenneth Porter wrote:
> --On Thursday, March 24, 2005 12:17 PM -0500 "David P. Mott" 
> <dpmott at sep.com> wrote:
> 
> > 1.  Agree that there's a new message, called CAPABILITIES.  It has a
> >      response.
> 
> Looking at the section on the peer handshake, it looks like the peer ID is 
> the only place where one could put something to identify whether a new 
> version of the protocol is supported without dropping the connection. It 
> doesn't look like any implementations use "CA" as a prefix so that could 
> indicate support for a capabilities command.

No thats not a good idea. The peer ID is supposed to be random, and
could have CA or anything else in.

There is space in the initial handshake, where you send 19 Bittorrent
Protocol 0 0 0 0 0 0. Problem is its not a very good namespace, and most
people are likely to disconnect if they get something they dont expect.

Its fine for a major upgrade.

For messages that you can cope (by fallback) with not getting a reply
to, I like the idea of default behaviour being to ignore them (though
you might charge the client for bandwidth if they continually spew
garbage at you...), just sending a nogrok message (nogrok then command
byte of command you got). Implicitly I read the standard as saying drop
in this situation. One of the many areas in which it is not clear.

Justin





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