File indexing completed on 2024-04-28 07:41:31

 /*
     SPDX-FileCopyrightText: 2000-2001 Dawit Alemayehu <adawit@kde.org>
     SPDX-FileCopyrightText: 2001 Rik Hemsley (rikkus) <rik@kde.org>
     SPDX-FileCopyrightText: 2001-2002 Marc Mutz <mutz@kde.org>
 
     SPDX-License-Identifier: LGPL-2.0-only
 
     The encoding and decoding utilities in KCodecs with the exception of
     quoted-printable are based on the java implementation in HTTPClient
     package by Ronald Tschalär Copyright (C) 1996-1999.                          // krazy:exclude=copyright
 
     The quoted-printable codec as described in RFC 2045, section 6.7. is by
     Rik Hemsley (C) 2001.
 */
 
 #include "kcodecs.h"
 #include "kcharsets.h"
 #include "kcharsets_p.h"
 #include "kcodecs_debug.h"
 #include "kcodecs_p.h"
 #include "kcodecsbase64.h"
 #include "kcodecsqp.h"
 #include "kcodecsuuencode.h"
 
 #include <array>
 #include <cassert>
 #include <cstring>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include <QDebug>
 #include <QStringDecoder>
 #include <QStringEncoder>
 
 #if defined(Q_OS_WIN)
 #define strncasecmp _strnicmp
 #endif
 
 namespace KCodecs
 {
 static QList<QByteArray> charsetCache;
 
 QByteArray cachedCharset(const QByteArray &name)
 {
     auto it = std::find_if(charsetCache.cbegin(), charsetCache.cend(), [&name](const QByteArray &charset) {
         return qstricmp(name.data(), charset.data()) == 0;
     });
     if (it != charsetCache.cend()) {
         return *it;
     }
 
     charsetCache.append(name.toUpper());
     return charsetCache.last();
 }
 
 namespace CodecNames
 {
 QByteArray utf8()
 {
     return QByteArrayLiteral("UTF-8");
 }
 }
 
 Q_REQUIRED_RESULT
 QByteArray updateEncodingCharset(const QByteArray &currentCharset, const QByteArray &nextCharset)
 {
     if (!nextCharset.isEmpty()) {
         if (currentCharset.isEmpty()) {
             return nextCharset;
         }
         if (currentCharset != nextCharset) {
             // only one charset per string supported, so change to superset charset UTF-8,
             // which should  cover any possible chars
             return CodecNames::utf8();
         }
     }
     return currentCharset;
 }
 
 } // namespace KCodecs
 
 /******************************** KCodecs ********************************/
 
 QByteArray KCodecs::quotedPrintableEncode(QByteArrayView in, bool useCRLF)
 {
     Codec *codec = Codec::codecForName("quoted-printable");
     return codec->encode(in, useCRLF ? Codec::NewlineCRLF : Codec::NewlineLF);
 }
 
 void KCodecs::quotedPrintableEncode(QByteArrayView in, QByteArray &out, bool useCRLF)
 {
     out = quotedPrintableEncode(in, useCRLF ? Codec::NewlineCRLF : Codec::NewlineLF);
 }
 
 QByteArray KCodecs::quotedPrintableDecode(QByteArrayView in)
 {
     Codec *codec = Codec::codecForName("quoted-printable");
     return codec->decode(in);
 }
 
 void KCodecs::quotedPrintableDecode(QByteArrayView in, QByteArray &out)
 {
     out = quotedPrintableDecode(in);
 }
 
 QByteArray KCodecs::base64Encode(QByteArrayView in)
 {
     Codec *codec = Codec::codecForName("base64");
     return codec->encode(in);
 }
 
 void KCodecs::base64Encode(QByteArrayView in, QByteArray &out, bool insertLFs)
 {
     Q_UNUSED(insertLFs);
     out = base64Encode(in);
 }
 
