Paying Teleporter fees with native tokens

[minghinmatthewlam]

Problem

Right now TeleporterMessenger only takes ERC20s as a fee, and none of the functions as marked as payable to allow for paying fees to relayers. This means that any apps built on top of Teleporter needs to handle fees through ERC20s, but often this can be an extra step for users to require an ERC20, and it needs to be an ERC20 that relayers will accept.

Proposal

Instead we should allow the option to pay with the native assets of the chain, but TeleporterMessenger has already gone through multiple audits and we want to avoid major changes to the contract right before launch. A separate wrapping contract would help handle this case, which takes in the native asset, converts into a standard ERC20 like WAVAX, then performs the subsequent call to Teleporter. This contract should supply the need for any Teleporter app to pay for Teleporter fees through the native assets of the chain, and still provide ERC20 tokens that will be desired by relayers for incentives.

I'm thinking to use a Solidity library, that way the msg.sender values will remain the same when depositing native asset for ERC20 token, and also can make the call to Teleporter to maintain the same msg.sender value. The library should include:

• Taking in the constructor a set ERC20 token standard to swap the native assets for, like WAVAX
• Function for converting native asset to ERC20 token and calling Teleporter:
  • Should have similar inputs as sendCrossChainMessage but no need for feeTokenAddress since we're using native asset
  • marked as payable
  • calls the ERC20 token's deposit() to get returned ERC20 token amount
  • calls Teleporter with all the other parameters

Questions

• Should the library just allow users to pass in a token address they want to convert to, or should it be fixed to one?
• Is this even worth a contract if it's really simple?
• Can this be used to set a standard of Teleporter apps that want to pay with native assets?

[minghinmatthewlam]

This will be tackled in issue #292