NIO SSL Server and HTML5 Secure WebSockets

Hi everyone,

this post relates to the "very old" topic http://www.java-gaming.org/topics/nio-ssl-server/21984/view started by Riven.

I'm trying to implement HTML 5 "Secure WebSocket" (TLS/SSL) connections with my existing Java Server using NIO channels. Up to now I have successfully implemented unsecure "WebSocket" connections.

Javascript example code for unsecure WebSocket connections

1	var connection = new WebSocket('ws://192.168.166.150:9005');

Javascript example code for secure WebSocket connections

1	var connection = new WebSocket('wss://192.168.166.150:9005');

Javascript Code is executed in Google Chrome or Firefox.

Here's my server side JAVA code called on incoming data

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57

private void read(SelectionKey key) throws IOException
   {
      SocketChannel socketChannel = (SocketChannel) key.channel();

      // Clear out our read buffer so it's ready for new data
      this.readBuffer.clear();

      // Attempt to read off the channel
      int numRead;
      try
      {
         numRead = socketChannel.read(this.readBuffer);
      }
      catch(IOException e)
      {
         // The remote forcibly closed the connection, cancel
         // the selection key and close the channel.
         this.checkRemoveClient(key);
         return;
      }

      if(numRead == -1)
      {
         // Remote entity shut the socket down cleanly. Do the
         // same from our end and cancel the channel.
         this.checkRemoveClient(key);
         return;
      }
      else
      {
         // Hand the data off to our clientRequestHandler thread
         Client client = (Client)this.clientList.get(socketChannel.hashCode());
         
         byte[] rawData;
         if(this.isSSLEnabled())
         {
            this.writeLogMessage("PLAIN DATA read ["+(new String(this.readBuffer.array()))+"]");

             this.readBuffer.flip();

             ByteBuffer copy = ByteBuffer.allocateDirect(numRead);
             copy.put(this.readBuffer);
             copy.flip();

             ClientRequestHandlerSSL crhSSL = new ClientRequestHandlerSSL(this, client, sslContext.createSSLEngine(), this.readBuffer.capacity());
             crhSSL.receive(copy);
         }
         else
         {
            rawData = this.readBuffer.array();
            ClientRequestHandler crh = new ClientRequestHandler(this, client, rawData, numRead);
            crh.run();
         }
         //
         //this.clientRequestHandler.processData(this, client, this.readBuffer.array(), numRead);
      }
   }

I used the JAVA code example from Riven and adapted it to my existing code architecture for handling SSL data coming over my socket channel:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;

import javax.net.ssl.SSLEngine;
import javax.net.ssl.SSLEngineResult;
import javax.net.ssl.SSLException;
import javax.net.ssl.SSLSession;

public class ClientRequestHandlerSSL implements Runnable
{
   private ByteBuffer wrapSrc, unwrapSrc;
   private ByteBuffer wrapDst, unwrapDst;

   private SSLEngine  engine;
   private Executor   ioWorker, taskWorkers;
   
   private MyServer serverHandle;
   private SocketChannel socketChannel;
   private Client client;

   /**
    * RECEIVE
    * @param serverHandle
    * @param client
    * @param engine
    * @param bufferSize
    * @param ioWorker
    * @param taskWorkers
    */
   public ClientRequestHandlerSSL(MyServer serverHandle, Client client, SSLEngine engine, int bufferSize)
   {
      System.out.println("construct read");
      this.serverHandle = serverHandle;
      this.socketChannel = null;
      this.client = client;
   System.out.println("Allocate RCV Buffer size: ["+bufferSize+"]");
      this.wrapSrc = ByteBuffer.allocateDirect(bufferSize);
      this.wrapDst = ByteBuffer.allocateDirect(bufferSize);

      this.unwrapSrc = ByteBuffer.allocateDirect(bufferSize);
      this.unwrapDst = ByteBuffer.allocateDirect(bufferSize);

      this.unwrapSrc.limit(0);

      this.engine = engine;
      this.engine.setUseClientMode(false);
      this.engine.setNeedClientAuth(false);
      this.engine.setWantClientAuth(false);
      try
      {
         this.engine.beginHandshake();
      }
      catch(SSLException e) {
         this.serverHandle.writeLogMessage("Can not begin handshake ["+e.getMessage()+"]");
      }
      
      this.ioWorker = Executors.newSingleThreadExecutor();
      this.taskWorkers = Executors.newFixedThreadPool(4);

