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SimpleResolver.java
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SimpleResolver.java
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// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org)
package org.xbill.DNS;
import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.UnknownHostException;
import java.time.Duration;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionStage;
import java.util.concurrent.Executor;
import java.util.concurrent.ForkJoinPool;
import lombok.extern.slf4j.Slf4j;
/**
* An implementation of Resolver that sends one query to one server. SimpleResolver handles TCP
* retries, transaction security (TSIG), and EDNS 0.
*
* @see Resolver
* @see TSIG
* @see OPTRecord
* @author Brian Wellington
*/
@Slf4j
public class SimpleResolver implements Resolver {
/** The default port to send queries to */
public static final int DEFAULT_PORT = 53;
/** The default EDNS payload size */
public static final int DEFAULT_EDNS_PAYLOADSIZE = 1280;
private InetSocketAddress address;
private InetSocketAddress localAddress;
private boolean useTCP;
private boolean ignoreTruncation;
private OPTRecord queryOPT = new OPTRecord(DEFAULT_EDNS_PAYLOADSIZE, 0, 0, 0);
private TSIG tsig;
private Duration timeoutValue = Duration.ofSeconds(10);
private static final short DEFAULT_UDPSIZE = 512;
private static InetSocketAddress defaultResolver =
new InetSocketAddress(InetAddress.getLoopbackAddress(), DEFAULT_PORT);
/**
* Creates a SimpleResolver. The host to query is either found by using ResolverConfig, or the
* default host is used.
*
* @see ResolverConfig
* @exception UnknownHostException Failure occurred while finding the host
*/
public SimpleResolver() throws UnknownHostException {
this((String) null);
}
/**
* Creates a SimpleResolver that will query the specified host
*
* @exception UnknownHostException Failure occurred while finding the host
*/
public SimpleResolver(String hostname) throws UnknownHostException {
if (hostname == null) {
address = ResolverConfig.getCurrentConfig().server();
if (address == null) {
address = defaultResolver;
}
return;
}
InetAddress addr;
if ("0".equals(hostname)) {
addr = InetAddress.getLoopbackAddress();
} else {
addr = InetAddress.getByName(hostname);
}
address = new InetSocketAddress(addr, DEFAULT_PORT);
}
/** Creates a SimpleResolver that will query the specified host */
public SimpleResolver(InetSocketAddress host) {
address = Objects.requireNonNull(host, "host must not be null");
}
/** Creates a SimpleResolver that will query the specified host */
public SimpleResolver(InetAddress host) {
Objects.requireNonNull(host, "host must not be null");
address = new InetSocketAddress(host, DEFAULT_PORT);
}
/**
* Gets the destination address associated with this SimpleResolver. Messages sent using this
* SimpleResolver will be sent to this address.
*
* @return The destination address associated with this SimpleResolver.
*/
public InetSocketAddress getAddress() {
return address;
}
/** Sets the default host (initially localhost) to query */
public static void setDefaultResolver(InetSocketAddress hostname) {
defaultResolver = hostname;
}
/** Sets the default host (initially localhost) to query */
public static void setDefaultResolver(String hostname) {
defaultResolver = new InetSocketAddress(hostname, DEFAULT_PORT);
}
/**
* Gets the port to communicate with on the server
*
* @since 3.2
*/
public int getPort() {
return address.getPort();
}
@Override
public void setPort(int port) {
address = new InetSocketAddress(address.getAddress(), port);
}
/**
* Sets the address of the server to communicate with.
*
* @param addr The address of the DNS server
*/
public void setAddress(InetSocketAddress addr) {
address = addr;
}
/**
* Sets the address of the server to communicate with (on the default DNS port)
*
* @param addr The address of the DNS server
*/
public void setAddress(InetAddress addr) {
address = new InetSocketAddress(addr, address.getPort());
}
/**
* Sets the local address to bind to when sending messages.
*
* @param addr The local address to send messages from.
*/
public void setLocalAddress(InetSocketAddress addr) {
localAddress = addr;
}
/**
* Sets the local address to bind to when sending messages. A random port will be used.
*
* @param addr The local address to send messages from.
