/*
 * Copyright (c) 2003, 2012, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.security.pkcs11;

import java.util.*;
import java.nio.ByteBuffer;

import java.security.*;

import javax.crypto.SecretKey;

import sun.nio.ch.DirectBuffer;

import sun.security.pkcs11.wrapper.*;
import static sun.security.pkcs11.wrapper.PKCS11Constants.*;

MessageDigest implementation class. This class currently supports
MD2, MD5, SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512.
Note that many digest operations are on fairly small amounts of data
(less than 100 bytes total). For example, the 2nd hashing in HMAC or
the PRF in TLS. In order to speed those up, we use some buffering to
minimize number of the Java->native transitions.
Author:
 Andreas Sterbenz
Since:
  1.5/**
 * MessageDigest implementation class. This class currently supports
 * MD2, MD5, SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512.
 *
 * Note that many digest operations are on fairly small amounts of data
 * (less than 100 bytes total). For example, the 2nd hashing in HMAC or
 * the PRF in TLS. In order to speed those up, we use some buffering to
 * minimize number of the Java->native transitions.
 *
 * @author  Andreas Sterbenz
 * @since   1.5
 */
final class P11Digest extends MessageDigestSpi implements Cloneable {

    /* fields initialized, no session acquired */
    private final static int S_BLANK    = 1;

    /* data in buffer, session acquired, but digest not initialized */
    private final static int S_BUFFERED = 2;

    /* session initialized for digesting */
    private final static int S_INIT     = 3;

    private final static int BUFFER_SIZE = 96;

    // token instance
    private final Token token;

    // algorithm name
    private final String algorithm;

    // mechanism id object
    private final CK_MECHANISM mechanism;

    // length of the digest in bytes
    private final int digestLength;

    // associated session, if any
    private Session session;

    // current state, one of S_* above
    private int state;

    // buffer to reduce number of JNI calls
    private byte[] buffer;

    // offset into the buffer
    private int bufOfs;

    P11Digest(Token token, String algorithm, long mechanism) {
        super();
        this.token = token;
        this.algorithm = algorithm;
        this.mechanism = new CK_MECHANISM(mechanism);
        switch ((int)mechanism) {
        case (int)CKM_MD2:
        case (int)CKM_MD5:
            digestLength = 16;
            break;
        case (int)CKM_SHA_1:
            digestLength = 20;
            break;
        case (int)CKM_SHA224:
            digestLength = 28;
            break;
        case (int)CKM_SHA256:
            digestLength = 32;
            break;
        case (int)CKM_SHA384:
            digestLength = 48;
            break;
        case (int)CKM_SHA512:
            digestLength = 64;
            break;
        default:
            throw new ProviderException("Unknown mechanism: " + mechanism);
        }
        buffer = new byte[BUFFER_SIZE];
        state = S_BLANK;
    }

    // see JCA spec
    protected int engineGetDigestLength() {
        return digestLength;
    }

    private void fetchSession() {
        token.ensureValid();
        if (state == S_BLANK) {
            try {
                session = token.getOpSession();
                state = S_BUFFERED;
            } catch (PKCS11Exception e) {
                throw new ProviderException("No more session available", e);
            }
        }
    }

    // see JCA spec
    protected void engineReset() {
        token.ensureValid();

        if (session != null) {
            if (state == S_INIT && token.explicitCancel == true) {
                session = token.killSession(session);
            } else {
                session = token.releaseSession(session);
            }
        }
        state = S_BLANK;
        bufOfs = 0;
    }

    // see JCA spec
    protected byte[] engineDigest() {
        try {
            byte[] digest = new byte[digestLength];
            int n = engineDigest(digest, 0, digestLength);
            return digest;
        } catch (DigestException e) {
            throw new ProviderException("internal error", e);
        }
    }

    // see JCA spec
    protected int engineDigest(byte[] digest, int ofs, int len)
            throws DigestException {
        if (len < digestLength) {
            throw new DigestException("Length must be at least " +
                    digestLength);
        }

        fetchSession();
        try {
            int n;
            if (state == S_BUFFERED) {
                n = token.p11.C_DigestSingle(session.id(), mechanism, buffer, 0,
                        bufOfs, digest, ofs, len);
                bufOfs = 0;
            } else {
                if (bufOfs != 0) {
                    token.p11.C_DigestUpdate(session.id(), 0, buffer, 0,
                            bufOfs);
                    bufOfs = 0;
                }
                n = token.p11.C_DigestFinal(session.id(), digest, ofs, len);
            }
            if (n != digestLength) {
                throw new ProviderException("internal digest length error");
            }
            return n;
        } catch (PKCS11Exception e) {
            throw new ProviderException("digest() failed", e);
        } finally {
            engineReset();
        }
    }

