kerby-kerb/kerb-simplekdc/src/main/java/org/apache/kerby/kerberos/kerb/client/Krb5Conf.java

/**
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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.apache.kerby.kerberos.kerb.client;

import org.apache.kerby.kerberos.kerb.server.KdcSetting;
import org.apache.kerby.kerberos.kerb.server.SimpleKdcServer;
import org.apache.kerby.util.IOUtil;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;

/**
 * Generate krb5 file using given kdc server settings.
 */
public class Krb5Conf {
    public static final String KRB5_CONF = "java.security.krb5.conf";
    private static final String KRB5_CONF_FILE = "krb5.conf";
    private SimpleKdcServer kdcServer;
    private File confFile;

    public Krb5Conf(SimpleKdcServer kdcServer) {
        this.kdcServer = kdcServer;
    }

    public void initKrb5conf() throws IOException {
        File confFile = generateConfFile();
        System.setProperty(KRB5_CONF, confFile.getAbsolutePath());
    }

    // Read in krb5.conf and substitute in the correct port
    private File generateConfFile() throws IOException {
        KdcSetting setting = kdcServer.getKdcSetting();

        String resourcePath = setting.allowUdp() ? "/krb5_udp-template.conf" : "/krb5-template.conf";
        String templateContent;
        try (InputStream templateResource = getClass().getResourceAsStream(resourcePath)) {
            templateContent = IOUtil.readInput(templateResource);
        }

        String content = templateContent;

        content = content.replaceAll("_REALM_", "" + setting.getKdcRealm());

        int kdcPort = setting.allowUdp() ? setting.getKdcUdpPort()
                : setting.getKdcTcpPort();
        content = content.replaceAll("_KDC_PORT_",
                String.valueOf(kdcPort));

        if (setting.allowTcp()) {
            content = content.replaceAll("#_KDC_TCP_PORT_", "kdc_tcp_port = " + setting.getKdcTcpPort());
        }
        if (setting.allowUdp()) {
            content = content.replaceAll("#_KDC_UDP_PORT_", "kdc_udp_port = " + setting.getKdcUdpPort());
        }

        int udpLimit = setting.allowUdp() ? 4096 : 1;
        content = content.replaceAll("_UDP_LIMIT_", String.valueOf(udpLimit));

        this.confFile = new File(kdcServer.getWorkDir(), KRB5_CONF_FILE);
        IOUtil.writeFile(content, confFile);

        return confFile;
    }

    public void deleteKrb5conf() throws IOException {
        if (!this.confFile.delete()) {
            throw new IOException();
        }
    }
}