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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * particular file as subject to the "Classpath" exception as provided
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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package sun.security.ssl;

import java.io.*;
import java.util.*;
import java.security.*;
import java.nio.ByteBuffer;
import java.util.function.BiFunction;

import javax.crypto.*;
import javax.crypto.spec.*;

import javax.net.ssl.*;
import sun.security.util.HexDumpEncoder;

import sun.security.internal.spec.*;
import sun.security.internal.interfaces.TlsMasterSecret;

import sun.security.ssl.HandshakeMessage.*;
import sun.security.ssl.CipherSuite.*;

import static sun.security.ssl.CipherSuite.PRF.*;
import static sun.security.ssl.CipherSuite.CipherType.*;
import static sun.security.ssl.NamedGroupType.*;

Handshaker ... processes handshake records from an SSL V3.0
data stream, handling all the details of the handshake protocol.
Note that the real protocol work is done in two subclasses, the  base
class just provides the control flow and key generation framework.
Author:
David Brownell/**
 * Handshaker ... processes handshake records from an SSL V3.0
 * data stream, handling all the details of the handshake protocol.
 *
 * Note that the real protocol work is done in two subclasses, the  base
 * class just provides the control flow and key generation framework.
 *
 * @author David Brownell
 */
abstract class Handshaker {

    // protocol version being established using this Handshaker
    ProtocolVersion protocolVersion;

    // the currently active protocol version during a renegotiation
    ProtocolVersion     activeProtocolVersion;

    // security parameters for secure renegotiation.
    boolean             secureRenegotiation;
    byte[]              clientVerifyData;
    byte[]              serverVerifyData;

    // Is it an initial negotiation  or a renegotiation?
    boolean                     isInitialHandshake;

    // List of enabled protocols
    private ProtocolList        enabledProtocols;

    // List of enabled CipherSuites
    private CipherSuiteList     enabledCipherSuites;

    // The endpoint identification protocol
    String                      identificationProtocol;

    // The cryptographic algorithm constraints
    AlgorithmConstraints        algorithmConstraints = null;

    // Local supported signature and algorithms
    private Collection<SignatureAndHashAlgorithm> localSupportedSignAlgs;

    // Peer supported signature and algorithms
    Collection<SignatureAndHashAlgorithm> peerSupportedSignAlgs;

    /*
     * List of active protocols
     *
     * Active protocols is a subset of enabled protocols, and will
     * contain only those protocols that have vaild cipher suites
     * enabled.
     */
    private ProtocolList       activeProtocols;

    /*
     * List of active cipher suites
     *
     * Active cipher suites is a subset of enabled cipher suites, and will
     * contain only those cipher suites available for the active protocols.
     */
    private CipherSuiteList     activeCipherSuites;

    // The server name indication and matchers
    List<SNIServerName> serverNames = Collections.<SNIServerName>emptyList();
    Collection<SNIMatcher> sniMatchers = Collections.<SNIMatcher>emptyList();

    // List of local ApplicationProtocols
    String[] localApl = null;

    // Negotiated ALPN value
    String applicationProtocol = null;

    // Application protocol callback function (for SSLEngine)
    BiFunction<SSLEngine,List<String>,String>
        appProtocolSelectorSSLEngine = null;

    // Application protocol callback function (for SSLSocket)
    BiFunction<SSLSocket,List<String>,String>
        appProtocolSelectorSSLSocket = null;

    // The maximum expected network packet size for SSL/TLS/DTLS records.
    int                         maximumPacketSize = 0;

    private boolean             isClient;
    private boolean             needCertVerify;

    SSLSocketImpl               conn = null;
    SSLEngineImpl               engine = null;

    HandshakeHash               handshakeHash;
    HandshakeInStream           input;
    HandshakeOutStream          output;
    SSLContextImpl              sslContext;
    RandomCookie                clnt_random, svr_random;
    SSLSessionImpl              session;

    HandshakeStateManager       handshakeState;
    boolean                     clientHelloDelivered;
    boolean                     serverHelloRequested;
    boolean                     handshakeActivated;
    boolean                     handshakeFinished;

    // current CipherSuite. Never null, initially SSL_NULL_WITH_NULL_NULL
    CipherSuite         cipherSuite;

    // current key exchange. Never null, initially K_NULL
    KeyExchange         keyExchange;

    // True if this session is being resumed (fast handshake)
    boolean             resumingSession;

    // True if it's OK to start a new SSL session
    boolean             enableNewSession;

    // Whether local cipher suites preference should be honored during
    // handshaking?
    //
    // Note that in this provider, this option only applies to server side.
    // Local cipher suites preference is always honored in client side in
    // this provider.
    boolean preferLocalCipherSuites = false;

    // Temporary storage for the individual keys. Set by
    // calculateConnectionKeys() and cleared once the ciphers are
    // activated.
    private SecretKey clntWriteKey, svrWriteKey;
    private IvParameterSpec clntWriteIV, svrWriteIV;
    private SecretKey clntMacSecret, svrMacSecret;

    /*
     * Delegated task subsystem data structures.
     *
     * If thrown is set, we need to propagate this back immediately
     * on entry into processMessage().
     *
     * Data is protected by the SSLEngine.this lock.
     */
    private volatile boolean taskDelegated = false;
    private volatile DelegatedTask<?> delegatedTask = null;
    private volatile Exception thrown = null;

    // Could probably use a java.util.concurrent.atomic.AtomicReference
    // here instead of using this lock.  Consider changing.
    private Object thrownLock = new Object();

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

    // By default, disable the unsafe legacy session renegotiation
    static final boolean allowUnsafeRenegotiation = Debug.getBooleanProperty(
                    "sun.security.ssl.allowUnsafeRenegotiation", false);

    // For maximum interoperability and backward compatibility, RFC 5746
    // allows server (or client) to accept ClientHello (or ServerHello)
    // message without the secure renegotiation_info extension or SCSV.
    //
    // For maximum security, RFC 5746 also allows server (or client) to
    // reject such message with a fatal "handshake_failure" alert.
    //
    // By default, allow such legacy hello messages.
    static final boolean allowLegacyHelloMessages = Debug.getBooleanProperty(
                    "sun.security.ssl.allowLegacyHelloMessages", true);

    // To prevent the TLS renegotiation issues, by setting system property
    // "jdk.tls.rejectClientInitiatedRenegotiation" to true, applications in
    // server side can disable all client initiated SSL renegotiations
    // regardless of the support of TLS protocols.
    //
    // By default, allow client initiated renegotiations.
    static final boolean rejectClientInitiatedRenego =
            Debug.getBooleanProperty(
                "jdk.tls.rejectClientInitiatedRenegotiation", false);

    // To switch off the extended_master_secret extension.
    static final boolean useExtendedMasterSecret;

