package de.measite.minidns; import java.io.DataInputStream; import java.io.IOException; import java.util.HashMap; import de.measite.minidns.record.A; import de.measite.minidns.record.AAAA; import de.measite.minidns.record.CNAME; import de.measite.minidns.record.Data; import de.measite.minidns.record.NS; import de.measite.minidns.record.SRV; import de.measite.minidns.util.NameUtil; /** * A generic DNS record. */ public class Record { /** * The record type. * {@see http://www.iana.org/assignments/dns-parameters} */ public static enum TYPE { 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), SINK(40), OPT(41), APL(42), DS(43), SSHFP(44), IPSECKEY(45), RRSIG(46), NSEC(47), DNSKEY(48), DHCID(49), NSEC3(50), NSEC3PARAM(51), HIP(55), NINFO(56), RKEY(57), TALINK(58), SPF(99), UINFO(100), UID(101), GID(102), TKEY(249), TSIG(250), IXFR(251), AXFR(252), MAILB(253), MAILA(254), ANY(255), TA(32768), DLV(32769); /** * The value of this DNS record type. */ private final int value; /** * Internal lookup table to map values to types. */ private final static HashMap INVERSE_LUT = new HashMap(); /** * Initialize the reverse lookup table. */ static { for(TYPE t: TYPE.values()) { INVERSE_LUT.put(t.getValue(), t); } } /** * Create a new record type. * @param value The binary value of this type. */ private TYPE(int value) { this.value = value; } /** * Retrieve the binary value of this type. * @return The binary value. */ public int getValue() { return value; } /** * Retrieve the symbolic type of the binary value. * @param value The binary type value. * @return The symbolic tpye. */ public static TYPE getType(int value) { return INVERSE_LUT.get(value); } }; /** * The symbolic class of a DNS record (usually IN for Internet). */ public static enum CLASS { IN(1), CH(3), HS(4), NONE(254), ANY(255); /** * Internal reverse lookup table to map binary class values to symbolic * names. */ private final static HashMap INVERSE_LUT = new HashMap(); /** * Initialize the interal reverse lookup table. */ static { for(CLASS c: CLASS.values()) { INVERSE_LUT.put(c.getValue(), c); } } /** * The binary value of this dns class. */ private final int value; /** * Create a new DNS class based on a binary value. * @param value The binary value of this DNS class. */ private CLASS(int value) { this.value = value; } /** * Retrieve the binary value of this DNS class. * @return The binary value of this DNS class. */ public int getValue() { return value; } /** * Retrieve the symbolic DNS class for a binary class value. * @param value The binary DNS class value. * @return The symbolic class instance. */ public static CLASS getClass(int value) { return INVERSE_LUT.get(value); } } /** * The generic name of this record. */ protected String name; /** * The type (and payload type) of this record. */ protected TYPE type; /** * The record class (usually CLASS.IN). */ protected CLASS clazz; /** * The ttl of this record. */ protected long ttl; /** * The payload object of this record. */ protected Data payloadData; /** * Parse a given record based on the full message data and the current * stream position. * @param dis The DataInputStream positioned at the first record byte. * @param data The full message data. * @throws IOException In case of malformed replies. */ public void parse(DataInputStream dis, byte[] data) throws IOException { this.name = NameUtil.parse(dis, data); this.type = TYPE.getType(dis.readUnsignedShort()); this.clazz = CLASS.getClass(dis.readUnsignedShort()); this.ttl = (((long)dis.readUnsignedShort()) << 32) + dis.readUnsignedShort(); int payloadLength = dis.readUnsignedShort(); switch (this.type) { case SRV: this.payloadData = new SRV(); break; case AAAA: this.payloadData = new AAAA(); break; case A: this.payloadData = new A(); break; case NS: this.payloadData = new NS(); break; case CNAME: this.payloadData = new CNAME(); break; default: System.out.println("Unparsed type " + type); this.payloadData = null; for (int i = 0; i < payloadLength; i++) { dis.readByte(); } break; } if (this.payloadData != null) { this.payloadData.parse(dis, data, payloadLength); } } /** * Retrieve a textual representation of this resource record. * @return String */ @Override public String toString() { if (payloadData == null) { return "RR " + type + "/" + clazz; } return "RR " + type + "/" + clazz + ": " + payloadData.toString(); }; /** * Check if this record answers a given query. * @param q The query. * @return True if this record is a valid answer. */ public boolean isAnswer(Question q) { return ((q.getType() == type) || (q.getType() == TYPE.ANY)) && ((q.getClazz() == clazz) || (q.getClazz() == CLASS.ANY)) && (q.getName().equals(name)); } public String getName() { return name; } public Data getPayload() { return payloadData; } }