| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 org.apache.kerby.asn1; |
| |
| import java.nio.ByteBuffer; |
| |
| /** |
| * The abstract ASN1 object for all the ASN1 types. It provides basic |
| * encoding and decoding utilities. |
| */ |
| public final class Asn1Util { |
| private Asn1Util() { |
| |
| } |
| |
| public static int lengthOfBodyLength(int bodyLength) { |
| int length = 1; |
| |
| if (bodyLength > 127) { |
| int payload = bodyLength; |
| while (payload != 0) { |
| payload >>= 8; |
| length++; |
| } |
| } |
| |
| return length; |
| } |
| |
| public static int lengthOfTagLength(int tagNo) { |
| int length = 1; |
| |
| if (tagNo >= 31) { |
| if (tagNo < 128) { |
| length++; |
| } else { |
| length++; |
| |
| do { |
| tagNo >>= 7; |
| length++; |
| } while (tagNo > 127); |
| } |
| } |
| |
| return length; |
| } |
| |
| public static void encodeTag(ByteBuffer buffer, Tag tag) { |
| int flags = tag.tagFlags(); |
| int tagNo = tag.tagNo(); |
| |
| if (tagNo < 31) { |
| buffer.put((byte) (flags | tagNo)); |
| } else { |
| buffer.put((byte) (flags | 0x1f)); |
| if (tagNo < 128) { |
| buffer.put((byte) tagNo); |
| } else { |
| byte[] tmpBytes = new byte[5]; // 5 * 7 > 32 |
| int iPut = tmpBytes.length; |
| |
| tmpBytes[--iPut] = (byte) (tagNo & 0x7f); |
| do { |
| tagNo >>= 7; |
| tmpBytes[--iPut] = (byte) (tagNo & 0x7f | 0x80); |
| } while (tagNo > 127); |
| |
| buffer.put(tmpBytes, iPut, tmpBytes.length - iPut); |
| } |
| } |
| } |
| |
| public static void encodeLength(ByteBuffer buffer, int bodyLength) { |
| if (bodyLength < 128) { |
| buffer.put((byte) bodyLength); |
| } else { |
| int length = 0; |
| int payload = bodyLength; |
| |
| while (payload != 0) { |
| payload >>= 8; |
| length++; |
| } |
| |
| buffer.put((byte) (length | 0x80)); |
| |
| payload = bodyLength; |
| for (int i = length - 1; i >= 0; i--) { |
| buffer.put((byte) (payload >> (i * 8))); |
| } |
| } |
| } |
| |
| public static byte[] readAllLeftBytes(ByteBuffer buffer) { |
| byte[] result = new byte[buffer.remaining()]; |
| buffer.get(result); |
| return result; |
| } |
| } |