358 lines
12 KiB
Java
358 lines
12 KiB
Java
/*
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* Copyright (c) 1998, 2012, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.security.util;
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import java.io.IOException;
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import java.util.ArrayList;
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/**
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* A package private utility class to convert indefinite length DER
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* encoded byte arrays to definite length DER encoded byte arrays.
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*
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* This assumes that the basic data structure is "tag, length, value"
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* triplet. In the case where the length is "indefinite", terminating
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* end-of-contents bytes are expected.
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*
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* @author Hemma Prafullchandra
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*/
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class DerIndefLenConverter {
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private static final int TAG_MASK = 0x1f; // bits 5-1
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private static final int FORM_MASK = 0x20; // bits 6
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private static final int CLASS_MASK = 0xC0; // bits 8 and 7
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private static final int LEN_LONG = 0x80; // bit 8 set
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private static final int LEN_MASK = 0x7f; // bits 7 - 1
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private static final int SKIP_EOC_BYTES = 2;
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private byte[] data, newData;
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private int newDataPos, dataPos, dataSize, index;
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private int unresolved = 0;
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private ArrayList<Object> ndefsList = new ArrayList<Object>();
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private int numOfTotalLenBytes = 0;
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private boolean isEOC(int tag) {
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return (((tag & TAG_MASK) == 0x00) && // EOC
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((tag & FORM_MASK) == 0x00) && // primitive
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((tag & CLASS_MASK) == 0x00)); // universal
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}
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// if bit 8 is set then it implies either indefinite length or long form
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static boolean isLongForm(int lengthByte) {
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return ((lengthByte & LEN_LONG) == LEN_LONG);
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}
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/*
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* Default package private constructor
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*/
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DerIndefLenConverter() { }
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/**
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* Checks whether the given length byte is of the form
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* <em>Indefinite</em>.
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*
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* @param lengthByte the length byte from a DER encoded
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* object.
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* @return true if the byte is of Indefinite form otherwise
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* returns false.
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*/
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static boolean isIndefinite(int lengthByte) {
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return (isLongForm(lengthByte) && ((lengthByte & LEN_MASK) == 0));
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}
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/**
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* Parse the tag and if it is an end-of-contents tag then
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* add the current position to the <code>eocList</code> vector.
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*/
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private void parseTag() throws IOException {
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if (dataPos == dataSize)
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return;
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if (isEOC(data[dataPos]) && (data[dataPos + 1] == 0)) {
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int numOfEncapsulatedLenBytes = 0;
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Object elem = null;
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int index;
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for (index = ndefsList.size()-1; index >= 0; index--) {
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// Determine the first element in the vector that does not
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// have a matching EOC
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elem = ndefsList.get(index);
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if (elem instanceof Integer) {
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break;
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} else {
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numOfEncapsulatedLenBytes += ((byte[])elem).length - 3;
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}
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}
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if (index < 0) {
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throw new IOException("EOC does not have matching " +
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"indefinite-length tag");
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}
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int sectionLen = dataPos - ((Integer)elem).intValue() +
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numOfEncapsulatedLenBytes;
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byte[] sectionLenBytes = getLengthBytes(sectionLen);
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ndefsList.set(index, sectionLenBytes);
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unresolved--;
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// Add the number of bytes required to represent this section
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// to the total number of length bytes,
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// and subtract the indefinite-length tag (1 byte) and
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// EOC bytes (2 bytes) for this section
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numOfTotalLenBytes += (sectionLenBytes.length - 3);
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}
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dataPos++;
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}
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/**
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* Write the tag and if it is an end-of-contents tag
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* then skip the tag and its 1 byte length of zero.
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*/
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private void writeTag() {
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if (dataPos == dataSize)
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return;
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int tag = data[dataPos++];
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if (isEOC(tag) && (data[dataPos] == 0)) {
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dataPos++; // skip length
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writeTag();
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} else
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newData[newDataPos++] = (byte)tag;
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}
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/**
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* Parse the length and if it is an indefinite length then add
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* the current position to the <code>ndefsList</code> vector.
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*/
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private int parseLength() throws IOException {
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int curLen = 0;
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if (dataPos == dataSize)
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return curLen;
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int lenByte = data[dataPos++] & 0xff;
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if (isIndefinite(lenByte)) {
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ndefsList.add(new Integer(dataPos));
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unresolved++;
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return curLen;
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}
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if (isLongForm(lenByte)) {
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lenByte &= LEN_MASK;
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if (lenByte > 4) {
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throw new IOException("Too much data");
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}
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if ((dataSize - dataPos) < (lenByte + 1)) {
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throw new IOException("Too little data");
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}
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for (int i = 0; i < lenByte; i++) {
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curLen = (curLen << 8) + (data[dataPos++] & 0xff);
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}
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if (curLen < 0) {
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throw new IOException("Invalid length bytes");
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}
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} else {
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curLen = (lenByte & LEN_MASK);
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}
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return curLen;
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}
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/**
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* Write the length and if it is an indefinite length
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* then calculate the definite length from the positions
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* of the indefinite length and its matching EOC terminator.
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* Then, write the value.
