// Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org)
package org.xbill.DNS;
import org.xbill.DNS.utils.HMAC;
import org.xbill.DNS.utils.base64;
import java.util.Date;
/**
* Transaction signature handling. This class generates and verifies
* TSIG records on messages, which provide transaction security.
* @see TSIGRecord
*
* @author Brian Wellington
*/
public class TSIG {
private static final String HMAC_MD5_STR = "HMAC-MD5.SIG-ALG.REG.INT.";
private static final String HMAC_SHA1_STR = "hmac-sha1.";
private static final String HMAC_SHA256_STR = "hmac-sha256.";
/** The domain name representing the HMAC-MD5 algorithm. */
public static final Name HMAC_MD5 = Name.fromConstantString(HMAC_MD5_STR);
/** The domain name representing the HMAC-MD5 algorithm (deprecated). */
public static final Name HMAC = HMAC_MD5;
/** The domain name representing the HMAC-SHA1 algorithm. */
public static final Name HMAC_SHA1 = Name.fromConstantString(HMAC_SHA1_STR);
/** The domain name representing the HMAC-SHA256 algorithm. */
public static final Name HMAC_SHA256 = Name.fromConstantString(HMAC_SHA256_STR);
/**
* The default fudge value for outgoing packets. Can be overriden by the
* tsigfudge option.
*/
public static final short FUDGE = 300;
private Name name, alg;
private String digest;
private byte [] key;
private void
getDigest() {
if (alg.equals(HMAC_MD5))
digest = "md5";
else if (alg.equals(HMAC_SHA1))
digest = "sha-1";
else if (alg.equals(HMAC_SHA256))
digest = "sha-256";
else
throw new IllegalArgumentException("Invalid algorithm");
}
/**
* Creates a new TSIG key, which can be used to sign or verify a message.
* @param algorithm The algorithm of the shared key.
* @param name The name of the shared key.
* @param key The shared key's data.
*/
public
TSIG(Name algorithm, Name name, byte [] key) {
this.name = name;
this.alg = algorithm;
this.key = key;
getDigest();
}
/**
* Creates a new TSIG key with the hmac-md5 algorithm, which can be used to
* sign or verify a message.
* @param name The name of the shared key.
* @param key The shared key's data.
*/
public
TSIG(Name name, byte [] key) {
this(HMAC_MD5, name, key);
}
/**
* Creates a new TSIG object, which can be used to sign or verify a message.
* @param name The name of the shared key.
* @param key The shared key's data represented as a base64 encoded string.
* @throws IllegalArgumentException The key name is an invalid name
* @throws IllegalArgumentException The key data is improperly encoded
*/
public
TSIG(Name algorithm, String name, String key) {
this.key = base64.fromString(key);
if (this.key == null)
throw new IllegalArgumentException("Invalid TSIG key string");
try {
this.name = Name.fromString(name, Name.root);
}
catch (TextParseException e) {
throw new IllegalArgumentException("Invalid TSIG key name");
}
this.alg = algorithm;
getDigest();
}
/**
* Creates a new TSIG object, which can be used to sign or verify a message.
* @param name The name of the shared key. The legal values are "hmac-md5",
* "hmac-sha1", and "hmac-sha256".
* @param key The shared key's data represented as a base64 encoded string.
* @throws IllegalArgumentException The key name is an invalid name
* @throws IllegalArgumentException The key data is improperly encoded
*/
public
TSIG(String algorithm, String name, String key) {
this(HMAC_MD5, name, key);
if (algorithm.equalsIgnoreCase("hmac-md5"))
this.alg = HMAC_MD5;
else if (algorithm.equalsIgnoreCase("hmac-sha1"))
this.alg = HMAC_SHA1;
else if (algorithm.equalsIgnoreCase("hmac-sha256"))
this.alg = HMAC_SHA256;
else
throw new IllegalArgumentException("Invalid TSIG algorithm");
getDigest();
}
/**
* Creates a new TSIG object with the hmac-md5 algorithm, which can be used to
* sign or verify a message.
* @param name The name of the shared key
* @param key The shared key's data, represented as a base64 encoded string.
