Java example source code file (ResourceRecord.java)
The ResourceRecord.java Java example source code/*
* Copyright (c) 2000, 2002, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.sun.jndi.dns;
import javax.naming.InvalidNameException;
/**
* The ResourceRecord class represents a DNS resource record.
* The string format is based on the master file representation in
* RFC 1035.
*
* @author Scott Seligman
*/
public class ResourceRecord {
/*
* Resource record type codes
*/
static final int TYPE_A = 1;
static final int TYPE_NS = 2;
static final int TYPE_CNAME = 5;
static final int TYPE_SOA = 6;
static final int TYPE_PTR = 12;
static final int TYPE_HINFO = 13;
static final int TYPE_MX = 15;
static final int TYPE_TXT = 16;
static final int TYPE_AAAA = 28;
static final int TYPE_SRV = 33;
static final int TYPE_NAPTR = 35;
static final int QTYPE_AXFR = 252; // zone transfer
static final int QTYPE_STAR = 255; // query type "*"
/*
* Mapping from resource record type codes to type name strings.
*/
static final String rrTypeNames[] = {
null, "A", "NS", null, null,
"CNAME", "SOA", null, null, null,
null, null, "PTR", "HINFO", null,
"MX", "TXT", null, null, null,
null, null, null, null, null,
null, null, null, "AAAA", null,
null, null, null, "SRV", null,
"NAPTR"
};
/*
* Resource record class codes
*/
static final int CLASS_INTERNET = 1;
static final int CLASS_HESIOD = 2;
static final int QCLASS_STAR = 255; // query class "*"
/*
* Mapping from resource record type codes to class name strings.
*/
static final String rrClassNames[] = {
null, "IN", null, null, "HS"
};
byte[] msg; // DNS message
int msgLen; // msg size (in octets)
boolean qSection; // true if this RR is part of question section
// and therefore has no ttl or rdata
int offset; // offset of RR w/in msg
int rrlen; // number of octets in encoded RR
DnsName name; // name field of RR, including root label
int rrtype; // type field of RR
String rrtypeName; // name of of rrtype
int rrclass; // class field of RR
String rrclassName; // name of rrclass
int ttl = 0; // ttl field of RR
int rdlen = 0; // number of octets of rdata
Object rdata = null; // rdata -- most are String, unknown are byte[]
/*
* Constructs a new ResourceRecord. The encoded data of the DNS
* message is contained in msg; data for this RR begins at msg[offset].
* If qSection is true this RR is part of a question section. It's
* not a true resource record in that case, but is treated as if it
* were a shortened one (with no ttl or rdata). If decodeRdata is
* false, the rdata is not decoded (and getRdata() will return null)
* unless this is an SOA record.
*
* @throws InvalidNameException if a decoded domain name isn't valid.
* @throws ArrayIndexOutOfBoundsException given certain other corrupt data.
*/
ResourceRecord(byte[] msg, int msgLen, int offset,
boolean qSection, boolean decodeRdata)
throws InvalidNameException {
this.msg = msg;
this.msgLen = msgLen;
this.offset = offset;
this.qSection = qSection;
decode(decodeRdata);
}
public String toString() {
String text = name + " " + rrclassName + " " + rrtypeName;
if (!qSection) {
text += " " + ttl + " " +
((rdata != null) ? rdata : "[n/a]");
}
return text;
}
/*
* Returns the name field of this RR, including the root label.
*/
public DnsName getName() {
return name;
}
/*
* Returns the number of octets in the encoded RR.
