Try to make some of the suggested changes

Signed-off-by: TheKodeToad <TheKodeToad@proton.me>

launcher/minecraft/MinecraftInstance.cpp

@@ -192,7 +192,7 @@ void MinecraftInstance::loadSpecificSettings()
     m_settings->registerSetting("JoinServerOnLaunch", false);
     m_settings->registerSetting("JoinServerOnLaunchAddress", "");
 
-	m_settings->registerSetting("LegacySkinFix", true);
+    m_settings->registerSetting("LegacySkinFix", true);
 
     qDebug() << "Instance-type specific settings were loaded!";
 
@@ -441,7 +441,9 @@ QStringList MinecraftInstance::javaArguments()
     args << "-Duser.language=en";
 
     if (javaVersion.isModular() && traits().contains("legacySkins") && settings()->get("LegacySkinFix").toBool())
-        args << "--add-opens" << "java.base/java.net=ALL-UNNAMED";
+        // allow reflective access to java.net - required by the skin fix
+        args << "--add-opens"
+             << "java.base/java.net=ALL-UNNAMED";
 
     return args;
 }

libraries/launcher/CMakeLists.txt

@@ -23,8 +23,7 @@ set(SRC
     org/prismlauncher/utils/JsonParser.java
     org/prismlauncher/utils/Parameters.java
     org/prismlauncher/utils/ReflectionUtils.java
-    org/prismlauncher/utils/url/NullConnection.java
-    org/prismlauncher/utils/url/UrlUtils.java
+    org/prismlauncher/utils/UrlUtils.java
     org/prismlauncher/utils/logging/Level.java
     org/prismlauncher/utils/logging/Log.java
     net/minecraft/Launcher.java

libraries/launcher/org/prismlauncher/fix/skins/Handler.java

@@ -45,8 +45,7 @@ import java.util.Map;
 
 import org.prismlauncher.utils.Base64;
 import org.prismlauncher.utils.JsonParser;
-import org.prismlauncher.utils.url.NullConnection;
-import org.prismlauncher.utils.url.UrlUtils;
+import org.prismlauncher.utils.UrlUtils;
 
 @SuppressWarnings("unchecked")
 final class Handler extends URLStreamHandler {
@@ -71,10 +70,6 @@ final class Handler extends URLStreamHandler {
     @Override
     protected URLConnection openConnection(URL address, Proxy proxy) throws IOException {
         address = redirect(address);
-
-        if (address == null)
-            return NullConnection.INSTANCE;
-
         return UrlUtils.openHttpConnection(address, proxy);
     }
 

libraries/launcher/org/prismlauncher/fix/skins/SkinFix.java

@@ -42,8 +42,8 @@ import java.net.URLStreamHandlerFactory;
 import org.prismlauncher.fix.Fix;
 import org.prismlauncher.utils.Base64;
 import org.prismlauncher.utils.Parameters;
+import org.prismlauncher.utils.UrlUtils;
 import org.prismlauncher.utils.logging.Log;
-import org.prismlauncher.utils.url.UrlUtils;
 
 /**
  * Fixes skins by redirecting to other URLs.

libraries/launcher/org/prismlauncher/utils/UrlUtils.java

@@ -33,7 +33,7 @@
  *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-package org.prismlauncher.utils.url;
+package org.prismlauncher.utils;
 
 import java.io.IOException;
 import java.lang.invoke.MethodHandle;
@@ -47,8 +47,8 @@ import java.net.URLStreamHandler;
 import org.prismlauncher.utils.logging.Log;
 
 /**
- * A utility class for URLs which uses reflection to access hidden methods.
- * Unfortunately not supported on newer Java versions.
+ * A utility class for URLs which uses reflection to access constructors for
+ * internal classes.
  */
 public final class UrlUtils {
 
@@ -57,12 +57,12 @@ public final class UrlUtils {
 
     static {
         try {
-            // invoke URL.getURLStreamHandler to obtain some of the default handlers before
-            // they are overridden
+            // we first obtain the stock URLStreamHandler for http as we overwrite it later
             Method getURLStreamHandler = URL.class.getDeclaredMethod("getURLStreamHandler", String.class);
             getURLStreamHandler.setAccessible(true);
             http = (URLStreamHandler) getURLStreamHandler.invoke(null, "http");
 
+            // we next find the openConnection method
             Method openConnectionReflect = URLStreamHandler.class.getDeclaredMethod("openConnection", URL.class,
                     Proxy.class);
             openConnectionReflect.setAccessible(true);
@@ -97,7 +97,7 @@ public final class UrlUtils {
         } catch (IOException | Error | RuntimeException e) {
             throw e; // rethrow if possible
         } catch (Throwable e) {
-            throw new Error(e); // otherwise, wrap in Error
+            throw new AssertionError(e); // oh dear! this isn't meant to happen
         }
     }
 

libraries/launcher/org/prismlauncher/utils/url/NullConnection.java

@@ -1,66 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-only
-/*
- *  Prism Launcher - Minecraft Launcher
- *  Copyright (C) 2022 TheKodeToad <TheKodeToad@proton.me>
- *
- *  This program is free software: you can redistribute it and/or modify
- *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation, version 3.
- *
- *  This program is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU General Public License for more details.
- *
- *  Linking this library statically or dynamically with other modules is
- *  making a combined work based on this library. Thus, the terms and
- *  conditions of the GNU General Public License cover the whole
- *  combination.
- *
- *  As a special exception, the copyright holders of this library give
- *  you permission to link this library with independent modules to
- *  produce an executable, regardless of the license terms of these
- *  independent modules, and to copy and distribute the resulting
- *  executable under terms of your choice, provided that you also meet,
- *  for each linked independent module, the terms and conditions of the
- *  license of that module. An independent module is a module which is
- *  not derived from or based on this library. If you modify this
- *  library, you may extend this exception to your version of the
- *  library, but you are not obliged to do so. If you do not wish to do
- *  so, delete this exception statement from your version.
- *
- *  You should have received a copy of the GNU General Public License
- *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-
-package org.prismlauncher.utils.url;
-
-import java.io.IOException;
-import java.net.HttpURLConnection;
-
-/**
- * Spoof 404 response from server to avoid unnecessary requests.
- */
-public final class NullConnection extends HttpURLConnection {
-
-    public static final NullConnection INSTANCE = new NullConnection();
-
-    public NullConnection() {
-        super(null);
-    }
-
-    @Override
-    public void connect() throws IOException {
-        responseCode = 404;
-    }
-
-    @Override
-    public void disconnect() {
-    }
-
-    @Override
-    public boolean usingProxy() {
-        return false;
-    }
-
-}