test/jdk/com/sun/jndi/dns/lib/DNSServer.java - platform/libcore - Git at Google

 /*
  * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */

 import sun.security.util.HexDumpEncoder;

 import java.io.IOException;
 import java.net.DatagramPacket;
 import java.net.DatagramSocket;
 import java.net.InetAddress;
 import java.net.SocketException;
 import java.nio.ByteBuffer;
 import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Scanner;
 import java.util.regex.MatchResult;

 /*
  * A dummy DNS server.
  *
  * Loads a sequence of DNS messages from a capture file into its cache.
  * It listens for DNS UDP requests, finds match request in cache and sends the
  * corresponding DNS responses.
  *
  * The capture file contains an DNS protocol exchange in the hexadecimal
  * dump format emitted by HexDumpEncoder:
  *
  * xxxx: 00 11 22 33 44 55 66 77   88 99 aa bb cc dd ee ff  ................
  *
  * Typically, DNS protocol exchange is generated by DNSTracer who captures
  * communication messages between DNS application program and real DNS server
  */
 public class DNSServer extends Thread implements Server {

     public class Pair<F, S> {
         private F first;
         private S second;

         public Pair(F first, S second) {
             this.first = first;
             this.second = second;
         }

         public void setFirst(F first) {
             this.first = first;
         }

         public void setSecond(S second) {
             this.second = second;
         }

         public F getFirst() {
             return first;
         }

         public S getSecond() {
             return second;
         }
     }

     public static final int DNS_HEADER_SIZE = 12;
     public static final int DNS_PACKET_SIZE = 512;

     static HexDumpEncoder encoder = new HexDumpEncoder();

     private DatagramSocket socket;
     private String filename;
     private boolean loop;
     private final List<Pair<byte[], byte[]>> cache = new ArrayList<>();
     private ByteBuffer reqBuffer = ByteBuffer.allocate(DNS_PACKET_SIZE);
     private volatile boolean isRunning;

     public DNSServer(String filename) throws SocketException {
         this(filename, false);
     }

     public DNSServer(String filename, boolean loop) throws SocketException {
         this.socket = new DatagramSocket(0, InetAddress.getLoopbackAddress());
         this.filename = filename;
         this.loop = loop;
     }

     public void run() {
         try {
             isRunning = true;
             System.out.println(
                     "DNSServer: Loading DNS cache data from : " + filename);
             loadCaptureFile(filename);

             System.out.println(
                     "DNSServer: listening on port " + socket.getLocalPort());

             System.out.println("DNSServer: loop playback: " + loop);

             int playbackIndex = 0;

             while (playbackIndex < cache.size()) {
                 DatagramPacket reqPacket = receiveQuery();

                 if (!verifyRequestMsg(reqPacket, playbackIndex)) {
                     if (playbackIndex > 0 && verifyRequestMsg(reqPacket,
                             playbackIndex - 1)) {
                         System.out.println(
                                 "DNSServer: received retry query, resend");
                         playbackIndex--;
                     } else {
                         throw new RuntimeException(
                                 "DNSServer: Error: Failed to verify DNS request. "
                                         + "Not identical request message : \n"
                                         + encoder.encodeBuffer(
                                         Arrays.copyOf(reqPacket.getData(),
                                                 reqPacket.getLength())));
                     }
                 }

                 sendResponse(reqPacket, playbackIndex);

                 playbackIndex++;
                 if (loop && playbackIndex >= cache.size()) {
                     playbackIndex = 0;
                 }
             }

             System.out.println(
                     "DNSServer: Done for all cached messages playback");

             System.out.println(
                     "DNSServer: Still listening for possible retry query");
             while (true) {
                 DatagramPacket reqPacket = receiveQuery();

