org.fisco.bcos.web3j.precompile.cns.NameHash Maven / Gradle / Ivy

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package org.fisco.bcos.web3j.precompile.cns;

import java.net.IDN;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import org.fisco.bcos.web3j.crypto.Hash;
import org.fisco.bcos.web3j.utils.Numeric;

/** ENS name hash implementation. */
public class NameHash {

  private static final byte[] EMPTY = new byte[32];

  public static byte[] nameHashAsBytes(String ensName) {
    return Numeric.hexStringToByteArray(nameHash(ensName));
  }

  public static String nameHash(String ensName) {
    String normalisedEnsName = normalise(ensName);
    return Numeric.toHexString(nameHash(normalisedEnsName.split("\\.")));
  }

  private static byte[] nameHash(String[] labels) {
    if (labels.length == 0 || labels[0].equals("")) {
      return EMPTY;
    } else {
      String[] tail;
      if (labels.length == 1) {
        tail = new String[] {};
      } else {
        tail = Arrays.copyOfRange(labels, 1, labels.length);
      }

      byte[] remainderHash = nameHash(tail);
      byte[] result = Arrays.copyOf(remainderHash, 64);

      byte[] labelHash = Hash.sha3(labels[0].getBytes(StandardCharsets.UTF_8));
      System.arraycopy(labelHash, 0, result, 32, labelHash.length);

      return Hash.sha3(result);
    }
  }

  /**
   * Normalise ENS name as per the specification.
   *
   * @param ensName our user input ENS name
   * @return normalised ens name
   * @throws CnsResolutionException if the name cannot be normalised
   */
  public static String normalise(String ensName) {
    try {
      return IDN.toASCII(ensName, IDN.USE_STD3_ASCII_RULES).toLowerCase();
    } catch (IllegalArgumentException e) {
      throw new CnsResolutionException("Invalid ENS name provided: " + ensName);
    }
  }
}