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Compact DNS client library intended primary for network utilities and testing applications
package com.kendamasoft.dns;
import com.kendamasoft.dns.records.*;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
/**
* DNS Protocol data structures
*
* DNS Message in both way consists of {@link Header}, {@link QuestionEntry}
* and zero or any number of {@link DnsProtocol.ResourceRecord}
*
*
* https://www.ietf.org/rfc/rfc1035.txt
* https://technet.microsoft.com/en-us/library/dd197470(v=ws.10).aspx
* https://en.wikipedia.org/wiki/List_of_DNS_record_types
*/
public class DnsProtocol {
static public final int MAX_MESSAGE_LENGTH = 512;
static public final short QUESTION_CLASS_IN = 0x0001;
/**
* Resource Records types with {@link RecordType#getId() codes} and {@link RecordType#getDescription() desciprtion}.
*
* Full list:
* https://en.wikipedia.org/wiki/List_of_DNS_record_types
*
* Fully supported only commonly used record types:
* {@link AAAARecord}
* {@link ARecord}
* {@link MXRecord}
* {@link NSRecord}
* {@link TXTRecord}
* {@link SOARecord}
*/
public enum RecordType {
/*********************************
* Supported Record Types *
*********************************/
/**
* IPv4 host address
*/
A ((short)1, ARecord.class, "IPv4 host address"),
/**
* Name server
*/
NS ((short)2, NSRecord.class, "Name server"),
/**
* Start of [a zone of] authority record
*/
SOA ((short)6, SOARecord.class, "Start of [a zone of] authority record"),
/**
* Pointer to a canonical name
*/
PTR ((short)12, PTRRecord.class, "Pointer to a canonical name"),
/**
* Mail exchange
*/
MX ((short)15, MXRecord.class, "Mail exchange"),
/**
* Text record
*/
TXT ((short)16, TXTRecord.class, "Text record"),
/**
* IPv6 host address
*/
AAAA ((short)28, AAAARecord.class,"IPv6 host address"),
/*********************************
* Not supported, but known types *
**********************************/
/**
* Canonical name record
*/
CNAME ((short)5, UnknownRecord.class, "Canonical name record"),
/**
* Host information
*/
HINFO ((short)13, UnknownRecord.class, "Host information"),
/**
* Responsible person
*/
RP ((short)17, UnknownRecord.class, "Responsible person"),
/**
* AFS database record
*/
AFSDB ((short)18, UnknownRecord.class, "AFS database record"),
/**
* Signature
*/
SIG ((short)24, UnknownRecord.class, "Signature"),
/**
* Location record
*/
LOC ((short)29, UnknownRecord.class, "Location record"),
/**
* Service locator
*/
SRV ((short)33, UnknownRecord.class, "Service locator"),
/**
* Naming Authority Pointer
*/
NAPTR ((short)35, UnknownRecord.class, "Naming Authority Pointer"),
/**
* Key eXchanger record
*/
KX ((short)36, UnknownRecord.class, "Key eXchanger record"),
/**
* Certificate record
*/
CERT ((short)37, UnknownRecord.class, "Certificate record"),
/**
* Delegation Name
*/
DNAME ((short)39, UnknownRecord.class, "Delegation Name"),
/**
* Address Prefix List
*/
APL ((short)42, UnknownRecord.class, "Address Prefix List"),
/**
* Delegation signer
*/
DS ((short)43, UnknownRecord.class, "Delegation signer"),
/**
* SSH Public Key Fingerprint
*/
SSHFP ((short)44, UnknownRecord.class, "SSH Public Key Fingerprint"),
/**
* IPsec Key
*/
IPSECKEY ((short)45, UnknownRecord.class, "IPsec Key"),
/**
* DNSSEC signature
*/
RRSIG ((short)46, UnknownRecord.class, "DNSSEC signature"),
/**
* Next-Secure record
*/
NSEC ((short)47, UnknownRecord.class, "Next-Secure record"),
/**
* DNS Key record
*/
DNSKEY((short)48, UnknownRecord.class, "DNS Key record"),
/**
* DHCP identifier
*/
DHCID((short)49, UnknownRecord.class, "DHCP identifier"),
/**
* NSEC record version 3
*/
