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sun.security.util.DerIndefLenConverter Maven / Gradle / Ivy
/*
* Copyright (c) 1998, 2021, 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.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
/**
* A package private utility class to convert indefinite length BER
* encoded byte arrays to definite length DER encoded byte arrays.
*
* Note: This class only substitute indefinite length octets to definite
* length octets. It does not update the contents even if they are not DER.
*
* 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 LEN_LONG = 0x80; // bit 8 set
private static final int LEN_MASK = 0x7f; // bits 7 - 1
private byte[] data, newData;
private int newDataPos, dataPos, dataSize, index;
private int unresolved = 0;
// A list to store each indefinite length occurrence. Whenever an indef
// length is seen, the position after the 0x80 byte is appended to the
// list as an integer. Whenever its matching EOC is seen, we know the
// actual length and the position value is substituted with a calculated
// length octets. At the end, the new DER encoding is a concatenation of
// all existing tags, existing definite length octets, existing contents,
// and the newly created definte length octets in this list.
private ArrayList ndefsList = new ArrayList();
// Length of extra bytes needed to convert indefinite encoding to definite.
// For each resolved indefinite length encoding, the starting 0x80 byte
// and the ending 00 00 bytes will be removed and a new definite length
// octets will be added. This value might be positive or negative.
private int numOfTotalLenBytes = 0;
private static boolean isEOC(byte[] data, int pos) {
return data[pos] == 0 && data[pos + 1] == 0;
}
// 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);
}
/*
* Private constructor
*/
private DerIndefLenConverter() { }
/**
* Checks whether the given length byte is of the form
* Indefinite .
*
* @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));
}
/**
* Consumes the tag at {@code dataPos}.
*
* If it is EOC then replace the matching start position (i.e. the previous
* {@code dataPos} where an indefinite length was found by #parseLength)
* in {@code ndefsList} with a length octets for this section.
*/
private void parseTag() throws IOException {
if (isEOC(data, dataPos)) {
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 {
// For each existing converted part, 3 bytes (80 at the
// beginning and 00 00 at the end) are removed and a
// new length octets is added.
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);
assert unresolved > 0;
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;
}
assert dataPos + 1 < dataSize;
if (isEOC(data, dataPos)) {
dataPos += 2; // skip tag and length
writeTag();
} else {
newData[newDataPos++] = data[dataPos++];
}
}
/**
* Parse the length octets started at {@code dataPos}. After this method
* is called, {@code dataPos} is placed after the length octets except
* -1 is returned.
*
* @return a) the length of definite length data next
* b) -1, if it is a definite length data next but the length
* octets is not complete to determine the actual length
* c) 0, if it is an indefinite length. Also, append the current
* position to the {@code ndefsList} vector.
* @throws IOException if invalid data is read
*/
private int parseLength() throws IOException {
if (dataPos == dataSize) {
return 0;
}
int lenByte = data[dataPos++] & 0xff;
if (isIndefinite(lenByte)) {
ndefsList.add(dataPos);
unresolved++;
return 0;
}
int curLen = 0;
if (isLongForm(lenByte)) {
lenByte &= LEN_MASK;
if (lenByte > 4) {
throw new IOException("Too much data");
}
if ((dataSize - dataPos) < (lenByte + 1)) {
return -1;
}
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 value.
*
* If it was definite length, just re-write the length and copy the value.
* If it was an indefinite length, copy the precalculated definite octets
* from {@code ndefsList}. There is no values here because they will be
* sub-encodings of a constructed encoding.
*/
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;
} else {
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;
}
/**
* Write the value;
*/
private void writeValue(int curLen) {
System.arraycopy(data, dataPos, newData, newDataPos, curLen);
dataPos += curLen;
newDataPos += curLen;
}
/**
* 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, or null if there is not enough data.
* @exception IOException on parsing or re-writing errors.
*/
byte[] convertBytes(byte[] indefData) throws IOException {
data = indefData;
dataPos = 0;
dataSize = data.length;
// parse and set up the vectors of all the indefinite-lengths
while (dataPos < dataSize) {
if (dataPos + 2 > dataSize) {
// There should be at least one tag and one length
return null;
}
parseTag();
int len = parseLength();
if (len < 0) {
return null;
}
dataPos += len;
if (dataPos < 0) {
// overflow
throw new IOException("Data overflow");
}
if (unresolved == 0) {
assert !ndefsList.isEmpty() && ndefsList.get(0) instanceof byte[];
break;
}
}
if (unresolved != 0) {
return null;
}
int unused = dataSize - dataPos;
assert unused >= 0;
dataSize = dataPos;
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;
}
/**
* Read the input stream into a DER byte array. If an indef len BER is
* not resolved this method will try to read more data until EOF is reached.
* This may block.
*
* @param in the input stream with tag and lenByte already read
* @param tag the tag to remember
* @return a DER byte array
* @throws IOException if not all indef len BER
* can be resolved or another I/O error happens
*/
public static byte[] convertStream(InputStream in, byte tag)
throws IOException {
int offset = 2; // for tag and length bytes
int readLen = in.available();
byte[] indefData = new byte[readLen + offset];
indefData[0] = tag;
indefData[1] = (byte)0x80;
while (true) {
int bytesRead = in.readNBytes(indefData, offset, readLen);
if (bytesRead != readLen) {
readLen = bytesRead;
indefData = Arrays.copyOf(indefData, offset + bytesRead);
}
DerIndefLenConverter derIn = new DerIndefLenConverter();
byte[] result = derIn.convertBytes(indefData);
if (result == null) {
int next = in.read(); // This could block, but we need more
if (next == -1) {
throw new IOException("not enough data to resolve indef len BER");
}
int more = in.available();
// expand array to include next and more
indefData = Arrays.copyOf(indefData, offset + readLen + 1 + more);
indefData[offset + readLen] = (byte)next;
offset = offset + readLen + 1;
readLen = more;
} else {
return result;
}
}
}
}
