calls.md

description
This section contains a full API reference of all public functions & events related to making and tracking xchain calls.

Calls

Events

XCalled

event XCalled(bytes32 transferId, uint256 nonce, bytes32 messageHash, struct TransferInfo params, address asset, uint256 amount, address local)

Emitted when xcall is called on the origin domain of a transfer.

Parameters

Name	Type	Description
transferId	bytes32	- The unique identifier of the crosschain transfer.
nonce	uint256	- The bridge nonce of the transfer on the origin domain.
messageHash	bytes32	- The hash of the message bytes (containing all transfer info) that were bridged.
params	struct TransferInfo	- The TransferInfo provided to the function.
asset	address	- The asset sent in with xcall
amount	uint256	- The amount sent in with xcall
local	address	- The local asset that is controlled by the bridge and can be burned/minted

ExternalCalldataExecuted

event ExternalCalldataExecuted(bytes32 transferId, bool success, bytes returnData)

Emitted when a transfer has its external data executed

Parameters

Name	Type	Description
transferId	bytes32	- The unique identifier of the crosschain transfer.
success	bool	- Whether calldata succeeded
returnData	bytes	- Return bytes from the IXReceiver

Executed

event Executed(bytes32 transferId, address to, address asset, struct ExecuteArgs args, address local, uint256 amount, address caller)

Emitted when execute is called on the destination domain of a transfer.

execute may be called when providing fast liquidity or when processing a reconciled (slow) transfer.

Parameters

Name	Type	Description
transferId	bytes32	- The unique identifier of the crosschain transfer.
to	address	- The recipient TransferInfo.to provided, created as indexed parameter.
asset	address	- The asset the recipient is given or the external call is executed with. Should be the adopted asset on that chain.
args	struct ExecuteArgs	- The ExecuteArgs provided to the function.
local	address	- The local asset that was either supplied by the router for a fast-liquidity transfer or minted by the bridge in a reconciled (slow) transfer. Could be the same as the adopted asset param.
amount	uint256	- The amount of transferring asset the recipient address receives or the external call is executed with.
caller	address	- The account that called the function.

TransferRelayerFeesIncreased

event TransferRelayerFeesIncreased(bytes32 transferId, uint256 increase, address caller)

Emitted when _bumpTransfer is called by an user on the origin domain both in xcall and bumpTransfer

Parameters

Name	Type	Description
transferId	bytes32	- The unique identifier of the crosschain transaction
increase	uint256	- The additional amount fees increased by
caller	address	- The account that called the function

SlippageUpdated

event SlippageUpdated(bytes32 transferId, uint256 slippage)

Emitted when forceUpdateSlippage is called by an user on the destination domain

Parameters

Name	Type	Description
transferId	bytes32	- The unique identifier of the crosschain transaction
slippage	uint256	- The updated slippage boundary

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Getters

routedTransfers

function routedTransfers(bytes32 _transferId) public view returns (address[])

Gets a list of routers that routed a transfer by transferId.

Parameters

Name	Type	Description
_transferId	bytes32	Unique transfer ID of a given transaction

Return Values

Name	Type	Description
[0]	address[]	Array containing addresses of routers

transferStatus

function transferStatus(bytes32 _transferId) public view returns (enum DestinationTransferStatus)

Gets a transfer's status by transferId. Note - this function MUST be called on the destination chain.

Parameters

Name	Type	Description
_transferId	bytes32	Unique transfer ID of a given transaction

Return Values

Name	Type	Description
[0]	enum	Status of the transfer

domain

function domain() public view returns (uint32)

Gets the domain identifier of the chain.

Parameters

Return Values

Name	Type	Description
[0]	uint32	Domain identifier of the chain

Functions

xcall

function xcall(uint32 _destination, address _to, address _asset, address _delegate, uint256 _amount, uint256 _slippage, bytes _callData, uint256 _relayerFee) external payable returns (bytes32)

Initiates a cross-chain transfer of funds, calldata, and/or various named properties.

For ERC20 transfers, this contract must have approval to transfer the input (transacting) assets. The adopted assets will be swapped for their local (connext-flavored) asset counterparts (i.e. bridgeable tokens) via the configured AMM if necessary. In the event that the adopted assets are local assets, no swap is needed. The local tokens will then be sent via the bridge router. If the local assets are representational for an asset on another chain, we will burn the tokens here. If the local assets are canonical (meaning that the adopted to local asset pairing is native to this chain), we will custody the tokens here.

