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1: /* InputBuffer.java -- 2: Copyright (C) 2003, 2006 Free Software Foundation, Inc. 3: 4: This file is a part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2 of the License, or (at 9: your option) any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; if not, write to the Free Software 18: Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 19: USA 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: 39: package gnu.javax.crypto.sasl; 40: 41: import gnu.java.security.Registry; 42: 43: import java.io.ByteArrayInputStream; 44: import java.io.IOException; 45: import java.math.BigInteger; 46: 47: /** 48: * The implementation of an incoming SASL buffer. 49: * <p> 50: * The data elements this class caters for are described in [1]. 51: * <p> 52: * References: 53: * <ol> 54: * <li><a 55: * href="http://www.ietf.org/internet-drafts/draft-burdis-cat-srp-sasl-09.txt"> 56: * Secure Remote Password Authentication Mechanism</a>;<br/> 57: * draft-burdis-cat-srp-sasl-09,<br/> <a 58: * href="mailto:keith@rucus.ru.ac.za">Keith Burdis</a> and <a 59: * href="mailto:raif@forge.com.au">Raïf S. Naffah</a>.</li> 60: * </ol> 61: */ 62: public class InputBuffer 63: { 64: /** The internal buffer stream containing the buffer's contents. */ 65: protected ByteArrayInputStream in; 66: /** The length of the buffer, according to its header. */ 67: protected int length; 68: 69: /** 70: * Constructs a SASL buffer given the buffer's encoded form, including its 71: * header bytes. 72: * 73: * @param frame the encoded form, including the header bytes, of a SASL 74: * buffer. 75: * @throws SaslEncodingException if the buffer is malformed. 76: */ 77: public InputBuffer(byte[] frame) throws SaslEncodingException 78: { 79: this(); 80: 81: if (frame.length < 4) 82: throw new SaslEncodingException("SASL buffer header too short"); 83: length = (frame[0] & 0xFF) << 24 84: | (frame[1] & 0xFF) << 16 85: | (frame[2] & 0xFF) << 8 86: | (frame[3] & 0xFF); 87: if (length > Registry.SASL_BUFFER_MAX_LIMIT || length < 0) 88: throw new SaslEncodingException("SASL buffer size limit exceeded"); 89: in = new ByteArrayInputStream(frame, 4, length); 90: } 91: 92: /** Trivial private constructor for use by the class method. */ 93: private InputBuffer() 94: { 95: super(); 96: } 97: 98: /** 99: * Returns an instance of a SASL buffer given the buffer's encoded contents, 100: * excluding the buffer's header bytes. 101: * <p> 102: * Calls the method with the same name and three arguments as: 103: * <code>getInstance(raw, 0, raw.length)</code>. 104: * 105: * @param raw the encoded form, excluding the header bytes, of a SASL buffer. 106: * @return a new instance of {@link InputBuffer}. 107: */ 108: public static InputBuffer getInstance(byte[] raw) 109: { 110: return getInstance(raw, 0, raw.length); 111: } 112: 113: /** 114: * Returns an instance of a SASL buffer given the buffer's encoded contents, 115: * excluding the buffer's header bytes. 116: * 117: * @param raw the encoded form, excluding the header bytes, of a SASL buffer. 118: * @param offset offset where to start using raw bytes from. 119: * @param len number of bytes to use. 120: * @return a new instance of {@link InputBuffer}. 121: */ 122: public static InputBuffer getInstance(byte[] raw, int offset, int len) 123: { 124: InputBuffer result = new InputBuffer(); 125: result.in = new ByteArrayInputStream(raw, offset, len); 126: return result; 127: } 128: 129: /** 130: * Converts two octets into the number that they represent. 131: * 132: * @param b the two octets. 133: * @return the length. 134: */ 135: public static int twoBytesToLength(byte[] b) throws SaslEncodingException 136: { 137: final int result = (b[0] & 0xFF) << 8 | (b[1] & 0xFF); 138: if (result > Registry.SASL_TWO_BYTE_MAX_LIMIT) 139: throw new SaslEncodingException("SASL MPI/Text size limit exceeded"); 140: return result; 141: } 142: 143: public boolean hasMoreElements() 144: { 145: return (in.available() > 0); 146: } 147: 148: /** 149: * Decodes a SASL scalar quantity, <code>count</code>-octet long, from the 150: * current buffer. 151: * 152: * @param count the number of octets of this scalar quantity. 153: * @return a native representation of a SASL scalar (unsigned integer) 154: * quantity. 155: * @throws SaslEncodingException if an encoding exception occurs during the 156: * operation. 