/*

 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package com.oracle.security.ucrypto;

import java.lang.ref.*;

import java.io.ByteArrayOutputStream;

import java.util.*;

import java.util.concurrent.ConcurrentSkipListSet;

import java.security.*;

/**

 * MessageDigest implementation class for libMD API. This class currently supports

 * MD5, SHA1, SHA256, SHA384, and SHA512

 *

 * @since 9

 */

public abstract class NativeDigestMD extends MessageDigestSpi

        implements Cloneable {

    private static final int MECH_MD5 = 1;

    private static final int MECH_SHA1 = 2;

    private static final int MECH_SHA256 = 3;

    private static final int MECH_SHA224 = 4;

    private static final int MECH_SHA384 = 5;

    private static final int MECH_SHA512 = 6;

    private final int digestLen;

    private final int mech;

    // field for ensuring native memory is freed

    private DigestContextRef pCtxt = null;

    private static class DigestContextRef extends PhantomReference<NativeDigestMD>

        implements Comparable<DigestContextRef> {

        private static ReferenceQueue<NativeDigestMD> refQueue =

            new ReferenceQueue<NativeDigestMD>();

        // Needed to keep these references from being GC'ed until when their

        // referents are GC'ed so we can do post-mortem processing

        private static Set<DigestContextRef> refList =

            new ConcurrentSkipListSet<DigestContextRef>();

            //            Collections.synchronizedSortedSet(new TreeSet<DigestContextRef>());

        private final long id;

        private final int mech;

        private static void drainRefQueueBounded() {

            while (true) {

                DigestContextRef next = (DigestContextRef) refQueue.poll();

                if (next == null) break;

                next.dispose(true);

            }

        }

        DigestContextRef(NativeDigestMD nc, long id, int mech) {

            super(nc, refQueue);

            this.id = id;

            this.mech = mech;

            refList.add(this);

            UcryptoProvider.debug("Resource: track Digest Ctxt " + this.id);

            drainRefQueueBounded();

        }

        public int compareTo(DigestContextRef other) {

            if (this.id == other.id) {

                return 0;

            } else {

                return (this.id < other.id) ? -1 : 1;

            }

        }

        void dispose(boolean needFree) {

            refList.remove(this);

            try {

                if (needFree) {

                    UcryptoProvider.debug("Resource: free Digest Ctxt " + this.id);

                    NativeDigestMD.nativeFree(mech, id);

                } else UcryptoProvider.debug("Resource: stop tracking Digest Ctxt " + this.id);

            } finally {

                this.clear();

            }

        }

    }

    NativeDigestMD(int mech, int digestLen) {

        this.digestLen = digestLen;

        this.mech = mech;

    }

    // see JCA spec

    protected int engineGetDigestLength() {

        return digestLen;

    }

    // see JCA spec

    protected synchronized void engineReset() {

        if (pCtxt != null) {

            pCtxt.dispose(true);

            pCtxt = null;

        }

    }

    // see JCA spec

    protected synchronized byte[] engineDigest() {

        byte[] digest = new byte[digestLen];

        try {

            int len = engineDigest(digest, 0, digestLen);

            if (len != digestLen) {

                throw new UcryptoException("Digest length mismatch." +

                    " Len: " + len + ". digestLen: " + digestLen);

            }

            return digest;

        } catch (DigestException de) {

            throw new UcryptoException("Internal error", de);

        }

    }

    // see JCA spec

    protected synchronized int engineDigest(byte[] out, int ofs, int len)

            throws DigestException {

        if (len < digestLen) {

            throw new DigestException("Output buffer must be at least " +

                          digestLen + " bytes long. Got: " + len);

        }

        if ((ofs < 0) || (len < 0) || (ofs > out.length - len)) {

            throw new DigestException("Buffer too short to store digest. " +

                "ofs: " + ofs + ". len: " + len + ". out.length: " + out.length);

        }

        if (pCtxt == null) {

            pCtxt = new DigestContextRef(this, nativeInit(mech), mech);

        }

        try {

            int status = nativeDigest(mech, pCtxt.id, out, ofs, digestLen);

            if (status != 0) {

                throw new DigestException("Internal error: " + status);

            }

        } finally {

            pCtxt.dispose(false);

            pCtxt = null;

        }

        return digestLen;

    }

    // see JCA spec

    protected synchronized void engineUpdate(byte in) {

        byte[] temp = { in };

        engineUpdate(temp, 0, 1);

    }

    // see JCA spec

    protected synchronized void engineUpdate(byte[] in, int ofs, int len) {

        if (len == 0) {

            return;

        }

        if ((ofs < 0) || (len < 0) || (ofs > in.length - len)) {

            throw new ArrayIndexOutOfBoundsException("ofs: " + ofs + ". len: "

                + len + ". in.length: " + in.length);

        }

        if (pCtxt == null) {

            pCtxt = new DigestContextRef(this, nativeInit(mech), mech);

        }

        nativeUpdate(mech, pCtxt.id, in, ofs, len);

    }

    /**

     * Clone this digest.

     */

    public synchronized Object clone() throws CloneNotSupportedException {

        NativeDigestMD copy = (NativeDigestMD) super.clone();

        // re-work the fields that cannot be copied over

        if (pCtxt != null) {

            copy.pCtxt = new DigestContextRef(this, nativeClone(mech, pCtxt.id), mech);

        }

        return copy;

    }

    // return pointer to the context

    protected static final native long nativeInit(int mech);

    // return status code; always 0

    protected static final native int nativeUpdate(int mech, long pCtxt, byte[] in, int ofs, int inLen);

    // return status code; always 0

    protected static final native int nativeDigest(int mech, long pCtxt, byte[] out, int ofs, int digestLen);

    // return pointer to the duplicated context

    protected static final native long nativeClone(int mech, long pCtxt);

    // free the specified context

    private static final native void nativeFree(int mech, long id);

    public static final class MD5 extends NativeDigestMD {

        public MD5() {

            super(MECH_MD5, 16);

        }

    }

    public static final class SHA1 extends NativeDigestMD {

        public SHA1() {

            super(MECH_SHA1, 20);

        }

    }

    public static final class SHA256 extends NativeDigestMD {

        public SHA256() {

            super(MECH_SHA256, 32);

        }

    }

    public static final class SHA384 extends NativeDigestMD {

        public SHA384() {

            super(MECH_SHA384, 48);

        }

    }

    public static final class SHA512 extends NativeDigestMD {

        public SHA512() {

            super(MECH_SHA512, 64);

        }

    }

}