1 /*
2 * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package javax.smartcardio;
27
28 import java.util.Arrays;
29
30 /**
31 * A response APDU as defined in ISO/IEC 7816-4. It consists of a conditional
32 * body and a two byte trailer.
33 * This class does not attempt to verify that the APDU encodes a semantically
34 * valid response.
35 *
36 * <p>Instances of this class are immutable. Where data is passed in or out
37 * via byte arrays, defensive cloning is performed.
38 *
39 * @see CommandAPDU
40 * @see CardChannel#transmit CardChannel.transmit
41 *
42 * @since 1.6
43 * @author Andreas Sterbenz
44 * @author JSR 268 Expert Group
45 */
46 public final class ResponseAPDU implements java.io.Serializable {
47
48 private static final long serialVersionUID = 6962744978375594225L;
49
50 /** @serial */
51 private byte[] apdu;
52
53 /**
54 * Constructs a ResponseAPDU from a byte array containing the complete
55 * APDU contents (conditional body and trailed).
56 *
57 * <p>Note that the byte array is cloned to protect against subsequent
58 * modification.
59 *
60 * @param apdu the complete response APDU
61 *
62 * @throws NullPointerException if apdu is null
63 * @throws IllegalArgumentException if apdu.length is less than 2
64 */
65 public ResponseAPDU(byte[] apdu) {
66 apdu = apdu.clone();
67 check(apdu);
68 this.apdu = apdu;
69 }
70
71 private static void check(byte[] apdu) {
72 if (apdu.length < 2) {
73 throw new IllegalArgumentException("apdu must be at least 2 bytes long");
74 }
75 }
76
77 /**
78 * Returns the number of data bytes in the response body (Nr) or 0 if this
79 * APDU has no body. This call is equivalent to
80 * <code>getData().length</code>.
81 *
82 * @return the number of data bytes in the response body or 0 if this APDU
83 * has no body.
84 */
85 public int getNr() {
86 return apdu.length - 2;
87 }
88
89 /**
90 * Returns a copy of the data bytes in the response body. If this APDU as
91 * no body, this method returns a byte array with a length of zero.
92 *
93 * @return a copy of the data bytes in the response body or the empty
94 * byte array if this APDU has no body.
95 */
96 public byte[] getData() {
97 byte[] data = new byte[apdu.length - 2];
98 System.arraycopy(apdu, 0, data, 0, data.length);
99 return data;
100 }
101
102 /**
103 * Returns the value of the status byte SW1 as a value between 0 and 255.
104 *
105 * @return the value of the status byte SW1 as a value between 0 and 255.
106 */
107 public int getSW1() {
108 return apdu[apdu.length - 2] & 0xff;
109 }
110
111 /**
112 * Returns the value of the status byte SW2 as a value between 0 and 255.
113 *
114 * @return the value of the status byte SW2 as a value between 0 and 255.
115 */
116 public int getSW2() {
117 return apdu[apdu.length - 1] & 0xff;
118 }
119
120 /**
121 * Returns the value of the status bytes SW1 and SW2 as a single
122 * status word SW.
123 * It is defined as
124 * <code>(getSW1() << 8) | getSW2()</code>.
125 *
126 * @return the value of the status word SW.
127 */
128 public int getSW() {
129 return (getSW1() << 8) | getSW2();
130 }
131
132 /**
133 * Returns a copy of the bytes in this APDU.
134 *
135 * @return a copy of the bytes in this APDU.
136 */
137 public byte[] getBytes() {
138 return apdu.clone();
139 }
140
141 /**
142 * Returns a string representation of this response APDU.
143 *
144 * @return a String representation of this response APDU.
145 */
146 public String toString() {
147 return "ResponseAPDU: " + apdu.length + " bytes, SW="
148 + Integer.toHexString(getSW());
149 }
150
151 /**
152 * Compares the specified object with this response APDU for equality.
153 * Returns true if the given object is also a ResponseAPDU and its bytes are
154 * identical to the bytes in this ResponseAPDU.
155 *
156 * @param obj the object to be compared for equality with this response APDU
157 * @return true if the specified object is equal to this response APDU
158 */
159 public boolean equals(Object obj) {
160 if (this == obj) {
161 return true;
162 }
163 if (obj instanceof ResponseAPDU == false) {
164 return false;
165 }
166 ResponseAPDU other = (ResponseAPDU)obj;
167 return Arrays.equals(this.apdu, other.apdu);
168 }
169
170 /**
171 * Returns the hash code value for this response APDU.
172 *
173 * @return the hash code value for this response APDU.
174 */
175 public int hashCode() {
176 return Arrays.hashCode(apdu);
177 }
178
179 private void readObject(java.io.ObjectInputStream in)
180 throws java.io.IOException, ClassNotFoundException {
181 apdu = (byte[])in.readUnshared();
182 check(apdu);
183 }
184
185 }