Fix: sanitize battery manufacturer name string

If the string contains control characters for some reason, the browser
will reject the json with the error `bad control character in string
literal`.

This adds a setManufacturer function that validates the string is ASCII
and will cut off the string at the first non-ascii character.

Pylontech: `PYLON` (50 59 4C 4F 4E 20 20 20)
Pytes: `PYTES` (50 59 54 45 53)
Deye: `DY001` (44 59 30 30 31 03 E8 03)

See #1226 (comment)

include/BatteryStats.h

@@ -67,13 +67,15 @@ class BatteryStats {
             _lastUpdateCurrent = _lastUpdate = timestamp;
         }
 
-        String _manufacturer = "unknown";
+        void setManufacturer(const String& m);
+
         String _hwversion = "";
         String _fwversion = "";
         String _serial = "";
         uint32_t _lastUpdate = 0;
 
     private:
+        String _manufacturer = "unknown";
         uint32_t _lastMqttPublish = 0;
         float _soc = 0;
         uint8_t _socPrecision = 0; // decimal places
@@ -98,7 +100,6 @@ class PylontechBatteryStats : public BatteryStats {
         float getChargeCurrentLimitation() const { return _chargeCurrentLimitation; } ;
 
     private:
-        void setManufacturer(String&& m) { _manufacturer = std::move(m); }
         void setLastUpdate(uint32_t ts) { _lastUpdate = ts; }
 
         float _chargeVoltage;
@@ -137,7 +138,6 @@ class PytesBatteryStats : public BatteryStats {
         float getChargeCurrentLimitation() const { return _chargeCurrentLimit; } ;
 
     private:
-        void setManufacturer(String&& m) { _manufacturer = std::move(m); }
         void setLastUpdate(uint32_t ts) { _lastUpdate = ts; }
         void updateSerial() {
             if (!_serialPart1.isEmpty() && !_serialPart2.isEmpty()) {

src/BatteryStats.cpp

@@ -54,6 +54,19 @@ static void addLiveViewAlarm(JsonVariant& root, std::string const& name,
     root["issues"][name] = 2;
 }
 
+void BatteryStats::setManufacturer(const String& m)
+{
+    String sanitized(m);
+    for (int i = 0; i < sanitized.length(); i++) {
+        char c = sanitized[i];
+        if (c < 0x20 || c >= 0x80) {
+            sanitized.remove(i); // Truncate string
+            break;
+        }
+    }
+    _manufacturer = std::move(sanitized);
+}
+
 bool BatteryStats::updateAvailable(uint32_t since) const
 {
     if (_lastUpdate == 0) { return false; } // no data at all processed yet
@@ -475,18 +488,18 @@ void JkBmsBatteryStats::updateFrom(JkBms::DataPointContainer const& dp)
 {
     using Label = JkBms::DataPointLabel;
 
-    _manufacturer = "JKBMS";
+    setManufacturer("JKBMS");
     auto oProductId = dp.get<Label::ProductId>();
     if (oProductId.has_value()) {
         // the first twelve chars are expected to be the "User Private Data"
         // setting (see smartphone app). the remainder is expected be the BMS
         // name, which can be changed at will using the smartphone app. so
         // there is not always a "JK" in this string. if there is, we still cut
         // the string there to avoid possible regressions.
-        _manufacturer = oProductId->substr(12).c_str();
+        setManufacturer(String(oProductId->substr(12).c_str()));
         auto pos = oProductId->rfind("JK");
         if (pos != std::string::npos) {
-            _manufacturer = oProductId->substr(pos).c_str();
+            setManufacturer(String(oProductId->substr(pos).c_str()));
         }
     }
 
@@ -558,7 +571,7 @@ void VictronSmartShuntStats::updateFrom(VeDirectShuntController::data_t const& s
     _timeToGo = shuntData.TTG / 60;
     _chargedEnergy = static_cast<float>(shuntData.H18) / 100;
     _dischargedEnergy = static_cast<float>(shuntData.H17) / 100;
-    _manufacturer = String("Victron ") + shuntData.getPidAsString().data();
+    setManufacturer(String("Victron ") + shuntData.getPidAsString().data());
     _temperature = shuntData.T;
     _tempPresent = shuntData.tempPresent;
     _midpointVoltage = static_cast<float>(shuntData.VM) / 1000;

src/PylontechCanReceiver.cpp

@@ -106,7 +106,7 @@ void PylontechCanReceiver::onMessage(twai_message_t rx_message)
                 MessageOutput.printf("[Pylontech] Manufacturer: %s\r\n", manufacturer.c_str());
             }
 
-            _stats->setManufacturer(std::move(manufacturer));
+            _stats->setManufacturer(manufacturer);
             break;
         }
 

src/PytesCanReceiver.cpp

@@ -127,7 +127,7 @@ void PytesCanReceiver::onMessage(twai_message_t rx_message)
                 MessageOutput.printf("[Pytes] Manufacturer: %s\r\n", manufacturer.c_str());
             }
 
-            _stats->setManufacturer(std::move(manufacturer));
+            _stats->setManufacturer(manufacturer);
             break;
         }