org.apache.geronimo.mail.util.Base64Encoder Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.geronimo.mail.util;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
public class Base64Encoder
implements Encoder
{
protected final byte[] encodingTable =
{
(byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F', (byte)'G',
(byte)'H', (byte)'I', (byte)'J', (byte)'K', (byte)'L', (byte)'M', (byte)'N',
(byte)'O', (byte)'P', (byte)'Q', (byte)'R', (byte)'S', (byte)'T', (byte)'U',
(byte)'V', (byte)'W', (byte)'X', (byte)'Y', (byte)'Z',
(byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f', (byte)'g',
(byte)'h', (byte)'i', (byte)'j', (byte)'k', (byte)'l', (byte)'m', (byte)'n',
(byte)'o', (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t', (byte)'u',
(byte)'v',
(byte)'w', (byte)'x', (byte)'y', (byte)'z',
(byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5', (byte)'6',
(byte)'7', (byte)'8', (byte)'9',
(byte)'+', (byte)'/'
};
protected byte padding = (byte)'=';
/*
* set up the decoding table.
*/
protected final byte[] decodingTable = new byte[256];
protected void initialiseDecodingTable()
{
for (int i = 0; i < encodingTable.length; i++)
{
decodingTable[encodingTable[i]] = (byte)i;
}
}
public Base64Encoder()
{
initialiseDecodingTable();
}
/**
* encode the input data producing a base 64 output stream.
*
* @return the number of bytes produced.
*/
public int encode(
byte[] data,
int off,
int length,
OutputStream out)
throws IOException
{
int modulus = length % 3;
int dataLength = (length - modulus);
int a1, a2, a3;
for (int i = off; i < off + dataLength; i += 3)
{
a1 = data[i] & 0xff;
a2 = data[i + 1] & 0xff;
a3 = data[i + 2] & 0xff;
out.write(encodingTable[(a1 >>> 2) & 0x3f]);
out.write(encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3f]);
out.write(encodingTable[((a2 << 2) | (a3 >>> 6)) & 0x3f]);
out.write(encodingTable[a3 & 0x3f]);
}
/*
* process the tail end.
*/
int b1, b2, b3;
int d1, d2;
switch (modulus)
{
case 0: /* nothing left to do */
break;
case 1:
d1 = data[off + dataLength] & 0xff;
b1 = (d1 >>> 2) & 0x3f;
b2 = (d1 << 4) & 0x3f;
out.write(encodingTable[b1]);
out.write(encodingTable[b2]);
out.write(padding);
out.write(padding);
break;
case 2:
d1 = data[off + dataLength] & 0xff;
d2 = data[off + dataLength + 1] & 0xff;
b1 = (d1 >>> 2) & 0x3f;
b2 = ((d1 << 4) | (d2 >>> 4)) & 0x3f;
b3 = (d2 << 2) & 0x3f;
out.write(encodingTable[b1]);
out.write(encodingTable[b2]);
out.write(encodingTable[b3]);
out.write(padding);
break;
}
return (dataLength / 3) * 4 + ((modulus == 0) ? 0 : 4);
}
private boolean ignore(
char c)
{
return (c == '\n' || c =='\r' || c == '\t' || c == ' ');
}
/**
* decode the base 64 encoded byte data writing it to the given output stream,
* whitespace characters will be ignored.
*
* @return the number of bytes produced.
