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jeremybenn |
/* InputBuffer.java --
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Copyright (C) 2003, 2006 Free Software Foundation, Inc.
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This file is a part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or (at
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your option) any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
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USA
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.javax.crypto.sasl;
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import gnu.java.security.Registry;
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import java.io.ByteArrayInputStream;
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import java.io.IOException;
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import java.math.BigInteger;
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/**
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* The implementation of an incoming SASL buffer.
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* <p>
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* The data elements this class caters for are described in [1].
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* <p>
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* References:
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* <ol>
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* <li><a
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* href="http://www.ietf.org/internet-drafts/draft-burdis-cat-srp-sasl-09.txt">
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* Secure Remote Password Authentication Mechanism</a>;<br/>
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* draft-burdis-cat-srp-sasl-09,<br/> <a
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* href="mailto:keith@rucus.ru.ac.za">Keith Burdis</a> and <a
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* href="mailto:raif@forge.com.au">Raïf S. Naffah</a>.</li>
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* </ol>
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*/
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public class InputBuffer
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{
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/** The internal buffer stream containing the buffer's contents. */
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protected ByteArrayInputStream in;
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/** The length of the buffer, according to its header. */
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protected int length;
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/**
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* Constructs a SASL buffer given the buffer's encoded form, including its
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* header bytes.
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*
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* @param frame the encoded form, including the header bytes, of a SASL
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* buffer.
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* @throws SaslEncodingException if the buffer is malformed.
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*/
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public InputBuffer(byte[] frame) throws SaslEncodingException
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{
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this();
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if (frame.length < 4)
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throw new SaslEncodingException("SASL buffer header too short");
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length = (frame[0] & 0xFF) << 24
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| (frame[1] & 0xFF) << 16
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| (frame[2] & 0xFF) << 8
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| (frame[3] & 0xFF);
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if (length > Registry.SASL_BUFFER_MAX_LIMIT || length < 0)
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throw new SaslEncodingException("SASL buffer size limit exceeded");
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in = new ByteArrayInputStream(frame, 4, length);
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}
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/** Trivial private constructor for use by the class method. */
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private InputBuffer()
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{
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super();
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}
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/**
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* Returns an instance of a SASL buffer given the buffer's encoded contents,
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* excluding the buffer's header bytes.
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* <p>
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* Calls the method with the same name and three arguments as:
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* <code>getInstance(raw, 0, raw.length)</code>.
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*
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* @param raw the encoded form, excluding the header bytes, of a SASL buffer.
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* @return a new instance of {@link InputBuffer}.
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*/
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public static InputBuffer getInstance(byte[] raw)
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{
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return getInstance(raw, 0, raw.length);
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}
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/**
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* Returns an instance of a SASL buffer given the buffer's encoded contents,
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* excluding the buffer's header bytes.
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*
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* @param raw the encoded form, excluding the header bytes, of a SASL buffer.
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* @param offset offset where to start using raw bytes from.
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* @param len number of bytes to use.
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* @return a new instance of {@link InputBuffer}.
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*/
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public static InputBuffer getInstance(byte[] raw, int offset, int len)
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{
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InputBuffer result = new InputBuffer();
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result.in = new ByteArrayInputStream(raw, offset, len);
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return result;
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}
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/**
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* Converts two octets into the number that they represent.
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*
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* @param b the two octets.
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* @return the length.
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*/
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public static int twoBytesToLength(byte[] b) throws SaslEncodingException
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{
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final int result = (b[0] & 0xFF) << 8 | (b[1] & 0xFF);
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if (result > Registry.SASL_TWO_BYTE_MAX_LIMIT)
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throw new SaslEncodingException("SASL MPI/Text size limit exceeded");
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return result;
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}
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public boolean hasMoreElements()
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{
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return (in.available() > 0);
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}
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/**
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* Decodes a SASL scalar quantity, <code>count</code>-octet long, from the
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* current buffer.
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*
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* @param count the number of octets of this scalar quantity.
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* @return a native representation of a SASL scalar (unsigned integer)
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* quantity.
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* @throws SaslEncodingException if an encoding exception occurs during the
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* operation.
