CrossChainRouter

Overview

CrossChainRouter enables branded stablecoins to be transferred across supported EVM chains using the Frax LayerZero mesh. It coordinates the redemption of branded tokens to frxUSD on the source chain, bridges frxUSD via LayerZero, and re-mints branded tokens on the destination chain.

Key Features

• Cross-chain branded stablecoin transfers via LayerZero OFT
• Simple quote / send interface for easy integration
• LZ OFT-compatible quoteSend / send interface for advanced use
• Compose-based minting on destination chains via hopCompose
• Support for non-deterministic router addresses across chains

Initialization

function initialize(
  address _owner,
  address _custodianAddress,
  address _coin,
  address _localFrxUSD,
  address _localRemoteHop,
  bool _isolatedBackingEnabled
) external

• Called once by the BrandedFactory upon deployment.
• Sets up the custodian, branded token, frxUSD OFT, and RemoteHopV2 references.

Constants

State Variables

Functions

Simple Interface

function quote(uint32 dstEid, address recipient, uint256 amount) public view returns (uint256)

• Returns the native gas fee required for a cross-chain transfer.

function send(uint32 dstEid, address recipient, uint256 amount) public payable

• Transfers branded tokens cross-chain.
• Caller must approve the router to spend branded tokens first.
• The router redeems tokens for frxUSD via the custodian, then sends frxUSD cross-chain via LayerZero.
• On the destination chain, hopCompose is triggered to mint branded tokens to the recipient.
• Excess msg.value is refunded to the caller.

LZ OFT-Compatible Interface

function quoteSend(SendParam calldata _sendParam, bool _payInLzToken) external view returns (MessagingFee memory)

• Returns the messaging fee for a cross-chain send using the LZ SendParam struct.
• _payInLzToken must be false.
• composeMsg and oftCmd must be empty.
• to must have leading 12 bytes as zero (EVM address).

function send(
  SendParam calldata _sendParam,
  MessagingFee calldata _fee,
  address _refundAddress
) external payable returns (MessagingReceipt memory, OFTReceipt memory)

• Cross-chain send using the LZ-compatible interface.
• _refundAddress must be msg.sender.
• lzTokenFee must be 0.

Compose Hook

function hopCompose(uint32 srcEid, bytes32 sender, address oft, uint256 _amount, bytes memory data) external

• Called by RemoteHopV2 when frxUSD arrives on the destination chain.
• Deposits frxUSD into the custodian, minting branded tokens to the encoded recipient.
• Only callable by the RemoteHopV2 contract.

Mint and Send

function mintAndSend(uint32 dstEid, address recipient, uint256 amount) external payable returns (uint256 out)

• Accepts frxUSD directly, bridges it cross-chain via LayerZero.
• Not available when isolatedBackingEnabled is true.

Admin Functions

function setNonDeterministicRouterAddress(uint32 eid, bytes32 value) external onlyRole(RELAYER_ROLE)
function setHopV2Address(address _updatedAddress) external onlyRole(DEFAULT_ADMIN_ROLE)

Custom Errors

Events

Author: Frax Finance License: AGPL-3.0-only