/*
* Copied from the DnsJava project
*
* Copyright (c) 1998-2011, Brian Wellington.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
package io.milton.dns.spi;
import io.milton.dns.Name;
import io.milton.dns.TextParseException;
import io.milton.dns.record.AAAARecord;
import io.milton.dns.record.ARecord;
import io.milton.dns.record.ExtendedResolver;
import io.milton.dns.record.Lookup;
import io.milton.dns.record.PTRRecord;
import io.milton.dns.record.Record;
import io.milton.dns.record.Resolver;
import io.milton.dns.record.ReverseMap;
import io.milton.dns.record.Type;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.StringTokenizer;
/**
* 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. <p> This Name Service Provider uses dnsjava. <p> To use this provider,
* you must set the following system property:
* <b>sun.net.spi.nameservice.provider.1=dns,dnsjava</b>
*
* @author Brian Wellington
* @author Paul Cowan (pwc21@yahoo.com)
*/
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. <p> Uses the
* <b>sun.net.spi.nameservice.nameservers</b>,
* <b>sun.net.spi.nameservice.domain</b>, and
* <b>java.net.preferIPv6Addresses</b> 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();
}
}