1/*
2 * Copyright (c) 2000, 2012, 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
32package sun.security.krb5.internal.ktab;
33
34import sun.security.krb5.internal.*;
35import sun.security.krb5.PrincipalName;
36import sun.security.krb5.Realm;
37import sun.security.krb5.RealmException;
38import sun.security.krb5.internal.util.KrbDataInputStream;
39import java.io.IOException;
40import java.io.InputStream;
41
42/**
43 * This class implements a buffered input stream. It is used for parsing key table
44 * data to memory.
45 *
46 * @author Yanni Zhang
47 *
48 */
49public class KeyTabInputStream extends KrbDataInputStream implements KeyTabConstants {
50
51    boolean DEBUG = Krb5.DEBUG;
52    int index;
53
54    public KeyTabInputStream(InputStream is) {
55        super(is);
56    }
57    /**
58     * Reads the number of bytes this entry data occupy.
59     */
60    int readEntryLength() throws IOException {
61        return read(4);
62    }
63
64
65    KeyTabEntry readEntry(int entryLen, int ktVersion) throws IOException, RealmException {
66        index = entryLen;
67        if (index == 0) {    //in native implementation, when the last entry is deleted, a byte 0 is left.
68            return null;
69        }
70        if (index < 0) {    //in native implementation, when one of the entries is deleted, the entry length turns to be negative, and
71            skip(Math.abs(index));                //the fields are left with 0 bytes
72            return null;
73        }
74        int principalNum = read(2);     //the number of service names.
75        index -= 2;
76        if (ktVersion == KRB5_KT_VNO_1) {   //V1 includes realm in the count.
77            principalNum -= 1;
78        }
79        Realm realm = new Realm(readName());
80        String[] nameParts = new String[principalNum];
81        for (int i = 0; i < principalNum; i++) {
82            nameParts[i] = readName();
83        }
84        int nameType = read(4);
85        index -= 4;
86        PrincipalName service = new PrincipalName(nameType, nameParts, realm);
87        KerberosTime timeStamp = readTimeStamp();
88
89        int keyVersion = read() & 0xff;
90        index -= 1;
91        int keyType = read(2);
92        index -= 2;
93        int keyLength = read(2);
94        index -= 2;
95        byte[] keyblock = readKey(keyLength);
96        index -= keyLength;
97        // There might be a 32 bit kvno here.
98        // If index is zero, assume that the 8 bit key version number was
99        // right, otherwise trust the new nonzero value.
100        if (index >= 4) {
101            int extKvno = read(4);
102            if (extKvno != 0) {
103                keyVersion = extKvno;
104            }
105            index -= 4;
106        }
107
108        // if index is negative, the keytab format must be wrong.
109        if (index < 0) {
110            throw new RealmException("Keytab is corrupted");
111        }
112
113        // ignore the left bytes.
114        skip(index);
115
116        return new KeyTabEntry(service, realm, timeStamp, keyVersion, keyType, keyblock);
117    }
118
119    byte[] readKey(int length) throws IOException {
120        byte[] bytes = new byte[length];
121        read(bytes, 0, length);
122        return bytes;
123    }
124
125    KerberosTime readTimeStamp() throws IOException {
126        index -= 4;
127        return new KerberosTime((long)read(4) * 1000);
128    }
129
130    String readName() throws IOException {
131        String name;
132        int length = read(2);   //length of the realm name or service name
133        index -= 2;
134        byte[] bytes = new byte[length];
135        read(bytes, 0, length);
136        index -= length;
137        name = new String(bytes);
138        if (DEBUG) {
139            System.out.println(">>> KeyTabInputStream, readName(): " + name);
140        }
141        return name;
142    }
143}
144