J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1996-1999 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package java.security; |
| 27 | |
| 28 | import java.io.IOException; |
| 29 | import java.io.EOFException; |
| 30 | import java.io.InputStream; |
| 31 | import java.io.FilterInputStream; |
| 32 | import java.io.PrintStream; |
| 33 | import java.io.ByteArrayInputStream; |
| 34 | |
| 35 | /** |
| 36 | * A transparent stream that updates the associated message digest using |
| 37 | * the bits going through the stream. |
| 38 | * |
| 39 | * <p>To complete the message digest computation, call one of the |
| 40 | * <code>digest</code> methods on the associated message |
| 41 | * digest after your calls to one of this digest input stream's |
| 42 | * {@link #read() read} methods. |
| 43 | * |
| 44 | * <p>It is possible to turn this stream on or off (see |
| 45 | * {@link #on(boolean) on}). When it is on, a call to one of the |
| 46 | * <code>read</code> methods |
| 47 | * results in an update on the message digest. But when it is off, |
| 48 | * the message digest is not updated. The default is for the stream |
| 49 | * to be on. |
| 50 | * |
| 51 | * <p>Note that digest objects can compute only one digest (see |
| 52 | * {@link MessageDigest}), |
| 53 | * so that in order to compute intermediate digests, a caller should |
| 54 | * retain a handle onto the digest object, and clone it for each |
| 55 | * digest to be computed, leaving the orginal digest untouched. |
| 56 | * |
| 57 | * @see MessageDigest |
| 58 | * |
| 59 | * @see DigestOutputStream |
| 60 | * |
| 61 | * @author Benjamin Renaud |
| 62 | */ |
| 63 | |
| 64 | public class DigestInputStream extends FilterInputStream { |
| 65 | |
| 66 | /* NOTE: This should be made a generic UpdaterInputStream */ |
| 67 | |
| 68 | /* Are we on or off? */ |
| 69 | private boolean on = true; |
| 70 | |
| 71 | /** |
| 72 | * The message digest associated with this stream. |
| 73 | */ |
| 74 | protected MessageDigest digest; |
| 75 | |
| 76 | /** |
| 77 | * Creates a digest input stream, using the specified input stream |
| 78 | * and message digest. |
| 79 | * |
| 80 | * @param stream the input stream. |
| 81 | * |
| 82 | * @param digest the message digest to associate with this stream. |
| 83 | */ |
| 84 | public DigestInputStream(InputStream stream, MessageDigest digest) { |
| 85 | super(stream); |
| 86 | setMessageDigest(digest); |
| 87 | } |
| 88 | |
| 89 | /** |
| 90 | * Returns the message digest associated with this stream. |
| 91 | * |
| 92 | * @return the message digest associated with this stream. |
| 93 | * @see #setMessageDigest(java.security.MessageDigest) |
| 94 | */ |
| 95 | public MessageDigest getMessageDigest() { |
| 96 | return digest; |
| 97 | } |
| 98 | |
| 99 | /** |
| 100 | * Associates the specified message digest with this stream. |
| 101 | * |
| 102 | * @param digest the message digest to be associated with this stream. |
| 103 | * @see #getMessageDigest() |
| 104 | */ |
| 105 | public void setMessageDigest(MessageDigest digest) { |
| 106 | this.digest = digest; |
| 107 | } |
| 108 | |
| 109 | /** |
| 110 | * Reads a byte, and updates the message digest (if the digest |
| 111 | * function is on). That is, this method reads a byte from the |
| 112 | * input stream, blocking until the byte is actually read. If the |
| 113 | * digest function is on (see {@link #on(boolean) on}), this method |
| 114 | * will then call <code>update</code> on the message digest associated |
| 115 | * with this stream, passing it the byte read. |
| 116 | * |
| 117 | * @return the byte read. |
| 118 | * |
| 119 | * @exception IOException if an I/O error occurs. |
| 120 | * |
| 121 | * @see MessageDigest#update(byte) |
| 122 | */ |
| 123 | public int read() throws IOException { |
| 124 | int ch = in.read(); |
| 125 | if (on && ch != -1) { |
| 126 | digest.update((byte)ch); |
| 127 | } |
| 128 | return ch; |
| 129 | } |
| 130 | |
| 131 | /** |
| 132 | * Reads into a byte array, and updates the message digest (if the |
| 133 | * digest function is on). That is, this method reads up to |
| 134 | * <code>len</code> bytes from the input stream into the array |
| 135 | * <code>b</code>, starting at offset <code>off</code>. This method |
| 136 | * blocks until the data is actually |
| 137 | * read. If the digest function is on (see |
| 138 | * {@link #on(boolean) on}), this method will then call <code>update</code> |
| 139 | * on the message digest associated with this stream, passing it |
| 140 | * the data. |
| 141 | * |
| 142 | * @param b the array into which the data is read. |
| 143 | * |
| 144 | * @param off the starting offset into <code>b</code> of where the |
| 145 | * data should be placed. |
| 146 | * |
| 147 | * @param len the maximum number of bytes to be read from the input |
| 148 | * stream into b, starting at offset <code>off</code>. |
| 149 | * |
| 150 | * @return the actual number of bytes read. This is less than |
| 151 | * <code>len</code> if the end of the stream is reached prior to |
| 152 | * reading <code>len</code> bytes. -1 is returned if no bytes were |
| 153 | * read because the end of the stream had already been reached when |
| 154 | * the call was made. |
| 155 | * |
| 156 | * @exception IOException if an I/O error occurs. |
| 157 | * |
| 158 | * @see MessageDigest#update(byte[], int, int) |
| 159 | */ |
| 160 | public int read(byte[] b, int off, int len) throws IOException { |
| 161 | int result = in.read(b, off, len); |
| 162 | if (on && result != -1) { |
| 163 | digest.update(b, off, result); |
| 164 | } |
| 165 | return result; |
| 166 | } |
| 167 | |
| 168 | /** |
| 169 | * Turns the digest function on or off. The default is on. When |
| 170 | * it is on, a call to one of the <code>read</code> methods results in an |
| 171 | * update on the message digest. But when it is off, the message |
| 172 | * digest is not updated. |
| 173 | * |
| 174 | * @param on true to turn the digest function on, false to turn |
| 175 | * it off. |
| 176 | */ |
| 177 | public void on(boolean on) { |
| 178 | this.on = on; |
| 179 | } |
| 180 | |
| 181 | /** |
| 182 | * Prints a string representation of this digest input stream and |
| 183 | * its associated message digest object. |
| 184 | */ |
| 185 | public String toString() { |
| 186 | return "[Digest Input Stream] " + digest.toString(); |
| 187 | } |
| 188 | } |