/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.apksig.internal.asn1;
import com.android.apksig.internal.asn1.ber.BerDataValue;
import com.android.apksig.internal.asn1.ber.BerDataValueFormatException;
import com.android.apksig.internal.asn1.ber.BerDataValueReader;
import com.android.apksig.internal.asn1.ber.BerEncoding;
import com.android.apksig.internal.asn1.ber.ByteBufferBerDataValueReader;
import com.android.apksig.internal.util.ByteBufferUtils;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* Parser of ASN.1 BER-encoded structures.
*
* <p>Structure is described to the parser by providing a class annotated with {@link Asn1Class},
* containing fields annotated with {@link Asn1Field}.
*/
public final class Asn1BerParser {
private Asn1BerParser() {}
/**
* Returns the ASN.1 structure contained in the BER encoded input.
*
* @param encoded encoded input. If the decoding operation succeeds, the position of this buffer
* is advanced to the first position following the end of the consumed structure.
* @param containerClass class describing the structure of the input. The class must meet the
* following requirements:
* <ul>
* <li>The class must be annotated with {@link Asn1Class}.</li>
* <li>The class must expose a public no-arg constructor.</li>
* <li>Member fields of the class which are populated with parsed input must be
* annotated with {@link Asn1Field} and be public and non-final.</li>
* </ul>
*
* @throws Asn1DecodingException if the input could not be decoded into the specified Java
* object
*/
public static <T> T parse(ByteBuffer encoded, Class<T> containerClass)
throws Asn1DecodingException {
BerDataValue containerDataValue;
try {
containerDataValue = new ByteBufferBerDataValueReader(encoded).readDataValue();
} catch (BerDataValueFormatException e) {
throw new Asn1DecodingException("Failed to decode top-level data value", e);
}
if (containerDataValue == null) {
throw new Asn1DecodingException("Empty input");
}
return parse(containerDataValue, containerClass);
}
/**
* Returns the implicit {@code SET OF} contained in the provided ASN.1 BER input. Implicit means
* that this method does not care whether the tag number of this data structure is
* {@code SET OF} and whether the tag class is {@code UNIVERSAL}.
*
* <p>Note: The returned type is {@link List} rather than {@link java.util.Set} because ASN.1
* SET may contain duplicate elements.
*
* @param encoded encoded input. If the decoding operation succeeds, the position of this buffer
* is advanced to the first position following the end of the consumed structure.
* @param elementClass class describing the structure of the values/elements contained in this
* container. The class must meet the following requirements:
* <ul>
* <li>The class must be annotated with {@link Asn1Class}.</li>
* <li>The class must expose a public no-arg constructor.</li>
* <li>Member fields of the class which are populated with parsed input must be
* annotated with {@link Asn1Field} and be public and non-final.</li>
* </ul>
*
* @throws Asn1DecodingException if the input could not be decoded into the specified Java
* object
*/
public static <T> List<T> parseImplicitSetOf(ByteBuffer encoded, Class<T> elementClass)
throws Asn1DecodingException {
BerDataValue containerDataValue;
try {
containerDataValue = new ByteBufferBerDataValueReader(encoded).readDataValue();
} catch (BerDataValueFormatException e) {
throw new Asn1DecodingException("Failed to decode top-level data value", e);
}
if (containerDataValue == null) {
throw new Asn1DecodingException("Empty input");
}
return parseSetOf(containerDataValue, elementClass);
}
private static <T> T parse(BerDataValue container, Class<T> containerClass)
throws Asn1DecodingException {
if (container == null) {
throw new NullPointerException("container == null");
}
if (containerClass == null) {
throw new NullPointerException("containerClass == null");
}
Asn1Type dataType = getContainerAsn1Type(containerClass);
switch (dataType) {
case CHOICE:
return parseChoice(container, containerClass);
case SEQUENCE:
{
int expectedTagClass = BerEncoding.TAG_CLASS_UNIVERSAL;
int expectedTagNumber = BerEncoding.getTagNumber(dataType);
if ((container.getTagClass() != expectedTagClass)
|| (container.getTagNumber() != expectedTagNumber)) {
throw new Asn1UnexpectedTagException(
"Unexpected data value read as " + containerClass.getName()
+ ". Expected " + BerEncoding.tagClassAndNumberToString(
expectedTagClass, expectedTagNumber)
+ ", but read: " + BerEncoding.tagClassAndNumberToString(
container.getTagClass(), container.getTagNumber()));
}
return parseSequence(container, containerClass);