NSEC3((short)50, UnknownRecord.class, "NSEC record version 3"),
/**
* NSEC3 parameters
*/
NSEC3PARAM((short)51, UnknownRecord.class, "NSEC3 parameters"),
/**
* TLSA certificate association
*/
TLSA((short)52, UnknownRecord.class, "TLSA certificate association"),
/**
* Host Identity Protocol
*/
HIP((short)55, UnknownRecord.class, "Host Identity Protocol"),
/**
* Child DS
*/
CDS((short)59, UnknownRecord.class, "Child DS"),
/**
* Child DNSKEY
*/
CDNSKEY((short)60, UnknownRecord.class, "Child DNSKEY"),
/**
* Secret key record
*/
TKEY((short)249, UnknownRecord.class, "Secret key record"),
/**
* Transaction Signature
*/
TSIG((short)250, UnknownRecord.class, "Transaction Signature"),
/**
* Obsolete: Sender Policy Framework
*/
SPF ((short)99, SPFRecord.class, "Obsolete: Sender Policy Framework"),
/**
* Certification Authority Authorization
*/
CAA ((short)257, CAARecord.class, "Certification Authority Authorization"),
/**
* Type to request all known resource records for given domain name.
*/
ANY ((short)255, UnknownRecord.class, "All cached records");
private final short id;
private final Class recordClass;
private final String description;
RecordType(short id, Class recordClass, String description) {
this.id = id;
this.recordClass = recordClass;
this.description = description;
}
/**
* @return code of record type
*/
public short getId() {
return id;
}
/**
* @return simple description of the type
*/
public String getDescription() {
return description;
}
static public RecordType getById(short id) {
for(RecordType type : values()) {
if(type.id == id) {
return type;
}
}
return null;
}
}
/**
* DNS Message Header
*
* 2 octet transaction Id
* 2 octet flags
* 2 octet question resource count
* 2 octet answer resource count
* 2 octet authority resource count
* 2 octet additional resource count
*
* @see Header#flags
*/
public static class Header {
/**
* 0 - request, 1 - response
*/
static public final int FLAG_MESSAGE_TYPE = (1 << 15);
static public final int FLAG_AUTHORITATIVE_RESPONSE = (1 << 10);
/**
* 1 - data truncation, should switch connection from UDP to TCP
*/
static public final int FLAG_TRUNCATION = (1 << 9);
static public final int FLAG_RECURSION_DESIRED = (1 << 8);
static public final int FLAG_RECURSION_AVAILABLE = (1 << 7);
short transactionId;
/**
* Flags bit layout (from most significant bit to less)
*
* first octet
* [0] - req [=0] / res [=1]
* [1,4] - op code ([=0] for query)
* [5] - authoritative response [=1]
* [6] - truncation (if [=1] - exceeded limit in 512b)
* [7] - recursion desired [=1]
* second octet
* [0] - recursion available
* [1-3] - reserved
* [4-7] - return code ([=0] success, [=0x3] error)
*
*/
short flags;
short questionResourceRecordCount;
short answerResourceRecordsCount;
short authorityResourceRecordsCount;
short additionalResourceRecordsCount;
public short getAnswerResourceRecordsCount() {
return answerResourceRecordsCount;
}
public short getAuthorityResourceRecordsCount() {
return authorityResourceRecordsCount;
}
public short getAdditionalResourceRecordsCount() {
return additionalResourceRecordsCount;
}
/**
* @see Header#FLAG_MESSAGE_TYPE
* @see Header#FLAG_AUTHORITATIVE_RESPONSE
* @see Header#FLAG_TRUNCATION
* @see Header#FLAG_RECURSION_DESIRED
* @see Header#FLAG_RECURSION_AVAILABLE
* @param flag to check
* @return is flag set
*/
public boolean hasFlag(int flag) {
return ((flags & 0xffff) & flag) > 0;
}
/**
* @return operation code (zero for query)
*/
public int opCode() {
// 0b0111_0000_0000_0000;
return flags & 0x7000;
}
/**
* @return return code (zero - success, 0x3 - error)
*/
public int returnCode() {
// 0b0000_0111
return flags & 0xf;
}
}
/**
* DNS resource question query.
