Everything there looks very pro HTTP like... But hey, curl doesn't support bittorrent afaik. So why should haxx.se care ;-)
Interesting link in that Wikipedia article [1] to Apple's LEDBAT implementation used for downloading updates.
[1] https://opensource.apple.com/source/xnu/xnu-1699.32.7/bsd/ne...
uTP is a very nice bittorrent over UDP protocol implementing LEDBAT congestion control algorithm [1].
1 - https://en.m.wikipedia.org/wiki/LEDBAT