com.facebook.presto.jdbc.internal.guava.hash.MacHashFunction Maven / Gradle / Ivy
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/*
* Copyright (C) 2015 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package com.facebook.presto.jdbc.internal.guava.hash;
import static com.facebook.presto.jdbc.internal.guava.base.Preconditions.checkNotNull;
import static com.facebook.presto.jdbc.internal.guava.base.Preconditions.checkState;
import com.google.errorprone.annotations.Immutable;
import java.nio.ByteBuffer;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import javax.crypto.Mac;
/**
* {@link HashFunction} adapter for {@link Mac} instances.
*
* @author Kurt Alfred Kluever
*/
@Immutable
@ElementTypesAreNonnullByDefault
final class MacHashFunction extends AbstractHashFunction {
@SuppressWarnings("Immutable") // cloned before each use
private final Mac prototype;
@SuppressWarnings("Immutable") // keys are immutable, but not provably so
private final Key key;
private final String toString;
private final int bits;
private final boolean supportsClone;
MacHashFunction(String algorithmName, Key key, String toString) {
this.prototype = getMac(algorithmName, key);
this.key = checkNotNull(key);
this.toString = checkNotNull(toString);
this.bits = prototype.getMacLength() * Byte.SIZE;
this.supportsClone = supportsClone(prototype);
}
@Override
public int bits() {
return bits;
}
private static boolean supportsClone(Mac mac) {
try {
Object unused = mac.clone();
return true;
} catch (CloneNotSupportedException e) {
return false;
}
}
private static Mac getMac(String algorithmName, Key key) {
try {
Mac mac = Mac.getInstance(algorithmName);
mac.init(key);
return mac;
} catch (NoSuchAlgorithmException e) {
throw new IllegalStateException(e);
} catch (InvalidKeyException e) {
throw new IllegalArgumentException(e);
}
}
@Override
public Hasher newHasher() {
if (supportsClone) {
try {
return new MacHasher((Mac) prototype.clone());
} catch (CloneNotSupportedException e) {
// falls through
}
}
return new MacHasher(getMac(prototype.getAlgorithm(), key));
}
@Override
public String toString() {
return toString;
}
/** Hasher that updates a {@link Mac} (message authentication code). */
private static final class MacHasher extends AbstractByteHasher {
private final Mac mac;
private boolean done;
private MacHasher(Mac mac) {
this.mac = mac;
}
@Override
protected void update(byte b) {
checkNotDone();
mac.update(b);
}
@Override
protected void update(byte[] b) {
checkNotDone();
mac.update(b);
}
@Override
protected void update(byte[] b, int off, int len) {
checkNotDone();
mac.update(b, off, len);
}
@Override
protected void update(ByteBuffer bytes) {
checkNotDone();
checkNotNull(bytes);
mac.update(bytes);
}
private void checkNotDone() {
checkState(!done, "Cannot re-use a Hasher after calling hash() on it");
}
@Override
public HashCode hash() {
checkNotDone();
done = true;
return HashCode.fromBytesNoCopy(mac.doFinal());
}
}
}
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