package be.neutrinet.ispng.dns;
import be.neutrinet.ispng.DNS;
import org.apache.log4j.Logger;
import org.xbill.DNS.*;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
/**
* Created by wannes on 1/25/15.
*/
public class RequestHandler {
static final int FLAG_DNSSECOK = 1;
static final int FLAG_SIGONLY = 2;
private Map<Integer, Cache> caches = new HashMap<>();
public Cache getCache(int dclass) {
Cache c = caches.get(dclass);
if (c == null) {
c = new Cache(dclass);
caches.put(dclass, c);
}
return c;
}
public Zone findBestZone(Name name) {
Zone foundzone = null;
foundzone = DNS.zones.get(name);
if (foundzone != null)
return foundzone;
int labels = name.labels();
for (int i = 1; i < labels; i++) {
Name tname = new Name(name, i);
foundzone = DNS.zones.get(tname);
if (foundzone != null)
return foundzone;
}
return null;
}
public RRset findExactMatch(Name name, int type, int dclass, boolean glue) {
Zone zone = findBestZone(name);
if (zone != null)
return zone.findExactMatch(name, type);
else {
RRset[] rrsets;
Cache cache = getCache(dclass);
if (glue)
rrsets = cache.findAnyRecords(name, type);
else
rrsets = cache.findRecords(name, type);
if (rrsets == null)
return null;
else
return rrsets[0]; /* not quite right */
}
}
void addRRset(Name name, Message response, RRset rrset, int section, int flags) {
for (int s = 1; s <= section; s++)
if (response.findRRset(name, rrset.getType(), s))
return;
if ((flags & FLAG_SIGONLY) == 0) {
Iterator it = rrset.rrs();
while (it.hasNext()) {
Record r = (Record) it.next();
if (r.getName().isWild() && !name.isWild())
r = r.withName(name);
response.addRecord(r, section);
}
}
if ((flags & (FLAG_SIGONLY | FLAG_DNSSECOK)) != 0) {
Iterator it = rrset.sigs();
while (it.hasNext()) {
Record r = (Record) it.next();
if (r.getName().isWild() && !name.isWild())
r = r.withName(name);
response.addRecord(r, section);
}
}
}
private final void addSOA(Message response, Zone zone) {
response.addRecord(zone.getSOA(), Section.AUTHORITY);
}
private final void addNS(Message response, Zone zone, int flags) {
RRset nsRecords = zone.getNS();
addRRset(nsRecords.getName(), response, nsRecords,
Section.AUTHORITY, flags);
}
private final void addCacheNS(Message response, Cache cache, Name name) {
SetResponse sr = cache.lookupRecords(name, Type.NS, Credibility.HINT);
if (!sr.isDelegation())
return;
RRset nsRecords = sr.getNS();
Iterator it = nsRecords.rrs();
while (it.hasNext()) {
Record r = (Record) it.next();
response.addRecord(r, Section.AUTHORITY);
}
}
private void addGlue(Message response, Name name, int flags) {
RRset a = findExactMatch(name, Type.A, DClass.IN, true);
if (a == null)
return;
addRRset(name, response, a, Section.ADDITIONAL, flags);
}
private void addAdditional2(Message response, int section, int flags) {
Record[] Records = response.getSectionArray(section);
for (Record r : Records) {
Name glueName = r.getAdditionalName();
if (glueName != null)
addGlue(response, glueName, flags);
}
}
private final void addAdditional(Message response, int flags) {
addAdditional2(response, Section.ANSWER, flags);
addAdditional2(response, Section.AUTHORITY, flags);
}
byte addAnswer(Message response, Name name, int type, int dclass,
int iterations, int flags) {
SetResponse sr;
byte rcode = Rcode.NOERROR;
if (iterations > 6)
return Rcode.NOERROR;
if (type == Type.SIG || type == Type.RRSIG) {
type = Type.ANY;
flags |= FLAG_SIGONLY;
}
Zone zone = findBestZone(name);
if (zone != null)
sr = zone.findRecords(name, type);
else {
Cache cache = getCache(dclass);
sr = cache.lookupRecords(name, type, Credibility.NORMAL);
}
if (sr.isUnknown()) {
addCacheNS(response, getCache(dclass), name);
}
if (sr.isNXDOMAIN()) {
response.getHeader().setRcode(Rcode.NXDOMAIN);
if (zone != null) {
addSOA(response, zone);
if (iterations == 0)
response.getHeader().setFlag(Flags.AA);
}
rcode = Rcode.NXDOMAIN;
} else if (sr.isNXRRSET()) {
if (zone != null) {
addSOA(response, zone);
if (iterations == 0)
response.getHeader().setFlag(Flags.AA);
}
} else if (sr.isDelegation()) {
RRset nsRecords = sr.getNS();
addRRset(nsRecords.getName(), response, nsRecords,
Section.AUTHORITY, flags);
} else if (sr.isCNAME()) {
CNAMERecord cname = sr.getCNAME();
RRset rrset = new RRset(cname);
addRRset(name, response, rrset, Section.ANSWER, flags);
if (zone != null && iterations == 0)
response.getHeader().setFlag(Flags.AA);
rcode = addAnswer(response, cname.getTarget(),
type, dclass, iterations + 1, flags);
} else if (sr.isDNAME()) {
DNAMERecord dname = sr.getDNAME();
RRset rrset = new RRset(dname);
addRRset(name, response, rrset, Section.ANSWER, flags);
Name newname;
try {
newname = name.fromDNAME(dname);
} catch (NameTooLongException e) {
return Rcode.YXDOMAIN;
}
rrset = new RRset(new CNAMERecord(name, dclass, 0, newname));
