/*
 * Copyright (c) 2006, 2010, 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.io.PrintStream;
import java.util.*;

import java.security.spec.ECParameterSpec;
import java.security.spec.ECGenParameterSpec;
import java.security.spec.InvalidParameterSpecException;
import java.security.AlgorithmParameters;
import sun.security.util.AlgorithmConstraints;
import sun.security.util.CryptoPrimitive;
import java.security.AccessController;
import java.util.EnumSet;
import java.util.ArrayList;
import javax.net.ssl.SSLProtocolException;

import sun.security.action.GetPropertyAction;

This file contains all the classes relevant to TLS Extensions for the
ClientHello and ServerHello messages. The extension mechanism and
several extensions are defined in RFC 3546. Additional extensions are
defined in the ECC RFC 4492.
Currently, only the two ECC extensions are fully supported.
The classes contained in this file are:
 . HelloExtensions: a List of extensions as used in the client hello
     and server hello messages.
 . ExtensionType: an enum style class for the extension type
 . HelloExtension: abstract base class for all extensions. All subclasses
     must be immutable.
 . UnknownExtension: used to represent all parsed extensions that we do not
     explicitly support.
 . ServerNameExtension: partially implemented server_name extension.
 . SupportedEllipticCurvesExtension: the ECC supported curves extension.
 . SupportedEllipticPointFormatsExtension: the ECC supported point formats
     (compressed/uncompressed) extension.
Author:
 Andreas Sterbenz
Since:
  1.6/**
 * This file contains all the classes relevant to TLS Extensions for the
 * ClientHello and ServerHello messages. The extension mechanism and
 * several extensions are defined in RFC 3546. Additional extensions are
 * defined in the ECC RFC 4492.
 *
 * Currently, only the two ECC extensions are fully supported.
 *
 * The classes contained in this file are:
 *  . HelloExtensions: a List of extensions as used in the client hello
 *      and server hello messages.
 *  . ExtensionType: an enum style class for the extension type
 *  . HelloExtension: abstract base class for all extensions. All subclasses
 *      must be immutable.
 *
 *  . UnknownExtension: used to represent all parsed extensions that we do not
 *      explicitly support.
 *  . ServerNameExtension: partially implemented server_name extension.
 *  . SupportedEllipticCurvesExtension: the ECC supported curves extension.
 *  . SupportedEllipticPointFormatsExtension: the ECC supported point formats
 *      (compressed/uncompressed) extension.
 *
 * @since   1.6
 * @author  Andreas Sterbenz
 */
final class HelloExtensions {

    private List<HelloExtension> extensions;
    private int encodedLength;

    HelloExtensions() {
        extensions = Collections.emptyList();
    }

    HelloExtensions(HandshakeInStream s) throws IOException {
        int len = s.getInt16();
        extensions = new ArrayList<HelloExtension>();
        encodedLength = len + 2;
        while (len > 0) {
            int type = s.getInt16();
            int extlen = s.getInt16();
            ExtensionType extType = ExtensionType.get(type);
            HelloExtension extension;
            if (extType == ExtensionType.EXT_SERVER_NAME) {
                extension = new ServerNameExtension(s, extlen);
            } else if (extType == ExtensionType.EXT_ELLIPTIC_CURVES) {
                extension = new SupportedEllipticCurvesExtension(s, extlen);
            } else if (extType == ExtensionType.EXT_EC_POINT_FORMATS) {
                extension =
                        new SupportedEllipticPointFormatsExtension(s, extlen);
            } else if (extType == ExtensionType.EXT_RENEGOTIATION_INFO) {
                extension = new RenegotiationInfoExtension(s, extlen);
            } else if (extType == ExtensionType.EXT_EXTENDED_MASTER_SECRET) {
                extension = new ExtendedMasterSecretExtension(s, extlen);
            } else {
                extension = new UnknownExtension(s, extlen, extType);
            }
            extensions.add(extension);
            len -= extlen + 4;
        }
        if (len != 0) {
            throw new SSLProtocolException(
                        "Error parsing extensions: extra data");
        }
    }