    // see JCA spec
    protected void engineUpdate(byte in) {
        byte[] temp = { in };
        engineUpdate(temp, 0, 1);
    }

    // see JCA spec
    protected void engineUpdate(byte[] in, int ofs, int len) {
        if (len <= 0) {
            return;
        }

        fetchSession();
        try {
            if (state == S_BUFFERED) {
                token.p11.C_DigestInit(session.id(), mechanism);
                state = S_INIT;
            }
            if ((bufOfs != 0) && (bufOfs + len > buffer.length)) {
                // process the buffered data
                token.p11.C_DigestUpdate(session.id(), 0, buffer, 0, bufOfs);
                bufOfs = 0;
            }
            if (bufOfs + len > buffer.length) {
                // process the new data
                token.p11.C_DigestUpdate(session.id(), 0, in, ofs, len);
             } else {
                // buffer the new data
                System.arraycopy(in, ofs, buffer, bufOfs, len);
                bufOfs += len;
            }
        } catch (PKCS11Exception e) {
            engineReset();
            throw new ProviderException("update() failed", e);
        }
    }

    // Called by SunJSSE via reflection during the SSL 3.0 handshake if
    // the master secret is sensitive. We may want to consider making this
    // method public in a future release.
    protected void implUpdate(SecretKey key) throws InvalidKeyException {

        // SunJSSE calls this method only if the key does not have a RAW
        // encoding, i.e. if it is sensitive. Therefore, no point in calling
        // SecretKeyFactory to try to convert it. Just verify it ourselves.
        if (key instanceof P11Key == false) {
            throw new InvalidKeyException("Not a P11Key: " + key);
        }
        P11Key p11Key = (P11Key)key;
        if (p11Key.token != token) {
            throw new InvalidKeyException("Not a P11Key of this provider: " +
                    key);
        }

        fetchSession();
        try {
            if (state == S_BUFFERED) {
                token.p11.C_DigestInit(session.id(), mechanism);
                state = S_INIT;
            }

            if (bufOfs != 0) {
                token.p11.C_DigestUpdate(session.id(), 0, buffer, 0, bufOfs);
                bufOfs = 0;
            }
            token.p11.C_DigestKey(session.id(), p11Key.keyID);
        } catch (PKCS11Exception e) {
            engineReset();
            throw new ProviderException("update(SecretKey) failed", e);
        }
    }

    // see JCA spec
    protected void engineUpdate(ByteBuffer byteBuffer) {
        int len = byteBuffer.remaining();
        if (len <= 0) {
            return;
        }

        if (byteBuffer instanceof DirectBuffer == false) {
            super.engineUpdate(byteBuffer);
            return;
        }

        fetchSession();
        long addr = ((DirectBuffer)byteBuffer).address();
        int ofs = byteBuffer.position();
        try {
            if (state == S_BUFFERED) {
                token.p11.C_DigestInit(session.id(), mechanism);
                state = S_INIT;
            }
            if (bufOfs != 0) {
                token.p11.C_DigestUpdate(session.id(), 0, buffer, 0, bufOfs);
                bufOfs = 0;
            }
            token.p11.C_DigestUpdate(session.id(), addr + ofs, null, 0, len);
            byteBuffer.position(ofs + len);
        } catch (PKCS11Exception e) {
            engineReset();
            throw new ProviderException("update() failed", e);
        }
    }

    public Object clone() throws CloneNotSupportedException {
        P11Digest copy = (P11Digest) super.clone();
        copy.buffer = buffer.clone();
        try {
            if (session != null) {
                copy.session = copy.token.getOpSession();
            }
            if (state == S_INIT) {
                byte[] stateValues =
                    token.p11.C_GetOperationState(session.id());
                token.p11.C_SetOperationState(copy.session.id(),
                                              stateValues, 0, 0);
            }
        } catch (PKCS11Exception e) {
            throw (CloneNotSupportedException)
                (new CloneNotSupportedException(algorithm).initCause(e));
        }
        return copy;
    }
}