* @throws IllegalArgumentException The key name is an invalid name
* @throws IllegalArgumentException The key data is improperly encoded
*/
public
TSIG(String name, String key) {
this(HMAC_MD5, name, key);
}
/**
* Creates a new TSIG object with the hmac-md5 algorithm, which can be used to
* sign or verify a message.
* @param str The TSIG key, in the form name:secret, name/secret,
* alg:name:secret, or alg/name/secret. If an algorithm is specified, it must
* be "hmac-md5", "hmac-sha1", or "hmac-sha256".
* @throws IllegalArgumentException The string does not contain both a name
* and secret.
* @throws IllegalArgumentException The key name is an invalid name
* @throws IllegalArgumentException The key data is improperly encoded
*/
static public TSIG
fromString(String str) {
String [] parts = str.split("[:/]");
if (parts.length < 2 || parts.length > 3)
throw new IllegalArgumentException("Invalid TSIG key " +
"specification");
if (parts.length == 3)
return new TSIG(parts[0], parts[1], parts[2]);
else
return new TSIG(HMAC_MD5, parts[0], parts[1]);
}
/**
* Generates a TSIG record with a specific error for a message that has
* been rendered.
* @param m The message
* @param b The rendered message
* @param error The error
* @param old If this message is a response, the TSIG from the request
* @return The TSIG record to be added to the message
*/
public TSIGRecord
generate(Message m, byte [] b, int error, TSIGRecord old) {
Date timeSigned;
if (error != Rcode.BADTIME)
timeSigned = new Date();
else
timeSigned = old.getTimeSigned();
int fudge;
HMAC hmac = null;
if (error == Rcode.NOERROR || error == Rcode.BADTIME)
hmac = new HMAC(digest, key);
fudge = Options.intValue("tsigfudge");
if (fudge < 0 || fudge > 0x7FFF)
fudge = FUDGE;
if (old != null) {
DNSOutput out = new DNSOutput();
out.writeU16(old.getSignature().length);
if (hmac != null) {
hmac.update(out.toByteArray());
hmac.update(old.getSignature());
}
}
/* Digest the message */
if (hmac != null)
hmac.update(b);
DNSOutput out = new DNSOutput();
name.toWireCanonical(out);
out.writeU16(DClass.ANY); /* class */
out.writeU32(0); /* ttl */
alg.toWireCanonical(out);
long time = timeSigned.getTime() / 1000;
int timeHigh = (int) (time >> 32);
long timeLow = (time & 0xFFFFFFFFL);
out.writeU16(timeHigh);
out.writeU32(timeLow);
out.writeU16(fudge);
out.writeU16(error);
out.writeU16(0); /* No other data */
if (hmac != null)
hmac.update(out.toByteArray());
byte [] signature;
if (hmac != null)
signature = hmac.sign();
else
signature = new byte[0];
byte [] other = null;
if (error == Rcode.BADTIME) {
out = new DNSOutput();
time = new Date().getTime() / 1000;
timeHigh = (int) (time >> 32);
timeLow = (time & 0xFFFFFFFFL);
out.writeU16(timeHigh);
out.writeU32(timeLow);
other = out.toByteArray();
}
return (new TSIGRecord(name, DClass.ANY, 0, alg, timeSigned, fudge,
signature, m.getHeader().getID(), error, other));
}
/**
* Generates a TSIG record with a specific error for a message and adds it
* to the message.
