/*

 * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.

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

 *

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

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

 * published by the Free Software Foundation.  Oracle designates this

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

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

 *

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

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

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

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

 * accompanied this code).

 *

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

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

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

 *

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

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package jdk.internal.net.http;

import java.net.InetSocketAddress;

import java.util.Arrays;

import java.util.ArrayDeque;

import java.util.List;

import java.util.concurrent.CompletableFuture;

import javax.net.ssl.SNIHostName;

import javax.net.ssl.SSLContext;

import javax.net.ssl.SSLEngine;

import javax.net.ssl.SSLParameters;

import jdk.internal.net.http.common.SSLTube;

import jdk.internal.net.http.common.Log;

import jdk.internal.net.http.common.Utils;

import static jdk.internal.net.http.common.Utils.ServerName;

/**

 * Asynchronous version of SSLConnection.

 *

 * There are two concrete implementations of this class: AsyncSSLConnection

 * and AsyncSSLTunnelConnection.

 * This abstraction is useful when downgrading from HTTP/2 to HTTP/1.1 over

 * an SSL connection. See ExchangeImpl::get in the case where an ALPNException

 * is thrown.

 *

 * Note: An AsyncSSLConnection wraps a PlainHttpConnection, while an

 *       AsyncSSLTunnelConnection wraps a PlainTunnelingConnection.

 *       If both these wrapped classes where made to inherit from a

 *       common abstraction then it might be possible to merge

 *       AsyncSSLConnection and AsyncSSLTunnelConnection back into

 *       a single class - and simply use different factory methods to

 *       create different wrappees, but this is left up for further cleanup.

 *

 */

abstract class AbstractAsyncSSLConnection extends HttpConnection

{

    protected final SSLEngine engine;

    protected final String serverName;

    protected final SSLParameters sslParameters;

    // Setting this property disables HTTPS hostname verification. Use with care.

    private static final boolean disableHostnameVerification

            = Utils.isHostnameVerificationDisabled();

    AbstractAsyncSSLConnection(InetSocketAddress addr,

                               HttpClientImpl client,

                               ServerName serverName, int port,

                               String[] alpn) {

        super(addr, client);

        this.serverName = serverName.getName();

        SSLContext context = client.theSSLContext();

        sslParameters = createSSLParameters(client, serverName, alpn);

        Log.logParams(sslParameters);

        engine = createEngine(context, serverName.getName(), port, sslParameters);

    }

    abstract SSLTube getConnectionFlow();

    final CompletableFuture<String> getALPN() {

        return getConnectionFlow().getALPN();

    }

    final SSLEngine getEngine() { return engine; }

    private static boolean contains(String[] rr, String target) {

        for (String s : rr)

            if (target.equalsIgnoreCase(s))

                return true;

        return false;

    }

    private static SSLParameters createSSLParameters(HttpClientImpl client,

                                                     ServerName serverName,

                                                     String[] alpn) {

        SSLParameters sslp = client.sslParameters();

        SSLParameters sslParameters = Utils.copySSLParameters(sslp);

        // filter out unwanted protocols, if h2 only

        if (alpn != null && alpn.length != 0 && !contains(alpn, "http/1.1")) {

            ArrayDeque<String> l = new ArrayDeque<>();

            for (String proto : sslParameters.getProtocols()) {

                if (!proto.startsWith("SSL") && !proto.endsWith("v1.1") && !proto.endsWith("v1")) {

                    l.add(proto);

                }

            }

            String[] a1 = l.toArray(new String[0]);

            sslParameters.setProtocols(a1);

        }

        if (!disableHostnameVerification)

            sslParameters.setEndpointIdentificationAlgorithm("HTTPS");

        if (alpn != null) {

            Log.logSSL("AbstractAsyncSSLConnection: Setting application protocols: {0}",

                       Arrays.toString(alpn));

            sslParameters.setApplicationProtocols(alpn);

        } else {

            Log.logSSL("AbstractAsyncSSLConnection: no applications set!");

        }

        if (!serverName.isLiteral()) {

            String name = serverName.getName();

            if (name != null && name.length() > 0) {

                sslParameters.setServerNames(List.of(new SNIHostName(name)));

            }

        }

        return sslParameters;

    }

    private static SSLEngine createEngine(SSLContext context, String serverName, int port,

                                          SSLParameters sslParameters) {

        SSLEngine engine = context.createSSLEngine(serverName, port);

        engine.setUseClientMode(true);

        engine.setSSLParameters(sslParameters);

        return engine;

    }

    @Override

    final boolean isSecure() {

        return true;

    }

}