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Technical Reference

Functions​

Transactions to the UniversalRouter all go through the UniversalRouter.execute functions:

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

The first of these functions adds the functionality to allow transactions to have a transaction deadline. If the block.timestamp is after the deadline provided the transaction will revert. After that check, the 2 functions otherwise execute identically.

The execute functions work like a simplified VM - they take in a list of commands, and a list of inputs for the commands and execute them in the order specified.

Command Structure​

The first parameter for the function (bytes calldata commands) is a list of commands for the contract to execute, in the order they should be executed. Each command is encoded in 1 byte, containing the following split of 8 bits:

01 23 4 5 6 7
frcommand

f​

A single bit flag, that signals whether or not the command should be allowed to revert without the whole transaction failing.

  • If f is 0 aka false and the command reverts, then the entire transaction will revert and none of the commands will be executed.
  • If f is 1 aka true and the command reverts, then the transaction will continue, allowing us to achieve partial fills. If using this flag, be careful to include further commands that will remove any funds that could be left unused in the UniversalRouter contract.

r​

2 unused bytes, reserved for future use. Leaving these 2 bits as 0 will save gas, but any value passed into the contract will be ignored. Later versions of the UniversalRouter will likely expand the 5 bits used for command to use at least 1 of these bits.

command​

A 5 bit unique identifier for the command that should be carried out. The values of these commands can be found within Commands.sol, or can be viewed in the table below.

The command types that are not defined do not have an assigned command at this moment in time. Providing one of these identifiers will cause the transaction to revert with InvalidCommandType.

A complete list of commands can be found in the table below:

CommandValue
0x00V3_SWAP_EXACT_IN
0x01V3_SWAP_EXACT_OUT
0x02PERMIT2_TRANSFER_FROM
0x03PERMIT2_PERMIT_BATCH
0x04SWEEP
0x05TRANSFER
0x06PAY_PORTION
0x07
0x08V2_SWAP_EXACT_IN
0x09V2_SWAP_EXACT_OUT
0x0aPERMIT2_PERMIT
0x0bWRAP_ETH
0x0cUNWRAP_WETH
0x0dPERMIT2_TRANSFER_FROM_BATCH
0x0e
0x0f
0x10SEAPORT
0x11LOOKS_RARE_721
0x12NFTX
0x13CRYPTOPUNKS
0x14LOOKS_RARE_1155
0x15OWNER_CHECK_721
0x16OWNER_CHECK_1155
0x17SWEEP_ERC721
0x18X2Y2_721
0x19SUDOSWAP
0x1aNFT20
0x1bX2Y2_1155
0x1cFOUNDATION
0x1dSWEEP_ERC1155
0x1e
0x1f

Command Inputs​

The second parameter for the function is an array of bytes strings. Each element in the array is the abi-encoded input that will be used for the respective command.

commands[i] is the command that will use inputs[i] as its encoded input parameters.

The router uses the command type to know how to decode the encoded input parameters - depending on the command chosen, the required inputs is different.

The input parameters required for each command are outlined below:

V3_SWAP_EXACT_IN​

  • address The recipient of the output of the trade
  • uint256 The amount of input tokens for the trade
  • uint256 The minimum amount of output tokens the user wants
  • bytes The UniswapV3 encoded path to trade along
  • bool A flag for whether the input tokens should come from the msg.sender (through Permit2) or whether the funds are already in the UniversalRouter

V3_SWAP_EXACT_OUT​

  • address The recipient of the output of the trade
  • uint256 The amount of output tokens to receive
  • uint256 The maximum number of input tokens that should be spent
  • bytes The UniswapV3 encoded path to trade along
  • bool A flag for whether the input tokens should come from the msg.sender (through Permit2) or whether the funds are already in the UniversalRouter

PERMIT2_TRANSFER_FROM​

  • address The token to fetch from Permit2
  • address The recipient of the tokens fetched
  • uint256 The amount of token to fetch

The individual that the tokens are fetched from is always the msg.sender of the transaction

PERMIT2_PERMIT_BATCH​

  • IAllowanceTransfer.PermitBatch A PermitBatch struct outlining all of the Permit2 permits to execute.
  • bytes The signature to provide to Permit2

The individual that signed the permits must be the msg.sender of the transaction

SWEEP​

  • address The ERC20 token to sweep (or Constants.ETH for ETH)
  • address The recipient of the sweep
  • uint256 The minimum required tokens to receive from the sweep

TRANSFER​

  • address The ERC20 token to transfer (or Constants.ETH for ETH)
  • address The recipient of the transfer
  • uint256 The amount to transfer

PAY_PORTION​

  • address The ERC20 token to transfer (or Constants.ETH for ETH)
  • address The recipient of the transfer
  • uint256 In basis points, the percentage of the contract’s balance to transfer