 QByteArray KCodecs::base64Decode(QByteArrayView in)
 {
     Codec *codec = Codec::codecForName("base64");
     return codec->decode(in);
 }
 
 void KCodecs::base64Decode(const QByteArrayView in, QByteArray &out)
 {
     out = base64Decode(in);
 }
 
 QByteArray KCodecs::uudecode(QByteArrayView in)
 {
     Codec *codec = Codec::codecForName("x-uuencode");
     return codec->decode(in);
 }
 
 void KCodecs::uudecode(QByteArrayView in, QByteArray &out)
 {
     out = uudecode(in);
 }
 
 //@cond PRIVATE
 
 namespace KCodecs
 {
 // parse the encoded-word (scursor points to after the initial '=')
 bool parseEncodedWord(const char *&scursor,
                       const char *const send,
                       QString *result,
                       QByteArray *language,
                       QByteArray *usedCS,
                       const QByteArray &defaultCS,
                       CharsetOption charsetOption)
 {
     assert(result);
     assert(language);
 
     // make sure the caller already did a bit of the work.
     assert(*(scursor - 1) == '=');
 
     //
     // STEP 1:
     // scan for the charset/language portion of the encoded-word
     //
 
     char ch = *scursor++;
 
     if (ch != '?') {
         // qCDebug(KCODECS_LOG) << "first";
         // qCDebug(KCODECS_LOG) << "Premature end of encoded word";
         return false;
     }
 
     // remember start of charset (i.e. just after the initial "=?") and
     // language (just after the first '*') fields:
     const char *charsetStart = scursor;
     const char *languageStart = nullptr;
 
     // find delimiting '?' (and the '*' separating charset and language
     // tags, if any):
     for (; scursor != send; scursor++) {
         if (*scursor == '?') {
             break;
         } else if (*scursor == '*' && languageStart == nullptr) {
             languageStart = scursor + 1;
         }
     }
 
     // not found? can't be an encoded-word!
     if (scursor == send || *scursor != '?') {
         // qCDebug(KCODECS_LOG) << "second";
         // qCDebug(KCODECS_LOG) << "Premature end of encoded word";
         return false;
     }
 
     // extract the language information, if any (if languageStart is 0,
     // language will be null, too):
     QByteArray maybeLanguage(languageStart, scursor - languageStart);
     // extract charset information (keep in mind: the size given to the
     // ctor is one off due to the \0 terminator):
     QByteArray maybeCharset(charsetStart, (languageStart ? languageStart - 1 : scursor) - charsetStart);
 
     //
     // STEP 2:
     // scan for the encoding portion of the encoded-word
     //
 
     // remember start of encoding (just _after_ the second '?'):
     scursor++;
     const char *encodingStart = scursor;
 
     // find next '?' (ending the encoding tag):
     for (; scursor != send; scursor++) {
         if (*scursor == '?') {
             break;
         }
     }
 
     // not found? Can't be an encoded-word!
     if (scursor == send || *scursor != '?') {
         // qCDebug(KCODECS_LOG) << "third";
         // qCDebug(KCODECS_LOG) << "Premature end of encoded word";
         return false;
     }
 
     // extract the encoding information:
     QByteArray maybeEncoding(encodingStart, scursor - encodingStart);
 
     // qCDebug(KCODECS_LOG) << "parseEncodedWord: found charset == \"" << maybeCharset
     //         << "\"; language == \"" << maybeLanguage
     //         << "\"; encoding == \"" << maybeEncoding << "\"";
 
     //
     // STEP 3:
     // scan for encoded-text portion of encoded-word
     //
 
     // remember start of encoded-text (just after the third '?'):
     scursor++;
     const char *encodedTextStart = scursor;
 
