[bittorrent] Protocol Deviation in Mainline

Ludvig Strigeus strigeus at gmail.com
Thu Mar 2 03:31:38 EST 2006

µTorrent used to default to 32kb pieces. In some early version, I
noticed that mainline peers were disconnected all the time, so I
switched default to 16k.

On 3/2/06, Olaf van der Spek <olafvdspek at gmail.com> wrote:
> 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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