/**
 * Copyright (C) 2004-2008 Jive Software. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.jivesoftware.openfire.net;

import java.security.GeneralSecurityException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.Principal;
import java.security.PublicKey;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.Date;
import java.util.Enumeration;
import java.util.List;

import javax.net.ssl.X509TrustManager;

import org.jivesoftware.openfire.Connection;
import org.jivesoftware.openfire.session.ConnectionSettings;
import org.jivesoftware.util.CertificateManager;
import org.jivesoftware.util.JiveGlobals;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * ServerTrustManager is a Trust Manager that is only used for s2s connections. This TrustManager
 * is used both when the server connects to another server as well as when receiving a connection
 * from another server. In both cases, it is possible to indicate if self-signed certificates
 * are going to be accepted. In case of accepting a self-signed certificate a warning is logged.
 * Future version of the server might include a small workflow so admins can review self-signed
 * certificates or certificates of unknown issuers and manually accept them.
 *
 * @author Gaston Dombiak
 */
public class ServerTrustManager implements X509TrustManager {

	private static final Logger Log = LoggerFactory.getLogger(ServerTrustManager.class);

    /**
     * KeyStore that holds the trusted CA
     */
    private KeyStore trustStore;
    /**
     * Holds the domain of the remote server we are trying to connect
     */
    private String server;
    /**
     * Holds the LocalIncomingServerSession that is part of the TLS negotiation.
     */
    private Connection connection;

    public ServerTrustManager(String server, KeyStore trustTrust, Connection connection) {
        super();
        this.server = server;
        this.trustStore = trustTrust;
        this.connection = connection;
    }

    @Override
    public void checkClientTrusted(X509Certificate[] x509Certificates,
            String string) {
        // Do not validate the certificate at this point. The certificate is going to be used
        // when the remote server requests to do EXTERNAL SASL
    }

    /**
     * Given the partial or complete certificate chain provided by the peer, build a certificate
     * path to a trusted root and return if it can be validated and is trusted for server SSL
     * authentication based on the authentication type. The authentication type is the key
     * exchange algorithm portion of the cipher suites represented as a String, such as "RSA",
     * "DHE_DSS". Note: for some exportable cipher suites, the key exchange algorithm is
     * determined at run time during the handshake. For instance, for
     * TLS_RSA_EXPORT_WITH_RC4_40_MD5, the authType should be RSA_EXPORT when an ephemeral
     * RSA key is used for the key exchange, and RSA when the key from the server certificate
     * is used. Checking is case-sensitive.<p>
     *
     * By default certificates are going to be verified. This includes verifying the certificate
     * chain, the root certificate and the certificates validity. However, it is possible to
     * disable certificates validation as a whole or each specific validation.
     *
     * @param x509Certificates an ordered array of peer X.509 certificates with the peer's own
     *        certificate listed first and followed by any certificate authorities.
     * @param string the key exchange algorithm used.
     * @throws CertificateException if the certificate chain is not trusted by this TrustManager.
     */
    @Override
    public void checkServerTrusted(X509Certificate[] x509Certificates, String string)
            throws CertificateException {
        // Do nothing here. As before, the certificate will be validated when the remote server authenticates.
    }

    @Override
    public X509Certificate[] getAcceptedIssuers() {
        if (JiveGlobals.getBooleanProperty(ConnectionSettings.Server.TLS_ACCEPT_SELFSIGNED_CERTS, false)) {
            // Answer an empty list since we accept any issuer
            return new X509Certificate[0];
        }
        else {
            X509Certificate[] X509Certs = null;
            try {
                // See how many certificates are in the keystore.
                int numberOfEntry = trustStore.size();
                // If there are any certificates in the keystore.
                if (numberOfEntry > 0) {
                    // Create an array of X509Certificates
                    X509Certs = new X509Certificate[numberOfEntry];

                    // Get all of the certificate alias out of the keystore.
                    Enumeration aliases = trustStore.aliases();

                    // Retrieve all of the certificates out of the keystore
                    // via the alias name.
                    int i = 0;
                    while (aliases.hasMoreElements()) {
                        X509Certs[i] =
                                (X509Certificate) trustStore.
                                        getCertificate((String) aliases.nextElement());
                        i++;
                    }

                }
            }
            catch (Exception e) {
                Log.error(e.getMessage(), e);
                X509Certs = null;
            }
            return X509Certs;
        }
    }
}
