File indexing completed on 2024-12-22 05:05:20

 // This file is part of KMail, the KDE mail client.
 // SPDX-FileCopyrightText: 2003      Marc Mutz <mutz@kde.org>
 // SPDX-FileCopyrightText: 2002-2004 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.net
 // SPDX-FileCopyrightText: 2009 Andras Mantia <andras@kdab.net>
 // SPDX-FileCopyrightText: 2015 Sandro Knauß <sknauss@kde.org>
 // SPDX-FileCopyrightText: 2017 Christian Mollekopf <mollekopf@kolabsystems.com>
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "objecttreeparser.h"
 
 #include "bodypartformatterbasefactory.h"
 
 #include "bodypartformatter.h"
 
 #include <KMime/Message>
 
 #include <KCharsets>
 #include <QByteArray>
 #include <QDebug>
 #include <QMimeDatabase>
 #include <QRegularExpression>
 #include <QStringDecoder>
 #include <QTextStream>
 #include <QUrl>
 
 using namespace MimeTreeParser;
 
 /*
  * Collect message parts bottom up.
  * Filter to avoid evaluating a subtree.
  * Select parts to include it in the result set. Selecting a part in a branch will keep any parent parts from being selected.
  */
 static QList<MessagePart::Ptr> collect(MessagePart::Ptr start,
                                        const std::function<bool(const MessagePart::Ptr &)> &evaluateSubtree,
                                        const std::function<bool(const MessagePart::Ptr &)> &select)
 {
     auto ptr = start.dynamicCast<MessagePart>();
     Q_ASSERT(ptr);
     MessagePart::List list;
     if (evaluateSubtree(ptr)) {
         for (const auto &p : ptr->subParts()) {
             list << ::collect(p, evaluateSubtree, select);
         }
     }
 
     // Don't consider this part if we already selected a subpart
     if (list.isEmpty()) {
         if (select(ptr)) {
             list << start;
         }
     }
     return list;
 }
 
 QString ObjectTreeParser::plainTextContent()
 {
     QString content;
     if (mParsedPart) {
         auto plainParts = ::collect(
             mParsedPart,
             [](const MessagePart::Ptr &) {
                 return true;
             },
             [](const MessagePart::Ptr &part) {
                 if (part->isAttachment()) {
                     return false;
                 }
                 if (dynamic_cast<MimeTreeParser::TextMessagePart *>(part.data())) {
                     return true;
                 }
                 if (dynamic_cast<MimeTreeParser::AlternativeMessagePart *>(part.data())) {
                     return true;
                 }
                 return false;
             });
         for (const auto &part : plainParts) {
             content += part->text();
         }
     }
     return content;
 }
 
 QString ObjectTreeParser::htmlContent()
 {
     QString content;
     if (mParsedPart) {
         MessagePart::List contentParts = ::collect(
             mParsedPart,
             [](const MessagePart::Ptr &) {
                 return true;
             },
             [](const MessagePart::Ptr &part) {
                 if (dynamic_cast<MimeTreeParser::HtmlMessagePart *>(part.data())) {
                     return true;
                 }
                 if (dynamic_cast<MimeTreeParser::AlternativeMessagePart *>(part.data())) {
                     return true;
                 }
                 return false;
             });
         for (const auto &part : contentParts) {
             if (auto p = dynamic_cast<MimeTreeParser::AlternativeMessagePart *>(part.data())) {
                 content += p->htmlContent();
             } else {
                 content += part->text();
             }
         }
     }
     return content;
 }
 
 bool ObjectTreeParser::hasEncryptedParts() const
 {
     bool result = false;
 
     ::collect(
         mParsedPart,
         [](const MessagePart::Ptr &) {
             return true;
         },
         [&result](const MessagePart::Ptr &part) {
             if (const auto enc = dynamic_cast<MimeTreeParser::EncryptedMessagePart *>(part.data())) {
                 result = true;
             }
             return false;
         });
 
     return result;
 }
 
 bool ObjectTreeParser::hasSignedParts() const
 {
     bool result = false;
 