    // Return the List of extensions. Must not be modified by the caller.
    List<HelloExtension> list() {
        return extensions;
    }

    void add(HelloExtension ext) {
        if (extensions.isEmpty()) {
            extensions = new ArrayList<HelloExtension>();
        }
        extensions.add(ext);
        encodedLength = -1;
    }

    HelloExtension get(ExtensionType type) {
        for (HelloExtension ext : extensions) {
            if (ext.type == type) {
                return ext;
            }
        }
        return null;
    }

    int length() {
        if (encodedLength >= 0) {
            return encodedLength;
        }
        if (extensions.isEmpty()) {
            encodedLength = 0;
        } else {
            encodedLength = 2;
            for (HelloExtension ext : extensions) {
                encodedLength += ext.length();
            }
        }
        return encodedLength;
    }

    void send(HandshakeOutStream s) throws IOException {
        int length = length();
        if (length == 0) {
            return;
        }
        s.putInt16(length - 2);
        for (HelloExtension ext : extensions) {
            ext.send(s);
        }
    }

    void print(PrintStream s) throws IOException {
        for (HelloExtension ext : extensions) {
            s.println(ext.toString());
        }
    }
}

final class ExtensionType {

    final int id;
    final String name;

    private ExtensionType(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public String toString() {
        return name;
    }

    static List<ExtensionType> knownExtensions =
                                            new ArrayList<ExtensionType>(14);

    static ExtensionType get(int id) {
        for (ExtensionType ext : knownExtensions) {
            if (ext.id == id) {
                return ext;
            }
        }
        return new ExtensionType(id, "type_" + id);
    }

    private static ExtensionType e(int id, String name) {
        ExtensionType ext = new ExtensionType(id, name);
        knownExtensions.add(ext);
        return ext;
    }

    // extensions defined in RFC 3546
    final static ExtensionType EXT_SERVER_NAME =
            e(0x0000, "server_name");            // IANA registry value: 0
    final static ExtensionType EXT_MAX_FRAGMENT_LENGTH =
            e(0x0001, "max_fragment_length");    // IANA registry value: 1
    final static ExtensionType EXT_CLIENT_CERTIFICATE_URL =
            e(0x0002, "client_certificate_url"); // IANA registry value: 2
    final static ExtensionType EXT_TRUSTED_CA_KEYS =
            e(0x0003, "trusted_ca_keys");        // IANA registry value: 3
    final static ExtensionType EXT_TRUNCATED_HMAC =
            e(0x0004, "truncated_hmac");         // IANA registry value: 4
    final static ExtensionType EXT_STATUS_REQUEST =
            e(0x0005, "status_request");         // IANA registry value: 5

    // extensions defined in RFC 4681
    final static ExtensionType EXT_USER_MAPPING =
            e(0x0006, "user_mapping");           // IANA registry value: 6

    // extensions defined in RFC 5081
    final static ExtensionType EXT_CERT_TYPE =
            e(0x0009, "cert_type");              // IANA registry value: 9

    // extensions defined in RFC 4492 (ECC)
    final static ExtensionType EXT_ELLIPTIC_CURVES =
            e(0x000A, "elliptic_curves");        // IANA registry value: 10
    final static ExtensionType EXT_EC_POINT_FORMATS =
            e(0x000B, "ec_point_formats");       // IANA registry value: 11

    // extensions defined in RFC 5054
    final static ExtensionType EXT_SRP =
            e(0x000C, "srp");                    // IANA registry value: 12

    // extensions defined in RFC 5246
    final static ExtensionType EXT_SIGNATURE_ALGORITHMS =
            e(0x000D, "signature_algorithms");   // IANA registry value: 13

