/*
 * Copyright (c) 2017, Red Hat, Inc. and/or its affiliates.
 * Copyright (c) 2018, 2022, 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.ssl;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Map;
import java.util.Random;

import javax.net.ssl.SSLProtocolException;
import static sun.security.ssl.SSLExtension.TLS_GREASE_0A0A;
import static sun.security.ssl.SSLExtension.TLS_GREASE_1A1A;
import static sun.security.ssl.SSLExtension.TLS_GREASE_2A2A;
import static sun.security.ssl.SSLExtension.TLS_GREASE_3A3A;
import static sun.security.ssl.SSLExtension.TLS_GREASE_4A4A;
import static sun.security.ssl.SSLExtension.TLS_GREASE_5A5A;
import static sun.security.ssl.SSLExtension.TLS_GREASE_6A6A;
import static sun.security.ssl.SSLExtension.TLS_GREASE_7A7A;
import static sun.security.ssl.SSLExtension.TLS_GREASE_8A8A;
import static sun.security.ssl.SSLExtension.TLS_GREASE_9A9A;
import static sun.security.ssl.SSLExtension.TLS_GREASE_AAAA;
import sun.security.ssl.SSLExtension.ExtensionConsumer;
import sun.security.ssl.SSLExtension.SSLExtensionSpec;
import sun.security.ssl.SSLHandshake.HandshakeMessage;

/**
 * Pack of the "TLS_GREASE" extensions [RFC 7627].
 */
final class TLSGreaseExtension {
    static final HandshakeProducer chNetworkProducer =
            new TLSGreaseProducer();
    static final ExtensionConsumer chOnLoadConsumer =
            new TLSGreaseConsumer();
    static final HandshakeAbsence chOnLoadAbsence =
            new TLSGreaseAbsence();

    static final SSLStringizer emsStringizer =
            new TLSGreaseStringizer();

    /**
     * The "TLS_GREASE" extension.
     */
    static final class TLSGreaseSpec implements SSLExtensionSpec {
        // A nominal object that does not hold any real renegotiation info.
        static final TLSGreaseSpec NOMINAL =
                new TLSGreaseSpec();

        private TLSGreaseSpec() {
            // blank
        }

        private TLSGreaseSpec(HandshakeContext hc,
                ByteBuffer m) throws IOException {
            // Parse the extension.
            if (m.hasRemaining()) {
                throw hc.conContext.fatal(Alert.DECODE_ERROR,
                        new SSLProtocolException(
                    "Invalid TLS_GREASE extension data: " +
                    "not empty"));
            }
        }

        @Override
        public String toString() {
            return "<empty>";
        }
    }

    private static final
            class TLSGreaseStringizer implements SSLStringizer {
        @Override
        public String toString(HandshakeContext hc, ByteBuffer buffer) {
            try {
                return (new TLSGreaseSpec(hc, buffer)).toString();
            } catch (IOException ioe) {
                // For debug logging only, so please swallow exceptions.
                return ioe.getMessage();
            }
        }
    }

    /**
     * Network data producer of an "TLS_GREASE" extension in
     * the ClientHello handshake message.
     */
    private static final
            class TLSGreaseProducer implements HandshakeProducer {
        // Prevent instantiation of this class.
        private TLSGreaseProducer() {
            // blank
        }

        @Override
        public byte[] produce(ConnectionContext context,
                HandshakeMessage message) throws IOException {
            // The producing happens in client side only.
            ClientHandshakeContext chc = (ClientHandshakeContext)context;

            chc.handshakeExtensions.put(TLS_GREASE_0A0A,
                TLSGreaseSpec.NOMINAL);

            byte[] extData = new byte[1];
            ByteBuffer m = ByteBuffer.wrap(extData);
            Record.putInt8(m, 0x0);
            return extData;
        }
    }

    /**
     * Network data producer of an "TLS_GREASE" extension in
     * the ServerHello handshake message.
     */
    private static final
            class TLSGreaseConsumer implements ExtensionConsumer {
        // Prevent instantiation of this class.
        private TLSGreaseConsumer() {
            // blank
        }

        @Override
        public void consume(ConnectionContext context,
            HandshakeMessage message, ByteBuffer buffer) throws IOException {

            // The consuming happens in server side only.
            ServerHandshakeContext shc = (ServerHandshakeContext)context;

            // Update the context.
            //
            shc.handshakeExtensions.put(
                TLS_GREASE_0A0A, TLSGreaseSpec.NOMINAL);

            // No impact on session resumption.
        }
    }

    /**
     * The absence processing if an "TLS_GREASE" extension is
     * not present in the ClientHello handshake message.
     */
    private static final
            class TLSGreaseAbsence implements HandshakeAbsence {
        @Override
        public void absent(ConnectionContext context,
                HandshakeMessage message) throws IOException {

        }
    }
}