package gnu.crypto.sasl;
// ----------------------------------------------------------------------------
// $Id: InputBuffer.java,v 1.5 2005/10/06 04:24:18 rsdio Exp $
//
// Copyright (C) 2003 Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// GNU Crypto is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; see the file COPYING. If not, write to the
//
// Free Software Foundation Inc.,
// 51 Franklin Street, Fifth Floor,
// Boston, MA 02110-1301
// USA
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library. Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give
// you permission to link this library with independent modules to
// produce an executable, regardless of the license terms of these
// independent modules, and to copy and distribute the resulting
// executable under terms of your choice, provided that you also meet,
// for each linked independent module, the terms and conditions of the
// license of that module. An independent module is a module which is
// not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the
// library, but you are not obligated to do so. If you do not wish to
// do so, delete this exception statement from your version.
// ----------------------------------------------------------------------------
import gnu.crypto.Registry;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.math.BigInteger;
/**
* <p>The implementation of an incoming SASL buffer.</p>
*
* <p>The data elements this class caters for are described in [1].</p>
*
* <p>References:</p>
* <ol>
* <li><a href="http://www.ietf.org/internet-drafts/draft-burdis-cat-srp-sasl-09.txt">
* Secure Remote Password Authentication Mechanism</a>;<br/>
* draft-burdis-cat-srp-sasl-09,<br/>
* <a href="mailto:keith@rucus.ru.ac.za">Keith Burdis</a> and
* <a href="mailto:raif@forge.com.au">Raïf S. Naffah</a>.</li>
* </ol>
*
* @version $Revision: 1.5 $
*/
public class InputBuffer {
// Constants and variables
// -------------------------------------------------------------------------
/** The internal buffer stream containing the buffer's contents. */
protected ByteArrayInputStream in;
/** The length of the buffer, according to its header. */
protected int length;
// Constructor(s)
// -------------------------------------------------------------------------
/**
* <p>Constructs a SASL buffer given the buffer's encoded form, including its
* header bytes.</p>
*
* @param frame the encoded form, including the header bytes, of a SASL buffer.
* @throws SaslEncodingException if the buffer is malformed.
*/
public InputBuffer(byte[] frame) throws SaslEncodingException {
this();
if (frame.length < 4) {
throw new SaslEncodingException("SASL buffer header too short");
}
length = (frame[0] & 0xFF) << 24 |
(frame[1] & 0xFF) << 16 |
(frame[2] & 0xFF) << 8 |
(frame[3] & 0xFF);
if (length > Registry.SASL_BUFFER_MAX_LIMIT || length < 0) {
throw new SaslEncodingException("SASL buffer size limit exceeded");
}
in = new ByteArrayInputStream(frame, 4, length);
}
/** Trivial private constructor for use by the class method. */
private InputBuffer() {
super();
}
// Class methods
// -------------------------------------------------------------------------
/**
* <p>Returns an instance of a SASL buffer given the buffer's encoded contents,
* excluding the buffer's header bytes.</p>
*
* <p>Calls the method with the same name and three arguments as:
* <code>getInstance(raw, 0, raw.length)</code>.
*
* @param raw the encoded form, excluding the header bytes, of a SASL buffer.
* @return a new instance of {@link InputBuffer}.
*/
public static InputBuffer getInstance(byte[] raw) {
return getInstance(raw, 0, raw.length);
}
/**
* <p>Returns an instance of a SASL buffer given the buffer's encoded
* contents, excluding the buffer's header bytes.</p>
*
* @param raw the encoded form, excluding the header bytes, of a SASL buffer.
* @param offset offset where to start using raw bytes from.
* @param len number of bytes to use.
* @return a new instance of {@link InputBuffer}.
*/
public static InputBuffer getInstance(byte[] raw, int offset, int len) {
InputBuffer result = new InputBuffer();
result.in = new ByteArrayInputStream(raw, offset, len);
return result;
}
/**
* <p>Converts four octets into the number that they represent.</p>
*
* @param b the four octets.
* @return the length.
*/
// public static int fourBytesToLength(byte[] b) throws SaslEncodingException {
// int result = b[0] << 24 | (b[1] & 0xFF) << 16 | (b[2] & 0xFF) << 8 | (b[3] & 0xFF);
// if (result > Registry.SASL_FOUR_BYTE_MAX_LIMIT || result < 0) {
// throw new SaslEncodingException("SASL EOS size limit exceeded");
// }
// return result;
// }
/**
* <p>Converts two octets into the number that they represent.</p>
*
* @param b the two octets.
* @return the length.