     // find the '?=' sequence (ending the encoded-text):
     for (; scursor != send; scursor++) {
         if (*scursor == '?') {
             if (scursor + 1 != send) {
                 if (*(scursor + 1) != '=') { // We expect a '=' after the '?', but we got something else; ignore
                     // qCDebug(KCODECS_LOG) << "Stray '?' in q-encoded word, ignoring this.";
                     continue;
                 } else { // yep, found a '?=' sequence
                     scursor += 2;
                     break;
                 }
             } else { // The '?' is the last char, but we need a '=' after it!
                 // qCDebug(KCODECS_LOG) << "Premature end of encoded word";
                 return false;
             }
         }
     }
 
     if (*(scursor - 2) != '?' || *(scursor - 1) != '=' || scursor < encodedTextStart + 2) {
         // qCDebug(KCODECS_LOG) << "Premature end of encoded word";
         return false;
     }
 
     // set end sentinel for encoded-text:
     const char *const encodedTextEnd = scursor - 2;
 
     //
     // STEP 4:
     // setup decoders for the transfer encoding and the charset
     //
 
     // try if there's a codec for the encoding found:
     Codec *codec = Codec::codecForName(maybeEncoding);
     if (!codec) {
         // qCDebug(KCODECS_LOG) << "Unknown encoding" << maybeEncoding;
         return false;
     }
 
     // get an instance of a corresponding decoder:
     Decoder *dec = codec->makeDecoder();
     assert(dec);
 
     // try if there's a (text)codec for the charset found:
     QByteArray cs;
     QStringDecoder textCodec;
     if (charsetOption == KCodecs::ForceDefaultCharset || maybeCharset.isEmpty()) {
         textCodec = QStringDecoder(defaultCS.constData());
         cs = cachedCharset(defaultCS);
     } else {
         textCodec = QStringDecoder(maybeCharset.constData());
         if (!textCodec.isValid()) { // no suitable codec found => use default charset
             textCodec = QStringDecoder(defaultCS.constData());
             cs = cachedCharset(defaultCS);
         } else {
             cs = cachedCharset(maybeCharset);
         }
     }
     if (usedCS) {
         *usedCS = updateEncodingCharset(*usedCS, cs);
     }
 
     if (!textCodec.isValid()) {
         // qCDebug(KCODECS_LOG) << "Unknown charset" << maybeCharset;
         delete dec;
         return false;
     };
 
     // qCDebug(KCODECS_LOG) << "mimeName(): \"" << textCodec->name() << "\"";
 
     // allocate a temporary buffer to store the 8bit text:
     int encodedTextLength = encodedTextEnd - encodedTextStart;
     QByteArray buffer;
     buffer.resize(codec->maxDecodedSizeFor(encodedTextLength));
     char *bbegin = buffer.data();
     char *bend = bbegin + buffer.length();
 
     //
     // STEP 5:
     // do the actual decoding
     //
 
     if (!dec->decode(encodedTextStart, encodedTextEnd, bbegin, bend)) {
         qWarning() << codec->name() << "codec lies about its maxDecodedSizeFor(" << encodedTextLength << ")\nresult may be truncated";
     }
 
     *result = textCodec.decode(QByteArrayView(buffer.data(), bbegin - buffer.data()));
 
     // qCDebug(KCODECS_LOG) << "result now: \"" << result << "\"";
     // cleanup:
     delete dec;
     *language = maybeLanguage;
 
     return true;
 }
 
 } // namespace KCodecs
 
 //@endcond
 
 QString KCodecs::decodeRFC2047String(QStringView msg)
 {
     QByteArray usedCS;
     return decodeRFC2047String(msg.toUtf8(), &usedCS, CodecNames::utf8(), NoOption);
 }
 
 QString KCodecs::decodeRFC2047String(QByteArrayView src, QByteArray *usedCS, const QByteArray &defaultCS, CharsetOption charsetOption)
 {
     QByteArray result;
     QByteArray spaceBuffer;
     const char *scursor = src.constData();
     const char *send = scursor + src.length();
     bool onlySpacesSinceLastWord = false;
     if (usedCS) {
         usedCS->clear();
     }
 
     while (scursor != send) {
         // space
         if (isspace(*scursor) && onlySpacesSinceLastWord) {
             spaceBuffer += *scursor++;
             continue;
         }
 
