Paper/patches/server/0717-Deobfuscate-stacktraces-in-log-messages-using-a-Rewr.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jason Penilla <11360596+jpenilla@users.noreply.github.com>
Date: Sun, 20 Jun 2021 18:19:09 -0700
Subject: [PATCH] Deobfuscate stacktraces in log messages using a
 RewriteAppender and a custom RewritePolicy


diff --git a/build.gradle.kts b/build.gradle.kts
index 04938bb10c35d2e424043adb7ed8fec2e42bb816..f427c6f5adf20f9e1b1fa4ab56041506d8240c92 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -1,8 +1,12 @@
 import com.github.jengelman.gradle.plugins.shadow.transformers.Log4j2PluginsCacheFileTransformer
 import com.github.jengelman.gradle.plugins.shadow.transformers.Transformer
+import io.papermc.paperweight.tasks.BaseTask
 import io.papermc.paperweight.util.Git
+import io.papermc.paperweight.util.defaultOutput
+import io.papermc.paperweight.util.openZip
 import io.papermc.paperweight.util.path
 import shadow.org.apache.logging.log4j.core.config.plugins.processor.PluginProcessor.PLUGIN_CACHE_FILE
+import java.nio.file.Files
 import java.text.SimpleDateFormat
 import java.util.Date
 import java.util.Locale
@@ -15,6 +19,14 @@ plugins {
 
 repositories {
     maven("https://libraries.minecraft.net/")
+    // Paper start
+    maven("https://maven.quiltmc.org/repository/release/") {
+        mavenContent {
+            releasesOnly()
+            includeModule("org.quiltmc", "tiny-mappings-parser")
+        }
+    }
+    // Paper end
 }
 
 dependencies {
@@ -52,6 +64,8 @@ dependencies {
 
     implementation("com.github.oshi:oshi-core:5.7.5") // Paper - fix startup delay and warning
 
+    implementation("org.quiltmc:tiny-mappings-parser:0.3.0") // Paper - needed to read mappings for stacktrace deobfuscation
+
     testImplementation("io.github.classgraph:classgraph:4.8.47") // Paper - mob goal test
     testImplementation("junit:junit:4.13.1")
     testImplementation("org.hamcrest:hamcrest-library:1.3")
@@ -115,6 +129,44 @@ tasks.shadowJar {
     transform(ModifiedLog4j2PluginsCacheFileTransformer::class.java)
 }
 
+// Paper start - include reobf mappings in jar for stacktrace deobfuscation
+abstract class IncludeMappings : BaseTask() {
+    @get:InputFile
+    abstract val inputJar: RegularFileProperty
+
+    @get:InputFile
+    abstract val mappings: RegularFileProperty
+
+    @get:OutputFile
+    abstract val outputJar: RegularFileProperty
+
+    override fun init() {
+        outputJar.convention(defaultOutput())
+    }
+
+    @TaskAction
+    private fun addMappings() {
+        outputJar.get().asFile.parentFile.mkdirs()
+        inputJar.get().asFile.copyTo(outputJar.get().asFile, overwrite = true)
+        outputJar.get().path.openZip().use { fs ->
+            val dir = fs.getPath("META-INF/mappings/")
+            Files.createDirectories(dir)
+            val target = dir.resolve("reobf.tiny")
+            Files.copy(mappings.path, target)
+        }
+    }
+}
+
+val includeMappings = tasks.register<IncludeMappings>("includeMappings") {
+    inputJar.set(tasks.shadowJar.flatMap { it.archiveFile })
+    mappings.set(tasks.reobfJar.flatMap { it.mappingsFile })
+}
+
+tasks.reobfJar {
+    inputJar.set(includeMappings.flatMap { it.outputJar })
+}
+// Paper end - include reobf mappings in jar for stacktrace deobfuscation
+
 tasks.test {
     exclude("org/bukkit/craftbukkit/inventory/ItemStack*Test.class")
 }
diff --git a/src/main/java/com/destroystokyo/paper/PaperConfig.java b/src/main/java/com/destroystokyo/paper/PaperConfig.java
index 7acf077bc131af718c7548cc29deef558c04e463..73652e403eaa419fb5b4b54bd506f246c0aa4e99 100644
--- a/src/main/java/com/destroystokyo/paper/PaperConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java
@@ -487,6 +487,11 @@ public class PaperConfig {
         enableBrigadierConsoleCompletions = getBoolean("settings.console.enable-brigadier-completions", enableBrigadierConsoleCompletions);
     }
 
