GPv2VaultRelayer API

Vault relayer contract API for Balancer Vault interactions and token transfers

GPv2VaultRelayer API

The GPv2VaultRelayer contract serves as an intermediary between CoW Protocol’s settlement system and Balancer Vault, facilitating fund transfers and swap execution with protocol fees.

State Variables

address public immutable creator;
IVault public immutable vault;

Access Control

modifier onlyCreator {
    require(msg.sender == creator, "GPv2: not creator");
    _;
}

All external functions are restricted to the creator (settlement contract) through the onlyCreator modifier.

Functions

transferFromAccounts

Moves sell token amounts from user accounts to the settlement contract.

function transferFromAccounts(
    GPv2Transfer.Data[] calldata transfers
) external onlyCreator;

Supports three balance types:

Balance Type	Description
ERC20	Standard ERC20 token transfers
External	Balancer Vault external balances
Internal	Balancer Vault internal balances

batchSwapWithFee

Executes multi-step swaps through Balancer pools and simultaneously collects protocol fees.

function batchSwapWithFee(
    IVault.BatchSwapStep[] calldata swaps,
    IERC20[] calldata tokens,
    IVault.FundManagement calldata funds,
    int256[] calldata limits,
    uint256 deadline,
    GPv2Transfer.Data calldata feeTransfer
) external onlyCreator returns (int256[] memory tokenDeltas);

Parameters:

Name	Type	Description
swaps	BatchSwapStep[]	Batch swap steps to execute
tokens	IERC20[]	Token addresses involved
funds	FundManagement	Fund management configuration
limits	int256[]	Maximum token amounts
deadline	uint256	Transaction deadline
feeTransfer	Transfer.Data	Fee collection transfer

Returns: int256[] - Token deltas indicating amounts sent and received.

The function handles both sell orders (GIVEN_IN) and buy orders (GIVEN_OUT) swap kinds.

Security

• Access restricted exclusively to the creator through onlyCreator
• Unauthorized calls revert with "GPv2: not creator"
• Immutable state prevents tampering
• Users never interact with this contract directly