Merge pull request #159 from yushijinhun/develop

Release v1.1.44
2022-05-03 21:40:08 +08:00 · 2022-05-03 21:40:08 +08:00 · ddd5081660
parent 74b3e6e322 dc35c04474
commit ddd5081660
13 changed files with 357 additions and 105 deletions
--- a/README.en.md
+++ b/README.en.md
@ -77,6 +77,9 @@ Configure Minecraft server with the following JVM parameter:
     - Mojang namespace
     - Legacy skin API polyfill

+-Dauthlibinjector.httpdPort={port}
+    Sets the port used by the local HTTP server, defaults to 0 (randomly chosen).
+
 -Dauthlibinjector.noShowServerName
    Do not show authentication server name in Minecraft menu screen.
    By default, authlib-injector alters --versionType parameter to display the authentication server name.
@ -94,4 +97,12 @@ Configure Minecraft server with the following JVM parameter:
       * Realms (allowed if the option is disabled)
       * Telemetry (turned off if the option is disabled)
       * Profanity filter (turned off if the option is disabled)
+
+-Dauthlibinjector.profileKey={default|enabled|disabled}
+    Whether to enable the profile signing key feature. This feature is introduced in 22w17a, and is used to implement the multiplayer secure chat signing.
+    If this this feature is enabled, Minecraft will send a POST request to /minecraftservices/player/certificates to retrieve the key pair issued by the authentication server.
+    It's enabled by default if the authentication server sends feature.enable_profile_key option.
+
+    If the profile signing key isn't present, the player will be unable to join servers that enable enforce-secure-profile=true option.
+    And other players' Minecraft client will log a warning when receiving an unsigned chat message.
 ```
--- a/README.md
+++ b/README.md
@ -37,7 +37,7 @@ gradle

    需要注意的是, authlib-injector 的日志是不会输出到 Minecraft 服务端/客户端的日志文件中的.

-    每次启动时，日志文件都会被清空. 如果有多个进程使用同一个日志文件, 则只有最早启动的会成功打开日志文件.
+    每次启动时, 日志文件都会被清空. 如果有多个进程使用同一个日志文件, 则只有最早启动的会成功打开日志文件.

 -Dauthlibinjector.mojangNamespace={default|enabled|disabled}
    设置是否启用 Mojang 命名空间 (@mojang 后缀).
@ -85,6 +85,9 @@ gradle
     - Mojang 命名空间
     - 旧式皮肤 API polyfill

+-Dauthlibinjector.httpdPort={端口号}
+    设置内置 HTTP 服务器使用的端口号, 默认为 0 (随机分配).
+
 -Dauthlibinjector.noShowServerName
    不要在 Minecraft 主界面展示验证服务器名称.
    默认情况下, authlib-injector 通过更改 --versionType 参数来在 Minecraft 主界面显示验证服务器名称, 使用本选项可以禁用该功能.
@ -101,6 +104,14 @@ gradle
       * 领域权限 (禁用后默认允许)
       * 遥测 (禁用后默认关闭)
       * 冒犯性内容过滤 (禁用后默认关闭)
+
+-Dauthlibinjector.profileKey={default|enabled|disabled}
+    是否启用消息签名密钥对功能, 这一功能在 22w17a 引入, 用于多人游戏中聊天消息的数字签名.
+    启用此功能后, Minecraft 会向 /minecraftservices/player/certificates 发送 POST 请求, 以获取由验证服务器颁发的密钥对.
+    此功能需要验证服务器支持, 若验证服务器未设置 feature.enable_profile_key 选项, 则该功能默认禁用.
+
+    当缺少消息签名密钥时, 玩家将无法进入设置了 enforce-secure-profile=true 选项的服务器.
+    而当其他玩家的客户端在收到无有效签名的聊天消息时, 会在日志中记录警告.
 ```