    // extensions defined in RFC 7627
    static final ExtensionType EXT_EXTENDED_MASTER_SECRET =
            e(0x0017, "extended_master_secret"); // IANA registry value: 23

    // extensions defined in RFC 5746
    final static ExtensionType EXT_RENEGOTIATION_INFO =
            e(0xff01, "renegotiation_info");     // IANA registry value: 65281
}

abstract class HelloExtension {

    final ExtensionType type;

    HelloExtension(ExtensionType type) {
        this.type = type;
    }

    // Length of the encoded extension, including the type and length fields
    abstract int length();

    abstract void send(HandshakeOutStream s) throws IOException;

    public abstract String toString();

}

final class UnknownExtension extends HelloExtension {

    private final byte[] data;

    UnknownExtension(HandshakeInStream s, int len, ExtensionType type)
            throws IOException {
        super(type);
        data = new byte[len];
        // s.read() does not handle 0-length arrays.
        if (len != 0) {
            s.read(data);
        }
    }

    int length() {
        return 4 + data.length;
    }

    void send(HandshakeOutStream s) throws IOException {
        s.putInt16(type.id);
        s.putBytes16(data);
    }

    public String toString() {
        return "Unsupported extension " + type + ", data: " + Debug.toString(data);
    }
}

/*
 * Support for the server_name extension is incomplete. Parsing is implemented
 * so that we get nicer debug output, but we neither send it nor do we do
 * act on it if we receive it.
 */
final class ServerNameExtension extends HelloExtension {

    final static int NAME_HOST_NAME = 0;

    private List<ServerName> names;

    ServerNameExtension(HandshakeInStream s, int len)
            throws IOException {
        super(ExtensionType.EXT_SERVER_NAME);
        names = new ArrayList<ServerName>();
        while (len > 0) {
            ServerName name = new ServerName(s);
            names.add(name);
            len -= name.length + 2;
        }
        if (len != 0) {
            throw new SSLProtocolException("Invalid server_name extension");
        }
    }

    static class ServerName {
        final int length;
        final int type;
        final byte[] data;
        final String hostname;

        ServerName(HandshakeInStream s) throws IOException {
            length = s.getInt16();      // ServerNameList length
            type = s.getInt8();         // NameType
            data = s.getBytes16();      // HostName (length read in getBytes16)
            if (type == NAME_HOST_NAME) {
                hostname = new String(data, "UTF8");
            } else {
                hostname = null;
            }
        }

        public String toString() {
            if (type == NAME_HOST_NAME) {
                return "host_name: " + hostname;
            } else {
                return "unknown-" + type + ": " + Debug.toString(data);
            }
        }
    }

    int length() {
        throw new RuntimeException("not yet supported");
    }

    void send(HandshakeOutStream s) throws IOException {
        throw new RuntimeException("not yet supported");
    }

    public String toString() {
        return "Unsupported extension " + type + ", " + names.toString();
    }
}

final class SupportedEllipticCurvesExtension extends HelloExtension {

    /* Class and subclass dynamic debugging support */
    private static final Debug debug = Debug.getInstance("ssl");

    private static final int ARBITRARY_PRIME = 0xff01;
    private static final int ARBITRARY_CHAR2 = 0xff02;

    // speed up the searching
    private static final Map<String, Integer> oidToIdMap = new HashMap<String, Integer>();
    private static final Map<Integer, String> idToOidMap = new HashMap<Integer, String>();

    // speed up the parameters construction
    private static final Map<Integer, AlgorithmParameters> idToParams =
        new HashMap<Integer, AlgorithmParameters>();

    // the supported elliptic curves
    private static final int[] supportedCurveIds;

    // the curves of the extension
    private final int[] curveIds;

