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	/*
	* Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package com.sun.jndi.ldap;

	import java.io.UnsupportedEncodingException;

	/**
	* A BER encoder.
	*
	* @author Jagane Sundar
	* @author Scott Seligman
	* @author Vincent Ryan
	*/
	public final class BerEncoder extends Ber {

	private int curSeqIndex;
	private int seqOffset[];
	private static final int INITIAL_SEQUENCES = 16;
	private static final int DEFAULT_BUFSIZE = 1024;

	// When buf is full, expand its size by the following factor.
	private static final int BUF_GROWTH_FACTOR = 8;

	/**
	* Creates a BER buffer for encoding.
	*/
	public BerEncoder() {
	this(DEFAULT_BUFSIZE);
	}

	/**
	* Creates a BER buffer of a specified size for encoding.
	* Specify the initial bufsize. Buffer will be expanded as needed.
	* @param bufsize The number of bytes for the buffer.
	*/
	public BerEncoder(int bufsize) {
	buf = new byte[bufsize];
	this.bufsize = bufsize;
	offset = 0;

	seqOffset = new int[INITIAL_SEQUENCES];
	curSeqIndex = 0;
	}

	/**
	* Resets encoder to state when newly constructed. Zeros out
	* internal data structures.
	*/
	public void reset() {
	while (offset > 0) {
	buf[--offset] = 0;
	}
	while (curSeqIndex > 0) {
	seqOffset[--curSeqIndex] = 0;
	}
	}

	// ------------------ Accessor methods ------------

	/**
	* Gets the number of encoded bytes in this BER buffer.
	*/
	public int getDataLen() {
	return offset;
	}

	/**
	* Gets the buffer that contains the BER encoding. Throws an
	* exception if unmatched beginSeq() and endSeq() pairs were
	* encountered. Not entire buffer contains encoded bytes.
	* Use getDataLen() to determine number of encoded bytes.
	* Use getBuffer(true) to get rid of excess bytes in array.
	* @throws IllegalStateException If buffer contains unbalanced sequence.
	*/
	public byte[] getBuf() {
	if (curSeqIndex != 0) {
	throw new IllegalStateException("BER encode error: Unbalanced SEQUENCEs.");
	}
	return buf; // shared buffer, be careful to use this method.
	}

	/**
	* Gets the buffer that contains the BER encoding, trimming unused bytes.
	*
	* @throws IllegalStateException If buffer contains unbalanced sequence.
	*/
	public byte[] getTrimmedBuf() {
	int len = getDataLen();
	byte[] trimBuf = new byte[len];

	System.arraycopy(getBuf(), 0, trimBuf, 0, len);
	return trimBuf;
	}

	// -------------- encoding methods -------------

	/**
	* Begin encoding a sequence with a tag.
	*/
	public void beginSeq(int tag) {

	// Double the size of the SEQUENCE array if it overflows
	if (curSeqIndex >= seqOffset.length) {
	int[] seqOffsetTmp = new int[seqOffset.length * 2];

	for (int i = 0; i < seqOffset.length; i++) {
	seqOffsetTmp[i] = seqOffset[i];
	}
	seqOffset = seqOffsetTmp;
	}

	encodeByte(tag);
	seqOffset[curSeqIndex] = offset;

	// Save space for sequence length.
	// %%% Currently we save enough space for sequences up to 64k.
	// For larger sequences we'll need to shift the data to the right
	// in endSeq(). If we could instead pad the length field with
	// zeros, it would be a big win.
	ensureFreeBytes(3);
	offset += 3;

	curSeqIndex++;
	}

	/**
	* Terminate a BER sequence.
	*/
	public void endSeq() throws EncodeException {
	curSeqIndex--;
	if (curSeqIndex < 0) {
	throw new IllegalStateException("BER encode error: Unbalanced SEQUENCEs.");
	}

	int start = seqOffset[curSeqIndex] + 3; // index beyond length field
	int len = offset - start;

