ViaIntegrationV1

The abstract base contract your project inherits from. It connects to the VIA Gateway, manages endpoint configuration, and routes cross-chain messages.

For the full source code, see Contract Source.

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Messaging

These are the two functions you use in your contract.

messageSend

Send a cross-chain message. Call this from your contract's public functions.

function messageSend(
    uint64 destChainId,
    bytes memory chainData,
    uint16 confirmations
) internal returns (uint256 txId);

Parameter	Type	Description
destChainId	uint64	Chain ID of the destination network
chainData	bytes	ABI-encoded payload
confirmations	uint16	Block confirmations before processing. 0 = fastest, higher = safer.

Returns uint256 txId — unique identifier for tracking the message.

The caller must include msg.value to cover destination chain gas. Reverts with AddressZero if the gateway isn't set, or DestinationChainNotSet if the destination chain has no endpoint.

messageProcess

Override this to handle incoming messages. Called automatically by the gateway after validation.

function messageProcess(
    uint256 txId,
    uint64 sourceChainId,
    bytes32 sender,
    bytes32 recipient,
    bytes memory onChainData,
    bytes memory offChainData,
    uint256 gasRefundAmount
) internal virtual;

Parameter	Type	Description
txId	uint256	Transaction ID from the source chain
sourceChainId	uint64	Chain ID where the message originated
sender	bytes32	Source contract address (left-padded)
recipient	bytes32	This contract's address (left-padded)
onChainData	bytes	The payload from messageSend()
offChainData	bytes	Additional relayer-provided data
gasRefundAmount	uint256	Gas refunded to the relayer

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Configuration

All configuration functions are restricted to onlyProjectOwner.

setMessageGateway

function setMessageGateway(address gateway_) external onlyProjectOwner;

Connect to the VIA Gateway on this chain. Must be called before sending or receiving. Automatically queries the gateway for fee/gas collector addresses and approves their tokens.

setMessageEndpoints

function setMessageEndpoints(
    uint64[] calldata chains,
    bytes32[] calldata endpoints
) external onlyProjectOwner;

Map remote chain IDs to your contract addresses on those chains. Messages from unmapped chains are rejected.

Parameter	Type	Description
chains	uint64[]	Remote chain IDs (e.g., [1, 137, 42161])
endpoints	bytes32[]	Your contract addresses on those chains (left-padded)

setMaxFee

function setMaxFee(uint256 amount) external onlyProjectOwner;

Cap the ERC-20 protocol fee per message. 0 = no cap. Currently fees are zero on all chains.

setMaxGas

function setMaxGas(uint256 amount) external onlyProjectOwner;

Cap the gas refund a relayer can claim per message. 0 = no cap. Only relevant for Ethereum mainnet destinations — see Fees & Gas.

transferProjectOwnership

function transferProjectOwnership(address newOwner) external onlyProjectOwner;

Single-step, immediate transfer. The new owner gets all onlyProjectOwner permissions. Cannot be set to zero address.

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Advanced

Optional functions for enterprise projects that want additional control over security and relay infrastructure.

setSignerWhitelist

function setSignerWhitelist(address addr, bool enabled) external onlyProjectOwner;

Add/remove addresses from the project signer whitelist. Whitelisted addresses can register as Project-layer signers.

setRequiredProjectSignerCounts

function setRequiredProjectSignerCounts(uint256 amount) external onlyProjectOwner;

Set required project-layer signatures. 0 = disabled (rely on VIA and Chain layers only).

setRelayerWhitelist

function setRelayerWhitelist(address addr, bool enabled) external onlyProjectOwner;

Add/remove project-specific relayers.

setIsProjectRelayerRestricted

function setIsProjectRelayerRestricted(bool restricted) external onlyProjectOwner;

When true, only project-whitelisted relayers can deliver messages for your project.

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Helpers

Function	Parameters	Returns	Description
_addressToBytes32	address addr	bytes32	Convert address to bytes32 (left-padded)
_bytes32ToAddress	bytes32 addr	address	Convert bytes32 back to address

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Errors

Error	When
AddressZero	Gateway not set, or transferProjectOwnership to zero address
DestinationChainNotSet	No endpoint configured for the destination chain
InvalidLength	chains and endpoints arrays have different lengths
NotOwner	Caller is not projectOwner
NotGateway	Incoming message not from the configured gateway
InvalidSender	Incoming message from an unrecognized source endpoint
NotAuthorized	Caller not in relayer/signer whitelist