feat: add mDNS service for the API, so it can be discovered by esp32

pom.xml

@@ -95,6 +95,11 @@
 		      <artifactId>mariadb-java-client</artifactId>
 		      <version>1.5.7</version>
 		</dependency>
+		<dependency>
+			<groupId>org.jmdns</groupId>
+			<artifactId>jmdns</artifactId>
+			<version>3.5.9</version>
+		</dependency>
 	</dependencies>
 
 	<build>

src/main/java/com/pedro/sphynx/domain/dnsService.java

@@ -0,0 +1,82 @@
+package com.pedro.sphynx.domain;
+
+import java.net.InetAddress;
+import java.net.NetworkInterface;
+import java.util.Enumeration;
+
+import javax.jmdns.*;
+
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Component;
+
+import jakarta.annotation.PostConstruct;
+import jakarta.annotation.PreDestroy;
+
+@Component
+public class dnsService {
+
+    // Getting mdns variables from application.properties
+
+    @Value("${mdns.service.type}")
+    private String serviceType;
+
+    @Value("${mdns.service.name}")
+    private String serviceName; 
+
+    private JmDNS jmdns;
+    private int serviceNumber = 0; // If exists more than one interface on PC it concatenates the servicenumber in the serviceName so it won't conflict
+    private InetAddress ipAddress; // IP address that will start the mDNS service
+
+    @PostConstruct
+    public void registerService() {
+        try {
+            // Get all network interfaces available in the host
+            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
+            while (interfaces.hasMoreElements()) {
+                NetworkInterface networkInterface = interfaces.nextElement(); // choses an network interface from the list
+
+                // If the interface is on and is not loopback (localhost, 127.0.0.1, ::1, etc), continues
+                if (networkInterface.isUp() && !networkInterface.isLoopback()) {
+                    String nomeServico = serviceName + Integer.toString(serviceNumber); // concatenate the serviceNumber in the serviceName
+
+                    // get all ip addresses for the network interface chosen before
+                    Enumeration<InetAddress> Addresses = networkInterface.getInetAddresses();
+                    while (Addresses.hasMoreElements()){
+                        ipAddress = Addresses.nextElement(); // assign ipAddress with an ip from the list
+                        String ip = ipAddress.toString();
+
+                        // check with regex if the ip is an ipv4 (must be ipv4, ipv6 won't work), then leaves
+                        if (ip.matches("^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$")){
+                            break;
+                        }
+                    }
+
+                    // create the mDNS service with the desired ipv4 chosen before
+                    jmdns = JmDNS.create(ipAddress);
+
+                    // set service parameters (http._tcp, name, port and description)
+                    ServiceInfo serviceInfo = ServiceInfo.create(serviceType, nomeServico, 8080, "Sphynx API");
+                    jmdns.registerService(serviceInfo);
+                    serviceNumber++;
+                }
+            }
+            System.out.println("MDNS SERVICE UP");
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+
+    @PreDestroy
+    public void unregisterService() {
+        // unregister all mDNS services before shutting the api down
+        if (jmdns != null) {
+            jmdns.unregisterAllServices();
+            try {
+                jmdns.close();
+            } catch (Exception e) {
+                e.printStackTrace();
+            }
+        }
+    }
+}

src/main/resources/application.properties

@@ -4,5 +4,7 @@ spring.datasource.password=${DATABASE_PASSWORD:root}
 spring.flyway.enabled=true
 spring.flyway.locations=classpath:db/migration
 spring.flyway.baseline-on-migrate=true
+mdns.service.type=_http._tcp.local.
+mdns.service.name=sphynxapi
 
 server.error.include-stacktrace=never