                 // here we only handle the retry query for last one
                 if (!verifyRequestMsg(reqPacket, playbackIndex - 1)) {
                     throw new RuntimeException(
                             "DNSServer: Error: Failed to verify DNS request. "
                                     + "Not identical request message : \n"
                                     + encoder.encodeBuffer(
                                     Arrays.copyOf(reqPacket.getData(),
                                             reqPacket.getLength())));
                 }

                 sendResponse(reqPacket, playbackIndex - 1);
             }
         } catch (Exception e) {
             if (isRunning) {
                 System.err.println("DNSServer: Error: " + e);
                 e.printStackTrace();
             } else {
                 System.out.println("DNSServer: Exit");
             }
         }
     }

     private DatagramPacket receiveQuery() throws IOException {
         DatagramPacket reqPacket = new DatagramPacket(reqBuffer.array(),
                 reqBuffer.array().length);
         socket.receive(reqPacket);

         System.out.println("DNSServer: received query message from " + reqPacket
                 .getSocketAddress());

         return reqPacket;
     }

     private void sendResponse(DatagramPacket reqPacket, int playbackIndex)
             throws IOException {
         byte[] payload = generateResponsePayload(reqPacket, playbackIndex);
         socket.send(new DatagramPacket(payload, payload.length,
                 reqPacket.getSocketAddress()));
         System.out.println("DNSServer: send response message to " + reqPacket
                 .getSocketAddress());
     }

     /*
      * Load a capture file containing an DNS protocol exchange in the
      * hexadecimal dump format emitted by sun.misc.HexDumpEncoder:
      *
      * xxxx: 00 11 22 33 44 55 66 77   88 99 aa bb cc dd ee ff  ................
      */
     private void loadCaptureFile(String filename) throws IOException {
         StringBuilder hexString = new StringBuilder();
         String pattern = "(....): (..) (..) (..) (..) (..) (..) (..) (..)   "
                 + "(..) (..) (..) (..) (..) (..) (..) (..).*";

         try (Scanner fileScanner = new Scanner(Paths.get(filename))) {
             while (fileScanner.hasNextLine()) {

                 try (Scanner lineScanner = new Scanner(
                         fileScanner.nextLine())) {
                     if (lineScanner.findInLine(pattern) == null) {
                         continue;
                     }
                     MatchResult result = lineScanner.match();
                     for (int i = 1; i <= result.groupCount(); i++) {
                         String digits = result.group(i);
                         if (digits.length() == 4) {
                             if (digits.equals("0000")) { // start-of-message
                                 if (hexString.length() > 0) {
                                     addToCache(hexString.toString());
                                     hexString.delete(0, hexString.length());
                                 }
                             }
                             continue;
                         } else if (digits.equals("  ")) { // short message
                             continue;
                         }
                         hexString.append(digits);
                     }
                 }
             }
         }
         addToCache(hexString.toString());
     }

     /*
      * Add an DNS encoding to the cache (by request message key).
      */
     private void addToCache(String hexString) {
         byte[] encoding = parseHexBinary(hexString);
         if (encoding.length < DNS_HEADER_SIZE) {
             throw new RuntimeException("Invalid DNS message : " + hexString);
         }

         if (getQR(encoding) == 0) {
             // a query message, create entry in cache
             cache.add(new Pair<>(encoding, null));
             System.out.println(
                     "    adding DNS query message with ID " + getID(encoding)
                             + " to the cache");
         } else {
             // a response message, attach it to the query entry
             if (!cache.isEmpty() && (getID(getLatestCacheEntry().getFirst())
                     == getID(encoding))) {
                 getLatestCacheEntry().setSecond(encoding);
                 System.out.println(
                         "    adding DNS response message associated to ID "
                                 + getID(encoding) + " in the cache");
             } else {
                 throw new RuntimeException(
                         "Invalid DNS message : " + hexString);
             }
         }
     }

     /*
      * ID: A 16 bit identifier assigned by the program that generates any
      * kind of query. This identifier is copied the corresponding reply and
      * can be used by the requester to match up replies to outstanding queries.
      */
     private static int getID(byte[] encoding) {
         return ByteBuffer.wrap(encoding, 0, 2).getShort();
     }

