1 /* 2 * Copyright (c) 1996, 2013, 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 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} 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} 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 original digest untouched. 56 * 57 * @see MessageDigest 58 * 59 * @see DigestOutputStream 60 * 61 * @author Benjamin Renaud 62 * @since 1.2 63 */ 64 65 public class DigestInputStream extends FilterInputStream { 66 67 /* NOTE: This should be made a generic UpdaterInputStream */ 68 69 /* Are we on or off? */ 70 private boolean on = true; 71 72 /** 73 * The message digest associated with this stream. 74 */ 75 protected MessageDigest digest; 76 77 /** 78 * Creates a digest input stream, using the specified input stream 79 * and message digest. 80 * 81 * @param stream the input stream. 82 * 83 * @param digest the message digest to associate with this stream. 84 */ DigestInputStream(InputStream stream, MessageDigest digest)85 public DigestInputStream(InputStream stream, MessageDigest digest) { 86 super(stream); 87 setMessageDigest(digest); 88 } 89 90 /** 91 * Returns the message digest associated with this stream. 92 * 93 * @return the message digest associated with this stream. 94 * @see #setMessageDigest(java.security.MessageDigest) 95 */ getMessageDigest()96 public MessageDigest getMessageDigest() { 97 return digest; 98 } 99 100 /** 101 * Associates the specified message digest with this stream. 102 * 103 * @param digest the message digest to be associated with this stream. 104 * @see #getMessageDigest() 105 */ setMessageDigest(MessageDigest digest)106 public void setMessageDigest(MessageDigest digest) { 107 this.digest = digest; 108 } 109 110 /** 111 * Reads a byte, and updates the message digest (if the digest 112 * function is on). That is, this method reads a byte from the 113 * input stream, blocking until the byte is actually read. If the 114 * digest function is on (see {@link #on(boolean) on}), this method 115 * will then call {@code update} on the message digest associated 116 * with this stream, passing it the byte read. 117 * 118 * @return the byte read. 119 * 120 * @exception IOException if an I/O error occurs. 121 * 122 * @see MessageDigest#update(byte) 123 */ read()124 public int read() throws IOException { 125 int ch = in.read(); 126 if (on && ch != -1) { 127 digest.update((byte)ch); 128 } 129 return ch; 130 } 131 132 /** 133 * Reads into a byte array, and updates the message digest (if the 134 * digest function is on). That is, this method reads up to 135 * {@code len} bytes from the input stream into the array 136 * {@code b}, starting at offset {@code off}. This method 137 * blocks until the data is actually 138 * read. If the digest function is on (see 139 * {@link #on(boolean) on}), this method will then call {@code update} 140 * on the message digest associated with this stream, passing it 141 * the data. 142 * 143 * @param b the array into which the data is read. 144 * 145 * @param off the starting offset into {@code b} of where the 146 * data should be placed. 147 * 148 * @param len the maximum number of bytes to be read from the input 149 * stream into b, starting at offset {@code off}. 150 * 151 * @return the actual number of bytes read. This is less than 152 * {@code len} if the end of the stream is reached prior to 153 * reading {@code len} bytes. -1 is returned if no bytes were 154 * read because the end of the stream had already been reached when 155 * the call was made. 156 * 157 * @exception IOException if an I/O error occurs. 158 * 159 * @see MessageDigest#update(byte[], int, int) 160 */ read(byte[] b, int off, int len)161 public int read(byte[] b, int off, int len) throws IOException { 162 int result = in.read(b, off, len); 163 if (on && result != -1) { 164 digest.update(b, off, result); 165 } 166 return result; 167 } 168 169 /** 170 * Turns the digest function on or off. The default is on. When 171 * it is on, a call to one of the {@code read} methods results in an 172 * update on the message digest. But when it is off, the message 173 * digest is not updated. 174 * 175 * @param on true to turn the digest function on, false to turn 176 * it off. 177 */ on(boolean on)178 public void on(boolean on) { 179 this.on = on; 180 } 181 182 /** 183 * Prints a string representation of this digest input stream and 184 * its associated message digest object. 185 */ toString()186 public String toString() { 187 return "[Digest Input Stream] " + digest.toString(); 188 } 189 } 190