captive-validator/src/com/verisign/tat/dnssec/NSEC3ValUtils.java

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/***************************** -*- Java -*- ********************************\
* *
* Copyright (c) 2009 VeriSign, Inc. All rights reserved. *
* *
* This software is provided solely in connection with the terms of the *
* license agreement. Any other use without the prior express written *
* permission of VeriSign is completely prohibited. The software and *
* documentation are "Commercial Items", as that term is defined in 48 *
* C.F.R. section 2.101, consisting of "Commercial Computer Software" and *
* "Commercial Computer Software Documentation" as such terms are defined *
* in 48 C.F.R. section 252.227-7014(a)(5) and 48 C.F.R. section *
* 252.227-7014(a)(1), and used in 48 C.F.R. section 12.212 and 48 C.F.R. *
* section 227.7202, as applicable. Pursuant to the above and other *
* relevant sections of the Code of Federal Regulations, as applicable, *
* VeriSign's publications, commercial computer software, and commercial *
* computer software documentation are distributed and licensed to United *
* States Government end users with only those rights as granted to all *
* other end users, according to the terms and conditions contained in the *
* license agreement(s) that accompany the products and software *
* documentation. *
* *
\***************************************************************************/
package com.verisign.tat.dnssec;
import com.verisign.tat.dnssec.SignUtils.ByteArrayComparator;
import org.apache.log4j.Logger;
import org.xbill.DNS.*;
import org.xbill.DNS.utils.base32;
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import java.security.NoSuchAlgorithmException;
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import java.util.*;
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public class NSEC3ValUtils {
// FIXME: should probably refactor to handle different NSEC3 parameters more
// efficiently.
// Given a list of NSEC3 RRs, they should be grouped according to
// parameters. The idea is to hash and compare for each group independently,
// instead of having to skip NSEC3 RRs with the wrong parameters.
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private static Name asterisk_label = Name.fromConstantString("*");
private static Logger st_log = Logger.getLogger(NSEC3ValUtils.class);
private static final base32 b32 = new base32(base32.Alphabet.BASE32HEX,
false, false);
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public static boolean supportsHashAlgorithm(int alg) {
if (alg == NSEC3Record.SHA1_DIGEST_ID) {
return true;
}
return false;
}
public static void stripUnknownAlgNSEC3s(List<NSEC3Record> nsec3s) {
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if (nsec3s == null) {
return;
}
for (ListIterator<NSEC3Record> i = nsec3s.listIterator(); i.hasNext();) {
NSEC3Record nsec3 = i.next();
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if (!supportsHashAlgorithm(nsec3.getHashAlgorithm())) {
i.remove();
}
}
}
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public static boolean isOptOut(NSEC3Record nsec3) {
return (nsec3.getFlags() & NSEC3Record.Flags.OPT_OUT) == NSEC3Record.Flags.OPT_OUT;
}
/**
* Given a list of NSEC3Records that are part of a message, determine the
* NSEC3 parameters (hash algorithm, iterations, and salt) present. If there
* is more than one distinct grouping, return null;
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*
* @param nsec3s
* A list of NSEC3Record object.
* @return A set containing a number of objects (NSEC3Parameter objects)
* that correspond to each distinct set of parameters, or null if
* the nsec3s list was empty.
*/
public static NSEC3Parameters nsec3Parameters(List<NSEC3Record> nsec3s) {
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if ((nsec3s == null) || (nsec3s.size() == 0)) {
return null;
}
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NSEC3Parameters params = new NSEC3Parameters((NSEC3Record) nsec3s.get(
0));
ByteArrayComparator bac = new ByteArrayComparator();
for (NSEC3Record nsec3 : nsec3s) {
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if (!params.match(nsec3, bac)) {
return null;
}
}
return params;
}
/**
* Given a hash and an a zone name, construct an NSEC3 ownername.
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*
* @param hash
* The hash of an original name.
* @param zonename
* The zone to use in constructing the NSEC3 name.
* @return The NSEC3 name.
*/
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private static Name hashName(byte [] hash, Name zonename) {
try {
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return new Name(b32.toString(hash).toLowerCase(), zonename);
} catch (TextParseException e) {
// Note, this should never happen.
return null;
}
}
/**
* Given a set of NSEC3 parameters, hash a name.
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*
* @param name
* The name to hash.
* @param params
* The parameters to hash with.
