org.fisco.bcos.web3j.precompile.cns.NameHash Maven / Gradle / Ivy
package org.fisco.bcos.web3j.precompile.cns;
import org.fisco.bcos.web3j.crypto.Hash;
import org.fisco.bcos.web3j.utils.Numeric;
import java.net.IDN;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
/**
* 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);
}
}
}