}
case UNENCODED_CONTAINER:
return parseSequence(container, containerClass, true);
default:
throw new Asn1DecodingException("Parsing container " + dataType + " not supported");
}
}
private static <T> T parseChoice(BerDataValue dataValue, Class<T> containerClass)
throws Asn1DecodingException {
List<AnnotatedField> fields = getAnnotatedFields(containerClass);
if (fields.isEmpty()) {
throw new Asn1DecodingException(
"No fields annotated with " + Asn1Field.class.getName()
+ " in CHOICE class " + containerClass.getName());
}
// Check that class + tagNumber don't clash between the choices
for (int i = 0; i < fields.size() - 1; i++) {
AnnotatedField f1 = fields.get(i);
int tagNumber1 = f1.getBerTagNumber();
int tagClass1 = f1.getBerTagClass();
for (int j = i + 1; j < fields.size(); j++) {
AnnotatedField f2 = fields.get(j);
int tagNumber2 = f2.getBerTagNumber();
int tagClass2 = f2.getBerTagClass();
if ((tagNumber1 == tagNumber2) && (tagClass1 == tagClass2)) {
throw new Asn1DecodingException(
"CHOICE fields are indistinguishable because they have the same tag"
+ " class and number: " + containerClass.getName()
+ "." + f1.getField().getName()
+ " and ." + f2.getField().getName());
}
}
}
// Instantiate the container object / result
T obj;
try {
obj = containerClass.getConstructor().newInstance();
} catch (IllegalArgumentException | ReflectiveOperationException e) {
throw new Asn1DecodingException("Failed to instantiate " + containerClass.getName(), e);
}
// Set the matching field's value from the data value
for (AnnotatedField field : fields) {
try {
field.setValueFrom(dataValue, obj);
return obj;
} catch (Asn1UnexpectedTagException expected) {
// not a match
}
}
throw new Asn1DecodingException(
"No options of CHOICE " + containerClass.getName() + " matched");
}
private static <T> T parseSequence(BerDataValue container, Class<T> containerClass)
throws Asn1DecodingException {
return parseSequence(container, containerClass, false);
}
private static <T> T parseSequence(BerDataValue container, Class<T> containerClass,
boolean isUnencodedContainer) throws Asn1DecodingException {
List<AnnotatedField> fields = getAnnotatedFields(containerClass);
Collections.sort(
fields, (f1, f2) -> f1.getAnnotation().index() - f2.getAnnotation().index());
// Check that there are no fields with the same index
if (fields.size() > 1) {
AnnotatedField lastField = null;
for (AnnotatedField field : fields) {
if ((lastField != null)
&& (lastField.getAnnotation().index() == field.getAnnotation().index())) {
throw new Asn1DecodingException(
"Fields have the same index: " + containerClass.getName()
+ "." + lastField.getField().getName()
+ " and ." + field.getField().getName());
}
lastField = field;
}
}
// Instantiate the container object / result
T t;
try {
t = containerClass.getConstructor().newInstance();
} catch (IllegalArgumentException | ReflectiveOperationException e) {
throw new Asn1DecodingException("Failed to instantiate " + containerClass.getName(), e);
}
// Parse fields one by one. A complication is that there may be optional fields.
int nextUnreadFieldIndex = 0;
BerDataValueReader elementsReader = container.contentsReader();
while (nextUnreadFieldIndex < fields.size()) {
BerDataValue dataValue;
try {
// if this is the first field of an unencoded container then the entire contents of
// the container should be used when assigning to this field.
if (isUnencodedContainer && nextUnreadFieldIndex == 0) {
dataValue = container;
} else {
dataValue = elementsReader.readDataValue();
}
} catch (BerDataValueFormatException e) {
throw new Asn1DecodingException("Malformed data value", e);
}
if (dataValue == null) {
break;
}
for (int i = nextUnreadFieldIndex; i < fields.size(); i++) {
AnnotatedField field = fields.get(i);
try {
if (field.isOptional()) {
// Optional field -- might not be present and we may thus be trying to set
// it from the wrong tag.
try {
field.setValueFrom(dataValue, t);
nextUnreadFieldIndex = i + 1;
break;
} catch (Asn1UnexpectedTagException e) {
// This field is not present, attempt to use this data value for the
// next / iteration of the loop
continue;
}
} else {
// Mandatory field -- if we can't set its value from this data value, then
// it's an error
field.setValueFrom(dataValue, t);
nextUnreadFieldIndex = i + 1;
break;
}
} catch (Asn1DecodingException e) {
throw new Asn1DecodingException(
"Failed to parse " + containerClass.getName()
+ "." + field.getField().getName(),
e);
}
}
}
return t;
}
// NOTE: This method returns List rather than Set because ASN.1 SET_OF does require uniqueness
// of elements -- it's an unordered collection.