* @return The hash.
*/
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private static byte [] hash(Name name, NSEC3Parameters params) {
try {
return params.hash(name);
} catch (NoSuchAlgorithmException e) {
st_log.warn("Did not recognize hash algorithm: " + params.alg);
return null;
}
}
private static byte[] hash(Name name, NSEC3Record nsec3) {
try {
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return nsec3.hashName(name);
} catch (NoSuchAlgorithmException e) {
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st_log.warn("Did not recognize hash algorithm: " + nsec3.getHashAlgorithm());
return null;
}
}
/**
* Given the name of a closest encloser, return the name *.closest_encloser.
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*
* @param closestEncloser
* The name to start with.
* @return The wildcard name.
*/
private static Name ceWildcard(Name closestEncloser) {
try {
Name wc = Name.concatenate(asterisk_label, closestEncloser);
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return wc;
} catch (NameTooLongException e) {
return null;
}
}
/**
* Given a qname and its proven closest encloser, calculate the "next
* closest" name. Basically, this is the name that is one label longer than
* the closest encloser that is still a subdomain of qname.
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*
* @param qname
* The qname.
* @param closestEncloser
* The closest encloser name.
* @return The next closer name.
*/
private static Name nextClosest(Name qname, Name closestEncloser) {
int strip = qname.labels() - closestEncloser.labels() - 1;
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return (strip > 0) ? new Name(qname, strip) : qname;
}
/**
* Find the NSEC3Record that matches a hash of a name.
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*
* @param hash
* The pre-calculated hash of a name.
* @param zonename
* The name of the zone that the NSEC3s are from.
* @param nsec3s
* A list of NSEC3Records from a given message.
* @param params
* The parameters used for calculating the hash.
* @param bac
* An already allocated ByteArrayComparator, for reuse. This may
* be null.
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*
* @return The matching NSEC3Record, if one is present.
*/
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private static NSEC3Record findMatchingNSEC3(byte [] hash, Name zonename,
List<NSEC3Record> nsec3s, NSEC3Parameters params,
ByteArrayComparator bac) {
Name n = hashName(hash, zonename);
for (NSEC3Record nsec3 : nsec3s) {
// Skip nsec3 records that are using different parameters.
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if (!params.match(nsec3, bac)) {
continue;
}
if (n.equals(nsec3.getName())) {
return nsec3;
}
}
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return null;
}
/**
* Given a hash and a candidate NSEC3Record, determine if that NSEC3Record
* covers the hash. Covers specifically means that the hash is in between
* the owner and next hashes and does not equal either.
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*
* @param nsec3
* The candidate NSEC3Record.
* @param hash
* The precalculated hash.
* @param bac
* An already allocated comparator. This may be null.
* @return True if the NSEC3Record covers the hash.
*/
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private static boolean nsec3Covers(NSEC3Record nsec3, byte [] hash,
ByteArrayComparator bac) {
byte [] owner = hash(nsec3.getName(), nsec3);
byte [] next = nsec3.getNext();
// This is the "normal case: owner < next and owner < hash < next
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if ((bac.compare(owner, hash) < 0) && (bac.compare(hash, next) < 0)) {
return true;
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}
// this is the end of zone case: next < owner && hash > owner || hash <
// next
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if ((bac.compare(next, owner) <= 0) &&
((bac.compare(hash, next) < 0) ||
(bac.compare(owner, hash) < 0))) {
return true;
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}
// Otherwise, the NSEC3 does not cover the hash.
return false;
}
/**
* Given a pre-hashed name, find a covering NSEC3 from among a list of
* NSEC3s.
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*
* @param hash
* The hash to consider.
* @param zonename
* The name of the zone.
* @param nsec3s
* The list of NSEC3s present in a message.
* @param params
* The NSEC3 parameters used to generate the hash -- NSEC3s that
* do not use those parameters will be skipped.
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*
* @return A covering NSEC3 if one is present, null otherwise.
*/
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private static NSEC3Record findCoveringNSEC3(byte [] hash, Name zonename,
List<NSEC3Record> nsec3s, NSEC3Parameters params,
ByteArrayComparator bac) {
ByteArrayComparator comparator = new ByteArrayComparator();
for (NSEC3Record nsec3 : nsec3s) {
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if (!params.match(nsec3, bac)) {
continue;
}
if (nsec3Covers(nsec3, hash, comparator)) {
return nsec3;
}
}
return null;
}
/**
* Given a name and a list of NSEC3s, find the candidate closest encloser.