	if (len <= 0x7f) {
	shiftSeqData(start, len, -2);
	buf[seqOffset[curSeqIndex]] = (byte) len;
	} else if (len <= 0xff) {
	shiftSeqData(start, len, -1);
	buf[seqOffset[curSeqIndex]] = (byte) 0x81;
	buf[seqOffset[curSeqIndex] + 1] = (byte) len;
	} else if (len <= 0xffff) {
	buf[seqOffset[curSeqIndex]] = (byte) 0x82;
	buf[seqOffset[curSeqIndex] + 1] = (byte) (len >> 8);
	buf[seqOffset[curSeqIndex] + 2] = (byte) len;
	} else if (len <= 0xffffff) {
	shiftSeqData(start, len, 1);
	buf[seqOffset[curSeqIndex]] = (byte) 0x83;
	buf[seqOffset[curSeqIndex] + 1] = (byte) (len >> 16);
	buf[seqOffset[curSeqIndex] + 2] = (byte) (len >> 8);
	buf[seqOffset[curSeqIndex] + 3] = (byte) len;
	} else {
	throw new EncodeException("SEQUENCE too long");
	}
	}

	/**
	* Shifts contents of buf in the range [start,start+len) a specified amount.
	* Positive shift value means shift to the right.
	*/
	private void shiftSeqData(int start, int len, int shift) {
	if (shift > 0) {
	ensureFreeBytes(shift);
	}
	System.arraycopy(buf, start, buf, start + shift, len);
	offset += shift;
	}

	/**
	* Encode a single byte.
	*/
	public void encodeByte(int b) {
	ensureFreeBytes(1);
	buf[offset++] = (byte) b;
	}

	/*
	private void deleteByte() {
	offset--;
	}
	*/


	/*
	* Encodes an int.
	*<blockquote><pre>
	* BER integer ::= 0x02 berlength byte {byte}*
	*</pre></blockquote>
	*/
	public void encodeInt(int i) {
	encodeInt(i, 0x02);
	}

	/**
	* Encodes an int and a tag.
	*<blockquote><pre>
	* BER integer w tag ::= tag berlength byte {byte}*
	*</pre></blockquote>
	*/
	public void encodeInt(int i, int tag) {
	int mask = 0xff800000;
	int intsize = 4;

	while( (((i & mask) == 0) \|\| ((i & mask) == mask)) && (intsize > 1) ) {
	intsize--;
	i <<= 8;
	}

	encodeInt(i, tag, intsize);
	}

	//
	// encodes an int using numbytes for the actual encoding.
	//
	private void encodeInt(int i, int tag, int intsize) {

	//
	// integer ::= 0x02 asnlength byte {byte}*
	//

	if (intsize > 4) {
	throw new IllegalArgumentException("BER encode error: INTEGER too long.");
	}

	ensureFreeBytes(2 + intsize);

	buf[offset++] = (byte) tag;
	buf[offset++] = (byte) intsize;

	int mask = 0xff000000;

	while (intsize-- > 0) {
	buf[offset++] = (byte) ((i & mask) >> 24);
	i <<= 8;
	}
	}

	/**
	* Encodes a boolean.
	*<blockquote><pre>
	* BER boolean ::= 0x01 0x01 {0xff\|0x00}
	*</pre></blockquote>
	*/
	public void encodeBoolean(boolean b) {
	encodeBoolean(b, ASN_BOOLEAN);
	}


	/**
	* Encodes a boolean and a tag
	*<blockquote><pre>
	* BER boolean w TAG ::= tag 0x01 {0xff\|0x00}
	*</pre></blockquote>
	*/
	public void encodeBoolean(boolean b, int tag) {
	ensureFreeBytes(3);

	buf[offset++] = (byte) tag;
	buf[offset++] = 0x01;
	buf[offset++] = b ? (byte) 0xff : (byte) 0x00;
	}

