Add support for allowlisting of sensors by MAC

Currently the exporter will publish data about every single
encountered sensor. This change adds support for MAC address based
allowlist so that only selected sensors can be listened for. When
the list is empty, all sensors are exported just like without this
feature.

cmd/gbcsdpd/main.go

@@ -67,11 +67,21 @@ func main() {
 		log.Fatalf("Failed to listen for BLE advertisements: %v", err)
 	}
 
+	sensorsAllowlist := make(map[string]bool)
+	for _, addr := range conf.SensorAllowlist {
+		sensorsAllowlist[addr.String()] = true
+	}
+
 	for adv := range advListener.Advertisements() {
 		data, ok := adv.ManufacturerData[ruuviManufacturerID]
 		if !ok {
 			continue
 		}
+
+		if len(sensorsAllowlist) > 0 && !sensorsAllowlist[adv.Address.String()] {
+			continue
+		}
+
 		ruuviData, err := ruuviparse.Parse(data)
 		if err != nil {
 			log.Printf("Failed to parse ruuvi data: %v", err)

pkg/config/config.go

@@ -20,6 +20,7 @@ import (
 	"crypto/x509"
 	"fmt"
 	"io/ioutil"
+	"net"
 	"path"
 	"regexp"
 	"strings"
@@ -35,8 +36,9 @@ type Sink interface{}
 
 // Config contains the full parsed configuration for the application.
 type Config struct {
-	Adapter string
-	Sinks   []Sink
+	Adapter         string
+	Sinks           []Sink
+	SensorAllowlist []net.HardwareAddr
 }
 
 // RateLimit is configruation for the rate limiting of sinks.
@@ -294,6 +296,13 @@ func Read(configPath string) (*Config, error) {
 	} else {
 		config.Adapter = *fconfig.Adapter
 	}
+	for _, address := range fconfig.SensorAllowlist {
+		hwAddr, err := net.ParseMAC(address)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse entry in sensor allow list: %v", err)
+		}
+		config.SensorAllowlist = append(config.SensorAllowlist, hwAddr)
+	}
 	for i, sink := range fconfig.Sinks.MQTT {
 		mqttSink, err := parseMQTTSink(path.Dir(configPath), i, sink)
 		if err != nil {

pkg/config/config_format.go

@@ -21,6 +21,9 @@ type fConfig struct {
 
 	// If none sinks are defined, a single default Stdout sink is created
 	Sinks fSinks `toml:"sinks"`
+
+	// Sensors MAC adresses allowlist. If emtpy, all sensors are allowed.
+	SensorAllowlist []string `toml:"sensor_allowlist"`
 }
 
 // Struct holds list of sinks for publications

pkg/config/config_test.go

@@ -19,6 +19,7 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"io/ioutil"
+	"net"
 	"testing"
 	"time"
 
@@ -111,6 +112,10 @@ func TestParsingCorrect(t *testing.T) {
 				RateLimit: &RateLimit{Max1In: 10 * time.Second},
 			},
 		},
+		SensorAllowlist: []net.HardwareAddr{
+			[]byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
+			[]byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xf1},
+		},
 	}
 	if diff := cmpConfig(config, expectedConfig); diff != "" {
 		t.Errorf("unexpected difference:\n%v", diff)
@@ -129,6 +134,7 @@ func TestParsingEmpty(t *testing.T) {
 				Name: "default-sink",
 			},
 		},
+		SensorAllowlist: nil,
 	}
 	if diff := cmpConfig(config, expectedConfig); diff != "" {
 		t.Errorf("unexpected difference:\n%v", diff)

pkg/config/testdata/test1/config.toml

@@ -1,5 +1,10 @@
 adapter = "hci1"
 
+sensor_allowlist = [
+	"FF:FF:FF:FF:FF:FF",
+	"ff:ff:ff:ff:ff:f1",
+]
+
 [[sinks.stdout]]
 name = "stdout sink 1"
 rate_limit.max_1_in = "90s"