Building a BitTorrent client from the ground up in Go

Over the holidays, I challenged myself to learn Go by torrenting the Debian ISO -- from scratch. This post is a bit of a brain dump about everything I've learned over the past week.

Thanks, this is really cool. I don't have anything to add; I just want to let the author know this is appreciated. I recently decided to learn Go, and articles like this are a great way to get a feel for how Go programmers think about solving problems with the tools available to them. The kind of knowledge you don't get from just skimming The Go Programming Language and such.

It is easy to make a torrent client, but very hard to make a good torrent client. A very good, or let's say "perfect", one, needs to support multiple transport protocols (TCP, "uTP" aka UDP, "WebTorrent" aka WebRTC), multiple discovery mechanisms (DHT, PEX, HTTP trackers, WebSocket trackers), multiple torrent formats (v1, v2, hybrid), should use the network optimally (max the speed without overloading the network - IIRC some clients measure average packet latency and if it starts going up, put…