* This will be the first ancestor of 'name' (including itself) to have a
* matching NSEC3 RR.
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*
* @param name
* The name the start with.
* @param zonename
* The name of the zone that the NSEC3s came from.
* @param nsec3s
* The list of NSEC3s.
* @param nsec3params
* The NSEC3 parameters.
* @param bac
* A pre-allocated comparator. May be null.
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*
* @return A CEResponse containing the closest encloser name and the NSEC3
* RR that matched it, or null if there wasn't one.
*/
private static CEResponse findClosestEncloser(Name name, Name zonename,
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List<NSEC3Record> nsec3s, NSEC3Parameters params,
ByteArrayComparator bac) {
Name n = name;
NSEC3Record nsec3;
// This scans from longest name to shortest, so the first match we find
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// is the only viable candidate.
// FIXME: modify so that the NSEC3 matching the zone apex need not be
// present.
while (n.labels() >= zonename.labels()) {
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nsec3 = findMatchingNSEC3(hash(n, params), zonename,
nsec3s, params, bac);
if (nsec3 != null) {
return new CEResponse(n, nsec3);
}
n = new Name(n, 1);
}
return null;
}
/**
* Given a List of nsec3 RRs, find and prove the closest encloser to qname.
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*
* @param qname
* The qname in question.
* @param zonename
* The name of the zone that the NSEC3 RRs come from.
* @param nsec3s
* The list of NSEC3s found the this response (already verified).
* @param params
* The NSEC3 parameters found in the response.
* @param bac
* A pre-allocated comparator. May be null.
* @param proveDoesNotExist
* If true, then if the closest encloser turns out to be qname,
* then null is returned.
* @return null if the proof isn't completed. Otherwise, return a CEResponse
* object which contains the closest encloser name and the NSEC3
* that matches it.
*/
private static CEResponse proveClosestEncloser(Name qname, Name zonename,
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List<NSEC3Record> nsec3s, NSEC3Parameters params,
ByteArrayComparator bac, boolean proveDoesNotExist) {
CEResponse candidate = findClosestEncloser(qname, zonename, nsec3s,
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params, bac);
if (candidate == null) {
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st_log.debug("proveClosestEncloser: could not find a " +
"candidate for the closest encloser.");
return null;
}
if (candidate.closestEncloser.equals(qname)) {
if (proveDoesNotExist) {
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st_log.debug("proveClosestEncloser: proved that qname existed!");
return null;
}
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// otherwise, we need to nothing else to prove that qname is its own
// closest encloser.
return candidate;
}
// If the closest encloser is actually a delegation, then the response
// should have been a referral. If it is a DNAME, then it should have
// been
// a DNAME response.
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if (candidate.ce_nsec3.hasType(Type.NS) &&
!candidate.ce_nsec3.hasType(Type.SOA)) {
st_log.debug("proveClosestEncloser: closest encloser " +
"was a delegation!");
return null;
}
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if (candidate.ce_nsec3.hasType(Type.DNAME)) {
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st_log.debug("proveClosestEncloser: closest encloser was a DNAME!");
return null;
}
// Otherwise, we need to show that the next closer name is covered.
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Name nextClosest = nextClosest(qname, candidate.closestEncloser);
byte [] nc_hash = hash(nextClosest, params);
candidate.nc_nsec3 = findCoveringNSEC3(nc_hash, zonename, nsec3s,
params, bac);
if (candidate.nc_nsec3 == null) {
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st_log.debug("Could not find proof that the " +
"closest encloser was the closest encloser");
return null;
}
return candidate;
}
private static int maxIterations(int baseAlg, int keysize) {
switch (baseAlg) {
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case DnsSecVerifier.RSA:
if (keysize == 0) {
return 2500; // the max at 4096
}
if (keysize > 2048) {
return 2500;
}
if (keysize > 1024) {
return 500;
}
if (keysize > 0) {
return 150;
}
break;
case DnsSecVerifier.DSA:
if (keysize == 0) {
return 5000; // the max at 2048;
}
if (keysize > 1024) {
return 5000;
}
if (keysize > 0) {
return 1500;
}
break;
}
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return -1;
}
@SuppressWarnings("unchecked")
private static boolean validIterations(NSEC3Parameters nsec3params,
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RRset dnskey_rrset, DnsSecVerifier verifier) {
// for now, we return the maximum iterations based simply on the key
// algorithms that may have been used to sign the NSEC3 RRsets.
