/*

 * Copyright (c) 2018, 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 sun.security.ssl;

import java.io.IOException;

import java.nio.ByteBuffer;

import java.text.MessageFormat;

import java.util.*;

import sun.security.ssl.SSLExtension.ExtensionConsumer;

import sun.security.ssl.SSLExtension.SSLExtensionSpec;

import sun.security.ssl.SSLHandshake.HandshakeMessage;

/**

 * Pack of the "psk_key_exchange_modes" extensions.

 */

final class PskKeyExchangeModesExtension {

    static final HandshakeProducer chNetworkProducer =

            new PskKeyExchangeModesProducer();

    static final ExtensionConsumer chOnLoadConsumer =

            new PskKeyExchangeModesConsumer();

    enum PskKeyExchangeMode {

        PSK_KE(0),

        PSK_DHE_KE(1);

        private final int v;

        PskKeyExchangeMode(int v) {

            this.v = v;

        }

        static PskKeyExchangeMode ofInt(int v) {

            for(PskKeyExchangeMode mode : values()) {

                if (mode.v == v) {

                    return mode;

                }

            }

            return null;

        }

    }

    static final class PskKeyExchangeModesSpec implements SSLExtensionSpec {

        final List<PskKeyExchangeMode> modes;

        PskKeyExchangeModesSpec(List<PskKeyExchangeMode> modes) {

            this.modes = modes;

        }

        PskKeyExchangeModesSpec(ByteBuffer m) throws IOException {

            modes = new ArrayList<>();

            int modesEncodedLength = Record.getInt8(m);

            int modesReadLength = 0;

            while (modesReadLength < modesEncodedLength) {

                int mode = Record.getInt8(m);

                // TODO: handle incorrect values

                modes.add(PskKeyExchangeMode.ofInt(mode));

                modesReadLength += 1;

            }

        }

        byte[] getEncoded() throws IOException {

            int encodedLength = modes.size() + 1;

            byte[] buffer = new byte[encodedLength];

            ByteBuffer m = ByteBuffer.wrap(buffer);

            Record.putInt8(m, modes.size());

            for(PskKeyExchangeMode curMode : modes) {

                Record.putInt8(m, curMode.v);

            }

            return buffer;

        }

        @Override

        public String toString() {

            MessageFormat messageFormat = new MessageFormat(

            "\"PskKeyExchangeModes\": '{'\n" +

            "  \"ke_modes\"      : \"{0}\",\n" +

            "'}'",

            Locale.ENGLISH);

            Object[] messageFields = {

            Utilities.indent(modesString()),

            };

            return messageFormat.format(messageFields);

        }

        String modesString() {

            StringBuilder result = new StringBuilder();

            for(PskKeyExchangeMode curMode : modes) {

                result.append(curMode.toString() + "\n");

            }

            return result.toString();

        }

    }

    private static final

            class PskKeyExchangeModesConsumer implements ExtensionConsumer {

        // Prevent instantiation of this class.

        private PskKeyExchangeModesConsumer() {

            // blank

        }

        @Override

        public void consume(ConnectionContext context,

            HandshakeMessage message, ByteBuffer buffer) throws IOException {

            ServerHandshakeContext shc =

                    (ServerHandshakeContext) message.handshakeContext;

            PskKeyExchangeModesSpec modes = new PskKeyExchangeModesSpec(buffer);

            if (SSLLogger.isOn && SSLLogger.isOn("ssl,handshake")) {

                SSLLogger.fine(

                "Received PskKeyExchangeModes extension: ", modes);

            }

            shc.pskKeyExchangeModes = modes.modes;

        }

    }

    private static final

            class PskKeyExchangeModesProducer implements HandshakeProducer {

        static final List<PskKeyExchangeMode> MODES =

            List.of(PskKeyExchangeMode.PSK_DHE_KE);

        static final PskKeyExchangeModesSpec MODES_MSG =

            new PskKeyExchangeModesSpec(MODES);

        // Prevent instantiation of this class.

        private PskKeyExchangeModesProducer() {

            // blank

        }

        @Override

        public byte[] produce(ConnectionContext context,

                HandshakeMessage message) throws IOException {

            return MODES_MSG.getEncoded();

        }

    }

}