Bridge metadata trustlessly

[mfornet]

Bridge metadata of ERC20 tokens in a trustless way, so anyone can set metadata of bridged tokens.

Proposal:

Create a contract on Ethereum that implements:

struct Metadata {
        token: String,
        name: String,
        symbol: String,
        decimals: u8,
}

contract TellMetadata {
    fn get_metadata(token: address) {
        // fetch metadata from the token
        emit Metadata { .. }
    }
}

On NEAR side, the factory contains the address of this contract. This address is passed to each bridged token when it is deployed. BridgeToken should look like:

struct BridgeToken {
    ...,
    tell_metadata_address: EthereumAddress,
}

impl BridgeToken {
    ...,
    fn set_metadata(event: Vec<u8>, proof: Proof) {
        // Deserialize Metadata event
        // Check that it was emited by `TellMetadata`
        // Check that proof is valid
        // set metadata
    }
}