     /*
      * QR: A one bit field that specifies whether this message is
      * a query (0), or a response (1) after ID
      */
     private static int getQR(byte[] encoding) {
         return encoding[2] & (0x01 << 7);
     }

     private Pair<byte[], byte[]> getLatestCacheEntry() {
         return cache.get(cache.size() - 1);
     }

     private boolean verifyRequestMsg(DatagramPacket packet, int playbackIndex) {
         byte[] cachedRequest = cache.get(playbackIndex).getFirst();
         return Arrays.equals(Arrays
                         .copyOfRange(packet.getData(), 2, packet.getLength()),
                 Arrays.copyOfRange(cachedRequest, 2, cachedRequest.length));
     }

     private byte[] generateResponsePayload(DatagramPacket packet,
             int playbackIndex) {
         byte[] resMsg = cache.get(playbackIndex).getSecond();
         byte[] payload = Arrays.copyOf(resMsg, resMsg.length);

         // replace the ID with same with real request
         payload[0] = packet.getData()[0];
         payload[1] = packet.getData()[1];

         return payload;
     }

     public static byte[] parseHexBinary(String s) {

         final int len = s.length();

         // "111" is not a valid hex encoding.
         if (len % 2 != 0) {
             throw new IllegalArgumentException(
                     "hexBinary needs to be even-length: " + s);
         }

         byte[] out = new byte[len / 2];

         for (int i = 0; i < len; i += 2) {
             int h = hexToBin(s.charAt(i));
             int l = hexToBin(s.charAt(i + 1));
             if (h == -1 || l == -1) {
                 throw new IllegalArgumentException(
                         "contains illegal character for hexBinary: " + s);
             }

             out[i / 2] = (byte) (h * 16 + l);
         }

         return out;
     }

     private static int hexToBin(char ch) {
         if ('0' <= ch && ch <= '9') {
             return ch - '0';
         }
         if ('A' <= ch && ch <= 'F') {
             return ch - 'A' + 10;
         }
         if ('a' <= ch && ch <= 'f') {
             return ch - 'a' + 10;
         }
         return -1;
     }

     @Override public void stopServer() {
         isRunning = false;
         if (socket != null) {
             try {
                 socket.close();
             } catch (Exception e) {
                 // ignore
             }
         }
     }

     @Override public int getPort() {
         if (socket != null) {
             return socket.getLocalPort();
         } else {
             return -1;
         }
     }
 }
	/*
	* Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	import sun.security.util.HexDumpEncoder;

	import java.io.IOException;
	import java.net.DatagramPacket;
	import java.net.DatagramSocket;
	import java.net.InetAddress;
	import java.net.SocketException;
	import java.nio.ByteBuffer;
	import java.nio.file.Paths;
	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.List;
	import java.util.Scanner;
	import java.util.regex.MatchResult;

	/*
	* A dummy DNS server.
	*
	* Loads a sequence of DNS messages from a capture file into its cache.
	* It listens for DNS UDP requests, finds match request in cache and sends the
	* corresponding DNS responses.
	*
	* The capture file contains an DNS protocol exchange in the hexadecimal
	* dump format emitted by HexDumpEncoder:
	*
	* xxxx: 00 11 22 33 44 55 66 77 88 99 aa bb cc dd ee ff ................
	*
	* Typically, DNS protocol exchange is generated by DNSTracer who captures
	* communication messages between DNS application program and real DNS server
	*/
	public class DNSServer extends Thread implements Server {

	public class Pair<F, S> {
	private F first;
	private S second;

	public Pair(F first, S second) {
	this.first = first;
	this.second = second;
	}

	public void setFirst(F first) {
	this.first = first;
	}

	public void setSecond(S second) {
	this.second = second;
	}

	public F getFirst() {
	return first;
	}

	public S getSecond() {
	return second;
	}
	}

	public static final int DNS_HEADER_SIZE = 12;
	public static final int DNS_PACKET_SIZE = 512;

	static HexDumpEncoder encoder = new HexDumpEncoder();

	private DatagramSocket socket;
	private String filename;
	private boolean loop;
	private final List<Pair<byte[], byte[]>> cache = new ArrayList<>();
	private ByteBuffer reqBuffer = ByteBuffer.allocate(DNS_PACKET_SIZE);
	private volatile boolean isRunning;

	public DNSServer(String filename) throws SocketException {
	this(filename, false);
	}

	public DNSServer(String filename, boolean loop) throws SocketException {
	this.socket = new DatagramSocket(0, InetAddress.getLoopbackAddress());
	this.filename = filename;
	this.loop = loop;
	}

	public void run() {
	try {
	isRunning = true;
	System.out.println(
	"DNSServer: Loading DNS cache data from : " + filename);
	loadCaptureFile(filename);