 ## 捐助
--- a/src/main/java/moe/yushi/authlibinjector/AuthlibInjector.java
+++ b/src/main/java/moe/yushi/authlibinjector/AuthlibInjector.java
@ -44,6 +44,7 @@ import java.util.Set;
 import java.util.stream.Stream;
 import moe.yushi.authlibinjector.httpd.DefaultURLRedirector;
 import moe.yushi.authlibinjector.httpd.LegacySkinAPIFilter;
+import moe.yushi.authlibinjector.httpd.ProfileKeyFilter;
 import moe.yushi.authlibinjector.httpd.AntiFeaturesFilter;
 import moe.yushi.authlibinjector.httpd.QueryProfileFilter;
 import moe.yushi.authlibinjector.httpd.QueryUUIDsFilter;
@ -248,6 +249,11 @@ public final class AuthlibInjector {
 			filters.add(new AntiFeaturesFilter());
 		}

+		boolean profileKeyDefault = Boolean.TRUE.equals(config.getMeta().get("feature.enable_profile_key"));
+		if (!Config.profileKey.isEnabled(profileKeyDefault)) {
+			filters.add(new ProfileKeyFilter());
+		}
+
 		return filters;
 	}

@ -255,7 +261,7 @@ public final class AuthlibInjector {
 		URLProcessor urlProcessor = new URLProcessor(createFilters(config), new DefaultURLRedirector(config));

 		ClassTransformer transformer = new ClassTransformer();
-		transformer.ignores.addAll(Config.ignoredPackages);
+		transformer.setIgnores(Config.ignoredPackages);

 		if (Config.dumpClass) {
 			transformer.listeners.add(new DumpClassListener(Paths.get("").toAbsolutePath()));
--- a/src/main/java/moe/yushi/authlibinjector/Config.java
+++ b/src/main/java/moe/yushi/authlibinjector/Config.java
@ -60,7 +60,9 @@ public final class Config {
 	public static FeatureOption mojangNamespace;
 	public static FeatureOption legacySkinPolyfill;
 	public static FeatureOption mojangAntiFeatures;
+	public static FeatureOption profileKey;
 	public static boolean noShowServerName;
+	public static int httpdPort;

 	private static void initDebugOptions() {
 		String prop = System.getProperty("authlibinjector.debug");
@ -105,34 +107,6 @@ public final class Config {
 			"com.sun.",
 			"sun.",
 			"net.java.",
-
-			"com.google.",
-			"com.ibm.",
-			"com.jcraft.jogg.",
-			"com.jcraft.jorbis.",
-			"com.oracle.",
-			"com.paulscode.",
-
-			"org.GNOME.",
-			"org.apache.",
-			"org.graalvm.",
-			"org.jcp.",
-			"org.json.",
-			"org.lwjgl.",
-			"org.objectweb.asm.",
-			"org.w3c.",
-			"org.xml.",
-			"org.yaml.snakeyaml.",
-
-			"gnu.trove.",
-			"io.netty.",
-			"it.unimi.dsi.fastutil.",
-			"javassist.",
-			"jline.",
-			"joptsimple.",
-			"oracle.",
-			"oshi.",
-			"paulscode.",
 	};

