1 /*
2  * Copyright (c) 2000, 2005, 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 /*
27  *
28  *  (C) Copyright IBM Corp. 1999 All Rights Reserved.
29  *  Copyright 1997 The Open Group Research Institute.  All rights reserved.
30  */
31 
32 package sun.security.krb5.internal.util;
33 
34 import java.io.BufferedInputStream;
35 import java.io.InputStream;
36 import java.io.IOException;
37 
38 /**
39  * This class implements a buffered input stream. It provides methods to read a chunck
40  * of data from underlying data stream.
41  *
42  * @author Yanni Zhang
43  *
44  */
45 public class KrbDataInputStream extends BufferedInputStream{
46     private boolean bigEndian = true;
47 
setNativeByteOrder()48     public void setNativeByteOrder() {
49         if (java.nio.ByteOrder.nativeOrder().
50                 equals(java.nio.ByteOrder.BIG_ENDIAN)) {
51             bigEndian = true;
52         } else {
53             bigEndian = false;
54         }
55     }
KrbDataInputStream(InputStream is)56     public KrbDataInputStream(InputStream is){
57         super(is);
58     }
59 
60     /**
61      * Reads a length value which is represented in 4 bytes from
62      * this input stream. The value must be positive.
63      * @return the length value represented by this byte array.
64      * @throws IOException if there are not enough bytes or it represents
65      * a negative value
66      */
readLength4()67     final public int readLength4() throws IOException {
68         int len = read(4);
69         if (len < 0) {
70             throw new IOException("Invalid encoding");
71         }
72         return len;
73     }
74 
75     /**
76      * Reads up to the specific number of bytes from this input stream.
77      * @param num the number of bytes to be read.
78      * @return the int value of this byte array.
79      * @throws IOException if there are not enough bytes
80      */
read(int num)81     public int read(int num) throws IOException {
82         byte[] bytes = new byte[num];
83         if (read(bytes, 0, num) != num) {
84             throw new IOException("Premature end of stream reached");
85         }
86         int result = 0;
87         for (int i = 0; i < num; i++) {
88             if (bigEndian) {
89                 result |= (bytes[i] & 0xff) << (num - i - 1) * 8;
90             } else {
91                 result |= (bytes[i] & 0xff) << i * 8;
92             }
93         }
94         return result;
95     }
96 
readVersion()97     public int readVersion() throws IOException {
98         // always read in big-endian mode
99         int result = (read() & 0xff) << 8;
100         return result | (read() & 0xff);
101     }
102 }
103