Multi-bridge Message Sender

src/MultiBridgeMessageSender.sol

Features

• Supports sending messages via multiple bridge sender adapters

• Only a predefined dApp contract can use this multi-bridge sender for cross-chain remote calls

• Allows adding and removing bridge sender adapters

• The caller is responsible for determining the fees to be paid to each of the bridges to be used.

• The caller can choose to omit a set of bridges for a given message

• Emits events for sent messages, sender adapter updates, and error when sending messages

Functions

remoteCall

    function remoteCall(
        uint256 _dstChainId,
        address _target,
        bytes calldata _callData,
        uint256 _nativeValue,
        uint256 _expiration,
        address _refundAddress,
        uint256[] calldata _fees,
        uint256 _successThreshold,
        address[] calldata _excludedAdapters
    ) external payable onlyCaller validateExpiration(_expiration)

This function allows a remote function to be called on a destination chain. It does this by sending multiple copies of a cross-chain message through available bridges. Only the predefined caller contract can call this function. The call is successful if a minimum number of bridge adapters, defined by the _successThreshold parameter, successfully dispatch the cross-chain message.

It takes the following parameters:

• _dstChainId: The destination chainId

• _target is the target execution point on the destination chain

• _callData is the data to be sent to _target by low-level call(eg. address(_target).call(_callData))

• _nativeValue is the value to be sent to _target by low-level call (eg. address(_target).call{value: _nativeValue}(_callData))

• _expiration refers to the number of seconds that a message remains valid before it is considered stale and can no longer be executed.

• _refundAddress refers to the refund address for any extra native tokens paid

• _fees refers to the fees to pay to each sender adapter that is not in the exclusion list specified by _excludedAdapters. The fees are in the same order as the sender adapters in the senderAdapters list, after the exclusion list is applied.

• _successThreshold specifies the minimum number of bridges that must successfully dispatch the message for this call to succeed.

• excludedAdapters are the sender adapters to be excluded from relaying the message, in ascending order by address

addSenderAdapters

function addSenderAdapters(address[] calldata _senderAdapters) external onlyOwner

Adds an array of bridge sender adapter addresses, that must be provided in ascending order. This function is only callable by the owner.

removeSenderAdapters

function removeSenderAdapters(address[] calldata _senderAdapters) external onlyOwner

Removes an array of bridge sender adapter addresses, that must be provided in ascending order. This function is only callable by the predefined owner contract.

Events

• MultiBridgeMessageSent: is emitted after a call to remoteCall() completes, sending a given message through one or more bridges. The details of this event should be inspected to see if any bridges have failed.

• MessageSendFailed : is emitted if sending a message through a specific AMB fails.

• SenderAdapterUpdated: is emitted when a sender adapter is added or removed

Dependencies

The contract depends on the following files:

• IMessageSenderAdapter.sol: Interface for bridge sender adapters

• IMultiBridgeMessageReceiver.sol: Interface for MultiBridgeMessageReceiver contracts on the destination chain

• MessageSenderGAC: Global Access Control contract.

• It also uses a Message.sol file for the message structure.