	/**
	* Encodes a string.
	*<blockquote><pre>
	* BER string ::= 0x04 strlen byte1 byte2...
	*</pre></blockquote>
	* The string is converted into bytes using UTF-8 or ISO-Latin-1.
	*/
	public void encodeString(String str, boolean encodeUTF8)
	throws EncodeException {
	encodeString(str, ASN_OCTET_STR, encodeUTF8);
	}

	/**
	* Encodes a string and a tag.
	*<blockquote><pre>
	* BER string w TAG ::= tag strlen byte1 byte2...
	*</pre></blockquote>
	*/
	public void encodeString(String str, int tag, boolean encodeUTF8)
	throws EncodeException {

	encodeByte(tag);

	int i = 0;
	int count;
	byte[] bytes = null;

	if (str == null) {
	count = 0;
	} else if (encodeUTF8) {
	try {
	bytes = str.getBytes("UTF8");
	count = bytes.length;
	} catch (UnsupportedEncodingException e) {
	throw new EncodeException("UTF8 not available on platform");
	}
	} else {
	try {
	bytes = str.getBytes("8859_1");
	count = bytes.length;
	} catch (UnsupportedEncodingException e) {
	throw new EncodeException("8859_1 not available on platform");
	}
	}

	encodeLength(count);

	ensureFreeBytes(count);
	while (i < count) {
	buf[offset++] = bytes[i++];
	}
	}

	/**
	* Encodes a portion of an octet string and a tag.
	*/
	public void encodeOctetString(byte tb[], int tag, int tboffset, int length)
	throws EncodeException {

	encodeByte(tag);
	encodeLength(length);

	if (length > 0) {
	ensureFreeBytes(length);
	System.arraycopy(tb, tboffset, buf, offset, length);
	offset += length;
	}
	}

	/**
	* Encodes an octet string and a tag.
	*/
	public void encodeOctetString(byte tb[], int tag) throws EncodeException {
	encodeOctetString(tb, tag, 0, tb.length);
	}

	private void encodeLength(int len) throws EncodeException {
	ensureFreeBytes(4); // worst case

	if (len < 128) {
	buf[offset++] = (byte) len;
	} else if (len <= 0xff) {
	buf[offset++] = (byte) 0x81;
	buf[offset++] = (byte) len;
	} else if (len <= 0xffff) {
	buf[offset++] = (byte) 0x82;
	buf[offset++] = (byte) (len >> 8);
	buf[offset++] = (byte) (len & 0xff);
	} else if (len <= 0xffffff) {
	buf[offset++] = (byte) 0x83;
	buf[offset++] = (byte) (len >> 16);
	buf[offset++] = (byte) (len >> 8);
	buf[offset++] = (byte) (len & 0xff);
	} else {
	throw new EncodeException("string too long");
	}
	}

	/**
	* Encodes an array of strings.
	*/
	public void encodeStringArray(String strs[], boolean encodeUTF8)
	throws EncodeException {
	if (strs == null)
	return;
	for (int i = 0; i < strs.length; i++) {
	encodeString(strs[i], encodeUTF8);
	}
	}
	/*
	private void encodeNull() {

	//
	// NULL ::= 0x05 0x00
	//
	encodeByte(0x05);
	encodeByte(0x00);
	}
	*/

	/**
	* Ensures that there are at least "len" unused bytes in "buf".
	* When more space is needed "buf" is expanded by a factor of
	* BUF_GROWTH_FACTOR, then "len" bytes are added if "buf" still
	* isn't large enough.
	*/
	private void ensureFreeBytes(int len) {
	if (bufsize - offset < len) {
	int newsize = bufsize * BUF_GROWTH_FACTOR;
	if (newsize - offset < len) {
	newsize += len;
	}
	byte newbuf[] = new byte[newsize];
	// Only copy bytes in the range [0, offset)
	System.arraycopy(buf, 0, newbuf, 0, offset);

	buf = newbuf;
	bufsize = newsize;
	}
	}
	}

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