feat(dex-input): initial support for DEX v41 (#2128)

Author: skylot

jadx-plugins/jadx-dex-input/src/main/java/jadx/plugins/input/dex/DexFileLoader.java

@@ -20,6 +20,7 @@
 import jadx.api.plugins.utils.CommonFileUtils;
 import jadx.api.plugins.utils.ZipSecurity;
 import jadx.plugins.input.dex.sections.DexConsts;
+import jadx.plugins.input.dex.sections.DexHeaderV41;
 import jadx.plugins.input.dex.utils.DexCheckSum;
 
 public class DexFileLoader {
@@ -63,8 +64,7 @@ private List<DexReader> load(@Nullable File file, InputStream inputStream, Strin
 			if (isStartWithBytes(magic, DexConsts.DEX_FILE_MAGIC) || fileName.endsWith(".dex")) {
 				in.reset();
 				byte[] content = readAllBytes(in);
-				DexReader dexReader = loadDexReader(fileName, content);
-				return Collections.singletonList(dexReader);
+				return loadDexReaders(fileName, content);
 			}
 			if (file != null) {
 				// allow only top level zip files
@@ -76,11 +76,32 @@ private List<DexReader> load(@Nullable File file, InputStream inputStream, Strin
 		}
 	}
 
-	public DexReader loadDexReader(String fileName, byte[] content) {
+	public List<DexReader> loadDexReaders(String fileName, byte[] content) {
+		DexHeaderV41 dexHeaderV41 = DexHeaderV41.readIfPresent(content);
+		if (dexHeaderV41 != null) {
+			return DexHeaderV41.readSubDexOffsets(content, dexHeaderV41)
+					.stream()
+					.map(offset -> loadSingleDex(fileName, content, offset))
+					.collect(Collectors.toList());
+		}
+		DexReader dexReader = loadSingleDex(fileName, content, 0);
+		return Collections.singletonList(dexReader);
+	}
+
+	private DexReader loadSingleDex(String fileName, byte[] content, int offset) {
 		if (options.isVerifyChecksum()) {
-			DexCheckSum.verify(content, fileName);
+			DexCheckSum.verify(fileName, content, offset);
 		}
-		return new DexReader(getNextUniqId(), fileName, content);
+		return new DexReader(getNextUniqId(), fileName, content, offset);
+	}
+
+	/**
+	 * Since DEX v41, several sub DEX structures can be stored inside container of a single DEX file
+	 * Use {@link DexFileLoader#loadDexReaders(String, byte[])} instead.
+	 */
+	@Deprecated
+	public DexReader loadDexReader(String fileName, byte[] content) {
+		return loadSingleDex(fileName, content, 0);
 	}
 
 	private List<DexReader> collectDexFromZip(File file) {

jadx-plugins/jadx-dex-input/src/main/java/jadx/plugins/input/dex/DexInputPlugin.java

@@ -3,7 +3,6 @@
 import java.io.Closeable;
 import java.io.InputStream;
 import java.nio.file.Path;
-import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
 
@@ -48,8 +47,8 @@ public ICodeLoader loadFiles(List<Path> inputFiles, @Nullable Closeable closeabl
 
 	public ICodeLoader loadDex(byte[] content, @Nullable String fileName) {
 		String fileLabel = fileName == null ? "input.dex" : fileName;
-		DexReader dexReader = loader.loadDexReader(fileLabel, content);
-		return new DexLoadResult(Collections.singletonList(dexReader), null);
+		List<DexReader> dexReaders = loader.loadDexReaders(fileLabel, content);
+		return new DexLoadResult(dexReaders, null);
 	}
 
 	public ICodeLoader loadDexFromInputStream(InputStream in, @Nullable String fileLabel) {
@@ -62,7 +61,7 @@ public ICodeLoader loadDexFromInputStream(InputStream in, @Nullable String fileL
 
 	public ICodeLoader loadDexData(List<IDexData> list) {
 		List<DexReader> readers = list.stream()
-				.map(data -> loader.loadDexReader(data.getFileName(), data.getContent()))
+				.flatMap(data -> loader.loadDexReaders(data.getFileName(), data.getContent()).stream())
 				.collect(Collectors.toList());
 		return new DexLoadResult(readers, null);
 	}

jadx-plugins/jadx-dex-input/src/main/java/jadx/plugins/input/dex/DexReader.java

@@ -15,11 +15,11 @@ public class DexReader {
 	private final ByteBuffer buf;
 	private final DexHeader header;
 