V2_SWAP_EXACT_IN​

  • address The recipient of the output of the trade
  • uint256 The amount of input tokens for the trade
  • uint256 The minimum amount of output tokens the user wants
  • address[] The UniswapV2 token path to trade along
  • bool A flag for whether the input tokens should come from the msg.sender (through Permit2) or whether the funds are already in the UniversalRouter

V2_SWAP_EXACT_OUT​

  • address The recipient of the output of the trade
  • uint256 The amount of output tokens to receive
  • uint256 The maximum number of input tokens that should be spent
  • address[] The UniswapV2 token path to trade along
  • bool A flag for whether the input tokens should come from the msg.sender (through Permit2) or whether the funds are already in the UniversalRouter

PERMIT2_PERMIT​

  • IAllowanceTransfer.PermitSingle A PermitSingle struct outlining the Permit2 permit to execute
  • bytes The signature to provide to Permit2

The individual that signed the permit must be the msg.sender of the transaction

WRAP_ETH​

  • address The recipient of the WETH
  • uint256 The amount of ETH to wrap

UNWRAP_ETH​

  • address The recipient of the ETH
  • uint256 The minimum required ETH to receive from the unwrapping

PERMIT2_TRANSFER_FROM_BATCH​

  • IAllowanceTransfer.AllowanceTransferDetails[] An array of AllowanceTransferDetails structs that each describe a Permit2 transfer to perform

SEAPORT​

  • uint256 The ETH value to forward to the Seaport contract
  • bytes The calldata to use to call the Seaport contract

LOOKS_RARE_721​

  • uint256 The ETH value to forward to the LooksRare contract
  • bytes The calldata to use to call the LooksRare contract
  • address The recipient of the ERC721
  • address The ERC721 token address
  • uint256 The ID of the ERC721

NFTX​

  • uint256 The ETH value to forward to the NFTX contract
  • bytes The calldata to use to call the NFTX contract

CRYPTOPUNKS​

  • uint256 The PunkID to purchase
  • address The recipient for the cryptopunk
  • uint256 The ETH value to forward to the Cryptopunks contract

LOOKS_RARE_1155​

  • uint256 The ETH value to forward to the LooksRare contract
  • bytes The calldata to use to call the LooksRare contract
  • address The recipient of the ERC1155
  • address The ERC1155 token address
  • uint256 The ID of the ERC1155
  • uint256 The amount of the ERC1155 to transfer

OWNER_CHECK_721​

  • address The required owner of the ERC721
  • address The ERC721 token address
  • uint256 The ID of the ERC721

OWNER_CHECK_1155​

  • address The required owner of the ERC1155
  • address The ERC721 token address
  • uint256 The ID of the ERC1155
  • uint256 The minimum required amount of the ERC1155

SWEEP_ERC721​

  • address The ERC721 token address to transfer
  • address The recipient of the transfer
  • uint256 The token ID to transfer

X2Y2_721​

  • uint256 The ETH value to forward to the X2Y2 contract
  • bytes The calldata to use to call the X2Y2 contract
  • address The recipient of the ERC721
  • address The ERC721 token address
  • uint256 The ID of the ERC721

SUDOSWAP​

  • uint256 The ETH value to forward to the Sudoswap contract
  • bytes The calldata to use to call the Sudoswap contract

NFT20​

  • uint256 The ETH value to forward to the NFT20 contract
  • bytes The calldata to use to call the NFT20 contract

X2Y2_1155​

  • uint256 The ETH value to forward to the X2Y2 contract
  • bytes The calldata to use to call the X2Y2 contract
  • address The recipient of the ERC1155
  • address The ERC1155 token address
  • uint256 The ID of the ERC1155
  • uint256 The amount of the ERC1155 to transfer

FOUNDATION​

  • uint256 The ETH value to forward to the Foundation contract
  • bytes The calldata to use to call the Foundation contract
  • address The recipient of the ERC721
  • address The ERC721 token address
  • uint256 The ID of the ERC721

SWEEP_ERC1155​

  • address The ERC1155 token address to sweep
  • address The recipient of the sweep
  • uint256 The token ID to sweep
  • uint256 The minimum required tokens to receive from the sweep

Example: Reverting Commands​

For a Sudoswap command, that should be allowed to revert, the following 8 bit command should be provided:

command = 0x80 (10000000) && 0x19 (00011001) = 0x99 (10011001)

Take care when working with reverting commands - ensure you have appended commands to deal with funds that could remain in the contract after either outcomes. For example, if the Sudoswap command reverts, a following SWEEP can be added to ensure that any ETH that was not spent does not get left in the router.

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