applicationpkcs7mime.cpp

/*
   SPDX-FileCopyrightText: 2016 Sandro Knauß <sknauss@kde.org>
 
   SPDX-License-Identifier: LGPL-2.0-or-later
*/
 
#include "applicationpkcs7mime.h"
 
#include "messagepart.h"
#include "objecttreeparser.h"
 
#include <QGpgME/Protocol>
 
#include <KMime/Content>
 
#include "mimetreeparser_debug.h"
 
using namespace MimeTreeParser;
 
const ApplicationPkcs7MimeBodyPartFormatter *ApplicationPkcs7MimeBodyPartFormatter::self;
 
const Interface::BodyPartFormatter *ApplicationPkcs7MimeBodyPartFormatter::create()
{
    if (!self) {
        self = new ApplicationPkcs7MimeBodyPartFormatter();
    }
    return self;
}
 
MessagePart::Ptr ApplicationPkcs7MimeBodyPartFormatter::process(Interface::BodyPart &part) const
{
    KMime::Content *node = part.content();
 
    if (node->head().isEmpty()) {
        return {};
    }
 
    const auto smimeCrypto = QGpgME::smime();
    if (!smimeCrypto) {
        return {};
    }
 
    // we are also registered for octet-stream, in that case stop here if that's not a part for us
    const auto ct = node->contentType(); // Create
    const auto mt = ct->mimeType();
    const auto isCorrectMimeType = mt == QByteArrayLiteral("application/pkcs7-mime") || mt == QByteArrayLiteral("application/x-pkcs7-mime");
    const auto hasCorrectName = mt == QByteArrayLiteral("application/octet-stream")
        && (ct->name().endsWith(QLatin1StringView("p7m")) || ct->name().endsWith(QLatin1StringView("p7s")) || ct->name().endsWith(QLatin1StringView("p7c")));
    if (!isCorrectMimeType && !hasCorrectName) {
        return {};
    }
 
    const QString smimeType = node->contentType(false)->parameter("smime-type").toLower();
 
    if (smimeType == QLatin1StringView("certs-only")) {
        part.processResult()->setNeverDisplayInline(true);
 
        CertMessagePart::Ptr mp(new CertMessagePart(part.objectTreeParser(), node, smimeCrypto, part.source()->autoImportKeys()));
        return mp;
    }
 
    bool isSigned = (smimeType == QLatin1StringView("signed-data"));
    bool isEncrypted = (smimeType == QLatin1StringView("enveloped-data"));
 
    // Analyze "signTestNode" node to find/verify a signature.
    // If zero part.objectTreeParser() verification was successfully done after
    // decrypting via recursion by insertAndParseNewChildNode().
    KMime::Content *signTestNode = isEncrypted ? nullptr : node;
 
    // We try decrypting the content
    // if we either *know* that it is an encrypted message part
    // or there is neither signed nor encrypted parameter.
    MessagePart::Ptr mp;
    if (!isSigned) {
        if (isEncrypted) {
            qCDebug(MIMETREEPARSER_LOG) << "pkcs7 mime     ==      S/MIME TYPE: enveloped (encrypted) data";
        } else {
            qCDebug(MIMETREEPARSER_LOG) << "pkcs7 mime  -  type unknown  -  enveloped (encrypted) data ?";
        }
 
        auto _mp = EncryptedMessagePart::Ptr(
            new EncryptedMessagePart(part.objectTreeParser(), node->decodedText(), smimeCrypto, part.nodeHelper()->fromAsString(node), node));
        mp = _mp;
        _mp->setIsEncrypted(true);
        _mp->setDecryptMessage(part.source()->decryptMessage());
        PartMetaData *messagePart(_mp->partMetaData());
        if (!part.source()->decryptMessage()) {
            isEncrypted = true;
            signTestNode = nullptr; // PENDING(marc) to be abs. sure, we'd need to have to look at the content
        } else {
            _mp->startDecryption();
            if (messagePart->isDecryptable) {
                qCDebug(MIMETREEPARSER_LOG) << "pkcs7 mime  -  encryption found  -  enveloped (encrypted) data !";
                isEncrypted = true;
                part.nodeHelper()->setEncryptionState(node, KMMsgFullyEncrypted);
                signTestNode = nullptr;
            } else {
                // decryption failed, which could be because the part was encrypted but
                // decryption failed, or because we didn't know if it was encrypted, tried,
                // and failed. If the message was not actually encrypted, we continue
                // assuming it's signed
                if (_mp->passphraseError() || (smimeType.isEmpty() && messagePart->isEncrypted)) {
                    isEncrypted = true;
                    signTestNode = nullptr;
                }
 
                if (isEncrypted) {
                    qCDebug(MIMETREEPARSER_LOG) << "pkcs7 mime  -  ERROR: COULD NOT DECRYPT enveloped data !";
                } else {
                    qCDebug(MIMETREEPARSER_LOG) << "pkcs7 mime  -  NO encryption found";
                }
            }
        }
 
        if (isEncrypted) {
            part.nodeHelper()->setEncryptionState(node, KMMsgFullyEncrypted);
        }
    }
 
    // We now try signature verification if necessary.
    if (signTestNode) {
        if (isSigned) {
            qCDebug(MIMETREEPARSER_LOG) << "pkcs7 mime     ==      S/MIME TYPE: opaque signed data";
        } else {
            qCDebug(MIMETREEPARSER_LOG) << "pkcs7 mime  -  type unknown  -  opaque signed data ?";
        }
 
        QStringDecoder aCodec(part.objectTreeParser()->codecNameFor(signTestNode).constData());
        const QByteArray signaturetext = signTestNode->decodedContent();
        auto _mp = SignedMessagePart::Ptr(
            new SignedMessagePart(part.objectTreeParser(), aCodec.decode(signaturetext), smimeCrypto, part.nodeHelper()->fromAsString(node), signTestNode));
        mp = _mp;
        _mp->startVerificationDetached(signaturetext, nullptr, QByteArray());
 
        if (_mp->isSigned()) {
            if (!isSigned) {
                qCDebug(MIMETREEPARSER_LOG) << "pkcs7 mime  -  signature found  -  opaque signed data !";
            }
 
            if (signTestNode != node) {
                part.nodeHelper()->setSignatureState(node, KMMsgFullySigned);
            }
        } else {
            qCDebug(MIMETREEPARSER_LOG) << "pkcs7 mime  -  NO signature found   :-(";
        }
    }
 
    return mp;
}