Add native Mojmap support for the spigot module (#591)

* Add native Mojmap support for the spigot module

* Don't remove spigot class name for CraftPlayer

* Also include CraftServer and CraftOfflinePlayer

Author: Novampr

core/src/main/java/org/geysermc/floodgate/util/ReflectionUtils.java

@@ -135,6 +135,39 @@ public static Class<?> getClassOrFallback(String className, String fallbackClass
         return clazz;
     }
 
+    public static Class<?> getClassOrFallback(String className, String fallbackClassName1, String fallbackClassName2) {
+        Class<?> clazz = getClassSilently(className);
+
+        if (clazz != null) {
+            if (Constants.DEBUG_MODE) {
+                System.out.println("Found class (primary): " + clazz.getName());
+            }
+            return clazz;
+        }
+
+        clazz = getClassSilently(fallbackClassName1);
+
+        if (clazz != null) {
+            if (Constants.DEBUG_MODE) {
+                System.out.println("Found class (fallback1): " + clazz.getName());
+            }
+            return clazz;
+        }
+
+        // do throw an exception when both classes couldn't be found
+        clazz = ReflectionUtils.getClassOrThrow(fallbackClassName2);
+        if (Constants.DEBUG_MODE) {
+            System.out.println("Found class (fallback2): " + clazz.getName());
+        }
+        return clazz;
+    }
+
+    @Nullable
+    @SuppressWarnings("unchecked")
+    public static <T> Class<T> getCastedClassOrFallback(String className, String fallbackClassName) {
+        return (Class<T>) getClassOrFallback(className, fallbackClassName);
+    }
+
     @Nullable
     public static <T> Constructor<T> getConstructor(Class<T> clazz, boolean declared, Class<?>... parameters) {
         try {
@@ -210,6 +243,28 @@ public static Field getField(Class<?> clazz, String fieldName) {
         return getField(clazz, fieldName, false);
     }
 
+    /**
+     * Get a field from a class, it doesn't matter if the field is public or not. This method will
+     * first try to get a declared field and if that failed it'll try to get a public field.
+     *
+     * @param clazz     the class to get the field from
+     * @param fieldName the name of the field
+     * @param fallbackFieldName the fallback incase fieldName doesn't exist
+     * @return the field if found from the name or fallback, otherwise null
+     */
+    @Nullable
+    public static Field getField(Class<?> clazz, String fieldName, String fallbackFieldName) {
+        Field field = getField(clazz, fieldName, true);
+        if (field != null) {
+            return field;
+        }
+        field = getField(clazz, fieldName, false);
+        if (field != null) {
+            return field;
+        }
+        return getField(clazz, fallbackFieldName);
+    }
+
     /**
      * Get a field from a class without having to provide a field name.
      *
@@ -418,6 +473,29 @@ public static Method getMethod(Class<?> clazz, String methodName, Class<?>... ar
         return getMethod(clazz, methodName, false, arguments);
     }
 
+    /**
+     * Get a method from a class, it doesn't matter if the method is public or not. This method will
+     * first try to get a declared method and if that fails it'll try to get a public method.
+     *
+     * @param clazz      the class to get the method from
+     * @param methodName the name of the method to find
+     * @param fallbackName the fallback instead methodName does not exist
+     * @param arguments  the classes of the method arguments
+     * @return the requested method if it has been found, otherwise null
+     */
+    @Nullable
+    public static Method getMethod(Class<?> clazz, String methodName, String fallbackName, Class<?>... arguments) {
+        Method method = getMethod(clazz, methodName, true, arguments);
+        if (method != null) {
+            return method;
+        }
+        method = getMethod(clazz, methodName, false, arguments);
+        if (method != null) {
+            return method;
+        }
+        return getMethod(clazz, fallbackName, arguments);
+    }
+
     /**
      * Get a method from a class, it doesn't matter if the method is public or not. This method will
      * first try to get a declared method and if that fails it'll try to get a public method.

spigot/src/main/java/org/geysermc/floodgate/util/ClassNames.java

@@ -114,8 +114,10 @@ public class ClassNames {
 
 
         // SpigotSkinApplier
-        Class<?> craftPlayerClass = ReflectionUtils.getClass(
-                "org.bukkit.craftbukkit." + version + "entity.CraftPlayer");
+        Class<?> craftPlayerClass = getClassOrFallback(
+                "org.bukkit.craftbukkit.entity.CraftPlayer",
+                "org.bukkit.craftbukkit." + version + "entity.CraftPlayer"
+        );
         GET_PROFILE_METHOD = getMethod(craftPlayerClass, "getProfile");
         checkNotNull(GET_PROFILE_METHOD, "Get profile method");
 
@@ -135,28 +137,35 @@ public class ClassNames {
         );
 
