/*

 * Copyright (c) 2015, 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.nio.charset.StandardCharsets;

import java.util.Arrays;

import java.util.Collections;

import java.util.LinkedList;

import java.util.List;

import javax.net.ssl.SSLEngine;

import javax.net.ssl.SSLProtocolException;

import javax.net.ssl.SSLSocket;

import sun.security.ssl.SSLExtension.ExtensionConsumer;

import sun.security.ssl.SSLExtension.SSLExtensionSpec;

import sun.security.ssl.SSLHandshake.HandshakeMessage;

/**

 * Pack of the "application_layer_protocol_negotiation" extensions [RFC 7301].

 */

final class AlpnExtension {

    static final HandshakeProducer chNetworkProducer = new CHAlpnProducer();

    static final ExtensionConsumer chOnLoadConsumer = new CHAlpnConsumer();

    static final HandshakeAbsence chOnLoadAbsence = new CHAlpnAbsence();

    static final HandshakeProducer shNetworkProducer = new SHAlpnProducer();

    static final ExtensionConsumer shOnLoadConsumer = new SHAlpnConsumer();

    static final HandshakeAbsence shOnLoadAbsence = new SHAlpnAbsence();

    // Note: we reuse ServerHello operations for EncryptedExtensions for now.

    // Please be careful about any code or specification changes in the future.

    static final HandshakeProducer eeNetworkProducer = new SHAlpnProducer();

    static final ExtensionConsumer eeOnLoadConsumer = new SHAlpnConsumer();

    static final HandshakeAbsence eeOnLoadAbsence = new SHAlpnAbsence();

    static final SSLStringizer alpnStringizer = new AlpnStringizer();

    /**

     * The "application_layer_protocol_negotiation" extension.

     *

     * See RFC 7301 for the specification of this extension.

     */

    static final class AlpnSpec implements SSLExtensionSpec {

        final List<String> applicationProtocols;

        private AlpnSpec(String[] applicationProtocols) {

            this.applicationProtocols = Collections.unmodifiableList(

                    Arrays.asList(applicationProtocols));

        }

        private AlpnSpec(ByteBuffer buffer) throws IOException {

            // ProtocolName protocol_name_list<2..2^16-1>, RFC 7301.

            if (buffer.remaining() < 2) {

                throw new SSLProtocolException(

                    "Invalid application_layer_protocol_negotiation: " +

                    "insufficient data (length=" + buffer.remaining() + ")");

            }

            int listLen = Record.getInt16(buffer);

            if (listLen < 2 || listLen != buffer.remaining()) {

                throw new SSLProtocolException(

                    "Invalid application_layer_protocol_negotiation: " +

                    "incorrect list length (length=" + listLen + ")");

            }

            List<String> protocolNames = new LinkedList<>();

            while (buffer.hasRemaining()) {

                // opaque ProtocolName<1..2^8-1>, RFC 7301.

                byte[] bytes = Record.getBytes8(buffer);

                if (bytes.length == 0) {

                    throw new SSLProtocolException(

                        "Invalid application_layer_protocol_negotiation " +

                        "extension: empty application protocol name");

                }

                String appProtocol = new String(bytes, StandardCharsets.UTF_8);

                protocolNames.add(appProtocol);

            }

            this.applicationProtocols =

                    Collections.unmodifiableList(protocolNames);

        }

        @Override

        public String toString() {

            return applicationProtocols.toString();

        }

    }

    private static final class AlpnStringizer implements SSLStringizer {

        @Override

        public String toString(ByteBuffer buffer) {

            try {

                return (new AlpnSpec(buffer)).toString();

            } catch (IOException ioe) {

                // For debug logging only, so please swallow exceptions.

                return ioe.getMessage();

            }

        }

    }

    /**

     * Network data producer of the extension in a ClientHello

     * handshake message.

     */

    private static final class CHAlpnProducer implements HandshakeProducer {

        static final int MAX_AP_LENGTH = 255;

        static final int MAX_AP_LIST_LENGTH = 65535;

        // Prevent instantiation of this class.

        private CHAlpnProducer() {

            // blank

        }

        @Override

        public byte[] produce(ConnectionContext context,

                HandshakeMessage message) throws IOException {

            // The producing happens in client side only.

            ClientHandshakeContext chc = (ClientHandshakeContext)context;

            // Is it a supported and enabled extension?

            if (!chc.sslConfig.isAvailable(SSLExtension.CH_ALPN)) {

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

                    SSLLogger.info(

                            "Ignore client unavailable extension: " +

                            SSLExtension.CH_ALPN.name);

                }

                chc.applicationProtocol = "";

                chc.conContext.applicationProtocol = "";

                return null;

            }

            String[] laps = chc.sslConfig.applicationProtocols;

            if ((laps == null) || (laps.length == 0)) {

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

                    SSLLogger.info(

                            "No available application protocols");

                }

                return null;

            }

            // Produce the extension.

            int listLength = 0;     // ProtocolNameList length

            for (String ap : laps) {

                int length = ap.getBytes(StandardCharsets.UTF_8).length;

                if (length == 0) {

                    // log the configuration problem

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

                        SSLLogger.severe(

                                "Application protocol name cannot be empty");

