Resolving domain records

Resolving a domain is a process of retrieving a domain's records when the domain name and required record names are given. There is no limitation on who can read domain records on the Registry side. Anyone having access to the Ethereum Node on the mainnet can resolve a domain.

This section describes resolving domain records with making calls to Ethereum smart contracts, using Ethereum JSON RPC. For developers, who are interested in a more high-level solution, it might be more convenient to use resolution libraries instead. See the list of resolution libraries supported by the Unstoppable team.

Resolving a domain requires software to have access to the Ethereum network. For more information, see Configuring Ethereum Network connection.

The simplest way to resolve a domain with Ethereum JSON RPC is to make a read-only call to ProxyReader smart contract. ProxyReader provides an API that allows users to resolve domains making just one call, passing only keys of records and a domain namehash. Without ProxyReader it would require executing at least two calls: one to obtain a domain resolver address and another one to get the records themselves. With ProxyReader it all happens under the hood.

An example in JavaScript of getting two records (using ethers library):

const proxyReaderAddress = '0x7ea9Ee21077F84339eDa9C80048ec6db678642B1';
// Partial ABI, just for the getMany function.
const proxyReaderAbi = [
'function getMany(string[] calldata keys, uint256 tokenId) external view returns (string[] memory)'
];
const proxyReaderContract = new ethers.Contract(
proxyReaderAddress,
proxyReaderAbi,
provider,
);
const domain = 'brad.crypto';
const tokenId = namehash(domain);
const keys = ['crypto.ETH.address', 'crypto.BTC.address'];
const values = await proxyReaderContract.getMany(keys, tokenId);
console.log(values);
// [
// '0x8aaD44321A86b170879d7A244c1e8d360c99DdA8',
// 'bc1q359khn0phg58xgezyqsuuaha28zkwx047c0c3y'
// ]

Reference:

  • namehash - namehashing algorithm implementation. See Namehashing.

See Records reference for more information about the standardized records.

Record value validation

Crypto resolver doesn't have any built-in record value validation when it is updated for two reasons:

  • Any validation would require additional gas to be paid

  • Solidity is a special-purpose programming language that doesn't have any built-in data validation tools like Regular Expressions

Any domain management application must perform record format validation before submitting a transaction. However, there is no guarantee that all management applications will do it correctly. That is why records must be validated when the domain is resolved too.

See Records reference for more information for the validator of each record.

Configuring Ethereum network connection

Domain resolution configuration at a low level requires 3 configuration parameters:

  1. Ethereum JSON RPC provider

  2. Ethereum CHAIN ID

  3. Crypto Registry Contract Address

Ethereum JSON RPC provider is an API implementing the Ethereum JSON RPC standard. Usually, it is given in a form of an HTTP API endpoint. However, other forms may exist in the case when the Ethereum node is launched locally. Unstoppable Domains recommends Cloudflare Ethereum Gateway an Ethereum node service provider.

Ethereum CHAIN ID is an ID of the Ethereum network a node is connected to. Each RPC provider can only be connected to one network. There is only one production network with CHAIN ID equal to 1 and called mainnet. Other networks are only used for testing purposes of different kinds. See EIP-155 for more information. CHAIN ID of an Ethereum node can be determined by calling the net version method on JSON RPC which should be used as a default when only JSON RPC provider is given.

Crypto Registry Contract Address is an actual address of a contract deployed. There is only one production registry address on the mainnet: 0xD1E5b0FF1287aA9f9A268759062E4Ab08b9Dacbe. This address should be used as a default for production configuration.