Refactor the code handling emoji

- Use a dedicated structure, EmojiEntry, instead of QVariantMap
  (it's Q_GADGET, should be readable from QML just fine)
- While we're at it, QVector is better than QList in Qt 5.15
- Remove language from the session state - it's used in a single method
- Modernise handleKey() code

2 files changed, 91 insertions, 56 deletions

diff --git a/lib/keyverificationsession.cpp b/lib/keyverificationsession.cpp
index caf5071a..2c468c3e 100644
--- a/lib/keyverificationsession.cpp
+++ b/lib/keyverificationsession.cpp
@@ -110,9 +110,6 @@ void KeyVerificationSession::init(milliseconds timeout)
     auto randomSize = olm_create_sas_random_length(m_sas);
     auto random = getRandom(randomSize);
     olm_create_sas(m_sas, random.data(), randomSize);
-
-    m_language = QLocale::system().uiLanguages()[0];
-    m_language = m_language.left(m_language.indexOf('-'));
 }
 
 KeyVerificationSession::~KeyVerificationSession()
@@ -121,18 +118,57 @@ KeyVerificationSession::~KeyVerificationSession()
     delete[] reinterpret_cast<std::byte*>(m_sas);
 }
 
+struct EmojiStoreEntry : EmojiEntry {
+    QHash<QString, QString> translatedDescriptions;
+
+    explicit EmojiStoreEntry(const QJsonObject& json)
+        : EmojiEntry{ fromJson<QString>(json["emoji"]),
+                      fromJson<QString>(json["description"]) }
+        , translatedDescriptions{ fromJson<QHash<QString, QString>>(
+              json["translated_descriptions"]) }
+    {}
+};
+
+using EmojiStore = QVector<EmojiStoreEntry>;
+
+EmojiStore loadEmojiStore()
+{
+    QFile dataFile(":/sas-emoji.json");
+    dataFile.open(QFile::ReadOnly);
+    return fromJson<EmojiStore>(
+        QJsonDocument::fromJson(dataFile.readAll()).array());
+}
+
+EmojiEntry emojiForCode(int code, const QString& language)
+{
+    static const EmojiStore emojiStore = loadEmojiStore();
+    const auto& entry = emojiStore[code];
+    if (!language.isEmpty())
+        if (const auto translatedDescription =
+            emojiStore[code].translatedDescriptions.value(language);
+            !translatedDescription.isNull())
+            return { entry.emoji, translatedDescription };
+
+    return SLICE(entry, EmojiEntry);
+}
+
 void KeyVerificationSession::handleKey(const KeyVerificationKeyEvent& event)
 {
     if (state() != WAITINGFORKEY && state() != WAITINGFORVERIFICATION) {
         cancelVerification(UNEXPECTED_MESSAGE);
         return;
     }
-    olm_sas_set_their_key(m_sas, event.key().toLatin1().data(), event.key().toLatin1().size());
+    auto eventKey = event.key().toLatin1();
+    olm_sas_set_their_key(m_sas, eventKey.data(), eventKey.size());
 
     if (startSentByUs) {
-        auto commitment = QString(QCryptographicHash::hash((event.key() % m_startEvent).toLatin1(), QCryptographicHash::Sha256).toBase64());
-        commitment = commitment.left(commitment.indexOf('='));
-        if (commitment != m_commitment) {
+        const auto paddedCommitment =
+            QCryptographicHash::hash((eventKey % m_startEvent).toLatin1(),
+                                     QCryptographicHash::Sha256)
+                .toBase64();
+        const QLatin1String unpaddedCommitment(paddedCommitment.constData(),
+                                               paddedCommitment.indexOf('='));
+        if (unpaddedCommitment != m_commitment) {
             qCWarning(E2EE) << "Commitment mismatch; aborting verification";
             cancelVerification(MISMATCHED_COMMITMENT);
             return;
@@ -142,34 +178,40 @@ void KeyVerificationSession::handleKey(const KeyVerificationKeyEvent& event)
     }
     setState(WAITINGFORVERIFICATION);
 
