Java tutorial
/******************************************************************************* * This file is part of OpenNMS(R). * * Copyright (C) 2011-2012 The OpenNMS Group, Inc. * OpenNMS(R) is Copyright (C) 1999-2012 The OpenNMS Group, Inc. * * OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc. * * This file is a derivative work, containing both original code, included code, * and modified code that was published under the GNU General Public License. * * Original code Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org) * * Refactored from DNSServer in the JDNSS server * http://sourceforge.net/projects/jdnss/ * * Project site for JDNSS says "BSD and GPL license" but this file had no * specifics about which license it's specifically under, so assume the more * restrictive GPL until we can get more details. * * OpenNMS(R) is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published * by the Free Software Foundation, either version 3 of the License, * or (at your option) any later version. * * OpenNMS(R) 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 General Public License for more details. * * You should have received a copy of the GNU General Public License * along with OpenNMS(R). If not, see: * http://www.gnu.org/licenses/ * * For more information contact: * OpenNMS(R) Licensing <license@opennms.org> * http://www.opennms.org/ * http://www.opennms.com/ *******************************************************************************/ package org.opennms.core.test.dns; import java.io.BufferedReader; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.InterruptedIOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; import java.net.ServerSocket; import java.net.Socket; import java.net.SocketTimeoutException; import java.net.UnknownHostException; import java.util.ArrayList; import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map; import java.util.StringTokenizer; import java.util.concurrent.CountDownLatch; import org.apache.commons.io.IOUtils; import org.opennms.core.utils.InetAddressUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.xbill.DNS.Address; import org.xbill.DNS.CNAMERecord; import org.xbill.DNS.Cache; import org.xbill.DNS.Credibility; import org.xbill.DNS.DClass; import org.xbill.DNS.DNAMERecord; import org.xbill.DNS.ExtendedFlags; import org.xbill.DNS.Flags; import org.xbill.DNS.Header; import org.xbill.DNS.Message; import org.xbill.DNS.Name; import org.xbill.DNS.NameTooLongException; import org.xbill.DNS.OPTRecord; import org.xbill.DNS.Opcode; import org.xbill.DNS.RRset; import org.xbill.DNS.Rcode; import org.xbill.DNS.Record; import org.xbill.DNS.Section; import org.xbill.DNS.SetResponse; import org.xbill.DNS.TSIG; import org.xbill.DNS.TSIGRecord; import org.xbill.DNS.Type; import org.xbill.DNS.Zone; import org.xbill.DNS.ZoneTransferException; public class DNSServer { private static final Logger LOG = LoggerFactory.getLogger(DNSServer.class); private static final int DEFAULT_SOCKET_TIMEOUT = 100; private final class TCPListener implements Stoppable { private final int m_port; private final InetAddress m_addr; private ServerSocket m_socket; private volatile boolean m_stopped = false; private CountDownLatch m_startingLatch = new CountDownLatch(1); private CountDownLatch m_runningLatch = new CountDownLatch(1); private TCPListener(final int port, final InetAddress addr) { m_port = port; m_addr = addr; } @Override public void await() throws InterruptedException { m_startingLatch.await(); } @Override public void run() { try { m_socket = new ServerSocket(m_port, 128, m_addr); m_socket.setSoTimeout(DEFAULT_SOCKET_TIMEOUT); m_startingLatch.countDown(); while (!m_stopped) { try { final Socket s = m_socket.accept(); final Thread t = new Thread(new Runnable() { @Override public void run() { InputStream is = null; DataInputStream dataIn = null; DataOutputStream dataOut = null; try { try { is = s.getInputStream(); dataIn = new DataInputStream(is); final int inLength = dataIn.readUnsignedShort(); final byte[] in = new byte[inLength]; dataIn.readFully(in); final Message query; byte[] response = null; try { query = new Message(in); LOG.debug("received query: {}", query); response = generateReply(query, in, in.length, s); } catch (final IOException e) { response = formerrMessage(in); } LOG.debug("returned response: {}", response == null ? null : new Message(response)); if (response != null) { dataOut = new DataOutputStream(s.getOutputStream()); dataOut.writeShort(response.length); dataOut.write(response); } } catch (final SocketTimeoutException e) { throw e; } catch (final IOException e) { LOG.warn("error while processing socket", e); } finally { IOUtils.closeQuietly(s); IOUtils.closeQuietly(dataOut); IOUtils.closeQuietly(dataIn); IOUtils.closeQuietly(is); } } catch (final SocketTimeoutException e) { LOG.trace("timed out waiting for request", e); } } }); t.start(); } catch (final SocketTimeoutException e) { LOG.trace("timed out waiting for request", e); } } } catch (final IOException e) { LOG.warn("unable to serve socket on {}", addrport(m_addr, m_port), e); } finally { try { m_socket.close(); } catch (final IOException e) { LOG.debug("error while closing socket", e); } m_runningLatch.countDown(); } } @Override public void stop() { m_stopped = true; try { m_runningLatch.await(); } catch (final InterruptedException e) { LOG.warn("interrupted while stopping TCP listener", e); Thread.currentThread().interrupt(); } } } private final class UDPListener implements Stoppable { private final int m_port; private final InetAddress m_addr; private volatile boolean m_stopped = false; private CountDownLatch m_startingLatch = new CountDownLatch(1); private CountDownLatch m_runningLatch = new CountDownLatch(1); private UDPListener(int port, InetAddress addr) { m_port = port; m_addr = addr; } @Override public void await() throws InterruptedException { m_startingLatch.await(); } @Override public void run() { DatagramSocket sock = null; try { sock = new DatagramSocket(m_port, m_addr); sock.setSoTimeout(DEFAULT_SOCKET_TIMEOUT); final short udpLength = 512; byte[] in = new byte[udpLength]; final DatagramPacket indp = new DatagramPacket(in, in.length); DatagramPacket outdp = null; m_startingLatch.countDown(); while (!m_stopped) { indp.setLength(in.length); try { sock.receive(indp); } catch (final InterruptedIOException e) { continue; } final Message query; byte[] response = null; try { query = new Message(in); response = generateReply(query, in, indp.getLength(), null); if (response == null) continue; } catch (final IOException e) { response = formerrMessage(in); } if (outdp == null) outdp = new DatagramPacket(response, response.length, indp.getAddress(), indp.getPort()); else { outdp.setData(response); outdp.setLength(response.length); outdp.setAddress(indp.getAddress()); outdp.setPort(indp.getPort()); } sock.send(outdp); } } catch (final IOException e) { LOG.warn("error in the UDP listener: {}", addrport(m_addr, m_port), e); } finally { if (sock != null) { try { sock.close(); } catch (final Exception e) { LOG.debug("error while closing socket", e); } } m_runningLatch.countDown(); } } @Override public void stop() { m_stopped = true; try { m_runningLatch.await(); } catch (final InterruptedException e) { LOG.warn("interrupted while waiting for server to stop", e); Thread.currentThread().interrupt(); } } } static final int FLAG_DNSSECOK = 1; static final int FLAG_SIGONLY = 2; final Map<Integer, Cache> m_caches = new HashMap<Integer, Cache>(); final Map<Name, Zone> m_znames = new HashMap<Name, Zone>(); final Map<Name, TSIG> m_TSIGs = new HashMap<Name, TSIG>(); final List<Integer> m_ports = new ArrayList<Integer>(); final List<InetAddress> m_addresses = new ArrayList<InetAddress>(); final List<Stoppable> m_activeListeners = new ArrayList<Stoppable>(); private static String addrport(final InetAddress addr, final int port) { return InetAddressUtils.str(addr) + "#" + port; } public DNSServer(final String conffile) throws IOException, ZoneTransferException, ConfigurationException { parseConfiguration(conffile); } public DNSServer() throws UnknownHostException { } public void start() throws UnknownHostException { initializeDefaults(); for (final InetAddress addr : m_addresses) { for (final Integer port : m_ports) { try { final UDPListener udpListener = new UDPListener(port, addr); final Thread udpThread = new Thread(udpListener); udpThread.start(); m_activeListeners.add(udpListener); final TCPListener tcpListener = new TCPListener(port, addr); final Thread tcpThread = new