*/
public int size() {
return rrlen;
}
public int getType() {
return rrtype;
}
public int getRrclass() {
return rrclass;
}
public Object getRdata() {
return rdata;
}
public static String getTypeName(int rrtype) {
return valueToName(rrtype, rrTypeNames);
}
public static int getType(String typeName) {
return nameToValue(typeName, rrTypeNames);
}
public static String getRrclassName(int rrclass) {
return valueToName(rrclass, rrClassNames);
}
public static int getRrclass(String className) {
return nameToValue(className, rrClassNames);
}
private static String valueToName(int val, String[] names) {
String name = null;
if ((val > 0) && (val < names.length)) {
name = names[val];
} else if (val == QTYPE_STAR) { // QTYPE_STAR == QCLASS_STAR
name = "*";
}
if (name == null) {
name = Integer.toString(val);
}
return name;
}
private static int nameToValue(String name, String[] names) {
if (name.equals("")) {
return -1; // invalid name
} else if (name.equals("*")) {
return QTYPE_STAR; // QTYPE_STAR == QCLASS_STAR
}
if (Character.isDigit(name.charAt(0))) {
try {
return Integer.parseInt(name);
} catch (NumberFormatException e) {
}
}
for (int i = 1; i < names.length; i++) {
if ((names[i] != null) &&
name.equalsIgnoreCase(names[i])) {
return i;
}
}
return -1; // unknown name
}
/*
* Compares two SOA record serial numbers using 32-bit serial number
* arithmetic as defined in RFC 1982. Serial numbers are unsigned
* 32-bit quantities. Returns a negative, zero, or positive value
* as the first serial number is less than, equal to, or greater
* than the second. If the serial numbers are not comparable the
* result is undefined. Note that the relation is not transitive.
*/
public static int compareSerialNumbers(long s1, long s2) {
long diff = s2 - s1;
if (diff == 0) {
return 0;
} else if ((diff > 0 && diff <= 0x7FFFFFFF) ||
(diff < 0 && -diff > 0x7FFFFFFF)) {
return -1;
} else {
return 1;
}
}
/*
* Decodes the binary format of the RR.
* May throw ArrayIndexOutOfBoundsException given corrupt data.
*/
private void decode(boolean decodeRdata) throws InvalidNameException {
int pos = offset; // index of next unread octet
name = new DnsName(); // NAME
pos = decodeName(pos, name);
rrtype = getUShort(pos); // TYPE
rrtypeName = (rrtype < rrTypeNames.length)
? rrTypeNames[rrtype]
: null;
if (rrtypeName == null) {
rrtypeName = Integer.toString(rrtype);
}
pos += 2;
rrclass = getUShort(pos); // CLASS
rrclassName = (rrclass < rrClassNames.length)
? rrClassNames[rrclass]
: null;
if (rrclassName == null) {
rrclassName = Integer.toString(rrclass);
}
pos += 2;
if (!qSection) {
ttl = getInt(pos); // TTL
pos += 4;
rdlen = getUShort(pos); // RDLENGTH
pos += 2;
rdata = (decodeRdata || // RDATA
(rrtype == TYPE_SOA))
? decodeRdata(pos)
: null;
if (rdata instanceof DnsName) {
rdata = rdata.toString();
}
pos += rdlen;
}
rrlen = pos - offset;
msg = null; // free up for GC
}
/*
* Returns the 1-byte unsigned value at msg[pos].
*/
private int getUByte(int pos) {
return (msg[pos] & 0xFF);
}
/*
* Returns the 2-byte unsigned value at msg[pos]. The high
* order byte comes first.
*/
private int getUShort(int pos) {
return (((msg[pos] & 0xFF) << 8) |
(msg[pos + 1] & 0xFF));
}
/*
* Returns the 4-byte signed value at msg[pos]. The high
* order byte comes first.
*/
private int getInt(int pos) {
return ((getUShort(pos) << 16) | getUShort(pos + 2));
}
/*
* Returns the 4-byte unsigned value at msg[pos]. The high
* order byte comes first.
*/
private long getUInt(int pos) {
return (getInt(pos) & 0xffffffffL);
}
/*
* Returns the name encoded at msg[pos], including the root label.
*/
private DnsName decodeName(int pos) throws InvalidNameException {
DnsName n = new DnsName();
decodeName(pos, n);
return n;
}
/*
* Prepends to "n" the domain name encoded at msg[pos], including the root
* label. Returns the index into "msg" following the name.
