[nanoleaf] Suppress ipv6 addr in controller discovery (openhab#17724)

* stabilize nanoleaf binding:suppress ipv6 addresses in controller discovery

Signed-off-by: Stefan Höhn <[email protected]>

Author: stefan-hoehn

bundles/org.openhab.binding.nanoleaf/README.md

@@ -132,22 +132,8 @@ The controller thing has the following parameters:
 **Important note on the topic of IPV6 ip addresses:**
 
 With firmware version 8.5.2 or newer, panels may change between being OFFLINE and ONLINE.
-This is due to the fact that if they are discovered with IPv6 addresses, the binding is not able to correctly send API requests to the devices.
-It is therefore recommended to disable IPv6 on the openHAB server.
-
-This can e.g. be achieved on openHABian the following way:
-
-```shell
-sudo nano /etc/sysctl.conf`
-```
-
-Add the following at the bottom of the file:
-
-```ini
-net.ipv6.conf.all.disable_ipv6 = 1
-net.ipv6.conf.default.disable_ipv6 = 1
-net.ipv6.conf.lo.disable_ipv6 = 1
-```
+This is because if they are discovered with IPv6 addresses, the binding is not able to correctly send API requests to the devices which leads to an unstable behaviour.
+To avoid this, the binding will only discover devices based on their IPv4 address.
 
 Reboot your server after the change.
 

bundles/org.openhab.binding.nanoleaf/src/main/java/org/openhab/binding/nanoleaf/internal/discovery/NanoleafMDNSDiscoveryParticipant.java

@@ -14,6 +14,8 @@
 
 import static org.openhab.binding.nanoleaf.internal.NanoleafBindingConstants.*;
 
+import java.net.InetAddress;
+import java.net.UnknownHostException;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
@@ -66,6 +68,15 @@ public String getServiceType() {
         }
         final Map<String, Object> properties = new HashMap<>(2);
         String host = service.getHostAddresses()[0];
+        try {
+            if (InetAddress.getByName(host).getAddress().length != 4) {
+                logger.debug("Ignoring IPv6 address for nanoleaf controllers: {}", host);
+                return null;
+            }
+        } catch (UnknownHostException e) {
+            logger.warn("Error while checking IP address for nanoleaf controller: {}", host);
+            return null;
+        }
         properties.put(CONFIG_ADDRESS, host);
         int port = service.getPort();
         properties.put(CONFIG_PORT, port);