/*
* Copied from the DnsJava project
*
* Copyright (c) 1998-2011, Brian Wellington.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
package io.milton.dns.record;
import io.milton.dns.Name;
import java.io.*;
import java.util.*;
/**
* 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
*/
public class Cache {
private interface Element {
public boolean expired();
public int compareCredibility(int cred);
public 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);
}
public final boolean
expired() {
int now = (int)(System.currentTimeMillis() / 1000);
return (now >= expire);
}
public final int
compareCredibility(int cred) {
return credibility - cred;
}
public String
toString() {
StringBuilder sb = new StringBuilder();
sb.append(super.toString());
sb.append(" cl = ");
sb.append(credibility);
return sb.toString();
}
}
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 = soa.getMinimum();
this.credibility = cred;
this.expire = limitExpire(cttl, maxttl);
}
public int
getType() {
return type;
}
public final boolean
expired() {
int now = (int)(System.currentTimeMillis() / 1000);
return (now >= expire);
}
public final int
compareCredibility(int cred) {
return credibility - cred;
}
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 = -1;
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;
}
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);
Master m = new Master(file);
Record record;
while ((record = m.nextRecord()) != null)
addRecord(record, Credibility.HINT, m);
}
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) {
List typelist = (List) types;
int size = typelist.size();
return (Element []) 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) {
List list = (List) types;
for (int i = 0; i < list.size(); i++) {
Element set = (Element) list.get(i);
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) {
List list = (List) types;
for (int i = 0; i < list.size(); i++) {
Element elt = (Element) 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) {
List list = (List) types;
for (int i = 0; i < list.size(); i++) {
Element elt = (Element) list.get(i);
if (elt.getType() == type) {
list.remove(i);
if (list.isEmpty())
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 The source of the record (this could be a Message, for example)
* @see Record
*/
public synchronized void
addRecord(Record r, int cred, Object o) {
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 = 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 (int i = 0; i < elements.length; i++) {
element = elements[i];
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 != null &&
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 != null &&
element instanceof CacheRRset)
{
return new SetResponse(SetResponse.CNAME,
(CacheRRset) element);
}
} else {
element = oneElement(tname, types, Type.DNAME, minCred);
if (element != null &&
element instanceof CacheRRset)
{
return new SetResponse(SetResponse.DNAME,
(CacheRRset) element);
}
}
/* Look for an NS */
element = oneElement(tname, types, Type.NS, minCred);
if (element != null && 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 RRset []
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 RRset []
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 RRset []
findAnyRecords(Name name, int type) {
return findRecords(name, type, Credibility.GLUE);
}
private final 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;
Iterator it = rrset.rrs();
while (it.hasNext()) {
Record r = (Record) it.next();
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;
RRset [] answers, auth, addl;
SetResponse response = null;
boolean verbose = Options.check("verbosecache");
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 (int i = 0; i < answers.length; i++) {
if (answers[i].getDClass() != qclass)
continue;
int type = answers[i].getType();
Name name = answers[i].getName();
cred = getCred(Section.ANSWER, isAuth);
if ((type == qtype || qtype == Type.ANY) &&
name.equals(curname))
{
addRRset(answers[i], cred);
completed = true;
if (curname == qname) {
if (response == null)
response = new SetResponse(
SetResponse.SUCCESSFUL);
response.addRRset(answers[i]);
}
markAdditional(answers[i], additionalNames);
} else if (type == Type.CNAME && name.equals(curname)) {
CNAMERecord cname;
addRRset(answers[i], cred);
if (curname == qname)
response = new SetResponse(SetResponse.CNAME,
answers[i]);
cname = (CNAMERecord) answers[i].first();
curname = cname.getTarget();
} else if (type == Type.DNAME && curname.subdomain(name)) {
DNAMERecord dname;
addRRset(answers[i], cred);
if (curname == qname)
response = new SetResponse(SetResponse.DNAME,
answers[i]);
dname = (DNAMERecord) answers[i].first();
try {
curname = curname.fromDNAME(dname);
}
catch (NameTooLongException e) {
break;
}
}
}
auth = in.getSectionRRsets(Section.AUTHORITY);
RRset soa = null, ns = null;
for (int i = 0; i < auth.length; i++) {
if (auth[i].getType() == Type.SOA &&
curname.subdomain(auth[i].getName()))
soa = auth[i];
else if (auth[i].getType() == Type.NS &&
curname.subdomain(auth[i].getName()))
ns = auth[i];
}
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 (int i = 0; i < addl.length; i++) {
int type = addl[i].getType();
if (type != Type.A && type != Type.AAAA && type != Type.A6)
continue;
Name name = addl[i].getName();
if (!additionalNames.contains(name))
continue;
cred = getCred(Section.ADDITIONAL, isAuth);
addRRset(addl[i], cred);
}
if (verbose)
System.out.println("addMessage: " + response);
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.
*/
public String
toString() {
StringBuilder sb = new StringBuilder();
synchronized (this) {
Iterator it = data.values().iterator();
while (it.hasNext()) {
Element [] elements = allElements(it.next());
for (int i = 0; i < elements.length; i++) {
sb.append(elements[i]);
sb.append("\n");
}
}
}
return sb.toString();
}
}