         // possible start of an encoded word
         if (*scursor == '=') {
             QByteArray language;
             QString decoded;
             ++scursor;
             const char *start = scursor;
             if (parseEncodedWord(scursor, send, &decoded, &language, usedCS, defaultCS, charsetOption)) {
                 result += decoded.toUtf8();
                 onlySpacesSinceLastWord = true;
                 spaceBuffer.clear();
             } else {
                 if (onlySpacesSinceLastWord) {
                     result += spaceBuffer;
                     onlySpacesSinceLastWord = false;
                 }
                 result += '=';
                 scursor = start; // reset cursor after parsing failure
             }
             continue;
         } else {
             // unencoded data
             if (onlySpacesSinceLastWord) {
                 result += spaceBuffer;
                 onlySpacesSinceLastWord = false;
             }
             result += *scursor;
             ++scursor;
         }
     }
     // If there are any chars that couldn't be decoded in UTF-8,
     // fallback to local codec
     const QString tryUtf8 = QString::fromUtf8(result);
     if (tryUtf8.contains(QChar(0xFFFD))) {
         QStringDecoder codec(QStringDecoder::System);
         if (usedCS) {
             *usedCS = updateEncodingCharset(*usedCS, cachedCharset(codec.name()));
         }
         return codec.decode(result);
     } else {
         return tryUtf8;
     }
 }
 
 QByteArray KCodecs::encodeRFC2047String(QStringView src, const QByteArray &charset)
 {
     QByteArray result;
     int start = 0;
     int end = 0;
     bool nonAscii = false;
     bool useQEncoding = false;
 
     QStringEncoder codec(charset.constData());
 
     QByteArray usedCS;
     if (!codec.isValid()) {
         // no codec available => try local8Bit and hope the best ;-)
         codec = QStringEncoder(QStringEncoder::System);
         usedCS = codec.name();
     } else {
         Q_ASSERT(codec.isValid());
         if (charset.isEmpty()) {
             usedCS = codec.name();
         } else {
             usedCS = charset;
         }
     }
 
     QByteArray encoded8Bit = codec.encode(src);
     if (codec.hasError()) {
         usedCS = CodecNames::utf8();
         codec = QStringEncoder(QStringEncoder::Utf8);
         encoded8Bit = codec.encode(src);
     }
 
     if (usedCS.contains("8859-")) { // use "B"-Encoding for non iso-8859-x charsets
         useQEncoding = true;
     }
 
     uint encoded8BitLength = encoded8Bit.length();
     for (unsigned int i = 0; i < encoded8BitLength; i++) {
         if (encoded8Bit[i] == ' ') { // encoding starts at word boundaries
             start = i + 1;
         }
 
         // encode escape character, for japanese encodings...
         if (((signed char)encoded8Bit[i] < 0) || (encoded8Bit[i] == '\033')) {
             end = start; // non us-ascii char found, now we determine where to stop encoding
             nonAscii = true;
             break;
         }
     }
 
     if (nonAscii) {
         while ((end < encoded8Bit.length()) && (encoded8Bit[end] != ' ')) {
             // we encode complete words
             end++;
         }
 
         for (int x = end; x < encoded8Bit.length(); x++) {
             if (((signed char)encoded8Bit[x] < 0) || (encoded8Bit[x] == '\033')) {
                 end = x; // we found another non-ascii word
 
                 while ((end < encoded8Bit.length()) && (encoded8Bit[end] != ' ')) {
                     // we encode complete words
                     end++;
                 }
             }
         }
 
         result = encoded8Bit.left(start) + "=?" + usedCS;
 
         if (useQEncoding) {
             result += "?Q?";
 