int max_iterations = 0;
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for (Iterator i = dnskey_rrset.rrs(); i.hasNext();) {
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DNSKEYRecord dnskey = (DNSKEYRecord) i.next();
int baseAlg = verifier.baseAlgorithm(dnskey.getAlgorithm());
int iters = maxIterations(baseAlg, 0);
max_iterations = (max_iterations < iters) ? iters
: max_iterations;
}
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if (nsec3params.iterations > max_iterations) {
return false;
}
return true;
}
/**
* Determine if all of the NSEC3s in a response are legally ignoreable
* (i.e., their presence should lead to an INSECURE result). Currently, this
* is solely based on iterations.
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*
* @param nsec3s
* The list of NSEC3s. If there is more than one set of NSEC3
* parameters present, this test will not be performed.
* @param dnskey_rrset
* The set of validating DNSKEYs.
* @param verifier
* The verifier used to verify the NSEC3 RRsets. This is solely
* used to map algorithm aliases.
* @return true if all of the NSEC3s can be legally ignored, false if not.
*/
public static boolean allNSEC3sIgnoreable(List<NSEC3Record> nsec3s,
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RRset dnskey_rrset, DnsSecVerifier verifier) {
NSEC3Parameters params = nsec3Parameters(nsec3s);
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if (params == null) {
return false;
}
return !validIterations(params, dnskey_rrset, verifier);
}
/**
* Determine if the set of NSEC3 records provided with a response prove NAME
* ERROR. This means that the NSEC3s prove a) the closest encloser exists,
* b) the direct child of the closest encloser towards qname doesn't exist,
* and c) *.closest encloser does not exist.
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*
* @param nsec3s
* The list of NSEC3s.
* @param qname
* The query name to check against.
* @param zonename
* This is the name of the zone that the NSEC3s belong to. This
* may be discovered in any number of ways. A good one is to use
* the signerName from the NSEC3 record's RRSIG.
* @return SecurityStatus.SECURE of the Name Error is proven by the NSEC3
* RRs, BOGUS if not, INSECURE if all of the NSEC3s could be validly
* ignored.
*/
public static boolean proveNameError(List<NSEC3Record> nsec3s, Name qname,
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Name zonename) {
if ((nsec3s == null) || (nsec3s.size() == 0)) {
return false;
}
NSEC3Parameters nsec3params = nsec3Parameters(nsec3s);
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if (nsec3params == null) {
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st_log.debug("Could not find a single set of " +
"NSEC3 parameters (multiple parameters present).");
return false;
}
ByteArrayComparator bac = new ByteArrayComparator();
// First locate and prove the closest encloser to qname. We will use the
// variant that fails if the closest encloser turns out to be qname.
CEResponse ce = proveClosestEncloser(qname, zonename, nsec3s,
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nsec3params, bac, true);
if (ce == null) {
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st_log.debug("proveNameError: failed to prove a closest encloser.");
return false;
}
// At this point, we know that qname does not exist. Now we need to
// prove
// that the wildcard does not exist.
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Name wc = ceWildcard(ce.closestEncloser);
byte [] wc_hash = hash(wc, nsec3params);
NSEC3Record nsec3 = findCoveringNSEC3(wc_hash, zonename, nsec3s,
nsec3params, bac);
if (nsec3 == null) {
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st_log.debug("proveNameError: could not prove that the " +
"applicable wildcard did not exist.");
return false;
}
return true;
}
/**
* Determine if the NSEC3s provided in a response prove the NOERROR/NODATA
* status. There are a number of different variants to this:
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*
* 1) Normal NODATA -- qname is matched to an NSEC3 record, type is not
* present.
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*
* 2) ENT NODATA -- because there must be NSEC3 record for
* empty-non-terminals, this is the same as #1.
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*
* 3) NSEC3 ownername NODATA -- qname matched an existing, lone NSEC3
* ownername, but qtype was not NSEC3. NOTE: as of nsec-05, this case no
* longer exists.
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*
* 4) Wildcard NODATA -- A wildcard matched the name, but not the type.
