/
MsgExampleInOrder.sol
49 lines (41 loc) · 1.97 KB
/
MsgExampleInOrder.sol
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// SPDX-License-Identifier: GPL-3.0-only
pragma solidity >=0.8.9;
import "../../framework/MessageApp.sol";
// a simple example to enforce in-order message delivery
contract MsgExampleInOrder is MessageApp {
event MessageReceived(address srcContract, uint64 srcChainId, address sender, uint64 seq, bytes message);
// map at source chain. (dstChainId, dstContract) -> seq
mapping(uint64 => mapping(address => uint64)) public sendSeq;
// map at destination chain (srcChainId, srcContract) -> seq
mapping(uint64 => mapping(address => uint64)) public recvSeq;
constructor(address _messageBus) MessageApp(_messageBus) {}
// called by user on source chain to send cross-chain message
function sendMessage(
address _dstContract,
uint64 _dstChainId,
bytes calldata _message
) external payable {
uint64 seq = sendSeq[_dstChainId][_dstContract];
bytes memory message = abi.encode(msg.sender, seq, _message);
sendMessage(_dstContract, _dstChainId, message, msg.value);
sendSeq[_dstChainId][_dstContract] += 1;
}
// called by MessageBus on destination chain to receive message
function executeMessage(
address _srcContract,
uint64 _srcChainId,
bytes calldata _message,
address // executor
) external payable override onlyMessageBus returns (ExecutionStatus) {
(address sender, uint64 seq, bytes memory message) = abi.decode((_message), (address, uint64, bytes));
uint64 expectedSeq = recvSeq[_srcChainId][_srcContract];
if (seq != expectedSeq) {
// sequence number not expected, let executor retry.
// Note: cannot revert here, because once a message execute tx is reverted, it cannot be retried later.
return ExecutionStatus.Retry;
}
emit MessageReceived(_srcContract, _srcChainId, sender, seq, message);
recvSeq[_srcChainId][_srcContract] += 1;
return ExecutionStatus.Success;
}
}