    // See sun.security.util.CurveDB for the OIDs
    private static enum NamedEllipticCurve {
        T163_K1(1,  "sect163k1",    "1.3.132.0.1",      true),  // NIST K-163
        T163_R1(2,  "sect163r1",    "1.3.132.0.2",      false),
        T163_R2(3,  "sect163r2",    "1.3.132.0.15",     true),  // NIST B-163
        T193_R1(4,  "sect193r1",    "1.3.132.0.24",     false),
        T193_R2(5,  "sect193r2",    "1.3.132.0.25",     false),
        T233_K1(6,  "sect233k1",    "1.3.132.0.26",     true),  // NIST K-233
        T233_R1(7,  "sect233r1",    "1.3.132.0.27",     true),  // NIST B-233
        T239_K1(8,  "sect239k1",    "1.3.132.0.3",      false),
        T283_K1(9,  "sect283k1",    "1.3.132.0.16",     true),  // NIST K-283
        T283_R1(10, "sect283r1",    "1.3.132.0.17",     true),  // NIST B-283
        T409_K1(11, "sect409k1",    "1.3.132.0.36",     true),  // NIST K-409
        T409_R1(12, "sect409r1",    "1.3.132.0.37",     true),  // NIST B-409
        T571_K1(13, "sect571k1",    "1.3.132.0.38",     true),  // NIST K-571
        T571_R1(14, "sect571r1",    "1.3.132.0.39",     true),  // NIST B-571

        P160_K1(15, "secp160k1",    "1.3.132.0.9",      false),
        P160_R1(16, "secp160r1",    "1.3.132.0.8",      false),
        P160_R2(17, "secp160r2",    "1.3.132.0.30",     false),
        P192_K1(18, "secp192k1",    "1.3.132.0.31",     false),
        P192_R1(19, "secp192r1",    "1.2.840.10045.3.1.1", true), // NIST P-192
        P224_K1(20, "secp224k1",    "1.3.132.0.32",     false),
        P224_R1(21, "secp224r1",    "1.3.132.0.33",     true),  // NIST P-224
        P256_K1(22, "secp256k1",    "1.3.132.0.10",     false),
        P256_R1(23, "secp256r1",    "1.2.840.10045.3.1.7", true), // NIST P-256
        P384_R1(24, "secp384r1",    "1.3.132.0.34",     true),  // NIST P-384
        P521_R1(25, "secp521r1",    "1.3.132.0.35",     true);  // NIST P-521

        int          id;
        String       name;
        String       oid;
        boolean      isFips;

        NamedEllipticCurve(int id, String name, String oid, boolean isFips) {
            this.id = id;
            this.name = name;
            this.oid = oid;
            this.isFips = isFips;

            if (oidToIdMap.put(oid, id) != null ||
                idToOidMap.put(id, oid) != null) {

                throw new RuntimeException(
                        "Duplicate named elliptic curve definition: " + name);
            }
        }

        static NamedEllipticCurve getCurve(String name, boolean requireFips) {
            for (NamedEllipticCurve curve : NamedEllipticCurve.values()) {
                if (curve.name.equals(name) && (!requireFips || curve.isFips)) {
                    return curve;
                }
            }

            return null;
        }
    }

    static {
        boolean requireFips = SunJSSE.isFIPS();

        // hack code to initialize NamedEllipticCurve
        NamedEllipticCurve nec =
                NamedEllipticCurve.getCurve("secp256r1", false);

        // The value of the System Property defines a list of enabled named
        // curves in preference order, separated with comma.  For example:
        //
        //      jdk.tls.namedGroups="secp521r1, secp256r1, secp384r1"
        //
        // If the System Property is not defined or the value is empty, the
        // default curves and preferences will be used.
        String property = AccessController.doPrivileged(
                new GetPropertyAction("jdk.tls.namedGroups"));
        if (property != null && property.length() != 0) {
            // remove double quote marks from beginning/end of the property
            if (property.length() > 1 && property.charAt(0) == '"' &&
                    property.charAt(property.length() - 1) == '"') {
                property = property.substring(1, property.length() - 1);
            }
        }

