| /** |
| * 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.io.IOException; |
| 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 Tag readTag(ByteBuffer buffer) throws IOException { |
| int tagFlags = readTagFlags(buffer); |
| int tagNo = readTagNo(buffer, tagFlags); |
| return new Tag(tagFlags, tagNo); |
| } |
| |
| private static int readTagFlags(ByteBuffer buffer) throws IOException { |
| int tagFlags = buffer.get() & 0xff; |
| if (tagFlags == 0) { |
| throw new IOException("Bad tag 0 found"); |
| } |
| return tagFlags; |
| } |
| |
| private static int readTagNo(ByteBuffer buffer, int tagFlags) throws IOException { |
| int tagNo = tagFlags & 0x1f; |
| |
| if (tagNo == 0x1f) { |
| tagNo = 0; |
| |
| int b = buffer.get() & 0xff; |
| if ((b & 0x7f) == 0) { |
| throw new IOException("Invalid high tag number found"); |
| } |
| |
| while (b >= 0 && (b & 0x80) != 0) { |
| tagNo |= b & 0x7f; |
| tagNo <<= 7; |
| b = buffer.get(); |
| } |
| |
| tagNo |= b & 0x7f; |
| } |
| |
| return tagNo; |
| } |
| |
| public static int readLength(ByteBuffer buffer) throws IOException { |
| int result = buffer.get() & 0xff; |
| if (result == 0x80) { |
| return -1; // non-definitive length |
| } |
| |
| if (result > 127) { |
| int length = result & 0x7f; |
| if (length > 4) { |
| throw new IOException("Bad length of more than 4 bytes: " + length); |
| } |
| |
| result = 0; |
| int tmp; |
| for (int i = 0; i < length; i++) { |
| tmp = buffer.get() & 0xff; |
| result = (result << 8) + tmp; |
| } |
| } |
| |
| if (result < 0) { |
| throw new IOException("Invalid length " + result); |
| } |
| |
| if (result > buffer.remaining()) { |
| throw new IOException("Corrupt stream - less data " |
| + buffer.remaining() + " than expected " + result); |
| } |
| |
| return result; |
| } |
| |
| public static ByteBuffer dupWithLength(ByteBuffer buffer, int length) { |
| try { |
| ByteBuffer result = buffer.duplicate(); |
| result.limit(buffer.position() + length); |
| buffer.position(buffer.position() + length); |
| return result; |
| } catch (Exception e) { |
| throw e; |
| } |
| } |
| |
| public static byte[] readAllLeftBytes(ByteBuffer buffer) { |
| byte[] result = new byte[buffer.remaining()]; |
| buffer.get(result); |
| return result; |
| } |
| } |