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Minimal DNS library for java and android systems
/*
* Copyright 2015-2016 the original author or authors
*
* This software is licensed under the Apache License, Version 2.0,
* the GNU Lesser General Public License version 2 or later ("LGPL")
* and the WTFPL.
* You may choose either license to govern your use of this software only
* upon the condition that you accept all of the terms of either
* the Apache License 2.0, the LGPL 2.1+ or the WTFPL.
*/
package de.measite.minidns;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import de.measite.minidns.Record.TYPE;
import de.measite.minidns.edns.EDNSOption;
import de.measite.minidns.edns.NSID;
import de.measite.minidns.edns.UnknownEDNSOption;
import de.measite.minidns.record.Data;
import de.measite.minidns.record.OPT;
/**
* EDNS - Extension Mechanism for DNS.
*
* @see RFC 6891 - Extension Mechanisms for DNS (EDNS(0))
*
*/
public class EDNS {
/**
* Inform the dns server that the client supports DNSSEC.
*/
public static final int FLAG_DNSSEC_OK = 0x8000;
/**
* The EDNS option code.
*
* @see IANA - DNS EDNS0 Option Codes (OPT)
*/
public enum OptionCode {
UNKNOWN(-1, UnknownEDNSOption.class),
NSID(3, NSID.class),
;
private static Map INVERSE_LUT = new HashMap<>(OptionCode.values().length);
static {
for (OptionCode optionCode: OptionCode.values()) {
INVERSE_LUT.put(optionCode.asInt, optionCode);
}
}
public final int asInt;
public final Class clazz;
OptionCode(int optionCode, Class clazz) {
this.asInt = optionCode;
this.clazz = clazz;
}
public static OptionCode from(int optionCode) {
OptionCode res = INVERSE_LUT.get(optionCode);
if (res == null) res = OptionCode.UNKNOWN;
return res;
}
}
public final int udpPayloadSize;
/**
* 8-bit extended return code.
*
* RFC 6891 § 6.1.3 EXTENDED-RCODE
*/
public final int extendedRcode;
/**
* 8-bit version field.
*
* RFC 6891 § 6.1.3 VERSION
*/
public final int version;
/**
* 16-bit flags.
*
* RFC 6891 § 6.1.4
*/
public final int flags;
public final List variablePart;
public final boolean dnssecOk;
private Record optRecord;
public EDNS(Record optRecord) {
assert (optRecord.type == TYPE.OPT);
udpPayloadSize = optRecord.clazzValue;
extendedRcode = (int) ((optRecord.ttl >> 8) & 0xff);
version = (int) ((optRecord.ttl >> 16) & 0xff);
flags = (int) optRecord.ttl & 0xffff;
dnssecOk = (optRecord.ttl & FLAG_DNSSEC_OK) > 0;
OPT opt = optRecord.payloadData;
variablePart = opt.variablePart;
this.optRecord = optRecord;
}
public EDNS(Builder builder) {
udpPayloadSize = builder.udpPayloadSize;
extendedRcode = builder.extendedRcode;
version = builder.version;
int flags = 0;
if (builder.dnssecOk) {
flags |= FLAG_DNSSEC_OK;
}
dnssecOk = builder.dnssecOk;
this.flags = flags;
if (builder.variablePart != null) {
variablePart = builder.variablePart;
} else {
variablePart = Collections.emptyList();
}
}
@SuppressWarnings("unchecked")
public O getEdnsOption(OptionCode optionCode) {
for (EDNSOption o : variablePart) {
if (o.getOptionCode().equals(optionCode)) {
return (O) o;
}
}
return null;
}
public Record asRecord() {
if (optRecord == null) {
long optFlags = flags;
optFlags |= (extendedRcode << 8);
optFlags |= (version << 16);
optRecord = new Record(DNSName.EMPTY, Record.TYPE.OPT, udpPayloadSize, optFlags, new OPT(variablePart));
}
return optRecord;
}
private String terminalOutputCache;
public String asTerminalOutput() {
if (terminalOutputCache == null) {
StringBuilder sb = new StringBuilder();
sb.append("EDNS: version: ").append(version).append(", flags:");
if (dnssecOk)
sb.append(" do");
sb.append("; udp: ").append(udpPayloadSize);
if (!variablePart.isEmpty()) {
sb.append('\n');
Iterator it = variablePart.iterator();
while (it.hasNext()) {
EDNSOption edns = it.next();
sb.append(edns.getOptionCode()).append(": ");
sb.append(edns.asTerminalOutput());
if (it.hasNext()) {
sb.append('\n');
}
}
}
terminalOutputCache = sb.toString();
}
return terminalOutputCache;
}
@Override
public String toString() {
return asTerminalOutput();
}
public static EDNS fromRecord(Record record) {
if (record.type != TYPE.OPT) return null;
@SuppressWarnings("unchecked")
Record optRecord = (Record) record;
return new EDNS(optRecord);
}
public static Builder builder() {
return new Builder();
}
public static class Builder {
private int udpPayloadSize;
private int extendedRcode;
private int version;
private boolean dnssecOk;
private List variablePart;
private Builder() {
}
public Builder setUdpPayloadSize(int udpPayloadSize) {
if (udpPayloadSize > 0xffff) {
throw new IllegalArgumentException("UDP payload size must not be greater than 65536, was " + udpPayloadSize);
}
this.udpPayloadSize = udpPayloadSize;
return this;
}
public Builder setDnssecOk(boolean dnssecOk) {
this.dnssecOk = dnssecOk;
return this;
}
public Builder setDnssecOk() {
dnssecOk = true;
return this;
}
public Builder addEdnsOption(EDNSOption ednsOption) {
if (variablePart == null) {
variablePart = new ArrayList<>(4);
}
variablePart.add(ednsOption);
return this;
}
public EDNS build() {
return new EDNS(this);
}
}
}