From dc1b511fcf6d5f902c7ca475cbaa7fdd026c62f1 Mon Sep 17 00:00:00 2001
From: Norman Maurer <norman_maurer@apple.com>
Date: Tue, 4 Sep 2018 19:13:56 +0200
Subject: [PATCH] Correctly reset offset when fail lazy because of too long
 frame. (#8257)

Motivation:

We need to reset the offset to 0 when we fail lazy because of a too long frame.

Modifications:

- Reset offset
- Add testcase

Result:

Fixes https://github.com/netty/netty/issues/8256.
---
 .../handler/codec/LineBasedFrameDecoder.java  |  2 ++
 .../codec/LineBasedFrameDecoderTest.java      | 23 +++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/codec/src/main/java/io/netty/handler/codec/LineBasedFrameDecoder.java b/codec/src/main/java/io/netty/handler/codec/LineBasedFrameDecoder.java
index 305981b762..58f2e85f04 100644
--- a/codec/src/main/java/io/netty/handler/codec/LineBasedFrameDecoder.java
+++ b/codec/src/main/java/io/netty/handler/codec/LineBasedFrameDecoder.java
@@ -137,6 +137,8 @@ public class LineBasedFrameDecoder extends ByteToMessageDecoder {
             } else {
                 discardedBytes += buffer.readableBytes();
                 buffer.readerIndex(buffer.writerIndex());
+                // We skip everything in the buffer, we need to set the offset to 0 again.
+                offset = 0;
             }
             return null;
         }
diff --git a/codec/src/test/java/io/netty/handler/codec/LineBasedFrameDecoderTest.java b/codec/src/test/java/io/netty/handler/codec/LineBasedFrameDecoderTest.java
index b68c38bbbe..9edd178fa2 100644
--- a/codec/src/test/java/io/netty/handler/codec/LineBasedFrameDecoderTest.java
+++ b/codec/src/test/java/io/netty/handler/codec/LineBasedFrameDecoderTest.java
@@ -185,4 +185,27 @@ public class LineBasedFrameDecoderTest {
         buf.release();
         buf2.release();
     }
+
+    @Test
+    public void testNotFailFast() throws Exception {
+        EmbeddedChannel ch = new EmbeddedChannel(new LineBasedFrameDecoder(2, false, false));
+        assertFalse(ch.writeInbound(wrappedBuffer(new byte[] { 0, 1, 2 })));
+        assertFalse(ch.writeInbound(wrappedBuffer(new byte[]{ 3, 4 })));
+        try {
+            ch.writeInbound(wrappedBuffer(new byte[] { '\n' }));
+            fail();
+        } catch (TooLongFrameException expected) {
+            // Expected once we received a full frame.
+        }
+        assertFalse(ch.writeInbound(wrappedBuffer(new byte[] { '5' })));
+        assertTrue(ch.writeInbound(wrappedBuffer(new byte[] { '\n' })));
+
+        ByteBuf expected = wrappedBuffer(new byte[] { '5', '\n' });
+        ByteBuf buffer = ch.readInbound();
+        assertEquals(expected, buffer);
+        expected.release();
+        buffer.release();
+
+        assertFalse(ch.finish());
+    }
 }