// SPDX-License-Identifier: MIT pragma solidity 0.8.19;
import {IRouterClient} from "@chainlink/contracts-ccip/src/v0.8/ccip/interfaces/IRouterClient.sol"; import {OwnerIsCreator} from "@chainlink/contracts-ccip/src/v0.8/shared/access/OwnerIsCreator.sol"; import {Client} from "@chainlink/contracts-ccip/src/v0.8/ccip/libraries/Client.sol"; import {CCIPReceiver} from "@chainlink/contracts-ccip/src/v0.8/ccip/applications/CCIPReceiver.sol"; import {IERC20} from "@chainlink/contracts-ccip/src/v0.8/vendor/openzeppelin-solidity/v4.8.3/contracts/token/ERC20/IERC20.sol"; import {SafeERC20} from "@chainlink/contracts-ccip/src/v0.8/vendor/openzeppelin-solidity/v4.8.3/contracts/token/ERC20/utils/SafeERC20.sol";
/**
- THIS IS AN EXAMPLE CONTRACT THAT USES HARDCODED VALUES FOR CLARITY.
- THIS IS AN EXAMPLE CONTRACT THAT USES UN-AUDITED CODE.
- DO NOT USE THIS CODE IN PRODUCTION. */
/// @title - A simple messenger contract for sending/receving string data across chains. contract Messenger is CCIPReceiver, OwnerIsCreator { using SafeERC20 for IERC20;
// Custom errors to provide more descriptive revert messages.
error NotEnoughBalance(uint256 currentBalance, uint256 calculatedFees); // Used to make sure contract has enough balance.
error NothingToWithdraw(); // Used when trying to withdraw Ether but there's nothing to withdraw.
error FailedToWithdrawEth(address owner, address target, uint256 value); // Used when the withdrawal of Ether fails.
error DestinationChainNotAllowlisted(uint64 destinationChainSelector); // Used when the destination chain has not been allowlisted by the contract owner.
error SourceChainNotAllowlisted(uint64 sourceChainSelector); // Used when the source chain has not been allowlisted by the contract owner.
error SenderNotAllowlisted(address sender); // Used when the sender has not been allowlisted by the contract owner.
error InvalidReceiverAddress(); // Used when the receiver address is 0.
// Event emitted when a message is sent to another chain.
event MessageSent(
bytes32 indexed messageId, // The unique ID of the CCIP message.
uint64 indexed destinationChainSelector, // The chain selector of the destination chain.
address receiver, // The address of the receiver on the destination chain.
string text, // The text being sent.
address feeToken, // the token address used to pay CCIP fees.
uint256 fees // The fees paid for sending the CCIP message.
);
// Event emitted when a message is received from another chain.
event MessageReceived(
bytes32 indexed messageId, // The unique ID of the CCIP message.
uint64 indexed sourceChainSelector, // The chain selector of the source chain.
address sender, // The address of the sender from the source chain.
string text // The text that was received.
);
bytes32 private s_lastReceivedMessageId; // Store the last received messageId.
string private s_lastReceivedText; // Store the last received text.
// Mapping to keep track of allowlisted destination chains.
mapping(uint64 => bool) public allowlistedDestinationChains;
// Mapping to keep track of allowlisted source chains.
mapping(uint64 => bool) public allowlistedSourceChains;
// Mapping to keep track of allowlisted senders.
mapping(address => bool) public allowlistedSenders;
IERC20 private s_linkToken;
/// @notice Constructor initializes the contract with the router address.
/// @param _router The address of the router contract.
/// @param _link The address of the link contract.
constructor(address _router, address _link) CCIPReceiver(_router) {
s_linkToken = IERC20(_link);
}
/// @dev Modifier that checks if the chain with the given destinationChainSelector is allowlisted.
/// @param _destinationChainSelector The selector of the destination chain.
modifier onlyAllowlistedDestinationChain(uint64 _destinationChainSelector) {
if (!allowlistedDestinationChains[_destinationChainSelector])
revert DestinationChainNotAllowlisted(_destinationChainSelector);
_;
}
/// @dev Modifier that checks if the chain with the given sourceChainSelector is allowlisted and if the sender is allowlisted.
/// @param _sourceChainSelector The selector of the destination chain.
