viem/actions/ens/getEnsResolver.ts

TypeScript Interface for Ethereum

import type { Address } from 'abitype'

import type { Client } from '../../clients/createClient.js'
import type { Transport } from '../../clients/transports/createTransport.js'
import type { ErrorType } from '../../errors/utils.js'
import type { Chain } from '../../types/chain.js'
import type { Prettify } from '../../types/utils.js'
import {
  type GetChainContractAddressErrorType,
  getChainContractAddress,
} from '../../utils/chain/getChainContractAddress.js'
import { type ToHexErrorType, toHex } from '../../utils/encoding/toHex.js'
import {
  type PacketToBytesErrorType,
  packetToBytes,
} from '../../utils/ens/packetToBytes.js'
import { getAction } from '../../utils/getAction.js'
import {
  type ReadContractParameters,
  readContract,
} from '../public/readContract.js'

export type GetEnsResolverParameters = Prettify<
  Pick<ReadContractParameters, 'blockNumber' | 'blockTag'> & {
    /** Name to get the address for. */
    name: string
    /** Address of ENS Universal Resolver Contract. */
    universalResolverAddress?: Address | undefined
  }
>

export type GetEnsResolverReturnType = Address

export type GetEnsResolverErrorType =
  | GetChainContractAddressErrorType
  | ToHexErrorType
  | PacketToBytesErrorType
  | ErrorType

/**
 * Gets resolver for ENS name.
 *
 * - Docs: https://viem.sh/docs/ens/actions/getEnsResolver
 * - Examples: https://stackblitz.com/github/wevm/viem/tree/main/examples/ens
 *
 * Calls `findResolver(bytes)` on ENS Universal Resolver Contract to retrieve the resolver of an ENS name.
 *
 * Since ENS names prohibit certain forbidden characters (e.g. underscore) and have other validation rules, you likely want to [normalize ENS names](https://docs.ens.domains/contract-api-reference/name-processing#normalising-names) with [UTS-46 normalization](https://unicode.org/reports/tr46) before passing them to `getEnsAddress`. You can use the built-in [`normalize`](https://viem.sh/docs/ens/utilities/normalize) function for this.
 *
 * @param client - Client to use
 * @param parameters - {@link GetEnsResolverParameters}
 * @returns Address for ENS resolver. {@link GetEnsResolverReturnType}
 *
 * @example
 * import { createPublicClient, http } from 'viem'
 * import { mainnet } from 'viem/chains'
 * import { getEnsResolver, normalize } from 'viem/ens'
 *
 * const client = createPublicClient({
 *   chain: mainnet,
 *   transport: http(),
 * })
 * const resolverAddress = await getEnsResolver(client, {
 *   name: normalize('wevm.eth'),
 * })
 * // '0x4976fb03C32e5B8cfe2b6cCB31c09Ba78EBaBa41'
 */
export async function getEnsResolver<chain extends Chain | undefined>(
  client: Client<Transport, chain>,
  parameters: GetEnsResolverParameters,
): Promise<GetEnsResolverReturnType> {
  const { blockNumber, blockTag, name } = parameters
  const { chain } = client

  const universalResolverAddress = (() => {
    if (parameters.universalResolverAddress)
      return parameters.universalResolverAddress
    if (!chain)
      throw new Error(
        'client chain not configured. universalResolverAddress is required.',
      )
    return getChainContractAddress({
      blockNumber,
      chain,
      contract: 'ensUniversalResolver',
    })
  })()

  const tlds = chain?.ensTlds
  if (tlds && !tlds.some((tld) => name.endsWith(tld)))
    throw new Error(
      `${name} is not a valid ENS TLD (${tlds?.join(', ')}) for chain "${chain.name}" (id: ${chain.id}).`,
    )

  const [resolverAddress] = await getAction(
    client,
    readContract,
    'readContract',
  )({
    address: universalResolverAddress,
    abi: [
      {
        inputs: [{ type: 'bytes' }],
        name: 'findResolver',
        outputs: [{ type: 'address' }, { type: 'bytes32' }],
        stateMutability: 'view',
        type: 'function',
      },
    ],
    functionName: 'findResolver',
    args: [toHex(packetToBytes(name))],
    blockNumber,
    blockTag,
  })
  return resolverAddress
}