[BitTorrent] Re: Request for protocol extension: get_info/info messages

Iain Wade iwade at optusnet.com.au
Mon Jan 17 00:23:01 EST 2005


Hi Bill.

> I think it's worth adding simple extensions to help keep the ISPs happy.
> The cache look-up is a little scary, but it could be an option that
> users could turn off.  I know I'd keep that option on.

Fantastic :-)

> The get_info/info is a fairly simple handshake, though I don't like it's
> having such a large load.  I'd prefer an incremental mechanism like the
> piece_info/piece_correct handshake.  Anyone benefiting from the cache-
> lookup extension would probably also support the related extension in
> the peer protocol, so someone would be there to help authenticate pieces
> as long as there was anyone interested in downloading from your cache.

OK.

Some other pieces of information needed are total size and piece size.
If the cache needs this information from a client, how can it verify
the accuracy of that information? In the get_info solution they are a
validated portion of the info blob.

Let me ask, if I were to implement something along these lines (with a
significantly larger patch) would people be more accepting? Bram?

> Would this be a good point to introduce Merkle hash trees, or should we
> wait for BT2?  The idea is that the get_info/info handshake would return
> a Merkle hash root for the torrent, rather than the whole info blob.  It
> would be a tiny message.  Then, we'd have a get_authentication_path /
> authentication_path handshake to authenticate the piece data.  Only path
> data up to a requested level in the tree would be returned.

I'm interested, but have no exposure to these algorithms. I guess for
them to be usefull I would still like to see them in a validated info
blob payload and that would require all clients to be updated.. BT2
perhaps.

Thanks for your views.
--Iain


 
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