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Router

A write-once deploy-everywhere pattern for interchain applications
Application developers looking to write their contracts once and deploy them on multiple chains should consider building with the Router pattern.
In this pattern, an instance of the application's contracts is deployed on each application-supported chain. Each instance is made aware of the addresses of instances on other chains. These instances use Hyperlane to communicate information and state to and from instances on remote chains.
Developers using this pattern can inherit from the Router mix-in contract. Router is a HyperlaneConnectionClient that tracks the addresses of other Router contract addresses on remote chains. This allows Routers to send messages directly to others without having to specify addresses. It also allows Routers to reject messages sent from other untrusted senders.
// SPDX-License-Identifier: MIT OR Apache-2.0
pragma solidity >=0.6.11;
// ============ Internal Imports ============
import {HyperlaneConnectionClient} from "./HyperlaneConnectionClient.sol";
import {IInterchainGasPaymaster} from "./interfaces/IInterchainGasPaymaster.sol";
import {IMessageRecipient} from "./interfaces/IMessageRecipient.sol";
import {IMailbox} from "./interfaces/IMailbox.sol";
import {EnumerableMapExtended} from "./libs/EnumerableMapExtended.sol";
abstract contract Router is HyperlaneConnectionClient, IMessageRecipient {
using EnumerableMapExtended for EnumerableMapExtended.UintToBytes32Map;
string private constant NO_ROUTER_ENROLLED_REVERT_MESSAGE =
"No router enrolled for domain. Did you specify the right domain ID?";
// ============ Mutable Storage ============
EnumerableMapExtended.UintToBytes32Map internal _routers;
uint256[49] private __GAP; // gap for upgrade safety
// ============ Events ============
/**
* @notice Emitted when a router is set.
* @param domain The domain of the new router
* @param router The address of the new router
*/
event RemoteRouterEnrolled(uint32 indexed domain, bytes32 router);
// ============ Modifiers ============
/**
* @notice Only accept messages from a remote Router contract
* @param _origin The domain the message is coming from
* @param _router The address the message is coming from
*/
modifier onlyRemoteRouter(uint32 _origin, bytes32 _router) {
require(
_isRemoteRouter(_origin, _router),
NO_ROUTER_ENROLLED_REVERT_MESSAGE
);
_;
}
// ======== Initializer =========
function __Router_initialize(address _mailbox) internal onlyInitializing {
__HyperlaneConnectionClient_initialize(_mailbox);
}
function __Router_initialize(
address _mailbox,
address _interchainGasPaymaster
) internal onlyInitializing {
__HyperlaneConnectionClient_initialize(
_mailbox,
_interchainGasPaymaster
);
}
function __Router_initialize(
address _mailbox,
address _interchainGasPaymaster,
address _interchainSecurityModule
) internal onlyInitializing {
__HyperlaneConnectionClient_initialize(
_mailbox,
_interchainGasPaymaster,
_interchainSecurityModule
);
}
// ============ External functions ============
function domains() external view returns (uint32[] memory) {
bytes32[] storage rawKeys = _routers.keys();
uint256 length = rawKeys.length;
uint32[] memory keys = new uint32[](length);
for (uint256 i = 0; i < length; i++) {
keys[i] = uint32(uint256(rawKeys[i]));
}
return keys;
}
function routers(uint32 _domain) public view returns (bytes32) {
if (_routers.contains(_domain)) {
return _routers.get(_domain);
} else {
return bytes32(0); // for backwards compatibility with storage mapping
}
}
/**
* @notice Register the address of a Router contract for the same Application on a remote chain
* @param _domain The domain of the remote Application Router
* @param _router The address of the remote Application Router
*/
function enrollRemoteRouter(uint32 _domain, bytes32 _router)
external
virtual
onlyOwner
{
_enrollRemoteRouter(_domain, _router);
}
/**
* @notice Batch version of `enrollRemoteRouter`
* @param _domains The domaisn of the remote Application Routers
* @param _addresses The addresses of the remote Application Routers
*/
function enrollRemoteRouters(
uint32[] calldata _domains,
bytes32[] calldata _addresses
) external virtual onlyOwner {
require(_domains.length == _addresses.length, "!length");
uint256 length = _domains.length;
for (uint256 i = 0; i < length; i += 1) {
_enrollRemoteRouter(_domains[i], _addresses[i]);
}
}
/**
* @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 calldata _message
) external virtual override onlyMailbox onlyRemoteRouter(_origin, _sender) {
_handle(_origin, _sender, _message);
}
// ============ Virtual functions ============
function _handle(
uint32 _origin,
bytes32 _sender,
bytes calldata _message
) internal virtual;
// ============ Internal functions ============
/**
* @notice Set the router for a given domain
* @param _domain The domain
* @param _address The new router
*/
function _enrollRemoteRouter(uint32 _domain, bytes32 _address) internal {
_routers.set(_domain, _address);
emit RemoteRouterEnrolled(_domain, _address);
}
/**
* @notice Return true if the given domain / router is the address of a remote Application Router
* @param _domain The domain of the potential remote Application Router
* @param _address The address of the potential remote Application Router
*/
function _isRemoteRouter(uint32 _domain, bytes32 _address)
internal
view
returns (bool)
{
return routers(_domain) == _address;
}
/**
* @notice Assert that the given domain has a Application Router registered and return its address
* @param _domain The domain of the chain for which to get the Application Router
* @return _router The address of the remote Application Router on _domain
*/
function _mustHaveRemoteRouter(uint32 _domain)
internal
view
returns (bytes32 _router)
{
_router = routers(_domain);
require(_router != bytes32(0), NO_ROUTER_ENROLLED_REVERT_MESSAGE);
}
/**
* @notice Dispatches a message to an enrolled router via the local router's Mailbox
* and pays for it to be relayed to the destination.
* @dev Reverts if there is no enrolled router for _destinationDomain.
* @param _destinationDomain The domain of the chain to which to send the message.
* @param _messageBody Raw bytes content of message.
* @param _gasAmount The amount of destination gas for the message that is requested via the InterchainGasPaymaster.
* @param _gasPayment The amount of native tokens to pay for the message to be relayed.
* @param _gasPaymentRefundAddress The address to refund any gas overpayment to.
*/
function _dispatchWithGas(
uint32 _destinationDomain,
bytes memory _messageBody,
uint256 _gasAmount,
uint256 _gasPayment,
address _gasPaymentRefundAddress
) internal returns (bytes32 _messageId) {
_messageId = _dispatch(_destinationDomain, _messageBody);
// Call the IGP even if the gas payment is zero. This is to support on-chain
// fee quoting in IGPs, which should always revert if gas payment is insufficient.
interchainGasPaymaster.payForGas{value: _gasPayment}(
_messageId,
_destinationDomain,
_gasAmount,
_gasPaymentRefundAddress
);
}
/**
* @notice Dispatches a message to an enrolled router via the provided Mailbox.
* @dev Does not pay interchain gas.
* @dev Reverts if there is no enrolled router for _destinationDomain.
* @param _destinationDomain The domain of the chain to which to send the message.
* @param _messageBody Raw bytes content of message.
*/
function _dispatch(uint32 _destinationDomain, bytes memory _messageBody)
internal
virtual
returns (bytes32)
{
// Ensure that destination chain has an enrolled router.
bytes32 _router = _mustHaveRemoteRouter(_destinationDomain);
return mailbox.dispatch(_destinationDomain, _router, _messageBody);
}
}