Don't proxy or log malformed requests

[hansr]

This PR just returns 400/failure to malformed requests (nil in chain_id or epoch) without a) logging as error (caught in code before exception handler) or b) sending the malformed request as a proxy.

This should at least remove the "error" from the logs - people are posting about this because they feel this is a problem with their node. It should also reduce network traffic somewhat because if the request was bogus we don't pass it along.

Minor, but real time potential improvement. No time urgency.

[gemini-code-assist]

Summary of Changes

Hello @hansr, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces robust error handling for malformed RPC requests, specifically targeting cases where essential parameters like 'chain_id' or 'epoch' are invalid or missing. By returning a 400 Bad Request response immediately, the system avoids unnecessary error logging and prevents these requests from being proxied, thereby improving system stability, reducing log clutter, and optimizing network resource usage.

Highlights

• Malformed Request Handling: Implements immediate rejection of malformed RPC requests with a 400 status.
• Reduced Logging: Prevents malformed requests from being logged as errors, significantly reducing log noise.
• Optimized Network Traffic: Avoids proxying bogus requests, thereby conserving network resources.
• Parameter Validation: Adds explicit checks for 'nil' or missing 'chain_id' and 'epoch' parameters in 'dio_traffic' and 'dio_tickets' RPC calls.

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[gemini-code-assist]

Code Review

This pull request effectively addresses the issue of malformed requests by adding validation to prevent them from being proxied or logged as errors. The changes for dio_traffic and dio_tickets RPC methods are sound. I've included a few suggestions to improve code clarity, reduce duplication, and make the new logic more concise and maintainable.

[gemini-code-assist]

This logic for extracting chain_id_param is duplicated in the dio_tickets handler (lines 313-318). To improve code reuse and maintainability, consider extracting this logic into a private function. For example:

defp get_chain_id_param(params) do
  case params do
    [] -> throw(:badrequest)
    [nil | _] -> throw(:badrequest)
    [param | _] -> param
  end
end

You could then call get_chain_id_param(params) in both places.

        chain_id_param = get_chain_id_param(params)

[gemini-code-assist]

The last two clauses in this case statement produce the same result. They can be combined into a single, more concise clause using a tail match.

          case params do
            [_chain_id, epoch] when epoch != nil -> Base16.decode_int(epoch)
            [_chain_id | _] -> peak_epoch
          end

[gemini-code-assist]

Similar to the dio_traffic handler, the last two clauses in this case statement can be combined into a single clause for conciseness.

          case params do
            [_chain_id, epoch] when is_integer(epoch) -> epoch
            [_chain_id, epoch] when is_binary(epoch) -> Base16.decode_int(epoch)
            [_chain_id | _] -> peak_epoch
          end

[gemini-code-assist]

The logic to check for invalid parameters can be simplified. The params != [] check is redundant because [nil | _] will not match an empty list. You can use match?/2 for a more concise boolean check.

        invalid_params =
          method in ["dio_traffic", "dio_tickets"] and
            match?([nil | _], params)