Looping to bnc@ , who made some latest changes in spdy_session.cc.

Almost similar issue : https://bugs.chromium.org/p/chromium/issues/detail?id=666007, but not sure its the dupe of this.

Thanks! This does not seem to be the same issue as #666007. This issue is triggered by large frame size and #666007 seems to be about some particular incoming header format (I guess).

I am no expert in this part of the code but the internal version of spdy_session.cc has changed and doesn't even have the failing function from your log message.

Maybe updating to a newer version of the Cronet lib (if it tracks exactly the internal implementation) might fix it for you.

That was my bad; I got the function name wrong. The failing function name is net::SpdyFramer::ValidateFrameHeader.

I tried this on a newer version 56.0.2914.0 and it did not quite help.

Here's a complete stack trace when the problem occurs. I hope this would help:

* thread #5: tid = 0x12fc5d, 0x0000000111ce3744 Cronet`base::debug::BreakDebugger() + 20 at debugger_posix.cc:262, name = 'Chrome Network IO Thread', stop reason = EXC_BREAKPOINT (code=EXC_I386_BPT, subcode=0x0)
  * frame #0: 0x0000000111ce3744 Cronet`base::debug::BreakDebugger() + 20 at debugger_posix.cc:262
    frame #1: 0x0000000111d51658 Cronet`logging::LogMessage::~LogMessage(this=0x00007000005a9bb0) + 4296 at logging.cc:748
    frame #2: 0x0000000111d4e385 Cronet`logging::LogMessage::~LogMessage(this=0x00007000005a9bb0) + 21 at logging.cc:528
    frame #3: 0x00000001129fcb88 Cronet`net::MapFramerErrorToNetError(err=SPDY_OVERSIZED_PAYLOAD) + 424 at spdy_session.cc:378
    frame #4: 0x0000000112a1ce00 Cronet`net::SpdySession::OnError(this=0x00007fbd5c01ec00, error_code=SPDY_OVERSIZED_PAYLOAD) + 272 at spdy_session.cc:1930
    frame #5: 0x00000001129618cd Cronet`net::BufferedSpdyFramer::OnError(this=0x00007fbd5b129e40, spdy_framer=0x00007fbd5b129e48) + 301 at buffered_spdy_framer.cc:45
    frame #6: 0x00000001129ae57a Cronet`net::SpdyFramer::set_error(this=0x00007fbd5b129e48, error=SPDY_OVERSIZED_PAYLOAD) + 666 at spdy_framer.cc:500
    frame #7: 0x00000001129b7f4b Cronet`net::SpdyFramer::ValidateFrameHeader(this=0x00007fbd5b129e48, is_control_frame=false, frame_type_field=0, payload_length_field=32768) + 2331 at spdy_framer.cc:849
    frame #8: 0x00000001129b08fd Cronet`net::SpdyFramer::ProcessCommonHeader(this=0x00007fbd5b129e48, data="", len=8144) + 3997 at spdy_framer.cc:962
    frame #9: 0x00000001129af108 Cronet`net::SpdyFramer::ProcessInput(this=0x00007fbd5b129e48, data="", len=8153) + 1704 at spdy_framer.cc:639
    frame #10: 0x00000001129640a4 Cronet`net::BufferedSpdyFramer::ProcessInput(this=0x00007fbd5b129e40, data="", len=8192) + 52 at buffered_spdy_framer.cc:232
    frame #11: 0x0000000112a1483c Cronet`net::SpdySession::DoReadComplete(this=0x00007fbd5c01ec00, result=8192) + 2220 at spdy_session.cc:1345
    frame #12: 0x0000000112a13889 Cronet`net::SpdySession::DoReadLoop(this=0x00007fbd5c01ec00, expected_read_state=READ_STATE_DO_READ_COMPLETE, result=8192) + 713 at spdy_session.cc:1271
    frame #13: 0x0000000112a0604e Cronet`net::SpdySession::PumpReadLoop(this=0x00007fbd5c01ec00, expected_read_state=READ_STATE_DO_READ_COMPLETE, result=8192) + 238 at spdy_session.cc:1246
    frame #14: 0x0000000112a4495b Cronet`void base::internal::FunctorTraits<void (net::SpdySession::*)(net::SpdySession::ReadState, int), void>::Invoke<base::WeakPtr<net::SpdySession> const&, net::SpdySession::ReadState const&, int>(method=60 5f a0 12 01 00 00 00 00 00 00 00 00 00 00 00, receiver_ptr=0x00007fbd5b1304d0, args=0x00007fbd5b1304e0, args=0x00007000005ae4fc)(net::SpdySession::ReadState, int), base::WeakPtr<net::SpdySession> const&&&, net::SpdySession::ReadState const&&&, int&&) + 171 at bind_internal.h:214
