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Community ContractsAPI Reference

Crosschain

Smart contract crosschain utilities and implementations

AnthropicOpen in Claude

Gateways are contracts that enable cross-chain communication. These can either be a message source or a destination according to ERC-7786.

  • ERC7786Receiver: ERC-7786 cross-chain message receiver.
  • ERC7786OpenBridge: ERC-7786 "N out of M" gateway. Sends a message through M gateways and executes on the destination if N received it.

Developers can access interoperability protocols through gateway adapters. The library includes the following gateway adapters:

Gateways

ERC7786OpenBridge

Clients

ERC7786Receiver

Adapters

Axelar

AxelarGatewayAdapter

ERC7786OpenBridge

import "@openzeppelin/community-contracts/crosschain/ERC7786OpenBridge.sol";

N of M gateway: Sends your message through M independent gateways. It will be delivered to the receiver by an equivalent bridge on the destination chain if N of the M gateways agree.

Functions

Pausable

Ownable

IERC7786Receiver

IERC7786GatewaySource

Events

Pausable

Ownable

IERC7786Receiver

IERC7786GatewaySource

Errors

Pausable

Ownable

IERC7786Receiver

IERC7786GatewaySource

constructor(address owner_, address[] gateways_, uint8 threshold_)

public

#

supportsAttribute(bytes4) → bool

public

#

Getter to check whether an attribute is supported or not.

sendMessage(bytes recipient, bytes payload, bytes[] attributes) → bytes32 sendId

public

#

Using memory instead of calldata avoids stack too deep errors

receiveMessage(bytes32, bytes sender, bytes payload) → bytes4

public

#

This function serves a dual purpose:

It will be called by ERC-7786 gateways with message coming from the the corresponding bridge on the source chain. These "signals" are tracked until the threshold is reached. At that point the message is sent to the destination.

It can also be called by anyone (including an ERC-7786 gateway) to retry the execution. This can be useful if the automatic execution (that is triggered when the threshold is reached) fails, and someone wants to retry it.

When a message is forwarded by a known gateway, a ERC7786OpenBridge.Received event is emitted. If a known gateway calls this function more than once (for a given message), only the first call is counts toward the threshold and emits an ERC7786OpenBridge.Received event.

This function revert if:

  • the message is not properly formatted or does not originate from the registered bridge on the source chain.
  • someone tries re-execute a message that was already successfully delivered. This includes gateways that call this function a second time with a message that was already executed.
  • the execution of the message (on the IERC7786Receiver receiver) is successful but fails to return the executed value.

This function does not revert if:

  • A known gateway delivers a message for the first time, and that message was already executed. In that case the message is NOT re-executed, and the correct "magic value" is returned.
  • The execution of the message (on the IERC7786Receiver receiver) reverts. In that case a ERC7786OpenBridge.ExecutionFailed event is emitted.

This function emits:

interface requires this function to be payable. Even if we don't expect any value, a gateway may pass some value for unknown reason. In that case we want to register this gateway having delivered the message and not revert. Any value accrued that way can be recovered by the admin using the ERC7786OpenBridge.sweep function.

getGateways() → address[]

public

#

getThreshold() → uint8

public

#

getRemoteBridge(bytes chain) → bytes

public

#

getRemoteBridge(bytes2 chainType, bytes chainReference) → bytes

public

#

addGateway(address gateway)

public

#

removeGateway(address gateway)

public

#

setThreshold(uint8 newThreshold)

public

#

registerRemoteBridge(bytes bridge)

public

#

pause()

public

#

unpause()

public

#

sweep(address payable to)

public

#

Recovery method in case value is ever received through ERC7786OpenBridge.receiveMessage