*/
public int decode(
byte[] data,
int off,
int length,
OutputStream out)
throws IOException
{
byte[] bytes;
byte b1, b2, b3, b4;
int outLen = 0;
int end = off + length;
while (end > 0)
{
if (!ignore((char)data[end - 1]))
{
break;
}
end--;
}
int i = off;
int finish = end - 4;
while (i < finish)
{
while ((i < finish) && ignore((char)data[i]))
{
i++;
}
b1 = decodingTable[data[i++]];
while ((i < finish) && ignore((char)data[i]))
{
i++;
}
b2 = decodingTable[data[i++]];
while ((i < finish) && ignore((char)data[i]))
{
i++;
}
b3 = decodingTable[data[i++]];
while ((i < finish) && ignore((char)data[i]))
{
i++;
}
b4 = decodingTable[data[i++]];
out.write((b1 << 2) | (b2 >> 4));
out.write((b2 << 4) | (b3 >> 2));
out.write((b3 << 6) | b4);
outLen += 3;
}
if (data[end - 2] == padding)
{
b1 = decodingTable[data[end - 4]];
b2 = decodingTable[data[end - 3]];
out.write((b1 << 2) | (b2 >> 4));
outLen += 1;
}
else if (data[end - 1] == padding)
{
b1 = decodingTable[data[end - 4]];
b2 = decodingTable[data[end - 3]];
b3 = decodingTable[data[end - 2]];
out.write((b1 << 2) | (b2 >> 4));
out.write((b2 << 4) | (b3 >> 2));
outLen += 2;
}
else
{
b1 = decodingTable[data[end - 4]];
b2 = decodingTable[data[end - 3]];
b3 = decodingTable[data[end - 2]];
b4 = decodingTable[data[end - 1]];
out.write((b1 << 2) | (b2 >> 4));
out.write((b2 << 4) | (b3 >> 2));
out.write((b3 << 6) | b4);
outLen += 3;
}
return outLen;
}
/**
* decode the base 64 encoded String data writing it to the given output stream,
* whitespace characters will be ignored.
*
* @return the number of bytes produced.
*/
public int decode(
String data,
OutputStream out)
throws IOException
{
byte[] bytes;
byte b1, b2, b3, b4;
int length = 0;
int end = data.length();
while (end > 0)
{
if (!ignore(data.charAt(end - 1)))
{
break;
}
end--;
}
int i = 0;
int finish = end - 4;
while (i < finish)
{
while ((i < finish) && ignore(data.charAt(i)))
{
i++;
}
b1 = decodingTable[data.charAt(i++)];
while ((i < finish) && ignore(data.charAt(i)))
{
i++;
}
b2 = decodingTable[data.charAt(i++)];
while ((i < finish) && ignore(data.charAt(i)))
{
i++;
}
b3 = decodingTable[data.charAt(i++)];
while ((i < finish) && ignore(data.charAt(i)))
{
i++;
}
b4 = decodingTable[data.charAt(i++)];
out.write((b1 << 2) | (b2 >> 4));
out.write((b2 << 4) | (b3 >> 2));
out.write((b3 << 6) | b4);
length += 3;
}
if (data.charAt(end - 2) == padding)
{
b1 = decodingTable[data.charAt(end - 4)];
b2 = decodingTable[data.charAt(end - 3)];
out.write((b1 << 2) | (b2 >> 4));
length += 1;
}
else if (data.charAt(end - 1) == padding)
{
b1 = decodingTable[data.charAt(end - 4)];
b2 = decodingTable[data.charAt(end - 3)];
b3 = decodingTable[data.charAt(end - 2)];
out.write((b1 << 2) | (b2 >> 4));
out.write((b2 << 4) | (b3 >> 2));
length += 2;
}
else
{
b1 = decodingTable[data.charAt(end - 4)];
b2 = decodingTable[data.charAt(end - 3)];
b3 = decodingTable[data.charAt(end - 2)];
b4 = decodingTable[data.charAt(end - 1)];
out.write((b1 << 2) | (b2 >> 4));
out.write((b2 << 4) | (b3 >> 2));
out.write((b3 << 6) | b4);
length += 3;
}
return length;
}
/**
* decode the base 64 encoded byte data writing it to the provided byte array buffer.
*
* @return the number of bytes produced.