        ArrayList<Integer> idList;
        if (property != null && property.length() != 0) {   // customized curves
            String[] curves = property.split(",");
            idList = new ArrayList<Integer>(curves.length);
            for (String curve : curves) {
                curve = curve.trim();
                if (!curve.isEmpty()) {
                    NamedEllipticCurve namedCurve =
                            NamedEllipticCurve.getCurve(curve, requireFips);
                    if (namedCurve != null) {
                        if (isAvailableCurve(namedCurve.id)) {
                            idList.add(namedCurve.id);
                        }
                    }   // ignore unknown curves
                }
            }
            if (idList.isEmpty() && JsseJce.isEcAvailable()) {
                throw new IllegalArgumentException(
                        "System property jdk.tls.namedGroups(" + property + ") " +
                                "contains no supported elliptic curves");
            }
        } else {        // default curves
            int[] ids;
            if (requireFips) {
                ids = new int[] {
                    // only NIST curves in FIPS mode
                    23, 24, 25, 9, 10, 11, 12, 13, 14,
                };
            } else {
                ids = new int[] {
                    // NIST curves first
                    23, 24, 25, 9, 10, 11, 12, 13, 14,
                    // non-NIST curves
                    22,
                };
            }

            idList = new ArrayList<Integer>(ids.length);
            for (int curveId : ids) {
                if (isAvailableCurve(curveId)) {
                    idList.add(curveId);
                }
            }
        }

        if (debug != null && idList.isEmpty()) {
            debug.println(
                    "Initialized [jdk.tls.namedGroups|default] list contains " +
                            "no available elliptic curves. " +
                            (property != null ? "(" + property + ")" : "[Default]"));
        }

        supportedCurveIds = new int[idList.size()];
        int i = 0;
        for (Integer id : idList) {
            supportedCurveIds[i++] = id;
        }
    }

    // check whether the curve is supported by the underlying providers
    private static boolean isAvailableCurve(int curveId) {
        String oid = idToOidMap.get(curveId);
        if (oid != null) {
            AlgorithmParameters params = null;
            try {
                params = JsseJce.getAlgorithmParameters("EC");
                params.init(new ECGenParameterSpec(oid));
            } catch (Exception e) {
                return false;
            }

            // cache the parameters
            idToParams.put(curveId, params);

            return true;
        }

        return false;
    }

    private SupportedEllipticCurvesExtension(int[] curveIds) {
        super(ExtensionType.EXT_ELLIPTIC_CURVES);
        this.curveIds = curveIds;
    }

    SupportedEllipticCurvesExtension(HandshakeInStream s, int len)
            throws IOException {
        super(ExtensionType.EXT_ELLIPTIC_CURVES);
        int k = s.getInt16();
        if (((len & 1) != 0) || (k + 2 != len)) {
            throw new SSLProtocolException("Invalid " + type + " extension");
        }

        // Note: unknown curves will be ignored later.
        curveIds = new int[k >> 1];
        for (int i = 0; i < curveIds.length; i++) {
            curveIds[i] = s.getInt16();
        }
    }

    // get the preferred active curve
    static int getActiveCurves(AlgorithmConstraints constraints) {
        return getPreferredCurve(supportedCurveIds, constraints);
    }

    static boolean hasActiveCurves(AlgorithmConstraints constraints) {
               return getActiveCurves(constraints) >= 0;
    }

    static SupportedEllipticCurvesExtension createExtension(
            AlgorithmConstraints constraints) {

        ArrayList<Integer> idList = new ArrayList<Integer>(supportedCurveIds.length);
        for (int curveId : supportedCurveIds) {
            if (constraints.permits(
                    EnumSet.of(CryptoPrimitive.KEY_AGREEMENT),
                    "EC", idToParams.get(curveId))) {
                idList.add(curveId);
            }
        }

        if (!idList.isEmpty()) {
            int[] ids = new int[idList.size()];
            int i = 0;
            for (Integer id : idList) {
                ids[i++] = id;
            }

            return new SupportedEllipticCurvesExtension(ids);
        }

        return null;
    }

    // get the preferred activated curve
    int getPreferredCurve(AlgorithmConstraints constraints) {
        return getPreferredCurve(curveIds, constraints);
    }