@SuppressWarnings("unchecked")
private static <T> List<T> parseSetOf(BerDataValue container, Class<T> elementClass)
throws Asn1DecodingException {
List<T> result = new ArrayList<>();
BerDataValueReader elementsReader = container.contentsReader();
while (true) {
BerDataValue dataValue;
try {
dataValue = elementsReader.readDataValue();
} catch (BerDataValueFormatException e) {
throw new Asn1DecodingException("Malformed data value", e);
}
if (dataValue == null) {
break;
}
T element;
if (ByteBuffer.class.equals(elementClass)) {
element = (T) dataValue.getEncodedContents();
} else if (Asn1OpaqueObject.class.equals(elementClass)) {
element = (T) new Asn1OpaqueObject(dataValue.getEncoded());
} else {
element = parse(dataValue, elementClass);
}
result.add(element);
}
return result;
}
private static Asn1Type getContainerAsn1Type(Class<?> containerClass)
throws Asn1DecodingException {
Asn1Class containerAnnotation = containerClass.getDeclaredAnnotation(Asn1Class.class);
if (containerAnnotation == null) {
throw new Asn1DecodingException(
containerClass.getName() + " is not annotated with "
+ Asn1Class.class.getName());
}
switch (containerAnnotation.type()) {
case CHOICE:
case SEQUENCE:
case UNENCODED_CONTAINER:
return containerAnnotation.type();
default:
throw new Asn1DecodingException(
"Unsupported ASN.1 container annotation type: "
+ containerAnnotation.type());
}
}
private static Class<?> getElementType(Field field)
throws Asn1DecodingException, ClassNotFoundException {
String type = field.getGenericType().getTypeName();
int delimiterIndex = type.indexOf('<');
if (delimiterIndex == -1) {
throw new Asn1DecodingException("Not a container type: " + field.getGenericType());
}
int startIndex = delimiterIndex + 1;
int endIndex = type.indexOf('>', startIndex);
// TODO: handle comma?
if (endIndex == -1) {
throw new Asn1DecodingException("Not a container type: " + field.getGenericType());
}
String elementClassName = type.substring(startIndex, endIndex);
return Class.forName(elementClassName);
}
private static final class AnnotatedField {
private final Field mField;
private final Asn1Field mAnnotation;
private final Asn1Type mDataType;
private final Asn1TagClass mTagClass;
private final int mBerTagClass;
private final int mBerTagNumber;
private final Asn1Tagging mTagging;
private final boolean mOptional;
public AnnotatedField(Field field, Asn1Field annotation) throws Asn1DecodingException {
mField = field;
mAnnotation = annotation;
mDataType = annotation.type();
Asn1TagClass tagClass = annotation.cls();
if (tagClass == Asn1TagClass.AUTOMATIC) {
if (annotation.tagNumber() != -1) {
tagClass = Asn1TagClass.CONTEXT_SPECIFIC;
} else {
tagClass = Asn1TagClass.UNIVERSAL;
}
}
mTagClass = tagClass;
mBerTagClass = BerEncoding.getTagClass(mTagClass);
int tagNumber;
if (annotation.tagNumber() != -1) {
tagNumber = annotation.tagNumber();
} else if ((mDataType == Asn1Type.CHOICE) || (mDataType == Asn1Type.ANY)) {
tagNumber = -1;
} else {
tagNumber = BerEncoding.getTagNumber(mDataType);
}
mBerTagNumber = tagNumber;
mTagging = annotation.tagging();
if (((mTagging == Asn1Tagging.EXPLICIT) || (mTagging == Asn1Tagging.IMPLICIT))
&& (annotation.tagNumber() == -1)) {
throw new Asn1DecodingException(
"Tag number must be specified when tagging mode is " + mTagging);
}
mOptional = annotation.optional();
}
public Field getField() {
return mField;
}
public Asn1Field getAnnotation() {
return mAnnotation;
}
public boolean isOptional() {
return mOptional;
}
public int getBerTagClass() {
return mBerTagClass;
}
public int getBerTagNumber() {
return mBerTagNumber;
}
public void setValueFrom(BerDataValue dataValue, Object obj) throws Asn1DecodingException {
int readTagClass = dataValue.getTagClass();
if (mBerTagNumber != -1) {
