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.edns; 012 013import java.util.ArrayList; 014import java.util.Collections; 015import java.util.HashMap; 016import java.util.Iterator; 017import java.util.List; 018import java.util.Map; 019 020import org.minidns.dnsname.DnsName; 021import org.minidns.record.Data; 022import org.minidns.record.OPT; 023import org.minidns.record.Record; 024import org.minidns.record.Record.TYPE; 025 026/** 027 * EDNS - Extension Mechanism for DNS. 028 * 029 * @see <a href="https://tools.ietf.org/html/rfc6891">RFC 6891 - Extension Mechanisms for DNS (EDNS(0))</a> 030 * 031 */ 032public class Edns { 033 034 /** 035 * Inform the dns server that the client supports DNSSEC. 036 */ 037 public static final int FLAG_DNSSEC_OK = 0x8000; 038 039 /** 040 * The EDNS option code. 041 * 042 * @see <a href="http://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-11">IANA - DNS EDNS0 Option Codes (OPT)</a> 043 */ 044 public enum OptionCode { 045 UNKNOWN(-1, UnknownEdnsOption.class), 046 NSID(3, Nsid.class), 047 ; 048 049 private static Map<Integer, OptionCode> INVERSE_LUT = new HashMap<>(OptionCode.values().length); 050 051 static { 052 for (OptionCode optionCode : OptionCode.values()) { 053 INVERSE_LUT.put(optionCode.asInt, optionCode); 054 } 055 } 056 057 public final int asInt; 058 public final Class<? extends EdnsOption> clazz; 059 060 OptionCode(int optionCode, Class<? extends EdnsOption> clazz) { 061 this.asInt = optionCode; 062 this.clazz = clazz; 063 } 064 065 public static OptionCode from(int optionCode) { 066 OptionCode res = INVERSE_LUT.get(optionCode); 067 if (res == null) res = OptionCode.UNKNOWN; 068 return res; 069 } 070 } 071 072 public final int udpPayloadSize; 073 074 /** 075 * 8-bit extended return code. 076 * 077 * RFC 6891 § 6.1.3 EXTENDED-RCODE 078 */ 079 public final int extendedRcode; 080 081 /** 082 * 8-bit version field. 083 * 084 * RFC 6891 § 6.1.3 VERSION 085 */ 086 public final int version; 087 088 /** 089 * 16-bit flags. 090 * 091 * RFC 6891 § 6.1.4 092 */ 093 public final int flags; 094 095 public final List<EdnsOption> variablePart; 096 097 public final boolean dnssecOk; 098 099 private Record<OPT> optRecord; 100 101 public Edns(Record<OPT> optRecord) { 102 assert optRecord.type == TYPE.OPT; 103 udpPayloadSize = optRecord.clazzValue; 104 extendedRcode = (int) ((optRecord.ttl >> 8) & 0xff); 105 version = (int) ((optRecord.ttl >> 16) & 0xff); 106 flags = (int) optRecord.ttl & 0xffff; 107 108 dnssecOk = (optRecord.ttl & FLAG_DNSSEC_OK) > 0; 109 110 OPT opt = optRecord.payloadData; 111 variablePart = opt.variablePart; 112 this.optRecord = optRecord; 113 } 114 115 public Edns(Builder builder) { 116 udpPayloadSize = builder.udpPayloadSize; 117 extendedRcode = builder.extendedRcode; 118 version = builder.version; 119 int flags = 0; 120 if (builder.dnssecOk) { 121 flags |= FLAG_DNSSEC_OK; 122 } 123 dnssecOk = builder.dnssecOk; 124 this.flags = flags; 125 if (builder.variablePart != null) { 126 variablePart = builder.variablePart; 127 } else { 128 variablePart = Collections.emptyList(); 129 } 130 } 131 132 @SuppressWarnings("unchecked") 133 public <O extends EdnsOption> O getEdnsOption(OptionCode optionCode) { 134 for (EdnsOption o : variablePart) { 135 if (o.getOptionCode().equals(optionCode)) { 136 return (O) o; 137 } 138 } 139 return null; 140 } 141 142 public Record<OPT> asRecord() { 143 if (optRecord == null) { 144 long optFlags = flags; 145 optFlags |= extendedRcode << 8; 146 optFlags |= version << 16; 147 optRecord = new Record<OPT>(DnsName.ROOT, Record.TYPE.OPT, udpPayloadSize, optFlags, new OPT(variablePart)); 148 } 149 return optRecord; 150 } 151 152 private String terminalOutputCache; 153 154 public String asTerminalOutput() { 155 if (terminalOutputCache == null) { 156 StringBuilder sb = new StringBuilder(); 157 sb.append("EDNS: version: ").append(version).append(", flags:"); 158 if (dnssecOk) 159 sb.append(" do"); 160 sb.append("; udp: ").append(udpPayloadSize); 161 if (!variablePart.isEmpty()) { 162 sb.append('\n'); 163 Iterator<EdnsOption> it = variablePart.iterator(); 164 while (it.hasNext()) { 165 EdnsOption edns = it.next(); 166 sb.append(edns.getOptionCode()).append(": "); 167 sb.append(edns.asTerminalOutput()); 168 if (it.hasNext()) { 169 sb.append('\n'); 170 } 171 } 172 } 173 terminalOutputCache = sb.toString(); 174 } 175 return terminalOutputCache; 176 } 177 178 @Override 179 public String toString() { 180 return asTerminalOutput(); 181 } 182 183 public static Edns fromRecord(Record<? extends Data> record) { 184 if (record.type != TYPE.OPT) return null; 185 186 @SuppressWarnings("unchecked") 187 Record<OPT> optRecord = (Record<OPT>) record; 188 return new Edns(optRecord); 189 } 190 191 public static Builder builder() { 192 return new Builder(); 193 } 194 195 public static final class Builder { 196 private int udpPayloadSize; 197 private int extendedRcode; 198 private int version; 199 private boolean dnssecOk; 200 private List<EdnsOption> variablePart; 201 202 private Builder() { 203 } 204 205 public Builder setUdpPayloadSize(int udpPayloadSize) { 206 if (udpPayloadSize > 0xffff) { 207 throw new IllegalArgumentException("UDP payload size must not be greater than 65536, was " + udpPayloadSize); 208 } 209 this.udpPayloadSize = udpPayloadSize; 210 return this; 211 } 212 213 public Builder setDnssecOk(boolean dnssecOk) { 214 this.dnssecOk = dnssecOk; 215 return this; 216 } 217 218 public Builder setDnssecOk() { 219 dnssecOk = true; 220 return this; 221 } 222 223 public Builder addEdnsOption(EdnsOption ednsOption) { 224 if (variablePart == null) { 225 variablePart = new ArrayList<>(4); 226 } 227 variablePart.add(ednsOption); 228 return this; 229 } 230 231 public Edns build() { 232 return new Edns(this); 233 } 234 } 235}