    frame #15: 0x0000000112a44855 Cronet`void base::internal::InvokeHelper<true, void>::MakeItSo<void (functor=0x00007fbd5b1304c0, weak_ptr=0x00007fbd5b1304d0, args=0x00007fbd5b1304e0, args=0x00007000005ae4fc)(net::SpdySession::ReadState, int), base::WeakPtr<net::SpdySession> const&, net::SpdySession::ReadState const&, int>(void (net::SpdySession::* const&&&)(net::SpdySession::ReadState, int), base::WeakPtr<net::SpdySession> const&&&, net::SpdySession::ReadState const&&&, int&&) + 133 at bind_internal.h:305
    frame #16: 0x0000000112a447c9 Cronet`void base::internal::Invoker<base::internal::BindState<void (net::SpdySession::*)(net::SpdySession::ReadState, int), base::WeakPtr<net::SpdySession>, net::SpdySession::ReadState>, void (int)>::RunImpl<void (functor=0x00007fbd5b1304c0, bound=0x00007fbd5b1304d0, (null)=IndexSequence<0, 1> @ 0x00007000005ae468, unbound_args=0x00007000005ae4fc)(net::SpdySession::ReadState, int), std::__1::tuple<base::WeakPtr<net::SpdySession>, net::SpdySession::ReadState> const&, 0ul, 1ul>(void (net::SpdySession::* const&&&)(net::SpdySession::ReadState, int), std::__1::tuple<base::WeakPtr<net::SpdySession>, net::SpdySession::ReadState> const&&&, base::IndexSequence<0ul, 1ul>, int&&) + 121 at bind_internal.h:361
    frame #17: 0x0000000112a446e4 Cronet`base::internal::Invoker<base::internal::BindState<void (net::SpdySession::*)(net::SpdySession::ReadState, int), base::WeakPtr<net::SpdySession>, net::SpdySession::ReadState>, void (int)>::Run(base=0x00007fbd5b1304a0, unbound_args=0x00007000005ae4fc) + 68 at bind_internal.h:339
    frame #18: 0x0000000111c04faa Cronet`base::internal::RunMixin<base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> >::Run(this=0x00007000005ae538, args=8192) const + 74 at callback.h:64
    frame #19: 0x000000011213b64e Cronet`net::SSLClientSocketImpl::DoReadCallback(this=0x00007fbd59d18870, rv=8192) + 110 at ssl_client_socket_impl.cc:1012
    frame #20: 0x000000011213aacd Cronet`net::SSLClientSocketImpl::RetryAllOperations(this=0x00007fbd59d18870) + 189 at ssl_client_socket_impl.cc:1501
    frame #21: 0x000000011213aa05 Cronet`net::SSLClientSocketImpl::OnReadReady(this=0x00007fbd59d18870) + 21 at ssl_client_socket_impl.cc:839
    frame #22: 0x000000011212cbe6 Cronet`net::SocketBIOAdapter::OnSocketReadComplete(this=0x00007fbd59d1f120, result=17408) + 262 at socket_bio_adapter.cc:136
    frame #23: 0x000000011212f219 Cronet`void base::internal::FunctorTraits<void (net::SocketBIOAdapter::*)(int), void>::Invoke<base::WeakPtr<net::SocketBIOAdapter> const&, int>(method=e0 ca 12 12 01 00 00 00 00 00 00 00 00 00 00 00, receiver_ptr=0x00007fbd59d19c10, args=0x00007000005ae8cc)(int), base::WeakPtr<net::SocketBIOAdapter> const&&&, int&&) + 153 at bind_internal.h:214
    frame #24: 0x000000011212f125 Cronet`void base::internal::InvokeHelper<true, void>::MakeItSo<void (functor=0x00007fbd59d19c00, weak_ptr=0x00007fbd59d19c10, args=0x00007000005ae8cc)(int), base::WeakPtr<net::SocketBIOAdapter> const&, int>(void (net::SocketBIOAdapter::* const&&&)(int), base::WeakPtr<net::SocketBIOAdapter> const&&&, int&&) + 117 at bind_internal.h:305