*/
public int decode(byte[] data, int off, int length, byte[] out) throws IOException
{
byte[] bytes;
byte b1, b2, b3, b4;
int outLen = 0;
int end = off + length;
while (end > 0)
{
if (!ignore((char)data[end - 1]))
{
break;
}
end--;
}
int i = off;
int finish = end - 4;
while (i < finish)
{
while ((i < finish) && ignore((char)data[i]))
{
i++;
}
b1 = decodingTable[data[i++]];
while ((i < finish) && ignore((char)data[i]))
{
i++;
}
b2 = decodingTable[data[i++]];
while ((i < finish) && ignore((char)data[i]))
{
i++;
}
b3 = decodingTable[data[i++]];
while ((i < finish) && ignore((char)data[i]))
{
i++;
}
b4 = decodingTable[data[i++]];
out[outLen++] = (byte)((b1 << 2) | (b2 >> 4));
out[outLen++] = (byte)((b2 << 4) | (b3 >> 2));
out[outLen++] = (byte)((b3 << 6) | b4);
}
if (data[end - 2] == padding)
{
b1 = decodingTable[data[end - 4]];
b2 = decodingTable[data[end - 3]];
out[outLen++] = (byte)((b1 << 2) | (b2 >> 4));
}
else if (data[end - 1] == padding)
{
b1 = decodingTable[data[end - 4]];
b2 = decodingTable[data[end - 3]];
b3 = decodingTable[data[end - 2]];
out[outLen++] = (byte)((b1 << 2) | (b2 >> 4));
out[outLen++] = (byte)((b2 << 4) | (b3 >> 2));
}
else
{
b1 = decodingTable[data[end - 4]];
b2 = decodingTable[data[end - 3]];
b3 = decodingTable[data[end - 2]];
b4 = decodingTable[data[end - 1]];
out[outLen++] = (byte)((b1 << 2) | (b2 >> 4));
out[outLen++] = (byte)((b2 << 4) | (b3 >> 2));
out[outLen++] = (byte)((b3 << 6) | b4);
}
return outLen;
}
/**
* Test if a character is a valid Base64 encoding character. This
* must be either a valid digit or the padding character ("=").
*
* @param ch The test character.
*
* @return true if this is valid in Base64 encoded data, false otherwise.
*/
public boolean isValidBase64(int ch) {
// 'A' has the value 0 in the decoding table, so we need a special one for that
return ch == padding || ch == 'A' || decodingTable[ch] != 0;
}
/**
* Perform RFC-2047 word encoding using Base64 data encoding.
*
* @param in The source for the encoded data.
* @param charset The charset tag to be added to each encoded data section.
* @param out The output stream where the encoded data is to be written.
* @param fold Controls whether separate sections of encoded data are separated by
* linebreaks or whitespace.
*
* @exception IOException
*/
public void encodeWord(InputStream in, String charset, OutputStream out, boolean fold) throws IOException
{
PrintStream writer = new PrintStream(out);
// encoded words are restricted to 76 bytes, including the control adornments.
int limit = 75 - 7 - charset.length();
boolean firstLine = true;
StringBuffer encodedString = new StringBuffer(76);
while (true) {
// encode the next segment.
encode(in, encodedString, limit);
// if we're out of data, nothing will be encoded.
if (encodedString.length() == 0) {
break;
}
// if we have more than one segment, we need to insert separators. Depending on whether folding
// was requested, this is either a blank or a linebreak.
if (!firstLine) {
if (fold) {
writer.print("\r\n");
}
else {
writer.print(" ");
}
}
// add the encoded word header
writer.print("=?");
writer.print(charset);
writer.print("?B?");
// the data
writer.print(encodedString.toString());
// and the word terminator.
writer.print("?=");
writer.flush();
// reset our string buffer for the next segment.
encodedString.setLength(0);
// we need a delimiter after this
firstLine = false;
}
}
/**
* Perform RFC-2047 word encoding using Base64 data encoding.
*
* @param in The source for the encoded data.
* @param charset The charset tag to be added to each encoded data section.
* @param out The output stream where the encoded data is to be written.
* @param fold Controls whether separate sections of encoded data are separated by
* linebreaks or whitespace.
