124 lines
4.1 KiB
Java
124 lines
4.1 KiB
Java
/* -*- Mode: java; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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*
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* The contents of this file are subject to the Mozilla Public License
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* Version 1.0 (the "License"); you may not use this file except in
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* compliance with the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS"
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* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
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* the License for the specific language governing rights and limitations
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* under the License.
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*
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* The Original Code is the Grendel mail/news client.
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*
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* The Initial Developer of the Original Code is Netscape Communications
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* Corporation. Portions created by Netscape are Copyright (C) 1997
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* Netscape Communications Corporation. All Rights Reserved.
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*
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* Created: Jamie Zawinski <jwz@netscape.com>, 28 Aug 1997.
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*/
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package grendel.mime.encoder;
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import calypso.util.ByteBuf;
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/** Implements a Base64 -> plaintext decoder.
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*/
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public final class MimeBase64Encoder extends MimeEncoder {
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private int buf = 0; // a 24-bit quantity
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private int buf_bytes = 0; // how many octets are set in it
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private byte line[] = new byte[74]; // output buffer
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private int line_length = 0; // output buffer fill pointer
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static private final byte crlf[] = "\r\n".getBytes();
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static private final byte map[] = {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', // 0-7
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'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', // 8-15
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', // 16-23
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'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', // 24-31
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'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', // 32-39
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'o', 'p', 'q', 'r', 's', 't', 'u', 'v', // 40-47
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'w', 'x', 'y', 'z', '0', '1', '2', '3', // 48-55
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'4', '5', '6', '7', '8', '9', '+', '/', // 56-63
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};
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private final void encode_token() {
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int i = line_length;
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line[i] = map[0x3F & (buf >> 18)]; // sextet 1 (octet 1)
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line[i+1] = map[0x3F & (buf >> 12)]; // sextet 2 (octet 1 and 2)
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line[i+2] = map[0x3F & (buf >> 6)]; // sextet 3 (octet 2 and 3)
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line[i+3] = map[0x3F & buf]; // sextet 4 (octet 3)
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line_length += 4;
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buf = 0;
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buf_bytes = 0;
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}
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private final void encode_partial_token() {
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int i = line_length;
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line[i] = map[0x3F & (buf >> 18)]; // sextet 1 (octet 1)
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line[i+1] = map[0x3F & (buf >> 12)]; // sextet 2 (octet 1 and 2)
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if (buf_bytes == 1)
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line[i+2] = '=';
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else
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line[i+2] = map[0x3F & (buf >> 6)]; // sextet 3 (octet 2 and 3)
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if (buf_bytes <= 2)
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line[i+3] = '=';
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else
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line[i+3] = map[0x3F & buf]; // sextet 4 (octet 3)
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line_length += 4;
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buf = 0;
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buf_bytes = 0;
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}
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private final void flush_line(ByteBuf out) {
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line[line_length] = '\r';
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line[line_length+1] = '\n';
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out.append(line, 0, line_length + 2);
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line_length = 0;
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}
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/** Given a sequence of input bytes, produces a sequence of output bytes
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using the base64 encoding. If there are bytes in `out' already, the
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new bytes are appended, so the caller should do `out.setLength(0)'
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first if that's desired.
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*/
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public final void translate(ByteBuf in, ByteBuf out) {
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byte inb[] = in.toBytes();
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int in_length = in.length();
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for (int i = 0; i < in_length; i++) {
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if (buf_bytes == 0)
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buf = (buf & 0x00FFFF) | (inb[i] << 16);
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else if (buf_bytes == 1)
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buf = (buf & 0xFF00FF) | (inb[i] << 8);
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else
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buf = (buf & 0xFFFF00) | (inb[i]);
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if ((++buf_bytes) == 3) {
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encode_token();
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if (line_length >= 72)
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flush_line(out);
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}
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}
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}
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/** Tell the base64 encoder that no more input data will be forthcoming.
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This may result in output, as a result of flushing the internal buffer.
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This object must not be used again after calling eof(). If there are
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bytes in `out' already, the new bytes are appended, so the caller should
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do `out.setLength(0)' first if that's desired.
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*/
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public final void eof(ByteBuf out) {
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if (buf_bytes != 0)
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encode_partial_token();
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flush_line(out);
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line = null;
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}
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}
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