Remove dead bootnodes, add new geth bootnodes

[dvdplm]

This PR removes all the bootnodes that do not respond to connection attempts with telnet <ip address> <port>. This leaves us with the 4 parity bootnodes plus the "new" geth bootnodes (as per holiman/go-ethereum@a4eeeed) and removes all legacy nodes that I (we?) do not know the exact status of.

There's a discussion to be had about using JSON as a config file format (in short: it's a terrible idea), but this PR is not the place for that.

Questions to reviewers: what is a better way to test if a bootnode is up? And if it's down, what's a reasonable course of action to figure out if it's temporary or permanent? Is "telnet them for a few days" the best we can do?

[varasev]

what is a better way to test if a bootnode is up?

BTW, we used nc -vz [host] [port] to test our POA bootnodes.

[niklasad1]

BTW, we used nc -vz [host] [port] to test our POA bootnodes.

Sounds good to run in the CI (maybe once per week) by reading the enodes of the chainspec or just extract a CLI tool from devp2p to try send a Hello message instead of just the ip address

There's a discussion to be had about using JSON as a config file format (in short: it's a terrible idea), but this PR is not the place for that.

+1

EDIT: As long as we have these in the chainspecs we should incorporate these checks in the chainspec binary

[niklasad1]

Tested with a modified version chainspec bin

fn quit(s: &str) -> ! {
	println!("{}", s);
	process::exit(1);
}

fn main() {
	let mut args = env::args();
	if args.len() != 2 {
		quit("You need to specify chainspec.json\n\
		\n\
		./chainspec <chainspec.json>");
	}

	let path = args.nth(1).expect("args.len() == 2; qed");
	let file = match fs::File::open(&path) {
		Ok(file) => file,
		Err(_) => quit(&format!("{} could not be opened", path)),
	};

	let spec: Result<Spec, _> = serde_json::from_reader(file);

	let spec = match spec {
		Ok(spec) => spec,
		Err(err) => quit(&format!("{} {}", path, err.to_string())),
	};


	for node in spec.nodes.unwrap().iter() {
		let s: Vec<_> = node.split("@").collect();
		let sock_addr: SocketAddr = s[1].parse().expect("valid ip address");
		println!("testing node: {}", sock_addr);
		let stream = TcpStream::connect_timeout(&sock_addr, Duration::from_secs(30)).expect("node is down");
	}

	println!("{} is valid", path);
}