 	private static void initIgnoredPackages() {
@ -204,7 +178,9 @@ public final class Config {
 		mojangNamespace = parseFeatureOption("authlibinjector.mojangNamespace");
 		legacySkinPolyfill = parseFeatureOption("authlibinjector.legacySkinPolyfill");
 		mojangAntiFeatures = parseFeatureOption("authlibinjector.mojangAntiFeatures");
+		profileKey = parseFeatureOption("authlibinjector.profileKey");
 		httpdDisabled = System.getProperty("authlibinjector.disableHttpd") != null;
 		noShowServerName = System.getProperty("authlibinjector.noShowServerName") != null;
+		httpdPort = Integer.getInteger("authlibinjector.httpdPort", 0);
 	}
 }
--- a/src/main/java/moe/yushi/authlibinjector/httpd/DebugApiEndpoint.java
+++ b/src/main/java/moe/yushi/authlibinjector/httpd/DebugApiEndpoint.java
@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2022  Haowei Wen <yushijinhun@gmail.com> and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package moe.yushi.authlibinjector.httpd;
+
+import static moe.yushi.authlibinjector.util.IOUtils.CONTENT_TYPE_JSON;
+import moe.yushi.authlibinjector.AuthlibInjector;
+import moe.yushi.authlibinjector.internal.fi.iki.elonen.IHTTPSession;
+import moe.yushi.authlibinjector.internal.fi.iki.elonen.Response;
+import moe.yushi.authlibinjector.internal.fi.iki.elonen.Status;
+import moe.yushi.authlibinjector.internal.org.json.simple.JSONObject;
+import moe.yushi.authlibinjector.transform.PerformanceMetrics;
+
+/**
+ * Authlib-injector's debug API
+ */
+public class DebugApiEndpoint {
+
+	public Response serve(IHTTPSession session) {
+		if (session.getUri().equals("/debug/metrics") && session.getMethod().equals("GET")) {
+			PerformanceMetrics metrics = AuthlibInjector.getClassTransformer().performanceMetrics;
+			JSONObject response = new JSONObject();
+			response.put("totalTime", metrics.getTotalTime());
+			response.put("matchTime", metrics.getMatchTime());
+			response.put("scanTime", metrics.getScanTime());
+			response.put("analysisTime", metrics.getAnalysisTime());
+			response.put("classesScanned", metrics.getClassesScanned());
+			response.put("classesSkipped", metrics.getClassesSkipped());
+			return Response.newFixedLength(Status.OK, CONTENT_TYPE_JSON, response.toJSONString());
+		} else {
+			return Response.newFixedLength(Status.NOT_FOUND, null, null);
+		}
+	}
+}
--- a/src/main/java/moe/yushi/authlibinjector/httpd/ProfileKeyFilter.java
+++ b/src/main/java/moe/yushi/authlibinjector/httpd/ProfileKeyFilter.java
@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2022  Haowei Wen <yushijinhun@gmail.com> and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package moe.yushi.authlibinjector.httpd;
+
+import java.io.IOException;
+import java.util.Optional;
+import moe.yushi.authlibinjector.internal.fi.iki.elonen.IHTTPSession;
+import moe.yushi.authlibinjector.internal.fi.iki.elonen.Response;
+import moe.yushi.authlibinjector.internal.fi.iki.elonen.Status;
+
+/**
+ * Intercepts Minecraft's request to https://api.minecraftservices.com/player/certificates,
+ * and returns an empty response.
+ */
+public class ProfileKeyFilter implements URLFilter {
+
+	@Override
+	public boolean canHandle(String domain) {
+		return domain.equals("api.minecraftservices.com");
+	}
+
+	@Override
+	public Optional<Response> handle(String domain, String path, IHTTPSession session) throws IOException {
+		if (domain.equals("api.minecraftservices.com") && path.equals("/player/certificates") && session.getMethod().equals("POST")) {
+			return Optional.of(Response.newFixedLength(Status.NO_CONTENT, null, null));
+		}
+		return Optional.empty();
+	}
+
+}
--- a/src/main/java/moe/yushi/authlibinjector/httpd/URLProcessor.java
+++ b/src/main/java/moe/yushi/authlibinjector/httpd/URLProcessor.java
@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2020  Haowei Wen <yushijinhun@gmail.com> and contributors
+ * Copyright (C) 2022  Haowei Wen <yushijinhun@gmail.com> and contributors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
@ -37,6 +37,7 @@ import java.util.Optional;
 import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import moe.yushi.authlibinjector.Config;
 import moe.yushi.authlibinjector.internal.fi.iki.elonen.IHTTPSession;
 import moe.yushi.authlibinjector.internal.fi.iki.elonen.IStatus;
 import moe.yushi.authlibinjector.internal.fi.iki.elonen.NanoHTTPD;
@ -67,6 +68,10 @@ public class URLProcessor {
 	 * @return the transformed URL, or empty if it doesn't need to be transformed
 	 */
 	public Optional<String> transformURL(String inputUrl) {
+		if (!inputUrl.startsWith("http")) {
+			// fast path
+			return Optional.empty();
+		}
 		Matcher matcher = URL_REGEX.matcher(inputUrl);
 		if (!matcher.find()) {
 			return Optional.empty();
@ -98,6 +103,7 @@ public class URLProcessor {
 		return redirector.redirect(domain, path);
 	}