+    public static boolean deobfuscateStacktraces = true;
+    private static void loggerSettings() {
+        deobfuscateStacktraces = getBoolean("settings.loggers.deobfuscate-stacktraces", deobfuscateStacktraces);
+    }
+
     public static int itemValidationDisplayNameLength = 8192;
     public static int itemValidationLocNameLength = 8192;
     public static int itemValidationLoreLineLength = 8192;
diff --git a/src/main/java/io/papermc/paper/logging/StacktraceDeobfuscatingRewritePolicy.java b/src/main/java/io/papermc/paper/logging/StacktraceDeobfuscatingRewritePolicy.java
new file mode 100644
index 0000000000000000000000000000000000000000..5293a59d17eeb711694965816857e66481ff0277
--- /dev/null
+++ b/src/main/java/io/papermc/paper/logging/StacktraceDeobfuscatingRewritePolicy.java
@@ -0,0 +1,242 @@
+package io.papermc.paper.logging;
+
+import com.destroystokyo.paper.PaperConfig;
+import com.google.common.base.Charsets;
+import com.google.common.collect.ImmutableMap;
+import com.mojang.datafixers.util.Pair;
+import it.unimi.dsi.fastutil.ints.IntArrayList;
+import it.unimi.dsi.fastutil.ints.IntList;
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import net.fabricmc.mapping.tree.ClassDef;
+import net.fabricmc.mapping.tree.MethodDef;
+import net.fabricmc.mapping.tree.TinyMappingFactory;
+import net.fabricmc.mapping.tree.TinyTree;
+import org.apache.logging.log4j.core.Core;
+import org.apache.logging.log4j.core.LogEvent;
+import org.apache.logging.log4j.core.appender.rewrite.RewritePolicy;
+import org.apache.logging.log4j.core.config.plugins.Plugin;
+import org.apache.logging.log4j.core.config.plugins.PluginFactory;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.objectweb.asm.ClassReader;
+import org.objectweb.asm.ClassVisitor;
+import org.objectweb.asm.Label;
+import org.objectweb.asm.MethodVisitor;
+import org.objectweb.asm.Opcodes;
+
+@Plugin(
+    name = "StacktraceDeobfuscatingRewritePolicy",
+    category = Core.CATEGORY_NAME,
+    elementType = "rewritePolicy",
+    printObject = true
+)
+public final class StacktraceDeobfuscatingRewritePolicy implements RewritePolicy {
+    private static final String MOJANG_PLUS_YARN_NAMESPACE = "mojang+yarn";
+    private static final String SPIGOT_NAMESPACE = "spigot";
+
+    private final @Nullable Map<String, ClassMapping> mappings;
+    private final Map<Class<?>, Map<Pair<String, String>, IntList>> lineMapCache = Collections.synchronizedMap(new LinkedHashMap<>(64, 0.75f, true) {
+        @Override
+        protected boolean removeEldestEntry(final Map.Entry<Class<?>, Map<Pair<String, String>, IntList>> eldest) {
+            return this.size() > 63;
+        }
+    });
+
+    StacktraceDeobfuscatingRewritePolicy() {
+        this.mappings = loadMappingsIfPresent();
+    }
+
+    private static @Nullable Map<String, ClassMapping> loadMappingsIfPresent() {
+        try (final InputStream mappingsInputStream = StacktraceDeobfuscatingRewritePolicy.class.getClassLoader().getResourceAsStream("mappings/reobf.tiny")) {
+            if (mappingsInputStream == null) {
+                return null;
+            }
+            final TinyTree tree = TinyMappingFactory.loadWithDetection(new BufferedReader(new InputStreamReader(mappingsInputStream, Charsets.UTF_8)));
+            final var builder = ImmutableMap.<String, ClassMapping>builder();
+
+            for (final ClassDef classDef : tree.getClasses()) {
+                final String obfClassName = classDef.getName(SPIGOT_NAMESPACE).replace('/', '.');
+                final var methodMappings = ImmutableMap.<Pair<String, String>, MethodMapping>builder();
+
+                for (final MethodDef methodDef : classDef.getMethods()) {
+                    final MethodMapping method = new MethodMapping(
+                        methodDef.getName(SPIGOT_NAMESPACE),
