// SPDX-License-Identifier: MIT OR Apache-2.0 pragma solidity >=0.6.11; // ============ Internal Imports ============ import {TokenRegistry} from "./TokenRegistry.sol"; import {Router} from "../Router.sol"; import {IBridgeToken} from "../../interfaces/bridge/IBridgeToken.sol"; import {BridgeMessage} from "./BridgeMessage.sol"; // ============ External Imports ============ import {Home} from "@celo-org/optics-sol/contracts/Home.sol"; import {TypeCasts} from "@celo-org/optics-sol/contracts/XAppConnectionManager.sol"; import {TypedMemView} from "@summa-tx/memview-sol/contracts/TypedMemView.sol"; import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol"; import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/SafeERC20.sol"; import {Initializable} from "@openzeppelin/contracts/proxy/Initializable.sol"; /** * @title BridgeRouter */ contract BridgeRouter is Initializable, Router, TokenRegistry { using TypedMemView for bytes; using TypedMemView for bytes29; using BridgeMessage for bytes29; using SafeERC20 for IERC20; /// @notice 5 bps (0.05%) hardcoded fee. Can be changed by contract upgrade uint256 public constant PRE_FILL_FEE_NUMERATOR = 9995; uint256 public constant PRE_FILL_FEE_DENOMINATOR = 10000; /// @notice A mapping that stores the LP that pre-filled a token transfer /// message mapping(bytes32 => address) public liquidityProvider; // ======== External: Handle ========= /** * @notice Handles an incoming message * @param _origin The origin domain * @param _sender The sender address * @param _message The message */ function handle( uint32 _origin, bytes32 _sender, bytes memory _message ) external override onlyReplica onlyRemoteRouter(_origin, _sender) { // parse tokenId and action from message bytes29 _msg = _message.ref(0).mustBeMessage(); bytes29 _tokenId = _msg.tokenId(); bytes29 _action = _msg.action(); // handle message based on the intended action if (_action.isTransfer()) { _handleTransfer(_tokenId, _action); } else if (_action.isDetails()) { _handleDetails(_tokenId, _action); } else { require(false, "!valid action"); } } // ======== External: Send Token ========= /** * @notice Send tokens to a recipient on a remote chain * @param _token The token address * @param _amnt The amount * @param _destination The destination domain * @param _recipient The recipient address */ function send( address _token, uint256 _amnt, uint32 _destination, bytes32 _recipient ) external { // get remote BridgeRouter address; revert if not found bytes32 _remote = _mustHaveRemote(_destination); // remove tokens from circulation on this chain IERC20 _bridgeToken = IERC20(_token); if (_isLocalOrigin(_bridgeToken)) { // if the token originates on this chain, hold the tokens in escrow // in the Router _bridgeToken.safeTransferFrom(msg.sender, address(this), _amnt); } else { // if the token originates on a remote chain, burn the // representation tokens on this chain _downcast(_bridgeToken).burn(msg.sender, _amnt); } // format Transfer Tokens action bytes29 _action = BridgeMessage.formatTransfer(_recipient, _amnt); // send message to remote chain via Optics Home(xAppConnectionManager.home()).enqueue( _destination, _remote, BridgeMessage.formatMessage(_formatTokenId(_token), _action) ); } // ======== External: Fast Liquidity ========= /** * @notice Allows a liquidity provider to give an * end user fast liquidity by pre-filling an * incoming transfer message. * Transfers tokens from the liquidity provider to the end recipient, minus the LP fee; * Records the liquidity provider, who receives * the full token amount when the transfer message is handled. * @param _message The incoming transfer message to pre-fill */ function preFill(bytes calldata _message) external { // parse tokenId and action from message bytes29 _msg = _message.ref(0).mustBeMessage(); bytes29 _tokenId = _msg.tokenId().mustBeTokenId(); bytes29 _action = _msg.action().mustBeTransfer(); // calculate prefill ID bytes32 _id = _preFillId(_tokenId, _action); // require that transfer has not already been pre-filled require(liquidityProvider[_id] == address(0), "!unfilled"); // record liquidity provider liquidityProvider[_id] = msg.sender; // transfer tokens from liquidity provider to token recipient IERC20 _token = _mustHaveToken(_tokenId); _token.safeTransferFrom( msg.sender, _action.evmRecipient(), _applyPreFillFee(_action.amnt()) ); } // ======== External: Update Token Details ========= /** * @notice Update the token metadata on another chain * @param _token The token address * @param _destination The destination domain */ // TODO: people can call this for nonsense non-ERC-20 tokens // name, symbol, decimals could be nonsense // remote chains will deploy a token contract based on this message function updateDetails(address _token, uint32 _destination) external { require(_isLocalOrigin(_token), "!local origin"); // get remote BridgeRouter address; revert if not found bytes32 _remote = _mustHaveRemote(_destination); // format Update Details message IBridgeToken _bridgeToken = IBridgeToken(_token); bytes29 _action = BridgeMessage.formatDetails( TypeCasts.coerceBytes32(_bridgeToken.name()), TypeCasts.coerceBytes32(_bridgeToken.symbol()), _bridgeToken.decimals() ); // send message to remote chain via Optics Home(xAppConnectionManager.home()).enqueue( _destination, _remote, BridgeMessage.formatMessage(_formatTokenId(_token), _action) ); } // ============ Internal: Send / UpdateDetails ============ /** * @notice Given a tokenAddress, format the tokenId * identifier for the message. * @param _token The token address * @param _tokenId The bytes-encoded tokenId */ function _formatTokenId(address _token) internal view returns (bytes29 _tokenId) { TokenId memory _tokId = _tokenIdFor(_token); _tokenId = BridgeMessage.formatTokenId(_tokId.domain, _tokId.id); } // ============ Internal: Handle ============ /** * @notice Handles an incoming Transfer message. * * If the token is of local origin, the amount is sent from escrow. * Otherwise, a representation token is minted. * * @param _tokenId The token ID * @param _action The action */ function _handleTransfer(bytes29 _tokenId, bytes29 _action) internal typeAssert(_tokenId, BridgeMessage.Types.TokenId) typeAssert(_action, BridgeMessage.Types.Transfer) { // get the token contract for the given tokenId on this chain; // (if the token is of remote origin and there is // no existing representation token contract, the TokenRegistry will // deploy a new one) IERC20 _token = _ensureToken(_tokenId); address _recipient = _action.evmRecipient(); // If an LP has prefilled this token transfer, // send the tokens to the LP instead of the recipient bytes32 _id = _preFillId(_tokenId, _action); address _lp = liquidityProvider[_id]; if (_lp != address(0)) { _recipient = _lp; delete liquidityProvider[_id]; } // send the tokens into circulation on this chain if (_isLocalOrigin(_token)) { // if the token is of local origin, the tokens have been held in // escrow in this contract // while they have been circulating on remote chains; // transfer the tokens to the recipient _token.safeTransfer(_recipient, _action.amnt()); } else { // if the token is of remote origin, mint the tokens to the // recipient on this chain _downcast(_token).mint(_recipient, _action.amnt()); } } /** * @notice Handles an incoming Details message. * @param _tokenId The token ID * @param _action The action */ function _handleDetails(bytes29 _tokenId, bytes29 _action) internal typeAssert(_tokenId, BridgeMessage.Types.TokenId) typeAssert(_action, BridgeMessage.Types.Details) { // get the token contract deployed on this chain // revert if no token contract exists IERC20 _token = _mustHaveToken(_tokenId); // require that the token is of remote origin // (otherwise, the BridgeRouter did not deploy the token contract, // and therefore cannot update its metadata) require(!_isLocalOrigin(_token), "!remote origin"); // update the token metadata _downcast(_token).setDetails( TypeCasts.coerceString(_action.name()), TypeCasts.coerceString(_action.symbol()), _action.decimals() ); } // ============ Internal: Fast Liquidity ============ /** * @notice Calculate the token amount after * taking a 5 bps (0.05%) liquidity provider fee * @param _amnt The token amount before the fee is taken * @return _amtAfterFee The token amount after the fee is taken */ function _applyPreFillFee(uint256 _amnt) internal pure returns (uint256 _amtAfterFee) { _amtAfterFee = (_amnt * PRE_FILL_FEE_NUMERATOR) / PRE_FILL_FEE_DENOMINATOR; } /** * @notice get the prefillId used to identify * fast liquidity provision for incoming token send messages * @dev used to identify a token/transfer pair in the prefill LP mapping. * NOTE: This approach has a weakness: a user can receive >1 batch of tokens of * the same size, but only 1 will be eligible for fast liquidity. The * other may only be filled at regular speed. This is because the messages * will have identical `tokenId` and `action` fields. This seems fine, * tbqh. A delay of a few hours on a corner case is acceptable in v1. * @param _tokenId The token ID * @param _action The action */ function _preFillId(bytes29 _tokenId, bytes29 _action) internal view returns (bytes32) { bytes29[] memory _views = new bytes29[](2); _views[0] = _tokenId; _views[1] = _action; return TypedMemView.joinKeccak(_views); } }