9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 import sun.security.util.HexDumpEncoder;
25
26 import java.io.IOException;
27 import java.net.DatagramPacket;
28 import java.net.DatagramSocket;
29 import java.nio.ByteBuffer;
30 import java.nio.file.Paths;
31 import java.util.ArrayList;
32 import java.util.Arrays;
33 import java.util.List;
34 import java.util.Scanner;
35 import java.util.regex.MatchResult;
36
37 /*
38 * A dummy DNS server.
39 *
40 * Loads a sequence of DNS messages from a capture file into its cache.
41 * It listens for DNS UDP requests, finds match request in cache and sends the
42 * corresponding DNS responses.
43 *
44 * The capture file contains an DNS protocol exchange in the hexadecimal
45 * dump format emitted by HexDumpEncoder:
46 *
47 * xxxx: 00 11 22 33 44 55 66 77 88 99 aa bb cc dd ee ff ................
48 *
49 * Typically, DNS protocol exchange is generated by DNSTracer who captures
50 * communication messages between DNS application program and real DNS server
51 */
52 public class DNSServer implements Runnable {
53
54 public class Pair<F, S> {
55 private F first;
56 private S second;
57
58 public Pair(F first, S second) {
59 this.first = first;
60 this.second = second;
61 }
62
63 public void setFirst(F first) {
64 this.first = first;
65 }
66
67 public void setSecond(S second) {
68 this.second = second;
69 }
70
71 public F getFirst() {
72 return first;
73 }
74
75 public S getSecond() {
76 return second;
77 }
78 }
79
80 public static final int DNS_HEADER_SIZE = 12;
81 public static final int DNS_PACKET_SIZE = 512;
82
83 static HexDumpEncoder encoder = new HexDumpEncoder();
84
85 private DatagramSocket socket;
86 private String filename;
87 private boolean loop;
88 private final List<Pair<byte[], byte[]>> cache = new ArrayList<>();
89 private ByteBuffer reqBuffer = ByteBuffer.allocate(DNS_PACKET_SIZE);
90
91 public DNSServer(DatagramSocket socket, String filename) {
92 this(socket, filename, false);
93 }
94
95 public DNSServer(DatagramSocket socket, String filename, boolean loop) {
96 this.socket = socket;
97 this.filename = filename;
98 this.loop = loop;
99 }
100
101 public void run() {
102 try {
103 System.out.println(
104 "DNSServer: Loading DNS cache data from : " + filename);
105 loadCaptureFile(filename);
106
107 System.out.println(
108 "DNSServer: listening on port " + socket.getLocalPort());
109
110 System.out.println("DNSServer: loop playback: " + loop);
111
112 int playbackIndex = 0;
113
114 while (playbackIndex < cache.size()) {
115 DatagramPacket reqPacket = new DatagramPacket(reqBuffer.array(),
116 reqBuffer.array().length);
117 socket.receive(reqPacket);
118
119 System.out.println(
120 "DNSServer: received query message from " + reqPacket
121 .getSocketAddress());
122
123 if (!verifyRequestMsg(reqPacket, playbackIndex)) {
124 throw new RuntimeException(
125 "DNSServer: Error: Failed to verify DNS request. "
126 + "Not identical request message : \n"
127 + encoder.encodeBuffer(
128 Arrays.copyOf(reqPacket.getData(),
129 reqPacket.getLength())));
130 }
131
132 byte[] payload = generateResponsePayload(reqPacket,
133 playbackIndex);
134 socket.send(new DatagramPacket(payload, payload.length,
135 reqPacket.getSocketAddress()));
136 System.out.println(
137 "DNSServer: send response message to " + reqPacket
138 .getSocketAddress());
139
140 playbackIndex++;
141 if (loop && playbackIndex >= cache.size()) {
142 playbackIndex = 0;
143 }
144 }
145
146 System.out.println(
147 "DNSServer: Done for all cached messages playback");
148 } catch (Exception e) {
149 System.err.println("DNSServer: Error: " + e);
150 }
151 }
152
153 /*
154 * Load a capture file containing an DNS protocol exchange in the
155 * hexadecimal dump format emitted by sun.misc.HexDumpEncoder:
156 *
157 * xxxx: 00 11 22 33 44 55 66 77 88 99 aa bb cc dd ee ff ................