	System.out.println(
	"DNSServer: listening on port " + socket.getLocalPort());

	System.out.println("DNSServer: loop playback: " + loop);

	int playbackIndex = 0;

	while (playbackIndex < cache.size()) {
	DatagramPacket reqPacket = receiveQuery();

	if (!verifyRequestMsg(reqPacket, playbackIndex)) {
	if (playbackIndex > 0 && verifyRequestMsg(reqPacket,
	playbackIndex - 1)) {
	System.out.println(
	"DNSServer: received retry query, resend");
	playbackIndex--;
	} else {
	throw new RuntimeException(
	"DNSServer: Error: Failed to verify DNS request. "
	+ "Not identical request message : \n"
	+ encoder.encodeBuffer(
	Arrays.copyOf(reqPacket.getData(),
	reqPacket.getLength())));
	}
	}

	sendResponse(reqPacket, playbackIndex);

	playbackIndex++;
	if (loop && playbackIndex >= cache.size()) {
	playbackIndex = 0;
	}
	}

	System.out.println(
	"DNSServer: Done for all cached messages playback");

	System.out.println(
	"DNSServer: Still listening for possible retry query");
	while (true) {
	DatagramPacket reqPacket = receiveQuery();

	// here we only handle the retry query for last one
	if (!verifyRequestMsg(reqPacket, playbackIndex - 1)) {
	throw new RuntimeException(
	"DNSServer: Error: Failed to verify DNS request. "
	+ "Not identical request message : \n"
	+ encoder.encodeBuffer(
	Arrays.copyOf(reqPacket.getData(),
	reqPacket.getLength())));
	}

	sendResponse(reqPacket, playbackIndex - 1);
	}
	} catch (Exception e) {
	if (isRunning) {
	System.err.println("DNSServer: Error: " + e);
	e.printStackTrace();
	} else {
	System.out.println("DNSServer: Exit");
	}
	}
	}

	private DatagramPacket receiveQuery() throws IOException {
	DatagramPacket reqPacket = new DatagramPacket(reqBuffer.array(),
	reqBuffer.array().length);
	socket.receive(reqPacket);

	System.out.println("DNSServer: received query message from " + reqPacket
	.getSocketAddress());

	return reqPacket;
	}

	private void sendResponse(DatagramPacket reqPacket, int playbackIndex)
	throws IOException {
	byte[] payload = generateResponsePayload(reqPacket, playbackIndex);
	socket.send(new DatagramPacket(payload, payload.length,
	reqPacket.getSocketAddress()));
	System.out.println("DNSServer: send response message to " + reqPacket
	.getSocketAddress());
	}

	/*
	* Load a capture file containing an DNS protocol exchange in the
	* hexadecimal dump format emitted by sun.misc.HexDumpEncoder:
	*
	* xxxx: 00 11 22 33 44 55 66 77 88 99 aa bb cc dd ee ff ................
	*/
	private void loadCaptureFile(String filename) throws IOException {
	StringBuilder hexString = new StringBuilder();
	String pattern = "(....): (..) (..) (..) (..) (..) (..) (..) (..) "
	+ "(..) (..) (..) (..) (..) (..) (..) (..).*";

	try (Scanner fileScanner = new Scanner(Paths.get(filename))) {
	while (fileScanner.hasNextLine()) {

	try (Scanner lineScanner = new Scanner(
	fileScanner.nextLine())) {
	if (lineScanner.findInLine(pattern) == null) {
	continue;
	}
	MatchResult result = lineScanner.match();
	for (int i = 1; i <= result.groupCount(); i++) {
	String digits = result.group(i);
	if (digits.length() == 4) {
	if (digits.equals("0000")) { // start-of-message
	if (hexString.length() > 0) {
	addToCache(hexString.toString());
	hexString.delete(0, hexString.length());
	}
	}
	continue;
	} else if (digits.equals(" ")) { // short message
	continue;
	}
	hexString.append(digits);
	}
	}
	}
	}
	addToCache(hexString.toString());
	}

