Java tutorial
/************************************************************************* * Copyright 2009-2014 Eucalyptus Systems, Inc. * * This program 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; version 3 of the License. * * This program 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 this program. If not, see http://www.gnu.org/licenses/. * * Please contact Eucalyptus Systems, Inc., 6755 Hollister Ave., Goleta * CA 93117, USA or visit http://www.eucalyptus.com/licenses/ if you need * additional information or have any questions. * * This file may incorporate work covered under the following copyright * and permission notice: * * Software License Agreement (BSD License) * * Copyright (c) 2008, Regents of the University of California * All rights reserved. * * Redistribution and use of this software 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 OWNER 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. USERS OF THIS SOFTWARE ACKNOWLEDGE * THE POSSIBLE PRESENCE OF OTHER OPEN SOURCE LICENSED MATERIAL, * COPYRIGHTED MATERIAL OR PATENTED MATERIAL IN THIS SOFTWARE, * AND IF ANY SUCH MATERIAL IS DISCOVERED THE PARTY DISCOVERING * IT MAY INFORM DR. RICH WOLSKI AT THE UNIVERSITY OF CALIFORNIA, * SANTA BARBARA WHO WILL THEN ASCERTAIN THE MOST APPROPRIATE REMEDY, * WHICH IN THE REGENTS' DISCRETION MAY INCLUDE, WITHOUT LIMITATION, * REPLACEMENT OF THE CODE SO IDENTIFIED, LICENSING OF THE CODE SO * IDENTIFIED, OR WITHDRAWAL OF THE CODE CAPABILITY TO THE EXTENT * NEEDED TO COMPLY WITH ANY SUCH LICENSES OR RIGHTS. ************************************************************************/ package com.eucalyptus.util.dns; import java.lang.reflect.Modifier; import java.net.InetAddress; import java.util.Arrays; import java.util.HashMap; import java.util.List; import java.util.Map; import org.apache.log4j.Logger; import org.xbill.DNS.Flags; import org.xbill.DNS.Message; import org.xbill.DNS.Name; import org.xbill.DNS.RRset; import org.xbill.DNS.Rcode; import org.xbill.DNS.Record; import org.xbill.DNS.SetResponse; import com.eucalyptus.bootstrap.Bootstrap; import com.eucalyptus.bootstrap.ServiceJarDiscovery; import com.eucalyptus.configurable.ConfigurableClass; import com.eucalyptus.configurable.ConfigurableField; import com.google.common.base.Predicate; import com.google.common.base.Supplier; import com.google.common.base.Suppliers; import com.google.common.collect.ClassToInstanceMap; import com.google.common.collect.Collections2; import com.google.common.collect.Iterables; import com.google.common.collect.LinkedHashMultimap; import com.google.common.collect.Multimap; import com.google.common.collect.MutableClassToInstanceMap; @ConfigurableClass(root = "dns", description = "Configuration options controlling the behaviour of DNS features.") public class DnsResolvers extends ServiceJarDiscovery { private static Logger LOG = Logger.getLogger(DnsResolvers.class); @ConfigurableField(description = "Enable pluggable DNS resolvers. " + "Note: This must be 'true' for any pluggable resolver to work. " + "Also, each resolver may need to be separately enabled." + "See 'euca-describe-properties dns'.") public static Boolean enabled = Boolean.TRUE; private static final ClassToInstanceMap<DnsResolver> resolvers = MutableClassToInstanceMap.create(); public enum RequestType implements Predicate<Record> { A(1), NS(2), MD(3), MF(4), CNAME(5), SOA(6), MB(7), MG(8), MR(9), NULL(10), WKS(11), PTR(12), HINFO( 13), MINFO(14), MX(15), TXT(16), RP(17), AFSDB(18), X25(19), ISDN(20), RT(21), NSAP(22), NSAP_PTR( 23), SIG(24), KEY(25), PX(26), GPOS(27), AAAA(28), LOC(29), NXT(30), EID(31), NIMLOC( 32), SRV(33), ATMA(34), NAPTR(35), KX(36), CERT(37), A6(38), DNAME(39), OPT( 41), APL(42), DS(43), SSHFP(44), IPSECKEY(45), RRSIG(46), NSEC(47), DNSKEY( 48), DHCID(49), NSEC3(50), NSEC3PARAM(51), TLSA(52), SPF(99), TKEY( 