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This OSGi bundle wraps ${pkgArtifactId} ${pkgVersion} jar file.
// SPDX-License-Identifier: BSD-2-Clause
// Copyright (c) 1999-2004 Brian Wellington ([email protected])
package org.xbill.DNS;
import java.io.IOException;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import lombok.extern.slf4j.Slf4j;
/**
* A cache of DNS records. The cache obeys TTLs, so items are purged after their validity period is
* complete. Negative answers are cached, to avoid repeated failed DNS queries. The credibility of
* each RRset is maintained, so that more credible records replace less credible records, and
* lookups can specify the minimum credibility of data they are requesting.
*
* @see RRset
* @see Credibility
* @author Brian Wellington
*/
@Slf4j
public class Cache {
private interface Element {
boolean expired();
int compareCredibility(int cred);
int getType();
}
private static int limitExpire(long ttl, long maxttl) {
if (maxttl >= 0 && maxttl < ttl) {
ttl = maxttl;
}
long expire = (System.currentTimeMillis() / 1000) + ttl;
if (expire < 0 || expire > Integer.MAX_VALUE) {
return Integer.MAX_VALUE;
}
return (int) expire;
}
private static class CacheRRset extends RRset implements Element {
private static final long serialVersionUID = 5971755205903597024L;
int credibility;
int expire;
public CacheRRset(Record rec, int cred, long maxttl) {
super();
this.credibility = cred;
this.expire = limitExpire(rec.getTTL(), maxttl);
addRR(rec);
}
public CacheRRset(RRset rrset, int cred, long maxttl) {
super(rrset);
this.credibility = cred;
this.expire = limitExpire(rrset.getTTL(), maxttl);
}
@Override
public final boolean expired() {
int now = (int) (System.currentTimeMillis() / 1000);
return now >= expire;
}
@Override
public final int compareCredibility(int cred) {
return credibility - cred;
}
@Override
public String toString() {
return super.toString() + " cl = " + credibility;
}
}
private static class NegativeElement implements Element {
int type;
Name name;
int credibility;
int expire;
public NegativeElement(Name name, int type, SOARecord soa, int cred, long maxttl) {
this.name = name;
this.type = type;
long cttl = 0;
if (soa != null) {
cttl = Math.min(soa.getMinimum(), soa.getTTL());
}
this.credibility = cred;
this.expire = limitExpire(cttl, maxttl);
}
@Override
public int getType() {
return type;
}
@Override
public final boolean expired() {
int now = (int) (System.currentTimeMillis() / 1000);
return now >= expire;
}
@Override
public final int compareCredibility(int cred) {
return credibility - cred;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
if (type == 0) {
sb.append("NXDOMAIN ").append(name);
} else {
sb.append("NXRRSET ").append(name).append(" ").append(Type.string(type));
}
sb.append(" cl = ");
sb.append(credibility);
return sb.toString();
}
}
private static class CacheMap extends LinkedHashMap {
private int maxsize;
CacheMap(int maxsize) {
super(16, (float) 0.75, true);
this.maxsize = maxsize;
}
int getMaxSize() {
return maxsize;
}
void setMaxSize(int maxsize) {
/*
* Note that this doesn't shrink the size of the map if
* the maximum size is lowered, but it should shrink as
* entries expire.
*/
this.maxsize = maxsize;
}
@Override
protected boolean removeEldestEntry(Map.Entry eldest) {
return maxsize >= 0 && size() > maxsize;
}
}
private CacheMap data;
private int maxncache = -1;
private int maxcache = -1;
private int dclass;
private static final int defaultMaxEntries = 50000;
/**
* Creates an empty Cache
*
* @param dclass The DNS class of this cache
* @see DClass
*/
public Cache(int dclass) {
this.dclass = dclass;
data = new CacheMap(defaultMaxEntries);
}
/**
* Creates an empty Cache for class IN.