    // Allow session resumption without Extended Master Secret extension.
    static final boolean allowLegacyResumption =
            Debug.getBooleanProperty("jdk.tls.allowLegacyResumption", true);

    // Allow full handshake without Extended Master Secret extension.
    static final boolean allowLegacyMasterSecret =
            Debug.getBooleanProperty("jdk.tls.allowLegacyMasterSecret", true);

    // Is it requested to use extended master secret extension?
    boolean requestedToUseEMS = false;

    // need to dispose the object when it is invalidated
    boolean invalidated;

    /*
     * Is this an instance for Datagram Transport Layer Security (DTLS)?
     */
    final boolean isDTLS;

    // Is the extended_master_secret extension supported?
    static {
        boolean supportExtendedMasterSecret = true;
        try {
            KeyGenerator kg =
                JsseJce.getKeyGenerator("SunTlsExtendedMasterSecret");
        } catch (NoSuchAlgorithmException nae) {
            supportExtendedMasterSecret = false;
        }

        if (supportExtendedMasterSecret) {
            useExtendedMasterSecret = Debug.getBooleanProperty(
                    "jdk.tls.useExtendedMasterSecret", true);
        } else {
            useExtendedMasterSecret = false;
        }
    }

    Handshaker(SSLSocketImpl c, SSLContextImpl context,
            ProtocolList enabledProtocols, boolean needCertVerify,
            boolean isClient, ProtocolVersion activeProtocolVersion,
            boolean isInitialHandshake, boolean secureRenegotiation,
            byte[] clientVerifyData, byte[] serverVerifyData) {
        this.conn = c;
        this.isDTLS = false;
        init(context, enabledProtocols, needCertVerify, isClient,
            activeProtocolVersion, isInitialHandshake, secureRenegotiation,
            clientVerifyData, serverVerifyData);
   }

    Handshaker(SSLEngineImpl engine, SSLContextImpl context,
            ProtocolList enabledProtocols, boolean needCertVerify,
            boolean isClient, ProtocolVersion activeProtocolVersion,
            boolean isInitialHandshake, boolean secureRenegotiation,
            byte[] clientVerifyData, byte[] serverVerifyData,
            boolean isDTLS) {
        this.engine = engine;
        this.isDTLS = isDTLS;
        init(context, enabledProtocols, needCertVerify, isClient,
            activeProtocolVersion, isInitialHandshake, secureRenegotiation,
            clientVerifyData, serverVerifyData);
    }

    private void init(SSLContextImpl context, ProtocolList enabledProtocols,
            boolean needCertVerify, boolean isClient,
            ProtocolVersion activeProtocolVersion,
            boolean isInitialHandshake, boolean secureRenegotiation,
            byte[] clientVerifyData, byte[] serverVerifyData) {

        if (debug != null && Debug.isOn("handshake")) {
            System.out.println(
                "Allow unsafe renegotiation: " + allowUnsafeRenegotiation +
                "\nAllow legacy hello messages: " + allowLegacyHelloMessages +
                "\nIs initial handshake: " + isInitialHandshake +
                "\nIs secure renegotiation: " + secureRenegotiation);
        }

        this.sslContext = context;
        this.isClient = isClient;
        this.needCertVerify = needCertVerify;
        this.activeProtocolVersion = activeProtocolVersion;
        this.isInitialHandshake = isInitialHandshake;
        this.secureRenegotiation = secureRenegotiation;
        this.clientVerifyData = clientVerifyData;
        this.serverVerifyData = serverVerifyData;
        this.enableNewSession = true;
        this.invalidated = false;
        this.handshakeState = new HandshakeStateManager(isDTLS);
        this.clientHelloDelivered = false;
        this.serverHelloRequested = false;
        this.handshakeActivated = false;
        this.handshakeFinished = false;

        setCipherSuite(CipherSuite.C_NULL);
        setEnabledProtocols(enabledProtocols);

        if (conn != null) {
            algorithmConstraints = new SSLAlgorithmConstraints(conn, true);
        } else {        // engine != null
            algorithmConstraints = new SSLAlgorithmConstraints(engine, true);
        }
    }

    /*
     * Reroutes calls to the SSLSocket or SSLEngine (*SE).
     *
     * We could have also done it by extra classes
     * and letting them override, but this seemed much
     * less involved.
     */
    void fatalSE(byte b, String diagnostic) throws IOException {
        fatalSE(b, diagnostic, null);
    }

    void fatalSE(byte b, Throwable cause) throws IOException {
        fatalSE(b, null, cause);
    }

    void fatalSE(byte b, String diagnostic, Throwable cause)
            throws IOException {
        if (conn != null) {
            conn.fatal(b, diagnostic, cause);
        } else {
            engine.fatal(b, diagnostic, cause);
        }
    }

    void warningSE(byte b) {
        if (conn != null) {
            conn.warning(b);
        } else {
            engine.warning(b);
        }
    }

    // ONLY used by ClientHandshaker to setup the peer host in SSLSession.
    String getHostSE() {
        if (conn != null) {
            return conn.getHost();
        } else {
            return engine.getPeerHost();
        }
    }

    // ONLY used by ServerHandshaker to setup the peer host in SSLSession.
    String getHostAddressSE() {
        if (conn != null) {
            return conn.getInetAddress().getHostAddress();
        } else {
            /*
             * This is for caching only, doesn't matter that's is really
             * a hostname.  The main thing is that it doesn't do
             * a reverse DNS lookup, potentially slowing things down.
             */
            return engine.getPeerHost();
        }
    }

    int getPortSE() {
        if (conn != null) {
            return conn.getPort();
        } else {
            return engine.getPeerPort();
        }
    }

    int getLocalPortSE() {
        if (conn != null) {
            return conn.getLocalPort();
        } else {
            return -1;
        }
    }

    AccessControlContext getAccSE() {
        if (conn != null) {
            return conn.getAcc();
        } else {
            return engine.getAcc();
        }
    }

    String getEndpointIdentificationAlgorithmSE() {
        SSLParameters paras;
        if (conn != null) {
            paras = conn.getSSLParameters();
        } else {
            paras = engine.getSSLParameters();
        }

        return paras.getEndpointIdentificationAlgorithm();
    }

    private void setVersionSE(ProtocolVersion protocolVersion) {
        if (conn != null) {
            conn.setVersion(protocolVersion);
        } else {
            engine.setVersion(protocolVersion);
        }
    }

    
Set the active protocol version and propagate it to the SSLSocket
and our handshake streams. Called from ClientHandshaker
and ServerHandshaker with the negotiated protocol version.
/**
     * Set the active protocol version and propagate it to the SSLSocket
     * and our handshake streams. Called from ClientHandshaker
     * and ServerHandshaker with the negotiated protocol version.
     */
    void setVersion(ProtocolVersion protocolVersion) {
        this.protocolVersion = protocolVersion;
        setVersionSE(protocolVersion);
    }

