DataHaven Native Transfer Precompile

This precompile exposes the pallet-datahaven-native-transfer functionality to the EVM layer, allowing smart contracts to transfer DataHaven native tokens to Ethereum via Snowbridge.

Overview

The DataHaven Native Transfer precompile provides an EVM-compatible interface for:

• Transferring native tokens from DataHaven to Ethereum
• Managing the pallet's operational state (pause/unpause)
• Querying transfer statistics and system state

Precompile Address: 0x0000000000000000000000000000000000000819 (2073 decimal)

Functions

transferToEthereum(address recipient, uint256 amount, uint256 fee)

Transfers DataHaven native tokens to an Ethereum address via Snowbridge.

Parameters:

• recipient: Ethereum address to receive the tokens
• amount: Amount of tokens to transfer (in smallest unit)
• fee: Fee to incentivize relayers (in smallest unit)

Requirements:

• Caller must have sufficient balance for amount + fee
• recipient cannot be the zero address
• amount and fee must be greater than zero
• Pallet must not be paused
• Native token must be registered on Ethereum

Example (Solidity):

import "./DataHavenNativeTransfer.sol";

contract MyContract {
    function sendToEthereum(address ethRecipient, uint256 amount) external {
        DATAHAVEN_NATIVE_TRANSFER_CONTRACT.transferToEthereum(
            ethRecipient,
            amount,
            100000000000000000 // 0.1 token fee
        );
    }
}

isPaused() view returns (bool)

Checks if the pallet is currently paused.

Returns:

• true if paused (transfers disabled)
• false if operational (transfers enabled)

Example (Solidity):

bool paused = DATAHAVEN_NATIVE_TRANSFER_CONTRACT.isPaused();
if (paused) {
    revert("Transfers are currently disabled");
}

totalLockedBalance() view returns (uint256)

Returns the total amount of tokens currently locked in the Ethereum sovereign account.

Returns:

• Total locked balance in smallest unit

Example (Solidity):

uint256 locked = DATAHAVEN_NATIVE_TRANSFER_CONTRACT.totalLockedBalance();

ethereumSovereignAccount() view returns (address)

Returns the address of the Ethereum sovereign account that holds locked tokens.

Returns:

• The sovereign account address

Example (Solidity):

address sovereign = DATAHAVEN_NATIVE_TRANSFER_CONTRACT.ethereumSovereignAccount();

Events

TokensLocked(address indexed account, uint256 amount)

Emitted when tokens are locked for transfer to Ethereum.

TokensUnlocked(address indexed account, uint256 amount)

Emitted when tokens are unlocked from Ethereum (handled by pallet, not directly through precompile).

TokensTransferredToEthereum(address indexed from, address indexed to, uint256 amount)

Emitted when a transfer to Ethereum is initiated.

Paused()

Emitted when the pallet is paused.

Unpaused()

Emitted when the pallet is unpaused.

Error Handling

The precompile provides detailed error messages for common failure cases:

• "Recipient cannot be zero address": The recipient parameter is the zero address
• "Amount must be greater than zero": The amount parameter is zero
• "Fee must be greater than zero": The fee parameter is zero
• "Amount overflow": The amount exceeds u128::MAX
• "Fee overflow": The fee exceeds u128::MAX
• "InsufficientBalance": Caller doesn't have enough tokens
• "TransfersDisabled": Pallet is paused
• "TokenNotRegistered": Native token not registered on Ethereum
• "BadOrigin": Caller doesn't have permission (for pause/unpause)

Gas Costs

Approximate gas costs for each operation:

Note: Actual gas costs may vary depending on runtime configuration and network conditions.

Integration Example

Complete example of integrating the precompile into a smart contract:

// SPDX-License-Identifier: GPL-3.0-only
pragma solidity ^0.8.0;

import "./DataHavenNativeTransfer.sol";

contract CrossChainBridge {
    event TransferInitiated(address indexed from, address indexed to, uint256 amount);
    
    function bridgeToEthereum(
        address ethRecipient,
        uint256 amount,
        uint256 fee
    ) external {
        require(!DATAHAVEN_NATIVE_TRANSFER_CONTRACT.isPaused(), "Transfers paused");
        require(ethRecipient != address(0), "Invalid recipient");
        require(amount > 0, "Invalid amount");
        
        DATAHAVEN_NATIVE_TRANSFER_CONTRACT.transferToEthereum(
            ethRecipient,
            amount,
            fee
        );
        
        emit TransferInitiated(msg.sender, ethRecipient, amount);
    }
    
    function getLockedBalance() external view returns (uint256) {
        return DATAHAVEN_NATIVE_TRANSFER_CONTRACT.totalLockedBalance();
    }
}

Testing

The precompile includes a comprehensive test suite covering:

• ✅ Function selector validation
• ✅ Function modifier checks
• ✅ Successful transfer scenarios
• ✅ Error cases (zero address, zero amount, insufficient balance, etc.)
• ✅ Pause/unpause functionality
• ✅ View function correctness
• ✅ Gas accounting
• ✅ Edge cases and overflow handling

Run tests with:

cd operator/precompiles/datahaven-native-transfer
cargo test

Security Considerations

1. Existential Deposit: Transfers respect the chain's existential deposit requirement. Ensure callers retain sufficient balance to keep their account alive.

2. Fee Payment: The fee is paid to the configured fee recipient separately from the amount being bridged. Ensure you have sufficient balance for both.

3. Token Registration: The native token must be registered on Ethereum before transfers can occur. Check this before initiating transfers.

4. Pause Mechanism: Only governance can pause the pallet. This is a safety mechanism for emergency situations.

5. Snowbridge Dependency: Transfers depend on the Snowbridge infrastructure. Monitor Snowbridge health before large transfers.

6. No Reentrancy: The precompile uses Frontier's reentrancy protection (forbid-evm-reentrancy feature).

Architecture

┌─────────────────┐
│  EVM Contract   │
└────────┬────────┘
         │ calls precompile at 0x...07F5
         ↓
┌─────────────────────────────┐
│ DataHavenNativeTransfer     │
│      Precompile             │
│  ┌──────────────────────┐   │
│  │ Address Mapping      │   │
│  │ Type Conversions     │   │
│  │ Gas Accounting       │   │
│  │ Error Handling       │   │
│  └──────────┬───────────┘   │
└─────────────┼───────────────┘
              │ dispatches call
              ↓
┌─────────────────────────────┐
│ pallet-datahaven-native-    │
│         transfer             │
│  ┌──────────────────────┐   │
│  │ Lock tokens          │   │
│  │ Build message        │   │
│  │ Send via Snowbridge  │   │
│  └──────────┬───────────┘   │
└─────────────┼───────────────┘
              │
              ↓
        [ Snowbridge ]
              │
              ↓
        [ Ethereum ]

Related Documentation

• Snowbridge Documentation
• Frontier Precompiles Guide
• DataHaven Native Transfer Pallet
• EVM-Substrate Integration

License

This precompile is part of DataHaven and is licensed under GPL-3.0.

Support

For issues or questions:

• GitHub Issues: datahaven repository
• Documentation: docs.datahaven.xyz