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java/org/apache/tomcat/util/buf/HexUtils.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.buf;
+
+import org.apache.tomcat.util.res.StringManager;
+
+/**
+ * Tables useful when converting byte arrays to and from strings of hexadecimal
+ * digits.
+ * Code from Ajp11, from Apache's JServ.
+ *
+ * @author Craig R. McClanahan
+ */
+public final class HexUtils {
+
+    private static final StringManager sm =
+            StringManager.getManager(Constants.Package);
+
+    // -------------------------------------------------------------- Constants
+
+    /**
+     *  Table for HEX to DEC byte translation.
+     */
+    private static final int[] DEC = {
+        00, 01, 02, 03, 04, 05, 06, 07,  8,  9, -1, -1, -1, -1, -1, -1,
+        -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, 10, 11, 12, 13, 14, 15,
+    };
+
+
+    /**
+     * Table for DEC to HEX byte translation.
+     */
+    private static final byte[] HEX =
+    { (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5',
+      (byte) '6', (byte) '7', (byte) '8', (byte) '9', (byte) 'a', (byte) 'b',
+      (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f' };
+
+
+    /**
+     * Table for byte to hex string translation.
+     */
+    private static final char[] hex = "0123456789abcdef".toCharArray();
+
+
+    // --------------------------------------------------------- Static Methods
+
+    public static int getDec(int index) {
+        // Fast for correct values, slower for incorrect ones
+        try {
+            return DEC[index - '0'];
+        } catch (ArrayIndexOutOfBoundsException ex) {
+            return -1;
+        }
+    }
+
+
+    public static byte getHex(int index) {
+        return HEX[index];
+    }
+
+
+    public static String toHexString(byte[] bytes) {
+        if (null == bytes) {
+            return null;
+        }
+
+        StringBuilder sb = new StringBuilder(bytes.length << 1);
+
+        for(int i = 0; i < bytes.length; ++i) {
+            sb.append(hex[(bytes[i] & 0xf0) >> 4])
+                .append(hex[(bytes[i] & 0x0f)])
+                ;
+        }
+
+        return sb.toString();
+    }
+
+
+    public static byte[] fromHexString(String input) {
+        if (input == null) {
+            return null;
+        }
+
+        if ((input.length() & 1) == 1) {
+            // Odd number of characters
+            throw new IllegalArgumentException(sm.getString("hexUtils.fromHex.oddDigits"));
+        }
+
+        char[] inputChars = input.toCharArray();
+        byte[] result = new byte[input.length() >> 1];
+        for (int i = 0; i < result.length; i++) {
+            int upperNibble = getDec(inputChars[2*i]);
+            int lowerNibble =  getDec(inputChars[2*i + 1]);
+            if (upperNibble < 0 || lowerNibble < 0) {
+                // Non hex character
+                throw new IllegalArgumentException(sm.getString("hexUtils.fromHex.nonHex"));
+            }
+            result[i] = (byte) ((upperNibble << 4) + lowerNibble);
+        }
+        return result;
+    }
+}