int readTagNumber = dataValue.getTagNumber();
if ((readTagClass != mBerTagClass) || (readTagNumber != mBerTagNumber)) {
throw new Asn1UnexpectedTagException(
"Tag mismatch. Expected: "
+ BerEncoding.tagClassAndNumberToString(mBerTagClass, mBerTagNumber)
+ ", but found "
+ BerEncoding.tagClassAndNumberToString(readTagClass, readTagNumber));
}
} else {
if (readTagClass != mBerTagClass) {
throw new Asn1UnexpectedTagException(
"Tag mismatch. Expected class: "
+ BerEncoding.tagClassToString(mBerTagClass)
+ ", but found "
+ BerEncoding.tagClassToString(readTagClass));
}
}
if (mTagging == Asn1Tagging.EXPLICIT) {
try {
dataValue = dataValue.contentsReader().readDataValue();
} catch (BerDataValueFormatException e) {
throw new Asn1DecodingException(
"Failed to read contents of EXPLICIT data value", e);
}
}
BerToJavaConverter.setFieldValue(obj, mField, mDataType, dataValue);
}
}
private static class Asn1UnexpectedTagException extends Asn1DecodingException {
private static final long serialVersionUID = 1L;
public Asn1UnexpectedTagException(String message) {
super(message);
}
}
private static String oidToString(ByteBuffer encodedOid) throws Asn1DecodingException {
if (!encodedOid.hasRemaining()) {
throw new Asn1DecodingException("Empty OBJECT IDENTIFIER");
}
// First component encodes the first two nodes, X.Y, as X * 40 + Y, with 0 <= X <= 2
long firstComponent = decodeBase128UnsignedLong(encodedOid);
int firstNode = (int) Math.min(firstComponent / 40, 2);
long secondNode = firstComponent - firstNode * 40;
StringBuilder result = new StringBuilder();
result.append(Long.toString(firstNode)).append('.')
.append(Long.toString(secondNode));
// Each consecutive node is encoded as a separate component
while (encodedOid.hasRemaining()) {
long node = decodeBase128UnsignedLong(encodedOid);
result.append('.').append(Long.toString(node));
}
return result.toString();
}
private static long decodeBase128UnsignedLong(ByteBuffer encoded) throws Asn1DecodingException {
if (!encoded.hasRemaining()) {
return 0;
}
long result = 0;
while (encoded.hasRemaining()) {
if (result > Long.MAX_VALUE >>> 7) {
throw new Asn1DecodingException("Base-128 number too large");
}
int b = encoded.get() & 0xff;
result <<= 7;
result |= b & 0x7f;
if ((b & 0x80) == 0) {
return result;
}
}
throw new Asn1DecodingException(
"Truncated base-128 encoded input: missing terminating byte, with highest bit not"
+ " set");
}
private static BigInteger integerToBigInteger(ByteBuffer encoded) {
if (!encoded.hasRemaining()) {
return BigInteger.ZERO;
}
return new BigInteger(ByteBufferUtils.toByteArray(encoded));
}
private static int integerToInt(ByteBuffer encoded) throws Asn1DecodingException {
BigInteger value = integerToBigInteger(encoded);
if (value.compareTo(BigInteger.valueOf(Integer.MIN_VALUE)) < 0
|| value.compareTo(BigInteger.valueOf(Integer.MAX_VALUE)) > 0) {
throw new Asn1DecodingException(
String.format("INTEGER cannot be represented as int: %1$d (0x%1$x)", value));
}
return value.intValue();
}
private static long integerToLong(ByteBuffer encoded) throws Asn1DecodingException {
BigInteger value = integerToBigInteger(encoded);
if (value.compareTo(BigInteger.valueOf(Long.MIN_VALUE)) < 0
|| value.compareTo(BigInteger.valueOf(Long.MAX_VALUE)) > 0) {
throw new Asn1DecodingException(
String.format("INTEGER cannot be represented as long: %1$d (0x%1$x)", value));
}
return value.longValue();
}
private static List<AnnotatedField> getAnnotatedFields(Class<?> containerClass)
throws Asn1DecodingException {
Field[] declaredFields = containerClass.getDeclaredFields();
List<AnnotatedField> result = new ArrayList<>(declaredFields.length);
for (Field field : declaredFields) {
Asn1Field annotation = field.getDeclaredAnnotation(Asn1Field.class);
if (annotation == null) {
