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Technical Reference

Functions​

All transactions to the UniversalRouter are processed through the UniversalRouter.execute functions:

  • execute(bytes calldata commands, bytes[] calldata inputs, uint256 deadline)
  • execute(bytes calldata commands, bytes[] calldata inputs)

The first function allows setting a transaction deadline. If the block.timestamp surpasses the provided deadline, the transaction will revert. Otherwise, both functions execute identically.

These functions operate like a simplified virtual machine (VM). They accept a list of commands and corresponding inputs, executing them in the specified order.

Command Structure​

The first parameter (bytes calldata commands) is a list of commands for the contract to execute, ordered as intended. Each command is encoded in a single byte, divided as follows:

01 23 4 5 6 7
frcommand

f​

A single bit flag indicating whether the command can revert independently without causing the entire transaction to fail:

  • If f is 0 (false) and the command reverts, the entire transaction fails, and subsequent commands are not executed.
  • If f is 1 (true) and the command reverts, the transaction proceeds, enabling partial fills. If using this flag, ensure to include further commands to utilize any leftover funds in the UniversalRouter contract.

r​

Two unused bits reserved for future use. These bits can be set to 0 to save gas, with any provided values ignored. Future versions of the UniversalRouter might utilize these bits for additional functionalities.

command​

A 5-bit unique identifier for the command to execute.

Commands not defined at present will cause the transaction to revert with InvalidCommandType.

The table below lists the complete set of commands:

CommandValue
0x02PERMIT2_TRANSFER_FROM
0x03PERMIT2_PERMIT_BATCH
0x04SWEEP
0x05TRANSFER
0x06PAY_PORTION
0x08V2_SWAP_EXACT_IN
0x09V2_SWAP_EXACT_OUT
0x0aPERMIT2_PERMIT
0x0bWRAP_ETH
0x0cUNWRAP_WETH
0x0dPERMIT2_TRANSFER_FROM_BATCH

Command Details​

Each command is followed by specific parameters:

PERMIT2_TRANSFER_FROM​

  • address: Token to fetch from Permit2
  • address: Recipient of the fetched tokens
  • uint256: Amount of tokens to fetch

The tokens are fetched from the msg.sender of the transaction.

PERMIT2_PERMIT_BATCH​

  • IAllowanceTransfer.PermitBatch: PermitBatch struct detailing Permit2 permits to execute
  • bytes: Signature for Permit2

The signer of the permits must be the msg.sender of the transaction.

SWEEP​

  • address: ERC20 token to sweep (or Constants.STEAMX for STEAMX)
  • address: Recipient of the sweep
  • uint256: Minimum tokens to receive from the sweep

TRANSFER​

  • address: ERC20 token to transfer (or Constants.STEAMX for STEAMX)
  • address: Recipient of the transfer
  • uint256: Amount to transfer

PAY_PORTION​

  • address: ERC20 token to transfer (or Constants.STEAMX for STEAMX)
  • address: Recipient of the transfer
  • uint256: Percentage of the contract's balance to transfer (in basis points)

V2_SWAP_EXACT_IN​

  • address: Recipient of the trade output
  • uint256: Amount of input tokens for the trade
  • uint256: Minimum desired output tokens
  • address[]: Rails Network SwapV2 token path for the trade
  • bool: Flag indicating whether input tokens should come from msg.sender (via Permit2) or are already in the UniversalRouter

V2_SWAP_EXACT_OUT​

  • address: Recipient of the trade output
  • uint256: Amount of output tokens to receive
  • uint256: Maximum input tokens to spend
  • address[]: Rails Network SwapV2 token path for the trade
  • bool: Flag indicating whether input tokens should come from msg.sender (via Permit2) or are already in the UniversalRouter

PERMIT2_PERMIT​

  • IAllowanceTransfer.PermitSingle: PermitSingle struct outlining the Permit2 permit to execute
  • bytes: Signature for Permit2

The signer of the permit must be the msg.sender of the transaction.

WRAP_ETH​

  • address: Recipient of the WSTEAMX
  • uint256: Amount of STEAMX to wrap

UNWRAP_WETH​

  • address: Recipient of the STEAMX
  • uint256: Minimum required STEAMX to receive from the unwrapping

PERMIT2_TRANSFER_FROM_BATCH​

  • IAllowanceTransfer.AllowanceTransferDetails[]: Array of AllowanceTransferDetails structs, each describing a Permit2 transfer to perform

SWEEP_ERC721​

  • address: ERC721 token address to transfer
  • address: Recipient of the transfer
  • uint256: Token ID to transfer

NFT20​

  • uint256: STEAMX value to forward to the NFT20 contract
  • bytes: Calldata to call the NFT20 contract

FOUNDATION​

  • uint256: STEAMX value to forward to the Foundation contract
  • bytes: Calldata to call the Foundation contract
  • address: Recipient of the ERC721
  • address: ERC721 token address
  • uint256: ID of the ERC721

SWEEP_ERC1155​

  • address: ERC1155 token address to sweep
  • address: Recipient of the sweep
  • uint256: Token ID to sweep
  • uint256: Minimum tokens to receive from the sweep