    
Set the enabled protocols. Called from the constructor or
SSLSocketImpl/SSLEngineImpl.setEnabledProtocols() (if the
handshake is not yet in progress).
/**
     * Set the enabled protocols. Called from the constructor or
     * SSLSocketImpl/SSLEngineImpl.setEnabledProtocols() (if the
     * handshake is not yet in progress).
     */
    void setEnabledProtocols(ProtocolList enabledProtocols) {
        activeCipherSuites = null;
        activeProtocols = null;

        this.enabledProtocols = enabledProtocols;
    }

    
Set the enabled cipher suites. Called from
SSLSocketImpl/SSLEngineImpl.setEnabledCipherSuites() (if the
handshake is not yet in progress).
/**
     * Set the enabled cipher suites. Called from
     * SSLSocketImpl/SSLEngineImpl.setEnabledCipherSuites() (if the
     * handshake is not yet in progress).
     */
    void setEnabledCipherSuites(CipherSuiteList enabledCipherSuites) {
        activeCipherSuites = null;
        activeProtocols = null;
        this.enabledCipherSuites = enabledCipherSuites;
    }

    
Set the algorithm constraints. Called from the constructor or
SSLSocketImpl/SSLEngineImpl.setAlgorithmConstraints() (if the
handshake is not yet in progress).
/**
     * Set the algorithm constraints. Called from the constructor or
     * SSLSocketImpl/SSLEngineImpl.setAlgorithmConstraints() (if the
     * handshake is not yet in progress).
     */
    void setAlgorithmConstraints(AlgorithmConstraints algorithmConstraints) {
        activeCipherSuites = null;
        activeProtocols = null;

        this.algorithmConstraints =
            new SSLAlgorithmConstraints(algorithmConstraints);
        this.localSupportedSignAlgs = null;
    }

    Collection<SignatureAndHashAlgorithm> getLocalSupportedSignAlgs() {
        if (localSupportedSignAlgs == null) {
            localSupportedSignAlgs =
                SignatureAndHashAlgorithm.getSupportedAlgorithms(
                                                    algorithmConstraints);
        }

        return localSupportedSignAlgs;
    }

    void setPeerSupportedSignAlgs(
            Collection<SignatureAndHashAlgorithm> algorithms) {
        peerSupportedSignAlgs =
            new ArrayList<SignatureAndHashAlgorithm>(algorithms);
    }

    Collection<SignatureAndHashAlgorithm> getPeerSupportedSignAlgs() {
        return peerSupportedSignAlgs;
    }


    
Set the identification protocol. Called from the constructor or
SSLSocketImpl/SSLEngineImpl.setIdentificationProtocol() (if the
handshake is not yet in progress).
/**
     * Set the identification protocol. Called from the constructor or
     * SSLSocketImpl/SSLEngineImpl.setIdentificationProtocol() (if the
     * handshake is not yet in progress).
     */
    void setIdentificationProtocol(String protocol) {
        this.identificationProtocol = protocol;
    }

    
Sets the server name indication of the handshake.
/**
     * Sets the server name indication of the handshake.
     */
    void setSNIServerNames(List<SNIServerName> serverNames) {
        // The serverNames parameter is unmodifiable.
        this.serverNames = serverNames;
    }

    
Sets the server name matchers of the handshaking.
/**
     * Sets the server name matchers of the handshaking.
     */
    void setSNIMatchers(Collection<SNIMatcher> sniMatchers) {
        // The sniMatchers parameter is unmodifiable.
        this.sniMatchers = sniMatchers;
    }

    
Sets the maximum packet size of the handshaking.
/**
     * Sets the maximum packet size of the handshaking.
     */
    void setMaximumPacketSize(int maximumPacketSize) {
        this.maximumPacketSize = maximumPacketSize;
    }

    
Sets the Application Protocol list.
/**
     * Sets the Application Protocol list.
     */
    void setApplicationProtocols(String[] apl) {
        this.localApl = apl;
    }

    
Gets the "negotiated" ALPN value.
/**
     * Gets the "negotiated" ALPN value.
     */
    String getHandshakeApplicationProtocol() {
        return applicationProtocol;
    }

    
Sets the Application Protocol selector function for SSLEngine.
/**
     * Sets the Application Protocol selector function for SSLEngine.
     */
    void setApplicationProtocolSelectorSSLEngine(
        BiFunction<SSLEngine,List<String>,String> selector) {
        this.appProtocolSelectorSSLEngine = selector;
    }

    
Sets the Application Protocol selector function for SSLSocket.
/**
     * Sets the Application Protocol selector function for SSLSocket.
     */
    void setApplicationProtocolSelectorSSLSocket(
        BiFunction<SSLSocket,List<String>,String> selector) {
        this.appProtocolSelectorSSLSocket = selector;
    }

    
Sets the cipher suites preference.
/**
     * Sets the cipher suites preference.
     */
    void setUseCipherSuitesOrder(boolean on) {
        this.preferLocalCipherSuites = on;
    }

    
Prior to handshaking, activate the handshake and initialize the version,
input stream and output stream.
/**
     * Prior to handshaking, activate the handshake and initialize the version,
     * input stream and output stream.
     */
    void activate(ProtocolVersion helloVersion) throws IOException {
        if (activeProtocols == null) {
            activeProtocols = getActiveProtocols();
        }

        if (activeProtocols.collection().isEmpty() ||
                activeProtocols.max.v == ProtocolVersion.NONE.v) {
            throw new SSLHandshakeException(
                    "No appropriate protocol (protocol is disabled or " +
                    "cipher suites are inappropriate)");
        }

        if (activeCipherSuites == null) {
            activeCipherSuites = getActiveCipherSuites();
        }

        if (activeCipherSuites.collection().isEmpty()) {
            throw new SSLHandshakeException("No appropriate cipher suite");
        }

        // temporary protocol version until the actual protocol version
        // is negotiated in the Hello exchange. This affects the record
        // version we sent with the ClientHello.
        if (!isInitialHandshake) {
            protocolVersion = activeProtocolVersion;
        } else {
            protocolVersion = activeProtocols.max;
        }

        if (helloVersion == null || helloVersion.v == ProtocolVersion.NONE.v) {
            helloVersion = activeProtocols.helloVersion;
        }

        // We accumulate digests of the handshake messages so that
        // we can read/write CertificateVerify and Finished messages,
        // getting assurance against some particular active attacks.
        handshakeHash = new HandshakeHash(needCertVerify);

