it is done

core/src/mindustry/net/NetworkIO.java

@@ -0,0 +1,117 @@
+package mindustry.net;
+
+import arc.*;
+import arc.util.*;
+import mindustry.core.*;
+import mindustry.entities.type.*;
+import mindustry.game.*;
+import mindustry.io.*;
+import mindustry.maps.Map;
+
+import java.io.*;
+import java.nio.*;
+import java.util.*;
+
+import static mindustry.Vars.*;
+
+public class NetworkIO{
+
+    public static void writeWorld(Player player, OutputStream os){
+
+        try(DataOutputStream stream = new DataOutputStream(os)){
+            stream.writeUTF(JsonIO.write(state.rules));
+            SaveIO.getSaveWriter().writeStringMap(stream, world.getMap().tags);
+
+            stream.writeInt(state.wave);
+            stream.writeFloat(state.wavetime);
+
+            stream.writeInt(player.id);
+            player.write(stream);
+
+            SaveIO.getSaveWriter().writeContentHeader(stream);
+            SaveIO.getSaveWriter().writeMap(stream);
+        }catch(IOException e){
+            throw new RuntimeException(e);
+        }
+    }
+
+    public static void loadWorld(InputStream is){
+
+        try(DataInputStream stream = new DataInputStream(is)){
+            Time.clear();
+            state.rules = JsonIO.read(Rules.class, stream.readUTF());
+            world.setMap(new Map(SaveIO.getSaveWriter().readStringMap(stream)));
+
+            state.wave = stream.readInt();
+            state.wavetime = stream.readFloat();
+
+            entities.clear();
+            int id = stream.readInt();
+            player.resetNoAdd();
+            player.read(stream);
+            player.resetID(id);
+            player.add();
+
+            SaveIO.getSaveWriter().readContentHeader(stream);
+            SaveIO.getSaveWriter().readMap(stream, world.context);
+        }catch(IOException e){
+            throw new RuntimeException(e);
+        }finally{
+            content.setTemporaryMapper(null);
+        }
+    }
+
+    public static ByteBuffer writeServerData(){
+        String name = (headless ? Core.settings.getString("servername") : player.name);
+        String map = world.getMap() == null ? "None" : world.getMap().name();
+
+        ByteBuffer buffer = ByteBuffer.allocate(256);
+
+        writeString(buffer, name, 100);
+        writeString(buffer, map);
+
+        buffer.putInt(playerGroup.size());
+        buffer.putInt(state.wave);
+        buffer.putInt(Version.build);
+        writeString(buffer, Version.type);
+
+        buffer.put((byte)Gamemode.bestFit(state.rules).ordinal());
+        buffer.putInt(netServer.admins.getPlayerLimit());
+        return buffer;
+    }
+
+    public static Host readServerData(String hostAddress, ByteBuffer buffer){
+        String host = readString(buffer);
+        String map = readString(buffer);
+        int players = buffer.getInt();
+        int wave = buffer.getInt();
+        int version = buffer.getInt();
+        String vertype = readString(buffer);
+        Gamemode gamemode = Gamemode.all[buffer.get()];
+        int limit = buffer.getInt();
+
+        return new Host(host, hostAddress, map, wave, players, version, vertype, gamemode, limit);
+    }
+
+    private static void writeString(ByteBuffer buffer, String string, int maxlen){
+        byte[] bytes = string.getBytes(charset);
+        //todo truncating this way may lead to wierd encoding errors at the ends of strings...
+        if(bytes.length > maxlen){
+            bytes = Arrays.copyOfRange(bytes, 0, maxlen);
+        }
+
+        buffer.put((byte)bytes.length);
+        buffer.put(bytes);
+    }
+
+    private static void writeString(ByteBuffer buffer, String string){
+        writeString(buffer, string, 32);
+    }
+
+    private static String readString(ByteBuffer buffer){
+        short length = (short)(buffer.get() & 0xff);
+        byte[] bytes = new byte[length];
+        buffer.get(bytes);
+        return new String(bytes, charset);
+    }
+}