         SERVER_CONNECTION = getClassOrFallback(
+                "net.minecraft.server.network.ServerConnectionListener",
                 "net.minecraft.server.network.ServerConnection",
                 nmsPackage + "ServerConnection"
         );
 
         // WhitelistUtils
-        Class<?> craftServerClass = ReflectionUtils.getClass(
-                "org.bukkit.craftbukkit." + version + "CraftServer");
-        Class<OfflinePlayer> craftOfflinePlayerClass = ReflectionUtils.getCastedClass(
-                "org.bukkit.craftbukkit." + version + "CraftOfflinePlayer");
+        Class<?> craftServerClass = getClassOrFallback(
+                "org.bukkit.craftbukkit.CraftServer",
+                "org.bukkit.craftbukkit." + version + "CraftServer"
+        );
+        Class<OfflinePlayer> craftOfflinePlayerClass = ReflectionUtils.getCastedClassOrFallback(
+                "org.bukkit.craftbukkit.CraftOfflinePlayer",
+                "org.bukkit.craftbukkit." + version + "CraftOfflinePlayer"
+        );
 
         CRAFT_OFFLINE_PLAYER_CONSTRUCTOR = ReflectionUtils.getConstructor(
                 craftOfflinePlayerClass, true, craftServerClass, GameProfile.class);
 
         // SpigotDataHandler
         Class<?> networkManager = getClassOrFallback(
+                "net.minecraft.network.Connection",
                 "net.minecraft.network.NetworkManager",
                 nmsPackage + "NetworkManager"
         );
 
         SOCKET_ADDRESS = getFieldOfType(networkManager, SocketAddress.class, false);
 
         HANDSHAKE_PACKET = getClassOrFallback(
+                "net.minecraft.network.protocol.handshake.ClientIntentionPacket",
                 "net.minecraft.network.protocol.handshake.PacketHandshakingInSetProtocol",
                 nmsPackage + "PacketHandshakingInSetProtocol"
         );
@@ -165,11 +174,13 @@ public class ClassNames {
         checkNotNull(HANDSHAKE_HOST, "Handshake host");
 
         LOGIN_START_PACKET = getClassOrFallback(
+                "net.minecraft.network.protocol.login.ServerboundHelloPacket",
                 "net.minecraft.network.protocol.login.PacketLoginInStart",
                 nmsPackage + "PacketLoginInStart"
         );
 
         LOGIN_LISTENER = getClassOrFallback(
+                "net.minecraft.server.network.ServerLoginPacketListenerImpl",
                 "net.minecraft.server.network.LoginListener",
                 nmsPackage + "LoginListener"
         );
@@ -210,15 +221,15 @@ public class ClassNames {
             // We get the field by name on 1.20.2+ as there are now multiple fields of this type in network manager
 
             // PacketListener packetListener of NetworkManager
-            PACKET_LISTENER = getField(networkManager, "q");
+            PACKET_LISTENER = getField(networkManager, "packetListener", "q");
             makeAccessible(PACKET_LISTENER);
         }
         checkNotNull(PACKET_LISTENER, "Packet listener");
 
         if (IS_POST_LOGIN_HANDLER) {
             makeAccessible(CALL_PLAYER_PRE_LOGIN_EVENTS);
 
-            START_CLIENT_VERIFICATION = getMethod(LOGIN_LISTENER, "b", GameProfile.class);
+            START_CLIENT_VERIFICATION = getMethod(LOGIN_LISTENER, "startClientVerification", "b", GameProfile.class);
             checkNotNull(START_CLIENT_VERIFICATION, "startClientVerification");
             makeAccessible(START_CLIENT_VERIFICATION);
 
@@ -314,15 +325,15 @@ public class ClassNames {
                     String.class, int.class, CLIENT_INTENT);
             checkNotNull(HANDSHAKE_PACKET_CONSTRUCTOR, "Handshake packet constructor");
 
-            Field a = getField(HANDSHAKE_PACKET, "a");
+            Field a = getField(HANDSHAKE_PACKET, "STREAM_CODEC", "a");
             checkNotNull(a, "Handshake \"a\" field (protocol version, or stream codec)");
 
             if (a.getType().isPrimitive()) { // 1.20.2 - 1.20.4: a is the protocol version (int)
                 HANDSHAKE_PROTOCOL = a;
                 HANDSHAKE_PORT = getField(HANDSHAKE_PACKET, "c");
             } else { // 1.20.5: a is the stream_codec thing, so everything is shifted
-                HANDSHAKE_PROTOCOL = getField(HANDSHAKE_PACKET, "b");
-                HANDSHAKE_PORT = getField(HANDSHAKE_PACKET, "d");
+                HANDSHAKE_PROTOCOL = getField(HANDSHAKE_PACKET, "protocolVersion", "b");
+                HANDSHAKE_PORT = getField(HANDSHAKE_PACKET, "port", "d");
             }
 
             checkNotNull(HANDSHAKE_PROTOCOL, "Handshake protocol");