001/*
002 * Copyright (c) 2011-2017 Nexmo Inc
003 *
004 * Permission is hereby granted, free of charge, to any person obtaining a copy
005 * of this software and associated documentation files (the "Software"), to deal
006 * in the Software without restriction, including without limitation the rights
007 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
008 * copies of the Software, and to permit persons to whom the Software is
009 * furnished to do so, subject to the following conditions:
010 *
011 * The above copyright notice and this permission notice shall be included in
012 * all copies or substantial portions of the Software.
013 *
014 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
015 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
016 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
017 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
018 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
019 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
020 * THE SOFTWARE.
021 */
022package com.nexmo.client.sms;
023
024import com.nexmo.client.NexmoUnexpectedException;
025
026import java.io.UnsupportedEncodingException;
027
028
029/**
030 * Static helper methods for working with hex values.
031 *
032 * @author Paul Cook
033 */
034public class HexUtil {
035
036    private static final char[] HEX_CHARS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', };
037
038    private HexUtil() {
039        // This class may not be instantiated.
040    }
041
042    /**
043     * translate a byte array of raw data into a String with a hex representation of that data
044     *
045     * @param bytes raw binary data
046     *
047     * @return String Hex representation of the raw data
048     */
049    public static String bytesToHex(byte[] bytes) {
050        return bytesToHex(bytes, null);
051    }
052
053    /**
054     * translate a byte array of raw data into a String with a hex representation of that data.
055     * Each octet will be separated with a specific separator.
056     *
057     * @param bytes raw binary data
058     * @param separator This string will be injected into the output in between each octet in the stream
059     *
060     * @return String Hex representation of the raw data with each octet separated by 'separator'
061     */
062    public static String bytesToHex(byte[] bytes, String separator) {
063        StringBuilder tmpBuffer = new StringBuilder();
064        if (bytes != null) {
065            for (byte c : bytes) {
066                int b = c;
067                if (b < 0)
068                    b += 256;
069                if (separator != null)
070                    tmpBuffer.append(separator);
071                tmpBuffer.append(HEX_CHARS[(b & 0xf0) / 0x10]); // note, this benchmarks faster than using >> 4
072                tmpBuffer.append(HEX_CHARS[b & 0x0f]);
073            }
074        }
075        return tmpBuffer.toString();
076    }
077
078    /**
079     * Converts a Hex encoded String into a byte vector.
080     *
081     * @param str The String to be encoded.
082     *
083     * @return A byte vector representing the String.
084     */
085    public static byte[] hexToBytes(String str) {
086        if (str == null)
087            return null;
088        byte[] hexChars;
089        try {
090            hexChars = str.toUpperCase().getBytes("ISO_8859-1");
091        } catch (UnsupportedEncodingException e) {
092            throw new NexmoUnexpectedException("ISO_8859_1 is an unsupported encoding in this JVM");
093        }
094        int size = hexChars.length;
095        byte[] bytes = new byte[size / 2];
096        int first;
097        int second;
098
099        int rIndex = 0;
100        // Convert to bytes.
101        for (int i = 0; i+1 <size; i= i + 2) {
102
103            // Convert first
104            first = hexChars[i];
105            if (first < 58)
106                first = ((first - 48) * 16); // 0 - 9
107            else
108                first = ((first - 55) * 16); // A - F
109
110            // Convert second
111            second = hexChars[i + 1];
112            if (second < 58)
113                second = second - 48; // 0 - 9
114            else
115                second = second - 55; // A - F
116
117            //Value must be between -128 and 127
118            int total = (first + second);
119            if (total > 127)
120                total = (256 + total);
121
122            bytes[rIndex] = (byte) total;
123            rIndex++;
124        }
125        return bytes;
126    }
127
128}