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Overview

The L1Unwrapper contract is an extension of the WETHOmnibridgeRouter that facilitates ETH deposits to the TornadoPool on L2 and handles withdrawals back to L1. It manages the wrapping/unwrapping of ETH to WETH for bridge compatibility and stores TornadoPool account registrations. Contract Location: contracts/bridge/L1Unwrapper.sol

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State Variables

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l1FeeReceiver
address payable
Address that receives L1 execution fees. If set to zero address, fees go to tx.origin. Can be changed by the multisig to implement fee sharing logic.

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Constructor

constructor(
  IOmnibridge _bridge,
  IWETH _weth,
  address _owner
)
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_bridge
IOmnibridge
required
OmniBridge contract address
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_weth
IWETH
required
Wrapped ETH (WETH) contract address
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_owner
address
required
Owner address for contract governance
Inherits from: WETHOmnibridgeRouter(_bridge, _weth, _owner) Source: contracts/bridge/L1Unwrapper.sol:37

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Public Functions

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register

function register(Account memory _account) public
Registers a user’s public key for the TornadoPool. This allows the user to receive shielded transfers.
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_account
Account
required
Account structure containing owner address and public key bytes
Requirements:
  • Account owner must be msg.sender
Emits: PublicKey(address indexed owner, bytes key) Source: contracts/bridge/L1Unwrapper.sol:46

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wrapAndRelayTokens

function wrapAndRelayTokens(
  address _receiver,
  bytes memory _data,
  Account memory _account
) public payable
Wraps native ETH to WETH and bridges it to L2, optionally registering an account in a single transaction. This is the main entry point for deposits from L1.
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_receiver
address
required
Receiver address on L2 (typically the TornadoPool contract)
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_data
bytes
required
Encoded data to pass to the receiver on L2 (contains Proof and ExtData)
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_account
Account
required
TornadoPool account data for registration. If account.owner == msg.sender, registration will occur.
Process:
  1. Wraps msg.value ETH to WETH
  2. Calls bridge.relayTokensAndCall() to send WETH and data to L2
  3. If _account.owner matches msg.sender, registers the account
Source: contracts/bridge/L1Unwrapper.sol:58

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onTokenBridged

function onTokenBridged(
  address _token,
  uint256 _value,
  bytes memory _data
) external override
Callback function invoked by OmniBridge when tokens are bridged from L2 to L1. Unwraps WETH to ETH and distributes to recipient with fee handling.
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_token
address
required
Bridged token address (must be WETH)
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_value
uint256
required
Amount of tokens bridged
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_data
bytes
required
Extra data containing recipient address and L1 fee (must be exactly 64 bytes)
Requirements:
  • Token must be WETH
  • Only callable by bridge contract
  • Data length must be exactly 64 bytes
Process:
  1. Withdraws WETH to native ETH
  2. Decodes recipient address and l1Fee from _data
  3. Sends (value - l1Fee) to recipient
  4. Sends l1Fee to l1FeeReceiver or tx.origin if l1FeeReceiver is zero address
Source: contracts/bridge/L1Unwrapper.sol:83

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setL1FeeReceiver

function setL1FeeReceiver(address payable _receiver) external
Sets the L1 fee receiver address. Only contract owner can call this method.
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_receiver
address payable
required
Address of the new L1 fee receiver. Set to address(0) for native tx.origin receiver.
Requirements:
  • Only callable by contract owner
Source: contracts/bridge/L1Unwrapper.sol:109

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Data Structures

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Account

struct Account {
  address owner;
  bytes publicKey;
}
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owner
address
Ethereum address of the account owner
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publicKey
bytes
Public key bytes for encryption and receiving shielded transfers (64 bytes: 32 bytes pubkey + 32 bytes encryption key)
Source: contracts/bridge/L1Unwrapper.sol:32

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Events

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PublicKey

event PublicKey(address indexed owner, bytes key)
Emitted when a user registers their public key.
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owner
address
Address of the account owner
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key
bytes
Public key bytes registered
Source: contracts/bridge/L1Unwrapper.sol:30

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Usage Example

const account = {
  owner: userAddress,
  publicKey: keypair.toString() // 64 bytes hex
}

const { args, extData } = await prepareTransaction({
  tornadoPool,
  outputs: [utxo1, utxo2],
  // ... other params
})

const data = ethers.utils.defaultAbiCoder.encode(
  ['tuple(bytes proof, bytes32 root, bytes32[] inputNullifiers, bytes32[2] outputCommitments, uint256 publicAmount, bytes32 extDataHash)', 'tuple(address recipient, int256 extAmount, address relayer, uint256 fee, bytes encryptedOutput1, bytes encryptedOutput2, bool isL1Withdrawal, uint256 l1Fee)'],
  [args, extData]
)

await l1Unwrapper.wrapAndRelayTokens(
  tornadoPoolAddress,
  data,
  account,
  { value: ethers.utils.parseEther('1.0') }
)

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Inherited Functions

L1Unwrapper inherits from WETHOmnibridgeRouter, which provides:
  • Bridge wrapping/unwrapping utilities
  • Owner access control via onlyOwner modifier
  • Safe ETH transfer helpers via AddressHelper.safeSendValue
See the OmniBridge documentation for additional inherited functionality.

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