continue;
}
if (Modifier.isStatic(field.getModifiers())) {
throw new Asn1DecodingException(
Asn1Field.class.getName() + " used on a static field: "
+ containerClass.getName() + "." + field.getName());
}
AnnotatedField annotatedField;
try {
annotatedField = new AnnotatedField(field, annotation);
} catch (Asn1DecodingException e) {
throw new Asn1DecodingException(
"Invalid ASN.1 annotation on "
+ containerClass.getName() + "." + field.getName(),
e);
}
result.add(annotatedField);
}
return result;
}
private static final class BerToJavaConverter {
private BerToJavaConverter() {}
public static void setFieldValue(
Object obj, Field field, Asn1Type type, BerDataValue dataValue)
throws Asn1DecodingException {
try {
switch (type) {
case SET_OF:
case SEQUENCE_OF:
if (Asn1OpaqueObject.class.equals(field.getType())) {
field.set(obj, convert(type, dataValue, field.getType()));
} else {
field.set(obj, parseSetOf(dataValue, getElementType(field)));
}
return;
default:
field.set(obj, convert(type, dataValue, field.getType()));
break;
}
} catch (ReflectiveOperationException e) {
throw new Asn1DecodingException(
"Failed to set value of " + obj.getClass().getName()
+ "." + field.getName(),
e);
}
}
private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
@SuppressWarnings("unchecked")
public static <T> T convert(
Asn1Type sourceType,
BerDataValue dataValue,
Class<T> targetType) throws Asn1DecodingException {
if (ByteBuffer.class.equals(targetType)) {
return (T) dataValue.getEncodedContents();
} else if (byte[].class.equals(targetType)) {
ByteBuffer resultBuf = dataValue.getEncodedContents();
if (!resultBuf.hasRemaining()) {
return (T) EMPTY_BYTE_ARRAY;
}
byte[] result = new byte[resultBuf.remaining()];
resultBuf.get(result);
return (T) result;
} else if (Asn1OpaqueObject.class.equals(targetType)) {
return (T) new Asn1OpaqueObject(dataValue.getEncoded());
}
ByteBuffer encodedContents = dataValue.getEncodedContents();
switch (sourceType) {
case INTEGER:
if ((int.class.equals(targetType)) || (Integer.class.equals(targetType))) {
return (T) Integer.valueOf(integerToInt(encodedContents));
} else if ((long.class.equals(targetType)) || (Long.class.equals(targetType))) {
return (T) Long.valueOf(integerToLong(encodedContents));
} else if (BigInteger.class.equals(targetType)) {
return (T) integerToBigInteger(encodedContents);
}
break;
case OBJECT_IDENTIFIER:
if (String.class.equals(targetType)) {
return (T) oidToString(encodedContents);
}
break;
case UTC_TIME:
case GENERALIZED_TIME:
if (String.class.equals(targetType)) {
return (T) new String(ByteBufferUtils.toByteArray(encodedContents));
}
break;
case BOOLEAN:
// A boolean should be encoded in a single byte with a value of 0 for false and
// any non-zero value for true.
if (boolean.class.equals(targetType)) {
if (encodedContents.remaining() != 1) {
throw new Asn1DecodingException(
"Incorrect encoded size of boolean value: "
+ encodedContents.remaining());
}
boolean result;
if (encodedContents.get() == 0) {
result = false;
} else {
result = true;
}
return (T) new Boolean(result);
}
break;
case SEQUENCE:
{
Asn1Class containerAnnotation =
targetType.getDeclaredAnnotation(Asn1Class.class);
if ((containerAnnotation != null)
&& (containerAnnotation.type() == Asn1Type.SEQUENCE)) {
return parseSequence(dataValue, targetType);
}
break;
}
case CHOICE:
{
Asn1Class containerAnnotation =
targetType.getDeclaredAnnotation(Asn1Class.class);
if ((containerAnnotation != null)
&& (containerAnnotation.type() == Asn1Type.CHOICE)) {
return parseChoice(dataValue, targetType);
}
break;
}
default:
break;
}
throw new Asn1DecodingException(
"Unsupported conversion: ASN.1 " + sourceType + " to " + targetType.getName());
}
}
}
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