/*

 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package sun.security.ssl;

import java.io.IOException;

import java.security.cert.X509Certificate;

import sun.security.ssl.ClientHello.ClientHelloMessage;

class ClientHandshakeContext extends HandshakeContext {

    /*

     * Allow unsafe server certificate change?

     *

     * Server certificate change during SSL/TLS renegotiation may be considered

     * unsafe, as described in the Triple Handshake attacks:

     *

     *     https://secure-resumption.com/tlsauth.pdf

     *

     * Endpoint identification (See

     * SSLParameters.getEndpointIdentificationAlgorithm()) is a pretty nice

     * guarantee that the server certificate change in renegotiation is legal.

     * However, endpoint identification is only enabled for HTTPS and LDAP

     * over SSL/TLS by default.  It is not enough to protect SSL/TLS

     * connections other than HTTPS and LDAP.

     *

     * The renegotiation indication extension (See RFC 5746) is a pretty

     * strong guarantee that the endpoints on both client and server sides

     * are identical on the same connection.  However, the Triple Handshake

     * attacks can bypass this guarantee if there is a session-resumption

     * handshake between the initial full handshake and the renegotiation

     * full handshake.

     *

     * Server certificate change may be unsafe and should be restricted if

     * endpoint identification is not enabled and the previous handshake is

     * a session-resumption abbreviated initial handshake, unless the

     * identities represented by both certificates can be regraded as the

     * same (See isIdentityEquivalent()).

     *

     * Considering the compatibility impact and the actual requirements to

     * support server certificate change in practice, the system property,

     * jdk.tls.allowUnsafeServerCertChange, is used to define whether unsafe

     * server certificate change in renegotiation is allowed or not.  The

     * default value of the system property is "false".  To mitigate the

     * compatibility impact, applications may want to set the system

     * property to "true" at their own risk.

     *

     * If the value of the system property is "false", server certificate

     * change in renegotiation after a session-resumption abbreviated initial

     * handshake is restricted (See isIdentityEquivalent()).

     *

     * If the system property is set to "true" explicitly, the restriction on

     * server certificate change in renegotiation is disabled.

     */

    static final boolean allowUnsafeServerCertChange =

            Utilities.getBooleanProperty(

                    "jdk.tls.allowUnsafeServerCertChange", false);

    /*

     * the reserved server certificate chain in previous handshaking

     *

     * The server certificate chain is only reserved if the previous

     * handshake is a session-resumption abbreviated initial handshake.

     */

    X509Certificate[] reservedServerCerts = null;

    X509Certificate[] deferredCerts;

    ClientHelloMessage initialClientHelloMsg = null;

    ClientHandshakeContext(SSLContextImpl sslContext,

            TransportContext conContext) throws IOException {

        super(sslContext, conContext);

    }

    @Override

    void kickstart() throws IOException {

        if (kickstartMessageDelivered) {

            return;

        }

        SSLHandshake.kickstart(this);

        kickstartMessageDelivered = true;

    }

}