Parameters

Name	Type	Description
_destination	uint32	The destination chain's Domain ID (not equivalent to “Chain ID”). See [Domains] for details TODO
_to	address	The target address on the destination chain. xcall will send funds to whatever address is specified here regardless of whether it is a contract or EOA. If calldata is provided, xcall will additionally attempt to call xReceive on this contract.
_asset	address	The contract address of the asset to be bridged. If the xcall is calldata-only (e.g. doesn't bridge any funds), any registered asset can be used here as long as amount: 0.
_delegate	address	An address on destination domain that has rights to update slippage tolerance, retry transactions, or revert back to origin in the event that a transaction fails at the destination.
_amount	uint256	The amount of tokens to bridge specified in wei units (i.e. to send 1 USDC, a token with 10^6 decimals, you must specify the amount as 1000000).
_slippage	uint256	The maximum slippage a user is willing to take, in BPS, due to the StableSwap Pool(s), if applicable. For example, to achieve 0.03% slippage tolerance this will be 3.
_callData	bytes	In the case of bridging funds only, this should be empty bytes ("0x"). If calldata is sent, then the encoded calldata must be passed here.
_relayerFee	uint256	(Optional) This is available in an overloaded xcall. If provided, the relayer fee will be taken in _asset rather than the native asset.

Return Values

Name	Type	Description
[0]	bytes32	bytes32 - The transfer ID of the newly created crosschain transfer.

xcallIntoLocal

function xcallIntoLocal(uint32 _destination, address _to, address _asset, address _delegate, uint256 _amount, uint256 _slippage, bytes _callData, uint256 _relayerFee) external payable returns (bytes32)

Helper function that xcalls as normal but forces the receipt of the local (Connext-flavored) asset at destination. This function is used typically to generate nextAssets that can be used to LP into the destination chain stableswap. Params and returned data function exactly the same way as xcall.

execute

function execute(struct ExecuteArgs _args) external returns (bytes32)

Called on a destination domain to disburse correct assets to end recipient and execute any included calldata.

Can be called before or after handle [reconcile] is called (regarding the same transfer), depending on whether the fast liquidity route (i.e. funds provided by routers) is being used for this transfer. As a result, executed calldata (including properties like originSender) may or may not be verified depending on whether the reconcile has been completed (i.e. the optimistic confirmation period has elapsed).

Parameters

Name	Type	Description
_args	struct ExecuteArgs	- ExecuteArgs arguments.

Return Values

Name	Type	Description
[0]	bytes32	bytes32 - The transfer ID of the crosschain transfer. Should match the xcall's transfer ID in order for reconciliation to occur.

bumpTransfer (native asset)

function bumpTransfer(bytes32 _transferId) external payable

Anyone can call this function on the origin domain to increase the relayer fee for a transfer. MUST be called on the origin domain.

Parameters

Name	Type	Description
_transferId	bytes32	- The unique identifier of the crosschain transaction

bumpTransfer (transacting asset)

function bumpTransfer(bytes32 _transferId, address _relayerFeeAsset, uint256 _relayerFee) external payable

Anyone can call this function to increase the relayer fee for a transfer (using the _relayerFeeAsset specified). MUST be called on the origin domain.

Parameters

Name	Type	Description
_transferId	bytes32	- The unique identifier of the crosschain transaction
_relayerfeeAsset	address	- The asset you are bumping fee with
_relayerFee	uint256	- The amount you want to bump transfer fee with

forceUpdateSlippage

function forceUpdateSlippage(struct TransferInfo _params, uint256 _slippage) external

Allows a user-specified account (delegate in xcall) to update the slippage they are willing to take on destination transfers. MUST be called on the destination chain.

Parameters

Name	Type	Description
_params	struct TransferInfo	TransferInfo associated with the transfer
_slippage	uint256	The updated slippage

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Interfaces

xReceive

function xReceive(bytes32 _transferId, uint256 _amount, address _asset, address _originSender, uint32 _origin, bytes _callData) external returns (bytes)

Interface that the Connext contracts call into on the _to address specified during xcall. Developers MUST implement this on the destination chain to receive incoming calldata.

Parameters

Name	Type	Description
_transferId	bytes32	Unique id of the xchain transaction
_amount	uint256	Amount of token, if any, passed into the contract in Wei units
_asset	address	Address of token, if any, passed into the contract
_originSender	address	Address of the contract or EOA that called xcall on the origin chain. NOTE: this param will only be populated if the transaction went through the slow path rather than being executed immediately by a Connext router (see TODO for details)
_origin	uint32	Domain ID of the chain that the transaction is coming from
_calldata	bytes	Data, in bytes, that is passed into xcall on the origin chain