Improve the `Socks5` proxy

[rustaceanrob]

Describe the enhancement

Socks5 protocol allows for username and password credentials, but these cannot currently be set. In the future, once bitcoin_hashes has a release, Socks5 also supports connecting to a domain, which may be submitted as an onion address.

Use case

Adding credentials to the Tor proxy might make it more secure, moreover, their are many nodes behind Tor addresses.

[alfred-hodler]

Just curious, what issues are you facing with SOCKS?

In peerlink, I am using the socks library which is battle tested. It supports domain resolution fine, which is a prerequisite for working with onion services.

At least with Tor, the idea behind proxy credentials isn't security but circuit isolation: every time you connect to the proxy with different credentials, Tor will issue you a new circuit (see IsolateSOCKSAuth which is on by default).

[rustaceanrob]

The issue could be more descriptive, and perhaps this doesn't have much to do with Socks5. When Tor nodes are gossiped over the network they are advertised by ED25519 public key, whereas the Socks5 proxy requires a domain. To go from public key to onion address, a SHA3-256 hash of the public key used to compute a checksum, which is not yet available in bitcoin_hashes, although it has been merged to master. If you are curious here is the list of steps.

As far as authentication, I wasn't entirely sure what the use of username/password was, so thanks for the clarification. I would consider that more of a nice-to-have.

[alfred-hodler]

I hand rolled the pubkey -> domain conversion, there's not much to it and you probably don't need a dependency. Feel free to take it from here.

[rustaceanrob]

Great, thanks for the reference