BitComet Pollutes BitTorrent with Junk Data
Written by Ernesto on August 23, 2007Due to a new feature recently introduced into Bitcomet’s torrent maker, people who do not use BitComet (the majority) are sometimes forced to download so called “padding files” which is — for them — a waste of time and bandwidth.
So what are these padding files?
For every file in a multi-file torrent, BitComet includes a padding file by default. This overcomes the problem of ending one file and beginning another on the same BitTorrent “piece.” The feature was added to support finding sources from http/ftp/ed2k services on multi-file torrents.
For example, if BitComet users are downloading a set of .mp3 files, it tries to get some of those files from a non-BitTorrent source if possible. This is good both for the (BitComet) user and the swarm. However, the implementation of these padding files create problems for non-Bitcomet clients and the web sites that carry information from the *.torrent files.
Why is this a problem?
Unfortunately, BitComet’s development team sprung these padding files on to the rest of the community. If they had been more communicative, such as pre-publishing a specification, client makers and administrators of Torrent sites could then program their systems to mask them.
It impacts people who use uTorrent, Azureus or any other client than BitComet. The padding feature is enabled by default, so if a BitComet user created a .torrent, non BitComet users have to download these useless padding files. A padding file is created for every file in the .torrent, so if you download a collection of 100 MP3s you’ll be forced to download 100 (useless) padding files (see example). The average added overhead for an MP3 album will be around 3%, not too bad, but annoying because its junk data to most people. However, it is possible in rare circumstances that the amount of junk data caused by these files might exceed 10%.
The padding file feature might come to bite BitComet users. It has been reported that a malicious user could create a torrent with a fake padding file. This means that Bitcomet 0.85+ users will never be able to complete their downloads without switching to another client.
Some BitTorrent users are starting to get annoyed by these (for most people) useless padding files. “Fuzzier,” who has been leading the charge on several forums (including Wikipedia), sums it up:
“I and lots of my friends don’t use BitComet, and many others stick with older versions of BitComet. We see more and more useless padding files in torrents, and it gets really inconvenient — delete them then we cannot pass hash check and cannot seed; and no matter what, we get a bunch of wastes especially our precious upload bandwidth.”
Unless this practice becomes more widely adopted in the BitTorrent community, BitComet might consider disabling this feature by default, and suppling client makers and administrators of BitTorrent sites with the specs so they can decide how to deal with them.
Previously: BitTorrent Admin Monitored by US Government, Forced to Dump GNU/Linux
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54 Responses
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I justuse my client to kick and ban all the BitComet 0.85+ users polluting the network with their shit client.
ffs, the issue is not about disk space. It’s about bandwidth.
All of you Einstein posters sound like like a bunch of fucking-bitches,
Oh she colors her hair…Oh but she pads her bra…, and then the mob chimes in with amen and where do I sign up?
What’s really behind the anger??? I’ll bet one or two of you know the truth, and I’ll bet most of you can’t even write one line of code!
Don’t be a sucker to somebody else’s fight.
Padded bra as a simile!? Your contribution didn’t add anything. Get utorrent, might make you a happier person..
Bit Comet made these padding files an option to address the design flaw in selecting files within a torrent, when a single file spans more then one piece of data, making you download un needed parts of each piece.
There is no reason a user cannot simply download the torrent, then delete the padding files after the torrent is finished seeding.
Aug 24, 2007 at 17:23 by GrendelQuote Grendel
Why on Earth would anyone use an ad-supported client, anyway? There are plenty of free and open-source clients available. BitComet doesn’t offer anything that they don’t.
How about downloading http/ftp, edonkey, and combining all the above into a torrent download.
show me any client that has done that ever???
Sorry, on the above comment, I didn’t “quote” the other user correctly, and its a bit confusing to read.
I will think before I post next time lol
A better solution to the problem would be to use the SHA1 hash (or ed2k hash) keys common in many .torrent files responsibly.
