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java/org/apache/tomcat/util/http/HeaderUtil.java

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+/*
+ *  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.http;
+
+public class HeaderUtil {
+
+    /**
+     * Converts an HTTP header line in byte form to a printable String.
+     * Bytes corresponding to visible ASCII characters will converted to those
+     * characters. All other bytes (0x00 to 0x1F, 0x7F to OxFF) will be
+     * represented in 0xNN form.
+     *
+     * @param bytes  Contains an HTTP header line
+     * @param offset The start position of the header line in the array
+     * @param len    The length of the HTTP header line
+     *
+     * @return A String with non-printing characters replaced by the 0xNN
+     *         equivalent
+     */
+    public static String toPrintableString(byte[] bytes, int offset, int len) {
+        StringBuilder result = new StringBuilder();
+        for (int i = offset; i < offset + len; i++) {
+            char c = (char) (bytes[i] & 0xFF);
+            if (c < 0x20 || c > 0x7E) {
+                result.append("0x");
+                result.append(Character.forDigit((c >> 4) & 0xF, 16));
+                result.append(Character.forDigit((c) & 0xF, 16));
+            } else {
+                result.append(c);
+            }
+        }
+        return result.toString();
+    }
+
+
+    private HeaderUtil() {
+        // Utility class. Hide default constructor.
+    }
+}