/// @param _sender The address of the sender.
modifier onlyAllowlisted(uint64 _sourceChainSelector, address _sender) {
if (!allowlistedSourceChains[_sourceChainSelector])
revert SourceChainNotAllowlisted(_sourceChainSelector);
if (!allowlistedSenders[_sender]) revert SenderNotAllowlisted(_sender);
_;
}
/// @dev Modifier that checks the receiver address is not 0.
/// @param _receiver The receiver address.
modifier validateReceiver(address _receiver) {
if (_receiver == address(0)) revert InvalidReceiverAddress();
_;
}
/// @dev Updates the allowlist status of a destination chain for transactions.
function allowlistDestinationChain(
uint64 _destinationChainSelector,
bool allowed
) external onlyOwner {
allowlistedDestinationChains[_destinationChainSelector] = allowed;
}
/// @dev Updates the allowlist status of a source chain for transactions.
function allowlistSourceChain(
uint64 _sourceChainSelector,
bool allowed
) external onlyOwner {
allowlistedSourceChains[_sourceChainSelector] = allowed;
}
/// @dev Updates the allowlist status of a sender for transactions.
function allowlistSender(address _sender, bool allowed) external onlyOwner {
allowlistedSenders[_sender] = allowed;
}
/// @notice Sends data to receiver on the destination chain.
/// @notice Pay for fees in LINK.
/// @dev Assumes your contract has sufficient LINK.
/// @param _destinationChainSelector The identifier (aka selector) for the destination blockchain.
/// @param _receiver The address of the recipient on the destination blockchain.
/// @param _text The text to be sent.
/// @return messageId The ID of the CCIP message that was sent.
function sendMessagePayLINK(
uint64 _destinationChainSelector,
address _receiver,
string calldata _text
)
external
onlyOwner
onlyAllowlistedDestinationChain(_destinationChainSelector)
validateReceiver(_receiver)
returns (bytes32 messageId)
{
// Create an EVM2AnyMessage struct in memory with necessary information for sending a cross-chain message
Client.EVM2AnyMessage memory evm2AnyMessage = _buildCCIPMessage(
_receiver,
_text,
address(s_linkToken)
);
// Initialize a router client instance to interact with cross-chain router
IRouterClient router = IRouterClient(this.getRouter());
// Get the fee required to send the CCIP message
uint256 fees = router.getFee(_destinationChainSelector, evm2AnyMessage);
if (fees > s_linkToken.balanceOf(address(this)))
revert NotEnoughBalance(s_linkToken.balanceOf(address(this)), fees);
// approve the Router to transfer LINK tokens on contract's behalf. It will spend the fees in LINK
s_linkToken.approve(address(router), fees);
// Send the CCIP message through the router and store the returned CCIP message ID
messageId = router.ccipSend(_destinationChainSelector, evm2AnyMessage);
// Emit an event with message details
emit MessageSent(
messageId,
_destinationChainSelector,
_receiver,
_text,
address(s_linkToken),
fees
);
// Return the CCIP message ID
return messageId;
}
/// @notice Sends data to receiver on the destination chain.
/// @notice Pay for fees in native gas.
/// @dev Assumes your contract has sufficient native gas tokens.
/// @param _destinationChainSelector The identifier (aka selector) for the destination blockchain.
/// @param _receiver The address of the recipient on the destination blockchain.
/// @param _text The text to be sent.
/// @return messageId The ID of the CCIP message that was sent.