157: * @throws IOException if any other I/O exception occurs during the operation. 158: */ 159: public long getScalar(int count) throws IOException 160: { 161: if (count < 0 || count > 4) 162: throw new SaslEncodingException("Invalid SASL scalar octet count: " 163: + String.valueOf(count)); 164: if (! hasMoreElements()) 165: throw new SaslEncodingException("Not enough bytes for a scalar in buffer"); 166: if (in.available() < count) 167: throw new SaslEncodingException("Illegal SASL scalar encoding"); 168: byte[] element = new byte[count]; 169: in.read(element); 170: long result = 0L; 171: for (int i = 0; i < count; i++) 172: { 173: result <<= 8; 174: result |= element[i] & 0xFFL; 175: } 176: return result; 177: } 178: 179: /** 180: * Decodes a SASL OS from the current buffer. 181: * 182: * @return a native representation of a SASL OS. 183: * @throws SaslEncodingException if an encoding exception occurs during the 184: * operation. 185: * @throws IOException if any other I/O exception occurs during the operation. 186: */ 187: public byte[] getOS() throws IOException 188: { 189: if (! hasMoreElements()) 190: throw new SaslEncodingException( 191: "Not enough bytes for an octet-sequence in buffer"); 192: final int elementLength = in.read(); 193: if (elementLength > Registry.SASL_ONE_BYTE_MAX_LIMIT) 194: throw new SaslEncodingException("SASL octet-sequence size limit exceeded"); 195: if (in.available() < elementLength) 196: throw new SaslEncodingException("Illegal SASL octet-sequence encoding"); 197: byte[] result = new byte[elementLength]; 198: in.read(result); 199: return result; 200: } 201: 202: /** 203: * Decodes a SASL EOS from the current buffer. 204: * 205: * @return a native representation of a SASL EOS. 206: * @throws SaslEncodingException if an encoding exception occurs during the 207: * operation. 208: * @throws IOException if any other I/O exception occurs during the operation. 209: */ 210: public byte[] getEOS() throws IOException 211: { 212: if (in.available() < 2) 213: throw new SaslEncodingException( 214: "Not enough bytes for an extended octet-sequence in buffer"); 215: byte[] elementLengthBytes = new byte[2]; 216: in.read(elementLengthBytes); 217: final int elementLength = twoBytesToLength(elementLengthBytes); 218: if (in.available() < elementLength) 219: throw new SaslEncodingException( 220: "Illegal SASL extended octet-sequence encoding"); 221: byte[] result = new byte[elementLength]; 222: in.read(result); 223: return result; 224: } 225: 226: /** 227: * Decodes a SASL MPI from the current buffer. 228: * 229: * @return a native representation of a SASL MPI. 230: * @throws SaslEncodingException if an encoding exception occurs during the 231: * operation. 232: * @throws IOException if any other I/O exception occurs during the operation. 233: */ 234: public BigInteger getMPI() throws IOException 235: { 236: if (in.available() < 2) 237: throw new SaslEncodingException("Not enough bytes for an MPI in buffer"); 238: byte[] elementLengthBytes = new byte[2]; 239: in.read(elementLengthBytes); 240: final int elementLength = twoBytesToLength(elementLengthBytes); 241: if (in.available() < elementLength) 242: throw new SaslEncodingException( 243: "Illegal SASL multi-precision integer encoding"); 244: byte[] element = new byte[elementLength]; 245: in.read(element); 246: return new BigInteger(1, element); 247: } 248: 249: /** 250: * Decodes a SASL Text from the current buffer. 251: * 252: * @return a native representation of a SASL Text. 253: * @throws SaslEncodingException if an encoding exception occurs during the 254: * operation. 255: * @throws SaslEncodingException if the UTF-8 character encoding is not 256: * supported on this platform. 257: * @throws IOException if any other I/O exception occurs during the operation. 258: */ 259: public String getText() throws IOException 260: { 261: if (in.available() < 2) 262: throw new SaslEncodingException("Not enough bytes for a text in buffer"); 263: byte[] elementLengthBytes = new byte[2]; 264: in.read(elementLengthBytes); 265: final int elementLength = twoBytesToLength(elementLengthBytes); 266: if (in.available() < elementLength) 267: throw new SaslEncodingException("Illegal SASL text encoding"); 268: byte[] element = new byte[elementLength]; 269: in.read(element); 270: return new String(element, "UTF8"); 271: } 272: }