*/
public void setLocalAddress(InetAddress addr) {
localAddress = new InetSocketAddress(addr, 0);
}
/**
* Gets whether TCP connections will be used by default
*
* @since 3.2
*/
public boolean getTCP() {
return useTCP;
}
@Override
public void setTCP(boolean flag) {
this.useTCP = flag;
}
/**
* Gets whether truncated responses will be ignored.
*
* @since 3.2
*/
public boolean getIgnoreTruncation() {
return ignoreTruncation;
}
@Override
public void setIgnoreTruncation(boolean flag) {
this.ignoreTruncation = flag;
}
/**
* Gets the EDNS information on outgoing messages.
*
* @return The current {@link OPTRecord} for EDNS or {@code null} if EDNS is disabled.
* @since 3.2
*/
public OPTRecord getEDNS() {
return queryOPT;
}
/**
* Sets the EDNS information on outgoing messages.
*
* @param optRecord the {@link OPTRecord} for EDNS options or null to disable EDNS.
* @see #setEDNS(int, int, int, List)
* @since 3.2
*/
public void setEDNS(OPTRecord optRecord) {
queryOPT = optRecord;
}
@Override
public void setEDNS(int version, int payloadSize, int flags, List<EDNSOption> options) {
switch (version) {
case -1:
queryOPT = null;
break;
case 0:
if (payloadSize == 0) {
payloadSize = DEFAULT_EDNS_PAYLOADSIZE;
}
queryOPT = new OPTRecord(payloadSize, 0, version, flags, options);
break;
default:
throw new IllegalArgumentException("invalid EDNS version - must be 0 or -1 to disable");
}
}
/**
* Get the TSIG key that messages will be signed with.
*
* @return the TSIG signature for outgoing messages or {@code null} if not specified.
* @since 3.2
*/
public TSIG getTSIGKey() {
return tsig;
}
@Override
public void setTSIGKey(TSIG key) {
tsig = key;
}
@Override
public void setTimeout(Duration timeout) {
timeoutValue = timeout;
}
@Override
public Duration getTimeout() {
return timeoutValue;
}
private Message parseMessage(byte[] b) throws WireParseException {
try {
return new Message(b);
} catch (IOException e) {
if (!(e instanceof WireParseException)) {
throw new WireParseException("Error parsing message", e);
}
throw (WireParseException) e;
}
}
private void verifyTSIG(Message query, Message response, byte[] b) {
if (tsig == null) {
return;
}
int error = tsig.verify(response, b, query.getGeneratedTSIG());
log.debug(
"TSIG verify on message id {}: {}", query.getHeader().getID(), Rcode.TSIGstring(error));
}
private void applyEDNS(Message query) {
if (queryOPT == null || query.getOPT() != null) {
return;
}
query.addRecord(queryOPT, Section.ADDITIONAL);
}
private int maxUDPSize(Message query) {
OPTRecord opt = query.getOPT();
if (opt == null) {
return DEFAULT_UDPSIZE;
} else {
return opt.getPayloadSize();
}
}
/**
* Asynchronously sends a message to a single server.
*
* @param query The query to send
* @return A future that completes when the response has arrived.
*/
@Override
public CompletionStage<Message> sendAsync(Message query) {
return sendAsync(query, ForkJoinPool.commonPool());
}
/**
* Asynchronously sends a message to a single server.
*
* @param query The query to send
* @param executor The service to use for async operations.
* @return A future that completes when the response has arrived.
