Allow setting permission flags on characteristics

adapter_sd.go

@@ -34,7 +34,7 @@ var clockConfig C.nrf_clock_lf_cfg_t = C.nrf_clock_lf_cfg_t{
 }
 
 var (
-	secModeOpen       C.ble_gap_conn_sec_mode_t
+	secModeOpen       C.ble_gap_conn_sec_mode_t // No security is needed (aka open link).
 	defaultDeviceName = [6]byte{'T', 'i', 'n', 'y', 'G', 'o'}
 )
 

examples/heartrate/main.go

@@ -28,6 +28,7 @@ func main() {
 				Handle: &heartRateMeasurement,
 				UUID:   bluetooth.New16BitUUID(0x2A37), // Heart Rate Measurement
 				Value:  []byte{0, 75},                  // 75bpm
+				Flags:  bluetooth.CharacteristicReadPermission,
 			},
 		},
 	}))

gatts.go

@@ -10,7 +10,8 @@ type Service struct {
 // Characteristic is a single characteristic in a service. It has an UUID and a
 // value.
 type Characteristic struct {
-	handle uint16
+	handle      uint16
+	permissions CharacteristicPermissions
 }
 
 // CharacteristicConfig contains some parameters for the configuration of a
@@ -22,6 +23,7 @@ type CharacteristicConfig struct {
 	Handle *Characteristic
 	UUID
 	Value []byte
+	Flags CharacteristicPermissions
 }
 
 // Handle returns the numeric handle for this characteristic. This is used
@@ -29,3 +31,40 @@ type CharacteristicConfig struct {
 func (c *Characteristic) Handle() uint16 {
 	return c.handle
 }
+
+// CharacteristicPermissions lists a number of basic permissions/capabilities
+// that clients have regarding this characteristic. For example, if you want to
+// allow clients to read the value of this characteristic (a common scenario),
+// set the Read permission.
+type CharacteristicPermissions uint8
+
+// Characteristic permission bitfields.
+const (
+	CharacteristicBroadcastPermission CharacteristicPermissions = 1 << iota
+	CharacteristicReadPermission
+	CharacteristicWriteWithoutResponsePermission
+	CharacteristicWritePermission
+	CharacteristicNotifyPermission
+	CharacteristicIndicatePermission
+)
+
+// Broadcast returns whether broadcasting of the value is permitted.
+func (p CharacteristicPermissions) Broadcast() bool {
+	return p&CharacteristicBroadcastPermission != 0
+}
+
+// Read returns whether reading of the value is permitted.
+func (p CharacteristicPermissions) Read() bool {
+	return p&CharacteristicReadPermission != 0
+}
+
+// Write returns whether writing of the value with Write Request is permitted.
+func (p CharacteristicPermissions) Write() bool {
+	return p&CharacteristicWritePermission != 0
+}
+
+// WriteWithoutResponse returns whether writing of the value with Write Command
+// is permitted.
+func (p CharacteristicPermissions) WriteWithoutResponse() bool {
+	return p&CharacteristicWriteWithoutResponsePermission != 0
+}

gatts_sd.go

@@ -22,8 +22,12 @@ func (a *Adapter) AddService(service *Service) error {
 	}
 	for _, char := range service.Characteristics {
 		metadata := C.ble_gatts_char_md_t{}
-		metadata.char_props.set_bitfield_read(1)
-		metadata.char_props.set_bitfield_write(1)
+		metadata.char_props.set_bitfield_broadcast(uint8(char.Flags>>0) & 1)
+		metadata.char_props.set_bitfield_read(uint8(char.Flags>>1) & 1)
+		metadata.char_props.set_bitfield_write_wo_resp(uint8(char.Flags>>2) & 1)
+		metadata.char_props.set_bitfield_write(uint8(char.Flags>>3) & 1)
+		metadata.char_props.set_bitfield_notify(uint8(char.Flags>>4) & 1)
+		metadata.char_props.set_bitfield_indicate(uint8(char.Flags>>5) & 1)
 		handles := C.ble_gatts_char_handles_t{}
 		charUUID, errCode := char.UUID.shortUUID()
 		if errCode != 0 {
@@ -49,6 +53,7 @@ func (a *Adapter) AddService(service *Service) error {
 		}
 		if char.Handle != nil {
 			char.Handle.handle = handles.value_handle
+			char.Handle.permissions = char.Flags
 		}
 	}
 	return makeError(errCode)