RemoteID: validate EU operator ID (mavlink#10970)

This implements the validation of the operator ID as required for the EU remote ID spec.

The way it works is that:

1. The user enters the operator ID including the checksum and secret.
2. The ID is validated using the secret against the checksum.
3. The secret is removed and the public ID is saved, as well as a flag signalling that the ID has been checked.

This work is sponsored by bluemark.io., https://github.com/BluemarkInnovations.

Signed-off-by: Julian Oes <julian@oes.ch>

src/Settings/RemoteID.SettingsGroup.json

@@ -16,6 +16,13 @@
     "type":         "string",
     "default":      ""
 },
+{
+    "name":         "operatorIDValid",
+    "shortDesc":    "Operator ID is valid",
+    "longDesc":     "Operator ID has been checked using checksum.",
+    "type":         "bool",
+    "default":      false
+},
 {
     "name":         "operatorIDType",
     "shortDesc":    "Operator ID type",
@@ -166,4 +173,4 @@
     "default":      0
 }
 ]
-}
+}

src/Settings/RemoteIDSettings.cc

@@ -19,6 +19,7 @@ DECLARE_SETTINGGROUP(RemoteID, "RemoteID")
 
 DECLARE_SETTINGSFACT(RemoteIDSettings,  enable)
 DECLARE_SETTINGSFACT(RemoteIDSettings,  operatorID)
+DECLARE_SETTINGSFACT(RemoteIDSettings,  operatorIDValid)
 DECLARE_SETTINGSFACT(RemoteIDSettings,  operatorIDType)
 DECLARE_SETTINGSFACT(RemoteIDSettings,  sendOperatorID)
 DECLARE_SETTINGSFACT(RemoteIDSettings,  selfIDFree)
@@ -37,4 +38,4 @@ DECLARE_SETTINGSFACT(RemoteIDSettings,  longitudeFixed)
 DECLARE_SETTINGSFACT(RemoteIDSettings,  altitudeFixed)
 DECLARE_SETTINGSFACT(RemoteIDSettings,  classificationType)
 DECLARE_SETTINGSFACT(RemoteIDSettings,  categoryEU)
-DECLARE_SETTINGSFACT(RemoteIDSettings,  classEU)
+DECLARE_SETTINGSFACT(RemoteIDSettings,  classEU)

src/Settings/RemoteIDSettings.h

@@ -20,6 +20,7 @@ class RemoteIDSettings : public SettingsGroup
 
     DEFINE_SETTINGFACT(enable)
     DEFINE_SETTINGFACT(operatorID)
+    DEFINE_SETTINGFACT(operatorIDValid)
     DEFINE_SETTINGFACT(operatorIDType)
     DEFINE_SETTINGFACT(sendOperatorID)
     DEFINE_SETTINGFACT(selfIDFree)
@@ -39,4 +40,4 @@ class RemoteIDSettings : public SettingsGroup
     DEFINE_SETTINGFACT(classificationType)
     DEFINE_SETTINGFACT(categoryEU)
     DEFINE_SETTINGFACT(classEU)
-};
+};

src/Vehicle/RemoteIDManager.cc

@@ -66,13 +66,20 @@ RemoteIDManager::RemoteIDManager(Vehicle* vehicle)
     // Assign vehicle sysid and compid. GCS must target these messages to autopilot, and autopilot will redirect them to RID device
     _targetSystem = _vehicle->id();
     _targetComponent = _vehicle->compId();
+
+    if (_settings->operatorIDValid()->rawValue() == true) {
+        // If it was already checked, we can flag this as good to go.
+        // We don't do a fresh verification because we don't store the private part of the ID.
+        _operatorIDGood = true;
+        operatorIDGoodChanged();
+    }
 }
 
 void RemoteIDManager::mavlinkMessageReceived(mavlink_message_t& message )
 {
     switch (message.msgid) {
     // So far we are only listening to this one, as heartbeat won't be sent if connected by CAN
-    case MAVLINK_MSG_ID_OPEN_DRONE_ID_ARM_STATUS: 
+    case MAVLINK_MSG_ID_OPEN_DRONE_ID_ARM_STATUS:
         _handleArmStatus(message);
     default:
         break;
@@ -99,7 +106,7 @@ void RemoteIDManager::_handleArmStatus(mavlink_message_t& message)
         }
     }
 
