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Supporting Meta Transactions

Rails Network Swap pool tokens facilitate meta-transaction approvals through the permit function, eliminating the requirement for a preliminary approve transaction for programmatic operations with the tokens.

ERC-712

Typical ERC-20 tokens necessitate that owners explicitly approve transactions through a function call that recognizes msg.sender as the approver. Meta-transaction approvals, however, are established through a signature provided to the function by the entity initiating the call, often known as the relayer. To handle the complexities of signing with Ethereum private keys, Rails Network Swap employs ERC-712, a widely recognized signature standard, ensuring compatibility and security across different wallets.

Domain Separator​

The domain separator is defined as follows:

keccak256(
  abi.encode(
    keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
    keccak256(bytes(name)),
    keccak256(bytes('1')),
    chainId,
    address(this)
  )
);
  • name corresponds to Uniswap V2, detailed in name.
  • chainId is 6278 for Mainnet and 24116 for Testnet
  • address(this) refers to the contract address of the pair, as outlined in Pair Addresses.

Permit Typehash​

The permit typehash is calculated with the following code:

keccak256('Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)');

This structure facilitates secure and efficient permissioning for meta-transactions within the Rails Network Swap ecosystem.