*/
@Override
public CompletionStage<Message> sendAsync(Message query, Executor executor) {
if (query.getHeader().getOpcode() == Opcode.QUERY) {
Record question = query.getQuestion();
if (question != null && question.getType() == Type.AXFR) {
CompletableFuture<Message> f = new CompletableFuture<>();
CompletableFuture.runAsync(
() -> {
try {
f.complete(sendAXFR(query));
} catch (IOException e) {
f.completeExceptionally(e);
}
},
executor);
return f;
}
}
Message ednsTsigQuery = query.clone();
applyEDNS(ednsTsigQuery);
if (tsig != null) {
ednsTsigQuery.setTSIG(tsig, Rcode.NOERROR, null);
}
return sendAsync(ednsTsigQuery, useTCP, executor);
}
CompletableFuture<Message> sendAsync(Message query, boolean forceTcp, Executor executor) {
int qid = query.getHeader().getID();
byte[] out = query.toWire(Message.MAXLENGTH);
int udpSize = maxUDPSize(query);
boolean tcp = forceTcp || out.length > udpSize;
if (log.isTraceEnabled()) {
log.trace(
"Sending {}/{}, id={} to {}/{}:{}, query:\n{}",
query.getQuestion().getName(),
Type.string(query.getQuestion().getType()),
qid,
tcp ? "tcp" : "udp",
address.getAddress().getHostAddress(),
address.getPort(),
query);
} else if (log.isDebugEnabled()) {
log.debug(
"Sending {}/{}, id={} to {}/{}:{}",
query.getQuestion().getName(),
Type.string(query.getQuestion().getType()),
qid,
tcp ? "tcp" : "udp",
address.getAddress().getHostAddress(),
address.getPort());
}
CompletableFuture<byte[]> result;
if (tcp) {
result = NioTcpClient.sendrecv(localAddress, address, query, out, timeoutValue);
} else {
result = NioUdpClient.sendrecv(localAddress, address, query, out, udpSize, timeoutValue);
}
return result.thenComposeAsync(
in -> {
CompletableFuture<Message> f = new CompletableFuture<>();
// Check that the response is long enough.
if (in.length < Header.LENGTH) {
f.completeExceptionally(new WireParseException("invalid DNS header - too short"));
return f;
}
// Check that the response ID matches the query ID. We want
// to check this before actually parsing the message, so that
// if there's a malformed response that's not ours, it
// doesn't confuse us.
int id = ((in[0] & 0xFF) << 8) + (in[1] & 0xFF);
if (id != qid) {
f.completeExceptionally(
new WireParseException("invalid message id: expected " + qid + "; got id " + id));
return f;
}
Message response;
try {
response = parseMessage(in);
} catch (WireParseException e) {
f.completeExceptionally(e);
return f;
}
// validate name, class and type (rfc5452#section-9.1)
if (!query.getQuestion().getName().equals(response.getQuestion().getName())) {
f.completeExceptionally(
new WireParseException(
"invalid name in message: expected "
+ query.getQuestion().getName()
+ "; got "
+ response.getQuestion().getName()));
return f;
}
if (query.getQuestion().getDClass() != response.getQuestion().getDClass()) {
f.completeExceptionally(
new WireParseException(
"invalid class in message: expected "
+ DClass.string(query.getQuestion().getDClass())
+ "; got "
+ DClass.string(response.getQuestion().getDClass())));
return f;
}
if (query.getQuestion().getType() != response.getQuestion().getType()) {
f.completeExceptionally(
new WireParseException(
"invalid type in message: expected "
+ Type.string(query.getQuestion().getType())
+ "; got "
+ Type.string(response.getQuestion().getType())));
return f;
}
verifyTSIG(query, response, in);
if (!tcp && !ignoreTruncation && response.getHeader().getFlag(Flags.TC)) {
if (log.isTraceEnabled()) {
log.trace(
"Got truncated response for id {}, retrying via TCP, response:\n{}",
qid,
response);
} else {
log.debug("Got truncated response for id {}, retrying via TCP", qid);
}
return sendAsync(query, true, executor);
}
response.setResolver(this);
f.complete(response);
return f;
},
executor);
}
private Message sendAXFR(Message query) throws IOException {
Name qname = query.getQuestion().getName();
ZoneTransferIn xfrin = ZoneTransferIn.newAXFR(qname, address, tsig);
xfrin.setTimeout(timeoutValue);
xfrin.setLocalAddress(localAddress);
try {
xfrin.run();
} catch (ZoneTransferException e) {
throw new WireParseException(e.getMessage());
}
List<Record> records = xfrin.getAXFR();
Message response = new Message(query.getHeader().getID());
response.getHeader().setFlag(Flags.AA);
response.getHeader().setFlag(Flags.QR);
response.addRecord(query.getQuestion(), Section.QUESTION);
for (Record r : records) {
response.addRecord(r, Section.ANSWER);
}
return response;
}
@Override
public String toString() {
return "SimpleResolver [" + address + "]";
}
}