-    // Sanity check, only get messages from same sysid 
+    // Sanity check, only get messages from same sysid
     if (_vehicle->id() != message.sysid) {
         return;
     }
@@ -113,8 +120,7 @@ void RemoteIDManager::_handleArmStatus(mavlink_message_t& message)
     if (!_commsGood) {
         _commsGood = true;
         _sendMessagesTimer.start();     // Start sending our messages
-        _checkGCSBasicID();             // Check if basicID is good to send 
-        checkOperatorID();              // Check if OperatorID is good in case we want to send it from start because of the settings
+        _checkGCSBasicID();             // Check if basicID is good to send
         emit commsGoodChanged();
         qCDebug(RemoteIDManagerLog) << "Receiving ODID_ARM_STATUS from RID device";
     }
@@ -159,22 +165,22 @@ void RemoteIDManager::_sendMessages()
     if (!_settings->enable()->rawValue().toBool()) {
         return;
     }
-    
+
     // We always try to send System
     _sendSystem();
-    
+
     // only send it if the information is correct and the tickbox in settings is set
     if (_GCSBasicIDValid && _settings->sendBasicID()->rawValue().toBool()) {
         _sendBasicID();
     }
-    
+
     // We only send selfID if the pilot wants it or in case of a declared emergency. If an emergency is cleared
     // we also keep sending the message, to be sure the non emergency state makes it up to the vehicle
     if (_settings->sendSelfID()->rawValue().toBool() || _emergencyDeclared || _enforceSendingSelfID) {
         _sendSelfIDMsg();
     }
 
-    // We only send the OperatorID if the pilot wants it or if the region we have set is europe. 
+    // We only send the OperatorID if the pilot wants it or if the region we have set is europe.
     // To be able to send it, it needs to be filled correclty
     if ((_settings->sendOperatorID()->rawValue().toBool() || (_settings->region()->rawValue().toInt() == Region::EU)) && _operatorIDGood) {
         _sendOperatorID();
@@ -230,7 +236,7 @@ const char* RemoteIDManager::_getSelfIDDescription()
                 descriptionToSend = bytesEmergency.data();
         }
     }
-    
+
     return descriptionToSend;
 }
 
@@ -266,7 +272,7 @@ void RemoteIDManager::_sendSystem()
     QGeoPositionInfo    geoPositionInfo;
     // Location types:
     // 0 -> TAKEOFF (not supported yet)
-    // 1 -> LIVE GNNS 
+    // 1 -> LIVE GNNS
     // 2 -> FIXED
     if (_settings->locationType()->rawValue().toUInt() == LocationTypes::FIXED) {
         // For FIXED location, we first check that the values are valid. Then we populate our position
@@ -301,7 +307,7 @@ void RemoteIDManager::_sendSystem()
                 return;
             }
 
-            // If the GPS data is older than ALLOWED_GPS_DELAY we cannot use this data 
+            // If the GPS data is older than ALLOWED_GPS_DELAY we cannot use this data
             if (_lastGeoPositionTimeStamp.msecsTo(QDateTime::currentDateTime().currentDateTimeUtc()) > ALLOWED_GPS_DELAY) {
                 if (_gcsGPSGood) {
                     _gcsGPSGood = false;
@@ -319,12 +325,12 @@ void RemoteIDManager::_sendSystem()
             emit gcsGPSGoodChanged();
             qCDebug(RemoteIDManagerLog) << "GCS GPS data is not valid.";
         }
-        
+
     }
 
     WeakLinkInterfacePtr weakLink = _vehicle->vehicleLinkManager()->primaryLink();
     SharedLinkInterfacePtr sharedLink = weakLink.lock();
-    
+
     if (sharedLink) {
         mavlink_message_t msg;
 
@@ -366,10 +372,10 @@ void RemoteIDManager::_sendBasicID()
 
     if (sharedLink) {
         mavlink_message_t msg;
-        
+
         QString basicIDTemp = _settings->basicID()->rawValue().toString();
         QByteArray ba = basicIDTemp.toLocal8Bit();
-        // To make sure the buffer is large enough to fit the message. It will add padding bytes if smaller, or exclude the extra ones if bigger 
+        // To make sure the buffer is large enough to fit the message. It will add padding bytes if smaller, or exclude the extra ones if bigger
         ba.resize(MAVLINK_MSG_OPEN_DRONE_ID_BASIC_ID_FIELD_UAS_ID_LEN);
 
         mavlink_msg_open_drone_id_basic_id_pack_chan(_mavlink->getSystemId(),
@@ -398,18 +404,85 @@ void RemoteIDManager::_checkGCSBasicID()
     }
 }
 
-void RemoteIDManager::checkOperatorID()
+void RemoteIDManager::checkOperatorID(const QString& operatorID)
+{
+    // We overwrite the fact that is also set by the text input but we want to update
+    // after every letter rather than when editing is done.
+    // We check whether it actually changed to avoid triggering this on startup.
+    if (operatorID != _settings->operatorID()->rawValueString()) {
+        _settings->operatorIDValid()->setRawValue(_isEUOperatorIDValid(operatorID));
+    }
+}
+
+void RemoteIDManager::setOperatorID()
 {
     QString operatorID = _settings->operatorID()->rawValue().toString();
 
