Make RPC request limit configurable

[jochem-brouwer]

The current limit of the JSON-RPC service (for both RPCs like eth and engine) is currently hardcoded at 11MB

ethereumjs-monorepo/packages/client/src/util/rpc.ts

Lines 191 to 192 in 79155fe

	app.use(JSONParser({ limit: '11mb' }))

For JSON-RPC eth this seems wayyy too high. For engine, this could be too low, especially if these are full blocks with blobs in them (and also since the max blobs in Prague is now 9, not 6 (Cancun)). We should raise this limit on the engine JSON-RPC service since this service is trusted and authenticated.

Additionally, we should add CLI flags to edit the limits of the trusted service (engine) and the non-trusted service (eth/debug/whatever, anything which is not engine)

[ether-wan]

Gm @jochem-brouwer can I work on this issue?

[ether-wan]

Here is the approach I would like to propose:

The idea would be to add two new parameters in the configuration file: rpcEngineMaxPayload and rpcEthMaxPayload, which would be customizable if the user provides specific CLI arguments.

• In the case where the eth and the engine rpc are started on the same address and port (a single server for both services), we would apply a common payload size limit for both.

• In the case where the eth and engine rpc are started on separate addresses and ports (two distinct servers), we would be able to apply different payload size limits for each service.

Another option could be to enforce that eth and engine rpc must always run on separate servers, but this would introduce a breaking change compared to the current setup.

[jochem-brouwer]

Hey @ether-wan, sorry I wanted to reply to this yesterday but I forgot! This is a good issue to start on and your approach looks good to me!

I am only not sure if we are running both engine and eth on the same address+port, I think this should be by default the localhost:8545 (eth) and localhost:8546 (engine).

[jochem-brouwer]

Just assigned you, feel free to move ahead with this and let us know if you run in any problems or have a question. If you prefer chat, we have a discord https://discord.gg/TNwARpR 😄 👍

[ether-wan]

Hey @ether-wan, sorry I wanted to reply to this yesterday but I forgot! This is a good issue to start on and your approach looks good to me!

I am only not sure if we are running both engine and eth on the same address+port, I think this should be by default the localhost:8545 (eth) and localhost:8546 (engine).

Yes, you're right! I've just realised that by default, two servers are created: one on port :8545 for eth and one on port :8551 for engine.

That's great because it simplifies setting different maximum payload sizes for each server 😁

[jochem-brouwer]

Ah right good point I confused the ports, it's indeed 8551 for the engine (8546 for websocket JSON-RPC)