File indexing completed on 2024-04-21 03:53:01

 /*  -*- c++ -*-
     SPDX-FileCopyrightText: 2001-2002 Marc Mutz <mutz@kde.org>
 
     SPDX-License-Identifier: LGPL-2.0-or-later
 */
 /**
   @file
   This file is part of the API for handling @ref MIME data and
   defines the @ref Base64 and @ref RFC2047B @ref Codec classes.
 
   @brief
   Defines the Base64Codec and Rfc2047BEncodingCodec classes.
 
   @authors Marc Mutz \<mutz@kde.org\>
 
   @glossary @anchor Base64 @anchor base64 @b base64:
   a binary to text encoding scheme based on @ref RFC1421.
 
   @glossary @anchor RFC1421 @anchor rfc1421 @b RFC @b 1421:
   RFC that defines the <a href="http://tools.ietf.org/html/rfc1421">
   Privacy Enhancement for Internet Electronic Mail:  Part I:
   Message Encryption and Authentication Procedures</a>.
 
   @glossary @anchor RFC2045 @anchor rfc2045 @b RFC @b 2045:
   RFC that defines the <a href="http://tools.ietf.org/html/rfc2045">
   MIME Part One: Format of Internet Message Bodies</a>.
 
   @glossary @anchor RFC2047 @anchor rfc2047 @b RFC @b 2047:
   RFC that defines the <a href="http://tools.ietf.org/html/rfc2047">
   MIME Part Three: Message Header Extensions for Non-ASCII Text</a>.
 
   @glossary @anchor RFC2047B @anchor rfc2047b @b RFC @b 2047B:
   Section 4.1 of @ref RFC2047.
 */
 
 #ifndef KCODECS_BASE64_H
 #define KCODECS_BASE64_H
 
 #include "kcodecs.h"
 
 namespace KCodecs
 {
 /**
   @brief
   A class representing the @ref codec for @ref Base64 as specified in
   @ref RFC2045
 */
 class Base64Codec : public Codec
 {
 public:
     /**
       Constructs a Base64 codec.
     */
     Base64Codec()
         : Codec()
     {
     }
 
     /**
       Destroys the codec.
     */
     ~Base64Codec() override
     {
     }
 
     /**
       @copydoc
       Codec::name()
     */
     const char *name() const override
     {
         return "base64";
     }
 
     /**
       @copydoc
       Codec::maxEncodedSizeFor()
     */
     qsizetype maxEncodedSizeFor(qsizetype insize, NewlineType newline) const override
     {
         // first, the total number of 4-char packets will be:
         qsizetype totalNumPackets = (insize + 2) / 3;
         // now, after every 76/4'th packet there needs to be a linebreak:
         qsizetype numLineBreaks = totalNumPackets / (76 / 4);
         // and at the very end, too:
         ++numLineBreaks;
         // putting it all together, we have:
         return 4 * totalNumPackets + (newline == Codec::NewlineCRLF ? 2 : 1) * numLineBreaks;
     }
 
     /**
       @copydoc
       Codec::maxDecodedSizeFor()
     */
     qsizetype maxDecodedSizeFor(qsizetype insize, NewlineType newline = Codec::NewlineLF) const override
     {
         // assuming all characters are part of the base64 stream (which
         // does almost never hold due to required linebreaking; but
         // additional non-base64 chars don't affect the output size), each
         // 4-tupel of them becomes a 3-tupel in the decoded octet
         // stream. So:
         qsizetype result = ((insize + 3) / 4) * 3;
         // but all of them may be \n, so
         if (newline == Codec::NewlineCRLF) {
             result *= 2; // :-o
         }
 
         return result;
     }
 
     /**
       @copydoc
       Codec::makeEncoder()
     */
     Encoder *makeEncoder(NewlineType newline = Codec::NewlineLF) const override;
 
     /**
       @copydoc
       Codec::makeDecoder()
     */
     Decoder *makeDecoder(NewlineType newline = Codec::NewlineLF) const override;
 };
 
 /**
   @brief
   A class representing the @ref codec for the B encoding as specified
   in @ref RFC2047B.
 */
 class Rfc2047BEncodingCodec : public Base64Codec
 {
 public:
     /**
       Constructs a RFC2047B codec.
     */
     Rfc2047BEncodingCodec()
         : Base64Codec()
     {
     }
 
     /**
       Destroys the codec.
     */
     ~Rfc2047BEncodingCodec() override
     {
     }
 
     /**
       @copydoc
       Codec::name()
     */
     const char *name() const override
     {
         return "b";
     }
 
     /**
       @copydoc
       Codec::maxEncodedSizeFor()
     */
     qsizetype maxEncodedSizeFor(qsizetype insize, NewlineType newline = Codec::NewlineLF) const override
     {
         Q_UNUSED(newline);
         // Each (begun) 3-octet triple becomes a 4 char quartet, so:
         return ((insize + 2) / 3) * 4;
     }
 
     /**
       @copydoc
       Codec::maxDecodedSizeFor()
     */
     qsizetype maxDecodedSizeFor(qsizetype insize, NewlineType newline = Codec::NewlineLF) const override
     {
         Q_UNUSED(newline);
         // Each 4-char quartet becomes a 3-octet triple, the last one
         // possibly even less. So:
         return ((insize + 3) / 4) * 3;
     }
 
     /**
       @copydoc
       Codec::makeEncoder()
     */
     Encoder *makeEncoder(NewlineType newline = Codec::NewlineLF) const override;
 };
 
 } // namespace KCodecs
 
 #endif // KCODECS_BASE64_H