Fix #238.

This fixes PR #238 (which was only included in the v4.1.0 release). It
fixes the time (replaces int type by time.Duration) and fixes the
last-seen comparison clause. It also cleans up the internal variable
naming.

Author: brocaar

cmd/chirpstack-gateway-bridge/cmd/configfile.go

@@ -92,7 +92,7 @@ type="{{ .Backend.Type }}"
   # ChirpStack Gateway Bridge keeps a list of connected gateways. If a gateway does not send any
   # UDP data within the configured timeout, then ChirpStack Gateway Bridge will consider the gateway
   # disconnected and it will unsubscribe from the gateway MQTT topic and cleanup the UDP docket. 
-  connection_timeout_duration={{ .Backend.SemtechUDP.CleanupDuration }}
+  connection_timeout_duration="{{ .Backend.SemtechUDP.ConnectionTimeoutDuration }}"
 
   # Cache expiration
   #

cmd/chirpstack-gateway-bridge/cmd/root.go

@@ -39,7 +39,7 @@ func init() {
 	viper.SetDefault("general.log_level", 4)
 	viper.SetDefault("backend.type", "semtech_udp")
 	viper.SetDefault("backend.semtech_udp.udp_bind", "0.0.0.0:1700")
-	viper.SetDefault("backend.semtech_udp.cleanup_duration", time.Minute)
+	viper.SetDefault("backend.semtech_udp.connection_timeout_duration", time.Minute)
 
 	viper.SetDefault("backend.semtech_udp.cache_default_expiration", 15*time.Second)
 	viper.SetDefault("backend.semtech_udp.cache_cleanup_interval", 15*time.Second)

internal/backend/semtechudp/backend.go

@@ -67,8 +67,8 @@ func NewBackend(conf config.Config) (*Backend, error) {
 		conn:        conn,
 		udpSendChan: make(chan udpPacket),
 		gateways: gateways{
-			gateways:        make(map[lorawan.EUI64]gateway),
-			cleanupDuration: time.Duration(conf.Backend.SemtechUDP.CleanupDuration),
+			gateways:                  make(map[lorawan.EUI64]gateway),
+			connectionTimeoutDuration: conf.Backend.SemtechUDP.ConnectionTimeoutDuration,
 		},
 		fakeRxTime:   conf.Backend.SemtechUDP.FakeRxTime,
 		skipCRCCheck: conf.Backend.SemtechUDP.SkipCRCCheck,

internal/backend/semtechudp/registry.go

@@ -27,8 +27,8 @@ type gateway struct {
 // gateways contains the gateways registry.
 type gateways struct {
 	sync.RWMutex
-	gateways        map[lorawan.EUI64]gateway
-	cleanupDuration time.Duration
+	gateways                  map[lorawan.EUI64]gateway
+	connectionTimeoutDuration time.Duration
 
 	subscribeEventFunc func(events.Subscribe)
 }
@@ -79,7 +79,7 @@ func (c *gateways) cleanup() error {
 	defer c.Unlock()
 
 	for gatewayID := range c.gateways {
-		if c.gateways[gatewayID].lastSeen.Before(time.Now().Add(c.cleanupDuration)) {
+		if c.gateways[gatewayID].lastSeen.Before(time.Now().Add(-1 * c.connectionTimeoutDuration)) {
 			disconnectCounter().Inc()
 
 			if c.subscribeEventFunc != nil {

internal/config/config.go

@@ -21,12 +21,12 @@ type Config struct {
 		Type string `mapstructure:"type"`
 
 		SemtechUDP struct {
-			UDPBind                string        `mapstructure:"udp_bind"`
-			SkipCRCCheck           bool          `mapstructure:"skip_crc_check"`
-			FakeRxTime             bool          `mapstructure:"fake_rx_time"`
-			CleanupDuration        int           `mapstructure:"connection_timeout_duration"`
-			CacheDefaultExpiration time.Duration `mapstructure:"cache_default_expiration"`
-			CacheCleanupInterval   time.Duration `mapstructure:"cache_cleanup_interval"`
+			UDPBind                   string        `mapstructure:"udp_bind"`
+			SkipCRCCheck              bool          `mapstructure:"skip_crc_check"`
+			FakeRxTime                bool          `mapstructure:"fake_rx_time"`
+			ConnectionTimeoutDuration time.Duration `mapstructure:"connection_timeout_duration"`
+			CacheDefaultExpiration    time.Duration `mapstructure:"cache_default_expiration"`
+			CacheCleanupInterval      time.Duration `mapstructure:"cache_cleanup_interval"`
 		} `mapstructure:"semtech_udp"`
 
 		BasicStation struct {