+                        methodDef.getName(MOJANG_PLUS_YARN_NAMESPACE),
+                        methodDef.getDescriptor(SPIGOT_NAMESPACE)
+                    );
+                    methodMappings.put(
+                        new Pair<>(method.obfName(), method.descriptor()),
+                        method
+                    );
+                }
+
+                final ClassMapping map = new ClassMapping(
+                    obfClassName,
+                    classDef.getName(MOJANG_PLUS_YARN_NAMESPACE).replace('/', '.'),
+                    methodMappings.build()
+                );
+                builder.put(map.obfName(), map);
+            }
+
+            return builder.build();
+        } catch (final IOException ex) {
+            System.err.println("Failed to load mappings for stacktrace deobfuscation.");
+            ex.printStackTrace();
+            return null;
+        }
+    }
+
+    @Override
+    public @NotNull LogEvent rewrite(final @NotNull LogEvent rewrite) {
+        if (!PaperConfig.deobfuscateStacktraces) {
+            return rewrite;
+        }
+
+        final Throwable thrown = rewrite.getThrown();
+        if (thrown != null) {
+            this.deobfuscateThrowable(thrown);
+        }
+        return rewrite;
+    }
+
+    public void deobfuscateThrowable(final Throwable throwable) {
+        throwable.setStackTrace(this.deobfuscateStacktrace(throwable.getStackTrace()));
+        final Throwable cause = throwable.getCause();
+        if (cause != null) {
+            this.deobfuscateThrowable(cause);
+        }
+        for (final Throwable suppressed : throwable.getSuppressed()) {
+            this.deobfuscateThrowable(suppressed);
+        }
+    }
+
+    public StackTraceElement[] deobfuscateStacktrace(final StackTraceElement[] traceElements) {
+        if (this.mappings == null || traceElements.length == 0) {
+            return traceElements;
+        }
+        final StackTraceElement[] result = new StackTraceElement[traceElements.length];
+        for (int i = 0; i < traceElements.length; i++) {
+            final StackTraceElement element = traceElements[i];
+
+            final String className = element.getClassName();
+            final String methodName = element.getMethodName();
+
+            final ClassMapping classMapping = this.mappings.get(className);
+            if (classMapping == null) {
+                result[i] = element;
+                continue;
+            }
+
+            final Pair<String, String> nameDescriptorPair;
+            try {
+                final Class<?> clazz = Class.forName(className);
+                nameDescriptorPair = this.determineMethodForLine(clazz, element.getLineNumber());
+            } catch (final ReflectiveOperationException ex) {
+                throw new RuntimeException(ex);
+            }
+
+            final MethodMapping methodMapping = classMapping.methodMappings().get(nameDescriptorPair);
+
+            result[i] = new StackTraceElement(
+                element.getClassLoaderName(),
+                element.getModuleName(),
+                element.getModuleVersion(),
+                classMapping.mojangName(),
+                methodMapping != null ? methodMapping.mojangName() : methodName,
+                this.mappedFileName(classMapping.mojangName()),
+                element.getLineNumber()
+            );
+        }
+        return result;
+    }
+
+    private static @NotNull Map<Pair<String, String>, IntList> buildLineMap(final @NotNull Class<?> key) {
+        final Map<Pair<String, String>, IntList> lineMap = new HashMap<>();
+        final class LineCollectingMethodVisitor extends MethodVisitor {
+            private final IntList lines = new IntArrayList();
+            private final String name;
+            private final String descriptor;
+