             char hexcode; // "Q"-encoding implementation described in RFC 2047
             for (int i = start; i < end; i++) {
                 const char c = encoded8Bit[i];
                 if (c == ' ') { // make the result readable with not MIME-capable readers
                     result += '_';
                 } else {
                     if (((c >= 'a') && (c <= 'z')) || // paranoid mode, encode *all* special chars to avoid problems
                         ((c >= 'A') && (c <= 'Z')) || // with "From" & "To" headers
                         ((c >= '0') && (c <= '9'))) {
                         result += c;
                     } else {
                         result += '='; // "stolen" from KMail ;-)
                         hexcode = ((c & 0xF0) >> 4) + 48;
                         if (hexcode >= 58) {
                             hexcode += 7;
                         }
                         result += hexcode;
                         hexcode = (c & 0x0F) + 48;
                         if (hexcode >= 58) {
                             hexcode += 7;
                         }
                         result += hexcode;
                     }
                 }
             }
         } else {
             result += "?B?" + encoded8Bit.mid(start, end - start).toBase64();
         }
 
         result += "?=";
         result += encoded8Bit.right(encoded8Bit.length() - end);
     } else {
         result = encoded8Bit;
     }
 
     return result;
 }
 
 /******************************************************************************/
 /*                           KCodecs::Codec                                   */
 
 KCodecs::Codec *KCodecs::Codec::codecForName(QByteArrayView name)
 {
     struct CodecEntry {
         const char *name;
         std::unique_ptr<KCodecs::Codec> codec;
     };
     // ### has to be sorted by name!
     static const std::array<CodecEntry, 6> s_codecs{{
         {"b", std::make_unique<KCodecs::Rfc2047BEncodingCodec>()},
         {"base64", std::make_unique<KCodecs::Base64Codec>()},
         {"q", std::make_unique<KCodecs::Rfc2047QEncodingCodec>()},
         {"quoted-printable", std::make_unique<KCodecs::QuotedPrintableCodec>()},
         {"x-kmime-rfc2231", std::make_unique<KCodecs::Rfc2231EncodingCodec>()},
         {"x-uuencode", std::make_unique<KCodecs::UUCodec>()},
     }};
 
     const auto it = std::lower_bound(s_codecs.begin(), s_codecs.end(), name, [](const auto &lhs, auto rhs) {
         return rhs.compare(lhs.name, Qt::CaseInsensitive) > 0;
     });
     if (it == s_codecs.end() || name.compare((*it).name, Qt::CaseInsensitive) != 0) {
         qWarning() << "Unknown codec \"" << name << "\" requested!";
     }
     return (*it).codec.get();
 }
 
 bool KCodecs::Codec::encode(const char *&scursor, const char *const send, char *&dcursor, const char *const dend, NewlineType newline) const
 {
     // get an encoder:
     std::unique_ptr<Encoder> enc(makeEncoder(newline));
     if (!enc) {
         qWarning() << "makeEncoder failed for" << name();
         return false;
     }
 
     // encode and check for output buffer overflow:
     while (!enc->encode(scursor, send, dcursor, dend)) {
         if (dcursor == dend) {
             return false; // not enough space in output buffer
         }
     }
 
     // finish and check for output buffer overflow:
     while (!enc->finish(dcursor, dend)) {
         if (dcursor == dend) {
             return false; // not enough space in output buffer
         }
     }
 
     return true; // successfully encoded.
 }
 
 QByteArray KCodecs::Codec::encode(QByteArrayView src, NewlineType newline) const
 {
     // allocate buffer for the worst case:
     QByteArray result;
     result.resize(maxEncodedSizeFor(src.size(), newline));
 
     // set up iterators:
     QByteArray::ConstIterator iit = src.begin();
     QByteArray::ConstIterator iend = src.end();
     QByteArray::Iterator oit = result.begin();
     QByteArray::ConstIterator oend = result.end();
 
     // encode
     if (!encode(iit, iend, oit, oend, newline)) {
         qCritical() << name() << "codec lies about it's mEncodedSizeFor()";
     }
 