+	private DebugApiEndpoint debugApi = new DebugApiEndpoint();
 	private volatile NanoHTTPD httpd;
 	private final Object httpdLock = new Object();

@ -117,9 +123,13 @@ public class URLProcessor {
 	}

 	private NanoHTTPD createHttpd() {
-		return new NanoHTTPD("127.0.0.1", 0) {
+		return new NanoHTTPD("127.0.0.1", Config.httpdPort) {
 			@Override
 			public Response serve(IHTTPSession session) {
+				if (session.getUri().startsWith("/debug/")) {
+					return debugApi.serve(session);
+				}
+
 				Matcher matcher = LOCAL_URL_REGEX.matcher(session.getUri());
 				if (matcher.find()) {
 					String protocol = matcher.group("protocol");
--- a/src/main/java/moe/yushi/authlibinjector/transform/ClassTransformer.java
+++ b/src/main/java/moe/yushi/authlibinjector/transform/ClassTransformer.java
@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2021  Haowei Wen <yushijinhun@gmail.com> and contributors
+ * Copyright (C) 2022  Haowei Wen <yushijinhun@gmail.com> and contributors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
@ -27,11 +27,10 @@ import java.lang.instrument.ClassFileTransformer;
 import java.lang.instrument.IllegalClassFormatException;
 import java.security.ProtectionDomain;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
-import java.util.Set;
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
 import org.objectweb.asm.ClassReader;
 import org.objectweb.asm.ClassVisitor;
@ -43,58 +42,59 @@ public class ClassTransformer implements ClassFileTransformer {

 	public final List<TransformUnit> units = new CopyOnWriteArrayList<>();
 	public final List<ClassLoadingListener> listeners = new CopyOnWriteArrayList<>();
-	public final Set<String> ignores = Collections.newSetFromMap(new ConcurrentHashMap<>());
+	public final PerformanceMetrics performanceMetrics = new PerformanceMetrics();
+	private String[] ignores = new String[0];

-	private static class TransformContextImpl implements TransformContext {
+	private class TransformHandle {

-		private final String className;
+		private class TransformContextImpl implements TransformContext {

-		public boolean isInterface;
-		public boolean modifiedMark;
-		public int minVersionMark = -1;
-		public int upgradedVersionMark = -1;
-		public boolean callbackMetafactoryRequested = false;
+			public boolean modifiedMark;
+			public int minVersionMark = -1;
+			public int upgradedVersionMark = -1;
+			public boolean callbackMetafactoryRequested = false;

-		public TransformContextImpl(String className) {
-			this.className = className;
-		}
+			@Override
+			public void markModified() {
+				modifiedMark = true;
+			}

-		@Override
-		public void markModified() {
-			modifiedMark = true;
-		}
+			@Override
+			public void requireMinimumClassVersion(int version) {
+				if (this.minVersionMark < version) {
+					this.minVersionMark = version;
+				}
+			}

-		@Override
-		public void requireMinimumClassVersion(int version) {
-			if (this.minVersionMark < version) {
-				this.minVersionMark = version;
+			@Override
+			public void upgradeClassVersion(int version) {
+				if (this.upgradedVersionMark < version) {
+					this.upgradedVersionMark = version;
+				}
+			}
+
+			@Override
+			public Handle acquireCallbackMetafactory() {
+				this.callbackMetafactoryRequested = true;
+				return new Handle(
+						H_INVOKESTATIC,
+						className.replace('.', '/'),
+						CallbackSupport.METAFACTORY_NAME,
+						CallbackSupport.METAFACTORY_SIGNATURE,
+						TransformHandle.this.isInterface());
+			}
+
+			@Override
+			public List<String> getStringConstants() {
+				return TransformHandle.this.getStringConstants();
 			}
 		}