*
* @see DClass
*/
public Cache() {
this(DClass.IN);
}
/** Creates a Cache which initially contains all records in the specified file. */
public Cache(String file) throws IOException {
data = new CacheMap(defaultMaxEntries);
try (Master m = new Master(file)) {
Record record;
while ((record = m.nextRecord()) != null) {
addRecord(record, Credibility.HINT);
}
}
}
private synchronized Object exactName(Name name) {
return data.get(name);
}
private synchronized void removeName(Name name) {
data.remove(name);
}
private synchronized Element[] allElements(Object types) {
if (types instanceof List) {
@SuppressWarnings("unchecked")
List typelist = (List) types;
int size = typelist.size();
return typelist.toArray(new Element[size]);
} else {
Element set = (Element) types;
return new Element[] {set};
}
}
private synchronized Element oneElement(Name name, Object types, int type, int minCred) {
Element found = null;
if (type == Type.ANY) {
throw new IllegalArgumentException("oneElement(ANY)");
}
if (types instanceof List) {
@SuppressWarnings("unchecked")
List list = (List) types;
for (Element set : list) {
if (set.getType() == type) {
found = set;
break;
}
}
} else {
Element set = (Element) types;
if (set.getType() == type) {
found = set;
}
}
if (found == null) {
return null;
}
if (found.expired()) {
removeElement(name, type);
return null;
}
if (found.compareCredibility(minCred) < 0) {
return null;
}
return found;
}
private synchronized Element findElement(Name name, int type, int minCred) {
Object types = exactName(name);
if (types == null) {
return null;
}
return oneElement(name, types, type, minCred);
}
private synchronized void addElement(Name name, Element element) {
Object types = data.get(name);
if (types == null) {
data.put(name, element);
return;
}
int type = element.getType();
if (types instanceof List) {
@SuppressWarnings("unchecked")
List list = (List) types;
for (int i = 0; i < list.size(); i++) {
Element elt = list.get(i);
if (elt.getType() == type) {
list.set(i, element);
return;
}
}
list.add(element);
} else {
Element elt = (Element) types;
if (elt.getType() == type) {
data.put(name, element);
} else {
LinkedList list = new LinkedList<>();
list.add(elt);
list.add(element);
data.put(name, list);
}
}
}
private synchronized void removeElement(Name name, int type) {
Object types = data.get(name);
if (types == null) {
return;
}
if (types instanceof List) {
@SuppressWarnings("unchecked")
List list = (List) types;
for (int i = 0; i < list.size(); i++) {
Element elt = list.get(i);
if (elt.getType() == type) {
list.remove(i);
if (list.size() == 0) {
data.remove(name);
}
return;
}
}
} else {
Element elt = (Element) types;
if (elt.getType() != type) {
return;
}
data.remove(name);
}
}
/** Empties the Cache. */
public synchronized void clearCache() {
data.clear();
}
/**
* Adds a record to the Cache.
*
* @param r The record to be added
* @param cred The credibility of the record
* @param o unused
* @deprecated use {@link #addRecord(Record, int)}
*/
@Deprecated
public synchronized void addRecord(Record r, int cred, Object o) {
addRecord(r, cred);
}
/**
* Adds a record to the Cache.
*
* @param r The record to be added
* @param cred The credibility of the record
* @see Record
*/
public synchronized void addRecord(Record r, int cred) {
Name name = r.getName();
int type = r.getRRsetType();
if (!Type.isRR(type)) {
return;
}
Element element = findElement(name, type, cred);
if (element == null) {
CacheRRset crrset = new CacheRRset(r, cred, maxcache);
addRRset(crrset, cred);
} else if (element.compareCredibility(cred) == 0) {
if (element instanceof CacheRRset) {
CacheRRset crrset = (CacheRRset) element;
crrset.addRR(r);
}
}
}
/**
* Adds an RRset to the Cache.
*
* @param rrset The RRset to be added
* @param cred The credibility of these records
* @see RRset
*/
public synchronized void addRRset(RRset rrset, int cred) {
long ttl = rrset.getTTL();
Name name = rrset.getName();
int type = rrset.getType();
Element element = findElement(name, type, 0);
if (ttl == 0) {
if (element != null && element.compareCredibility(cred) <= 0) {
removeElement(name, type);
}
} else {
if (element != null && element.compareCredibility(cred) <= 0) {
element = null;
}
if (element == null) {
CacheRRset crrset;
if (rrset instanceof CacheRRset) {
crrset = (CacheRRset) rrset;
} else {
crrset = new CacheRRset(rrset, cred, maxcache);
}
addElement(name, crrset);
}
}
}
/**
* Adds a negative entry to the Cache.
