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helix-bridge / contracts

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Consider adding a callback interface for _recipient in function issuexToken(..) #55

Closed hackfisher closed 4 months ago

hackfisher commented 7 months ago

https://github.com/helix-bridge/contracts/blob/fab321ee8af549074936c319afd959c9b64ba459/helix-contract/contracts/mapping-token/v3/base/xTokenIssuing.sol#L94-L101

Similar to https://docs.uniswap.org/contracts/v3/reference/core/interfaces/callback/IUniswapV3SwapCallback

Must use https://github.com/ethereum/ercs/blob/master/ERCS/erc-165.md

Normal contracts do NOT set this interface.

Use cases:

https://github.com/orgs/dcdao/discussions/89#discussioncomment-8474171

Supporting wrap to RING after issuing xRING directly, do not need further tx on target chain. implementing a callback contract implementing this interface and be set as the _recipient, and it will wrap_to() target address as RING after being called here. (How to estimate the gas? or giving a limited gas for the callback, can not exceed it.)

Security audit needed.

hackfisher commented 7 months ago

Again, the xtoken Issuing contact have special auth to some contacts such as mint/burn, so check interface like EIP165 is mandatory, carefully audit must be done, better to make the interface unique.

hackfisher commented 6 months ago

This is extensible as it make other use cases possible, e.g. the recipient call back could be a extension for users to swap tokens in dex like Uniswap. (But be carefully about MEV, and relayers should use rpcs like Flashbots to avoid MEV attacks.)

xiaoch05 commented 4 months ago

https://github.com/helix-bridge/contracts/pull/56