-		@Override
-		public void upgradeClassVersion(int version) {
-			if (this.upgradedVersionMark < version) {
-				this.upgradedVersionMark = version;
-			}
-		}
-
-		@Override
-		public Handle acquireCallbackMetafactory() {
-			this.callbackMetafactoryRequested = true;
-			return new Handle(
-					H_INVOKESTATIC,
-					className.replace('.', '/'),
-					CallbackSupport.METAFACTORY_NAME,
-					CallbackSupport.METAFACTORY_SIGNATURE,
-					isInterface);
-		}
-	}
-
-	private static class TransformHandle {
-
 		private final String className;
 		private final ClassLoader classLoader;
 		private byte[] classBuffer;
+		private ClassReader cachedClassReader;
+		private List<String> cachedConstants;

 		private List<TransformUnit> appliedTransformers;
 		private int minVersion = -1;
@ -107,30 +107,82 @@ public class ClassTransformer implements ClassFileTransformer {
 			this.classLoader = classLoader;
 		}

-		public void accept(TransformUnit unit) {
-			ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS);
-			TransformContextImpl ctx = new TransformContextImpl(className);
+		private ClassReader getClassReader() {
+			if (cachedClassReader == null)
+				cachedClassReader = new ClassReader(classBuffer);
+			return cachedClassReader;
+		}

-			Optional<ClassVisitor> optionalVisitor = unit.transform(classLoader, className, writer, ctx);
-			if (optionalVisitor.isPresent()) {
-				ClassReader reader = new ClassReader(classBuffer);
-				ctx.isInterface = (reader.getAccess() & ACC_INTERFACE) != 0;
-				reader.accept(optionalVisitor.get(), 0);
-				if (ctx.modifiedMark) {
-					log(INFO, "Transformed [" + className + "] with [" + unit + "]");
-					if (appliedTransformers == null) {
-						appliedTransformers = new ArrayList<>();
-					}
-					appliedTransformers.add(unit);
-					classBuffer = writer.toByteArray();
-					if (ctx.minVersionMark > this.minVersion) {
-						this.minVersion = ctx.minVersionMark;
-					}
-					if (ctx.upgradedVersionMark > this.upgradedVersion) {
-						this.upgradedVersion = ctx.upgradedVersionMark;
-					}
-					this.addCallbackMetafactory |= ctx.callbackMetafactoryRequested;
+		private boolean isInterface() {
+			return (getClassReader().getAccess() & ACC_INTERFACE) != 0;
+		}
+
+		private List<String> getStringConstants() {
+			if (cachedConstants == null)
+				cachedConstants = extractStringConstants(getClassReader());
+			return cachedConstants;
+		}
+
+		public void accept(TransformUnit... units) {
+			long t0 = System.nanoTime();
+
+			ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS);
+
+			TransformContextImpl[] ctxs = new TransformContextImpl[units.length];
+			ClassVisitor chain = writer;
+			for (int i = units.length - 1; i >= 0; i--) {
+				TransformContextImpl ctx = new TransformContextImpl();
+				Optional<ClassVisitor> visitor = units[i].transform(classLoader, className, chain, ctx);
+				if (!visitor.isPresent())
+					continue;
+				ctxs[i] = ctx;
+				chain = visitor.get();
+			}
+
+			long t1 = System.nanoTime();
+			synchronized (performanceMetrics) {
+				performanceMetrics.scanTime += t1 - t0;
+			}
+
+			if (chain == writer)
+				return;
+
+			t0 = System.nanoTime();
+
+			getClassReader().accept(chain, 0);
+
+			t1 = System.nanoTime();
+			synchronized (performanceMetrics) {
+				performanceMetrics.analysisTime += t1 - t0;
+			}
+
+			boolean modified = false;
+			for (int i = 0; i < units.length; i++) {
+				TransformContextImpl ctx = ctxs[i];
+				if (ctx == null || !ctx.modifiedMark)
+					continue;
+
+				log(INFO, "Transformed [" + className + "] with [" + units[i] + "]");
+
+				if (appliedTransformers == null)
+					appliedTransformers = new ArrayList<>();
+				appliedTransformers.add(units[i]);
+
+				if (ctx.minVersionMark > this.minVersion) {
+					this.minVersion = ctx.minVersionMark;
 				}
+				if (ctx.upgradedVersionMark > this.upgradedVersion) {
+					this.upgradedVersion = ctx.upgradedVersionMark;
+				}
+				this.addCallbackMetafactory |= ctx.callbackMetafactoryRequested;
+
+				modified = true;
+			}
+
+			if (modified) {
+				classBuffer = writer.toByteArray();
+				cachedClassReader = null;
+				cachedConstants = null;
 			}
 		}