*
* @param name The name of the negative entry
* @param type The type of the negative entry
* @param soa The SOA record to add to the negative cache entry, or null. The negative cache ttl
* is derived from the SOA.
* @param cred The credibility of the negative entry
*/
public synchronized void addNegative(Name name, int type, SOARecord soa, int cred) {
long ttl = 0;
if (soa != null) {
ttl = Math.min(soa.getMinimum(), soa.getTTL());
}
Element element = findElement(name, type, 0);
if (ttl == 0) {
if (element != null && element.compareCredibility(cred) <= 0) {
removeElement(name, type);
}
} else {
if (element != null && element.compareCredibility(cred) <= 0) {
element = null;
}
if (element == null) {
addElement(name, new NegativeElement(name, type, soa, cred, maxncache));
}
}
}
/** Finds all matching sets or something that causes the lookup to stop. */
protected synchronized SetResponse lookup(Name name, int type, int minCred) {
int labels;
int tlabels;
Element element;
Name tname;
Object types;
SetResponse sr;
labels = name.labels();
for (tlabels = labels; tlabels >= 1; tlabels--) {
boolean isRoot = tlabels == 1;
boolean isExact = tlabels == labels;
if (isRoot) {
tname = Name.root;
} else if (isExact) {
tname = name;
} else {
tname = new Name(name, labels - tlabels);
}
types = data.get(tname);
if (types == null) {
continue;
}
/*
* If this is the name, look for the actual type or a CNAME
* (unless it's an ANY query, where we return everything).
* Otherwise, look for a DNAME.
*/
if (isExact && type == Type.ANY) {
sr = new SetResponse(SetResponse.SUCCESSFUL);
Element[] elements = allElements(types);
int added = 0;
for (Element value : elements) {
element = value;
if (element.expired()) {
removeElement(tname, element.getType());
continue;
}
if (!(element instanceof CacheRRset)) {
continue;
}
if (element.compareCredibility(minCred) < 0) {
continue;
}
sr.addRRset((CacheRRset) element);
added++;
}
/* There were positive entries */
if (added > 0) {
return sr;
}
} else if (isExact) {
element = oneElement(tname, types, type, minCred);
if (element instanceof CacheRRset) {
sr = new SetResponse(SetResponse.SUCCESSFUL);
sr.addRRset((CacheRRset) element);
return sr;
} else if (element != null) {
sr = new SetResponse(SetResponse.NXRRSET);
return sr;
}
element = oneElement(tname, types, Type.CNAME, minCred);
if (element instanceof CacheRRset) {
return new SetResponse(SetResponse.CNAME, (CacheRRset) element);
}
} else {
element = oneElement(tname, types, Type.DNAME, minCred);
if (element instanceof CacheRRset) {
return new SetResponse(SetResponse.DNAME, (CacheRRset) element);
}
}
/* Look for an NS */
element = oneElement(tname, types, Type.NS, minCred);
if (element instanceof CacheRRset) {
return new SetResponse(SetResponse.DELEGATION, (CacheRRset) element);
}
/* Check for the special NXDOMAIN element. */
if (isExact) {
element = oneElement(tname, types, 0, minCred);
if (element != null) {
return SetResponse.ofType(SetResponse.NXDOMAIN);
}
}
}
return SetResponse.ofType(SetResponse.UNKNOWN);
}
/**
* Looks up Records in the Cache. This follows CNAMEs and handles negatively cached data.
*
* @param name The name to look up
* @param type The type to look up
* @param minCred The minimum acceptable credibility
* @return A SetResponse object
* @see SetResponse
* @see Credibility
*/
public SetResponse lookupRecords(Name name, int type, int minCred) {
return lookup(name, type, minCred);
}
private List findRecords(Name name, int type, int minCred) {
SetResponse cr = lookupRecords(name, type, minCred);
if (cr.isSuccessful()) {
return cr.answers();
} else {
return null;
}
}
/**
* Looks up credible Records in the Cache (a wrapper around lookupRecords). Unlike lookupRecords,
* this given no indication of why failure occurred.
