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	/*
	* Copyright (c) 1998, 2012, 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 sun.security.util;

	import java.io.IOException;
	import java.util.ArrayList;

	/**
	* A package private utility class to convert indefinite length DER
	* encoded byte arrays to definite length DER encoded byte arrays.
	*
	* This assumes that the basic data structure is "tag, length, value"
	* triplet. In the case where the length is "indefinite", terminating
	* end-of-contents bytes are expected.
	*
	* @author Hemma Prafullchandra
	*/
	class DerIndefLenConverter {

	private static final int TAG_MASK = 0x1f; // bits 5-1
	private static final int FORM_MASK = 0x20; // bits 6
	private static final int CLASS_MASK = 0xC0; // bits 8 and 7

	private static final int LEN_LONG = 0x80; // bit 8 set
	private static final int LEN_MASK = 0x7f; // bits 7 - 1
	private static final int SKIP_EOC_BYTES = 2;

	private byte[] data, newData;
	private int newDataPos, dataPos, dataSize, index;
	private int unresolved = 0;

	private ArrayList<Object> ndefsList = new ArrayList<Object>();

	private int numOfTotalLenBytes = 0;

	private boolean isEOC(int tag) {
	return (((tag & TAG_MASK) == 0x00) && // EOC
	((tag & FORM_MASK) == 0x00) && // primitive
	((tag & CLASS_MASK) == 0x00)); // universal
	}

	// if bit 8 is set then it implies either indefinite length or long form
	static boolean isLongForm(int lengthByte) {
	return ((lengthByte & LEN_LONG) == LEN_LONG);
	}

	/*
	* Default package private constructor
	*/
	DerIndefLenConverter() { }

	/**
	* Checks whether the given length byte is of the form
	* <em>Indefinite</em>.
	*
	* @param lengthByte the length byte from a DER encoded
	* object.
	* @return true if the byte is of Indefinite form otherwise
	* returns false.
	*/
	static boolean isIndefinite(int lengthByte) {
	return (isLongForm(lengthByte) && ((lengthByte & LEN_MASK) == 0));
	}

	/**
	* Parse the tag and if it is an end-of-contents tag then
	* add the current position to the <code>eocList</code> vector.
	*/
	private void parseTag() throws IOException {
	if (dataPos == dataSize)
	return;
	if (isEOC(data[dataPos]) && (data[dataPos + 1] == 0)) {
	int numOfEncapsulatedLenBytes = 0;
	Object elem = null;
	int index;
	for (index = ndefsList.size()-1; index >= 0; index--) {
	// Determine the first element in the vector that does not
	// have a matching EOC
	elem = ndefsList.get(index);
	if (elem instanceof Integer) {
	break;
	} else {
	numOfEncapsulatedLenBytes += ((byte[])elem).length - 3;
	}
	}
	if (index < 0) {
	throw new IOException("EOC does not have matching " +
	"indefinite-length tag");
	}
	int sectionLen = dataPos - ((Integer)elem).intValue() +
	numOfEncapsulatedLenBytes;
	byte[] sectionLenBytes = getLengthBytes(sectionLen);
	ndefsList.set(index, sectionLenBytes);
	unresolved--;

	// Add the number of bytes required to represent this section
	// to the total number of length bytes,
	// and subtract the indefinite-length tag (1 byte) and
	// EOC bytes (2 bytes) for this section
	numOfTotalLenBytes += (sectionLenBytes.length - 3);
	}
	dataPos++;
	}

	/**
	* Write the tag and if it is an end-of-contents tag
	* then skip the tag and its 1 byte length of zero.
	*/
	private void writeTag() {
	if (dataPos == dataSize)
	return;
	int tag = data[dataPos++];
	if (isEOC(tag) && (data[dataPos] == 0)) {
	dataPos++; // skip length
	writeTag();
	} else
	newData[newDataPos++] = (byte)tag;
	}

	/**
	* Parse the length and if it is an indefinite length then add
	* the current position to the <code>ndefsList</code> vector.
	*/
	private int parseLength() throws IOException {
	int curLen = 0;
	if (dataPos == dataSize)
	return curLen;
	int lenByte = data[dataPos++] & 0xff;
	if (isIndefinite(lenByte)) {
	ndefsList.add(dataPos);
	unresolved++;
	return curLen;
	}
	if (isLongForm(lenByte)) {
	lenByte &= LEN_MASK;
	if (lenByte > 4) {
	throw new IOException("Too much data");
	}
	if ((dataSize - dataPos) < (lenByte + 1)) {
	throw new IOException("Too little data");
	}
	for (int i = 0; i < lenByte; i++) {
	curLen = (curLen << 8) + (data[dataPos++] & 0xff);
	}
	if (curLen < 0) {
	throw new IOException("Invalid length bytes");
	}
	} else {
	curLen = (lenByte & LEN_MASK);
	}
	return curLen;
	}

