HttpObjectDecoder throws TooLongFrameException when it should not

[angxu]

Netty version: 4.0.25.Final

It seems the HttpObjectDecoder does not behave correctly when receiving large HTTP header whose data is across multiple ByteBufs. Specifically, the following method in HeaderParser does not reset its size or update buffer's readerIndex when it returns null. So the next time it's called with an accumulated buffer that contains the previous one, the size of the previous buffer will be counted twice.

Is this a bug or do I miss anything here?

public AppendableCharSequence parse(ByteBuf buffer) {
  seq.reset();
  int i = buffer.forEachByte(this);
  if (i == -1) {
    return null;
  }
  buffer.readerIndex(i + 1);
  return seq;
}

[angxu]

I wrote an unit test that can reproduce this bug against HEAD.

    @Test
    public void testMaxHeaderSize() {
      final int maxHeaderSize = 8192;

      final EmbeddedChannel ch = new EmbeddedChannel(new HttpResponseDecoder(4096, maxHeaderSize, maxHeaderSize));
      final char[] bytes = new char[maxHeaderSize / 2];
      Arrays.fill(bytes, 'a');

      try
      {
        ch.writeInbound(Unpooled.copiedBuffer("HTTP/1.1 200 OK\r\n", CharsetUtil.US_ASCII));
        ch.writeInbound(Unpooled.copiedBuffer("X-A-Large-Header: ", CharsetUtil.US_ASCII));
        ch.writeInbound(Unpooled.copiedBuffer(bytes, CharsetUtil.US_ASCII)); // write 4096 bytes
        ch.writeInbound(Unpooled.copiedBuffer("\r\n\r\n", CharsetUtil.US_ASCII));
        // uncomment the following line with above 3 lines commented out, and the test shall pass.
        //ch.writeInbound(Unpooled.copiedBuffer("X-A-Large-Header: " + bytes + "\r\n\r\n", CharsetUtil.US_ASCII));
      }
      catch (Exception ex)
      {
        //pass through so that we can check DecoderResult;
      }

      HttpResponse res = (HttpResponse) ch.readInbound();
      assertTrue(res.getDecoderResult().isSuccess());
    }

Can someone please take a look? This is blocking us from adopting Netty 4 - which we are eagerly looking forward to because it looks all great otherwise.

Thanks!

[trustin]

@angxu #3460 should fix this problem.