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* @throws IOException if any other I/O exception occurs during the operation.
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*/
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public long getScalar(int count) throws IOException
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{
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if (count < 0 || count > 4)
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throw new SaslEncodingException("Invalid SASL scalar octet count: "
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+ String.valueOf(count));
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if (! hasMoreElements())
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throw new SaslEncodingException("Not enough bytes for a scalar in buffer");
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if (in.available() < count)
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throw new SaslEncodingException("Illegal SASL scalar encoding");
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byte[] element = new byte[count];
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in.read(element);
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long result = 0L;
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for (int i = 0; i < count; i++)
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{
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result <<= 8;
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result |= element[i] & 0xFFL;
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}
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return result;
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}
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/**
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* Decodes a SASL OS from the current buffer.
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*
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* @return a native representation of a SASL OS.
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* @throws SaslEncodingException if an encoding exception occurs during the
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* operation.
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* @throws IOException if any other I/O exception occurs during the operation.
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*/
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public byte[] getOS() throws IOException
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{
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if (! hasMoreElements())
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throw new SaslEncodingException(
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"Not enough bytes for an octet-sequence in buffer");
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final int elementLength = in.read();
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if (elementLength > Registry.SASL_ONE_BYTE_MAX_LIMIT)
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throw new SaslEncodingException("SASL octet-sequence size limit exceeded");
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if (in.available() < elementLength)
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throw new SaslEncodingException("Illegal SASL octet-sequence encoding");
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byte[] result = new byte[elementLength];
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in.read(result);
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return result;
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}
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/**
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* Decodes a SASL EOS from the current buffer.
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*
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* @return a native representation of a SASL EOS.
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* @throws SaslEncodingException if an encoding exception occurs during the
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* operation.
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* @throws IOException if any other I/O exception occurs during the operation.
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*/
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public byte[] getEOS() throws IOException
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{
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if (in.available() < 2)
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throw new SaslEncodingException(
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"Not enough bytes for an extended octet-sequence in buffer");
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byte[] elementLengthBytes = new byte[2];
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in.read(elementLengthBytes);
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final int elementLength = twoBytesToLength(elementLengthBytes);
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if (in.available() < elementLength)
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throw new SaslEncodingException(
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"Illegal SASL extended octet-sequence encoding");
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byte[] result = new byte[elementLength];
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in.read(result);
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return result;
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}
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/**
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* Decodes a SASL MPI from the current buffer.
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*
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* @return a native representation of a SASL MPI.
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* @throws SaslEncodingException if an encoding exception occurs during the
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* operation.
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* @throws IOException if any other I/O exception occurs during the operation.
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*/
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public BigInteger getMPI() throws IOException
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{
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if (in.available() < 2)
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throw new SaslEncodingException("Not enough bytes for an MPI in buffer");
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byte[] elementLengthBytes = new byte[2];
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in.read(elementLengthBytes);
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final int elementLength = twoBytesToLength(elementLengthBytes);
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if (in.available() < elementLength)
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throw new SaslEncodingException(
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"Illegal SASL multi-precision integer encoding");
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byte[] element = new byte[elementLength];
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in.read(element);
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return new BigInteger(1, element);
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}
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/**
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* Decodes a SASL Text from the current buffer.
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*
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* @return a native representation of a SASL Text.
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* @throws SaslEncodingException if an encoding exception occurs during the
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* operation.
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* @throws SaslEncodingException if the UTF-8 character encoding is not
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* supported on this platform.
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* @throws IOException if any other I/O exception occurs during the operation.
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*/
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public String getText() throws IOException
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{
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if (in.available() < 2)
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throw new SaslEncodingException("Not enough bytes for a text in buffer");
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byte[] elementLengthBytes = new byte[2];
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in.read(elementLengthBytes);
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final int elementLength = twoBytesToLength(elementLengthBytes);
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if (in.available() < elementLength)
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throw new SaslEncodingException("Illegal SASL text encoding");
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byte[] element = new byte[elementLength];
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in.read(element);
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return new String(element, "UTF8");
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}
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}
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