+            LineCollectingMethodVisitor(String name, String descriptor) {
+                super(Opcodes.ASM9);
+                this.name = name;
+                this.descriptor = descriptor;
+            }
+
+            @Override
+            public void visitLineNumber(int line, Label start) {
+                super.visitLineNumber(line, start);
+                this.lines.add(line);
+            }
+
+            @Override
+            public void visitEnd() {
+                super.visitEnd();
+                lineMap.put(new Pair<>(this.name, this.descriptor), this.lines);
+            }
+        }
+        final ClassVisitor classVisitor = new ClassVisitor(Opcodes.ASM9) {
+            @Override
+            public MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) {
+                return new LineCollectingMethodVisitor(name, descriptor);
+            }
+        };
+        try {
+            final ClassReader reader = new ClassReader(key.getName());
+            reader.accept(classVisitor, 0);
+        } catch (final IOException ex) {
+            throw new RuntimeException(ex);
+        }
+        return lineMap;
+    }
+
+    private @Nullable Pair<String, String> determineMethodForLine(final @NotNull Class<?> clazz, final int lineNumber) {
+        final Map<Pair<String, String>, IntList> lineMap = this.lineMapCache.computeIfAbsent(clazz, StacktraceDeobfuscatingRewritePolicy::buildLineMap);
+        for (final var entry : lineMap.entrySet()) {
+            final Pair<String, String> pair = entry.getKey();
+            final IntList lines = entry.getValue();
+            for (int i = 0, linesSize = lines.size(); i < linesSize; i++) {
+                final int num = lines.getInt(i);
+                if (num == lineNumber) {
+                    return pair;
+                }
+            }
+        }
+        return null;
+    }
+
+    private @NotNull String mappedFileName(final @NotNull String fullClassName) {
+        final int dot = fullClassName.lastIndexOf('.');
+        final String className = dot == -1
+            ? fullClassName
+            : fullClassName.substring(dot + 1);
+        final String rootClassName = className.split("\\$")[0];
+        return rootClassName + ".java";
+    }
+
+    @PluginFactory
+    public static @NotNull StacktraceDeobfuscatingRewritePolicy createPolicy() {
+        return new StacktraceDeobfuscatingRewritePolicy();
+    }
+
+    private record ClassMapping(
+        String obfName,
+        String mojangName,
+        Map<Pair<String, String>, MethodMapping> methodMappings
+    ) {
+    }
+
+    private record MethodMapping(
+        String obfName,
+        String mojangName,
+        String descriptor
+    ) {
+    }
+}
diff --git a/src/main/resources/log4j2.xml b/src/main/resources/log4j2.xml
index 67da1aa7a21622fb231d19dede3775a282a4a12e..f91d0df569b2f1d430ea5eee5f53779902a4f32c 100644
--- a/src/main/resources/log4j2.xml
+++ b/src/main/resources/log4j2.xml
@@ -29,15 +29,19 @@
             </Policies>
             <DefaultRolloverStrategy max="1000"/>
         </RollingRandomAccessFile>
+        <Rewrite name="rewrite">
+            <StacktraceDeobfuscatingRewritePolicy />
+            <AppenderRef ref="File"/>
+            <AppenderRef ref="TerminalConsole" level="info"/>
+            <AppenderRef ref="ServerGuiConsole" level="info"/>
+        </Rewrite>
     </Appenders>
     <Loggers>
         <Root level="info">
             <filters>
                 <MarkerFilter marker="NETWORK_PACKETS" onMatch="DENY" onMismatch="NEUTRAL" />
             </filters>
-            <AppenderRef ref="File"/>
-            <AppenderRef ref="TerminalConsole" level="info"/>
-            <AppenderRef ref="ServerGuiConsole" level="info"/>
+            <AppenderRef ref="rewrite"/>
         </Root>
     </Loggers>
 </Configuration>