/*
 * 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.tomcat.util.buf;

import java.math.BigInteger;

import org.apache.tomcat.util.res.StringManager;

This is a very basic ASN.1 parser that provides the limited functionality required by Tomcat. It is a long way from a complete parser. TODO: Consider extending this parser and refactoring the SpnegoTokenFixer to use it.
/** * This is a very basic ASN.1 parser that provides the limited functionality * required by Tomcat. It is a long way from a complete parser. * * TODO: Consider extending this parser and refactoring the SpnegoTokenFixer to * use it. */
public class Asn1Parser { private static final StringManager sm = StringManager.getManager(Asn1Parser.class); private final byte[] source; private int pos = 0; public Asn1Parser(byte[] source) { this.source = source; } public void parseTag(int tag) { int value = next(); if (value != tag) { throw new IllegalArgumentException(sm.getString("asn1Parser.tagMismatch", Integer.valueOf(tag), Integer.valueOf(value))); } } public void parseFullLength() { int len = parseLength(); if (len + pos != source.length) { throw new IllegalArgumentException(sm.getString("asn1Parser.lengthInvalid", Integer.valueOf(len), Integer.valueOf(source.length - pos))); } } public int parseLength() { int len = next(); if (len > 127) { int bytes = len - 128; len = 0; for (int i = 0; i < bytes; i++) { len = len << 8; len = len + next(); } } return len; } public BigInteger parseInt() { parseTag(0x02); int len = parseLength(); byte[] val = new byte[len]; System.arraycopy(source, pos, val, 0, len); pos += len; return new BigInteger(val); } public void parseBytes(byte[] dest) { System.arraycopy(source, pos, dest, 0, dest.length); pos += dest.length; } private int next() { return source[pos++] & 0xFF; } }