    // get a preferred activated curve
    private static int getPreferredCurve(int[] curves,
                                         AlgorithmConstraints constraints) {
        for (int curveId : curves) {
            if (isSupported(curveId) && constraints.permits(
                    EnumSet.of(CryptoPrimitive.KEY_AGREEMENT),
                                "EC", idToParams.get(curveId))) {
                return curveId;
            }
        }

        return -1;
    }

    boolean contains(int index) {
        for (int curveId : curveIds) {
            if (index == curveId) {
                return true;
            }
        }
        return false;
    }

    int length() {
        return 6 + (curveIds.length << 1);
    }

    void send(HandshakeOutStream s) throws IOException {
        s.putInt16(type.id);
        int k = curveIds.length << 1;
        s.putInt16(k + 2);
        s.putInt16(k);
        for (int curveId : curveIds) {
            s.putInt16(curveId);
        }
    }

    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("Extension " + type + ", curve names: {");
        boolean first = true;
        for (int curveId : curveIds) {
            if (first) {
                first = false;
            } else {
                sb.append(", ");
            }
            String curveName = getCurveName(curveId);
            if (curveName != null) {
                sb.append(curveName);
            } else if (curveId == ARBITRARY_PRIME) {
                sb.append("arbitrary_explicit_prime_curves");
            } else if (curveId == ARBITRARY_CHAR2) {
                sb.append("arbitrary_explicit_char2_curves");
            } else {
                sb.append("unknown curve " + curveId);
            }
        }
        sb.append("}");
        return sb.toString();
    }

    // Test whether the given curve is supported.
    static boolean isSupported(int index) {
        for (int curveId : supportedCurveIds) {
            if (index == curveId) {
                return true;
            }
        }

        return false;
    }

    static int getCurveIndex(ECParameterSpec params) {
        String oid = JsseJce.getNamedCurveOid(params);
        if (oid == null) {
            return -1;
        }
        Integer n = oidToIdMap.get(oid);
        return (n == null) ? -1 : n;
    }

    static String getCurveOid(int index) {
        return idToOidMap.get(index);
    }

    static ECGenParameterSpec getECGenParamSpec(int index) {
        AlgorithmParameters params = idToParams.get(index);
        try {
            return params.getParameterSpec(ECGenParameterSpec.class);
        } catch (InvalidParameterSpecException ipse) {
            // should be unlikely
            String curveOid = getCurveOid(index);
            return new ECGenParameterSpec(curveOid);
        }
    }

    private static String getCurveName(int index) {
        for (NamedEllipticCurve namedCurve : NamedEllipticCurve.values()) {
            if (namedCurve.id == index) {
                return namedCurve.name;
            }
        }

        return null;
    }
}

final class SupportedEllipticPointFormatsExtension extends HelloExtension {

    final static int FMT_UNCOMPRESSED = 0;
    final static int FMT_ANSIX962_COMPRESSED_PRIME = 1;
    final static int FMT_ANSIX962_COMPRESSED_CHAR2 = 2;

    static final HelloExtension DEFAULT =
        new SupportedEllipticPointFormatsExtension(new byte[] {FMT_UNCOMPRESSED});

    private final byte[] formats;

    private SupportedEllipticPointFormatsExtension(byte[] formats) {
        super(ExtensionType.EXT_EC_POINT_FORMATS);
        this.formats = formats;
    }