        // Generate handshake input/output stream.
        if (conn != null) {
            input = new HandshakeInStream();
            output = new HandshakeOutStream(conn.outputRecord);

            conn.inputRecord.setHandshakeHash(handshakeHash);
            conn.inputRecord.setHelloVersion(helloVersion);

            conn.outputRecord.setHandshakeHash(handshakeHash);
            conn.outputRecord.setHelloVersion(helloVersion);
            conn.outputRecord.setVersion(protocolVersion);
        } else if (engine != null) {
            input = new HandshakeInStream();
            output = new HandshakeOutStream(engine.outputRecord);

            engine.inputRecord.setHandshakeHash(handshakeHash);
            engine.inputRecord.setHelloVersion(helloVersion);

            engine.outputRecord.setHandshakeHash(handshakeHash);
            engine.outputRecord.setHelloVersion(helloVersion);
            engine.outputRecord.setVersion(protocolVersion);
        }

        handshakeActivated = true;
    }

    
Set cipherSuite and keyExchange to the given CipherSuite.
Does not perform any verification that this is a valid selection,
this must be done before calling this method.
/**
     * Set cipherSuite and keyExchange to the given CipherSuite.
     * Does not perform any verification that this is a valid selection,
     * this must be done before calling this method.
     */
    void setCipherSuite(CipherSuite s) {
        this.cipherSuite = s;
        this.keyExchange = s.keyExchange;
    }

    
Check if the given ciphersuite is enabled and available within the
current active cipher suites.
Does not check if the required server certificates are available.
/**
     * Check if the given ciphersuite is enabled and available within the
     * current active cipher suites.
     *
     * Does not check if the required server certificates are available.
     */
    boolean isNegotiable(CipherSuite s) {
        if (activeCipherSuites == null) {
            activeCipherSuites = getActiveCipherSuites();
        }

        return isNegotiable(activeCipherSuites, s);
    }

    
Check if the given ciphersuite is enabled and available within the
proposed cipher suite list.
Does not check if the required server certificates are available.
/**
     * Check if the given ciphersuite is enabled and available within the
     * proposed cipher suite list.
     *
     * Does not check if the required server certificates are available.
     */
    static final boolean isNegotiable(CipherSuiteList proposed, CipherSuite s) {
        return proposed.contains(s) && s.isNegotiable();
    }

    
Check if the given protocol version is enabled and available.
/**
     * Check if the given protocol version is enabled and available.
     */
    boolean isNegotiable(ProtocolVersion protocolVersion) {
        if (activeProtocols == null) {
            activeProtocols = getActiveProtocols();
        }

        return activeProtocols.contains(protocolVersion);
    }

    
Select a protocol version from the list. Called from
ServerHandshaker to negotiate protocol version.
Return the lower of the protocol version suggested in the
clien hello and the highest supported by the server.
/**
     * Select a protocol version from the list. Called from
     * ServerHandshaker to negotiate protocol version.
     *
     * Return the lower of the protocol version suggested in the
     * clien hello and the highest supported by the server.
     */
    ProtocolVersion selectProtocolVersion(ProtocolVersion protocolVersion) {
        if (activeProtocols == null) {
            activeProtocols = getActiveProtocols();
        }

        return activeProtocols.selectProtocolVersion(protocolVersion);
    }

    
Get the active cipher suites.
In TLS 1.1, many weak or vulnerable cipher suites were obsoleted,
such as TLS_RSA_EXPORT_WITH_RC4_40_MD5. The implementation MUST NOT
negotiate these cipher suites in TLS 1.1 or later mode.
Therefore, when the active protocols only include TLS 1.1 or later,
the client cannot request to negotiate those obsoleted cipher
suites.  That is, the obsoleted suites should not be included in the
client hello. So we need to create a subset of the enabled cipher
suites, the active cipher suites, which does not contain obsoleted
cipher suites of the minimum active protocol.
Return empty list instead of null if no active cipher suites.
/**
     * Get the active cipher suites.
     *
     * In TLS 1.1, many weak or vulnerable cipher suites were obsoleted,
     * such as TLS_RSA_EXPORT_WITH_RC4_40_MD5. The implementation MUST NOT
     * negotiate these cipher suites in TLS 1.1 or later mode.
     *
     * Therefore, when the active protocols only include TLS 1.1 or later,
     * the client cannot request to negotiate those obsoleted cipher
     * suites.  That is, the obsoleted suites should not be included in the
     * client hello. So we need to create a subset of the enabled cipher
     * suites, the active cipher suites, which does not contain obsoleted
     * cipher suites of the minimum active protocol.
     *
     * Return empty list instead of null if no active cipher suites.
     */
    CipherSuiteList getActiveCipherSuites() {
        if (activeCipherSuites == null) {
            if (activeProtocols == null) {
                activeProtocols = getActiveProtocols();
            }

            ArrayList<CipherSuite> suites = new ArrayList<>();
            if (!(activeProtocols.collection().isEmpty()) &&
                    activeProtocols.min.v != ProtocolVersion.NONE.v) {
                Map<NamedGroupType, Boolean> cachedStatus =
                        new EnumMap<>(NamedGroupType.class);
                for (CipherSuite suite : enabledCipherSuites.collection()) {
                    if (suite.isAvailable() &&
                            (!activeProtocols.min.obsoletes(suite)) &&
                            activeProtocols.max.supports(suite)) {
                        if (isActivatable(suite, cachedStatus)) {
                            suites.add(suite);
                        }
                    } else if (debug != null && Debug.isOn("verbose")) {
                        if (activeProtocols.min.obsoletes(suite)) {
                            System.out.println(
                                "Ignoring obsoleted cipher suite: " + suite);
                        } else {
                            System.out.println(
                                "Ignoring unsupported cipher suite: " + suite);
                        }
                    }
                }
            }
            activeCipherSuites = new CipherSuiteList(suites);
        }

        return activeCipherSuites;
    }

    /*
     * Get the active protocol versions.
     *
     * In TLS 1.1, many weak or vulnerable cipher suites were obsoleted,
     * such as TLS_RSA_EXPORT_WITH_RC4_40_MD5. The implementation MUST NOT
     * negotiate these cipher suites in TLS 1.1 or later mode.
     *
     * For example, if "TLS_RSA_EXPORT_WITH_RC4_40_MD5" is the
     * only enabled cipher suite, the client cannot request TLS 1.1 or
     * later, even though TLS 1.1 or later is enabled.  We need to create a
     * subset of the enabled protocols, called the active protocols, which
     * contains protocols appropriate to the list of enabled Ciphersuites.
     *
     * Return empty list instead of null if no active protocol versions.
     */
    ProtocolList getActiveProtocols() {
        if (activeProtocols == null) {
            boolean enabledSSL20Hello = false;
            boolean checkedCurves = false;
            boolean hasCurves = false;
            ArrayList<ProtocolVersion> protocols = new ArrayList<>(4);
            for (ProtocolVersion protocol : enabledProtocols.collection()) {
                // Need not to check the SSL20Hello protocol.
                if (protocol.v == ProtocolVersion.SSL20Hello.v) {
                    enabledSSL20Hello = true;
                    continue;
                }

