1 // Copyright (c) 1999-2004 Brian Wellington (bwelling (at) 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 } 74