249), TSIG(250), IXFR(251), AXFR( 252), MAILB(253), MAILA(254), ANY(255), DLV(32769); private static final Supplier<Map<Integer, RequestType>> backingMap = new Supplier() { @Override public Map<Integer, RequestType> get() { return new HashMap() { { for (RequestType t : RequestType.values()) { this.put(t.getType(), t); } } }; } }; private static final Supplier<Map<Integer, RequestType>> typeMap = Suppliers.memoize(backingMap); private final int type; private RequestType(int type) { this.type = type; } @Override public boolean apply(Record input) { return input.getType() == this.type; } public static RequestType typeOf(int type) { if (!typeMap.get().containsKey(type)) { throw new IllegalArgumentException("No RequestType with type=" + type); } else { return typeMap.get().get(type); } } public int getType() { return this.type; } } public enum ResponseSection { QUESTION, ANSWER, AUTHORITY, ADDITIONAL, ZONE { @Override public int section() { return 0; } }, PREREQ { @Override public int section() { return 1; } }, UPDATE { @Override public int section() { return 2; } }; public int section() { return this.ordinal(); } } public enum ResponseType { SUCCESSFUL, CNAME, DELEGATION, DNAME, NXDOMAIN, NXRRSET, UNKNOWN; public static ResponseType lookup(SetResponse sr) { if (sr.isCNAME()) { return CNAME; } else if (sr.isDelegation()) { return DELEGATION; } else if (sr.isDNAME()) { return DNAME; } else if (sr.isNXDOMAIN()) { return NXDOMAIN; } else if (sr.isNXRRSET()) { return NXRRSET; } else if (sr.isSuccessful()) { return SUCCESSFUL; } else { return UNKNOWN; } } } private static RRset createRRset(Record... records) { RRset rrset = new RRset(); for (Record r : records) { rrset.addRR(r); } return rrset; } @SuppressWarnings("unchecked") private static void addRRset(Name name, final Message response, Record[] records, final int section) { final Multimap<RequestType, Record> rrsets = LinkedHashMultimap.create(); for (Record r : records) { RequestType type = RequestType.typeOf(r.getType()); rrsets.get(type).addAll(Collections2.filter(Arrays.asList(records), type)); } Predicate<Record> checkNewRecord = new Predicate<Record>() { @Override public boolean apply(Record input) { for (int s = 1; s <= section; s++) { if (response.findRecord(input, s)) { return false; } } return true; } }; if (rrsets.containsKey(RequestType.CNAME)) { for (Record cnames : Iterables.filter(rrsets.removeAll(RequestType.CNAME), checkNewRecord)) { response.addRecord(cnames, section); } } for (Record sectionRecord : Iterables.filter(rrsets.values(), checkNewRecord)) { response.addRecord(sectionRecord, section); } } public static class DnsResponse { private final Multimap<ResponseSection, Record> sections = LinkedHashMultimap.create(); private final Name name; private boolean recursive = false; private boolean nxdomain = false; public static class Builder { private final DnsResponse response; Builder(Name name) { this.response = new DnsResponse(name); } public Builder withAuthority(List<Record> records) { if (records != null) { this.response.sections.get(ResponseSection.AUTHORITY).addAll(records); } return this; } public Builder withAuthority(Record... records) { if (records != null) { return withAuthority(Arrays.asList(records)); } else { return this; } } public Builder withAdditional(List<Record> records) { if (records != null) { this.response.sections.get(ResponseSection.ADDITIONAL).addAll(records); } return this; } public Builder withAdditional(Record... records) { if (records != null) { return withAdditional(Arrays.asList(records)); } else { return this; } } public Builder recursive() { this.response.recursive = true; return this; } public DnsResponse nxdomain() { this.response.nxdomain = true; return this.response; } public DnsResponse answer(List<? extends Record> records) { if (records != null) { this.response.sections.get(ResponseSection.ANSWER).addAll(records); } return