*
* @param name The name to look up
* @param type The type to look up
* @return An array of RRsets, or null
* @see Credibility
*/
public List findRecords(Name name, int type) {
return findRecords(name, type, Credibility.NORMAL);
}
/**
* Looks up Records in the Cache (a wrapper around lookupRecords). Unlike lookupRecords, this
* given no indication of why failure occurred.
*
* @param name The name to look up
* @param type The type to look up
* @return An array of RRsets, or null
* @see Credibility
*/
public List findAnyRecords(Name name, int type) {
return findRecords(name, type, Credibility.GLUE);
}
private int getCred(int section, boolean isAuth) {
if (section == Section.ANSWER) {
if (isAuth) {
return Credibility.AUTH_ANSWER;
} else {
return Credibility.NONAUTH_ANSWER;
}
} else if (section == Section.AUTHORITY) {
if (isAuth) {
return Credibility.AUTH_AUTHORITY;
} else {
return Credibility.NONAUTH_AUTHORITY;
}
} else if (section == Section.ADDITIONAL) {
return Credibility.ADDITIONAL;
} else {
throw new IllegalArgumentException("getCred: invalid section");
}
}
private static void markAdditional(RRset rrset, Set names) {
Record first = rrset.first();
if (first.getAdditionalName() == null) {
return;
}
for (Record r : rrset.rrs()) {
Name name = r.getAdditionalName();
if (name != null) {
names.add(name);
}
}
}
/**
* Adds all data from a Message into the Cache. Each record is added with the appropriate
* credibility, and negative answers are cached as such.
*
* @param in The Message to be added
* @return A SetResponse that reflects what would be returned from a cache lookup, or null if
* nothing useful could be cached from the message.
* @see Message
*/
public SetResponse addMessage(Message in) {
boolean isAuth = in.getHeader().getFlag(Flags.AA);
Record question = in.getQuestion();
Name qname;
Name curname;
int qtype;
int qclass;
int cred;
int rcode = in.getHeader().getRcode();
boolean completed = false;
List answers, auth, addl;
SetResponse response = null;
HashSet additionalNames;
if ((rcode != Rcode.NOERROR && rcode != Rcode.NXDOMAIN) || question == null) {
return null;
}
qname = question.getName();
qtype = question.getType();
qclass = question.getDClass();
curname = qname;
additionalNames = new HashSet<>();
answers = in.getSectionRRsets(Section.ANSWER);
for (RRset answer : answers) {
if (answer.getDClass() != qclass) {
continue;
}
int type = answer.getType();
Name name = answer.getName();
cred = getCred(Section.ANSWER, isAuth);
if ((type == qtype || qtype == Type.ANY) && name.equals(curname)) {
addRRset(answer, cred);
completed = true;
if (curname == qname) {
if (response == null) {
response = new SetResponse(SetResponse.SUCCESSFUL);
}
response.addRRset(answer);
}
markAdditional(answer, additionalNames);
} else if (type == Type.CNAME && name.equals(curname)) {
CNAMERecord cname;
addRRset(answer, cred);
if (curname == qname) {
response = new SetResponse(SetResponse.CNAME, answer);
}
cname = (CNAMERecord) answer.first();
curname = cname.getTarget();
} else if (type == Type.DNAME && curname.subdomain(name)) {
DNAMERecord dname;
addRRset(answer, cred);
if (curname == qname) {
response = new SetResponse(SetResponse.DNAME, answer);
}
dname = (DNAMERecord) answer.first();
try {
curname = curname.fromDNAME(dname);
} catch (NameTooLongException e) {
break;
}
}
}
auth = in.getSectionRRsets(Section.AUTHORITY);
RRset soa = null;
RRset ns = null;
for (RRset rset : auth) {
if (rset.getType() == Type.SOA && curname.subdomain(rset.getName())) {
soa = rset;
} else if (rset.getType() == Type.NS && curname.subdomain(rset.getName())) {
ns = rset;
}
}
if (!completed) {
/* This is a negative response or a referral. */
int cachetype = (rcode == Rcode.NXDOMAIN) ? 0 : qtype;
if (rcode == Rcode.NXDOMAIN || soa != null || ns == null) {
/* Negative response */
