Add methods to support fetching the ENS contenthash and other record types

[moodysalem]

Currently there are no methods on the provider to support fetching and decoding contenthash, or other record types.

Specifically I need contenthash, but other methods are welcome

[ricmoo]

I completely agree, this is missing and should be added.

Simple methods, which do not require additional libraries will be added. So, the most common and simple content hashes (IPFS PB-node and Swarm) will be handled. Unsupported content hashes will throw an error.

For those following along at home, this is defined in EIP-1577. :)

[ricmoo]

I have local changes that support contenthash, text and multi-coin address support. Still needs more testing, but feels good so far. :)

[moodysalem]

Do these local changes also decode IPNS/IPFS content hashes?

[ricmoo]

It handles IPFS content hashes that use dag-pb formats. Are IPNS encoded CID different? If you have an example ENS name with an IPNS that would be super helpful. :)

I have made it super pessimistic though, so if it hits unsupported data, it will throw. It won't ever return wrong data. :)

[moodysalem]

The three formats we care about in Uniswap interface are:

• IPFS, e.g. ipfs://Qm..
• IPNS: ipns://Qm...
• IPNS + DNSLink: ipns://app.uniswap.org

Our decoding code in the interface is here:
https://github.com/Uniswap/uniswap-interface/blob/master/src/utils/contenthashToUri.ts#L21

And some example ENS names here:
https://github.com/Uniswap/uniswap-interface/blob/master/src/constants/lists.ts#L4

Our tokens.uniswap.eth ENS name points at ipns://tokens.uniswap.org

[ricmoo]

Right, but what about the binary encoding. Currently I only support CID version 1 (0x01) with the DAG-PB (0x70) type. It's more about the interpretation of the bytes.

I certainly do not support currently support IPNS + DNSLink... I've not seen that before... Do you have a link to docs?

I just tried all the ones in that test list and they all appear to by ipfs:// DAG-PB. I think you would need to have one with a type of 0xe5 to specify the identity tag, which would use IPNS. I don't support that right now, because I haven't found any usage of it yet to test against.

As people find unsupported combinations (the CID is quite complex) I'll expand support. However, like the multi-coin support, I only plan to support types that are either wildly popular or require very little additional code. To support all Multicodec formats (the vast majority of which probably do not have a single instance of existence on Earth) would more than double the size of the entire ethers.js library, which I aim to keep lean. :)

I might add the ability to extend the object though. So, for example, if you want ZCash support, you can register your own blake2b implementation. But that's a future idea. :)

I'll try getting it out today. :)

[ricmoo]

This should be available in 5.0.10.

You should be able to use:

const resolver = await provider.getResolver("ricmoo.eth");

// Content hash (supports IPFS and swarm; feel free to provide other examples to support)
const contentHash = await resolver.getContentHash();

// Multicoin support (more will be added as requested; assuming they are standard-is and popular)
const btcAddress = await resolver.getAddress(0);
const dogeAddress = await resolver.getAddress(3);

// Text records
const email = await resolver.getText("email");

Try it out and let me know how it goes. :)

[ricmoo]

Closing this now, but let me know if you have any issues.

Thanks! :)

[wuyuyue]

use the latest version 5.0.14 in my project which also need support ipns and cointype such as EOS, unfortunately, it is not working or needs some extra handle.
for details : blockchain-tools/ens-web-ext#1