refactor: ProxyAgnosticMojangResolver

ProxyAgnosticMojangResolver serves as a cleaner implementation of the hasJoined static method from previous commit. All the reflection involved was removed due to no longer being necessary. This way, a lot cleaner code could be made. All the inner workings remained the same. For more information on how it works, check out ProxyAgnosticMojangResolver.java.

core/src/main/java/com/github/games647/fastlogin/core/mojang/ProxyAgnosticMojangResolver.java

@@ -0,0 +1,64 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015-2022 games647 and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.github.games647.fastlogin.core.mojang;
+
+import com.github.games647.craftapi.model.auth.Verification;
+import com.github.games647.craftapi.resolver.MojangResolver;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.net.InetAddress;
+import java.util.Optional;
+
+/**
+ * An extension to {@link MojangResolver} which allows connection using transparent reverse proxies.
+ * The significant difference is that unlike MojangResolver from the CraftAPI implementation, which sends the "ip" parameter
+ * when the hostIp parameter is an IPv4 address, but skips it for IPv6, this implementation leaves out the "ip" parameter
+ * also for IPv4, effectively enabling transparent proxies to work.
+ * @author games647, Enginecrafter77
+ */
+public class ProxyAgnosticMojangResolver extends MojangResolver {
+	@Override
+	public Optional<Verification> hasJoined(String username, String serverHash, InetAddress hostIp) throws IOException
+	{
+		String url = String.format("https://sessionserver.mojang.com/session/minecraft/hasJoined?username=%s&serverId=%s", username, serverHash);
+
+		HttpURLConnection conn = this.getConnection(url);
+		int responseCode = conn.getResponseCode();
+
+		Verification verification = null;
+		if(responseCode != 204)
+			verification = this.parseRequest(conn, this::parseVerification);
+		return Optional.ofNullable(verification);
+	}
+
+	// Functional implementation of InputStreamAction
+	protected Verification parseVerification(InputStream input) throws IOException
+	{
+		return this.readJson(input, Verification.class);
+	}
+}

core/src/main/java/com/github/games647/fastlogin/core/shared/FastLoginCore.java

@@ -33,6 +33,7 @@ import com.github.games647.fastlogin.core.TickingRateLimiter;
 import com.github.games647.fastlogin.core.hooks.AuthPlugin;
 import com.github.games647.fastlogin.core.hooks.DefaultPasswordGenerator;
 import com.github.games647.fastlogin.core.hooks.PasswordGenerator;
+import com.github.games647.fastlogin.core.mojang.ProxyAgnosticMojangResolver;
 import com.github.games647.fastlogin.core.storage.MySQLStorage;
 import com.github.games647.fastlogin.core.storage.SQLStorage;
 import com.github.games647.fastlogin.core.storage.SQLiteStorage;
@@ -83,7 +84,8 @@ public class FastLoginCore<P extends C, C, T extends PlatformPlugin<C>> {
     private final Collection<UUID> pendingConfirms = new HashSet<>();
     private final T plugin;
 
-    private final MojangResolver resolver = new MojangResolver();
+    //private final MojangResolver resolver = new MojangResolver();
+    private final MojangResolver resolver = new ProxyAgnosticMojangResolver();
 
     private Configuration config;
     private SQLStorage storage;