Allow valueSize changes after initialization to adjust to MTU size

src/BLECharacteristic.cpp

@@ -109,6 +109,18 @@
   return 0;
 }
 
+bool BLECharacteristic::setValueSize(uint16_t valueSize) {
+  if (_local) {
+    return _local->setValueSize(valueSize);
+  }
+
+  if (_remote) {
+    //_remote->setValueLength();
+  }
+
+  return false;
+}
+
 int BLECharacteristic::valueSize() const
 {
   if (_local) {

src/BLECharacteristic.h

@@ -54,6 +54,7 @@ class BLECharacteristic  {
 
   uint8_t properties() const;
 
+  bool setValueSize(uint16_t valueSize);
   int valueSize() const;
   const uint8_t* value() const;
   int valueLength() const;

src/BLEDevice.cpp

@@ -261,6 +261,11 @@
   return _rssi;
 }
 
+uint16_t BLEDevice::getMTU() const
+{
+	return ATT.mtu(ATT.connectionHandle(_addressType, _address));
+}
+
 bool BLEDevice::connect()
 {
   return ATT.connect(_addressType, _address);

src/BLEDevice.h

@@ -28,6 +28,7 @@ enum BLEDeviceEvent {
   BLEConnected = 0,
   BLEDisconnected = 1,
   BLEDiscovered = 2,
+  BLEMtuChanged = 3,
 
   BLEDeviceLastEvent
 };
@@ -68,6 +69,7 @@ class BLEDevice {
   int manufacturerData(uint8_t value[], int length) const;
 
   virtual int rssi();
+  virtual uint16_t getMTU() const;
 
   bool connect();
   bool discoverAttributes();

src/local/BLELocalCharacteristic.cpp

@@ -89,6 +89,20 @@
   return _permissions;
 }
 
+bool BLELocalCharacteristic::setValueSize(uint16_t valueSize) {
+  if (valueSize == _valueSize) {
+    return true;
+  }
+
+  if (_valueLength > 0 && valueSize < _valueLength) {
+    return false;
+  }
+
+  _value = (uint8_t*)realloc(_value, valueSize);
+  _valueSize = valueSize;
+  return true;
+}
+
 int BLELocalCharacteristic::valueSize() const
 {
   return _valueSize;

src/local/BLELocalCharacteristic.h

@@ -42,6 +42,7 @@ class BLELocalCharacteristic : public BLELocalAttribute {
   uint8_t properties() const;
   uint8_t permissions() const;
 
+  bool setValueSize(uint16_t valueSize);
   int valueSize() const;
   const uint8_t* value() const;
   int valueLength() const;

src/local/BLELocalDevice.cpp

@@ -283,6 +283,17 @@
   return 127;
 }
 
+uint16_t BLELocalDevice::getMTU()
+{
+  BLEDevice central = ATT.central();
+
+  if (central) {
+    return central.getMTU();
+  }
+
+  return -1;
+}
+
 bool BLELocalDevice::setAdvertisedServiceUuid(const char* advertisedServiceUuid)
 {
   return _advertisingData.setAdvertisedServiceUuid(advertisedServiceUuid);

src/local/BLELocalDevice.h

@@ -47,6 +47,7 @@ class BLELocalDevice {
   virtual String address() const;
 
   virtual int rssi();
+  virtual uint16_t getMTU();
 
   virtual bool setAdvertisedServiceUuid(const char* advertisedServiceUuid);
   virtual bool setAdvertisedService(const BLEService& service);

src/utility/ATT.cpp

@@ -689,6 +689,9 @@
   for (int i = 0; i < ATT_MAX_PEERS; i++) {
     if (_peers[i].connectionHandle == connectionHandle) {
       _peers[i].mtu = mtu;
+      if (_eventHandlers[BLEMtuChanged]) {
+        _eventHandlers[BLEMtuChanged](BLEDevice(_peers[i].addressType, _peers[i].address));
+      }
       break;
     }
   }
@@ -722,6 +725,9 @@
   for (int i = 0; i < ATT_MAX_PEERS; i++) {
     if (_peers[i].connectionHandle == connectionHandle) {
       _peers[i].mtu = mtu;
+      // if (_eventHandlers[BLEMtuChanged]) {
+      //   _eventHandlers[BLEMtuChanged](BLEDevice(_peers[i].addressType, _peers[i].address));
+      // }
       break;
     }
   }

src/utility/ATT.h

@@ -169,7 +169,7 @@ class ATTClass {
     uint8_t length;
   } _pendingResp;
 
-  BLEDeviceEventHandler _eventHandlers[2];
+  BLEDeviceEventHandler _eventHandlers[BLEDeviceLastEvent];
 };
 
 extern ATTClass& ATT;