	/**
	* Write the length and if it is an indefinite length
	* then calculate the definite length from the positions
	* of the indefinite length and its matching EOC terminator.
	* Then, write the value.
	*/
	private void writeLengthAndValue() throws IOException {
	if (dataPos == dataSize)
	return;
	int curLen = 0;
	int lenByte = data[dataPos++] & 0xff;
	if (isIndefinite(lenByte)) {
	byte[] lenBytes = (byte[])ndefsList.get(index++);
	System.arraycopy(lenBytes, 0, newData, newDataPos,
	lenBytes.length);
	newDataPos += lenBytes.length;
	return;
	}
	if (isLongForm(lenByte)) {
	lenByte &= LEN_MASK;
	for (int i = 0; i < lenByte; i++) {
	curLen = (curLen << 8) + (data[dataPos++] & 0xff);
	}
	if (curLen < 0) {
	throw new IOException("Invalid length bytes");
	}
	} else {
	curLen = (lenByte & LEN_MASK);
	}
	writeLength(curLen);
	writeValue(curLen);
	}

	private void writeLength(int curLen) {
	if (curLen < 128) {
	newData[newDataPos++] = (byte)curLen;

	} else if (curLen < (1 << 8)) {
	newData[newDataPos++] = (byte)0x81;
	newData[newDataPos++] = (byte)curLen;

	} else if (curLen < (1 << 16)) {
	newData[newDataPos++] = (byte)0x82;
	newData[newDataPos++] = (byte)(curLen >> 8);
	newData[newDataPos++] = (byte)curLen;

	} else if (curLen < (1 << 24)) {
	newData[newDataPos++] = (byte)0x83;
	newData[newDataPos++] = (byte)(curLen >> 16);
	newData[newDataPos++] = (byte)(curLen >> 8);
	newData[newDataPos++] = (byte)curLen;

	} else {
	newData[newDataPos++] = (byte)0x84;
	newData[newDataPos++] = (byte)(curLen >> 24);
	newData[newDataPos++] = (byte)(curLen >> 16);
	newData[newDataPos++] = (byte)(curLen >> 8);
	newData[newDataPos++] = (byte)curLen;
	}
	}

	private byte[] getLengthBytes(int curLen) {
	byte[] lenBytes;
	int index = 0;

	if (curLen < 128) {
	lenBytes = new byte[1];
	lenBytes[index++] = (byte)curLen;

	} else if (curLen < (1 << 8)) {
	lenBytes = new byte[2];
	lenBytes[index++] = (byte)0x81;
	lenBytes[index++] = (byte)curLen;

	} else if (curLen < (1 << 16)) {
	lenBytes = new byte[3];
	lenBytes[index++] = (byte)0x82;
	lenBytes[index++] = (byte)(curLen >> 8);
	lenBytes[index++] = (byte)curLen;

	} else if (curLen < (1 << 24)) {
	lenBytes = new byte[4];
	lenBytes[index++] = (byte)0x83;
	lenBytes[index++] = (byte)(curLen >> 16);
	lenBytes[index++] = (byte)(curLen >> 8);
	lenBytes[index++] = (byte)curLen;

	} else {
	lenBytes = new byte[5];
	lenBytes[index++] = (byte)0x84;
	lenBytes[index++] = (byte)(curLen >> 24);
	lenBytes[index++] = (byte)(curLen >> 16);
	lenBytes[index++] = (byte)(curLen >> 8);
	lenBytes[index++] = (byte)curLen;
	}

	return lenBytes;
	}

	// Returns the number of bytes needed to represent the given length
	// in ASN.1 notation
	private int getNumOfLenBytes(int len) {
	int numOfLenBytes = 0;

	if (len < 128) {
	numOfLenBytes = 1;
	} else if (len < (1 << 8)) {
	numOfLenBytes = 2;
	} else if (len < (1 << 16)) {
	numOfLenBytes = 3;
	} else if (len < (1 << 24)) {
	numOfLenBytes = 4;
	} else {
	numOfLenBytes = 5;
	}
	return numOfLenBytes;
	}

	/**
	* Parse the value;
	*/
	private void parseValue(int curLen) {
	dataPos += curLen;
	}

	/**
	* Write the value;
	*/
	private void writeValue(int curLen) {
	for (int i=0; i < curLen; i++)
	newData[newDataPos++] = data[dataPos++];
	}

	/**
	* Converts a indefinite length DER encoded byte array to
	* a definte length DER encoding.
	*
	* @param indefData the byte array holding the indefinite
	* length encoding.
	* @return the byte array containing the definite length
	* DER encoding.
	* @exception IOException on parsing or re-writing errors.
	*/
	byte[] convert(byte[] indefData) throws IOException {
	data = indefData;
	dataPos=0; index=0;
	dataSize = data.length;
	int len=0;
	int unused = 0;

	// parse and set up the vectors of all the indefinite-lengths
	while (dataPos < dataSize) {
	parseTag();
	len = parseLength();
	parseValue(len);
	if (unresolved == 0) {
	unused = dataSize - dataPos;
	dataSize = dataPos;
	break;
	}
	}

	if (unresolved != 0) {
	throw new IOException("not all indef len BER resolved");
	}

	newData = new byte[dataSize + numOfTotalLenBytes + unused];
	dataPos=0; newDataPos=0; index=0;

	// write out the new byte array replacing all the indefinite-lengths
	// and EOCs
	while (dataPos < dataSize) {
	writeTag();
	writeLengthAndValue();
	}
	System.arraycopy(indefData, dataSize,
	newData, dataSize + numOfTotalLenBytes, unused);

	return newData;
	}
	}

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