001/* 002 * Copyright 2015-2020 the original author or authors 003 * 004 * This software is licensed under the Apache License, Version 2.0, 005 * the GNU Lesser General Public License version 2 or later ("LGPL") 006 * and the WTFPL. 007 * You may choose either license to govern your use of this software only 008 * upon the condition that you accept all of the terms of either 009 * the Apache License 2.0, the LGPL 2.1+ or the WTFPL. 010 */ 011package org.minidns.cache; 012 013import java.util.HashMap; 014import java.util.LinkedList; 015import java.util.List; 016import java.util.Map; 017import java.util.Map.Entry; 018 019import org.minidns.dnsmessage.DnsMessage; 020import org.minidns.dnsmessage.Question; 021import org.minidns.dnsname.DnsName; 022import org.minidns.dnsqueryresult.CachedDnsQueryResult; 023import org.minidns.dnsqueryresult.DnsQueryResult; 024import org.minidns.dnsqueryresult.SynthesizedCachedDnsQueryResult; 025import org.minidns.record.Data; 026import org.minidns.record.Record; 027 028/** 029 * A variant of {@link LruCache} also using the data found in the sections for caching. 030 */ 031public class ExtendedLruCache extends LruCache { 032 033 public ExtendedLruCache() { 034 this(DEFAULT_CACHE_SIZE); 035 } 036 037 public ExtendedLruCache(int capacity) { 038 super(capacity); 039 } 040 041 public ExtendedLruCache(int capacity, long maxTTL) { 042 super(capacity, maxTTL); 043 } 044 045 @SuppressWarnings("UnsynchronizedOverridesSynchronized") 046 @Override 047 protected void putNormalized(DnsMessage q, DnsQueryResult result) { 048 super.putNormalized(q, result); 049 DnsMessage message = result.response; 050 Map<DnsMessage, List<Record<? extends Data>>> extraCaches = new HashMap<>(message.additionalSection.size()); 051 052 gather(extraCaches, q, message.answerSection, null); 053 gather(extraCaches, q, message.authoritySection, null); 054 gather(extraCaches, q, message.additionalSection, null); 055 056 putExtraCaches(result, extraCaches); 057 } 058 059 @Override 060 public void offer(DnsMessage query, DnsQueryResult result, DnsName authoritativeZone) { 061 DnsMessage reply = result.response; 062 // The reply shouldn't be an authoritative answers when offer() is used. That would be a case for put(). 063 assert !reply.authoritativeAnswer; 064 065 Map<DnsMessage, List<Record<? extends Data>>> extraCaches = new HashMap<>(reply.additionalSection.size()); 066 067 // N.B. not gathering from reply.answerSection here. Since it is a non authoritativeAnswer it shouldn't contain anything. 068 gather(extraCaches, query, reply.authoritySection, authoritativeZone); 069 gather(extraCaches, query, reply.additionalSection, authoritativeZone); 070 071 putExtraCaches(result, extraCaches); 072 } 073 074 private void gather(Map<DnsMessage, List<Record<?extends Data>>> extraCaches, DnsMessage q, List<Record<? extends Data>> records, DnsName authoritativeZone) { 075 for (Record<? extends Data> extraRecord : records) { 076 if (!shouldGather(extraRecord, q.getQuestion(), authoritativeZone)) 077 continue; 078 079 DnsMessage.Builder additionalRecordQuestionBuilder = extraRecord.getQuestionMessage(); 080 if (additionalRecordQuestionBuilder == null) 081 continue; 082 083 additionalRecordQuestionBuilder.copyFlagsFrom(q); 084 085 additionalRecordQuestionBuilder.setAdditionalResourceRecords(q.additionalSection); 086 087 DnsMessage additionalRecordQuestion = additionalRecordQuestionBuilder.build(); 088 if (additionalRecordQuestion.equals(q)) { 089 // No need to cache the additional question if it is the same as the original question. 090 continue; 091 } 092 093 List<Record<? extends Data>> additionalRecords = extraCaches.get(additionalRecordQuestion); 094 if (additionalRecords == null) { 095 additionalRecords = new LinkedList<>(); 096 extraCaches.put(additionalRecordQuestion, additionalRecords); 097 } 098 additionalRecords.add(extraRecord); 099 } 100 } 101 102 private void putExtraCaches(DnsQueryResult synthesynthesizationSource, Map<DnsMessage, List<Record<? extends Data>>> extraCaches) { 103 DnsMessage reply = synthesynthesizationSource.response; 104 for (Entry<DnsMessage, List<Record<? extends Data>>> entry : extraCaches.entrySet()) { 105 DnsMessage question = entry.getKey(); 106 DnsMessage answer = reply.asBuilder() 107 .setQuestion(question.getQuestion()) 108 .setAuthoritativeAnswer(true) 109 .addAnswers(entry.getValue()) 110 .build(); 111 CachedDnsQueryResult cachedDnsQueryResult = new SynthesizedCachedDnsQueryResult(question, answer, synthesynthesizationSource); 112 synchronized (this) { 113 backend.put(question, cachedDnsQueryResult); 114 } 115 } 116 } 117 118 protected boolean shouldGather(Record<? extends Data> extraRecord, Question question, DnsName authoritativeZone) { 119 boolean extraRecordIsChildOfQuestion = extraRecord.name.isChildOf(question.name); 120 121 boolean extraRecordIsChildOfAuthoritativeZone = false; 122 if (authoritativeZone != null) { 123 extraRecordIsChildOfAuthoritativeZone = extraRecord.name.isChildOf(authoritativeZone); 124 } 125 126 return extraRecordIsChildOfQuestion || extraRecordIsChildOfAuthoritativeZone; 127 } 128 129}