Add support for SRV records (#6982)

* SRV record support

* respect the formatting II

* avoid blocking call

* Add android support

* switch to stripped down version of dnsjava

* move srv lookup from `Net` to `NetProvider`

* random optimizations

* bump arc and restart the thing

* reimplement using ArcDns

* Update core/src/mindustry/net/ArcNetProvider.java

Co-authored-by: buthed010203 <naguiar010203@gmail.com>

* Update ArcNetProvider.java

Co-authored-by: buthed010203 <naguiar010203@gmail.com>

core/src/mindustry/net/ArcNetProvider.java

@@ -5,10 +5,12 @@ import arc.func.*;
 import arc.math.*;
 import arc.net.*;
 import arc.net.FrameworkMessage.*;
+import arc.net.dns.*;
 import arc.struct.*;
 import arc.util.*;
 import arc.util.Log.*;
 import arc.util.io.*;
+import mindustry.*;
 import mindustry.net.Net.*;
 import mindustry.net.Packets.*;
 import net.jpountz.lz4.*;
@@ -17,6 +19,7 @@ import java.io.*;
 import java.net.*;
 import java.nio.*;
 import java.nio.channels.*;
+import java.util.*;
 import java.util.concurrent.*;
 
 import static mindustry.Vars.*;
@@ -189,8 +192,27 @@ public class ArcNetProvider implements NetProvider{
     @Override
     public void pingHost(String address, int port, Cons<Host> valid, Cons<Exception> invalid){
         try{
-            DatagramSocket socket = new DatagramSocket();
+            var host = pingHostImpl(address, port);
+            Core.app.post(() -> valid.get(host));
+        }catch(IOException e){
+            if(port == Vars.port){
+                for(var record : ArcDns.getSrvRecords("_mindustry._tcp." + address)){
+                    try{
+                        var host = pingHostImpl(record.target, record.port);
+                        Core.app.post(() -> valid.get(host));
+                        return;
+                    }catch(IOException ignored){
+                    }
+                }
+            }
+            Core.app.post(() -> invalid.get(e));
+        }
+    }
+
+    private Host pingHostImpl(String address, int port) throws IOException{
+        try(DatagramSocket socket = new DatagramSocket()){
             long time = Time.millis();
+
             socket.send(new DatagramPacket(new byte[]{-2, 1}, 2, InetAddress.getByName(address), port));
             socket.setSoTimeout(2000);
 
@@ -199,10 +221,8 @@ public class ArcNetProvider implements NetProvider{
 
             ByteBuffer buffer = ByteBuffer.wrap(packet.getData());
             Host host = NetworkIO.readServerData((int)Time.timeSinceMillis(time), packet.getAddress().getHostAddress(), buffer);
-
+            host.port = port;
-            Core.app.post(() -> valid.get(host));
+            return host;
-        }catch(Exception e){
-            Core.app.post(() -> invalid.get(e));
         }
     }
 

core/src/mindustry/net/Net.java

@@ -325,6 +325,7 @@ public class Net{
 
     /**
      * Pings a host in a pooled thread. If an error occurred, failed() should be called with the exception.
+     * If the port is the default mindustry port, SRV records are checked too.
      */
     public void pingHost(String address, int port, Cons<Host> valid, Cons<Exception> failed){
         pingExecutor.submit(() -> provider.pingHost(address, port, valid, failed));
@@ -375,7 +376,10 @@ public class Net{
          */
         void discoverServers(Cons<Host> callback, Runnable done);
 
-        /** Ping a host. If an error occurred, failed() should be called with the exception. This method should block. */
+        /**
+         * Ping a host. If an error occurred, failed() should be called with the exception. This method should block.
+         * If the port is the default mindustry port (6567), SRV records are checked too.
+         */
         void pingHost(String address, int port, Cons<Host> valid, Cons<Exception> failed);
 
         /** Host a server at specified port. */
@@ -393,5 +397,4 @@ public class Net{
             closeServer();
         }
     }
-
 }

core/src/mindustry/ui/dialogs/JoinDialog.java

@@ -133,7 +133,7 @@ public class JoinDialog extends BaseDialog{
                 if(!buttons[0].childrenPressed()){
                     if(server.lastHost != null){
                         Events.fire(new ClientPreConnectEvent(server.lastHost));
-                        safeConnect(server.ip, server.port, server.lastHost.version);
+                        safeConnect(server.lastHost.address, server.lastHost.port, server.lastHost.version);
                     }else{
                         connect(server.ip, server.port);
                     }
@@ -410,7 +410,6 @@ public class JoinDialog extends BaseDialog{
                 int resport = address.contains(":") ? Strings.parseInt(address.split(":")[1]) : port;
                 net.pingHost(resaddress, resport, res -> {
                     if(refreshes != cur) return;
-                    res.port = resport;
 
                     //add header
                     if(groupTable[0] == null){