[bittorrent] Protocol Deviation in Mainline

Olaf van der Spek olafvdspek at gmail.com
Thu Mar 2 03:06:34 EST 2006


On 3/2/06, Elliott Mitchell <ehem at m5p.com> wrote:
> The official specification continues to state:
>
>        "'request' messages contain an index, begin, and length. The last
>        two are byte offsets. Length is generally a power of two unless
>        it gets truncated by the end of the file. All current
>        implementations use 2^15, and close connections which request an
>        amount greater than 2^17."
>
> Sometime between 3.4 and 3.9 the mainline changed so that it would
> request 2^14 (16KB) and drop peers which requested more.
>
> This isn't the area I'd been looking at so I hadn't noticed until now
> (the pending fight on wiki.theory.org caused me to double-check). I'm
> surprised that no one has mentioned this on any of the lists. I'd guess
> either few folks use the mainline and therefor few are effected, most
> clients already used 16KB and therefore weren't effected, or everyone has
> been looking at the mainline code and copying that rather than the
> protocol specification.

I did notice (one of the users of my client) and I decreases chunk
size from 32 to 16 kbyte.
uTorrent copied mainline's behaviour and refused to argue about it.


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