Shuyi Chen | d7955ce | 2013-05-22 14:51:55 -0700 | [diff] [blame] | 1 | // Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org) |
| 2 | |
| 3 | package org.xbill.DNS.utils; |
| 4 | |
| 5 | import java.io.*; |
| 6 | |
| 7 | /** |
| 8 | * Routines for converting between Strings of hex-encoded data and arrays of |
| 9 | * binary data. This is not actually used by DNS. |
| 10 | * |
| 11 | * @author Brian Wellington |
| 12 | */ |
| 13 | |
| 14 | public class base16 { |
| 15 | |
| 16 | private static final String Base16 = "0123456789ABCDEF"; |
| 17 | |
| 18 | private |
| 19 | base16() {} |
| 20 | |
| 21 | /** |
| 22 | * Convert binary data to a hex-encoded String |
| 23 | * @param b An array containing binary data |
| 24 | * @return A String containing the encoded data |
| 25 | */ |
| 26 | public static String |
| 27 | toString(byte [] b) { |
| 28 | ByteArrayOutputStream os = new ByteArrayOutputStream(); |
| 29 | |
| 30 | for (int i = 0; i < b.length; i++) { |
| 31 | short value = (short) (b[i] & 0xFF); |
| 32 | byte high = (byte) (value >> 4); |
| 33 | byte low = (byte) (value & 0xF); |
| 34 | os.write(Base16.charAt(high)); |
| 35 | os.write(Base16.charAt(low)); |
| 36 | } |
| 37 | return new String(os.toByteArray()); |
| 38 | } |
| 39 | |
| 40 | /** |
| 41 | * Convert a hex-encoded String to binary data |
| 42 | * @param str A String containing the encoded data |
| 43 | * @return An array containing the binary data, or null if the string is invalid |
| 44 | */ |
| 45 | public static byte [] |
| 46 | fromString(String str) { |
| 47 | ByteArrayOutputStream bs = new ByteArrayOutputStream(); |
| 48 | byte [] raw = str.getBytes(); |
| 49 | for (int i = 0; i < raw.length; i++) { |
| 50 | if (!Character.isWhitespace((char)raw[i])) |
| 51 | bs.write(raw[i]); |
| 52 | } |
| 53 | byte [] in = bs.toByteArray(); |
| 54 | if (in.length % 2 != 0) { |
| 55 | return null; |
| 56 | } |
| 57 | |
| 58 | bs.reset(); |
| 59 | DataOutputStream ds = new DataOutputStream(bs); |
| 60 | |
| 61 | for (int i = 0; i < in.length; i += 2) { |
| 62 | byte high = (byte) Base16.indexOf(Character.toUpperCase((char)in[i])); |
| 63 | byte low = (byte) Base16.indexOf(Character.toUpperCase((char)in[i+1])); |
| 64 | try { |
| 65 | ds.writeByte((high << 4) + low); |
| 66 | } |
| 67 | catch (IOException e) { |
| 68 | } |
| 69 | } |
| 70 | return bs.toByteArray(); |
| 71 | } |
| 72 | |
| 73 | } |