_addGateway(address gateway)

internal

#

_removeGateway(address gateway)

internal

#

_setThreshold(uint8 newThreshold)

internal

#

_registerRemoteBridge(bytes bridge)

internal

#

OutboxDetails(bytes32 indexed sendId, struct ERC7786OpenBridge.Outbox[] outbox)

event

#

Received(bytes32 indexed receiveId, address gateway)

event

#

ExecutionSuccess(bytes32 indexed receiveId)

event

#

ExecutionFailed(bytes32 indexed receiveId)

event

#

GatewayAdded(address indexed gateway)

event

#

GatewayRemoved(address indexed gateway)

event

#

ThresholdUpdated(uint8 threshold)

event

#

RemoteRegistered(bytes remote)

event

#

UnsupportedNativeTransfer()

error

#

ERC7786OpenBridgeInvalidCrosschainSender()

error

#

ERC7786OpenBridgeAlreadyExecuted()

error

#

ERC7786OpenBridgeRemoteNotRegistered(bytes2 chainType, bytes chainReference)

error

#

ERC7786OpenBridgeGatewayAlreadyRegistered(address gateway)

error

#

ERC7786OpenBridgeGatewayNotRegistered(address gateway)

error

#

ERC7786OpenBridgeThresholdViolation()

error

#

ERC7786OpenBridgeInvalidExecutionReturnValue()

error

#

RemoteAlreadyRegistered(bytes remote)

error

#

AxelarGatewayAdapter

import "@openzeppelin/community-contracts/crosschain/axelar/AxelarGatewayAdapter.sol";

Implementation of an ERC-7786 gateway destination adapter for the Axelar Network in dual mode.

The contract implements AxelarExecutable's ERC7579DelayedExecutor._execute function to execute the message, converting Axelar's native workflow into the standard ERC-7786.

While both ERC-7786 and Axelar do support non-evm chains, this adaptor does not. This limitation comes from the translation of the ERC-7930 interoperable address (binary objects -- bytes) to strings. This is necessary because Axelar uses string to represent addresses. For EVM network, this adapter uses a checksum hex string representation. Other networks would require a different encoding. Ideally we would have a single encoding for all networks (could be base58, base64, ...) but Axelar doesn't support that.

Functions

AxelarExecutable

IAxelarExecutable

Ownable

IERC7786GatewaySource

Events

AxelarExecutable

IAxelarExecutable

Ownable

IERC7786GatewaySource

Errors

AxelarExecutable

IAxelarExecutable

Ownable

IERC7786GatewaySource

constructor(contract IAxelarGateway gateway, address initialOwner)

public

#

Initializes the contract with the Axelar gateway and the initial owner.

getAxelarChain(bytes input) → string output

public

#

Returns the Axelar chain identifier for a given binary interoperable chain id.

getErc7930Chain(string input) → bytes output

public

#

Returns the binary interoperable chain id for a given Axelar chain identifier.

getRemoteGateway(bytes chain) → bytes

public

#

Returns the address of the remote gateway for a given binary interoperable chain id.

getRemoteGateway(bytes2 chainType, bytes chainReference) → bytes

public

#

Returns the address of the remote gateway for a given chainType and chainReference.

registerChainEquivalence(bytes chain, string axelar)

public

#

Registers a chain equivalence between a binary interoperable chain id and an Axelar chain identifier.

registerRemoteGateway(bytes remote)

public

#

Registers the address of a remote gateway.

supportsAttribute(bytes4) → bool

public

#

Getter to check whether an attribute is supported or not.

sendMessage(bytes recipient, bytes payload, bytes[] attributes) → bytes32

external

#

Endpoint for creating a new message. If the message requires further (gateway specific) processing before it can be sent to the destination chain, then a non-zero outboxId must be returned. Otherwise, the message MUST be sent and this function must return 0.

If any of the attributes is not supported, this function SHOULD revert with an IERC7786GatewaySource.UnsupportedAttribute error. Other errors SHOULD revert with errors not specified in ERC-7786.

_execute(bytes32 commandId, string axelarSourceChain, string axelarSourceAddress, bytes adapterPayload)

internal

#

Execution of a cross-chain message.