                if (!algorithmConstraints.permits(
                        EnumSet.of(CryptoPrimitive.KEY_AGREEMENT),
                        protocol.name, null)) {
                    if (debug != null && Debug.isOn("verbose")) {
                        System.out.println(
                            "Ignoring disabled protocol: " + protocol);
                    }

                    continue;
                }

                boolean found = false;
                Map<NamedGroupType, Boolean> cachedStatus =
                        new EnumMap<>(NamedGroupType.class);
                for (CipherSuite suite : enabledCipherSuites.collection()) {
                    if (suite.isAvailable() && (!protocol.obsoletes(suite)) &&
                                               protocol.supports(suite)) {
                        if (isActivatable(suite, cachedStatus)) {
                            protocols.add(protocol);
                            found = true;
                            break;
                        }
                    } else if (debug != null && Debug.isOn("verbose")) {
                        System.out.println(
                            "Ignoring unsupported cipher suite: " + suite +
                                 " for " + protocol);
                    }
                }

                if (!found && (debug != null) && Debug.isOn("handshake")) {
                    System.out.println(
                        "No available cipher suite for " + protocol);
                }
            }

            if (!protocols.isEmpty() && enabledSSL20Hello) {
                protocols.add(ProtocolVersion.SSL20Hello);
            }

            activeProtocols = new ProtocolList(protocols);
        }

        return activeProtocols;
    }

    private boolean isActivatable(CipherSuite suite,
            Map<NamedGroupType, Boolean> cachedStatus) {

        if (algorithmConstraints.permits(
                EnumSet.of(CryptoPrimitive.KEY_AGREEMENT), suite.name, null)) {
            boolean available = true;
            NamedGroupType groupType = suite.keyExchange.groupType;
            if (groupType != NAMED_GROUP_NONE) {
                Boolean checkedStatus = cachedStatus.get(groupType);
                if (checkedStatus == null) {
                    available = SupportedGroupsExtension.isActivatable(
                            algorithmConstraints, groupType);
                    cachedStatus.put(groupType, available);

                    if (!available && debug != null && Debug.isOn("verbose")) {
                        System.out.println("No activated named group");
                    }
                } else {
                    available = checkedStatus.booleanValue();
                }

                if (!available && debug != null && Debug.isOn("verbose")) {
                    System.out.println(
                        "No active named group, ignore " + suite);
                }

                return available;
            } else {
                return true;
            }
        } else if (debug != null && Debug.isOn("verbose")) {
            System.out.println("Ignoring disabled cipher suite: " + suite);
        }

        return false;
    }

    
As long as handshaking has not activated, we can
change whether session creations are allowed.
Callers should do their own checking if handshaking
has activated.
/**
     * As long as handshaking has not activated, we can
     * change whether session creations are allowed.
     *
     * Callers should do their own checking if handshaking
     * has activated.
     */
    void setEnableSessionCreation(boolean newSessions) {
        enableNewSession = newSessions;
    }

    
Create a new read cipher and return it to caller.
/**
     * Create a new read cipher and return it to caller.
     */
    CipherBox newReadCipher() throws NoSuchAlgorithmException {
        BulkCipher cipher = cipherSuite.cipher;
        CipherBox box;
        if (isClient) {
            box = cipher.newCipher(protocolVersion, svrWriteKey, svrWriteIV,
                                   sslContext.getSecureRandom(), false);
            svrWriteKey = null;
            svrWriteIV = null;
        } else {
            box = cipher.newCipher(protocolVersion, clntWriteKey, clntWriteIV,
                                   sslContext.getSecureRandom(), false);
            clntWriteKey = null;
            clntWriteIV = null;
        }
        return box;
    }

    
Create a new write cipher and return it to caller.
/**
     * Create a new write cipher and return it to caller.
     */
    CipherBox newWriteCipher() throws NoSuchAlgorithmException {
        BulkCipher cipher = cipherSuite.cipher;
        CipherBox box;
        if (isClient) {
            box = cipher.newCipher(protocolVersion, clntWriteKey, clntWriteIV,
                                   sslContext.getSecureRandom(), true);
            clntWriteKey = null;
            clntWriteIV = null;
        } else {
            box = cipher.newCipher(protocolVersion, svrWriteKey, svrWriteIV,
                                   sslContext.getSecureRandom(), true);
            svrWriteKey = null;
            svrWriteIV = null;
        }
        return box;
    }

    
Create a new read MAC and return it to caller.
/**
     * Create a new read MAC and return it to caller.
     */
    Authenticator newReadAuthenticator()
            throws NoSuchAlgorithmException, InvalidKeyException {

        Authenticator authenticator = null;
        if (cipherSuite.cipher.cipherType == AEAD_CIPHER) {
            authenticator = new Authenticator(protocolVersion);
        } else {
            MacAlg macAlg = cipherSuite.macAlg;
            if (isClient) {
                authenticator = macAlg.newMac(protocolVersion, svrMacSecret);
                svrMacSecret = null;
            } else {
                authenticator = macAlg.newMac(protocolVersion, clntMacSecret);
                clntMacSecret = null;
            }
        }

        return authenticator;
    }

    
Create a new write MAC and return it to caller.
/**
     * Create a new write MAC and return it to caller.
     */
    Authenticator newWriteAuthenticator()
            throws NoSuchAlgorithmException, InvalidKeyException {

        Authenticator authenticator = null;
        if (cipherSuite.cipher.cipherType == AEAD_CIPHER) {
            authenticator = new Authenticator(protocolVersion);
        } else {
            MacAlg macAlg = cipherSuite.macAlg;
            if (isClient) {
                authenticator = macAlg.newMac(protocolVersion, clntMacSecret);
                clntMacSecret = null;
            } else {
                authenticator = macAlg.newMac(protocolVersion, svrMacSecret);
                svrMacSecret = null;
            }
        }

        return authenticator;
    }

    /*
     * Returns true iff the handshake sequence is done, so that
     * this freshly created session can become the current one.
     */
    boolean isDone() {
        return started() && handshakeState.isEmpty() && handshakeFinished;
    }


    /*
     * Returns the session which was created through this
     * handshake sequence ... should be called after isDone()
     * returns true.
     */
    SSLSessionImpl getSession() {
        return session;
    }

    /*
     * Set the handshake session
     */
    void setHandshakeSessionSE(SSLSessionImpl handshakeSession) {
        if (conn != null) {
            conn.setHandshakeSession(handshakeSession);
        } else {
            engine.setHandshakeSession(handshakeSession);
        }
    }

    void expectingFinishFlightSE() {
        if (conn != null) {
            conn.expectingFinishFlight();
        } else {
            engine.expectingFinishFlight();
        }
    }

