Make ByteArrayWrapper safe for use as key in Map

The underlying byte[] is mutable and could accidentally be changed after
instantiation of the wrapper object. To ensure that the hashCode or the
(natural or fast) order of the object does not change, the data must be
copied defensively.

src/freenet/support/ByteArrayWrapper.java

@@ -12,31 +12,24 @@
  */
 public class ByteArrayWrapper implements Comparable<ByteArrayWrapper> {
 
-	private final byte[] buf;
-	private int hashCode;
+	private final byte[] data;
+	private final int hashCode;
 
-	public static final Comparator<ByteArrayWrapper> FAST_COMPARATOR = new Comparator<ByteArrayWrapper>() {
-
-		@Override
-		public int compare(ByteArrayWrapper o1, ByteArrayWrapper o2) {
-			if(o1.hashCode > o2.hashCode) return 1;
-			if(o1.hashCode < o2.hashCode) return -1;
-			return o1.compareTo(o2);
-		}
-
-	};
+	public static final Comparator<ByteArrayWrapper> FAST_COMPARATOR = Comparator
+			.comparingInt(ByteArrayWrapper::hashCode)
+			.thenComparing(Comparator.naturalOrder());
 
 	public ByteArrayWrapper(byte[] data) {
-		buf = data;
-		hashCode = Fields.hashCode(buf);
+		this.data = Arrays.copyOf(data, data.length);
+		this.hashCode = Arrays.hashCode(this.data);
 	}
 
 	@Override
-	public boolean equals(Object o) {
-		if(o instanceof ByteArrayWrapper) {
-			ByteArrayWrapper b = (ByteArrayWrapper) o;
-			if(b.buf == buf) return true;
-			return Arrays.equals(b.buf, buf);
+	public boolean equals(Object other) {
+		if (this == other) return true;
+		if (other instanceof ByteArrayWrapper) {
+			ByteArrayWrapper b = (ByteArrayWrapper) other;
+			return this.hashCode == b.hashCode && Arrays.equals(this.data, b.data);
 		}
 		return false;
 	}
@@ -46,14 +39,15 @@ public int hashCode() {
 		return hashCode;
 	}
 
-	/** DO NOT MODIFY THE RETURNED DATA! */
 	public byte[] get() {
-		return buf;
+		return Arrays.copyOf(data, data.length);
 	}
 
 	@Override
-	public int compareTo(ByteArrayWrapper arg) {
-		if(this == arg) return 0;
-		return Fields.compareBytes(buf, arg.buf);
+	public int compareTo(ByteArrayWrapper other) {
+		if (this == other) {
+			return 0;
+		}
+		return Fields.compareBytes(this.data, other.data);
 	}
 }