      this.ioWorker.execute(this);
   }
   
   /**
    * SEND
    * 
    * @param serverHandle
    * @param socketChannel
    * @param engine
    * @param bufferSize
    * @param ioWorker
    * @param taskWorkers
    */
   public ClientRequestHandlerSSL(MyServer serverHandle, SocketChannel socketChannel, SSLEngine engine, int bufferSize)
   {
      System.out.println("construct send");
      this.serverHandle = serverHandle;
      this.socketChannel = socketChannel;
      this.client = null;
System.out.println("Allocate SND Buffer size: ["+bufferSize+"]");
      this.wrapSrc = ByteBuffer.allocateDirect(bufferSize);
      this.wrapDst = ByteBuffer.allocateDirect(bufferSize);

      this.unwrapSrc = ByteBuffer.allocateDirect(bufferSize);
      this.unwrapDst = ByteBuffer.allocateDirect(bufferSize);

      this.unwrapSrc.limit(0);

      this.engine = engine;
      this.engine.setUseClientMode(false);
      this.engine.setNeedClientAuth(false);
      this.engine.setWantClientAuth(false);
      
      try
      {
         this.engine.beginHandshake();
      }
      catch(SSLException e) {
         this.serverHandle.writeLogMessage("Can not begin handshake ["+e.getMessage()+"]");
      }
      
      this.ioWorker = Executors.newSingleThreadExecutor();
      this.taskWorkers = Executors.newFixedThreadPool(4);

      this.ioWorker.execute(this);
   }

   public void handleSendData(ByteBuffer decrypted)
   {
      try
      {
         this.serverHandle.writeLogMessage("SSL data send ["+(new String(decrypted.array()))+"]");
         this.socketChannel.write(decrypted);
      }
      catch (IOException e)
      {
         e.printStackTrace();
      }
   }

   public void handleReceivedData(ByteBuffer encrypted)
   {
      byte[] dst = new byte[encrypted.remaining()];
      encrypted.get(dst);
       

      this.serverHandle.writeLogMessage("SSL data received ["+(new String(dst))+"]");
      this.serverHandle.writeLogMessage("=======================================================================================");
       this.serverHandle.writeLogMessage("SSL data received decoded ["+(MessageDeEncoder.decodeWebSocketFrame(dst))+"]");
   }

   public void onHandshakeFailure(Exception cause)
   {
      System.out.println("handshake failure");

       cause.printStackTrace();
   }

   public void onHandshakeSuccess()
   {
      System.out.println("handshake success");

       SSLSession session = engine.getSession();

       try
       {
          System.out.println("- local principal: " + session.getLocalPrincipal());
          System.out.println("- remote principal: " + session.getPeerPrincipal());
          System.out.println("- using cipher: " + session.getCipherSuite());
       }
       catch (Exception exc)
       {
          exc.printStackTrace();
       }
   }

   public void onClosed()
   {
      
   }

   public void send(final ByteBuffer data)
   {
      //wrapSrc.clear();
      System.out.println("send");
      this.ioWorker.execute(new Runnable()
      {
         @Override
         public void run()
         {
            wrapSrc.put(data);

            ClientRequestHandlerSSL.this.run();
         }
      });
   }

   public void receive(final ByteBuffer data)
   {
     unwrapSrc.clear();
     //unwrapDst.clear();
      System.out.println("receive");
      this.ioWorker.execute(new Runnable()
      {
         @Override
         public void run()
         {
            unwrapSrc.put(data);

            ClientRequestHandlerSSL.this.run();
         }
      });
   }

   public void run()
   {
      // executes non-blocking tasks on the IO-Worker
System.out.println("RUN");
      while (this.step())
      {
         continue;
      }
      System.out.println("Thread end");
      // apparently we hit a blocking-task...
   }

   private boolean step()
   {
      switch (engine.getHandshakeStatus())
      {
         case NOT_HANDSHAKING:
            System.out.println("not handshaking");
            boolean anything = false;
            {
               if (wrapSrc.position() > 0)
                  anything |= this.wrap();
               if (unwrapSrc.position() > 0)
                  anything |= this.unwrap();
            }
            return anything;

         case NEED_WRAP:
            System.out.println("need wrap");
            if (!this.wrap())
               return false;
            break;

         case NEED_UNWRAP:
            System.out.println("need unwrap");
            if (!this.unwrap())
               return false;
            break;

         case NEED_TASK:
            System.out.println("need task");
            final Runnable sslTask = engine.getDelegatedTask();
            Runnable wrappedTask = new Runnable()
            {
               @Override
               public void run()
               {
                  System.out.println("async SSL task: " + sslTask);
                  long t0 = System.nanoTime();
                  sslTask.run();
                  long t1 = System.nanoTime();
                  System.out.println("async SSL task took: " + (t1 - t0) / 1000000 + "ms");