@ -168,22 +220,42 @@ public class ClassTransformer implements ClassFileTransformer {
 	public byte[] transform(ClassLoader loader, String internalClassName, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
 		if (internalClassName != null && classfileBuffer != null) {
 			try {
+				long t0 = System.nanoTime();
+
 				String className = internalClassName.replace('/', '.');
-				for (String prefix : ignores) {
-					if (className.startsWith(prefix)) {
+				for (String ignore : ignores) {
+					if (className.startsWith(ignore)) {
 						listeners.forEach(it -> it.onClassLoading(loader, className, classfileBuffer, Collections.emptyList()));
+
+						long t1 = System.nanoTime();
+						synchronized (performanceMetrics) {
+							performanceMetrics.classesSkipped++;
+							performanceMetrics.totalTime += t1 - t0;
+							performanceMetrics.matchTime += t1 - t0;
+						}
 						return null;
 					}
 				}
+				long t1 = System.nanoTime();

 				TransformHandle handle = new TransformHandle(loader, className, classfileBuffer);
-				units.forEach(handle::accept);
+				TransformUnit[] unitsArray = units.toArray(new TransformUnit[0]);
+				handle.accept(unitsArray);
 				listeners.forEach(it -> it.onClassLoading(loader, className, handle.getFinalResult(), handle.getAppliedTransformers()));

 				Optional<byte[]> transformResult = handle.finish();
 				if (Config.printUntransformedClass && !transformResult.isPresent()) {
 					log(DEBUG, "No transformation is applied to [" + className + "]");
 				}
+
+				long t2 = System.nanoTime();
+
+				synchronized (performanceMetrics) {
+					performanceMetrics.classesScanned++;
+					performanceMetrics.totalTime += t2 - t0;
+					performanceMetrics.matchTime += t1 - t0;
+				}
+
 				return transformResult.orElse(null);
 			} catch (Throwable e) {
 				log(WARNING, "Failed to transform [" + internalClassName + "]", e);
@ -191,4 +263,25 @@ public class ClassTransformer implements ClassFileTransformer {
 		}
 		return null;
 	}
+
+	private static List<String> extractStringConstants(ClassReader reader) {
+		List<String> constants = new ArrayList<>();
+		int constantPoolSize = reader.getItemCount();
+		char[] buf = new char[reader.getMaxStringLength()];
+		for (int idx = 1; idx < constantPoolSize; idx++) {
+			int offset = reader.getItem(idx);
+			if (offset == 0)
+				continue;
+			int type = reader.readByte(offset - 1);
+			if (type == 8) { // CONSTANT_String_info
+				String constant = (String) reader.readConst(idx, buf);
+				constants.add(constant);
+			}
+		}
+		return constants;
+	}
+
+	public void setIgnores(Collection<String> newIgnores) {
+		ignores = newIgnores.toArray(ignores);
+	}
 }
--- a/src/main/java/moe/yushi/authlibinjector/transform/LdcTransformUnit.java
+++ b/src/main/java/moe/yushi/authlibinjector/transform/LdcTransformUnit.java
@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2021  Haowei Wen <yushijinhun@gmail.com> and contributors
+ * Copyright (C) 2022  Haowei Wen <yushijinhun@gmail.com> and contributors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
@ -26,6 +26,17 @@ public abstract class LdcTransformUnit implements TransformUnit {

