peer downloading same data over and over

[geezer]

I had a very small torrent (4.63 Meg) set to seed for X hours and much to my surprise I discovered that one of the peers had downloaded 16 times (77.9 Meg) the size of the torrent from me. According to the tracker, there were a total of 16 seeds so I was presumably not the only seed he was downloading from.

I can think of two possibilites:

1. a bug in the user's client, a bug in the user's router, or an anti-BT kludge at the user's ISP was causing the client to get checksum errors and the client didn't have auto-banning so it just kept downloading the same pieces over and over and over.

2. the client was hacked to do this deliberately (a prank).

Note this torrent was for a "legal" file, hosted on the publisher's own tracker. This is not a torrent that the RIAA or MPAA would be interested in messing with. But some dork could be.

Either way, would it be possible to modify µTorrent to detect that a client is requesting the same data over and over? It could maintain a per-peer array of counters for each piece in the torrent. Each time a peer requests a block of a piece, increment that peer's counter for that piece. If the peer requests too many blocks from the same piece, ban the IP (until µTorrent is restarted or whatever).

Even if I set all my torrents to stop after X% rather than X hours, a single "runaway" peer like this can waste all the bandwidth that would otherwise have gone to upload to well-behaved peers.

[boo]

or the it's a company/community/university that only has one external ip.