                  // continue handling I/O
                  ioWorker.execute(ClientRequestHandlerSSL.this);
               }
            };
            taskWorkers.execute(wrappedTask);
            return false;

         case FINISHED:
            System.out.println("finished");
            throw new IllegalStateException("FINISHED");
      }
      System.out.println("true");
      return true;
   }

   private boolean wrap()
   {
      SSLEngineResult wrapResult;

      try
      {
         wrapSrc.flip();
         wrapResult = engine.wrap(wrapSrc, wrapDst);
         wrapSrc.compact();
      }
      catch (SSLException exc)
      {
         this.onHandshakeFailure(exc);
         return false;
      }

      switch (wrapResult.getStatus())
      {
         case OK:
            System.out.println("Wrap: OK");
            if (wrapDst.position() > 0)
            {
               wrapDst.flip();
               System.out.println("calling handleReceiveData");
               this.handleReceivedData(wrapDst);
               wrapDst.compact();
            }
            break;

         case BUFFER_UNDERFLOW:
            System.out.println("Wrap: Buffer underflow");
            // try again later
            break;

         case BUFFER_OVERFLOW:
            System.out.println("Wrap: Buffer overflow");
            throw new IllegalStateException("failed to wrap");

         case CLOSED:
            this.onClosed();
            return false;
      }

      return true;
   }

   private boolean unwrap()
   {
      SSLEngineResult unwrapResult;

      try
      {
         unwrapSrc.flip();
         unwrapResult = engine.unwrap(unwrapSrc, unwrapDst);
         unwrapSrc.compact();
      }
      catch (SSLException exc)
      {
         this.onHandshakeFailure(exc);
         return false;
      }

      switch (unwrapResult.getStatus())
      {
         case OK:
            System.out.println("Unwrap: OK");
            if (unwrapDst.position() > 0)
            {
               unwrapDst.flip();
               System.out.println("calling handleSendData");
               this.handleSendData(unwrapDst);
               unwrapDst.compact();
            }
            break;

         case CLOSED:
            this.onClosed();
            return false;

         case BUFFER_OVERFLOW:
            throw new IllegalStateException("failed to unwrap");

         case BUFFER_UNDERFLOW:
            System.out.println("Unwrap: Buffer underflow");
            return false;
      }

      switch (unwrapResult.getHandshakeStatus())
      {
         case FINISHED:
            this.onHandshakeSuccess();
            return false;
      }

      return true;
   }
}

My SSLContext implementation

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17

KeyStore ks = KeyStore.getInstance("JKS");
            KeyStore ts = KeyStore.getInstance("JKS");
            FileInputStream fin = new FileInputStream(keyStoreFilePath);
            ks.load(fin, keyStoreFilePassword.toCharArray());
      
            // Set up key manager factory to use our key store
            // Assume key password is the same as the key store file
            // password
            KeyManagerFactory kmf = KeyManagerFactory.getInstance("SunX509");
            kmf.init(ks, keyStoreFilePassword.toCharArray());
            
            TrustManagerFactory tmf = TrustManagerFactory.getInstance("SunX509");
            tmf.init(ts);
            
            // Initialize the SSLContext to work with our key managers.
            sslContext = SSLContext.getInstance("TLS");
            sslContext.init(kmf.getKeyManagers(), tmf.getTrustManagers(), null);

This is the result printed by ClientRequestHandlerSSL class to eclipse console when I open the secure websocket in Chrome:
construct read
Allocate RCV Buffer size: [65536]
receive
RUN
need unwrap
Unwrap: Buffer underflow
Thread end
RUN
need unwrap
Unwrap: OK
true
need task
Thread end
async SSL task: sun.security.ssl.Handshaker$DelegatedTask@1d0fe80
async SSL task took: 44ms
RUN
need wrap
Wrap: OK
calling handleReceiveData
true
need unwrap
Unwrap: Buffer underflow
Thread end

The code seems to work as but the result data written to my server logfile by "handleReceivedData" seems to be messed up. I can partially see data of my SSL certificate along with unreadable data. Obviously I do something terribly wrong.
I hope someone can please point me in the right direction?