158 */
159 private void loadCaptureFile(String filename) throws IOException {
160 StringBuilder hexString = new StringBuilder();
161 String pattern = "(....): (..) (..) (..) (..) (..) (..) (..) (..) "
162 + "(..) (..) (..) (..) (..) (..) (..) (..).*";
163
164 try (Scanner fileScanner = new Scanner(Paths.get(filename))) {
165 while (fileScanner.hasNextLine()) {
166
167 try (Scanner lineScanner = new Scanner(
168 fileScanner.nextLine())) {
169 if (lineScanner.findInLine(pattern) == null) {
170 continue;
171 }
282 }
283
284 out[i / 2] = (byte) (h * 16 + l);
285 }
286
287 return out;
288 }
289
290 private static int hexToBin(char ch) {
291 if ('0' <= ch && ch <= '9') {
292 return ch - '0';
293 }
294 if ('A' <= ch && ch <= 'F') {
295 return ch - 'A' + 10;
296 }
297 if ('a' <= ch && ch <= 'f') {
298 return ch - 'a' + 10;
299 }
300 return -1;
301 }
302 }
|
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 import sun.security.util.HexDumpEncoder;
25
26 import java.io.IOException;
27 import java.net.DatagramPacket;
28 import java.net.DatagramSocket;
29 import java.net.InetAddress;
30 import java.net.SocketException;
31 import java.nio.ByteBuffer;
32 import java.nio.file.Paths;
33 import java.util.ArrayList;
34 import java.util.Arrays;
35 import java.util.List;
36 import java.util.Scanner;
37 import java.util.regex.MatchResult;
38
39 /*
40 * A dummy DNS server.
41 *
42 * Loads a sequence of DNS messages from a capture file into its cache.
43 * It listens for DNS UDP requests, finds match request in cache and sends the
44 * corresponding DNS responses.
45 *
46 * The capture file contains an DNS protocol exchange in the hexadecimal
47 * dump format emitted by HexDumpEncoder:
48 *
49 * xxxx: 00 11 22 33 44 55 66 77 88 99 aa bb cc dd ee ff ................
50 *
51 * Typically, DNS protocol exchange is generated by DNSTracer who captures
52 * communication messages between DNS application program and real DNS server
53 */
54 public class DNSServer extends Thread implements Server {
55
56 public class Pair<F, S> {
57 private F first;
58 private S second;
59
60 public Pair(F first, S second) {
61 this.first = first;
62 this.second = second;
63 }
64
65 public void setFirst(F first) {
66 this.first = first;
67 }
68
69 public void setSecond(S second) {
70 this.second = second;
71 }
72
73 public F getFirst() {
74 return first;
75 }
76
77 public S getSecond() {
78 return second;
79 }
80 }
81
82 public static final int DNS_HEADER_SIZE = 12;
83 public static final int DNS_PACKET_SIZE = 512;
84
85 static HexDumpEncoder encoder = new HexDumpEncoder();
86
87 private DatagramSocket socket;
88 private String filename;
89 private boolean loop;
90 private final List<Pair<byte[], byte[]>> cache = new ArrayList<>();
91 private ByteBuffer reqBuffer = ByteBuffer.allocate(DNS_PACKET_SIZE);
92 private volatile boolean isRunning;
93
94 public DNSServer(String filename) throws SocketException {
95 this(filename, false);
96 }
97
98 public DNSServer(String filename, boolean loop) throws SocketException {
99 this.socket = new DatagramSocket(0, InetAddress.getLoopbackAddress());
100 this.filename = filename;
101 this.loop = loop;
102 }
103
104 public void run() {
105 try {
106 isRunning = true;
107 System.out.println(
108 "DNSServer: Loading DNS cache data from : " + filename);
109 loadCaptureFile(filename);
110
111 System.out.println(
112 "DNSServer: listening on port " + socket.getLocalPort());
113
114 System.out.println("DNSServer: loop playback: " + loop);
115
116 int playbackIndex = 0;
117
118 while (playbackIndex < cache.size()) {
119 DatagramPacket reqPacket = receiveQuery();
120