*/
private int decodeName(int pos, DnsName n) throws InvalidNameException {
if (msg[pos] == 0) { // end of name
n.add(0, "");
return (pos + 1);
} else if ((msg[pos] & 0xC0) != 0) { // name compression
decodeName(getUShort(pos) & 0x3FFF, n);
return (pos + 2);
} else { // append a label
int len = msg[pos++];
try {
n.add(0, new String(msg, pos, len, "ISO-8859-1"));
} catch (java.io.UnsupportedEncodingException e) {
// assert false : "ISO-Latin-1 charset unavailable";
}
return decodeName(pos + len, n);
}
}
/*
* Returns the rdata encoded at msg[pos]. The format is dependent
* on the rrtype and rrclass values, which have already been set.
* The length of the encoded data is rdlen, which has already been
* set.
* The rdata of records with unknown type/class combinations is
* returned in a newly-allocated byte array.
*/
private Object decodeRdata(int pos) throws InvalidNameException {
if (rrclass == CLASS_INTERNET) {
switch (rrtype) {
case TYPE_A:
return decodeA(pos);
case TYPE_AAAA:
return decodeAAAA(pos);
case TYPE_CNAME:
case TYPE_NS:
case TYPE_PTR:
return decodeName(pos);
case TYPE_MX:
return decodeMx(pos);
case TYPE_SOA:
return decodeSoa(pos);
case TYPE_SRV:
return decodeSrv(pos);
case TYPE_NAPTR:
return decodeNaptr(pos);
case TYPE_TXT:
return decodeTxt(pos);
case TYPE_HINFO:
return decodeHinfo(pos);
}
}
// Unknown RR type/class
byte[] rd = new byte[rdlen];
System.arraycopy(msg, pos, rd, 0, rdlen);
return rd;
}
/*
* Returns the rdata of an MX record that is encoded at msg[pos].
*/
private String decodeMx(int pos) throws InvalidNameException {
int preference = getUShort(pos);
pos += 2;
DnsName name = decodeName(pos);
return (preference + " " + name);
}
/*
* Returns the rdata of an SOA record that is encoded at msg[pos].
*/
private String decodeSoa(int pos) throws InvalidNameException {
DnsName mname = new DnsName();
pos = decodeName(pos, mname);
DnsName rname = new DnsName();
pos = decodeName(pos, rname);
long serial = getUInt(pos);
pos += 4;
long refresh = getUInt(pos);
pos += 4;
long retry = getUInt(pos);
pos += 4;
long expire = getUInt(pos);
pos += 4;
long minimum = getUInt(pos); // now used as negative TTL
pos += 4;
return (mname + " " + rname + " " + serial + " " +
refresh + " " + retry + " " + expire + " " + minimum);
}
/*
* Returns the rdata of an SRV record that is encoded at msg[pos].
* See RFC 2782.
*/
private String decodeSrv(int pos) throws InvalidNameException {
int priority = getUShort(pos);
pos += 2;
int weight = getUShort(pos);
pos += 2;
int port = getUShort(pos);
pos += 2;
DnsName target = decodeName(pos);
return (priority + " " + weight + " " + port + " " + target);
}
/*
* Returns the rdata of an NAPTR record that is encoded at msg[pos].
* See RFC 2915.
*/
private String decodeNaptr(int pos) throws InvalidNameException {
int order = getUShort(pos);
pos += 2;
int preference = getUShort(pos);
pos += 2;
StringBuffer flags = new StringBuffer();
pos += decodeCharString(pos, flags);
StringBuffer services = new StringBuffer();
pos += decodeCharString(pos, services);
StringBuffer regexp = new StringBuffer(rdlen);
pos += decodeCharString(pos, regexp);
DnsName replacement = decodeName(pos);
return (order + " " + preference + " " + flags + " " +
services + " " + regexp + " " + replacement);
}
/*
* Returns the rdata of a TXT record that is encoded at msg[pos].