    /*
     * Returns true if renegotiation is in use for this connection.
     */
    boolean isSecureRenegotiation() {
        return secureRenegotiation;
    }

    /*
     * Returns the verify_data from the Finished message sent by the client.
     */
    byte[] getClientVerifyData() {
        return clientVerifyData;
    }

    /*
     * Returns the verify_data from the Finished message sent by the server.
     */
    byte[] getServerVerifyData() {
        return serverVerifyData;
    }

    /*
     * This routine is fed SSL handshake records when they become available,
     * and processes messages found therein.
     */
    void processRecord(ByteBuffer record,
            boolean expectingFinished) throws IOException {

        checkThrown();

        /*
         * Store the incoming handshake data, then see if we can
         * now process any completed handshake messages
         */
        input.incomingRecord(record);

        /*
         * We don't need to create a separate delegatable task
         * for finished messages.
         */
        if ((conn != null) || expectingFinished) {
            processLoop();
        } else {
            delegateTask(new PrivilegedExceptionAction<Void>() {
                @Override
                public Void run() throws Exception {
                    processLoop();
                    return null;
                }
            });
        }
    }

    /*
     * On input, we hash messages one at a time since servers may need
     * to access an intermediate hash to validate a CertificateVerify
     * message.
     *
     * Note that many handshake messages can come in one record (and often
     * do, to reduce network resource utilization), and one message can also
     * require multiple records (e.g. very large Certificate messages).
     */
    void processLoop() throws IOException {

        // need to read off 4 bytes at least to get the handshake
        // message type and length.
        while (input.available() >= 4) {
            byte messageType;
            int messageLen;

            /*
             * See if we can read the handshake message header, and
             * then the entire handshake message.  If not, wait till
             * we can read and process an entire message.
             */
            input.mark(4);

            messageType = (byte)input.getInt8();
            messageLen = input.getInt24();

            if (input.available() < messageLen) {
                input.reset();
                return;
            }

            // Set the flags in the message receiving side.
            if (messageType == HandshakeMessage.ht_client_hello) {
                clientHelloDelivered = true;
            } else if (messageType == HandshakeMessage.ht_hello_request) {
                serverHelloRequested = true;
            }

            /*
             * Process the message.  We require
             * that processMessage() consumes the entire message.  In
             * lieu of explicit error checks (how?!) we assume that the
             * data will look like garbage on encoding/processing errors,
             * and that other protocol code will detect such errors.
             *
             * Note that digesting is normally deferred till after the
             * message has been processed, though to process at least the
             * client's Finished message (i.e. send the server's) we need
             * to acccelerate that digesting.
             *
             * Also, note that hello request messages are never hashed;
             * that includes the hello request header, too.
             */
            processMessage(messageType, messageLen);

            // Reload if this message has been reserved.
            //
            // Note: in the implementation, only certificate_verify and
            // finished messages are reserved.
            if ((messageType == HandshakeMessage.ht_finished) ||
                (messageType == HandshakeMessage.ht_certificate_verify)) {

                handshakeHash.reload();
            }
        }
    }


    
Returns true iff the handshaker has been activated.
In activated state, the handshaker may not send any messages out.
/**
     * Returns true iff the handshaker has been activated.
     *
     * In activated state, the handshaker may not send any messages out.
     */
    boolean activated() {
        return handshakeActivated;
    }

    
Returns true iff the handshaker has sent any messages.
/**
     * Returns true iff the handshaker has sent any messages.
     */
    boolean started() {
        return (serverHelloRequested || clientHelloDelivered);
    }

    /*
     * Used to kickstart the negotiation ... either writing a
     * ClientHello or a HelloRequest as appropriate, whichever
     * the subclass returns.  NOP if handshaking's already started.
     */
    void kickstart() throws IOException {
        if ((isClient && clientHelloDelivered) ||
                (!isClient && serverHelloRequested)) {
            return;
        }

        HandshakeMessage m = getKickstartMessage();
        handshakeState.update(m, resumingSession);

        if (debug != null && Debug.isOn("handshake")) {
            m.print(System.out);
        }
        m.write(output);
        output.flush();

        // Set the flags in the message delivering side.
        int handshakeType = m.messageType();
        if (handshakeType == HandshakeMessage.ht_hello_request) {
            serverHelloRequested = true;
        } else {        // HandshakeMessage.ht_client_hello
            clientHelloDelivered = true;
        }
    }

    
Both client and server modes can start handshaking; but the
message they send to do so is different.
/**
     * Both client and server modes can start handshaking; but the
     * message they send to do so is different.
     */
    abstract HandshakeMessage getKickstartMessage() throws SSLException;

    /*
     * Client and Server side protocols are each driven though this
     * call, which processes a single message and drives the appropriate
     * side of the protocol state machine (depending on the subclass).
     */
    abstract void processMessage(byte messageType, int messageLen)
        throws IOException;

    /*
     * Most alerts in the protocol relate to handshaking problems.
     * Alerts are detected as the connection reads data.
     */
    abstract void handshakeAlert(byte description) throws SSLProtocolException;

    /*
     * Sends a change cipher spec message and updates the write side
     * cipher state so that future messages use the just-negotiated spec.
     */
    void sendChangeCipherSpec(Finished mesg, boolean lastMessage)
            throws IOException {

        output.flush(); // i.e. handshake data

        /*
         * The write cipher state is protected by the connection write lock
         * so we must grab it while making the change. We also
         * make sure no writes occur between sending the ChangeCipherSpec
         * message, installing the new cipher state, and sending the
         * Finished message.
         *
         * We already hold SSLEngine/SSLSocket "this" by virtue
         * of this being called from the readRecord code.
         */
        if (conn != null) {
            conn.writeLock.lock();
            try {
                handshakeState.changeCipherSpec(false, isClient);
                conn.changeWriteCiphers();
                if (debug != null && Debug.isOn("handshake")) {
                    mesg.print(System.out);
                }

                handshakeState.update(mesg, resumingSession);
                mesg.write(output);
                output.flush();
            } finally {
                conn.writeLock.unlock();
            }
        } else {
            synchronized (engine.writeLock) {
                handshakeState.changeCipherSpec(false, isClient);
                engine.changeWriteCiphers();
                if (debug != null && Debug.isOn("handshake")) {
                    mesg.print(System.out);
                }

                handshakeState.update(mesg, resumingSession);
                mesg.write(output);
                output.flush();
            }
        }

        if (lastMessage) {
            handshakeFinished = true;
        }
    }

    void receiveChangeCipherSpec() throws IOException {
        handshakeState.changeCipherSpec(true, isClient);
    }