this.response; } public DnsResponse answer(Record... records) { if (records != null) { return answer(Arrays.asList(records)); } else { return this.response; } } } private DnsResponse(Name name) { this.name = name; } public static Builder forName(Name name) { return new Builder(name); } public boolean hasAnswer() { return !this.sections.isEmpty(); } public Record[] section(ResponseSection s) { if (this.sections.containsKey(s)) { return this.sections.get(s).toArray(new Record[] {}); } else { return null; } } public boolean isAuthoritative() { return !this.recursive; } public boolean isNxdomain() { return this.nxdomain; } public boolean isRecursive() { return this.recursive; } } public interface DnsRequest { Record getQuery(); InetAddress getRemoteAddress(); InetAddress getLocalAddress(); } public interface DnsResolver { boolean checkAccepts(DnsRequest request); DnsResponse lookupRecords(DnsRequest request); String toString(); } /** * Returns the list of resolvers which accept the name from the given source address. */ private static Iterable<DnsResolver> resolversFor(final DnsRequest request) { return Iterables.filter(resolvers.values(), new Predicate<DnsResolver>() { @Override public boolean apply(final DnsResolver input) { try { return input.checkAccepts(request); } catch (final Exception ex) { return false; } } }); } private static SetResponse lookupRecords(final Message response, final DnsRequest request) { final Record query = request.getQuery(); final InetAddress source = request.getRemoteAddress(); final Name name = query.getName(); final int type = query.getType(); response.getHeader().setFlag(Flags.RA);// always mark the response w/ the recursion available // bit for (final DnsResolver r : DnsResolvers.resolversFor(request)) { try { final DnsResponse reply = r.lookupRecords(request); if (reply == null) { LOG.debug("DnsResolver: returned null " + name + " using " + r); continue; } if (reply.isAuthoritative()) {// mark response.getHeader().setFlag(Flags.AA); } if (reply.isNxdomain()) { try { addRRset(name, response, new Record[] { DomainNameRecords.sourceOfAuthority(name) }, type); } catch (final Exception ex) { ; } response.getHeader().setRcode(Rcode.NXDOMAIN); return SetResponse.ofType(SetResponse.NXDOMAIN); } else if (reply.hasAnswer()) { for (ResponseSection s : ResponseSection.values()) { Record[] records = reply.section(s); if (records != null) { addRRset(name, response, records, s.section()); } } return SetResponse.ofType(SetResponse.SUCCESSFUL); } } catch (final Exception ex) { LOG.debug("DnsResolver: failed for " + name + " using " + r + " because of: " + ex.getMessage(), ex); } } return SetResponse.ofType(SetResponse.UNKNOWN);// no dice, return unknown } @SuppressWarnings("unchecked") @Override public boolean processClass(final Class candidate) throws Exception { if (DnsResolver.class.isAssignableFrom(candidate) && !Modifier.isAbstract(candidate.getModifiers())) { try { final DnsResolver resolver = (DnsResolver) candidate.newInstance(); resolvers.putInstance(candidate, resolver); return true; } catch (final Exception ex) { LOG.error("Failed to create instance of DnsResolver: " + candidate + " because of: " + ex.getMessage()); } } return false; } @Override public Double getPriority() { return 0.5d; } public static SetResponse findRecords(final Message response, final DnsRequest request) { try { if (!enabled || !Bootstrap.isOperational()) { return SetResponse.ofType(SetResponse.UNKNOWN); } else { final Iterable<DnsResolver> resolverList = DnsResolvers.resolversFor(request); if (Iterables.isEmpty(resolverList)) { return SetResponse.ofType(SetResponse.UNKNOWN); } else { return DnsResolvers.lookupRecords(response, request); } } } catch (final Exception ex) { LOG.error(ex); LOG.trace(ex, ex); } return SetResponse.ofType(SetResponse.UNKNOWN); } }