     ::collect(
         mParsedPart,
         [](const MessagePart::Ptr &) {
             return true;
         },
         [&result](const MessagePart::Ptr &part) {
             if (const auto enc = dynamic_cast<MimeTreeParser::SignedMessagePart *>(part.data())) {
                 result = true;
             }
             return false;
         });
 
     return result;
 }
 
 static void print(QTextStream &stream, KMime::Content *node, const QString prefix = {})
 {
     QByteArray mediaType("text");
     QByteArray subType("plain");
     if (node->contentType(false) && !node->contentType()->mediaType().isEmpty() && !node->contentType()->subType().isEmpty()) {
         mediaType = node->contentType()->mediaType();
         subType = node->contentType()->subType();
     }
     stream << prefix << "! " << mediaType << subType << " isAttachment: " << KMime::isAttachment(node) << "\n";
     const auto contents = node->contents();
     for (const auto nodeContent : contents) {
         print(stream, nodeContent, prefix + QLatin1StringView(" "));
     }
 }
 
 static void print(QTextStream &stream, const MessagePart &messagePart, const QByteArray pre = {})
 {
     stream << pre << "# " << messagePart.metaObject()->className() << " isAttachment: " << messagePart.isAttachment() << "\n";
     const auto subParts = messagePart.subParts();
     for (const auto &subPart : subParts) {
         print(stream, *subPart, pre + " ");
     }
 }
 
 QString ObjectTreeParser::structureAsString() const
 {
     QString string;
     QTextStream stream{&string};
 
     if (mTopLevelContent) {
         ::print(stream, mTopLevelContent);
     }
     if (mParsedPart) {
         ::print(stream, *mParsedPart);
     }
     return string;
 }
 
 void ObjectTreeParser::print()
 {
     qInfo().noquote() << structureAsString();
 }
 
 static KMime::Content *find(KMime::Content *node, const std::function<bool(KMime::Content *)> &select)
 {
     QByteArray mediaType("text");
     QByteArray subType("plain");
     if (node->contentType(false) && !node->contentType()->mediaType().isEmpty() && !node->contentType()->subType().isEmpty()) {
         mediaType = node->contentType()->mediaType();
         subType = node->contentType()->subType();
     }
     if (select(node)) {
         return node;
     }
     const auto contents = node->contents();
     for (const auto nodeContent : contents) {
         if (const auto content = find(nodeContent, select)) {
             return content;
         }
     }
     return nullptr;
 }
 
 KMime::Content *ObjectTreeParser::find(const std::function<bool(KMime::Content *)> &select)
 {
     return ::find(mTopLevelContent, select);
 }
 
 MessagePart::List ObjectTreeParser::collectContentParts()
 {
     return collectContentParts(mParsedPart);
 }
 
 MessagePart::List ObjectTreeParser::collectContentParts(MessagePart::Ptr start)
 {
     return ::collect(
         start,
         [start](const MessagePart::Ptr &part) {
             // Ignore the top-level
             if (start.data() == part.data()) {
                 return true;
             }
             if (auto encapsulatedPart = part.dynamicCast<MimeTreeParser::EncapsulatedRfc822MessagePart>()) {
                 return false;
             }
             return true;
         },
         [start](const MessagePart::Ptr &part) {
             if (const auto attachment = dynamic_cast<MimeTreeParser::AttachmentMessagePart *>(part.data())) {
                 return attachment->mimeType() == "text/calendar";
             } else if (const auto text = dynamic_cast<MimeTreeParser::TextMessagePart *>(part.data())) {
                 auto enc = dynamic_cast<MimeTreeParser::EncryptedMessagePart *>(text->parentPart());
                 if (enc && enc->error()) {
                     return false;
                 }
 