    /*
     * Single access point to key calculation logic.  Given the
     * pre-master secret and the nonces from client and server,
     * produce all the keying material to be used.
     */
    void calculateKeys(SecretKey preMasterSecret, ProtocolVersion version) {
        SecretKey master = calculateMasterSecret(preMasterSecret, version);
        session.setMasterSecret(master);
        calculateConnectionKeys(master);
    }

    /*
     * Calculate the master secret from its various components.  This is
     * used for key exchange by all cipher suites.
     *
     * The master secret is the catenation of three MD5 hashes, each
     * consisting of the pre-master secret and a SHA1 hash.  Those three
     * SHA1 hashes are of (different) constant strings, the pre-master
     * secret, and the nonces provided by the client and the server.
     */
    @SuppressWarnings("deprecation")
    private SecretKey calculateMasterSecret(SecretKey preMasterSecret,
            ProtocolVersion requestedVersion) {

        if (debug != null && Debug.isOn("keygen")) {
            HexDumpEncoder      dump = new HexDumpEncoder();

            System.out.println("SESSION KEYGEN:");

            System.out.println("PreMaster Secret:");
            printHex(dump, preMasterSecret.getEncoded());

            // Nonces are dumped with connection keygen, no
            // benefit to doing it twice
        }

        // What algs/params do we need to use?
        String masterAlg;
        PRF prf;

        byte majorVersion = protocolVersion.major;
        byte minorVersion = protocolVersion.minor;
        if (protocolVersion.isDTLSProtocol()) {
            // Use TLS version number for DTLS key calculation
            if (protocolVersion.v == ProtocolVersion.DTLS10.v) {
                majorVersion = ProtocolVersion.TLS11.major;
                minorVersion = ProtocolVersion.TLS11.minor;

                masterAlg = "SunTlsMasterSecret";
                prf = P_NONE;
            } else {    // DTLS 1.2
                majorVersion = ProtocolVersion.TLS12.major;
                minorVersion = ProtocolVersion.TLS12.minor;

                masterAlg = "SunTls12MasterSecret";
                prf = cipherSuite.prfAlg;
            }
        } else {
            if (protocolVersion.v >= ProtocolVersion.TLS12.v) {
                masterAlg = "SunTls12MasterSecret";
                prf = cipherSuite.prfAlg;
            } else {
                masterAlg = "SunTlsMasterSecret";
                prf = P_NONE;
            }
        }

        String prfHashAlg = prf.getPRFHashAlg();
        int prfHashLength = prf.getPRFHashLength();
        int prfBlockSize = prf.getPRFBlockSize();

        TlsMasterSecretParameterSpec spec;
        if (session.getUseExtendedMasterSecret()) {
            // reset to use the extended master secret algorithm
            masterAlg = "SunTlsExtendedMasterSecret";

            byte[] sessionHash = null;
            if (protocolVersion.useTLS12PlusSpec()) {
                sessionHash = handshakeHash.getFinishedHash();
            } else {
                // TLS 1.0/1.1, DTLS 1.0
                sessionHash = new byte[36];
                try {
                    handshakeHash.getMD5Clone().digest(sessionHash, 0, 16);
                    handshakeHash.getSHAClone().digest(sessionHash, 16, 20);
                } catch (DigestException de) {
                    throw new ProviderException(de);
                }
            }

            spec = new TlsMasterSecretParameterSpec(
                    preMasterSecret,
                    (majorVersion & 0xFF), (minorVersion & 0xFF),
                    sessionHash,
                    prfHashAlg, prfHashLength, prfBlockSize);
        } else {
            spec = new TlsMasterSecretParameterSpec(
                    preMasterSecret,
                    (majorVersion & 0xFF), (minorVersion & 0xFF),
                    clnt_random.random_bytes, svr_random.random_bytes,
                    prfHashAlg, prfHashLength, prfBlockSize);
        }

        try {
            KeyGenerator kg = JsseJce.getKeyGenerator(masterAlg);
            kg.init(spec);
            return kg.generateKey();
        } catch (InvalidAlgorithmParameterException |
                NoSuchAlgorithmException iae) {
            // unlikely to happen, otherwise, must be a provider exception
            //
            // For RSA premaster secrets, do not signal a protocol error
            // due to the Bleichenbacher attack. See comments further down.
            if (debug != null && Debug.isOn("handshake")) {
                System.out.println("RSA master secret generation error:");
                iae.printStackTrace(System.out);
            }
            throw new ProviderException(iae);

        }
    }

    /*
     * Calculate the keys needed for this connection, once the session's
     * master secret has been calculated.  Uses the master key and nonces;
     * the amount of keying material generated is a function of the cipher
     * suite that's been negotiated.
     *
     * This gets called both on the "full handshake" (where we exchanged
     * a premaster secret and started a new session) as well as on the
     * "fast handshake" (where we just resumed a pre-existing session).
     */
    @SuppressWarnings("deprecation")
    void calculateConnectionKeys(SecretKey masterKey) {
        /*
         * For both the read and write sides of the protocol, we use the
         * master to generate MAC secrets and cipher keying material.  Block
         * ciphers need initialization vectors, which we also generate.
         *
         * First we figure out how much keying material is needed.
         */
        int hashSize = cipherSuite.macAlg.size;
        boolean is_exportable = cipherSuite.exportable;
        BulkCipher cipher = cipherSuite.cipher;
        int expandedKeySize = is_exportable ? cipher.expandedKeySize : 0;

        // Which algs/params do we need to use?
        String keyMaterialAlg;
        PRF prf;

        byte majorVersion = protocolVersion.major;
        byte minorVersion = protocolVersion.minor;
        if (protocolVersion.isDTLSProtocol()) {
            // Use TLS version number for DTLS key calculation
            if (protocolVersion.v == ProtocolVersion.DTLS10.v) {
                majorVersion = ProtocolVersion.TLS11.major;
                minorVersion = ProtocolVersion.TLS11.minor;

                keyMaterialAlg = "SunTlsKeyMaterial";
                prf = P_NONE;
            } else {    // DTLS 1.2+
                majorVersion = ProtocolVersion.TLS12.major;
                minorVersion = ProtocolVersion.TLS12.minor;

                keyMaterialAlg = "SunTls12KeyMaterial";
                prf = cipherSuite.prfAlg;
            }
        } else {
            if (protocolVersion.v >= ProtocolVersion.TLS12.v) {
                keyMaterialAlg = "SunTls12KeyMaterial";
                prf = cipherSuite.prfAlg;
            } else {
                keyMaterialAlg = "SunTlsKeyMaterial";
                prf = P_NONE;
            }
        }