function sendMessagePayNative(
uint64 _destinationChainSelector,
address _receiver,
string calldata _text
)
external
onlyOwner
onlyAllowlistedDestinationChain(_destinationChainSelector)
validateReceiver(_receiver)
returns (bytes32 messageId)
{
// Create an EVM2AnyMessage struct in memory with necessary information for sending a cross-chain message
Client.EVM2AnyMessage memory evm2AnyMessage = _buildCCIPMessage(
_receiver,
_text,
address(0)
);
// Initialize a router client instance to interact with cross-chain router
IRouterClient router = IRouterClient(this.getRouter());
// Get the fee required to send the CCIP message
uint256 fees = router.getFee(_destinationChainSelector, evm2AnyMessage);
if (fees > address(this).balance)
revert NotEnoughBalance(address(this).balance, fees);
// Send the CCIP message through the router and store the returned CCIP message ID
messageId = router.ccipSend{value: fees}(
_destinationChainSelector,
evm2AnyMessage
);
// Emit an event with message details
emit MessageSent(
messageId,
_destinationChainSelector,
_receiver,
_text,
address(0),
fees
);
// Return the CCIP message ID
return messageId;
}
/// handle a received message
function _ccipReceive(
Client.Any2EVMMessage memory any2EvmMessage
)
internal
override
onlyAllowlisted(
any2EvmMessage.sourceChainSelector,
abi.decode(any2EvmMessage.sender, (address))
) // Make sure source chain and sender are allowlisted
{
s_lastReceivedMessageId = any2EvmMessage.messageId; // fetch the messageId
s_lastReceivedText = abi.decode(any2EvmMessage.data, (string)); // abi-decoding of the sent text
emit MessageReceived(
any2EvmMessage.messageId,
any2EvmMessage.sourceChainSelector, // fetch the source chain identifier (aka selector)
abi.decode(any2EvmMessage.sender, (address)), // abi-decoding of the sender address,
abi.decode(any2EvmMessage.data, (string))
);
}
/// @notice Construct a CCIP message.
/// @dev This function will create an EVM2AnyMessage struct with all the necessary information for sending a text.
/// @param _receiver The address of the receiver.
/// @param _text The string data to be sent.
/// @param _feeTokenAddress The address of the token used for fees. Set address(0) for native gas.
/// @return Client.EVM2AnyMessage Returns an EVM2AnyMessage struct which contains information for sending a CCIP message.
function _buildCCIPMessage(
address _receiver,
string calldata _text,
address _feeTokenAddress
) private pure returns (Client.EVM2AnyMessage memory) {
// Create an EVM2AnyMessage struct in memory with necessary information for sending a cross-chain message
return
Client.EVM2AnyMessage({
receiver: abi.encode(_receiver), // ABI-encoded receiver address
data: abi.encode(_text), // ABI-encoded string
tokenAmounts: new Client.EVMTokenAmount[](0), // Empty array aas no tokens are transferred
extraArgs: Client._argsToBytes(
// Additional arguments, setting gas limit
Client.EVMExtraArgsV1({gasLimit: 200_000})
),
// Set the feeToken to a feeTokenAddress, indicating specific asset will be used for fees
feeToken: _feeTokenAddress
});
}
/// @notice Fetches the details of the last received message.
/// @return messageId The ID of the last received message.
/// @return text The last received text.
function getLastReceivedMessageDetails()
external
view
returns (bytes32 messageId, string memory text)
{
return (s_lastReceivedMessageId, s_lastReceivedText);
}
/// @notice Fallback function to allow the contract to receive Ether.
/// @dev This function has no function body, making it a default function for receiving Ether.
/// It is automatically called when Ether is sent to the contract without any data.
receive() external payable {}
/// @notice Allows the contract owner to withdraw the entire balance of Ether from the contract.
/// @dev This function reverts if there are no funds to withdraw or if the transfer fails.
/// It should only be callable by the owner of the contract.
/// @param _beneficiary The address to which the Ether should be sent.
function withdraw(address _beneficiary) public onlyOwner {
// Retrieve the balance of this contract
uint256 amount = address(this).balance;
// Revert if there is nothing to withdraw
if (amount == 0) revert NothingToWithdraw();
// Attempt to send the funds, capturing the success status and discarding any return data
(bool sent, ) = _beneficiary.call{value: amount}("");
// Revert if the send failed, with information about the attempted transfer
if (!sent) revert FailedToWithdrawEth(msg.sender, _beneficiary, amount);
}
/// @notice Allows the owner of the contract to withdraw all tokens of a specific ERC20 token.
/// @dev This function reverts with a 'NothingToWithdraw' error if there are no tokens to withdraw.
/// @param _beneficiary The address to which the tokens will be sent.
/// @param _token The contract address of the ERC20 token to be withdrawn.
function withdrawToken(
address _beneficiary,
address _token
) public onlyOwner {
// Retrieve the balance of this contract
uint256 amount = IERC20(_token).balanceOf(address(this));
// Revert if there is nothing to withdraw
if (amount == 0) revert NothingToWithdraw();
IERC20(_token).safeTransfer(_beneficiary, amount);
}
}