In this function:

  • axelarSourceChain is in the Axelar format. It should not be expected to be a proper ERC-7930 format
  • axelarSourceAddress is the sender of the Axelar message. That should be the remote gateway on the chain which the message originates from. It is NOT the sender of the ERC-7786 crosschain message.

Proper ERC-7930 encoding of the crosschain message sender can be found in the message

_stringifyAddress(bytes2 chainType, bytes addr) → string

internal

#

ERC-7930 to Axelar address translation. Currently only supports EVM chains.

RegisteredRemoteGateway(bytes remote)

event

#

A remote gateway has been registered for a chain.

RegisteredChainEquivalence(bytes erc7930binary, string axelar)

event

#

A chain equivalence has been registered.

UnsupportedNativeTransfer()

error

#

InvalidOriginGateway(string axelarSourceChain, string axelarSourceAddress)

error

#

ReceiverExecutionFailed()

error

#

UnsupportedChainType(bytes2 chainType)

error

#

UnsupportedERC7930Chain(bytes erc7930binary)

error

#

UnsupportedAxelarChain(string axelar)

error

#

InvalidChainIdentifier(bytes erc7930binary)

error

#

ChainEquivalenceAlreadyRegistered(bytes erc7930binary, string axelar)

error

#

RemoteGatewayAlreadyRegistered(bytes2 chainType, bytes chainReference)

error

#

ERC7786Attributes

import "@openzeppelin/community-contracts/crosschain/utils/ERC7786Attributes.sol";

Library of helper to parse/process ERC-7786 attributes

Functions

tryDecodeRequestRelay(bytes attribute) → bool success, uint256 value, uint256 gasLimit, address refundRecipient

internal

#

Parse the requestRelay(uint256,uint256,address) (0x4cbb573a) attribute into its components.

ERC7786Receiver

import "@openzeppelin/community-contracts/crosschain/utils/ERC7786Receiver.sol";

Base implementation of an ERC-7786 compliant cross-chain message receiver.

This abstract contract exposes the receiveMessage function that is used for communication with (one or multiple) destination gateways. This contract leaves two functions unimplemented:

ERC7786Receiver._isKnownGateway, an internal getter used to verify whether an address is recognised by the contract as a valid ERC-7786 destination gateway. One or multiple gateway can be supported. Note that any malicious address for which this function returns true would be able to impersonate any account on any other chain sending any message.

ERC7786Receiver._processMessage, the internal function that will be called with any message that has been validated.

Functions

IERC7786Receiver

Errors

IERC7786Receiver

receiveMessage(bytes32 receiveId, bytes sender, bytes payload) → bytes4

public

#

Endpoint for receiving cross-chain message.

This function may be called directly by the gateway.

_isKnownGateway(address instance) → bool

internal

#

Virtual getter that returns whether an address is a valid ERC-7786 gateway.

_processMessage(address gateway, bytes32 receiveId, bytes sender, bytes payload)

internal

#

Virtual function that should contain the logic to execute when a cross-chain message is received.

ERC7786ReceiverInvalidGateway(address gateway)

error

#

ERC7786ReceivePassiveModeValue()

error

#

WormholeGatewayAdapter

import "@openzeppelin/community-contracts/crosschain/wormhole/WormholeGatewayAdapter.sol";

An ERC-7786 compliant adapter to send and receive messages via Wormhole.

Note: only EVM chains are currently supported

Modifiers

Functions

Ownable

IWormholeReceiver

IERC7786GatewaySource

Events

Ownable

IWormholeReceiver

IERC7786GatewaySource

Errors

Ownable

IWormholeReceiver

IERC7786GatewaySource

onlyWormholeRelayer()

internal

#

constructor(contract IWormholeRelayer wormholeRelayer, uint16 wormholeChainId, address initialOwner)

public

#

Initializes the contract with the Wormhole gateway and the initial owner.

relayer() → address

public

#

Returns the local Wormhole relayer

supportedChain(bytes chain) → bool

public

#

Returns whether a binary interoperable chain id is supported.