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*
* 5) Opt-In DS NODATA -- the qname is covered by an opt-in span and qtype
* == DS. (or maybe some future record with the same parent-side-only
* property)
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*
* @param nsec3s
* The NSEC3Records to consider.
* @param qname
* The qname in question.
* @param qtype
* The qtype in question.
* @param zonename
* The name of the zone that the NSEC3s came from.
* @return true if the NSEC3s prove the proposition.
*/
public static boolean proveNodata(List<NSEC3Record> nsec3s, Name qname,
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int qtype, Name zonename) {
if ((nsec3s == null) || (nsec3s.size() == 0)) {
return false;
}
NSEC3Parameters nsec3params = nsec3Parameters(nsec3s);
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if (nsec3params == null) {
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st_log.debug("could not find a single set of " +
"NSEC3 parameters (multiple parameters present)");
return false;
}
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ByteArrayComparator bac = new ByteArrayComparator();
NSEC3Record nsec3 = findMatchingNSEC3(hash(qname, nsec3params),
zonename, nsec3s, nsec3params, bac);
// Cases 1 & 2.
if (nsec3 != null) {
if (nsec3.hasType(qtype)) {
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st_log.debug(
"proveNodata: Matching NSEC3 proved that type existed!");
return false;
}
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if (nsec3.hasType(Type.CNAME)) {
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st_log.debug("proveNodata: Matching NSEC3 proved " +
"that a CNAME existed!");
return false;
}
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return true;
}
// For cases 3 - 5, we need the proven closest encloser, and it can't
// match qname. Although, at this point, we know that it won't since we
// just checked that.
CEResponse ce = proveClosestEncloser(qname, zonename, nsec3s,
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nsec3params, bac, true);
// At this point, not finding a match or a proven closest encloser is a
// problem.
if (ce == null) {
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st_log.debug("proveNodata: did not match qname, " +
"nor found a proven closest encloser.");
return false;
}
// Case 3: REMOVED
// Case 4:
Name wc = ceWildcard(ce.closestEncloser);
nsec3 = findMatchingNSEC3(hash(wc, nsec3params), zonename, nsec3s,
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nsec3params, bac);
if (nsec3 != null) {
if (nsec3.hasType(qtype)) {
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st_log.debug("proveNodata: matching wildcard had qtype!");
return false;
}
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return true;
}
// Case 5.
if (qtype != Type.DS) {
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st_log.debug("proveNodata: could not find matching NSEC3, " +
"nor matching wildcard, and qtype is not DS -- no more options.");
return false;
}
// We need to make sure that the covering NSEC3 is opt-in.
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if (!isOptOut(ce.nc_nsec3)) {
st_log.debug("proveNodata: covering NSEC3 was not " +
"opt-in in an opt-in DS NOERROR/NODATA case.");
return false;
}
return true;
}
/**
* Prove that a positive wildcard match was appropriate (no direct match
* RRset).
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*
* @param nsec3s
* The NSEC3 records to work with.
* @param qname
* The qname that was matched to the wildcard
* @param zonename
* The name of the zone that the NSEC3s come from.
* @param wildcard
* The purported wildcard that matched.
* @return true if the NSEC3 records prove this case.
*/
public static boolean proveWildcard(List<NSEC3Record> nsec3s, Name qname,
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Name zonename, Name wildcard) {
if ((nsec3s == null) || (nsec3s.size() == 0)) {
return false;
}
if ((qname == null) || (wildcard == null)) {
return false;
}
NSEC3Parameters nsec3params = nsec3Parameters(nsec3s);
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if (nsec3params == null) {
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st_log.debug(
"couldn't find a single set of NSEC3 parameters (multiple parameters present).");
return false;
}
ByteArrayComparator bac = new ByteArrayComparator();
// We know what the (purported) closest encloser is by just looking at
// the
// supposed generating wildcard.
CEResponse candidate = new CEResponse(new Name(wildcard, 1), null);
// Now we still need to prove that the original data did not exist.
// Otherwise, we need to show that the next closer name is covered.
Name nextClosest = nextClosest(qname, candidate.closestEncloser);
candidate.nc_nsec3 = findCoveringNSEC3(hash(nextClosest, nsec3params),
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zonename, nsec3s, nsec3params, bac);
if (candidate.nc_nsec3 == null) {
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st_log.debug("proveWildcard: did not find a covering NSEC3 " +
"that covered the next closer name to " + qname + " from " +
candidate.closestEncloser + " (derived from wildcard " +
wildcard + ")");
return false;
}
return true;
}
/**
* Prove that a DS response either had no DS, or wasn't a delegation point.