    frame #25: 0x000000011212f0a8 Cronet`void base::internal::Invoker<base::internal::BindState<void (net::SocketBIOAdapter::*)(int), base::WeakPtr<net::SocketBIOAdapter> >, void (int)>::RunImpl<void (functor=0x00007fbd59d19c00, bound=0x00007fbd59d19c10, (null)=IndexSequence<0> @ 0x00007000005ae840, unbound_args=0x00007000005ae8cc)(int), std::__1::tuple<base::WeakPtr<net::SocketBIOAdapter> > const&, 0ul>(void (net::SocketBIOAdapter::* const&&&)(int), std::__1::tuple<base::WeakPtr<net::SocketBIOAdapter> > const&&&, base::IndexSequence<0ul>, int&&) + 88 at bind_internal.h:361
    frame #26: 0x000000011212eff4 Cronet`base::internal::Invoker<base::internal::BindState<void (net::SocketBIOAdapter::*)(int), base::WeakPtr<net::SocketBIOAdapter> >, void (int)>::Run(base=0x00007fbd59d19be0, unbound_args=0x00007000005ae8cc) + 68 at bind_internal.h:339
    frame #27: 0x0000000111c04faa Cronet`base::internal::RunMixin<base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> >::Run(this=0x00007fbd5b12c338, args=17408) const + 74 at callback.h:64
    frame #28: 0x0000000112929e58 Cronet`net::TCPClientSocket::DidCompleteReadWrite(this=0x00007fbd59e146d0, callback=0x00007fbd5b12c338, result=17408), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int) + 120 at tcp_client_socket.cc:374
    frame #29: 0x000000011292961b Cronet`net::TCPClientSocket::DidCompleteRead(this=0x00007fbd59e146d0, callback=0x00007fbd5b12c338, result=17408), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int) + 75 at tcp_client_socket.cc:357
    frame #30: 0x000000011292b157 Cronet`void base::internal::FunctorTraits<void (net::TCPClientSocket::*)(base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), void>::Invoke<net::TCPClientSocket*, base::Callback<void (method=d0 95 92 12 01 00 00 00 00 00 00 00 00 00 00 00, receiver_ptr=0x00007000005aeaa8, args=0x00007fbd5b12c338, args=0x00007000005aeb5c), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int>(void (net::TCPClientSocket::*)(base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), net::TCPClientSocket*&&, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&&&, int&&) + 167 at bind_internal.h:214
    frame #31: 0x000000011292b05a Cronet`void base::internal::InvokeHelper<false, void>::MakeItSo<void (functor=0x00007fbd5b12c320, args=0x00007000005aeaa8, args=0x00007fbd5b12c338, args=0x00007000005aeb5c)(base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), net::TCPClientSocket*, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int>(void (net::TCPClientSocket::* const&&&)(base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), net::TCPClientSocket*&&, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&&&, int&&) + 122 at bind_internal.h:285
    frame #32: 0x000000011292afd9 Cronet`void base::internal::Invoker<base::internal::BindState<void (net::TCPClientSocket::*)(base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), base::internal::UnretainedWrapper<net::TCPClientSocket>, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> >, void (int)>::RunImpl<void (functor=0x00007fbd5b12c320, bound=0x00007fbd5b12c330, (null)=IndexSequence<0, 1> @ 0x00007000005aeac8, unbound_args=0x00007000005aeb5c)(base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), std::__1::tuple<base::internal::UnretainedWrapper<net::TCPClientSocket>, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> > const&, 0ul, 1ul>(void (net::TCPClientSocket::* const&&&)(base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), std::__1::tuple<base::internal::UnretainedWrapper<net::TCPClientSocket>, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> > const&&&, base::IndexSequence<0ul, 1ul>, int&&) + 121 at bind_internal.h:361
