Add support for downloading via bittorrent

[echawk]

Given the culture of KISS linux, and the restrictions of the total amount of data that we can host, I think it would be smart to add support for making torrent downloads of each of the packages.

The two biggest issues would be having a torrent client in rust, and something to produce torrent files.

Granted, I have not done much programming in rust, but I was able to find a couple of libraries that look like they would allow us to implement this functionality:

• https://github.com/ikatson/rqbit - torrent client to run on the server and serve as the initial seed
• https://github.com/casey/intermodal - creating the .torrent files

End users would only need to have aria2c installed, perhaps support for other clients could be supported in the future, but aria2c already has upstream support in KISS.

Thoughts?

[kiedtl]

(For some reason github didn't notify me of this, sorry for the late reply)

I like this idea, but the main issue is that I want to completely decouple storage from the server -- all tarballs should be handled only by the Backblaze B2 storage. This is currently accomplished by passing signed readonly URLs to downloaders, and providing signed read-write URLs for uploaders. The server doesn't even directly scan the tarball to list its contents, size, etc -- everything is done by querying B2 via its S3 api.

Why? To save network and computing power. My resources to spend on this project are very limited, and I'm just using the absolute cheapest plan I could find -- 2 GB RAM, 1 CPU core. OVH is generous with network limitations (I have a hard time figuring out the exact terms of my plan, but from what I understand, it's basically unlimited except for extreme cases). Storage is also an issue -- I'm no torrent expert, but for a torrent server to be running, the tarballs would have to be stored on the server itself, no?

S3 used(?) to have a torrent API, but unfortunately it looks like B2 doesn't.

I'll keep this issue open for now.