The core functionality of the feature takes place at
`packages/relayer/src/services/privacyPoolRelayer.service.ts` in the
`validateWithdrawal` function. There we check in order:
1. Decode Withdrawal.data and check feeReceiver ==
CONFIGURED_FEE_RECEIVER && feeBPS == CONFIGURED_FEE_BPS
2. Hash (Withdrawal || Scope) and check hash == Proof.context
3. Verify proof with SDK.verifyProof(Proof)
4. Call Entrypoint.scopeToPool() to get asset pool
5. Call Pool.ASSET() to get withdrawn asset
6. Check proof.withdrawnAmount() >=
CONFIGURED_MINIMUM_AMOUNT[withdrawn_asset]
If everything is ok, we call the Entrypoint.relay() with the user's
proof.
I've added examples for the config files `env.example`,
`withdraw_amount.example.json`. The first one are environment variables
to be defined in the server's environment. The second one contains a
mapping of the mimimum withdraw limits for the different supported
assets. There's an env var that should contain a path to this file.
Added a `Dockerfile` and a `docker-compose.yml` to the relayer to test
it or use it in dev flows. The circuit artifacts are loaded as volumes,
so before starting the docker-compose, you should run `yarn present`
from the circuits package dir to group all the artifacts and make them
easily accesible.
Additionally added a small package in
`/packages/relayer/test/integration/relay` that can be built and run to
test the relayer.
There are a lot of TODOs related to code quality, mostly happy path
assumptions, input sanitization, error handling and tests. Feature wise
it's missing the contract interaction (should be straight forward once
it's implemented in the SDK) and the sqlite database for request
tracking.
