gecko-dev/grendel/mime/encoder/MimeQuotedPrintableDecoder....

165 строки
6.3 KiB
Java

/* -*- Mode: java; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.0 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* The Original Code is the Grendel mail/news client.
*
* The Initial Developer of the Original Code is Netscape Communications
* Corporation. Portions created by Netscape are Copyright (C) 1997
* Netscape Communications Corporation. All Rights Reserved.
*
* Created: Jamie Zawinski <jwz@netscape.com>, 28 Aug 1997.
*/
package grendel.mime.encoder;
import calypso.util.ByteBuf;
/** Implements a Quoted-Printable -> plaintext decoder.
*/
public class MimeQuotedPrintableDecoder extends MimeEncoder {
private byte token[] = new byte[3]; // input and output buffer
private int token_length = 0; // input buffer length
static private final byte NUL = 127; // must be greater than 16
static private final byte ESC = 126; // must be greater than 16
static private final byte CR = 125; // must be greater than 16
static private final byte LF = 124; // must be greater than 16
static private final byte map[] = {
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 000-007
NUL, NUL, LF, NUL, NUL, CR, NUL, NUL, // 010-017
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 020-027
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 030-037
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 040-047 !"#$%&'
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 050-057 ()*+,-./
0, 1, 2, 3, 4, 5, 6, 7, // 060-067 01234567
8, 9, NUL, NUL, NUL, ESC, NUL, NUL, // 070-077 89:;<=>?
NUL, 10, 11, 12, 13, 14, 15, NUL, // 100-107 @ABCDEFG
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 110-117 HIJKLMNO
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 120-127 PQRSTUVW
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 130-137 XYZ[\]^_
NUL, 10, 11, 12, 13, 14, 15, NUL, // 140-147 `abcdefg
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 150-157 hijklmno
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 160-167 pqrstuvw
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 170-177 xyz{|}~
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 200-207
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 210-217
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 220-227
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 230-237
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 240-247
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 250-257
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 260-267
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 270-277
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 300-307
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 310-317
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 320-327
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 330-337
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 340-347
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 350-357
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 360-367
NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 370-377
};
/** Given a sequence of input bytes using the quoted-printable encoding,
produces a sequence of unencoded output bytes. Note that some (small)
amount of buffering may be necessary, if the input byte stream didn't
fall on an appropriate boundary. If there are bytes in `out' already,
the new bytes are appended, so the caller should do `out.setLength(0)'
first if that's desired.
*/
public final void translate(ByteBuf in, ByteBuf out) {
/* To Do, maybe someday: when decoding quoted-printable, we are required
to strip trailing whitespace from lines -- since when encoding in QP,
one is required to quote such trailing whitespace, any trailing
whitespace which remains must have been introduced by a stupid gateway.
We don't do this right now, as it would require arbitrary lookahead
instead of just a fixed distance of three bytes.
*/
byte inb[] = in.toBytes();
int in_length = in.length();
int i = 0;
while (i < in_length) {
// First, copy as many consecutive bytes as we can.
if (token_length == 0) {
int j = i;
while (i < in_length && map[inb[i]] != ESC)
i++;
if (i != j)
out.append(inb, j, i-j);
if (i >= in_length)
break;
}
// at this point, either token_length > 0, or we've seen ESC
byte b = inb[i];
byte c = map[b];
i++;
token[token_length++] = b;
if (token_length != 3)
continue;
token_length = 0;
// assert (map[token[0]] == ESC)
byte n1 = map[token[1]];
byte n2 = map[token[2]];
if (n1 == CR || n1 == LF) { // "=\r", "=\n", or "=\r\n"
if (n1 == LF || n2 != LF) {
// lone CR or LF -- push out or put back following character.
if (n2 == ESC) {
token[0] = token[2];
token_length = 1;
} else {
out.append(token[2]);
}
}
} else if (n1 <= 15 || n2 <= 15) { // "=xy" where x and y are hex
out.append((byte) ((n1 << 4) | n2));
} else { // something unparsable.
out.append(token); // write it out unchanged.
}
}
}
/** Tell the quoted-printable decoder that no more input data will be
forthcoming. This may result in output, as a result of flushing the
internal buffer. This object must not be used again after calling eof().
If there are bytes in `out' already, the new bytes are appended,
so the caller should do `out.setLength(0)' first if that's desired.
*/
public final void eof(ByteBuf out) {
// ignore the last incomplete token, if any -- it means "no trailing CRLF".
token_length = 0;
token = null;
}
}