121 if (!verifyRequestMsg(reqPacket, playbackIndex)) {
122 if (playbackIndex > 0 && verifyRequestMsg(reqPacket,
123 playbackIndex - 1)) {
124 System.out.println(
125 "DNSServer: received retry query, resend");
126 playbackIndex--;
127 } else {
128 throw new RuntimeException(
129 "DNSServer: Error: Failed to verify DNS request. "
130 + "Not identical request message : \n"
131 + encoder.encodeBuffer(
132 Arrays.copyOf(reqPacket.getData(),
133 reqPacket.getLength())));
134 }
135 }
136
137 sendResponse(reqPacket, playbackIndex);
138
139 playbackIndex++;
140 if (loop && playbackIndex >= cache.size()) {
141 playbackIndex = 0;
142 }
143 }
144
145 System.out.println(
146 "DNSServer: Done for all cached messages playback");
147
148 System.out.println(
149 "DNSServer: Still listening for possible retry query");
150 while (true) {
151 DatagramPacket reqPacket = receiveQuery();
152
153 // here we only handle the retry query for last one
154 if (!verifyRequestMsg(reqPacket, playbackIndex - 1)) {
155 throw new RuntimeException(
156 "DNSServer: Error: Failed to verify DNS request. "
157 + "Not identical request message : \n"
158 + encoder.encodeBuffer(
159 Arrays.copyOf(reqPacket.getData(),
160 reqPacket.getLength())));
161 }
162
163 sendResponse(reqPacket, playbackIndex - 1);
164 }
165 } catch (Exception e) {
166 if (isRunning) {
167 System.err.println("DNSServer: Error: " + e);
168 e.printStackTrace();
169 } else {
170 System.out.println("DNSServer: Exit");
171 }
172 }
173 }
174
175 private DatagramPacket receiveQuery() throws IOException {
176 DatagramPacket reqPacket = new DatagramPacket(reqBuffer.array(),
177 reqBuffer.array().length);
178 socket.receive(reqPacket);
179
180 System.out.println("DNSServer: received query message from " + reqPacket
181 .getSocketAddress());
182
183 return reqPacket;
184 }
185
186 private void sendResponse(DatagramPacket reqPacket, int playbackIndex)
187 throws IOException {
188 byte[] payload = generateResponsePayload(reqPacket, playbackIndex);
189 socket.send(new DatagramPacket(payload, payload.length,
190 reqPacket.getSocketAddress()));
191 System.out.println("DNSServer: send response message to " + reqPacket
192 .getSocketAddress());
193 }
194
195 /*
196 * Load a capture file containing an DNS protocol exchange in the
197 * hexadecimal dump format emitted by sun.misc.HexDumpEncoder:
198 *
199 * xxxx: 00 11 22 33 44 55 66 77 88 99 aa bb cc dd ee ff ................
200 */
201 private void loadCaptureFile(String filename) throws IOException {
202 StringBuilder hexString = new StringBuilder();
203 String pattern = "(....): (..) (..) (..) (..) (..) (..) (..) (..) "
204 + "(..) (..) (..) (..) (..) (..) (..) (..).*";
205
206 try (Scanner fileScanner = new Scanner(Paths.get(filename))) {
207 while (fileScanner.hasNextLine()) {
208
209 try (Scanner lineScanner = new Scanner(
210 fileScanner.nextLine())) {
211 if (lineScanner.findInLine(pattern) == null) {
212 continue;
213 }
324 }
325
326 out[i / 2] = (byte) (h * 16 + l);
327 }
328
329 return out;
330 }
331
332 private static int hexToBin(char ch) {
333 if ('0' <= ch && ch <= '9') {
334 return ch - '0';
335 }
336 if ('A' <= ch && ch <= 'F') {
337 return ch - 'A' + 10;
338 }
339 if ('a' <= ch && ch <= 'f') {
340 return ch - 'a' + 10;
341 }
342 return -1;
343 }
344
345 @Override public void stopServer() {
346 isRunning = false;
347 if (socket != null) {
348 try {
349 socket.close();
350 } catch (Exception e) {
351 // ignore
352 }
353 }
354 }
355
356 @Override public int getPort() {
357 if (socket != null) {
358 return socket.getLocalPort();
359 } else {
360 return -1;
361 }
362 }
363 }
|