* Not directly usable.
*/
static class QuestionEntry {
/**
* Resource name (typically domain name we want to query)
*/
String name;
/**
* Record type we want to know
* @see RecordType
*/
short type;
/**
* @see DnsProtocol#QUESTION_CLASS_IN
*/
short questionClass;
}
/**
* DNS protocol message model
*/
public static class Message {
Header header;
QuestionEntry questionEntry;
List answerRecordList;
List authorityRecordList;
List additionalRecordList;
public Header getHeader() {
return header;
}
/**
* @return answer section resource records
*/
public List getAnswerRecordList() {
if(answerRecordList == null)
//noinspection unchecked
return Collections.EMPTY_LIST;
return Collections.unmodifiableList(answerRecordList);
}
/**
* @return authority section resource records
*/
public List getAuthorityRecordList() {
if(authorityRecordList == null)
//noinspection unchecked
return Collections.EMPTY_LIST;
return Collections.unmodifiableList(authorityRecordList);
}
/**
* @return additional section resource records
*/
public List getAdditionalRecordList() {
if(additionalRecordList == null)
//noinspection unchecked
return Collections.EMPTY_LIST;
return Collections.unmodifiableList(additionalRecordList);
}
/**
* Get all returned Resource Records sorted by type.
* If there are no records will return empty list.
* @return all resource records
* @see Message#getAnswerRecordList()
* @see Message#getAuthorityRecordList()
* @see Message#getAdditionalRecordList()
*/
public List getAllRecords() {
List result = new ArrayList();
if(answerRecordList != null) {
result.addAll(answerRecordList);
}
if(authorityRecordList != null) {
result.addAll(authorityRecordList);
}
if(additionalRecordList != null) {
result.addAll(additionalRecordList);
}
Collections.sort(result, new Comparator() {
@Override
public int compare(ResourceRecord o1, ResourceRecord o2) {
return o1.recordTypeId - o2.recordTypeId;
}
});
return result;
}
}
/**
* Resource Record
*/
public static class ResourceRecord {
/**
* Record name
*/
String name;
/**
* @see RecordType
*/
RecordType recordType;
short recordTypeId;
/**
* @see QuestionEntry#questionClass
*/
short recordClass;
/**
* ttl
* unsigned 32-bit int
*/
long ttl;
short dataLength;
Record content;
/**
* @return record name
*/
public String getName() {
return name;
}
/**
* @return record TTL
*/
public long getTtl() {
return ttl;
}
/**
* @see RecordType
* @return record type
*/
public RecordType getRecordType() {
return recordType;
}
/**
* @see AAAARecord
* @see ARecord
* @see CAARecord
* @see MXRecord
* @see NSRecord
* @see PTRRecord
* @see SOARecord
* @see SPFRecord
* @see TXTRecord
*
* @return actual content of this record
*/
public Record getContent() {
return content;
}
void readRecord(Buffer buffer) {
if(recordType == null) {
content = new UnknownRecord(null, recordTypeId);
} else {
try {
content = recordType.recordClass.newInstance();
} catch (Exception ex) {
content = new UnknownRecord(recordType, recordTypeId);
}
}
content.parseData(dataLength, buffer);
}
/**
* @return string representation of record in form "domain.name. 6666 IN A 1.2.3.4"
*/
@Override
public String toString() {
return name + " " + ttl + " IN " + content;
}
}
}
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