Add support for ENSIP-10

[hboon]

• [ ] ENSIP-10 [^1]
• [ ] Requires EIP3668 [^2] support

Relevant announcement: https://medium.com/the-ethereum-name-service/upgrade-ethers-js-to-5-6-1-to-activate-ens-l2-offchain-integration-40ee1a0fdf2a

I found the post from etherjs quite useful: https://blog.ricmoo.com/highlights-ethers-js-march-2022-f511fe1e88a1

0x41563129cDbbD0c5D3e1c86cf9563926b243834d

Sample data

offchainexample.eth -> 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
1.offchainexample.eth -> 0x41563129cdbbd0c5d3e1c86cf9563926b243834d//This relies on wildcard resolution support
2.offchainexample.eth -> 0x41563129cdbbd0c5d3e1c86cf9563926b243834d too //This relies on wildcard resolution support
ricmoose.hatch.eth -> error
hweeboon.eth -> 0xbbce83173d5c1D122AE64856b4Af0D5AE07Fa362

ENSIP-10

Key part of ENSIP-10 spec starts at:

If a resolver implements this function, it MUST return true when supportsInterface() is called on it with the interface's ID, 0x9061b923.

Pre-ENSIP-10:

resolver = ensContract.resolver(originalName)
address = resolver.addr(originalName)

With ENSIP-10 wildcard resolution:

name = originalName
while name.notEmpty
    resolver = ensContract.resolver(name)
    if resolver != 0x
        break //found it
    end
    name = parent(name) //`1.offchainexample.eth` -> `offchainexample.eth`
end
if resolver.supportsInterface("0x9061b923")
    dnsEncodedName = dnsEncode(originalName)
    calldata = addr's //as if calling resolver.addr()
    address = resolver.resolve(dnsEncodedName, calldata)
else
    address = resolver.addr(originalName)
end

The resolver.resolve(bytes,bytes) call is the one that might trigger EIP3668 with our test data.

EIP3668

This seems to add EIP3668 support to web3j:

The diagram at https://eips.ethereum.org/EIPS/eip-3668#overview describes the flow well. But basically, if a transaction call reverts with OffchainLookup(address,string[],bytes,bytes4,bytes) then we need to trigger EIP3668 support by:

1. parsing the OffchainLookup error
2. HTTP GET/POST against the gateway URL(s) specified in the OffchainLookup error
3. call the contract with the function specified with data from the gateway response + data extracted from the OffchainLookup error
4. result from (3) replaces the original smart contract call that triggered EIP3668

Step 3 might trigger EIP3668 again.

Pre-EIP3668 support:

func web3j.call(contract, func)
    return contract.func
end

With EIP3668 support:

func web3j.call(contract, func)
    result = contract.func
    if result == OffchainLookup
        //Trigger EIP3668
        urls, sender, callBack, callData, extraData = extract(offchainLookup)
        gatewayResult = httpGetOrPost(urls, sender, callData)
        return contract.callback(gatewayResult, extraData) //This could trigger EIP3668 again
    else
        return result
    end
end

I found etherjs's implementation great for understanding how to implement EIP3668. Look for the implementation of ccipReadFetch and where it is called: https://github.com/ethers-io/ethers.js/blob/bc400c7b87b03438abb2f9874ec136dbf7b6437c/packages/providers/src.ts/base-provider.ts#L854

iOS PRs for reference

• AlphaWallet iOS for ENSIP-10: https://github.com/AlphaWallet/alpha-wallet-ios/pull/4237
• web3Swift support EIP3668: https://github.com/AlphaWallet/web3swift/pull/10

[^1]: ENSIP-10 https://docs.ens.domains/ens-improvement-proposals/ensip-10-wildcard-resolution [^2]: EIP3668 https://eips.ethereum.org/EIPS/eip-3668#use-of-get-and-post-requests-for-the-gateway-interface

[hboon]

@JamesSmartCell I have updated the first comment because the addresses for these 2 aren't 0xb8c anymore:

1.offchainexample.eth -> 0xb8c2C29ee19D8307cb7255e1Cd9CbDE883A267d5 //This relies on wildcard resolution support
2.offchainexample.eth -> 0xb8c2C29ee19D8307cb7255e1Cd9CbDE883A267d5 too //This relies on wildcard resolution support