* The rdata consists of one or more <character-string>s.
*/
private String decodeTxt(int pos) {
StringBuffer buf = new StringBuffer(rdlen);
int end = pos + rdlen;
while (pos < end) {
pos += decodeCharString(pos, buf);
if (pos < end) {
buf.append(' ');
}
}
return buf.toString();
}
/*
* Returns the rdata of an HINFO record that is encoded at msg[pos].
* The rdata consists of two <character-string>s.
*/
private String decodeHinfo(int pos) {
StringBuffer buf = new StringBuffer(rdlen);
pos += decodeCharString(pos, buf);
buf.append(' ');
pos += decodeCharString(pos, buf);
return buf.toString();
}
/*
* Decodes the <character-string> at msg[pos] and adds it to buf.
* If the string contains one of the meta-characters ' ', '\\', or
* '"', then the result is quoted and any embedded '\\' or '"'
* chars are escaped with '\\'. Empty strings are also quoted.
* Returns the size of the encoded string, including the initial
* length octet.
*/
private int decodeCharString(int pos, StringBuffer buf) {
int start = buf.length(); // starting index of this string
int len = getUByte(pos++); // encoded string length
boolean quoted = (len == 0); // quote string if empty
for (int i = 0; i < len; i++) {
int c = getUByte(pos++);
quoted |= (c == ' ');
if ((c == '\\') || (c == '"')) {
quoted = true;
buf.append('\\');
}
buf.append((char) c);
}
if (quoted) {
buf.insert(start, '"');
buf.append('"');
}
return (len + 1); // size includes initial octet
}
/*
* Returns the rdata of an A record, in dotted-decimal format,
* that is encoded at msg[pos].
*/
private String decodeA(int pos) {
return ((msg[pos] & 0xff) + "." +
(msg[pos + 1] & 0xff) + "." +
(msg[pos + 2] & 0xff) + "." +
(msg[pos + 3] & 0xff));
}
/*
* Returns the rdata of an AAAA record, in colon-separated format,
* that is encoded at msg[pos]. For example: 4321:0:1:2:3:4:567:89ab.
* See RFCs 1886 and 2373.
*/
private String decodeAAAA(int pos) {
int[] addr6 = new int[8]; // the unsigned 16-bit words of the address
for (int i = 0; i < 8; i++) {
addr6[i] = getUShort(pos);
pos += 2;
}
// Find longest sequence of two or more zeros, to compress them.
int curBase = -1;
int curLen = 0;
int bestBase = -1;
int bestLen = 0;
for (int i = 0; i < 8; i++) {
if (addr6[i] == 0) {
if (curBase == -1) { // new sequence
curBase = i;
curLen = 1;
} else { // extend sequence
++curLen;
if ((curLen >= 2) && (curLen > bestLen)) {
bestBase = curBase;
bestLen = curLen;
}
}
} else { // not in sequence
curBase = -1;
}
}
// If addr begins with at least 6 zeros and is not :: or ::1,
// or with 5 zeros followed by 0xffff, use the text format for
// IPv4-compatible or IPv4-mapped addresses.
if (bestBase == 0) {
if ((bestLen == 6) ||
((bestLen == 7) && (addr6[7] > 1))) {
return ("::" + decodeA(pos - 4));
} else if ((bestLen == 5) && (addr6[5] == 0xffff)) {
return ("::ffff:" + decodeA(pos - 4));
}
}
// If bestBase != -1, compress zeros in [bestBase, bestBase+bestLen)
boolean compress = (bestBase != -1);
StringBuffer buf = new StringBuffer(40);
if (bestBase == 0) {
buf.append(':');
}
for (int i = 0; i < 8; i++) {
if (!compress || (i < bestBase) || (i >= bestBase + bestLen)) {
buf.append(Integer.toHexString(addr6[i]));
if (i < 7) {
buf.append(':');
}
} else if (compress && (i == bestBase)) { // first compressed zero
buf.append(':');
}
}
return buf.toString();
}
}
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