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

org.xbill.DNS.spi.DNSJavaNameService Maven / Gradle / Ivy

The newest version!
// Copyright (c) 2005 Brian Wellington ([email protected])

package org.xbill.DNS.spi;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.StringTokenizer;

import org.xbill.DNS.AAAARecord;
import org.xbill.DNS.ARecord;
import org.xbill.DNS.ExtendedResolver;
import org.xbill.DNS.Lookup;
import org.xbill.DNS.Name;
import org.xbill.DNS.PTRRecord;
import org.xbill.DNS.Record;
import org.xbill.DNS.Resolver;
import org.xbill.DNS.ReverseMap;
import org.xbill.DNS.TextParseException;
import org.xbill.DNS.Type;

/**
 * This class implements a Name Service Provider, which Java can use 
 * (starting with version 1.4), to perform DNS resolutions instead of using 
 * the standard calls. 
 * 

* This Name Service Provider uses dnsjava. *

* To use this provider, you must set the following system property: * sun.net.spi.nameservice.provider.1=dns,dnsjava * * @author Brian Wellington * @author Paul Cowan ([email protected]) */ public class DNSJavaNameService implements InvocationHandler { private static final String nsProperty = "sun.net.spi.nameservice.nameservers"; private static final String domainProperty = "sun.net.spi.nameservice.domain"; private static final String v6Property = "java.net.preferIPv6Addresses"; private boolean preferV6 = false; /** * Creates a DNSJavaNameService instance. *

* Uses the * sun.net.spi.nameservice.nameservers, * sun.net.spi.nameservice.domain, and * java.net.preferIPv6Addresses properties for configuration. */ protected DNSJavaNameService() { String nameServers = System.getProperty(nsProperty); String domain = System.getProperty(domainProperty); String v6 = System.getProperty(v6Property); if (nameServers != null) { StringTokenizer st = new StringTokenizer(nameServers, ","); String [] servers = new String[st.countTokens()]; int n = 0; while (st.hasMoreTokens()) servers[n++] = st.nextToken(); try { Resolver res = new ExtendedResolver(servers); Lookup.setDefaultResolver(res); } catch (UnknownHostException e) { System.err.println("DNSJavaNameService: invalid " + nsProperty); } } if (domain != null) { try { Lookup.setDefaultSearchPath(new String[] {domain}); } catch (TextParseException e) { System.err.println("DNSJavaNameService: invalid " + domainProperty); } } if (v6 != null && v6.equalsIgnoreCase("true")) preferV6 = true; } public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { try { if (method.getName().equals("getHostByAddr")) { return this.getHostByAddr((byte[]) args[0]); } else if (method.getName().equals("lookupAllHostAddr")) { InetAddress[] addresses; addresses = this.lookupAllHostAddr((String) args[0]); Class returnType = method.getReturnType(); if (returnType.equals(InetAddress[].class)) { // method for Java >= 1.6 return addresses; } else if (returnType.equals(byte[][].class)) { // method for Java <= 1.5 int naddrs = addresses.length; byte [][] byteAddresses = new byte[naddrs][]; byte [] addr; for (int i = 0; i < naddrs; i++) { addr = addresses[i].getAddress(); byteAddresses[i] = addr; } return byteAddresses; } } } catch (Throwable e) { System.err.println("DNSJavaNameService: Unexpected error."); e.printStackTrace(); throw e; } throw new IllegalArgumentException( "Unknown function name or arguments."); } /** * Performs a forward DNS lookup for the host name. * @param host The host name to resolve. * @return All the ip addresses found for the host name. */ public InetAddress [] lookupAllHostAddr(String host) throws UnknownHostException { Name name = null; try { name = new Name(host); } catch (TextParseException e) { throw new UnknownHostException(host); } Record [] records = null; if (preferV6) records = new Lookup(name, Type.AAAA).run(); if (records == null) records = new Lookup(name, Type.A).run(); if (records == null && !preferV6) records = new Lookup(name, Type.AAAA).run(); if (records == null) throw new UnknownHostException(host); InetAddress[] array = new InetAddress[records.length]; for (int i = 0; i < records.length; i++) { Record record = records[i]; if (records[i] instanceof ARecord) { ARecord a = (ARecord) records[i]; array[i] = a.getAddress(); } else { AAAARecord aaaa = (AAAARecord) records[i]; array[i] = aaaa.getAddress(); } } return array; } /** * Performs a reverse DNS lookup. * @param addr The ip address to lookup. * @return The host name found for the ip address. */ public String getHostByAddr(byte [] addr) throws UnknownHostException { Name name = ReverseMap.fromAddress(InetAddress.getByAddress(addr)); Record [] records = new Lookup(name, Type.PTR).run(); if (records == null) throw new UnknownHostException(); return ((PTRRecord) records[0]).getTarget().toString(); } }





© 2015 - 2024 Weber Informatics LLC | Privacy Policy