*/
public static int twoBytesToLength(byte[] b) throws SaslEncodingException {
final int result = (b[0] & 0xFF) << 8 | (b[1] & 0xFF);
if (result > Registry.SASL_TWO_BYTE_MAX_LIMIT) {
throw new SaslEncodingException("SASL MPI/Text size limit exceeded");
}
return result;
}
// Instance methods
// -------------------------------------------------------------------------
public boolean hasMoreElements() {
return (in.available() > 0);
}
/**
* <p>Decodes a SASL scalar quantity, <code>count</code>-octet long, from the
* current buffer.</p>
*
* @param count the number of octets of this scalar quantity.
* @return a native representation of a SASL scalar (unsigned integer) quantity.
* @throws SaslEncodingException if an encoding exception occurs during the
* operation.
* @throws IOException if any other I/O exception occurs during the operation.
*/
public long getScalar(int count) throws IOException {
if (count < 0 || count > 4) {
throw new SaslEncodingException("Invalid SASL scalar octet count: "
+String.valueOf(count));
}
if (!hasMoreElements()) {
throw new SaslEncodingException("Not enough bytes for a scalar in buffer");
}
if (in.available() < count) {
throw new SaslEncodingException("Illegal SASL scalar encoding");
}
byte[] element = new byte[count];
in.read(element);
long result = 0L;
for (int i = 0; i < count; i++) {
result <<= 8;
result |= element[i] & 0xFFL;
}
return result;
}
/**
* <p>Decodes a SASL OS from the current buffer.</p>
*
* @return a native representation of a SASL OS.
* @throws SaslEncodingException if an encoding exception occurs during the
* operation.
* @throws IOException if any other I/O exception occurs during the operation.
*/
public byte[] getOS() throws IOException {
if (!hasMoreElements()) {
throw new SaslEncodingException("Not enough bytes for an octet-sequence in buffer");
}
final int elementLength = in.read();
if (elementLength > Registry.SASL_ONE_BYTE_MAX_LIMIT) {
throw new SaslEncodingException("SASL octet-sequence size limit exceeded");
}
if (in.available() < elementLength) {
throw new SaslEncodingException("Illegal SASL octet-sequence encoding");
}
byte[] result = new byte[elementLength];
in.read(result);
return result;
}
/**
* <p>Decodes a SASL EOS from the current buffer.</p>
*
* @return a native representation of a SASL EOS.
* @throws SaslEncodingException if an encoding exception occurs during the
* operation.
* @throws IOException if any other I/O exception occurs during the operation.
*/
public byte[] getEOS() throws IOException {
if (in.available() < 2) {
throw new SaslEncodingException(
"Not enough bytes for an extended octet-sequence in buffer");
}
byte[] elementLengthBytes = new byte[2];
in.read(elementLengthBytes);
final int elementLength = twoBytesToLength(elementLengthBytes);
if (in.available() < elementLength) {
throw new SaslEncodingException("Illegal SASL extended octet-sequence encoding");
}
byte[] result = new byte[elementLength];
in.read(result);
return result;
}
/**
* <p>Decodes a SASL MPI from the current buffer.</p>
*
* @return a native representation of a SASL MPI.
* @throws SaslEncodingException if an encoding exception occurs during the
* operation.
* @throws IOException if any other I/O exception occurs during the operation.
*/
public BigInteger getMPI() throws IOException {
if (in.available() < 2) {
throw new SaslEncodingException("Not enough bytes for an MPI in buffer");
}
byte[] elementLengthBytes = new byte[2];
in.read(elementLengthBytes);
final int elementLength = twoBytesToLength(elementLengthBytes);
if (in.available() < elementLength) {
throw new SaslEncodingException("Illegal SASL multi-precision integer encoding");
}
byte[] element = new byte[elementLength];
in.read(element);
return new BigInteger(1, element);
}
/**
* <p>Decodes a SASL Text from the current buffer.</p>
*
* @return a native representation of a SASL Text.
* @throws SaslEncodingException if an encoding exception occurs during the
* operation.
* @throws SaslEncodingException if the UTF-8 character encoding is not
* supported on this platform.
* @throws IOException if any other I/O exception occurs during the operation.
*/
public String getText() throws IOException {
if (in.available() < 2) {
throw new SaslEncodingException("Not enough bytes for a text in buffer");
}
byte[] elementLengthBytes = new byte[2];
in.read(elementLengthBytes);
final int elementLength = twoBytesToLength(elementLengthBytes);
if (in.available() < elementLength) {
throw new SaslEncodingException("Illegal SASL text encoding");
}
byte[] element = new byte[elementLength];
in.read(element);
return new String(element, "UTF8");
}
}