They provide an alternate method of verifying files that cross piece boundaries. If the file fails SHA1 hashing, it is only likely because there was an error in the one piece that spanned two (or more) files. Just re-request that piece.
There is no need to fuck up bittorrent to solve problems about piece hashes that span files.
BitComet is, as usual, just being idiotic in its implementation.
> A padding file is created for every file in the .torrent,
> so if you download a collection of 100 MP3s you’ll be
> forced to download 100 (useless) padding files
Please stop murdering the English language like that — there is no “force(d)” involved here.
The word you are looking for is “required”.
The problem with these padding-files is that on has to download the contents of the file even if they deselect it, because that data is required for checking the hash of the piece. So it does cost bandwith.
(Unless you are using my client (which you aren’t ;) where you could ignore that hash-”fail”)
I am actually thinking I will add special “padding” files, to make use of the BitComet padding-file bug, as a feature, which is ON by default, to any created torrent :)
-BreezeBQB
Implementing simultaneous multi-protocol downloading couldn’t be done in any other way without breaking current BitTorrent protocol. Considering BitComet development strategy, including of this feature was inevitable. So, while waiting for other developers to do the same to their clients & trackers, users will have to care for themselves. In fact that’s easier than it seems.
These padding files always contain ‘nothing’ (hex 00’s), and their size is determined by the remainder of empty space in torrent’s corresponding pieces. Hence peer can manually reproduce such files in required amounts by copying/merging existing paddings or creating new ones in hex-editor. Note that there’s no need for them to be of empty spaces’ exact sizes - they can be longer. In this case user’s client (e.g. uTorrent) will crop them on next (manual) hash check.
Hence the best workaround is to keep a sufficient number of such pre-generated padding files in a handy place and copy them to the folder with BitComet 0.85+ torrent’s files. FAT32 users should consider placing paddings in zip/rar archive to save HDD free space; NTFS, on the other hand, won’t waste HDD space on empty files regardless of their size. Just make sure you stop your torrent before copying paddings; re-hash it after copying and you’re ready to leech real data instead of dummies…
thxzthxthxthx[quote comment="155752"]> A padding file is created for every file in the .torrent,
> so if you download a collection of 100 MP3s you’ll be
> forced to download 100 (useless) padding files
Please stop murdering the English language like that — there is no “force(d)” involved here.
The word you are looking for is “required”.[/quote]
[quote comment="152490"]Padded bra as a simile!? Your contribution didn’t add anything. Get utorrent, might make you a happier person..[/quote]
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I wonder if peerguardian includes ip’s of these bitcomet clients. Maybe the list woud get too big so just use utorrent and forget about crap like edonky and stuff.
bit comet it very suck with some chinese tracker
file 50mb with sob junk 1gb
delete them manually damnit … and there you go
So if i deselect these padding files in uTorrent, the download will still work?
@ Ya_Mum:
It will. However, your uTorrent will have to download them anyway to make hash check right; just you won’t see them on your HDD. If your torrent has a lot of padding files, swith to BitComet 0.85+ for it - this will save you some bandwidth, since only BitComet doesn’t download these empty padding files as of now.
using bitcomet was sucking.
got into utorrent and became an uploader using that magical torrent creating pad.
I wonder how people still have it and relentlessly claim it’s good.
亚森
[quote comment="151691"]asians love bitcomet.. i wonder why?[/quote]
You know who else loved bitcomet…
who else, dude? pls tell us.
btw, that, about asians,is something
known for thousands of years(it was some asians described in detail( in Plato’s Euthyphro) that led Socrates to the courts and finnaly death over stupid and, yes, religious accusations, not to mention the historic figure known as jesus christ), their history proves it, too,(certainly not what they get to read as history, though), and yep, it’s sad but let me quote once more:“The trouble with the world is that the stupid are cocksure and the intelligent are full of doubt”, Bertrand Russell, yeah.
I meant finally, yeah!
I hate those padding files.
Sorry, if you unselect those files, you’ll still need to download those. There is no way getting rid of that data.
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