feat: Tor/SOCKS5 proxy support: add optional proxyInfo property and use it (via the socks5_proxy package) if not null.

[sneurlax]

Closes #1377.

Adds an optional proxyInfo property to a Solana RpcClient. If it's null (as old clients will pass it by default), it changes no behavior. If it's not null, it uses the provided proxyInfo to proxy requests. Pass proxyInfo as a Map<String, dynamic> {String host, int port}.

Dart 3 supports Records, in which case proxyInfo could be ({String host, int port})? proxyInfo.

Changes

• Add the socks5_proxy package. This is widely used and used by Stack Wallet.

Related issues

Fixes #1377

Checklist

• PR is ready for review (if not, it should be a draft).
• PR title follows Conventional Commits guidelines.
• Screenshots/video not applicable.
• Tests unaffected.
• Self-review done.

[ookami-kb]

I don't think that adding another 3rd-party library for such a specific use case makes sense.

I would rather suggest making JsonRpcClient._postRequest method protected, and adding

factory RpcClient.withCustomClient(JsonRpcClient client) {}

In that case, you can implement your custom behavior by extending JsonRpcClient class and passing it to the RpcClient factory.

[sneurlax]

I am currently testing the changes @ookami-kb requested, should I just open a new PR @antoineherzog?

[ookami-kb]

@sneurlax feel free to either reopen this one or create a new one - whatever is more convenient for you.

[sneurlax]

There have been a series of issues implementing it as recommended. The only solution I've got working as requested is very long because it has to implement overrides for every method in JsonRpcClient. I really tried to minimize the diff and avoid these overrides, but the most elegant solution requires use of dart:mirrors in order to get the expected return types of methods, which is not possible because out app is Dart 3, not the outdated Dart 2 which this package uses. Dynamic return types and delegating methods in the custom RPC client using noSuchMethod might be a shorter solution, but I could not ultimately get that approach working in Dart 3.

I would almost be content to say "Stack Wallet is the only Dart/Flutter wallet to support Tor for Solana" rather than continue working on minimizing the changes necessary to get it working as requested. We're currently simply using our cypherstack/espresso-cash-public fork to accomplish this currently using the code originally submitted as-is--not using the changes as requested (although I tested them working). I don't like using an unmaintained fork, though, hence my attempt at fulfilling the requested code change.

@ookami-kb can you consider simply accepting the original patch? socks5_proxy is one of the most widely used SOCKS packages and is Dart 2 and 3 compatible. It would minimize the diff required for your Dart/Flutter users to have any option for proxy use. Otherwise, the changes required to get it working are as shown on my subsequent PR (I can't reopen this one).

[sneurlax]

update: as I have been testing more functions, I have been finding more issues. I don't have enough Solana to test all functions and I really, really don't like this solution anyways. See 1,000+ lines of biolerplate at: https://github.com/cypherstack/espresso-cash-public/blob/test/packages/solana/lib/src/rpc/custom_client.dart

@ookami-kb, what am I doing wrong? You made this approach sound easy and simple, but it has been anything but easy and simple for me over here.