*
* @exception IOException
*/
public void encodeWord(byte[] data, StringBuffer out, String charset) throws IOException
{
// append the word header
out.append("=?");
out.append(charset);
out.append("?B?");
// add on the encodeded data
encodeWordData(data, out);
// the end of the encoding marker
out.append("?=");
}
/**
* encode the input data producing a base 64 output stream.
*
* @return the number of bytes produced.
*/
public void encodeWordData(byte[] data, StringBuffer out)
{
int modulus = data.length % 3;
int dataLength = (data.length - modulus);
int a1, a2, a3;
for (int i = 0; i < dataLength; i += 3)
{
a1 = data[i] & 0xff;
a2 = data[i + 1] & 0xff;
a3 = data[i + 2] & 0xff;
out.append((char)encodingTable[(a1 >>> 2) & 0x3f]);
out.append((char)encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3f]);
out.append((char)encodingTable[((a2 << 2) | (a3 >>> 6)) & 0x3f]);
out.append((char)encodingTable[a3 & 0x3f]);
}
/*
* process the tail end.
*/
int b1, b2, b3;
int d1, d2;
switch (modulus)
{
case 0: /* nothing left to do */
break;
case 1:
d1 = data[dataLength] & 0xff;
b1 = (d1 >>> 2) & 0x3f;
b2 = (d1 << 4) & 0x3f;
out.append((char)encodingTable[b1]);
out.append((char)encodingTable[b2]);
out.append((char)padding);
out.append((char)padding);
break;
case 2:
d1 = data[dataLength] & 0xff;
d2 = data[dataLength + 1] & 0xff;
b1 = (d1 >>> 2) & 0x3f;
b2 = ((d1 << 4) | (d2 >>> 4)) & 0x3f;
b3 = (d2 << 2) & 0x3f;
out.append((char)encodingTable[b1]);
out.append((char)encodingTable[b2]);
out.append((char)encodingTable[b3]);
out.append((char)padding);
break;
}
}
/**
* encode the input data producing a base 64 output stream.
*
* @return the number of bytes produced.
*/
public void encode(InputStream in, StringBuffer out, int limit) throws IOException
{
int count = limit / 4;
byte [] inBuffer = new byte[3];
while (count-- > 0) {
int readCount = in.read(inBuffer);
// did we get a full triplet? that's an easy encoding.
if (readCount == 3) {
int a1 = inBuffer[0] & 0xff;
int a2 = inBuffer[1] & 0xff;
int a3 = inBuffer[2] & 0xff;
out.append((char)encodingTable[(a1 >>> 2) & 0x3f]);
out.append((char)encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3f]);
out.append((char)encodingTable[((a2 << 2) | (a3 >>> 6)) & 0x3f]);
out.append((char)encodingTable[a3 & 0x3f]);
}
else if (readCount <= 0) {
// eof condition, don'e entirely.
return;
}
else if (readCount == 1) {
int a1 = inBuffer[0] & 0xff;
out.append((char)encodingTable[(a1 >>> 2) & 0x3f]);
out.append((char)encodingTable[(a1 << 4) & 0x3f]);
out.append((char)padding);
out.append((char)padding);
return;
}
else if (readCount == 2) {
int a1 = inBuffer[0] & 0xff;
int a2 = inBuffer[1] & 0xff;
out.append((char)encodingTable[(a1 >>> 2) & 0x3f]);
out.append((char)encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3f]);
out.append((char)encodingTable[(a2 << 2) & 0x3f]);
out.append((char)padding);
return;
}
}
}
/**
* Estimate the final encoded size of a segment of data.
* This is used to ensure that the encoded blocks do
* not get split across a unicode character boundary and
* that the encoding will fit within the bounds of
* a mail header line.
*
* @param data The data we're anticipating encoding.
*
* @return The size of the byte data in encoded form.
*/
public int estimateEncodedLength(byte[] data)
{
return ((data.length + 2) / 3) * 4;
}
}
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