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Verify if Sender is Interchain Messaging

Safety verification of the message sender

We can also leverage the registry to check if msg.sender is a registered Interchain Messaging contract. Previously, we hardcoded this check in the contract:

import "@teleporter/ITeleporterMessenger.sol";
import "@teleporter/ITeleporterReceiver.sol";
 
contract ReceiverOnSubnet is ITeleporterReceiver {
    ITeleporterMessenger public immutable messenger = ITeleporterMessenger(0x253b2784c75e510dD0fF1da844684a1aC0aa5fcf);
 
    string public lastMessage;
 
    function receiveTeleporterMessage(bytes32, address, bytes calldata message) external {
        // Only the Interchain Messaging receiver can deliver a message.
        require(msg.sender == address(messenger), "ReceiverOnSubnet: unauthorized TeleporterMessenger");
 
        // Store the message.
        lastMessage = abi.decode(message, (string));
    }
}

If there was now a new Interchain Messaging contract version that would be used for sending messages, we would have to update the contract.

Instead, we can use the registry to check if the sender is a registered Interchain Messaging contract.

pragma solidity ^0.8.18;
 
import "@teleporter/upgrades/TeleporterRegistry.sol";
import "@teleporter/ITeleporterMessenger.sol";
import "@teleporter/ITeleporterReceiver.sol";
 
contract ReceiverOnDispatchWithRegistry is ITeleporterReceiver {
    // The Interchain Messaging registry contract manages different Interchain Messaging contract versions.
    TeleporterRegistry public immutable teleporterRegistry =
        TeleporterRegistry(0x827364Da64e8f8466c23520d81731e94c8DDe510);
 
    string public lastMessage;
 
    function receiveTeleporterMessage(bytes32, address, bytes calldata message) external {
        // Only a Interchain Messaging Messenger registered in the registry can deliver a message.
        // Function throws an error if msg.sender is not registered.
        teleporterRegistry.getVersionFromAddress(msg.sender);
 
        // Store the message.
        lastMessage = abi.decode(message, (string));
    }
}
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