cred = getCred(Section.AUTHORITY, isAuth);
SOARecord soarec = null;
if (soa != null) {
soarec = (SOARecord) soa.first();
}
addNegative(curname, cachetype, soarec, cred);
if (response == null) {
int responseType;
if (rcode == Rcode.NXDOMAIN) {
responseType = SetResponse.NXDOMAIN;
} else {
responseType = SetResponse.NXRRSET;
}
response = SetResponse.ofType(responseType);
}
/* DNSSEC records are not cached. */
} else {
/* Referral response */
cred = getCred(Section.AUTHORITY, isAuth);
addRRset(ns, cred);
markAdditional(ns, additionalNames);
if (response == null) {
response = new SetResponse(SetResponse.DELEGATION, ns);
}
}
} else if (rcode == Rcode.NOERROR && ns != null) {
/* Cache the NS set from a positive response. */
cred = getCred(Section.AUTHORITY, isAuth);
addRRset(ns, cred);
markAdditional(ns, additionalNames);
}
addl = in.getSectionRRsets(Section.ADDITIONAL);
for (RRset rRset : addl) {
int type = rRset.getType();
if (type != Type.A && type != Type.AAAA && type != Type.A6) {
continue;
}
Name name = rRset.getName();
if (!additionalNames.contains(name)) {
continue;
}
cred = getCred(Section.ADDITIONAL, isAuth);
addRRset(rRset, cred);
}
log.debug(
"Caching {} for {}/{}",
response,
in.getQuestion().getName(),
Type.string(in.getQuestion().getType()));
return response;
}
/**
* Flushes an RRset from the cache
*
* @param name The name of the records to be flushed
* @param type The type of the records to be flushed
* @see RRset
*/
public void flushSet(Name name, int type) {
removeElement(name, type);
}
/**
* Flushes all RRsets with a given name from the cache
*
* @param name The name of the records to be flushed
* @see RRset
*/
public void flushName(Name name) {
removeName(name);
}
/**
* Sets the maximum length of time that a negative response will be stored in this Cache. A
* negative value disables this feature (that is, sets no limit).
*/
public void setMaxNCache(int seconds) {
maxncache = seconds;
}
/**
* Gets the maximum length of time that a negative response will be stored in this Cache. A
* negative value indicates no limit.
*/
public int getMaxNCache() {
return maxncache;
}
/**
* Sets the maximum length of time that records will be stored in this Cache. A negative value
* disables this feature (that is, sets no limit).
*/
public void setMaxCache(int seconds) {
maxcache = seconds;
}
/**
* Gets the maximum length of time that records will be stored in this Cache. A negative value
* indicates no limit.
*/
public int getMaxCache() {
return maxcache;
}
/**
* Gets the current number of entries in the Cache, where an entry consists of all records with a
* specific Name.
*/
public int getSize() {
return data.size();
}
/**
* Gets the maximum number of entries in the Cache, where an entry consists of all records with a
* specific Name. A negative value is treated as an infinite limit.
*/
public int getMaxEntries() {
return data.getMaxSize();
}
/**
* Sets the maximum number of entries in the Cache, where an entry consists of all records with a
* specific Name. A negative value is treated as an infinite limit.
*
* Note that setting this to a value lower than the current number of entries will not cause
* the Cache to shrink immediately.
*
*
The default maximum number of entries is 50000.
*
* @param entries The maximum number of entries in the Cache.
*/
public void setMaxEntries(int entries) {
data.setMaxSize(entries);
}
/** Returns the DNS class of this cache. */
public int getDClass() {
return dclass;
}
/** Returns the contents of the Cache as a string. */
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
synchronized (this) {
for (Object o : data.values()) {
Element[] elements = allElements(o);
for (Element element : elements) {
sb.append(element);
sb.append("\n");
}
}
}
return sb.toString();
}
}
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