add server pinger

src/main/java/cc.fascinated/common/DNSUtils.java

@@ -0,0 +1,59 @@
+package cc.fascinated.common;
+
+import lombok.NonNull;
+import lombok.SneakyThrows;
+import lombok.experimental.UtilityClass;
+import org.xbill.DNS.Record;
+import org.xbill.DNS.*;
+
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+
+/**
+ * @author Braydon
+ */
+@UtilityClass
+public final class DNSUtils {
+    private static final String SRV_QUERY_PREFIX = "_minecraft._tcp.%s";
+
+    /**
+     * Resolve the hostname to an {@link InetSocketAddress}.
+     *
+     * @param hostname the hostname to resolve
+     * @return the resolved {@link InetSocketAddress}
+     */
+    @SneakyThrows
+    public static InetSocketAddress resolveSRV(@NonNull String hostname) {
+        Record[] records = new Lookup(SRV_QUERY_PREFIX.formatted(hostname), Type.SRV).run(); // Resolve SRV records
+        if (records == null) { // No records exist
+            return null;
+        }
+        String host = null;
+        int port = -1;
+        for (Record record : records) {
+            SRVRecord srv = (SRVRecord) record;
+            host = srv.getTarget().toString().replaceFirst("\\.$", "");
+            port = srv.getPort();
+        }
+        return host == null ? null :  new InetSocketAddress(host, port);
+    }
+
+    /**
+     * Resolve the hostname to an {@link InetAddress}.
+     *
+     * @param hostname the hostname to resolve
+     * @return the resolved {@link InetAddress}
+     */
+    @SneakyThrows
+    public static InetAddress resolveA(@NonNull String hostname) {
+        Record[] records = new Lookup(hostname, Type.A).run(); // Resolve A records
+        if (records == null) { // No records exist
+            return null;
+        }
+        InetAddress address = null;
+        for (Record record : records) {
+            address = ((ARecord) record).getAddress();
+        }
+        return address;
+    }
+}