-    QByteArray keyBytes(olm_sas_pubkey_length(m_sas), '\0');
-    olm_sas_get_pubkey(m_sas, keyBytes.data(), keyBytes.size());
-    QString key = QString(keyBytes);
-
-    QByteArray output(6, '\0');
-    QString infoTemplate = startSentByUs ? "MATRIX_KEY_VERIFICATION_SAS|%1|%2|%3|%4|%5|%6|%7"_ls : "MATRIX_KEY_VERIFICATION_SAS|%4|%5|%6|%1|%2|%3|%7"_ls;
-
-    auto info = infoTemplate.arg(m_connection->userId()).arg(m_connection->deviceId()).arg(key).arg(m_remoteUserId).arg(m_remoteDeviceId).arg(event.key()).arg(m_transactionId);
-    olm_sas_generate_bytes(m_sas, info.toLatin1().data(), info.toLatin1().size(), output.data(), output.size());
-
-    QVector<uint8_t> code(7, 0);
-    const auto& data = (uint8_t *) output.data();
-
-    code[0] = data[0] >> 2;
-    code[1] = (data[0] << 4 & 0x3f) | data[1] >> 4;
-    code[2] = (data[1] << 2 & 0x3f) | data[2] >> 6;
-    code[3] = data[2] & 0x3f;
-    code[4] = data[3] >> 2;
-    code[5] = (data[3] << 4 & 0x3f) | data[4] >> 4;
-    code[6] = (data[4] << 2 & 0x3f) | data[5] >> 6;
-
-    for (const auto& c : code) {
-        auto [emoji, description] = emojiForCode(c);
-        QVariantMap map;
-        map["emoji"] = emoji;
-        map["description"] = description;
-        m_sasEmojis += map;
-    }
+    std::string key(olm_sas_pubkey_length(m_sas), '\0');
+    olm_sas_get_pubkey(m_sas, key.data(), key.size());
+
+    std::array<std::byte, 6> output{};
+    const auto infoTemplate =
+        startSentByUs ? "MATRIX_KEY_VERIFICATION_SAS|%1|%2|%3|%4|%5|%6|%7"_ls
+                      : "MATRIX_KEY_VERIFICATION_SAS|%4|%5|%6|%1|%2|%3|%7"_ls;
+
+    const auto info = infoTemplate
+                          .arg(m_connection->userId(), m_connection->deviceId(),
+                               key.data(), m_remoteUserId, m_remoteDeviceId,
+                               eventKey, m_transactionId)
+                          .toLatin1();
+    olm_sas_generate_bytes(m_sas, info.data(), info.size(), output.data(),
+                           output.size());
+
+    static constexpr auto x3f = std::byte{ 0x3f };
+    const std::array<std::byte, 7> code{
+        output[0] >> 2,
+        (output[0] << 4 & x3f) | output[1] >> 4,
+        (output[1] << 2 & x3f) | output[2] >> 6,
+        output[2] & x3f,
+        output[3] >> 2,
+        (output[3] << 4 & x3f) | output[4] >> 4,
+        (output[4] << 2 & x3f) | output[5] >> 6
+    };
+
+    const auto uiLanguages = QLocale().uiLanguages();
+    const auto preferredLanguage = uiLanguages.isEmpty()
+                                       ? QString()
+                                       : uiLanguages.front().section('-', 0, 0);
+    for (const auto& c : code)
+        m_sasEmojis += emojiForCode(std::to_integer<int>(c), preferredLanguage);
+
     emit sasEmojisChanged();
     emit keyReceived();
 }
@@ -369,21 +411,7 @@ void KeyVerificationSession::handleCancel(const KeyVerificationCancelEvent& even
     setState(CANCELED);
 }
 
-std::pair<QString, QString> KeyVerificationSession::emojiForCode(int code)
-{
-    static QJsonArray data;
-    if (data.isEmpty()) {
-        QFile dataFile(":/sas-emoji.json");
-        dataFile.open(QFile::ReadOnly);
-        data = QJsonDocument::fromJson(dataFile.readAll()).array();
-    }
-    if (data[code].toObject()["translated_descriptions"].toObject().contains(m_language)) {
-        return {data[code].toObject()["emoji"].toString(), data[code].toObject()["translated_descriptions"].toObject()[m_language].toString()};
-    }
-    return {data[code].toObject()["emoji"].toString(), data[code].toObject()["description"].toString()};
-}
-
-QList<QVariantMap> KeyVerificationSession::sasEmojis() const
+QVector<EmojiEntry> KeyVerificationSession::sasEmojis() const
 {
     return m_sasEmojis;
 }
diff --git a/lib/keyverificationsession.h b/lib/keyverificationsession.h
index 73c9384e..aa0295cb 100644
--- a/lib/keyverificationsession.h
+++ b/lib/keyverificationsession.h
@@ -12,6 +12,15 @@ struct OlmSAS;
 namespace Quotient {
 class Connection;
 
+struct QUOTIENT_API EmojiEntry {
+    QString emoji;
+    QString description;
+
+    Q_GADGET
+    Q_PROPERTY(QString emoji MEMBER emoji CONSTANT)
+    Q_PROPERTY(QString description MEMBER description CONSTANT)
+};
+
 /** A key verification session. Listen for incoming sessions by connecting to Connection::newKeyVerificationSession.
     Start a new session using Connection::startKeyVerificationSession.
     The object is delete after finished is emitted.
@@ -67,7 +76,7 @@ public:
     Q_ENUM(Error)
 
     Q_PROPERTY(QString remoteDeviceId MEMBER m_remoteDeviceId CONSTANT)
-    Q_PROPERTY(QList<QVariantMap> sasEmojis READ sasEmojis NOTIFY sasEmojisChanged)
+    Q_PROPERTY(QVector<EmojiEntry> sasEmojis READ sasEmojis NOTIFY sasEmojisChanged)
     Q_PROPERTY(State state READ state NOTIFY stateChanged)
     Q_PROPERTY(Error error READ error NOTIFY errorChanged)
 
@@ -79,7 +88,7 @@ public:
     ~KeyVerificationSession() override;
     Q_DISABLE_COPY_MOVE(KeyVerificationSession)
 
-    QList<QVariantMap> sasEmojis() const;
+    QVector<EmojiEntry> sasEmojis() const;
     State state() const;
 
     Error error() const;
@@ -107,13 +116,12 @@ private:
     const QString m_transactionId;
     Connection* m_connection;
     OlmSAS* m_sas = nullptr;
-    QList<QVariantMap> m_sasEmojis;
+    QVector<EmojiEntry> m_sasEmojis;
     bool startSentByUs = false;
     State m_state = INCOMING;
     Error m_error = NONE;
     QString m_startEvent;
     QString m_commitment;
-    QString m_language;
     bool macReceived = false;
     bool m_encrypted;
     QStringList m_remoteSupportedMethods;
@@ -133,8 +141,7 @@ private:
 
     QByteArray macInfo(bool verifying, const QString& key = "KEY_IDS"_ls);
     QString calculateMac(const QString& input, bool verifying, const QString& keyId= "KEY_IDS"_ls);
-
-    std::pair<QString, QString> emojiForCode(int code);
 };
 
 } // namespace Quotient
+Q_DECLARE_METATYPE(Quotient::EmojiEntry)