init

java/org/apache/tomcat/util/buf/Asn1Parser.java

@@ -0,0 +1,95 @@
+/*
+ * 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.
+ */
+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;
+    }
+}