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*
* Fundamentally there are two cases here: normal NODATA and Opt-In NODATA.
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*
* @param nsec3s
* The NSEC3 RRs to examine.
* @param qname
* The name of the DS in question.
* @param zonename
* The name of the zone that the NSEC3 RRs come from.
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*
* @return SecurityStatus.SECURE if it was proven that there is no DS in a
* secure (i.e., not opt-in) way, SecurityStatus.INSECURE if there
* was no DS in an insecure (i.e., opt-in) way,
* SecurityStatus.INDETERMINATE if it was clear that this wasn't a
* delegation point, and SecurityStatus.BOGUS if the proofs don't
* work out.
*/
public static byte proveNoDS(List<NSEC3Record> nsec3s, Name qname,
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Name zonename) {
if ((nsec3s == null) || (nsec3s.size() == 0)) {
return SecurityStatus.BOGUS;
}
NSEC3Parameters nsec3params = nsec3Parameters(nsec3s);
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if (nsec3params == null) {
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st_log.debug("couldn't find a single set of " +
"NSEC3 parameters (multiple parameters present).");
return SecurityStatus.BOGUS;
}
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ByteArrayComparator bac = new ByteArrayComparator();
// Look for a matching NSEC3 to qname -- this is the normal NODATA case.
NSEC3Record nsec3 = findMatchingNSEC3(hash(qname, nsec3params),
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zonename, nsec3s, nsec3params, bac);
if (nsec3 != null) {
// If the matching NSEC3 has the SOA bit set, it is from the wrong
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// zone (the child instead of the parent). If it has the DS bit set,
// then we were lied to.
if (nsec3.hasType(Type.SOA) || nsec3.hasType(Type.DS)) {
return SecurityStatus.BOGUS;
}
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// If the NSEC3 RR doesn't have the NS bit set, then this wasn't a
// delegation point.
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if (!nsec3.hasType(Type.NS)) {
return SecurityStatus.INDETERMINATE;
}
// Otherwise, this proves no DS.
return SecurityStatus.SECURE;
}
// Otherwise, we are probably in the opt-in case.
CEResponse ce = proveClosestEncloser(qname, zonename, nsec3s,
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nsec3params, bac, true);
if (ce == null) {
return SecurityStatus.BOGUS;
}
// If we had the closest encloser proof, then we need to check that the
// covering NSEC3 was opt-in -- the proveClosestEncloser step already
// checked to see if the closest encloser was a delegation or DNAME.
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if (isOptOut(ce.nc_nsec3)) {
return SecurityStatus.SECURE;
}
return SecurityStatus.BOGUS;
}
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/**
* This is a class to encapsulate a unique set of NSEC3 parameters:
* algorithm, iterations, and salt.
*/
private static class NSEC3Parameters {
public int alg;
public byte [] salt;
public int iterations;
private NSEC3PARAMRecord nsec3paramrec;
public NSEC3Parameters(NSEC3Record r) {
alg = r.getHashAlgorithm();
salt = r.getSalt();
iterations = r.getIterations();
nsec3paramrec = new NSEC3PARAMRecord(Name.root, DClass.IN, 0,
alg, 0, iterations, salt);
}
public boolean match(NSEC3Record r, ByteArrayComparator bac) {
if (r.getHashAlgorithm() != alg) {
return false;
}
if (r.getIterations() != iterations) {
return false;
}
if ((salt == null) && (r.getSalt() != null)) {
return false;
}
if (salt == null) {
return true;
}
if (bac == null) {
bac = new ByteArrayComparator();
}
return bac.compare(r.getSalt(), salt) == 0;
}
public byte[] hash(Name name) throws NoSuchAlgorithmException {
return nsec3paramrec.hashName(name);
}
}
/**
* This is just a simple class to encapsulate the response to a closest
* encloser proof.
*/
private static class CEResponse {
public Name closestEncloser;
public NSEC3Record ce_nsec3;
public NSEC3Record nc_nsec3;
public CEResponse(Name ce, NSEC3Record nsec3) {
this.closestEncloser = ce;
this.ce_nsec3 = nsec3;
}
}
}