        String prfHashAlg = prf.getPRFHashAlg();
        int prfHashLength = prf.getPRFHashLength();
        int prfBlockSize = prf.getPRFBlockSize();

        // TLS v1.1+ and DTLS use an explicit IV in CBC cipher suites to
        // protect against the CBC attacks.  AEAD/GCM cipher suites in TLS
        // v1.2 or later use a fixed IV as the implicit part of the partially
        // implicit nonce technique described in RFC 5116.
        int ivSize = cipher.ivSize;
        if (cipher.cipherType == AEAD_CIPHER) {
            ivSize = cipher.fixedIvSize;
        } else if ((cipher.cipherType == BLOCK_CIPHER) &&
                protocolVersion.useTLS11PlusSpec()) {
            ivSize = 0;
        }

        TlsKeyMaterialParameterSpec spec = new TlsKeyMaterialParameterSpec(
                masterKey, (majorVersion & 0xFF), (minorVersion & 0xFF),
                clnt_random.random_bytes, svr_random.random_bytes,
                cipher.algorithm, cipher.keySize, expandedKeySize,
                ivSize, hashSize,
                prfHashAlg, prfHashLength, prfBlockSize);

        try {
            KeyGenerator kg = JsseJce.getKeyGenerator(keyMaterialAlg);
            kg.init(spec);
            TlsKeyMaterialSpec keySpec = (TlsKeyMaterialSpec)kg.generateKey();

            // Return null if cipher keys are not supposed to be generated.
            clntWriteKey = keySpec.getClientCipherKey();
            svrWriteKey = keySpec.getServerCipherKey();

            // Return null if IVs are not supposed to be generated.
            clntWriteIV = keySpec.getClientIv();
            svrWriteIV = keySpec.getServerIv();

            // Return null if MAC keys are not supposed to be generated.
            clntMacSecret = keySpec.getClientMacKey();
            svrMacSecret = keySpec.getServerMacKey();
        } catch (GeneralSecurityException e) {
            throw new ProviderException(e);
        }

        //
        // Dump the connection keys as they're generated.
        //
        if (debug != null && Debug.isOn("keygen")) {
            synchronized (System.out) {
                HexDumpEncoder  dump = new HexDumpEncoder();

                System.out.println("CONNECTION KEYGEN:");

                // Inputs:
                System.out.println("Client Nonce:");
                printHex(dump, clnt_random.random_bytes);
                System.out.println("Server Nonce:");
                printHex(dump, svr_random.random_bytes);
                System.out.println("Master Secret:");
                printHex(dump, masterKey.getEncoded());

                // Outputs:
                if (clntMacSecret != null) {
                    System.out.println("Client MAC write Secret:");
                    printHex(dump, clntMacSecret.getEncoded());
                    System.out.println("Server MAC write Secret:");
                    printHex(dump, svrMacSecret.getEncoded());
                } else {
                    System.out.println("... no MAC keys used for this cipher");
                }

                if (clntWriteKey != null) {
                    System.out.println("Client write key:");
                    printHex(dump, clntWriteKey.getEncoded());
                    System.out.println("Server write key:");
                    printHex(dump, svrWriteKey.getEncoded());
                } else {
                    System.out.println("... no encryption keys used");
                }

                if (clntWriteIV != null) {
                    System.out.println("Client write IV:");
                    printHex(dump, clntWriteIV.getIV());
                    System.out.println("Server write IV:");
                    printHex(dump, svrWriteIV.getIV());
                } else {
                    if (protocolVersion.useTLS11PlusSpec()) {
                        System.out.println(
                                "... no IV derived for this protocol");
                    } else {
                        System.out.println("... no IV used for this cipher");
                    }
                }
                System.out.flush();
            }
        }
    }

    private static void printHex(HexDumpEncoder dump, byte[] bytes) {
        if (bytes == null) {
            System.out.println("(key bytes not available)");
        } else {
            try {
                dump.encodeBuffer(bytes, System.out);
            } catch (IOException e) {
                // just for debugging, ignore this
            }
        }
    }

    /*
     * Implement a simple task delegator.
     *
     * We are currently implementing this as a single delegator, may
     * try for parallel tasks later.  Client Authentication could
     * benefit from this, where ClientKeyExchange/CertificateVerify
     * could be carried out in parallel.
     */
    class DelegatedTask<E> implements Runnable {

        private PrivilegedExceptionAction<E> pea;

        DelegatedTask(PrivilegedExceptionAction<E> pea) {
            this.pea = pea;
        }

        public void run() {
            synchronized (engine) {
                try {
                    AccessController.doPrivileged(pea, engine.getAcc());
                } catch (PrivilegedActionException pae) {
                    thrown = pae.getException();
                } catch (RuntimeException rte) {
                    thrown = rte;
                }
                delegatedTask = null;
                taskDelegated = false;
            }
        }
    }

    private <T> void delegateTask(PrivilegedExceptionAction<T> pea) {
        delegatedTask = new DelegatedTask<T>(pea);
        taskDelegated = false;
        thrown = null;
    }

    DelegatedTask<?> getTask() {
        if (!taskDelegated) {
            taskDelegated = true;
            return delegatedTask;
        } else {
            return null;
        }
    }

    /*
     * See if there are any tasks which need to be delegated
     *
     * Locked by SSLEngine.this.
     */
    boolean taskOutstanding() {
        return (delegatedTask != null);
    }

    /*
     * The previous caller failed for some reason, report back the
     * Exception.  We won't worry about Error's.
     *
     * Locked by SSLEngine.this.
     */
    void checkThrown() throws SSLException {
        synchronized (thrownLock) {
            if (thrown != null) {

                String msg = thrown.getMessage();

                if (msg == null) {
                    msg = "Delegated task threw Exception/Error";
                }

                /*
                 * See what the underlying type of exception is.  We should
                 * throw the same thing.  Chain thrown to the new exception.
                 */
                Exception e = thrown;
                thrown = null;

                if (e instanceof RuntimeException) {
                    throw new RuntimeException(msg, e);
                } else if (e instanceof SSLHandshakeException) {
                    throw (SSLHandshakeException)
                        new SSLHandshakeException(msg).initCause(e);
                } else if (e instanceof SSLKeyException) {
                    throw (SSLKeyException)
                        new SSLKeyException(msg).initCause(e);
                } else if (e instanceof SSLPeerUnverifiedException) {
                    throw (SSLPeerUnverifiedException)
                        new SSLPeerUnverifiedException(msg).initCause(e);
                } else if (e instanceof SSLProtocolException) {
                    throw (SSLProtocolException)
                        new SSLProtocolException(msg).initCause(e);
                } else {
                    /*
                     * If it's SSLException or any other Exception,
                     * we'll wrap it in an SSLException.
                     */
                    throw new SSLException(msg, e);
                }
            }
        }
    }
}