DataHaven Native Transfer Pallet

A Substrate pallet that enables cross-chain transfers of DataHaven native tokens to and from Ethereum using the Snowbridge infrastructure.

Overview

This pallet facilitates the transfer of DataHaven (DH) native tokens to Ethereum, where they are represented as wrapped ERC20 tokens. It implements a lock-and-mint mechanism: tokens are locked on DataHaven when transferred to Ethereum, and unlocked when transferred back.

Features

• Cross-chain Transfers: Transfer DH tokens to Ethereum addresses
• Token Locking: Secure token locking in a sovereign account during transfers
• Fee Management: Mandatory fee collection for bridge relayers
• Pause Mechanism: Emergency pause functionality for security

Fee Structure

Fees are mandatory for all transfers and serve to:

1. Compensate relayers for Ethereum gas costs
2. Provide incentive for timely message delivery
3. Prevent spam transactions

The fee is:

• Collected in DataHaven native tokens
• Transferred to a designated fee recipient account
• Separate from the transfer amount

Fee Calculation Guidelines

When calculating fees, consider:

1. Ethereum Gas Costs: Estimate gas required for the Ethereum transaction
2. Gas Price: Current Ethereum gas prices (use oracles or fixed estimates)
3. Exchange Rate: DH to ETH conversion rate
4. Relayer Margin: Additional incentive

Example calculation:

Ethereum gas required: 100,000 gas
Gas price: 30 gwei
ETH cost: 0.003 ETH
DH/ETH rate: 1000 DH per ETH
Base fee: 3 DH
With 20% margin: 3.6 DH

Extrinsics

transfer_to_ethereum

Transfer DataHaven native tokens to an Ethereum address.

Parameters:

• origin: The account initiating the transfer
• recipient: The Ethereum address (H160) to receive the tokens
• amount: The amount of tokens to transfer
• fee: The fee to cover Ethereum gas costs and incentivize relayers (must be non-zero)

pause

Pause all transfers. Only callable by PauseOrigin (typically governance).

unpause

Resume transfers after pause. Only callable by PauseOrigin.

Public Functions

total_locked_balance

Get the total balance of tokens locked in the Ethereum sovereign account.

ethereum_sovereign_account

Get the account ID of the Ethereum sovereign account for monitoring purposes.

Events

• TokensLocked: Emitted when tokens are locked for transfer
• TokensUnlocked: Emitted when tokens are unlocked from Ethereum
• TokensTransferredToEthereum: Emitted on successful transfer to Ethereum
• Paused: Emitted when the pallet is paused
• Unpaused: Emitted when the pallet is unpaused

Errors

• InsufficientBalance: Account has insufficient balance for transfer
• Overflow: Arithmetic overflow in calculations
• SendMessageFailed: Failed to send message through Snowbridge
• InvalidEthereumAddress: Provided Ethereum address is zero
• InvalidAmount: Transfer amount is zero
• TransfersDisabled: Transfers are paused
• ZeroFee: Fee cannot be zero

Security Considerations

1. Pause Mechanism: The pallet can be paused by governance in case of emergencies
2. Fee Validation: All transfers require non-zero fees to prevent spam
3. Balance Preservation: The pallet uses Preservation::Preserve to maintain existential deposits
4. Address Validation: Zero Ethereum addresses are rejected