                    }

                            "Application protocol name cannot be empty");

                }

                if (length <= MAX_AP_LENGTH) {

                    // opaque ProtocolName<1..2^8-1>, RFC 7301.

                    listLength += (length + 1);

                } else {

                    // log the configuration problem

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

                        SSLLogger.severe(

                                "Application protocol name (" + ap +

                                ") exceeds the size limit (" +

                                MAX_AP_LENGTH + " bytes)");

                    }

                                "Application protocol name (" + ap +

                                ") exceeds the size limit (" +

                                MAX_AP_LENGTH + " bytes)");

                }

                if (listLength > MAX_AP_LIST_LENGTH) {

                    // log the configuration problem

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

                        SSLLogger.severe(

                                "The configured application protocols (" +

                                Arrays.toString(laps) +

                                ") exceed the size limit (" +

                                MAX_AP_LIST_LENGTH + " bytes)");

                    }

                                "The configured application protocols (" +

                                Arrays.toString(laps) +

                                ") exceed the size limit (" +

                                MAX_AP_LIST_LENGTH + " bytes)");

                }

            }

            // ProtocolName protocol_name_list<2..2^16-1>, RFC 7301.

            byte[] extData = new byte[listLength + 2];

            ByteBuffer m = ByteBuffer.wrap(extData);

            Record.putInt16(m, listLength);

            for (String ap : laps) {

                Record.putBytes8(m, ap.getBytes(StandardCharsets.UTF_8));

            }

            // Update the context.

            chc.handshakeExtensions.put(SSLExtension.CH_ALPN,

                    new AlpnSpec(chc.sslConfig.applicationProtocols));

            return extData;

        }

    }

    /**

     * Network data consumer of the extension in a ClientHello

     * handshake message.

     */

    private static final class CHAlpnConsumer implements ExtensionConsumer {

        // Prevent instantiation of this class.

        private CHAlpnConsumer() {

            // blank

        }

        @Override

        public void consume(ConnectionContext context,

            HandshakeMessage message, ByteBuffer buffer) throws IOException {

            // The consuming happens in server side only.

            ServerHandshakeContext shc = (ServerHandshakeContext)context;

            // Is it a supported and enabled extension?

            if (!shc.sslConfig.isAvailable(SSLExtension.CH_ALPN)) {

                shc.applicationProtocol = "";

                shc.conContext.applicationProtocol = "";

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

                    SSLLogger.info(

                            "Ignore server unavailable extension: " +

                            SSLExtension.CH_ALPN.name);

                }

                return;     // ignore the extension

            }

            // Is the extension enabled?

            boolean noAPSelector;

            if (shc.conContext.transport instanceof SSLEngine) {

                noAPSelector = (shc.sslConfig.engineAPSelector == null);

            } else {

                noAPSelector = (shc.sslConfig.socketAPSelector == null);

            }

            boolean noAlpnProtocols =

                    shc.sslConfig.applicationProtocols == null ||

                    shc.sslConfig.applicationProtocols.length == 0;

            if (noAPSelector && noAlpnProtocols) {

                shc.applicationProtocol = "";

                shc.conContext.applicationProtocol = "";

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

                    SSLLogger.fine(

                            "Ignore server unenabled extension: " +

                            SSLExtension.CH_ALPN.name);

                }

                return;     // ignore the extension

            }

            // Parse the extension.

            AlpnSpec spec;

            try {

                spec = new AlpnSpec(buffer);

            } catch (IOException ioe) {

            }

            // Update the context.

            if (noAPSelector) {     // noAlpnProtocols is false

                List<String> protocolNames = spec.applicationProtocols;

                boolean matched = false;

                // Use server application protocol preference order.

                for (String ap : shc.sslConfig.applicationProtocols) {

                    if (protocolNames.contains(ap)) {

                        shc.applicationProtocol = ap;

                        shc.conContext.applicationProtocol = ap;

                        matched = true;

                        break;

                    }

                }

                if (!matched) {

                            "No matching application layer protocol values");

                }

            }   // Otherwise, applicationProtocol will be set by the

                // application selector callback later.

            shc.handshakeExtensions.put(SSLExtension.CH_ALPN, spec);

            // No impact on session resumption.

            //

            // [RFC 7301] Unlike many other TLS extensions, this extension

            // does not establish properties of the session, only of the

            // connection.  When session resumption or session tickets are

            // used, the previous contents of this extension are irrelevant,

            // and only the values in the new handshake messages are

            // considered.

        }

    }

    /**

     * The absence processing if the extension is not present in

     * a ClientHello handshake message.

     */

    private static final class CHAlpnAbsence implements HandshakeAbsence {

        @Override

        public void absent(ConnectionContext context,

                HandshakeMessage message) throws IOException {

            // The producing happens in server side only.

            ServerHandshakeContext shc = (ServerHandshakeContext)context;

            // Please don't use the previous negotiated application protocol.

            shc.applicationProtocol = "";

            shc.conContext.applicationProtocol = "";

        }

    }

    /**

     * Network data producer of the extension in the ServerHello

     * handshake message.