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*/
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private void writeLengthAndValue() throws IOException {
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if (dataPos == dataSize)
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return;
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int curLen = 0;
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int lenByte = data[dataPos++] & 0xff;
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if (isIndefinite(lenByte)) {
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byte[] lenBytes = (byte[])ndefsList.get(index++);
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System.arraycopy(lenBytes, 0, newData, newDataPos,
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lenBytes.length);
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newDataPos += lenBytes.length;
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return;
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}
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if (isLongForm(lenByte)) {
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lenByte &= LEN_MASK;
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for (int i = 0; i < lenByte; i++) {
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curLen = (curLen << 8) + (data[dataPos++] & 0xff);
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}
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if (curLen < 0) {
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throw new IOException("Invalid length bytes");
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}
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} else {
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curLen = (lenByte & LEN_MASK);
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}
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writeLength(curLen);
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writeValue(curLen);
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}
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private void writeLength(int curLen) {
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if (curLen < 128) {
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newData[newDataPos++] = (byte)curLen;
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} else if (curLen < (1 << 8)) {
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newData[newDataPos++] = (byte)0x81;
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newData[newDataPos++] = (byte)curLen;
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} else if (curLen < (1 << 16)) {
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newData[newDataPos++] = (byte)0x82;
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newData[newDataPos++] = (byte)(curLen >> 8);
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newData[newDataPos++] = (byte)curLen;
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} else if (curLen < (1 << 24)) {
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newData[newDataPos++] = (byte)0x83;
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newData[newDataPos++] = (byte)(curLen >> 16);
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newData[newDataPos++] = (byte)(curLen >> 8);
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newData[newDataPos++] = (byte)curLen;
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} else {
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newData[newDataPos++] = (byte)0x84;
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newData[newDataPos++] = (byte)(curLen >> 24);
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newData[newDataPos++] = (byte)(curLen >> 16);
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newData[newDataPos++] = (byte)(curLen >> 8);
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newData[newDataPos++] = (byte)curLen;
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}
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}
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private byte[] getLengthBytes(int curLen) {
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byte[] lenBytes;
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int index = 0;
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if (curLen < 128) {
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lenBytes = new byte[1];
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lenBytes[index++] = (byte)curLen;
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} else if (curLen < (1 << 8)) {
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lenBytes = new byte[2];
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lenBytes[index++] = (byte)0x81;
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lenBytes[index++] = (byte)curLen;
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} else if (curLen < (1 << 16)) {
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lenBytes = new byte[3];
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lenBytes[index++] = (byte)0x82;
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lenBytes[index++] = (byte)(curLen >> 8);
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lenBytes[index++] = (byte)curLen;
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} else if (curLen < (1 << 24)) {
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lenBytes = new byte[4];
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lenBytes[index++] = (byte)0x83;
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lenBytes[index++] = (byte)(curLen >> 16);
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lenBytes[index++] = (byte)(curLen >> 8);
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lenBytes[index++] = (byte)curLen;
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} else {
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lenBytes = new byte[5];
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lenBytes[index++] = (byte)0x84;
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lenBytes[index++] = (byte)(curLen >> 24);
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lenBytes[index++] = (byte)(curLen >> 16);
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lenBytes[index++] = (byte)(curLen >> 8);
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lenBytes[index++] = (byte)curLen;
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}
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return lenBytes;
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}
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// Returns the number of bytes needed to represent the given length
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// in ASN.1 notation
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private int getNumOfLenBytes(int len) {
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int numOfLenBytes = 0;
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if (len < 128) {
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numOfLenBytes = 1;
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} else if (len < (1 << 8)) {
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numOfLenBytes = 2;
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} else if (len < (1 << 16)) {
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numOfLenBytes = 3;
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} else if (len < (1 << 24)) {
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numOfLenBytes = 4;
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} else {
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numOfLenBytes = 5;
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}
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return numOfLenBytes;
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}
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/**
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* Parse the value;
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*/
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private void parseValue(int curLen) {
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dataPos += curLen;
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}
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/**
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* Write the value;
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*/
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private void writeValue(int curLen) {
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for (int i=0; i < curLen; i++)
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newData[newDataPos++] = data[dataPos++];
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}
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/**
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* Converts a indefinite length DER encoded byte array to
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* a definte length DER encoding.
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*
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* @param indefData the byte array holding the indefinite
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* length encoding.
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* @return the byte array containing the definite length
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* DER encoding.
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* @exception IOException on parsing or re-writing errors.
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*/
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byte[] convert(byte[] indefData) throws IOException {
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data = indefData;
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dataPos=0; index=0;
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dataSize = data.length;
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int len=0;
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int unused = 0;
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// parse and set up the vectors of all the indefinite-lengths
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while (dataPos < dataSize) {
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parseTag();
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len = parseLength();
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parseValue(len);
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if (unresolved == 0) {
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unused = dataSize - dataPos;
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dataSize = dataPos;
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break;
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}
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}
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if (unresolved != 0) {
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throw new IOException("not all indef len BER resolved");
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}
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newData = new byte[dataSize + numOfTotalLenBytes + unused];
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dataPos=0; newDataPos=0; index=0;
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// write out the new byte array replacing all the indefinite-lengths
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// and EOCs
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while (dataPos < dataSize) {
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writeTag();
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writeLengthAndValue();
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}
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System.arraycopy(indefData, dataSize,
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newData, dataSize + numOfTotalLenBytes, unused);
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return newData;
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}
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}
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