Fixed AesAudioDecrypt + do not copy buffer

Author: devgianlu

lib/src/main/java/xyz/gianlu/librespot/audio/cdn/CdnManager.java

@@ -241,8 +241,7 @@ private Streamer(@NotNull StreamId streamId, @NotNull SuperAudioFormat format, @
             available = new boolean[chunks];
             requested = new boolean[chunks];
 
-            buffer = new byte[chunks][CHUNK_SIZE];
-            buffer[chunks - 1] = new byte[size % CHUNK_SIZE];
+            buffer = new byte[chunks][];
 
             this.internalStream = new InternalStream(session.configuration().retryOnChunkError);
             writeChunk(firstChunk, 0, fromCache);
@@ -262,7 +261,8 @@ public void writeChunk(@NotNull byte[] chunk, int chunkIndex, boolean cached) th
 
             LOGGER.trace("Chunk {}/{} completed, cached: {}, stream: {}", chunkIndex, chunks, cached, describe());
 
-            audioDecrypt.decryptChunk(chunkIndex, chunk, buffer[chunkIndex]);
+            buffer[chunkIndex] = chunk;
+            audioDecrypt.decryptChunk(chunkIndex, chunk);
             internalStream.notifyChunkAvailable(chunkIndex);
         }
 

lib/src/main/java/xyz/gianlu/librespot/audio/decrypt/AesAudioDecrypt.java

@@ -1,5 +1,6 @@
 package xyz.gianlu.librespot.audio.decrypt;
 
+import org.jetbrains.annotations.NotNull;
 import xyz.gianlu.librespot.common.Utils;
 
 import javax.crypto.Cipher;
@@ -19,33 +20,35 @@
 public final class AesAudioDecrypt implements AudioDecrypt {
     private static final byte[] AUDIO_AES_IV = new byte[]{(byte) 0x72, (byte) 0xe0, (byte) 0x67, (byte) 0xfb, (byte) 0xdd, (byte) 0xcb, (byte) 0xcf, (byte) 0x77, (byte) 0xeb, (byte) 0xe8, (byte) 0xbc, (byte) 0x64, (byte) 0x3f, (byte) 0x63, (byte) 0x0d, (byte) 0x93};
     private final static BigInteger IV_INT = new BigInteger(1, AUDIO_AES_IV);
+    private static final BigInteger IV_DIFF = BigInteger.valueOf(0x100);
     private final SecretKeySpec secretKeySpec;
     private final Cipher cipher;
     private int decryptCount = 0;
     private long decryptTotalTime = 0;
 
     public AesAudioDecrypt(byte[] key) {
-        this.secretKeySpec = new SecretKeySpec(key, "AES");
         try {
+            this.secretKeySpec = new SecretKeySpec(key, "AES");
             this.cipher = Cipher.getInstance("AES/CTR/NoPadding");
-        } catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
-            throw new IllegalStateException(); // This should never happen
+        } catch (NoSuchAlgorithmException | NoSuchPaddingException ex) {
+            throw new IllegalStateException(ex); // This should never happen
         }
     }
 
     @Override
-    public synchronized void decryptChunk(int chunkIndex, byte[] in, byte[] out) throws IOException {
-        int pos = CHUNK_SIZE * chunkIndex;
-
+    public synchronized void decryptChunk(int chunkIndex, @NotNull byte[] buffer) throws IOException {
+        BigInteger iv = IV_INT.add(BigInteger.valueOf(CHUNK_SIZE * chunkIndex / 16));
         try {
             long start = System.nanoTime();
-            cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, new IvParameterSpec(Utils.toByteArray(IV_INT.add(BigInteger.valueOf(pos / 16)))));
+            for (int i = 0; i < buffer.length; i += 4096) {
+                cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, new IvParameterSpec(Utils.toByteArray(iv)));
+
+                int count = Math.min(4096, buffer.length - i);
+                int processed = cipher.doFinal(buffer, i, count, buffer, i);
+                if (count != processed)
+                    throw new IOException(String.format("Couldn't process all data, actual: %d, expected: %d", processed, count));
 
-            for (int i = 0; i < in.length; i += 4096) {
-                int endBytes = Math.min(i + 4096, in.length);
-                int count = cipher.doFinal(in, 0, endBytes, out, 0);
-                if (count != endBytes)
-                    throw new IOException(String.format("Couldn't process all data, actual: %d, expected: %d", count, endBytes));
+                iv = iv.add(IV_DIFF);
             }
 
             decryptTotalTime += System.nanoTime() - start;

lib/src/main/java/xyz/gianlu/librespot/audio/decrypt/AudioDecrypt.java

@@ -6,7 +6,7 @@
  * @author Gianlu
  */
 public interface AudioDecrypt {
-    void decryptChunk(int chunkIndex, byte[] in, byte[] out) throws IOException;
+    void decryptChunk(int chunkIndex, byte[] buffer) throws IOException;
 
     int decryptTimeMs();
 }

lib/src/main/java/xyz/gianlu/librespot/audio/decrypt/NoopAudioDecrypt.java

@@ -1,23 +1,11 @@
 package xyz.gianlu.librespot.audio.decrypt;
 
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
-
 /**
  * @author Gianlu
  */
 public final class NoopAudioDecrypt implements AudioDecrypt {
-    private final static Logger LOGGER = LogManager.getLogger(NoopAudioDecrypt.class);
-
     @Override
-    public void decryptChunk(int chunkIndex, byte[] in, byte[] out) {
-        int length = in.length;
-        if (in.length != out.length) {
-            length = Math.min(in.length, out.length);
-            LOGGER.warn("Buffers have different lengths! {index: {}, in: {}, out: {}}", chunkIndex, in.length, out.length);
-        }
-
-        System.arraycopy(in, 0, out, 0, length);
+    public void decryptChunk(int chunkIndex, byte[] buffer) {
     }
 
     @Override

lib/src/main/java/xyz/gianlu/librespot/audio/storage/AudioFileStreaming.java

@@ -24,8 +24,6 @@
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 
-import static xyz.gianlu.librespot.audio.storage.ChannelManager.CHUNK_SIZE;
-
 /**
  * @author Gianlu
  */
@@ -170,8 +168,7 @@ private class ChunksBuffer implements Closeable {
 
         ChunksBuffer(int size, int chunks) {
             this.size = size;
-            this.buffer = new byte[chunks][CHUNK_SIZE];
-            this.buffer[chunks - 1] = new byte[size % CHUNK_SIZE];
+            this.buffer = new byte[chunks][];
             this.available = new boolean[chunks];
             this.requested = new boolean[chunks];
             this.audioDecrypt = new AesAudioDecrypt(key);
@@ -184,7 +181,8 @@ void writeChunk(@NotNull byte[] chunk, int chunkIndex) throws IOException {
             if (chunk.length != buffer[chunkIndex].length)
                 throw new IllegalArgumentException(String.format("Buffer size mismatch, required: %d, received: %d, index: %d", buffer[chunkIndex].length, chunk.length, chunkIndex));
 
-            audioDecrypt.decryptChunk(chunkIndex, chunk, buffer[chunkIndex]);
+            buffer[chunkIndex] = chunk;
+            audioDecrypt.decryptChunk(chunkIndex, chunk);
             internalStream.notifyChunkAvailable(chunkIndex);
         }