supportedChain(uint256 chainId) → bool

public

#

Returns whether an EVM chain id is supported.

getWormholeChain(bytes chain) → uint16

public

#

Returns the Wormhole chain id that correspond to a given binary interoperable chain id.

getWormholeChain(uint256 chainId) → uint16

public

#

Returns the Wormhole chain id that correspond to a given EVM chain id.

getChainId(uint16 wormholeId) → uint256

public

#

Returns the EVM chain id for a given Wormhole chain id.

getRemoteGateway(bytes chain) → address

public

#

Returns the address of the remote gateway for a given binary interoperable chain id.

getRemoteGateway(uint256 chainId) → address

public

#

Returns the address of the remote gateway for a given EVM chain id.

registerChainEquivalence(bytes chain, uint16 wormholeId)

public

#

Registers a chain equivalence between a binary interoperable chain id and a Wormhole chain id.

registerChainEquivalence(uint256 chainId, uint16 wormholeId)

public

#

Registers a chain equivalence between an EVM chain id and a Wormhole chain id.

registerRemoteGateway(bytes remote)

public

#

Registers the address of a remote gateway (binary interoperable address version).

registerRemoteGateway(uint256 chainId, address addr)

public

#

Registers the address of a remote gateway (EVM version).

supportsAttribute(bytes4 selector) → bool

public

#

Getter to check whether an attribute is supported or not.

sendMessage(bytes recipient, bytes payload, bytes[] attributes) → bytes32 sendId

external

#

Endpoint for creating a new message. If the message requires further (gateway specific) processing before it can be sent to the destination chain, then a non-zero outboxId must be returned. Otherwise, the message MUST be sent and this function must return 0.

If any of the attributes is not supported, this function SHOULD revert with an IERC7786GatewaySource.UnsupportedAttribute error. Other errors SHOULD revert with errors not specified in ERC-7786.

quoteRelay(bytes recipient, bytes, bytes[], uint256 value, uint256 gasLimit, address) → uint256

external

#

Returns a quote for the value that must be passed to WormholeGatewayAdapter.requestRelay

requestRelay(bytes32 sendId, uint256 gasLimit, address refundRecipient)

external

#

Relay a message that was initiated by ERC7786OpenBridge.sendMessage.

receiveWormholeMessages(bytes adapterPayload, bytes[] additionalMessages, bytes32 wormholeSourceAddress, uint16 wormholeSourceChain, bytes32 deliveryHash)

public

#

MessageRelayed(bytes32 sendId)

event

#

A message was relayed to Wormhole (part of the post processing of the outbox ids created by ERC7786OpenBridge.sendMessage)

RegisteredRemoteGateway(uint256 chainId, address remote)

event

#

A remote gateway has been registered for a chain.

RegisteredChainEquivalence(uint256 chainId, uint16 wormholeId)

event

#

A chain equivalence has been registered.

InvalidAttributeEncoding(bytes attribute)

error

#

DuplicatedAttribute()

error

#

UnauthorizedCaller(address)

error

#

InvalidOriginGateway(uint16 wormholeSourceChain, bytes32 wormholeSourceAddress)

error

#

ReceiverExecutionFailed()

error

#

UnsupportedChainId(uint256 chainId)

error

#

UnsupportedWormholeChain(uint16 wormholeId)

error

#

ChainEquivalenceAlreadyRegistered(uint256 chainId, uint16 wormhole)

error

#

RemoteGatewayAlreadyRegistered(uint256 chainId)

error

#

InvalidSendId(bytes32 sendId)

error

#

AdditionalMessagesNotSupported()

error

#

MessageAlreadyExecuted(uint256 chainId, bytes32 outboxId)

error

#

Account

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GatewaysClientsAdaptersAxelarERC7786OpenBridgeAxelarGatewayAdapterERC7786AttributesERC7786ReceiverWormholeGatewayAdapter