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// Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org)
package org.xbill.DNS.utils;
import java.io.*;
/**
* Routines for converting between Strings of base64-encoded data and arrays of
* binary data.
*
* @author Brian Wellington
*/
public class base64 {
private static final String Base64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
private
base64() {}
/**
* Convert binary data to a base64-encoded String
* @param b An array containing binary data
* @return A String containing the encoded data
*/
public static String
toString(byte [] b) {
ByteArrayOutputStream os = new ByteArrayOutputStream();
for (int i = 0; i < (b.length + 2) / 3; i++) {
short [] s = new short[3];
short [] t = new short[4];
for (int j = 0; j < 3; j++) {
if ((i * 3 + j) < b.length)
s[j] = (short) (b[i*3+j] & 0xFF);
else
s[j] = -1;
}
t[0] = (short) (s[0] >> 2);
if (s[1] == -1)
t[1] = (short) (((s[0] & 0x3) << 4));
else
t[1] = (short) (((s[0] & 0x3) << 4) + (s[1] >> 4));
if (s[1] == -1)
t[2] = t[3] = 64;
else if (s[2] == -1) {
t[2] = (short) (((s[1] & 0xF) << 2));
t[3] = 64;
}
else {
t[2] = (short) (((s[1] & 0xF) << 2) + (s[2] >> 6));
t[3] = (short) (s[2] & 0x3F);
}
for (int j = 0; j < 4; j++)
os.write(Base64.charAt(t[j]));
}
return new String(os.toByteArray());
}
/**
* Formats data into a nicely formatted base64 encoded String
* @param b An array containing binary data
* @param lineLength The number of characters per line
* @param prefix A string prefixing the characters on each line
* @param addClose Whether to add a close parenthesis or not
* @return A String representing the formatted output
*/
public static String
formatString(byte [] b, int lineLength, String prefix, boolean addClose) {
String s = toString(b);
StringBuffer sb = new StringBuffer();
for (int i = 0; i < s.length(); i += lineLength) {
sb.append (prefix);
if (i + lineLength >= s.length()) {
sb.append(s.substring(i));
if (addClose)
sb.append(" )");
}
else {
sb.append(s.substring(i, i + lineLength));
sb.append("\n");
}
}
return sb.toString();
}
/**
* Convert a base64-encoded String to binary data
* @param str A String containing the encoded data
* @return An array containing the binary data, or null if the string is invalid
*/
public static byte []
fromString(String str) {
ByteArrayOutputStream bs = new ByteArrayOutputStream();
byte [] raw = str.getBytes();
for (int i = 0; i < raw.length; i++) {
if (!Character.isWhitespace((char)raw[i]))
bs.write(raw[i]);
}
byte [] in = bs.toByteArray();
if (in.length % 4 != 0) {
return null;
}
bs.reset();
DataOutputStream ds = new DataOutputStream(bs);
for (int i = 0; i < (in.length + 3) / 4; i++) {
short [] s = new short[4];
short [] t = new short[3];
for (int j = 0; j < 4; j++)
s[j] = (short) Base64.indexOf(in[i*4+j]);
t[0] = (short) ((s[0] << 2) + (s[1] >> 4));
if (s[2] == 64) {
t[1] = t[2] = (short) (-1);
if ((s[1] & 0xF) != 0)
return null;
}
else if (s[3] == 64) {
t[1] = (short) (((s[1] << 4) + (s[2] >> 2)) & 0xFF);
t[2] = (short) (-1);
if ((s[2] & 0x3) != 0)
return null;
}
else {
t[1] = (short) (((s[1] << 4) + (s[2] >> 2)) & 0xFF);
t[2] = (short) (((s[2] << 6) + s[3]) & 0xFF);
}
try {
for (int j = 0; j < 3; j++)
if (t[j] >= 0)
ds.writeByte(t[j]);
}
catch (IOException e) {
}
}
return bs.toByteArray();
}
}
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