 	@Override
 	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext ctx) {
+		boolean matched = false;
+		for (String constant : ctx.getStringConstants()) {
+			Optional<String> transformed = transformLdc(constant);
+			if (transformed.isPresent() && !transformed.get().equals(constant)) {
+				matched = true;
+				break;
+			}
+		}
+		if (!matched)
+			return Optional.empty();
+
 		return Optional.of(new ClassVisitor(ASM9, writer) {

 			@Override
--- a/src/main/java/moe/yushi/authlibinjector/transform/PerformanceMetrics.java
+++ b/src/main/java/moe/yushi/authlibinjector/transform/PerformanceMetrics.java
@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2022  Haowei Wen <yushijinhun@gmail.com> and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package moe.yushi.authlibinjector.transform;
+
+public class PerformanceMetrics {
+
+	volatile long totalTime;
+	volatile long matchTime;
+	volatile long scanTime;
+	volatile long analysisTime;
+	volatile long classesScanned;
+	volatile long classesSkipped;
+
+	public synchronized long getTotalTime() { return totalTime; }
+	public synchronized long getMatchTime() { return matchTime; }
+	public synchronized long getScanTime() { return scanTime; }
+	public synchronized long getAnalysisTime() { return analysisTime; }
+	public synchronized long getClassesScanned() { return classesScanned; }
+	public synchronized long getClassesSkipped() { return classesSkipped; }
+}
--- a/src/main/java/moe/yushi/authlibinjector/transform/TransformContext.java
+++ b/src/main/java/moe/yushi/authlibinjector/transform/TransformContext.java
@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2020  Haowei Wen <yushijinhun@gmail.com> and contributors
+ * Copyright (C) 2022  Haowei Wen <yushijinhun@gmail.com> and contributors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
@ -16,6 +16,7 @@
 */
 package moe.yushi.authlibinjector.transform;

+import java.util.List;
 import org.objectweb.asm.Handle;

 public interface TransformContext {
@ -27,4 +28,6 @@ public interface TransformContext {
 	void upgradeClassVersion(int version);

 	Handle acquireCallbackMetafactory();
+
+	List<String> getStringConstants();
 }
--- a/src/main/java/moe/yushi/authlibinjector/transform/support/UsernameCharacterCheckTransformer.java
+++ b/src/main/java/moe/yushi/authlibinjector/transform/support/UsernameCharacterCheckTransformer.java
@ -31,6 +31,10 @@ public class UsernameCharacterCheckTransformer implements TransformUnit {

 	@Override
 	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext context) {
+		if (!context.getStringConstants().contains("Invalid characters in username")) {
+			return Optional.empty();
+		}
+
 		return Optional.of(new ClassVisitor(ASM9, writer) {
 			@Override
 			public MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) {
--- a/src/main/java/moe/yushi/authlibinjector/util/Logging.java
+++ b/src/main/java/moe/yushi/authlibinjector/util/Logging.java
@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2021  Haowei Wen <yushijinhun@gmail.com> and contributors
+ * Copyright (C) 2022  Haowei Wen <yushijinhun@gmail.com> and contributors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
@ -29,11 +29,14 @@ import java.nio.charset.Charset;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.time.Instant;
+import java.util.regex.Pattern;
 import moe.yushi.authlibinjector.Config;

 public final class Logging {
 	private Logging() {}

+	private static final Pattern CONTROL_CHARACTERS_FILTER = Pattern.compile("[\\p{Cc}&&[^\r\n\t]]");
+
 	private static final PrintStream out = System.err;
 	private static final FileChannel logfile = openLogFile();

@ -83,13 +86,12 @@ public final class Logging {
 			log += sw.toString();
 		}
 		// remove control characters to prevent messing up the console
-		log = log.replaceAll("[\\p{Cc}&&[^\r\n\t]]", "");
+		log = CONTROL_CHARACTERS_FILTER.matcher(log).replaceAll("");
 		out.println(log);

 		if (logfile != null) {
 			try {
 				logfile.write(Charset.defaultCharset().encode(log + System.lineSeparator()));
-				logfile.force(true);
 			} catch (IOException ex) {
 				out.println("[authlib-injector] [ERROR] Error writing to log file: " + ex);
 			}