Fix NPE problems

Motivation:

Now Netty has a few problems with null values.

Modifications:

- Check File in DiskFileUpload.toString().
If File is null we will get NPE when calling toString() method.
- Check Result<String> in MqttDecoder.decodeConnectionPayload(...).
- Check Unsafe before calling unsafe.getClass() in PlatformDependent0 static block.
- Removed unnecessary null check in WebSocket08FrameEncoder.encode(...).
Because msg.content() can not return null.
- Removed unnecessary null checks in ConcurrentHashMapV8.removeTreeNode(TreeNode<K,V>).
- Removed unnecessary null check in OioDatagramChannel.doReadMessages(List<Object>).
Because tmpPacket.getSocketAddress() always returns new SocketAddress instance.
- Removed unnecessary null check in OioServerSocketChannel.doReadMessages(List<Object>).
Because socket.accept() always returns new Socket instance.
- Pass Unpooled.buffer(0) instead of null inside CloseWebSocketFrame(boolean, int) constructor.
If we will pass null we will get NPE in super class constructor.
- Added throw new IllegalStateException in GlobalEventExecutor.awaitInactivity(long, TimeUnit) if it will be called before GlobalEventExecutor.execute(Runnable).
Because now we will get NPE. IllegalStateException will be better in this case.
- Fixed null check in OpenSslServerContext.setTicketKeys(byte[]).
Now we throw new NPE if byte[] is not null.

Result:

Added new null checks when it is necessary, removed unnecessary null checks and fixed some NPE problems.

codec-http/src/main/java/io/netty/handler/codec/http/multipart/DiskFileUpload.java

@@ -133,7 +133,7 @@ public class DiskFileUpload extends AbstractDiskHttpData implements FileUpload {
                 HttpHeaders.Names.CONTENT_LENGTH + ": " + length() + "\r\n" +
                 "Completed: " + isCompleted() +
                 "\r\nIsInMemory: " + isInMemory() + "\r\nRealFile: " +
-                file.getAbsolutePath() + " DefaultDeleteAfter: " +
+                (file != null ? file.getAbsolutePath() : "null") + " DefaultDeleteAfter: " +
                 deleteOnExitTemporaryFile;
     }
 

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/CloseWebSocketFrame.java

@@ -54,7 +54,7 @@ public class CloseWebSocketFrame extends WebSocketFrame {
      *            reserved bits used for protocol extensions
      */
     public CloseWebSocketFrame(boolean finalFragment, int rsv) {
-        this(finalFragment, rsv, null);
+        this(finalFragment, rsv, Unpooled.buffer(0));
     }
 
     /**

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocket08FrameEncoder.java

@@ -54,7 +54,6 @@
 package io.netty.handler.codec.http.websocketx;
 
 import io.netty.buffer.ByteBuf;
-import io.netty.buffer.Unpooled;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.MessageToMessageEncoder;
 import io.netty.handler.codec.TooLongFrameException;
@@ -96,14 +95,9 @@ public class WebSocket08FrameEncoder extends MessageToMessageEncoder<WebSocketFr
 
     @Override
     protected void encode(ChannelHandlerContext ctx, WebSocketFrame msg, List<Object> out) throws Exception {
-
+        final ByteBuf data = msg.content();
         byte[] mask;
 
-        ByteBuf data = msg.content();
-        if (data == null) {
-            data = Unpooled.EMPTY_BUFFER;
-        }
-
         byte opcode;
         if (msg instanceof TextWebSocketFrame) {
             opcode = OPCODE_TEXT;

common/src/main/java/io/netty/util/concurrent/GlobalEventExecutor.java

@@ -203,10 +203,11 @@ public final class GlobalEventExecutor extends AbstractEventExecutor {
             throw new NullPointerException("unit");
         }
 
