LayerzeroImplementation

Introduction

This contract is used to allow Superform to send messages via LayerZero.

Core Concepts

LayerzeroImplementation builds upon AMBImplementation to formalize certain methods specific to LayerZero. The application is notably nonblocking, to ensure that Superform's destination LayerZero Endpoint will never be blocked. You can read more on nonblocking applications here.

Trusted Remotes

Trusted remotes establish a secure connection between the LayerzeroImplementation on source chain and the LayerzeroImplementation on destination chain. They are configured by the LayerzeroImplementation contract on the LZendpoint which validates it upon sending and receiving payloads. You can read more on Trusted Remotes here.

Receiving payloads

LayerZero attempts to call lzReceive function on Superform's LayerzeroImplementation contract after the successful validation of a message at the bridge end. Upon delivery, certain mandatory input validations are made by the lzReceive function.

lzReceive

Receives a payload from the LayerZero endpoint and forwards it to the appropriate state registry by decoding the payload header. The lzReceive function can only be called by the LayerZero endpoint and each nonce_ can only be used once.

function lzReceive(
        uint16 srcChainId_,
        bytes memory srcAddress_,
        uint64 nonce_,
        bytes memory payload_
) public;

name	description
srcChainId_	uint16 identifier of the chain from which the cross-chain message is sent
srcAddress_	trusted remote that sent the message
nonce_	unique identifier used to prevent replay attacks used by the message bridge
payload_	the cross-chain message send by the srcAddress_ from srcChainId_

Retrying Payloads

As mentioned in the AMB Implementations section, messages can be retried by calling retryPayload with a bytes hash of relevant data. In the case of LayerZero, the data is the following:

(uint16 srcChainId, bytes memory srcAddress, bytes memory payload)

Configuration Setters

There are multiple bridge related configurations to be made on the LayerzeroImplementation contract. These configuration functions are gate kept and can only be called by addresses with PROTOCOL_ADMIN_ROLE

setChainId

Each messaging bridge uses their own chain identifiers, different than the blockchain's native chain identifier (a uint256 value). Hence a mapping is introduced to map the chain id of the bridge to Superform protocol's internal chain ids.

function setChainId(uint64 superChainId_, uint16 ambChainId_) external

name	description
superChainId_	internal chain id used by the Superform protocol. block.chainid casted to uint64
ambChainId_	uint16 chain id allocated to each chain by LayerZero

setLzEndpoint

This setter function updates / sets the LayerZero endpoint contract. The LayerZero endpoint is where cross-chain messages are sent/received by LayerzeroImplementation

function setLzEndpoint(address endpoint_) external

name	description
endpoint_	the address of the LayerZero's endpoint contract

setConfig

function setConfig(
    uint16 version_,
    uint16 chainId_,
    uint256 configType_,
    bytes calldata config_
) external override onlyProtocolAdmin

name	description
version_	uint16 version of the configuration
chainId_	uint16 LayerZero chainId to update
configType_	uint256 type of configuration
config_	bytes config data to set