    frame #33: 0x000000011292aef4 Cronet`base::internal::Invoker<base::internal::BindState<void (net::TCPClientSocket::*)(base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), base::internal::UnretainedWrapper<net::TCPClientSocket>, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> >, void (int)>::Run(base=0x00007fbd5b12c300, unbound_args=0x00007000005aeb5c) + 68 at bind_internal.h:339
    frame #34: 0x0000000111c04faa Cronet`base::internal::RunMixin<base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> >::Run(this=0x00007fbd5b12f900, args=17408) const + 74 at callback.h:64
    frame #35: 0x000000011292ee24 Cronet`net::TCPSocketPosix::ReadCompleted(this=0x00007fbd59e14f40, buf=0x00007fbd5b12f8f8, callback=0x00007fbd5b12f900, rv=17408), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int) + 292 at tcp_socket_posix.cc:591
    frame #36: 0x000000011293359a Cronet`void base::internal::FunctorTraits<void (net::TCPSocketPosix::*)(scoped_refptr<net::IOBuffer> const&, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), void>::Invoke<net::TCPSocketPosix*, scoped_refptr<net::IOBuffer> const&, base::Callback<void (method=00 ed 92 12 01 00 00 00 00 00 00 00 00 00 00 00, receiver_ptr=0x00007000005aee30, args=0x00007fbd5b12f8f8, args=0x00007fbd5b12f900, args=0x00007000005aeeec), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int>(void (net::TCPSocketPosix::*)(scoped_refptr<net::IOBuffer> const&, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), net::TCPSocketPosix*&&, scoped_refptr<net::IOBuffer> const&&&, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&&&, int&&) + 186 at bind_internal.h:214
    frame #37: 0x000000011293342a Cronet`void base::internal::InvokeHelper<false, void>::MakeItSo<void (functor=0x00007fbd5b12f8e0, args=0x00007000005aee30, args=0x00007fbd5b12f8f8, args=0x00007fbd5b12f900, args=0x00007000005aeeec)(scoped_refptr<net::IOBuffer> const&, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), net::TCPSocketPosix*, scoped_refptr<net::IOBuffer> const&, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int>(void (net::TCPSocketPosix::* const&&&)(scoped_refptr<net::IOBuffer> const&, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), net::TCPSocketPosix*&&, scoped_refptr<net::IOBuffer> const&&&, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&&&, int&&) + 138 at bind_internal.h:285
    frame #38: 0x000000011293339a Cronet`void base::internal::Invoker<base::internal::BindState<void (net::TCPSocketPosix::*)(scoped_refptr<net::IOBuffer> const&, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), base::internal::UnretainedWrapper<net::TCPSocketPosix>, scoped_refptr<net::IOBuffer>, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> >, void (int)>::RunImpl<void (functor=0x00007fbd5b12f8e0, bound=0x00007fbd5b12f8f0, (null)=IndexSequence<0, 1, 2> @ 0x00007000005aee50, unbound_args=0x00007000005aeeec)(scoped_refptr<net::IOBuffer> const&, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), std::__1::tuple<base::internal::UnretainedWrapper<net::TCPSocketPosix>, scoped_refptr<net::IOBuffer>, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> > const&, 0ul, 1ul, 2ul>(void (net::TCPSocketPosix::* const&&&)(scoped_refptr<net::IOBuffer> const&, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), std::__1::tuple<base::internal::UnretainedWrapper<net::TCPSocketPosix>, scoped_refptr<net::IOBuffer>, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> > const&&&, base::IndexSequence<0ul, 1ul, 2ul>, int&&) + 154 at bind_internal.h:361
    frame #39: 0x0000000112933284 Cronet`base::internal::Invoker<base::internal::BindState<void (net::TCPSocketPosix::*)(scoped_refptr<net::IOBuffer> const&, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> const&, int), base::internal::UnretainedWrapper<net::TCPSocketPosix>, scoped_refptr<net::IOBuffer>, base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> >, void (int)>::Run(base=0x00007fbd5b12f8c0, unbound_args=0x00007000005aeeec) + 68 at bind_internal.h:339
