/*
* Copyright 1998-2006 Sun Microsystems, Inc. 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. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.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 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);
// 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(new Integer(dataPos));
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);
} 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);
} 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;
// parse and set up the vectors of all the indefinite-lengths
while (dataPos < dataSize) {
parseTag();
len = parseLength();
parseValue(len);
}
newData = new byte[dataSize + numOfTotalLenBytes];
dataPos=0; newDataPos=0; index=0;
// write out the new byte array replacing all the indefinite-lengths
// and EOCs
while (dataPos < dataSize) {
writeTag();
writeLengthAndValue();
}
return newData;
}
}