-        Thread thread = this.thread;
-        if (thread != null) {
-            thread.join(unit.toMillis(timeout));
+        final Thread thread = this.thread;
+        if (thread == null) {
+            throw new IllegalStateException("thread was not started");
         }
+        thread.join(unit.toMillis(timeout));
         return !thread.isAlive();
     }
 

common/src/main/java/io/netty/util/internal/PlatformDependent0.java

@@ -80,16 +80,17 @@ final class PlatformDependent0 {
                 Field unsafeField = Unsafe.class.getDeclaredField("theUnsafe");
                 unsafeField.setAccessible(true);
                 unsafe = (Unsafe) unsafeField.get(null);
-                logger.debug("sun.misc.Unsafe.theUnsafe: {}", unsafe != null? "available" : "unavailable");
+                logger.debug("sun.misc.Unsafe.theUnsafe: {}", unsafe != null ? "available" : "unavailable");
 
                 // Ensure the unsafe supports all necessary methods to work around the mistake in the latest OpenJDK.
                 // https://github.com/netty/netty/issues/1061
                 // http://www.mail-archive.com/jdk6-dev@openjdk.java.net/msg00698.html
                 try {
-                    unsafe.getClass().getDeclaredMethod(
-                            "copyMemory", Object.class, long.class, Object.class, long.class, long.class);
-
-                    logger.debug("sun.misc.Unsafe.copyMemory: available");
+                    if (unsafe != null) {
+                        unsafe.getClass().getDeclaredMethod(
+                                "copyMemory", Object.class, long.class, Object.class, long.class, long.class);
+                        logger.debug("sun.misc.Unsafe.copyMemory: available");
+                    }
                 } catch (NoSuchMethodError t) {
                     logger.debug("sun.misc.Unsafe.copyMemory: unavailable");
                     throw t;

common/src/main/java/io/netty/util/internal/chmv8/ConcurrentHashMapV8.java

@@ -2830,14 +2830,14 @@ public class ConcurrentHashMapV8<K,V>
                             else
                                 sp.right = p;
                         }
-                        if ((s.right = pr) != null)
-                            pr.parent = s;
+                        s.right = pr;
+                        pr.parent = s;
                     }
                     p.left = null;
+                    s.left = pl;
+                    pl.parent = s;
                     if ((p.right = sr) != null)
                         sr.parent = p;
-                    if ((s.left = pl) != null)
-                        pl.parent = s;
                     if ((s.parent = pp) == null)
                         r = s;
                     else if (p == pp.left)

handler/src/main/java/io/netty/handler/ssl/OpenSslServerContext.java

@@ -322,7 +322,7 @@ public final class OpenSslServerContext extends SslContext {
      * Sets the SSL session ticket keys of this context.
      */
     public void setTicketKeys(byte[] keys) {
-        if (keys != null) {
+        if (keys == null) {
             throw new NullPointerException("keys");
         }
         SSLContext.setSessionTicketKeys(ctx, keys);

transport/src/main/java/io/netty/channel/socket/oio/OioDatagramChannel.java

@@ -209,9 +209,6 @@ public class OioDatagramChannel extends AbstractOioMessageChannel
             socket.receive(tmpPacket);
 
             InetSocketAddress remoteAddr = (InetSocketAddress) tmpPacket.getSocketAddress();
-            if (remoteAddr == null) {
-                remoteAddr = remoteAddress();
-            }
 
             int readBytes = tmpPacket.getLength();
             allocHandle.record(readBytes);

transport/src/main/java/io/netty/channel/socket/oio/OioServerSocketChannel.java

@@ -153,18 +153,14 @@ public class OioServerSocketChannel extends AbstractOioMessageChannel
         try {
             Socket s = socket.accept();
             try {
-                if (s != null) {
-                    buf.add(new OioSocketChannel(this, s));
-                    return 1;
-                }
+                buf.add(new OioSocketChannel(this, s));
+                return 1;
             } catch (Throwable t) {
                 logger.warn("Failed to create a new channel from an accepted socket.", t);
-                if (s != null) {
-                    try {
-                        s.close();
-                    } catch (Throwable t2) {
-                        logger.warn("Failed to close a socket.", t2);
-                    }
+                try {
+                    s.close();
+                } catch (Throwable t2) {
+                    logger.warn("Failed to close a socket.", t2);
                 }
             }
         } catch (SocketTimeoutException e) {