                 return true;
             } else if (dynamic_cast<MimeTreeParser::AlternativeMessagePart *>(part.data())) {
                 return true;
             } else if (dynamic_cast<MimeTreeParser::HtmlMessagePart *>(part.data())) {
                 // Don't if we have an alternative part as parent
                 return true;
             } else if (dynamic_cast<MimeTreeParser::EncapsulatedRfc822MessagePart *>(part.data())) {
                 if (start.data() == part.data()) {
                     return false;
                 }
                 return true;
             } else if (const auto enc = dynamic_cast<MimeTreeParser::EncryptedMessagePart *>(part.data())) {
                 if (enc->error()) {
                     return true;
                 }
                 // If we have a textpart with encrypted and unencrypted subparts we want to return the textpart
                 if (dynamic_cast<MimeTreeParser::TextMessagePart *>(enc->parentPart())) {
                     return false;
                 }
             } else if (const auto sig = dynamic_cast<MimeTreeParser::SignedMessagePart *>(part.data())) {
                 // Signatures without subparts already contain the text
                 return !sig->hasSubParts();
             }
             return false;
         });
 }
 
 MessagePart::List ObjectTreeParser::collectAttachmentParts()
 {
     MessagePart::List contentParts = ::collect(
         mParsedPart,
         [](const MessagePart::Ptr &) {
             return true;
         },
         [](const MessagePart::Ptr &part) {
             return part->isAttachment();
         });
     return contentParts;
 }
 
 /*
  * This naive implementation assumes that there is an encrypted part wrapping a signature.
  * For other cases we would have to process both recursively (I think?)
  */
 void ObjectTreeParser::decryptAndVerify()
 {
     // We first decrypt
     ::collect(
         mParsedPart,
         [](const MessagePart::Ptr &) {
             return true;
         },
         [](const MessagePart::Ptr &part) {
             if (const auto enc = dynamic_cast<MimeTreeParser::EncryptedMessagePart *>(part.data())) {
                 enc->startDecryption();
             }
             return false;
         });
     // And then verify the available signatures
     ::collect(
         mParsedPart,
         [](const MessagePart::Ptr &) {
             return true;
         },
         [](const MessagePart::Ptr &part) {
             if (const auto enc = dynamic_cast<MimeTreeParser::SignedMessagePart *>(part.data())) {
                 enc->startVerification();
             }
             return false;
         });
 }
 
 QString ObjectTreeParser::resolveCidLinks(const QString &html)
 {
     auto text = html;
     static const auto regex = QRegularExpression(QLatin1StringView("(src)\\s*=\\s*(\"|')(cid:[^\"']+)\\2"));
     auto it = regex.globalMatch(text);
     while (it.hasNext()) {
         const auto match = it.next();
         const auto link = QUrl(match.captured(3));
         auto cid = link.path();
         auto mailMime = const_cast<KMime::Content *>(find([=](KMime::Content *content) {
             if (!content || !content->contentID(false)) {
                 return false;
             }
             return QString::fromLatin1(content->contentID(false)->identifier()) == cid;
         }));
         if (mailMime) {
             const auto contentType = mailMime->contentType(false);
             if (!contentType) {
                 qWarning() << "No content type, skipping";
                 continue;
             }
             QMimeDatabase mimeDb;
             const auto mimetype = mimeDb.mimeTypeForName(QString::fromLatin1(contentType->mimeType())).name();
             if (mimetype.startsWith(QLatin1StringView("image/"))) {
                 // We reencode to base64 below.
                 const auto data = mailMime->decodedContent();
                 if (data.isEmpty()) {
                     qWarning() << "Attachment is empty.";
                     continue;
                 }
                 text.replace(match.captured(0), QString::fromLatin1("src=\"data:%1;base64,%2\"").arg(mimetype, QString::fromLatin1(data.toBase64())));
             }
         } else {
             qWarning() << "Failed to find referenced attachment: " << cid;
         }
     }
     return text;
 }
 
 //-----------------------------------------------------------------------------
 
 void ObjectTreeParser::parseObjectTree(const QByteArray &mimeMessage)
 {
     const auto mailData = KMime::CRLFtoLF(mimeMessage);
     mMsg = KMime::Message::Ptr(new KMime::Message);
     mMsg->setContent(mailData);
     mMsg->parse();
     // We avoid using mMsg->contentType()->charset(), because that will just return kmime's defaultCharset(), ISO-8859-1
     const auto charset = mMsg->contentType()->parameter(QStringLiteral("charset")).toLatin1();
     if (charset.isEmpty()) {
         mMsg->contentType()->setCharset("us-ascii");
     }
     parseObjectTree(mMsg.data());
 }
 
 void ObjectTreeParser::parseObjectTree(KMime::Content *node)
 {
     mTopLevelContent = node;
     mParsedPart = parseObjectTreeInternal(node, false);
 }
 
