96 lines
3.1 KiB
Java
96 lines
3.1 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.tomcat.util.buf;
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public class Asn1Writer {
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public static byte[] writeSequence(byte[]... components) {
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int len = 0;
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for (byte[] component : components) {
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len += component.length;
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}
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byte[] combined = new byte[len];
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int pos = 0;
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for (byte[] component : components) {
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System.arraycopy(component, 0, combined, pos, component.length);
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pos += component.length;
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}
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return writeTag((byte) 0x30, combined);
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}
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public static byte[] writeInteger(int value) {
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// How many bytes required to write the value? No more than 4 for int.
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int valueSize = 1;
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while ((value >> (valueSize * 8)) > 0) {
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valueSize++;
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}
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byte[] valueBytes = new byte[valueSize];
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int i = 0;
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while (valueSize > 0) {
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valueBytes[i] = (byte) (value >> (8 * (valueSize - 1)));
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value = value >> 8;
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valueSize--;
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i++;
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}
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return writeTag((byte) 0x02, valueBytes);
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}
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public static byte[] writeOctetString(byte[] data) {
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return writeTag((byte) 0x04, data);
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}
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public static byte[] writeTag(byte tagId, byte[] data) {
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int dataSize = data.length;
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// How many bytes to write the length?
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int lengthSize = 1;
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if (dataSize >127) {
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// 1 byte we have is now used to record how many bytes we need to
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// record a length > 127
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// Result is lengthSize = 1 + number of bytes to record length
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do {
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lengthSize++;
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}
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while ((dataSize >> (lengthSize * 8)) > 0);
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}
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// 1 for tag + lengthSize + dataSize
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byte[] result = new byte[1 + lengthSize + dataSize];
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result[0] = tagId;
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if (dataSize < 128) {
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result[1] = (byte) dataSize;
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} else {
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// lengthSize is 1 + number of bytes for length
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result[1] = (byte) (127 + lengthSize);
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int i = lengthSize;
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while (dataSize > 0) {
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result[i] = (byte) (dataSize & 0xFF);
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dataSize = dataSize >> 8;
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i--;
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}
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}
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System.arraycopy(data, 0, result, 1 + lengthSize, data.length);
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return result;
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}
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}
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