     // shrink result to actual size:
     result.truncate(oit - result.begin());
 
     return result;
 }
 
 QByteArray KCodecs::Codec::decode(QByteArrayView src, NewlineType newline) const
 {
     // allocate buffer for the worst case:
     QByteArray result;
     result.resize(maxDecodedSizeFor(src.size(), newline));
 
     // set up iterators:
     QByteArray::ConstIterator iit = src.begin();
     QByteArray::ConstIterator iend = src.end();
     QByteArray::Iterator oit = result.begin();
     QByteArray::ConstIterator oend = result.end();
 
     // decode
     if (!decode(iit, iend, oit, oend, newline)) {
         qCritical() << name() << "codec lies about it's maxDecodedSizeFor()";
     }
 
     // shrink result to actual size:
     result.truncate(oit - result.begin());
 
     return result;
 }
 
 bool KCodecs::Codec::decode(const char *&scursor, const char *const send, char *&dcursor, const char *const dend, NewlineType newline) const
 {
     // get a decoder:
     std::unique_ptr<Decoder> dec(makeDecoder(newline));
     assert(dec);
 
     // decode and check for output buffer overflow:
     while (!dec->decode(scursor, send, dcursor, dend)) {
         if (dcursor == dend) {
             return false; // not enough space in output buffer
         }
     }
 
     // finish and check for output buffer overflow:
     while (!dec->finish(dcursor, dend)) {
         if (dcursor == dend) {
             return false; // not enough space in output buffer
         }
     }
 
     return true; // successfully encoded.
 }
 
 /******************************************************************************/
 /*                          KCodecs::Encoder                                  */
 
 KCodecs::EncoderPrivate::EncoderPrivate(Codec::NewlineType newline)
     : outputBufferCursor(0)
     , newline(newline)
 {
 }
 
 KCodecs::Encoder::Encoder(Codec::NewlineType newline)
     : d(new KCodecs::EncoderPrivate(newline))
 {
 }
 
 KCodecs::Encoder::~Encoder() = default;
 
 bool KCodecs::Encoder::write(char ch, char *&dcursor, const char *const dend)
 {
     if (dcursor != dend) {
         // if there's space in the output stream, write there:
         *dcursor++ = ch;
         return true;
     } else {
         // else buffer the output:
         if (d->outputBufferCursor >= maxBufferedChars) {
             qCritical() << "KCodecs::Encoder: internal buffer overflow!";
         } else {
             d->outputBuffer[d->outputBufferCursor++] = ch;
         }
         return false;
     }
 }
 
 // write as much as possible off the output buffer. Return true if
 // flushing was complete, false if some chars could not be flushed.
 bool KCodecs::Encoder::flushOutputBuffer(char *&dcursor, const char *const dend)
 {
     int i;
     // copy output buffer to output stream:
     for (i = 0; dcursor != dend && i < d->outputBufferCursor; ++i) {
         *dcursor++ = d->outputBuffer[i];
     }
 
     // calculate the number of missing chars:
     int numCharsLeft = d->outputBufferCursor - i;
     // push the remaining chars to the beginning of the buffer:
     if (numCharsLeft) {
         ::memmove(d->outputBuffer, d->outputBuffer + i, numCharsLeft);
     }
     // adjust cursor:
     d->outputBufferCursor = numCharsLeft;
 
     return !numCharsLeft;
 }
 
 bool KCodecs::Encoder::writeCRLF(char *&dcursor, const char *const dend)
 {
     if (d->newline == Codec::NewlineCRLF) {
         write('\r', dcursor, dend);
     }
     return write('\n', dcursor, dend);
 }
 
 /******************************************************************************/
 /*                           KCodecs::Decoder                                 */
 
 KCodecs::DecoderPrivate::DecoderPrivate(Codec::NewlineType newline)
     : newline(newline)
 {
 }
 
 KCodecs::Decoder::Decoder(Codec::NewlineType newline)
     : d(new KCodecs::DecoderPrivate(newline))
 {
 }
 
 KCodecs::Decoder::~Decoder() = default;