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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *  
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *  
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License. 
18   *  
19   */
20  package org.apache.mina.filter.support;
21  
22  import java.nio.ByteBuffer;
23  
24  import javax.net.ssl.SSLEngine;
25  
26  import org.apache.mina.util.Stack;
27  
28  /**
29   * Simple ByteBuffer pool used by SSLHandler.
30   * ByteBuffers are by default allocated as direct byte buffers. To use non-direct
31   * ByteBuffers, set system property mina.sslfilter.directbuffer to false.
32   *
33   * @author The Apache Directory Project (mina-dev@directory.apache.org)
34   * @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 (Fri, 13 Jul 2007) $
35   */
36  class SSLByteBufferPool {
37      private static final int PACKET_BUFFER_INDEX = 0;
38  
39      private static final int APPLICATION_BUFFER_INDEX = 1;
40  
41      private static boolean initiated = false;
42  
43      private static final String DIRECT_MEMORY_PROP = "mina.sslfilter.directbuffer";
44  
45      private static boolean useDirectAllocatedBuffers = true;
46  
47      private static int packetBufferSize;
48  
49      private static int appBufferSize;
50  
51      private static int[] bufferStackSizes;
52  
53      private static final Stack[] bufferStacks = new Stack[] { new Stack(),
54              new Stack(), };
55  
56      /**
57       * Initiate buffer pool and buffer sizes from SSLEngine session.
58       *
59       * @param sslEngine SSLEngine
60       */
61      static synchronized void initiate(SSLEngine sslEngine) {
62          if (!initiated) {
63              // Use direct allocated memory or not?
64              String prop = System.getProperty(DIRECT_MEMORY_PROP);
65              if (prop != null) {
66                  useDirectAllocatedBuffers = Boolean
67                          .getBoolean(DIRECT_MEMORY_PROP);
68              }
69  
70              // init buffer sizes from SSLEngine
71              packetBufferSize = sslEngine.getSession().getPacketBufferSize();
72  
73              // application buffer size has been doubled because SSLEngine
74              // returns BUFFER_OVERFLOW even if there is enough room for the buffer.
75              // So for now we use a size double the packet size as a workaround.
76              appBufferSize = packetBufferSize * 2;
77              initiateBufferStacks();
78              initiated = true;
79          }
80      }
81  
82      /**
83       * Get bytebuffer with size the size of the largest SSL/TLS packet that may occur
84       * (as defined by SSLSession).
85       */
86      static ByteBuffer getPacketBuffer() {
87          if (!initiated) {
88              throw new IllegalStateException("Not initialized");
89          }
90          return allocate(PACKET_BUFFER_INDEX);
91      }
92  
93      /**
94       * Get ByteBuffer with the size of the largest application buffer that may occur
95       * (as defined by SSLSession).
96       */
97      static ByteBuffer getApplicationBuffer() {
98          if (!initiated) {
99              throw new IllegalStateException("Not initialized");
100         }
101         return allocate(APPLICATION_BUFFER_INDEX);
102     }
103 
104     /**
105      * Allocate or get the buffer which is capable of the specified size.
106      */
107     private static ByteBuffer allocate(int idx) {
108         Stack stack = bufferStacks[idx];
109 
110         ByteBuffer buf;
111         synchronized (stack) {
112             buf = (ByteBuffer) stack.pop();
113             if (buf == null) {
114                 buf = createBuffer(bufferStackSizes[idx]);
115             }
116         }
117 
118         buf.clear();
119         return buf;
120     }
121 
122     /**
123      * Releases the specified buffer to buffer pool.
124      */
125     public static void release(ByteBuffer buf) {
126         // Sweep buffer for security.
127         org.apache.mina.common.ByteBuffer.wrap(buf).sweep().release();
128 
129         int stackIndex = getBufferStackIndex(buf.capacity());
130         if (stackIndex >= PACKET_BUFFER_INDEX) {
131             Stack stack = bufferStacks[getBufferStackIndex(buf.capacity())];
132             synchronized (stack) {
133                 stack.push(buf);
134             }
135         }
136     }
137 
138     /**
139      * Expand size of provided buffer
140      * @param buf buffer to be expande
141      * @param newCapacity new capacity
142      */
143     public static ByteBuffer expandBuffer(ByteBuffer buf, int newCapacity) {
144         ByteBuffer newBuf = createBuffer(newCapacity);
145         buf.flip();
146         newBuf.put(buf);
147         release(buf);
148         return newBuf;
149     }
150 
151     private static void initiateBufferStacks() {
152         bufferStackSizes = new int[2];
153         bufferStackSizes[PACKET_BUFFER_INDEX] = packetBufferSize;
154         bufferStackSizes[APPLICATION_BUFFER_INDEX] = appBufferSize;
155     }
156 
157     private static int getBufferStackIndex(int size) {
158         if (size == packetBufferSize)
159             return PACKET_BUFFER_INDEX;
160         if (size == appBufferSize)
161             return APPLICATION_BUFFER_INDEX;
162         return -1; // not reused
163     }
164 
165     private static ByteBuffer createBuffer(int capacity) {
166         if (useDirectAllocatedBuffers) {
167             try {
168                 return ByteBuffer.allocateDirect(capacity);
169             } catch (OutOfMemoryError e) {
170                 useDirectAllocatedBuffers = false;
171                 System.err
172                         .println("OutOfMemoryError: No more direct buffers available; trying heap buffer instead");
173             }
174         }
175         return ByteBuffer.allocate(capacity);
176     }
177 
178 }