* @param m The message
* @param error The error
* @param old If this message is a response, the TSIG from the request
*/
public void
apply(Message m, int error, TSIGRecord old) {
Record r = generate(m, m.toWire(), error, old);
m.addRecord(r, Section.ADDITIONAL);
m.tsigState = Message.TSIG_SIGNED;
}
/**
* Generates a TSIG record for a message and adds it to the message
* @param m The message
* @param old If this message is a response, the TSIG from the request
*/
public void
apply(Message m, TSIGRecord old) {
apply(m, Rcode.NOERROR, old);
}
/**
* Generates a TSIG record for a message and adds it to the message
* @param m The message
* @param old If this message is a response, the TSIG from the request
*/
public void
applyStream(Message m, TSIGRecord old, boolean first) {
if (first) {
apply(m, old);
return;
}
Date timeSigned = new Date();
int fudge;
HMAC hmac = new HMAC(digest, key);
fudge = Options.intValue("tsigfudge");
if (fudge < 0 || fudge > 0x7FFF)
fudge = FUDGE;
DNSOutput out = new DNSOutput();
out.writeU16(old.getSignature().length);
hmac.update(out.toByteArray());
hmac.update(old.getSignature());
/* Digest the message */
hmac.update(m.toWire());
out = new DNSOutput();
long time = timeSigned.getTime() / 1000;
int timeHigh = (int) (time >> 32);
long timeLow = (time & 0xFFFFFFFFL);
out.writeU16(timeHigh);
out.writeU32(timeLow);
out.writeU16(fudge);
hmac.update(out.toByteArray());
byte [] signature = hmac.sign();
byte [] other = null;
Record r = new TSIGRecord(name, DClass.ANY, 0, alg, timeSigned, fudge,
signature, m.getHeader().getID(),
Rcode.NOERROR, other);
m.addRecord(r, Section.ADDITIONAL);
m.tsigState = Message.TSIG_SIGNED;
}
/**
* Verifies a TSIG record on an incoming message. Since this is only called
* in the context where a TSIG is expected to be present, it is an error
* if one is not present. After calling this routine, Message.isVerified() may
* be called on this message.
* @param m The message
* @param b An array containing the message in unparsed form. This is
* necessary since TSIG signs the message in wire format, and we can't
* recreate the exact wire format (with the same name compression).
* @param length The length of the message in the array.
* @param old If this message is a response, the TSIG from the request
* @return The result of the verification (as an Rcode)
* @see Rcode
*/
public byte
verify(Message m, byte [] b, int length, TSIGRecord old) {
m.tsigState = Message.TSIG_FAILED;
TSIGRecord tsig = m.getTSIG();
HMAC hmac = new HMAC(digest, key);
if (tsig == null)
return Rcode.FORMERR;
if (!tsig.getName().equals(name) || !tsig.getAlgorithm().equals(alg)) {
if (Options.check("verbose"))
System.err.println("BADKEY failure");
return Rcode.BADKEY;
}
long now = System.currentTimeMillis();
long then = tsig.getTimeSigned().getTime();
long fudge = tsig.getFudge();
if (Math.abs(now - then) > fudge * 1000) {
if (Options.check("verbose"))
System.err.println("BADTIME failure");
return Rcode.BADTIME;
}
if (old != null && tsig.getError() != Rcode.BADKEY &&
tsig.getError() != Rcode.BADSIG)
{
DNSOutput out = new DNSOutput();
out.writeU16(old.getSignature().length);
hmac.update(out.toByteArray());
hmac.update(old.getSignature());
}
m.getHeader().decCount(Section.ADDITIONAL);
byte [] header = m.getHeader().toWire();
m.getHeader().incCount(Section.ADDITIONAL);
hmac.update(header);
int len = m.tsigstart - header.length;
hmac.update(b, header.length, len);
DNSOutput out = new DNSOutput();
tsig.getName().toWireCanonical(out);
out.writeU16(tsig.dclass);
out.writeU32(tsig.ttl);
tsig.getAlgorithm().toWireCanonical(out);
long time = tsig.getTimeSigned().getTime() / 1000;
int timeHigh = (int) (time >> 32);
long timeLow = (time & 0xFFFFFFFFL);
out.writeU16(timeHigh);
out.writeU32(timeLow);
out.writeU16(tsig.getFudge());
out.writeU16(tsig.getError());
if (tsig.getOther() != null) {
out.writeU16(tsig.getOther().length);
out.writeByteArray(tsig.getOther());
} else {
out.writeU16(0);
}
hmac.update(out.toByteArray());
if (hmac.verify(tsig.getSignature())) {
m.tsigState = Message.TSIG_VERIFIED;
return Rcode.NOERROR;
} else {
if (Options.check("verbose"))
System.err.println("BADSIG failure");
return Rcode.BADSIG;
}
}
/**
* Verifies a TSIG record on an incoming message. Since this is only called
* in the context where a TSIG is expected to be present, it is an error
* if one is not present. After calling this routine, Message.isVerified() may
* be called on this message.
