1// Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org)
2
3package org.xbill.DNS.utils;
4
5import java.io.*;
6
7/**
8 * Routines for converting between Strings of base64-encoded data and arrays of
9 * binary data.
10 *
11 * @author Brian Wellington
12 */
13
14public class base64 {
15
16private static final String Base64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
17
18private
19base64() {}
20
21/**
22 * Convert binary data to a base64-encoded String
23 * @param b An array containing binary data
24 * @return A String containing the encoded data
25 */
26public static String
27toString(byte [] b) {
28	ByteArrayOutputStream os = new ByteArrayOutputStream();
29
30	for (int i = 0; i < (b.length + 2) / 3; i++) {
31		short [] s = new short[3];
32		short [] t = new short[4];
33		for (int j = 0; j < 3; j++) {
34			if ((i * 3 + j) < b.length)
35				s[j] = (short) (b[i*3+j] & 0xFF);
36			else
37				s[j] = -1;
38		}
39
40		t[0] = (short) (s[0] >> 2);
41		if (s[1] == -1)
42			t[1] = (short) (((s[0] & 0x3) << 4));
43		else
44			t[1] = (short) (((s[0] & 0x3) << 4) + (s[1] >> 4));
45		if (s[1] == -1)
46			t[2] = t[3] = 64;
47		else if (s[2] == -1) {
48			t[2] = (short) (((s[1] & 0xF) << 2));
49			t[3] = 64;
50		}
51		else {
52			t[2] = (short) (((s[1] & 0xF) << 2) + (s[2] >> 6));
53			t[3] = (short) (s[2] & 0x3F);
54		}
55		for (int j = 0; j < 4; j++)
56			os.write(Base64.charAt(t[j]));
57	}
58	return new String(os.toByteArray());
59}
60
61/**
62 * Formats data into a nicely formatted base64 encoded String
63 * @param b An array containing binary data
64 * @param lineLength The number of characters per line
65 * @param prefix A string prefixing the characters on each line
66 * @param addClose Whether to add a close parenthesis or not
67 * @return A String representing the formatted output
68 */
69public static String
70formatString(byte [] b, int lineLength, String prefix, boolean addClose) {
71	String s = toString(b);
72	StringBuffer sb = new StringBuffer();
73	for (int i = 0; i < s.length(); i += lineLength) {
74		sb.append (prefix);
75		if (i + lineLength >= s.length()) {
76			sb.append(s.substring(i));
77			if (addClose)
78				sb.append(" )");
79		}
80		else {
81			sb.append(s.substring(i, i + lineLength));
82			sb.append("\n");
83		}
84	}
85	return sb.toString();
86}
87
88
89/**
90 * Convert a base64-encoded String to binary data
91 * @param str A String containing the encoded data
92 * @return An array containing the binary data, or null if the string is invalid
93 */
94public static byte []
95fromString(String str) {
96	ByteArrayOutputStream bs = new ByteArrayOutputStream();
97	byte [] raw = str.getBytes();
98	for (int i = 0; i < raw.length; i++) {
99		if (!Character.isWhitespace((char)raw[i]))
100			bs.write(raw[i]);
101	}
102	byte [] in = bs.toByteArray();
103	if (in.length % 4 != 0) {
104		return null;
105	}
106
107	bs.reset();
108	DataOutputStream ds = new DataOutputStream(bs);
109
110	for (int i = 0; i < (in.length + 3) / 4; i++) {
111		short [] s = new short[4];
112		short [] t = new short[3];
113
114		for (int j = 0; j < 4; j++)
115			s[j] = (short) Base64.indexOf(in[i*4+j]);
116
117		t[0] = (short) ((s[0] << 2) + (s[1] >> 4));
118		if (s[2] == 64) {
119			t[1] = t[2] = (short) (-1);
120			if ((s[1] & 0xF) != 0)
121				return null;
122		}
123		else if (s[3] == 64) {
124			t[1] = (short) (((s[1] << 4) + (s[2] >> 2)) & 0xFF);
125			t[2] = (short) (-1);
126			if ((s[2] & 0x3) != 0)
127				return null;
128		}
129		else {
130			t[1] = (short) (((s[1] << 4) + (s[2] >> 2)) & 0xFF);
131			t[2] = (short) (((s[2] << 6) + s[3]) & 0xFF);
132		}
133
134		try {
135			for (int j = 0; j < 3; j++)
136				if (t[j] >= 0)
137					ds.writeByte(t[j]);
138		}
139		catch (IOException e) {
140		}
141	}
142	return bs.toByteArray();
143}
144
145}
146