-    if (!operatorID.isEmpty() && (_settings->operatorIDType()->rawValue().toInt() >= 0)) {
-        _operatorIDGood = true;
+    if (_settings->region()->rawValue().toInt() == Region::EU) {
+        // Save for next time because we don't save the private part,
+        // so we can't re-verify next time and just trust the value
+        // in the settings.
+        _operatorIDGood = _settings->operatorIDValid()->rawValue() == true;
+        if (_operatorIDGood) {
+            // Strip private part
+            _settings->operatorID()->setRawValue(operatorID.sliced(0, 16));
+        }
+
     } else {
-        _operatorIDGood = false;
+        // Otherwise, we just check if there is anything entered
+        _operatorIDGood =
+            (!operatorID.isEmpty() && (_settings->operatorIDType()->rawValue().toInt() >= 0));
     }
+
     emit operatorIDGoodChanged();
 }
 
+bool RemoteIDManager::_isEUOperatorIDValid(const QString& operatorID) const
+{
+    const bool containsDash = operatorID.contains('-');
+    if (!(operatorID.length() == 20 && containsDash) && !(operatorID.length() == 19 && !containsDash)) {
+        qCDebug(RemoteIDManagerLog) << "OperatorID not long enough";
+        return false;
+    }
+
+    const QString countryCode = operatorID.sliced(0,3);
+    if (!countryCode.isUpper()) {
+        qCDebug(RemoteIDManagerLog) << "OperatorID country code not uppercase";
+        return false;
+    }
+
+    const QString number = operatorID.sliced(3, 12);
+    const QChar checksum = operatorID.at(15);
+    const QString secret = containsDash ? operatorID.sliced(17, 3) : operatorID.sliced(16, 3);
+    const QString combination = number + secret;
+
+    const QChar result = _calculateLuhnMod36(combination);
+
+    const bool valid = (result == checksum);
+    qCDebug(RemoteIDManagerLog) << "Operator ID checksum " << (valid ? "valid" : "invalid");
+    return valid;
+}
+
+QChar RemoteIDManager::_calculateLuhnMod36(const QString& input) const {
+    const int n = 36;
+    const QString alphabet = "0123456789abcdefghijklmnopqrstuvwxyz";
+
+    int sum = 0;
+    int factor = 2;
+
+    for (int i = input.length() - 1; i >= 0; i--) {
+        int codePoint = alphabet.indexOf(input[i]);
+        int addend = factor * codePoint;
+        factor = (factor == 2) ? 1 : 2;
+        addend = (addend / n) + (addend % n);
+        sum += addend;
+    }
+
+    int remainder = sum % n;
+    int checkCodePoint = (n - remainder) % n;
+    return alphabet.at(checkCodePoint);
+}
+
 void RemoteIDManager::setEmergency(bool declare)
 {
     _emergencyDeclared = declare;
@@ -427,4 +500,4 @@ void RemoteIDManager::_updateLastGCSPositionInfo(QGeoPositionInfo update)
     if (update.isValid()) {
         _lastGeoPositionTimeStamp = update.timestamp().toUTC();
     }
-}
+}

src/Vehicle/RemoteIDManager.h

@@ -22,7 +22,7 @@ Q_DECLARE_LOGGING_CATEGORY(RemoteIDManagerLog)
 class RemoteIDSettings;
 class QGCPositionManager;
 
-// Supporting Opend Dron ID protocol
+// Supporting Open Drone ID protocol
 class RemoteIDManager : public QObject
 {
     Q_OBJECT
@@ -39,8 +39,8 @@ class RemoteIDManager : public QObject
     Q_PROPERTY (bool    operatorIDGood      READ operatorIDGood     NOTIFY operatorIDGoodChanged)
 
 
-    // Check that the information filled by the pilot operatorID is good
-    Q_INVOKABLE void checkOperatorID();
+    Q_INVOKABLE void checkOperatorID(const QString& operatorID);
+    Q_INVOKABLE void setOperatorID();
 
     // Declare emergency
     Q_INVOKABLE void setEmergency(bool declare);
@@ -84,7 +84,7 @@ private slots:
 private:
     void _handleArmStatus(mavlink_message_t& message);
 
-    // Self ID 
+    // Self ID
     void        _sendSelfIDMsg ();
     const char* _getSelfIDDescription();
 
@@ -97,7 +97,10 @@ private slots:
 
     // Basic ID
     void        _sendBasicID();
-
+
+    bool _isEUOperatorIDValid(const QString& operatorID) const;
+    QChar _calculateLuhnMod36(const QString& input) const;
+
     MAVLinkProtocol*    _mavlink;
     Vehicle*            _vehicle;
     RemoteIDSettings*   _settings;
@@ -119,10 +122,10 @@ private slots:
 
     // After emergency cleared, this makes sure the non emergency selfID message makes it to the vehicle
     bool        _enforceSendingSelfID;
-    
+
     static const uint8_t* _id_or_mac_unknown;
 
     // Timers
     QTimer _odidTimeoutTimer;
     QTimer _sendMessagesTimer;
-};
+};