 MessagePart::Ptr ObjectTreeParser::parsedPart() const
 {
     return mParsedPart;
 }
 
 /*
  * This will lookup suitable formatters based on the type,
  * and let them generate a list of parts.
  * If the formatter generated a list of parts, then those are taken, otherwise we move on to the next match.
  */
 MessagePart::List ObjectTreeParser::processType(KMime::Content *node, const QByteArray &mediaType, const QByteArray &subType)
 {
     static MimeTreeParser::BodyPartFormatterBaseFactory factory;
     const auto sub = factory.subtypeRegistry(mediaType.constData());
     const auto range = sub.equal_range(subType.constData());
     for (auto it = range.first; it != range.second; ++it) {
         const auto formatter = it->second;
         if (!formatter) {
             continue;
         }
         const auto list = formatter->processList(this, node);
         if (!list.isEmpty()) {
             return list;
         }
     }
     return {};
 }
 
 MessagePart::Ptr ObjectTreeParser::parseObjectTreeInternal(KMime::Content *node, bool onlyOneMimePart)
 {
     if (!node) {
         return MessagePart::Ptr();
     }
 
     auto parsedPart = MessagePart::Ptr(new MessagePartList(this, node));
     parsedPart->setIsRoot(node->isTopLevel());
     const auto contents = node->parent() ? node->parent()->contents() : KMime::Content::List{node};
     for (int i = contents.indexOf(node); i < contents.size(); ++i) {
         node = contents.at(i);
 
         QByteArray mediaType("text");
         QByteArray subType("plain");
         if (node->contentType(false) && !node->contentType()->mediaType().isEmpty() && !node->contentType()->subType().isEmpty()) {
             mediaType = node->contentType()->mediaType();
             subType = node->contentType()->subType();
         }
 
         auto messageParts = [&] {
             // Try the specific type handler
             {
                 auto list = processType(node, mediaType, subType);
                 if (!list.isEmpty()) {
                     return list;
                 }
             }
             // Fallback to the generic handler
             {
                 auto list = processType(node, mediaType, "*");
                 if (!list.isEmpty()) {
                     return list;
                 }
             }
             // Fallback to the default handler
             return defaultHandling(node);
         }();
 
         for (const auto &part : messageParts) {
             parsedPart->appendSubPart(part);
         }
 
         if (onlyOneMimePart) {
             break;
         }
     }
 
     return parsedPart;
 }
 
 QList<MessagePart::Ptr> ObjectTreeParser::defaultHandling(KMime::Content *node)
 {
     if (node->contentType()->mimeType() == QByteArrayLiteral("application/octet-stream")
         && (node->contentType()->name().endsWith(QLatin1StringView("p7m")) || node->contentType()->name().endsWith(QLatin1StringView("p7s"))
             || node->contentType()->name().endsWith(QLatin1StringView("p7c")))) {
         auto list = processType(node, "application", "pkcs7-mime");
         if (!list.isEmpty()) {
             return list;
         }
     }
 
     return {AttachmentMessagePart::Ptr(new AttachmentMessagePart(this, node))};
 }
 
 QByteArray ObjectTreeParser::codecNameFor(KMime::Content *node) const
 {
     if (!node) {
         return QByteArrayLiteral("UTF-8");
     }
 
     QByteArray charset = node->contentType()->charset().toLower();
 
     // utf-8 is a superset of us-ascii, so we don't lose anything if we use it instead
     // utf-8 is used so widely nowadays that it is a good idea to use it to fix issues with broken clients.
     if (charset == "us-ascii") {
         charset = "utf-8";
     }
     if (!charset.isEmpty()) {
         if (const QStringDecoder c(charset.constData()); c.isValid()) {
             return charset;
         }
     }
     // no charset means us-ascii (RFC 2045), so using local encoding should
     // be okay
     return QByteArrayLiteral("UTF-8");
 }