/*
* $Id$
*
* Copyright (C) 2003-2014 JNode.org
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; If not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package org.jnode.net.ipv4.util;
import java.net.UnknownHostException;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.HashMap;
import java.util.Map;
import java.util.Collection;
import org.jnode.driver.net.NetworkException;
import org.jnode.net.ProtocolAddress;
import org.jnode.net.Resolver;
import org.jnode.net.ipv4.IPv4Address;
import org.jnode.annotation.SharedStatics;
import org.xbill.DNS.ExtendedResolver;
import org.xbill.DNS.Lookup;
import org.xbill.DNS.Record;
import org.xbill.DNS.SimpleResolver;
import org.xbill.DNS.TextParseException;
/**
* @author Martin Hartvig
*/
@SharedStatics
public class ResolverImpl implements Resolver {
// FIXME ... upgrade to a more recent version of xbill?
// FIXME ... this class looks like it is supposed to implement
// the Singleton pattern. So how come the management methods
// and a lot of the state is 'static'?
private static ExtendedResolver resolver;
private static Map<String, org.xbill.DNS.Resolver> resolvers;
private static Map<String, ProtocolAddress[]> hosts;
private static Resolver res = null;
static {
// FIXME should this come from a hosts file?
hosts = new HashMap<String, ProtocolAddress[]>();
final String localhost = "localhost";
ProtocolAddress[] protocolAddresses = new ProtocolAddress[] {new IPv4Address("127.0.0.1")};
hosts.put(localhost, protocolAddresses);
resolvers = new HashMap<String, org.xbill.DNS.Resolver>();
}
private ResolverImpl() {
}
/**
* Singleton
*
* @return the singleton of the resolver
*/
public static Resolver getInstance() {
if (res == null) {
// FIXME ... do we REALLY have to do this???
AccessController.doPrivileged(new PrivilegedAction<Object>() {
public Object run() {
System.setProperty("dns.server", "127.0.0.1");
System.setProperty("dns.search", "localdomain");
return null;
}
});
res = new ResolverImpl();
}
return res;
}
/**
* Get list all the dns servers
*/
public static Collection<String> getDnsServers() {
return resolvers.keySet();
}
/**
* Add a dns server
*
* @param _dnsserver
* @throws NetworkException
*/
public static void addDnsServer(ProtocolAddress _dnsserver) throws NetworkException {
try {
if (resolver == null) {
final String[] server = new String[] {_dnsserver.toString()};
try {
AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
public Object run() throws Exception {
resolver = new ExtendedResolver(server);
Lookup.setDefaultResolver(resolver);
return null;
}
});
} catch (PrivilegedActionException x) {
Exception ee = x.getException();
if (ee instanceof UnknownHostException) {
throw (UnknownHostException) ee;
} else {
throw new RuntimeException(ee);
}
}
resolvers.put(_dnsserver.toString(), resolver);
}
} catch (UnknownHostException e) {
throw new NetworkException("Can't add DNS server", e);
}
try {
String key = _dnsserver.toString();
if (!resolvers.containsKey(key)) {
SimpleResolver simpleResolver = new SimpleResolver(key);
resolver.addResolver(simpleResolver);
resolvers.put(key, simpleResolver);
}
} catch (UnknownHostException e) {
throw new NetworkException("Can't add DNS server", e);
}
}
/**
* removes a dns server
*
* @param _dnsserver
*/
public static void removeDnsServer(ProtocolAddress _dnsserver) {
if (resolver == null) {
return;
}
String key = _dnsserver.toString();
if (resolvers.containsKey(key)) {
org.xbill.DNS.Resolver resolv = resolvers.remove(key);
if (resolver.getResolvers().length == 1) {
resolver = null;
} else {
resolver.deleteResolver(resolv);
}
}
}
/**
* Get from hosts file.
*
* @param _hostname
* @return
*/
private ProtocolAddress[] getFromHostsFile(String _hostname) {
// FIXME ... check for changes to the hosts file?
return (ProtocolAddress[]) hosts.get(_hostname);
}
/**
* Gets the address(es) of the given hostname.
*
* @param hostname
* @return All addresses of the given hostname. The returned array is at
* least 1 address long.
* @throws java.net.UnknownHostException
*/
public ProtocolAddress[] getByName(final String hostname) throws UnknownHostException {
if (hostname == null) {
throw new UnknownHostException("null");
}
if (hostname.equals("*")) {
// FIXME ... why is this a special case? Comment please or fix it.
throw new UnknownHostException("*");
}
if (resolver == null) {
throw new UnknownHostException(hostname);
}
final PrivilegedExceptionAction<ProtocolAddress[]> action =
new PrivilegedExceptionAction<ProtocolAddress[]>() {
public ProtocolAddress[] run() throws UnknownHostException {
ProtocolAddress[] protocolAddresses;
// FIXME ... hard-wired policy that 'hosts' file would
// be consulted
// first. Should be configurable.
protocolAddresses = getFromHostsFile(hostname);
if (protocolAddresses != null) {
return protocolAddresses;
}
Lookup.setDefaultResolver(resolver);
final Lookup lookup;
try {
lookup = new Lookup(hostname);
} catch (TextParseException e) {
throw new UnknownHostException(hostname);
}
lookup.run();
if (lookup.getResult() == Lookup.SUCCESSFUL) {
final Record[] records = lookup.getAnswers();
final int recordCount = records.length;
protocolAddresses = new ProtocolAddress[recordCount];
for (int i = 0; i < recordCount; i++) {
final Record record = records[i];
protocolAddresses[i] = new IPv4Address(record.rdataToString());
}
} else {
throw new UnknownHostException(lookup.getErrorString());
}
return protocolAddresses;
}
};
try {
return AccessController.doPrivileged(action);
} catch (PrivilegedActionException ex) {
if (ex.getException() instanceof UnknownHostException) {
throw (UnknownHostException) ex.getException();
} else {
throw (UnknownHostException) new UnknownHostException().initCause(ex.getException());
}
}
}
/**
* Gets the hostname of the given address.
*
* @param address
* @return All hostnames of the given hostname. The returned array is at
* least 1 hostname long.
* @throws java.net.UnknownHostException
*/
public String[] getByAddress(ProtocolAddress address) throws UnknownHostException {
// FIXME ... implement this method properly.
return new String[0];
}
}