-	public DexReader(int uniqId, String inputFileName, byte[] content) {
+	public DexReader(int uniqId, String inputFileName, byte[] content, int offset) {
 		this.uniqId = uniqId;
 		this.inputFileName = inputFileName;
 		this.buf = ByteBuffer.wrap(content);
-		this.header = new DexHeader(new SectionReader(this, 0));
+		this.header = new DexHeader(new SectionReader(this, offset));
 	}
 
 	public void visitClasses(Consumer<IClassData> consumer) {

jadx-plugins/jadx-dex-input/src/main/java/jadx/plugins/input/dex/sections/DexHeaderV41.java

@@ -0,0 +1,61 @@
+package jadx.plugins.input.dex.sections;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.jetbrains.annotations.Nullable;
+
+import static jadx.plugins.input.dex.utils.DataReader.readU4;
+
+public class DexHeaderV41 {
+
+	public static @Nullable DexHeaderV41 readIfPresent(byte[] content) {
+		int headerSize = readU4(content, 36);
+		if (headerSize < 120) {
+			return null;
+		}
+		int fileSize = readU4(content, 32);
+		int containerSize = readU4(content, 112);
+		int headerOffset = readU4(content, 116);
+		return new DexHeaderV41(fileSize, containerSize, headerOffset);
+	}
+
+	public static List<Integer> readSubDexOffsets(byte[] content, DexHeaderV41 header) {
+		int start = 0;
+		int end = header.getFileSize();
+		int limit = Math.min(header.getContainerSize(), content.length);
+		List<Integer> list = new ArrayList<>();
+		while (true) {
+			list.add(start);
+			start = end;
+			if (start >= limit) {
+				break;
+			}
+			int nextFileSize = readU4(content, start + 32);
+			end = start + nextFileSize;
+		}
+		return list;
+	}
+
+	private final int fileSize;
+	private final int containerSize;
+	private final int headerOffset;
+
+	public DexHeaderV41(int fileSize, int containerSize, int headerOffset) {
+		this.fileSize = fileSize;
+		this.containerSize = containerSize;
+		this.headerOffset = headerOffset;
+	}
+
+	public int getFileSize() {
+		return fileSize;
+	}
+
+	public int getContainerSize() {
+		return containerSize;
+	}
+
+	public int getHeaderOffset() {
+		return headerOffset;
+	}
+}

jadx-plugins/jadx-dex-input/src/main/java/jadx/plugins/input/dex/utils/DataReader.java

@@ -0,0 +1,12 @@
+package jadx.plugins.input.dex.utils;
+
+public class DataReader {
+
+	public static int readU4(byte[] data, int pos) {
+		byte b1 = data[pos++];
+		byte b2 = data[pos++];
+		byte b3 = data[pos++];
+		byte b4 = data[pos];
+		return (b4 & 0xFF) << 24 | (b3 & 0xFF) << 16 | (b2 & 0xFF) << 8 | b1 & 0xFF;
+	}
+}

jadx-plugins/jadx-dex-input/src/main/java/jadx/plugins/input/dex/utils/DexCheckSum.java

@@ -9,15 +9,15 @@
 
 public class DexCheckSum {
 
-	public static void verify(byte[] content, String fileName) {
+	public static void verify(String fileName, byte[] content, int offset) {
 		int len = content.length;
 		if (len < 12) {
 			throw new DexException("Dex file truncated, length: " + len + ", file: " + fileName);
 		}
-		int checksum = ByteBuffer.wrap(content, 8, 4).order(LITTLE_ENDIAN).getInt();
+		int checksum = ByteBuffer.wrap(content, offset + 8, 4).order(LITTLE_ENDIAN).getInt();
 		Adler32 adler32 = new Adler32();
 		adler32.update(content, 12, len - 12);
-		int fileChecksum = (int) (adler32.getValue());
+		int fileChecksum = (int) adler32.getValue();
 		if (checksum != fileChecksum) {
 			throw new DexException(String.format("Bad dex file checksum: 0x%08x, expected: 0x%08x, file: %s",
 					fileChecksum, checksum, fileName));