* @param m The message
* @param b The message in unparsed form. This is necessary since TSIG
* signs the message in wire format, and we can't recreate the exact wire
* format (with the same name compression).
* @param old If this message is a response, the TSIG from the request
* @return The result of the verification (as an Rcode)
* @see Rcode
*/
public int
verify(Message m, byte [] b, TSIGRecord old) {
return verify(m, b, b.length, old);
}
/**
* Returns the maximum length of a TSIG record generated by this key.
* @see TSIGRecord
*/
public int
recordLength() {
return (name.length() + 10 +
alg.length() +
8 + // time signed, fudge
18 + // 2 byte MAC length, 16 byte MAC
4 + // original id, error
8); // 2 byte error length, 6 byte max error field.
}
public static class StreamVerifier {
/**
* A helper class for verifying multiple message responses.
*/
private TSIG key;
private HMAC verifier;
private int nresponses;
private int lastsigned;
private TSIGRecord lastTSIG;
/** Creates an object to verify a multiple message response */
public
StreamVerifier(TSIG tsig, TSIGRecord old) {
key = tsig;
verifier = new HMAC(key.digest, key.key);
nresponses = 0;
lastTSIG = old;
}
/**
* Verifies a TSIG record on an incoming message that is part of a
* multiple message response.
* TSIG records must be present on the first and last messages, and
* at least every 100 records in between.
* After calling this routine, Message.isVerified() may be called on
* this message.
* @param m The message
* @param b The message in unparsed form
* @return The result of the verification (as an Rcode)
* @see Rcode
*/
public int
verify(Message m, byte [] b) {
TSIGRecord tsig = m.getTSIG();
nresponses++;
if (nresponses == 1) {
int result = key.verify(m, b, lastTSIG);
if (result == Rcode.NOERROR) {
byte [] signature = tsig.getSignature();
DNSOutput out = new DNSOutput();
out.writeU16(signature.length);
verifier.update(out.toByteArray());
verifier.update(signature);
}
lastTSIG = tsig;
return result;
}
if (tsig != null)
m.getHeader().decCount(Section.ADDITIONAL);
byte [] header = m.getHeader().toWire();
if (tsig != null)
m.getHeader().incCount(Section.ADDITIONAL);
verifier.update(header);
int len;
if (tsig == null)
len = b.length - header.length;
else
len = m.tsigstart - header.length;
verifier.update(b, header.length, len);
if (tsig != null) {
lastsigned = nresponses;
lastTSIG = tsig;
}
else {
boolean required = (nresponses - lastsigned >= 100);
if (required) {
m.tsigState = Message.TSIG_FAILED;
return Rcode.FORMERR;
} else {
m.tsigState = Message.TSIG_INTERMEDIATE;
return Rcode.NOERROR;
}
}
if (!tsig.getName().equals(key.name) ||
!tsig.getAlgorithm().equals(key.alg))
{
if (Options.check("verbose"))
System.err.println("BADKEY failure");
m.tsigState = Message.TSIG_FAILED;
return Rcode.BADKEY;
}
DNSOutput out = new DNSOutput();
long time = tsig.getTimeSigned().getTime() / 1000;
int timeHigh = (int) (time >> 32);
long timeLow = (time & 0xFFFFFFFFL);
out.writeU16(timeHigh);
out.writeU32(timeLow);
out.writeU16(tsig.getFudge());
verifier.update(out.toByteArray());
if (verifier.verify(tsig.getSignature()) == false) {
if (Options.check("verbose"))
System.err.println("BADSIG failure");
return Rcode.BADSIG;
}
verifier.clear();
out = new DNSOutput();
out.writeU16(tsig.getSignature().length);
verifier.update(out.toByteArray());
verifier.update(tsig.getSignature());
return Rcode.NOERROR;
}
}
}