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Microsoft JDBC Driver for SQL Server. The Azure Key Vault feature in Microsoft JDBC Driver for SQL Server depends on Azure SDK for JAVA and Azure Active Directory Library For Java.

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/*
 * Microsoft JDBC Driver for SQL Server
 * 
 * Copyright(c) Microsoft Corporation All rights reserved.
 * 
 * This program is made available under the terms of the MIT License. See the LICENSE file in the project root for more information.
 */
package com.microsoft.sqlserver.jdbc.dns;

import java.util.Hashtable;
import java.util.Set;
import java.util.TreeSet;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.naming.NamingEnumeration;
import javax.naming.NamingException;
import javax.naming.directory.Attribute;
import javax.naming.directory.Attributes;
import javax.naming.directory.DirContext;
import javax.naming.directory.InitialDirContext;

public class DNSUtilities {

    private final static Logger LOG = Logger.getLogger(DNSUtilities.class.getName());

    private static final Level DNS_ERR_LOG_LEVEL = Level.FINE;

    /**
     * Find all SRV Record using DNS.
     *
     * @param dnsSrvRecordToFind
     *            the DNS record, for instance: _ldap._tcp.dc._msdcs.DOMAIN.COM to find all LDAP servers in DOMAIN.COM
     * @return the collection of records with facilities to find the best candidate
     * @throws NamingException
     *             if DNS is not available
     */
    public static Set findSrvRecords(final String dnsSrvRecordToFind) throws NamingException {
        Hashtable env = new Hashtable<>();
        env.put("java.naming.factory.initial", "com.sun.jndi.dns.DnsContextFactory");
        env.put("java.naming.provider.url", "dns:");
        DirContext ctx = new InitialDirContext(env);
        Attributes attrs = ctx.getAttributes(dnsSrvRecordToFind, new String[] {"SRV"});
        NamingEnumeration allServers = attrs.getAll();
        TreeSet records = new TreeSet<>();
        while (allServers.hasMoreElements()) {
            Attribute a = allServers.nextElement();
            NamingEnumeration srvRecord = a.getAll();
            while (srvRecord.hasMore()) {
                final String record = String.valueOf(srvRecord.nextElement());
                try {
                    DNSRecordSRV rec = DNSRecordSRV.parseFromDNSRecord(record);
                    if (rec != null) {
                        records.add(rec);
                    }
                }
                catch (IllegalArgumentException errorParsingRecord) {
                    if (LOG.isLoggable(DNS_ERR_LOG_LEVEL)) {
                        LOG.log(DNS_ERR_LOG_LEVEL, String.format("Failed to parse SRV DNS Record: '%s'", record), errorParsingRecord);
                    }
                }
            }
            srvRecord.close();
        }
        allServers.close();
        return records;
    }
}