All Downloads are FREE. Search and download functionalities are using the official Maven repository.

com.rabbitmq.client.DnsSrvRecordAddressResolver Maven / Gradle / Ivy

Go to download

The RabbitMQ Java client library allows Java applications to interface with RabbitMQ.

There is a newer version: 5.22.0
Show newest version
// Copyright (c) 2007-Present Pivotal Software, Inc.  All rights reserved.
//
// This software, the RabbitMQ Java client library, is triple-licensed under the
// Mozilla Public License 1.1 ("MPL"), the GNU General Public License version 2
// ("GPL") and the Apache License version 2 ("ASL"). For the MPL, please see
// LICENSE-MPL-RabbitMQ. For the GPL, please see LICENSE-GPL2.  For the ASL,
// please see LICENSE-APACHE2.
//
// This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND,
// either express or implied. See the LICENSE file for specific language governing
// rights and limitations of this software.
//
// If you have any questions regarding licensing, please contact us at
// [email protected].

package com.rabbitmq.client;

import javax.naming.NamingEnumeration;
import javax.naming.NamingException;
import javax.naming.directory.Attributes;
import javax.naming.directory.DirContext;
import javax.naming.directory.InitialDirContext;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Hashtable;
import java.util.List;

/**
 * {@link AddressResolver} that resolves addresses against a DNS SRV request.
 * SRV records contain the hostname and the port for a given service.
 * They also support priorities, to give precedence to a given host
 * over other hosts.
 * Note the hosts returned by the SRV query must be resolvable by
 * the DNS servers of the underlying platform (or the default ones
 * specified for this Java process). This class does not issue a
 * query for A records after the SRV query.
 * This implementation returns the highest-priority records first.
 * This behavior can be changed by overriding the {@code sort} method.
 *
 * This implementation uses internally the {@code com.sun.jndi.dns.DnsContextFactory}
 * class for the DNS query.
 *
 * The first returned address is used when automatic recovery is NOT enabled
 * at the {@link ConnectionFactory} level.
 * When automatic recovery is enabled, a random address will be picked up
 * from the returned list of {@link Address}es.
 *
 */
public class DnsSrvRecordAddressResolver implements AddressResolver {

    /**
     * the SRV service information.
     * e.g. _sip._tcp.example.com or rabbitmq.service.consul
     */
    private final String service;

    /**
     * URLs of the DNS servers.
     * e.g. dns://server1.example.com/example.com
     * Default to {@code dns:}, that is the DNS server of the
     * underlying platform.
     */
    private final String dnsUrls;

    public DnsSrvRecordAddressResolver(String service) {
        this(service, "dns:");
    }

    public DnsSrvRecordAddressResolver(String service, String dnsUrls) {
        this.service = service;
        this.dnsUrls = dnsUrls;
    }

    @Override
    public List
getAddresses() throws IOException { List records = lookupSrvRecords(service, dnsUrls); records = sort(records); List
addresses = new ArrayList
(); for (SrvRecord record : records) { addresses.add(new Address(record.getHost(), record.getPort())); } return addresses; } protected List lookupSrvRecords(String service, String dnsUrls) throws IOException { Hashtable env = new Hashtable(); env.put("java.naming.factory.initial", "com.sun.jndi.dns.DnsContextFactory"); env.put("java.naming.provider.url", dnsUrls); List records = new ArrayList(); try { DirContext ctx = new InitialDirContext(env); Attributes attributes = ctx.getAttributes(service, new String[] { "SRV" }); NamingEnumeration servers = attributes.get("srv").getAll(); while (servers.hasMore()) { records.add(mapSrvRecord((String) servers.next())); } } catch(NamingException e) { throw new IOException("Error during DNS SRV query", e); } return records; } protected SrvRecord mapSrvRecord(String srvResult) { return SrvRecord.fromSrvQueryResult(srvResult); } protected List sort(List records) { Collections.sort(records); return records; } public static class SrvRecord implements Comparable { private final int priority; private final int weight; private final int port; private final String host; public SrvRecord(int priority, int weight, int port, String host) { this.priority = priority; this.weight = weight; this.port = port; int lastDotIndex = host.lastIndexOf("."); if(lastDotIndex > 0) { this.host = host.substring(0, lastDotIndex); } else { this.host = host; } } public int getPriority() { return priority; } public int getWeight() { return weight; } public int getPort() { return port; } public String getHost() { return host; } public static SrvRecord fromSrvQueryResult(String srvResult) { String[] fields = srvResult.split(" "); return new SrvRecord( Integer.parseInt(fields[0]), Integer.parseInt(fields[1]), Integer.parseInt(fields[2]), fields[3] ); } @Override public int compareTo(SrvRecord o) { return (this.priority < o.getPriority()) ? -1 : ((this.priority == o.getPriority()) ? 0 : 1); } } }




© 2015 - 2024 Weber Informatics LLC | Privacy Policy