Thread(tcpListener); tcpThread.start(); m_activeListeners.add(tcpListener); udpListener.await(); tcpListener.await(); LOG.info("listening on {}", addrport(addr, port)); } catch (final Exception e) { throw new RuntimeException( "Failed to start DNS server on " + InetAddressUtils.str(addr) + "/" + port, e); } } } LOG.debug("finished starting up"); } public void stop() { for (final Stoppable listener : m_activeListeners) { LOG.debug("stopping {}", listener); listener.stop(); LOG.debug("stopped {}", listener); } } protected void parseConfiguration(final String conffile) throws ConfigurationException, IOException, ZoneTransferException, UnknownHostException { final FileInputStream fs; final InputStreamReader isr; final BufferedReader br; try { fs = new FileInputStream(conffile); isr = new InputStreamReader(fs); br = new BufferedReader(isr); } catch (final Exception e) { LOG.error("Cannot open {}", conffile, e); throw new ConfigurationException("unable to read from " + conffile, e); } try { String line = null; while ((line = br.readLine()) != null) { final StringTokenizer st = new StringTokenizer(line); if (!st.hasMoreTokens()) { continue; } final String keyword = st.nextToken(); if (!st.hasMoreTokens()) { LOG.warn("unable to parse line: {}", line); continue; } if (keyword.charAt(0) == '#') { continue; } if (keyword.equals("primary")) { addPrimaryZone(st.nextToken(), st.nextToken()); } else if (keyword.equals("secondary")) { addSecondaryZone(st.nextToken(), st.nextToken()); } else if (keyword.equals("cache")) { final Cache cache = new Cache(st.nextToken()); m_caches.put(Integer.valueOf(DClass.IN), cache); } else if (keyword.equals("key")) { final String s1 = st.nextToken(); final String s2 = st.nextToken(); if (st.hasMoreTokens()) { addTSIG(s1, s2, st.nextToken()); } else { addTSIG("hmac-md5", s1, s2); } } else if (keyword.equals("port")) { m_ports.add(Integer.valueOf(st.nextToken())); } else if (keyword.equals("address")) { final String addr = st.nextToken(); m_addresses.add(Address.getByAddress(addr)); } else { LOG.warn("unknown keyword: {}", keyword); } } } finally { fs.close(); } } protected void initializeDefaults() throws UnknownHostException { if (m_ports.size() == 0) { m_ports.add(Integer.valueOf(53)); } if (m_addresses.size() == 0) { m_addresses.add(Address.getByAddress("0.0.0.0")); } } public void addPort(final int port) { m_ports.add(port); } public void setPorts(final List<Integer> ports) { if (m_ports == ports) return; m_ports.clear(); m_ports.addAll(ports); } public void addAddress(final InetAddress address) { m_addresses.add(address); } public void setAddresses(final List<InetAddress> addresses) { if (m_addresses == addresses) return; m_addresses.clear(); m_addresses.addAll(addresses); } public void addZone(final Zone zone) { m_znames.put(zone.getOrigin(), zone); } public void addPrimaryZone(final String zname, final String zonefile) throws IOException { Name origin = null; if (zname != null) origin = Name.fromString(zname, Name.root); final Zone newzone = new Zone(origin, zonefile); m_znames.put(newzone.getOrigin(), newzone); } public void addSecondaryZone(final String zone, final String remote) throws IOException, ZoneTransferException { final Name zname = Name.fromString(zone, Name.root); final Zone newzone = new Zone(zname, DClass.IN, remote); m_znames.put(zname, newzone); } public void addTSIG(final String algstr, final String namestr, final String key) throws IOException { final Name name = Name.fromString(namestr, Name.root); m_TSIGs.put(name, new TSIG(algstr, namestr, key)); } public Cache getCache(final int dclass) { Cache c = m_caches.get(dclass); if (c == null) { c = new Cache(dclass); m_caches.put(Integer.valueOf(dclass), c); } return c; } public Zone findBestZone(final Name name) { Zone foundzone = m_znames.get(name); if (foundzone != null) { return foundzone; } final int labels = name.labels(); for (int i = 1; i < labels; i++) { final Name tname = new Name(name, i); foundzone = m_znames.get(tname); if (foundzone != null) { return foundzone; } } return null; } public RRset findExactMatch(final Name name, final int type, final int dclass, final boolean glue) { final Zone zone = findBestZone(name); if (zone != null) { return zone.findExactMatch(name, type); } else { final RRset[] rrsets; final Cache cache = getCache(dclass); if (glue) { rrsets = cache.findAnyRecords(name, type); } else { rrsets = cache.findRecords(name, type); } if (rrsets == null) { return null; } else { return rrsets[0]; /* not quite right */ } } } void addRRset(final Name name, final Message response, final RRset rrset, final int section, final int flags) { for (int s = 1; s <= section; s++) { if (response.findRRset(name, rrset.getType(), s)) return; } if ((flags & FLAG_SIGONLY) == 0) { @SuppressWarnings("unchecked") final Iterator<Record> it = rrset.rrs(); while (it.hasNext()) { final Record r = it.next(); if (r.getName().isWild() && !name.isWild()) { response.addRecord(r.withName(name), section); } else { response.addRecord(r, section); } } } if ((flags & (FLAG_SIGONLY | FLAG_DNSSECOK)) != 0) { @SuppressWarnings("unchecked") final Iterator<Record> it = rrset.sigs(); while (it.hasNext()) { final Record r = it.next(); if (r.getName().isWild() && !name.isWild()) { response.addRecord(r.withName(name), section); } else { response.addRecord(r, section); } } } } private final void addSOA(final Message response, final Zone zone) { response.addRecord(zone.getSOA(), Section.AUTHORITY); } private final void addNS(final Message response, final Zone zone, final int flags) { final RRset nsRecords = zone.getNS(); addRRset(nsRecords.getName(), response, nsRecords, Section.AUTHORITY, flags); } private final void addCacheNS(final Message response, final Cache cache, final Name name) { final SetResponse sr = cache.lookupRecords(name, Type.NS, Credibility.HINT); if (!sr.isDelegation()) return; final RRset nsRecords = sr.getNS(); @SuppressWarnings("unchecked") final Iterator<Record> it = nsRecords.rrs(); while (it.hasNext()) { final Record r = it.next(); response.addRecord(r, Section.AUTHORITY); } } private void addGlue(final Message response, final Name name, final int flags) { final RRset a = findExactMatch(name, Type.A, DClass.IN, true); if (a == null) return; addRRset(name, response, a, Section.ADDITIONAL, flags); } private void addAdditional2(final Message response, final int section, final int flags) { final Record[] records = response.getSectionArray(section); for (int i = 0; i < records.length; i++) { final Record r = records[i]; final Name glueName = r.getAdditionalName(); if (glueName != null) addGlue(response, glueName, flags); } } private final void addAdditional(final Message response, final int flags) { addAdditional2(response, Section.ANSWER, flags); addAdditional2(response, Section.AUTHORITY, flags); } byte addAnswer(final Message response, final Name name, int type, int dclass, int iterations, int flags) { SetResponse sr; byte rcode = Rcode.NOERROR; if (iterations > 6) return Rcode.NOERROR; if (type == Type.SIG || type == Type.RRSIG) { type = Type.ANY; flags |= FLAG_SIGONLY; } final Zone zone = findBestZone(name); if (zone != null) sr = zone.findRecords(name, type); else { sr = getCache(dclass).lookupRecords(name, type, Credibility.NORMAL); } if (sr.isUnknown()) { addCacheNS(response, getCache(dclass), name); } if (sr.isNXDOMAIN()) { response.getHeader().setRcode(Rcode.NXDOMAIN); if (zone != null) { addSOA(response, zone); if (iterations == 0) response.getHeader().setFlag(Flags.AA); } rcode = Rcode.NXDOMAIN; } else if (sr.isNXRRSET()) { if (zone != null) { addSOA(response, zone); if (iterations == 0) response.getHeader().setFlag(Flags.AA); } } else if (sr.isDelegation()) { final RRset nsRecords = sr.getNS(); addRRset(nsRecords.getName(), response, nsRecords, Section.AUTHORITY, flags); } else if (sr.isCNAME()) { final CNAMERecord cname = sr.getCNAME(); addRRset(name, response, new RRset(cname), Section.ANSWER, flags); if (zone != null && iterations == 0) response.getHeader().setFlag(Flags.AA); rcode = addAnswer(response, cname.getTarget(), type, dclass, iterations + 1, flags); } else if (sr.isDNAME()) { final DNAMERecord dname = sr.getDNAME(); RRset rrset = new RRset(dname); addRRset(name, response, rrset, Section.ANSWER, flags); final Name newname; try { newname = name.fromDNAME(dname); } catch (final NameTooLongException e) { return Rcode.YXDOMAIN; } rrset = new RRset(new CNAMERecord(name, dclass, 0, newname)); addRRset(name, response, rrset, Section.ANSWER, flags); if (zone != null && iterations == 0) response.getHeader().setFlag(Flags.AA); rcode = addAnswer(response, newname, type, dclass, iterations + 1, flags); } else if (sr.isSuccessful()) { final RRset[] rrsets = sr.answers(); for (int i = 0; i < rrsets.length; i++) addRRset(name, response, rrsets[i], Section.ANSWER, flags); if (zone != null) { addNS(response, zone, flags); if (iterations == 0) response.getHeader().setFlag(Flags.AA); } else addCacheNS(response, getCache(dclass), name); } return rcode; } byte[] doAXFR(final Name name, final Message query, final TSIG tsig, TSIGRecord qtsig, final Socket s) { final Zone zone = m_znames.get(name); boolean first = true; if (zone == null) return errorMessage(query, Rcode.REFUSED); @SuppressWarnings("unchecked") final Iterator<RRset> it = zone.AXFR(); try { final DataOutputStream dataOut = new DataOutputStream(s.getOutputStream()); int id = query.getHeader().getID(); while (it.hasNext()) { final RRset rrset = it.next(); final Message response = new Message(id); final Header header = response.getHeader(); header.setFlag(Flags.QR); header.setFlag(Flags.AA); addRRset(rrset.getName(), response, rrset, Section.ANSWER, FLAG_DNSSECOK); if (tsig != null) { tsig.applyStream(response, qtsig, first); qtsig = response.getTSIG(); } first = false; final byte[] out = response.toWire(); dataOut.writeShort(out.length); dataOut.write(out); } } catch (final IOException ex) { LOG.warn("AXFR failed", ex); } try { s.close(); } catch (final IOException ex) { LOG.warn("error closing socket", ex); } return null; } /* * Note: a null return value means that the caller doesn't need to do * anything. Currently this only happens if this is an AXFR request over * TCP. */ byte[] generateReply(final Message query, final byte[] in, final int length, final Socket s) throws IOException { final Header header = query.getHeader(); int maxLength; int flags = 0; if (header.getFlag(Flags.QR)) return null; if (header.getRcode() != Rcode.NOERROR) return errorMessage(query, Rcode.FORMERR); if (header.getOpcode() != Opcode.QUERY) return errorMessage(query, Rcode.NOTIMP); final Record queryRecord = query.getQuestion(); final TSIGRecord queryTSIG = query.getTSIG(); TSIG tsig = null; if (queryTSIG != null) { tsig = m_TSIGs.get(queryTSIG.getName()); if (tsig == null || tsig.verify(query, in, length, null) != Rcode.NOERROR) return formerrMessage(in); } final OPTRecord queryOPT = query.getOPT(); if (s != null) maxLength = 65535; else if (queryOPT != null) maxLength = Math.max(queryOPT.getPayloadSize(), 512); else maxLength = 512; if (queryOPT != null && (queryOPT.getFlags() & ExtendedFlags.DO) != 0) flags = FLAG_DNSSECOK; final Message response = new Message(query.getHeader().getID()); response.getHeader().setFlag(Flags.QR); if (query.getHeader().getFlag(Flags.RD)) { response.getHeader().setFlag(Flags.RD); } response.addRecord(queryRecord, Section.QUESTION); final Name name = queryRecord.getName(); final int type = queryRecord.getType(); final int dclass = queryRecord.getDClass(); if ((type == Type.AXFR || type == Type.IXFR) && s != null) return doAXFR(name, query, tsig, queryTSIG, s); if (!Type.isRR(type) && type != Type.ANY) return errorMessage(query, Rcode.NOTIMP); final byte rcode = addAnswer(response, name, type, dclass, 0, flags); if (rcode != Rcode.NOERROR && rcode != Rcode.NXDOMAIN) return errorMessage(query, rcode); addAdditional(response, flags); if (queryOPT != null) { final int optflags = (flags == FLAG_DNSSECOK) ? ExtendedFlags.DO : 0; final OPTRecord opt = new OPTRecord((short) 4096, rcode, (byte) 0, optflags); response.addRecord(opt, Section.ADDITIONAL); } response.setTSIG(tsig, Rcode.NOERROR, queryTSIG); return response.toWire(maxLength); } byte[] buildErrorMessage(final Header header, final int rcode, final Record question) { final Message response = new Message(); response.setHeader(header); for (int i = 0; i < 4; i++) response.removeAllRecords(i); if (rcode == Rcode.SERVFAIL) response.addRecord(question, Section.QUESTION); header.setRcode(rcode); return response.toWire(); } public byte[] formerrMessage(final byte[] in) { try { return buildErrorMessage(new Header(in), Rcode.FORMERR, null); } catch (final IOException e) { LOG.debug("unable to build error message", e); return null; } } public byte[] errorMessage(final Message query, final int rcode) { return buildErrorMessage(query.getHeader(), rcode, query.getQuestion()); } }