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 * https://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
21 package org.apache.directory.api.asn1.util;
22
23 import java.nio.ByteBuffer;
24
25 /**
26 * A buffer used to store an encoding PDU. It's auto-extended, and
27 * filled by the end.
28 *
29 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
30 */
31 public class Asn1Buffer
32 {
33 /** The buffer default size */
34 private static final int DEFAULT_SIZE = 1024;
35
36 /** The current position in the buffer */
37 private int pos = 0;
38
39 /** A buffer to store the encoded PDU */
40 private byte[] buffer;
41
42
43 /**
44 * Creates a new Asn1Buffer instance
45 */
46 public Asn1Buffer()
47 {
48 buffer = new byte[DEFAULT_SIZE];
49 }
50
51
52 /**
53 * @return The current position in the buffer
54 */
55 public int getPos()
56 {
57 return pos;
58 }
59
60
61 /**
62 * Set the current position in the buffer
63 *
64 * @param pos The position to move the buffer to
65 */
66 public void setPos( int pos )
67 {
68 this.pos = pos;
69 }
70
71
72 /**
73 * Store a byte at the current position in the buffer
74 *
75 * @param b The byte to store
76 */
77 public void put( byte b )
78 {
79 if ( pos == buffer.length )
80 {
81 // The buffer needs to be reallocated, its too small
82 extend( 1 );
83 }
84
85 pos++;
86 buffer[buffer.length - pos] = b;
87 }
88
89
90 /**
91 * Store some bytes at the current position in the buffer
92 *
93 * @param bytes The bytes to store
94 */
95 public void put( byte[] bytes )
96 {
97 if ( pos + bytes.length > buffer.length )
98 {
99 // The buffer needs to be reallocated, its too small
100 extend( bytes.length );
101 }
102
103
104 pos += bytes.length;
105 System.arraycopy( bytes, 0, buffer, buffer.length - pos, bytes.length );
106 }
107
108
109 /**
110 * Extend the buffer
111 *
112 * @param size The new buffer size
113 */
114 private void extend( int size )
115 {
116 // The buffer needs to be reallocated, it's too small
117 int newSize = ( ( size + buffer.length ) / DEFAULT_SIZE ) * DEFAULT_SIZE;
118
119 if ( size % DEFAULT_SIZE != 0 )
120 {
121 newSize += DEFAULT_SIZE;
122 }
123
124 byte[] newBuffer = new byte[newSize];
125 System.arraycopy( buffer, 0, newBuffer, newSize - buffer.length, buffer.length );
126
127 buffer = newBuffer;
128 }
129
130
131 /**
132 * @return The stored encoded PDU.
133 */
134 public ByteBuffer getBytes()
135 {
136 ByteBuffer result = ByteBuffer.allocate( pos );
137
138 result.put( buffer, buffer.length - pos, pos );
139 result.flip();
140
141 return result;
142 }
143
144
145 /**
146 * @return The buffer size (ie the maximum number of bytes that can be
147 * added to this bffder before it gets extended).
148 */
149 public int getSize()
150 {
151 return buffer.length;
152 }
153
154
155 /**
156 * Clear the position, emptying the buffer. If it has grown, reallocate it
157 * to its initial size.
158 */
159 public void clear()
160 {
161 if ( buffer.length > DEFAULT_SIZE )
162 {
163 buffer = new byte[DEFAULT_SIZE];
164 }
165
166 pos = 0;
167 }
168
169
170 /**
171 * {@inheritDoc}
172 */
173 @Override
174 public String toString()
175 {
176 return "[" + buffer.length + ", " + pos + "] '"
177 + Asn1StringUtils.dumpBytes( buffer, buffer.length - pos, pos ) + '\'';
178 }
179 }