     */

    private static final class SHAlpnProducer implements HandshakeProducer {

        // Prevent instantiation of this class.

        private SHAlpnProducer() {

            // blank

        }

        @Override

        public byte[] produce(ConnectionContext context,

                HandshakeMessage message) throws IOException {

            // The producing happens in client side only.

            ServerHandshakeContext shc = (ServerHandshakeContext)context;

            // In response to ALPN request only

            AlpnSpec requestedAlps =

                    (AlpnSpec)shc.handshakeExtensions.get(SSLExtension.CH_ALPN);

            if (requestedAlps == null) {

                // Ignore, this extension was not requested and accepted.

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

                    SSLLogger.fine(

                            "Ignore unavailable extension: " +

                            SSLExtension.SH_ALPN.name);

                }

                shc.applicationProtocol = "";

                shc.conContext.applicationProtocol = "";

                return null;

            }

            List<String> alps = requestedAlps.applicationProtocols;

            if (shc.conContext.transport instanceof SSLEngine) {

                if (shc.sslConfig.engineAPSelector != null) {

                    SSLEngine engine = (SSLEngine)shc.conContext.transport;

                    shc.applicationProtocol =

                        shc.sslConfig.engineAPSelector.apply(engine, alps);

                    if ((shc.applicationProtocol == null) ||

                            (!shc.applicationProtocol.isEmpty() &&

                            !alps.contains(shc.applicationProtocol))) {

                            "No matching application layer protocol values");

                    }

                }

            } else {

                if (shc.sslConfig.socketAPSelector != null) {

                    SSLSocket socket = (SSLSocket)shc.conContext.transport;

                    shc.applicationProtocol =

                        shc.sslConfig.socketAPSelector.apply(socket, alps);

                    if ((shc.applicationProtocol == null) ||

                            (!shc.applicationProtocol.isEmpty() &&

                            !alps.contains(shc.applicationProtocol))) {

                            "No matching application layer protocol values");

                    }

                }

            }

            if ((shc.applicationProtocol == null) ||

                    (shc.applicationProtocol.isEmpty())) {

                // Ignore, no negotiated application layer protocol.

                shc.applicationProtocol = "";

                shc.conContext.applicationProtocol = "";

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

                    SSLLogger.warning(

                        "Ignore, no negotiated application layer protocol");

                }

                return null;

            }

            // opaque ProtocolName<1..2^8-1>, RFC 7301.

            int listLen = shc.applicationProtocol.length() + 1;

                                                        // 1: length byte

            // ProtocolName protocol_name_list<2..2^16-1>, RFC 7301.

            byte[] extData = new byte[listLen + 2];     // 2: list length

            ByteBuffer m = ByteBuffer.wrap(extData);

            Record.putInt16(m, listLen);

            Record.putBytes8(m,

                    shc.applicationProtocol.getBytes(StandardCharsets.UTF_8));

            // Update the context.

            shc.conContext.applicationProtocol = shc.applicationProtocol;

            // Clean or register the extension

            //

            // No further use of the request and respond extension any more.

            shc.handshakeExtensions.remove(SSLExtension.CH_ALPN);

            return extData;

        }

    }

    /**

     * Network data consumer of the extension in the ServerHello

     * handshake message.

     */

    private static final class SHAlpnConsumer implements ExtensionConsumer {

        // Prevent instantiation of this class.

        private SHAlpnConsumer() {

            // blank

        }

        @Override

        public void consume(ConnectionContext context,

            HandshakeMessage message, ByteBuffer buffer) throws IOException {

            // The producing happens in client side only.

            ClientHandshakeContext chc = (ClientHandshakeContext)context;

            // In response to ALPN request only

            AlpnSpec requestedAlps =

                    (AlpnSpec)chc.handshakeExtensions.get(SSLExtension.CH_ALPN);

            if (requestedAlps == null ||

                    requestedAlps.applicationProtocols == null ||

                    requestedAlps.applicationProtocols.isEmpty()) {

                    "Unexpected " + SSLExtension.CH_ALPN.name + " extension");

            }

            // Parse the extension.

            AlpnSpec spec;

            try {

                spec = new AlpnSpec(buffer);

            } catch (IOException ioe) {

            }

            // Only one application protocol is allowed.

            if (spec.applicationProtocols.size() != 1) {

                    "Invalid " + SSLExtension.CH_ALPN.name + " extension: " +

                    "Only one application protocol name " +

                    "is allowed in ServerHello message");

            }

            // The respond application protocol must be one of the requested.

            if (!requestedAlps.applicationProtocols.containsAll(

                    spec.applicationProtocols)) {

                    "Invalid " + SSLExtension.CH_ALPN.name + " extension: " +

                    "Only client specified application protocol " +

                    "is allowed in ServerHello message");

            }

            // Update the context.

            chc.applicationProtocol = spec.applicationProtocols.get(0);

            chc.conContext.applicationProtocol = chc.applicationProtocol;

            // Clean or register the extension

            //