	/*
	* Add an DNS encoding to the cache (by request message key).
	*/
	private void addToCache(String hexString) {
	byte[] encoding = parseHexBinary(hexString);
	if (encoding.length < DNS_HEADER_SIZE) {
	throw new RuntimeException("Invalid DNS message : " + hexString);
	}

	if (getQR(encoding) == 0) {
	// a query message, create entry in cache
	cache.add(new Pair<>(encoding, null));
	System.out.println(
	" adding DNS query message with ID " + getID(encoding)
	+ " to the cache");
	} else {
	// a response message, attach it to the query entry
	if (!cache.isEmpty() && (getID(getLatestCacheEntry().getFirst())
	== getID(encoding))) {
	getLatestCacheEntry().setSecond(encoding);
	System.out.println(
	" adding DNS response message associated to ID "
	+ getID(encoding) + " in the cache");
	} else {
	throw new RuntimeException(
	"Invalid DNS message : " + hexString);
	}
	}
	}

	/*
	* ID: A 16 bit identifier assigned by the program that generates any
	* kind of query. This identifier is copied the corresponding reply and
	* can be used by the requester to match up replies to outstanding queries.
	*/
	private static int getID(byte[] encoding) {
	return ByteBuffer.wrap(encoding, 0, 2).getShort();
	}

	/*
	* QR: A one bit field that specifies whether this message is
	* a query (0), or a response (1) after ID
	*/
	private static int getQR(byte[] encoding) {
	return encoding[2] & (0x01 << 7);
	}

	private Pair<byte[], byte[]> getLatestCacheEntry() {
	return cache.get(cache.size() - 1);
	}

	private boolean verifyRequestMsg(DatagramPacket packet, int playbackIndex) {
	byte[] cachedRequest = cache.get(playbackIndex).getFirst();
	return Arrays.equals(Arrays
	.copyOfRange(packet.getData(), 2, packet.getLength()),
	Arrays.copyOfRange(cachedRequest, 2, cachedRequest.length));
	}

	private byte[] generateResponsePayload(DatagramPacket packet,
	int playbackIndex) {
	byte[] resMsg = cache.get(playbackIndex).getSecond();
	byte[] payload = Arrays.copyOf(resMsg, resMsg.length);

	// replace the ID with same with real request
	payload[0] = packet.getData()[0];
	payload[1] = packet.getData()[1];

	return payload;
	}

	public static byte[] parseHexBinary(String s) {

	final int len = s.length();

	// "111" is not a valid hex encoding.
	if (len % 2 != 0) {
	throw new IllegalArgumentException(
	"hexBinary needs to be even-length: " + s);
	}

	byte[] out = new byte[len / 2];

	for (int i = 0; i < len; i += 2) {
	int h = hexToBin(s.charAt(i));
	int l = hexToBin(s.charAt(i + 1));
	if (h == -1 \|\| l == -1) {
	throw new IllegalArgumentException(
	"contains illegal character for hexBinary: " + s);
	}

	out[i / 2] = (byte) (h * 16 + l);
	}

	return out;
	}

	private static int hexToBin(char ch) {
	if ('0' <= ch && ch <= '9') {
	return ch - '0';
	}
	if ('A' <= ch && ch <= 'F') {
	return ch - 'A' + 10;
	}
	if ('a' <= ch && ch <= 'f') {
	return ch - 'a' + 10;
	}
	return -1;
	}

	@Override public void stopServer() {
	isRunning = false;
	if (socket != null) {
	try {
	socket.close();
	} catch (Exception e) {
	// ignore
	}
	}
	}

	@Override public int getPort() {
	if (socket != null) {
	return socket.getLocalPort();
	} else {
	return -1;
	}
	}
	}