[bridge] Replay protection on L1

[apenzk]

Problem

This considers a transfer from L2 --> L1.

The relayer may (maliciously or by accident) complete a transfer on the target chain (L1) twice. This needs to be prevented, as it constitutes a double spend.

Background

MIP-58: Trusted-Relayer focused Bridge Design

Solution

Transfers are identified on the source chain (L2) by L2L1bridgeTransferId. The native bridge contract on the target chain (L1) MUST keep a list L2L1bridgeTransferIds in the solidity contract and the contract MUST check if the requested completion of a transfer by the relayer has been already previously completed.

Recommendations

DO NOT use bridgeTransferId. It should be crystal clear from the code that this is an L2-->L1 transfer.

[Primata]

// Ensure the nonce is valid
        require(nonce > 0, InvalidNonce());

        // Ensure the incoming bridge transfer ID has not already been completed
        require(idsToIncomingNonces[bridgeTransferId] == 0, CompletedBridgeTransferId());
        // Ensure the bridge transfer ID is valid against the initiator, recipient, amount, and nonce
        require(
            bridgeTransferId == keccak256(abi.encodePacked(initiator, recipient, amount, nonce)),
            InvalidBridgeTransferId()
        );

        // Store the incoming nonce to incoming bridge transfer ID
        idsToIncomingNonces[bridgeTransferId] = nonce;
        ```
        
        does this suffices?