addRRset(name, response, rrset, Section.ANSWER, flags);
if (zone != null && iterations == 0)
response.getHeader().setFlag(Flags.AA);
rcode = addAnswer(response, newname, type, dclass,
iterations + 1, flags);
} else if (sr.isSuccessful()) {
RRset[] rrsets = sr.answers();
for (RRset rrset : rrsets)
addRRset(name, response, rrset,
Section.ANSWER, flags);
if (zone != null) {
addNS(response, zone, flags);
if (iterations == 0)
response.getHeader().setFlag(Flags.AA);
} else
addCacheNS(response, getCache(dclass), name);
}
return rcode;
}
protected final byte[] doAXFR(Name name, Message query, TSIG tsig, TSIGRecord qtsig, Socket s) {
Zone zone = DNS.zones.get(name);
boolean first = true;
if (zone == null)
return errorMessage(query, Rcode.REFUSED);
Iterator it = zone.AXFR();
try {
DataOutputStream dataOut;
dataOut = new DataOutputStream(s.getOutputStream());
int id = query.getHeader().getID();
while (it.hasNext()) {
RRset rrset = (RRset) it.next();
Message response = new Message(id);
Header header = response.getHeader();
header.setFlag(Flags.QR);
header.setFlag(Flags.AA);
addRRset(rrset.getName(), response, rrset,
Section.ANSWER, FLAG_DNSSECOK);
if (tsig != null) {
tsig.applyStream(response, qtsig, first);
qtsig = response.getTSIG();
}
first = false;
byte[] out = response.toWire();
dataOut.writeShort(out.length);
dataOut.write(out);
}
Logger.getLogger(getClass()).info("AXFR of " + zone.getOrigin().toString() + " to " + s.getInetAddress().getCanonicalHostName() + " completed");
} catch (IOException ex) {
Logger.getLogger(getClass()).error("AXFR of " + zone.getOrigin().toString() + " failed", ex);
}
try {
s.close();
} catch (IOException ex) {
Logger.getLogger(getClass()).error("Failed to service AXFR", ex);
}
return null;
}
/*
* Note: a null return value means that the caller doesn't need to do
* anything. Currently this only happens if this is an AXFR request over
* TCP.
*/
byte[] generateReply(Message query, byte[] in, int length, Socket s) throws IOException {
Header header;
boolean badversion;
int maxLength;
int flags = 0;
header = query.getHeader();
if (header.getFlag(Flags.QR))
return null;
if (header.getRcode() != Rcode.NOERROR)
return errorMessage(query, Rcode.FORMERR);
if (header.getOpcode() != Opcode.QUERY)
return errorMessage(query, Rcode.NOTIMP);
Record queryDNSRecord = query.getQuestion();
TSIGRecord queryTSIG = query.getTSIG();
TSIG tsig = null;
if (queryTSIG != null) {
tsig = DNS.TSIG.get(queryTSIG.getName().toString());
if (tsig == null || tsig.verify(query, in, length, null) != Rcode.NOERROR) {
Logger.getLogger(getClass()).warn("Invalid TSIG key from " + s.getInetAddress().getCanonicalHostName());
return formerrMessage(in);
}
} else {
Logger.getLogger(getClass()).warn("DNS query without TSIG received from " + s.getInetAddress().getCanonicalHostName());
return formerrMessage(in);
}
OPTRecord queryOPT = query.getOPT();
if (queryOPT != null && queryOPT.getVersion() > 0)
badversion = true;
if (s != null)
maxLength = 65535;
else if (queryOPT != null)
maxLength = Math.max(queryOPT.getPayloadSize(), 512);
else
maxLength = 512;
if (queryOPT != null && (queryOPT.getFlags() & ExtendedFlags.DO) != 0)
flags = FLAG_DNSSECOK;
Message response = new Message(query.getHeader().getID());
response.getHeader().setFlag(Flags.QR);
if (query.getHeader().getFlag(Flags.RD))
response.getHeader().setFlag(Flags.RD);
response.addRecord(queryDNSRecord, Section.QUESTION);
Name name = queryDNSRecord.getName();
int type = queryDNSRecord.getType();
int dclass = queryDNSRecord.getDClass();
if (type == Type.AXFR && s != null)
return doAXFR(name, query, tsig, queryTSIG, s);
if (!Type.isRR(type) && type != Type.ANY)
return errorMessage(query, Rcode.NOTIMP);
byte rcode = addAnswer(response, name, type, dclass, 0, flags);
if (rcode != Rcode.NOERROR && rcode != Rcode.NXDOMAIN)
return errorMessage(query, rcode);
addAdditional(response, flags);
if (queryOPT != null) {
int optflags = (flags == FLAG_DNSSECOK) ? ExtendedFlags.DO : 0;
OPTRecord opt = new OPTRecord((short) 4096, rcode, (byte) 0,
optflags);
response.addRecord(opt, Section.ADDITIONAL);
}
response.setTSIG(tsig, Rcode.NOERROR, queryTSIG);
return response.toWire(maxLength);
}
byte[] buildErrorMessage(Header header, int rcode, Record question) {
Message response = new Message();
response.setHeader(header);
for (int i = 0; i < 4; i++)
response.removeAllRecords(i);
if (rcode == Rcode.SERVFAIL)
response.addRecord(question, Section.QUESTION);
header.setRcode(rcode);
return response.toWire();
}
public byte[] formerrMessage(byte[] in) {
Header header;
try {
header = new Header(in);
} catch (IOException e) {
return null;
}
return buildErrorMessage(header, Rcode.FORMERR, null);
}
public byte[] errorMessage(Message query, int rcode) {
return buildErrorMessage(query.getHeader(), rcode,
query.getQuestion());
}
}