    SupportedEllipticPointFormatsExtension(HandshakeInStream s, int len)
            throws IOException {
        super(ExtensionType.EXT_EC_POINT_FORMATS);
        formats = s.getBytes8();
        // RFC 4492 says uncompressed points must always be supported.
        // Check just to make sure.
        boolean uncompressed = false;
        for (int format : formats) {
            if (format == FMT_UNCOMPRESSED) {
                uncompressed = true;
                break;
            }
        }
        if (uncompressed == false) {
            throw new SSLProtocolException
                ("Peer does not support uncompressed points");
        }
    }

    int length() {
        return 5 + formats.length;
    }

    void send(HandshakeOutStream s) throws IOException {
        s.putInt16(type.id);
        s.putInt16(formats.length + 1);
        s.putBytes8(formats);
    }

    private static String toString(byte format) {
        int f = format & 0xff;
        switch (f) {
        case FMT_UNCOMPRESSED:
            return "uncompressed";
        case FMT_ANSIX962_COMPRESSED_PRIME:
            return "ansiX962_compressed_prime";
        case FMT_ANSIX962_COMPRESSED_CHAR2:
            return "ansiX962_compressed_char2";
        default:
            return "unknown-" + f;
        }
    }

    public String toString() {
        List<String> list = new ArrayList<String>();
        for (byte format : formats) {
            list.add(toString(format));
        }
        return "Extension " + type + ", formats: " + list;
    }
}

/*
 * For secure renegotiation, RFC5746 defines a new TLS extension,
 * "renegotiation_info" (with extension type 0xff01), which contains a
 * cryptographic binding to the enclosing TLS connection (if any) for
 * which the renegotiation is being performed.  The "extension data"
 * field of this extension contains a "RenegotiationInfo" structure:
 *
 *      struct {
 *          opaque renegotiated_connection<0..255>;
 *      } RenegotiationInfo;
 */
final class RenegotiationInfoExtension extends HelloExtension {
    private final byte[] renegotiated_connection;

    RenegotiationInfoExtension(byte[] clientVerifyData,
                byte[] serverVerifyData) {
        super(ExtensionType.EXT_RENEGOTIATION_INFO);

        if (clientVerifyData.length != 0) {
            renegotiated_connection =
                    new byte[clientVerifyData.length + serverVerifyData.length];
            System.arraycopy(clientVerifyData, 0, renegotiated_connection,
                    0, clientVerifyData.length);

            if (serverVerifyData.length != 0) {
                System.arraycopy(serverVerifyData, 0, renegotiated_connection,
                        clientVerifyData.length, serverVerifyData.length);
            }
        } else {
            // ignore both the client and server verify data.
            renegotiated_connection = new byte[0];
        }
    }

    RenegotiationInfoExtension(HandshakeInStream s, int len)
                throws IOException {
        super(ExtensionType.EXT_RENEGOTIATION_INFO);

        // check the extension length
        if (len < 1) {
            throw new SSLProtocolException("Invalid " + type + " extension");
        }

        int renegoInfoDataLen = s.getInt8();
        if (renegoInfoDataLen + 1 != len) {  // + 1 = the byte we just read
            throw new SSLProtocolException("Invalid " + type + " extension");
        }

        renegotiated_connection = new byte[renegoInfoDataLen];
        if (renegoInfoDataLen != 0) {
            s.read(renegotiated_connection, 0, renegoInfoDataLen);
        }
    }


    // Length of the encoded extension, including the type and length fields
    int length() {
        return 5 + renegotiated_connection.length;
    }

    void send(HandshakeOutStream s) throws IOException {
        s.putInt16(type.id);
        s.putInt16(renegotiated_connection.length + 1);
        s.putBytes8(renegotiated_connection);
    }

    boolean isEmpty() {
        return renegotiated_connection.length == 0;
    }

    byte[] getRenegotiatedConnection() {
        return renegotiated_connection;
    }

    public String toString() {
        return "Extension " + type + ", renegotiated_connection: " +
                    (renegotiated_connection.length == 0 ? "<empty>" :
                    Debug.toString(renegotiated_connection));
    }

}