    frame #40: 0x0000000111c04faa Cronet`base::internal::RunMixin<base::Callback<void (int), (base::internal::CopyMode)1, (base::internal::RepeatMode)1> >::Run(this=0x00007000005aef20, args=17408) const + 74 at callback.h:64
    frame #41: 0x00000001129038fa Cronet`net::SocketPosix::ReadCompleted(this=0x00007fbd59e14fa0) + 410 at socket_posix.cc:460
    frame #42: 0x000000011290343f Cronet`net::SocketPosix::OnFileCanReadWithoutBlocking(this=0x00007fbd59e14fa0, fd=15) + 591 at socket_posix.cc:377
    frame #43: 0x0000000111d85dfa Cronet`base::MessagePumpIOSForIO::FileDescriptorWatcher::OnFileCanReadWithoutBlocking(this=0x00007fbd59e14ff8, fd=15, pump=0x00007fbd5b123fd0) + 282 at message_pump_io_ios.cc:54
    frame #44: 0x0000000111d86d8c Cronet`base::MessagePumpIOSForIO::HandleFdIOEvent(fdref=0x00007fbd5b12d710, callback_types=1, context=0x00007fbd59e14ff8) + 748 at message_pump_io_ios.cc:178
    frame #45: 0x00000001078b7364 CoreFoundation`__CFFileDescriptorPerform + 564
    frame #46: 0x000000010781b301 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    frame #47: 0x00000001078111a7 CoreFoundation`__CFRunLoopDoSources0 + 423
    frame #48: 0x00000001078106e3 CoreFoundation`__CFRunLoopRun + 867
    frame #49: 0x00000001078100f8 CoreFoundation`CFRunLoopRunSpecific + 488
    frame #50: 0x0000000106f50a31 Foundation`-[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 267
    frame #51: 0x000000011200c9e9 Cronet`base::MessagePumpNSRunLoop::DoRun(this=0x00007fbd5b123fd0, delegate=0x00007fbd5b001920) + 137 at message_pump_mac.mm:580
    frame #52: 0x000000011200bd5a Cronet`base::MessagePumpCFRunLoopBase::Run(this=0x00007fbd5b123fd0, delegate=0x00007fbd5b001920) + 122 at message_pump_mac.mm:210
    frame #53: 0x0000000111d72385 Cronet`base::MessageLoop::RunHandler(this=0x00007fbd5b001920) + 645 at message_loop.cc:378
    frame #54: 0x0000000111e12bc4 Cronet`base::RunLoop::Run(this=0x00007000005b1118) + 68 at run_loop.cc:35
    frame #55: 0x0000000111ee055c Cronet`base::Thread::Run(this=0x00007fbd5b001680, run_loop=0x00007000005b1118) + 428 at thread.cc:245
    frame #56: 0x0000000111ee1788 Cronet`base::Thread::ThreadMain(this=0x00007fbd5b001680) + 3512 at thread.cc:333
    frame #57: 0x0000000111ebcfa7 Cronet`base::(anonymous namespace)::ThreadFunc(params=0x00007fbd5b001300) + 679 at platform_thread_posix.cc:71
    frame #58: 0x000000010a50699d libsystem_pthread.dylib`_pthread_body + 131
    frame #59: 0x000000010a50691a libsystem_pthread.dylib`_pthread_start + 168
    frame #60: 0x000000010a504351 libsystem_pthread.dylib`thread_start + 13

Reading through the code of the failing function it is indeed a check for the size of the packet:

  if (protocol_version_ == HTTP2 &&
      payload_length_field > recv_frame_size_limit_) {
    set_error(SPDY_OVERSIZED_PAYLOAD);
  }

where recv_frame_size_limit_ is initialized as (1 << 14) so no surprise the check fails for you.

Digging further it seems there is a function called set_recv_frame_size_limit which seems to be public and can change this limit arbitrarily. Have you tried calling it?

Ahh thank you for pointing that out. No we are unable to call that func since we are using Cronet's 'cronet_c_for_grpc' api and do not have access to it. I guess right now I will have to treat it as a hard written value. Many thanks!

Actually looping in bnc@. This is affecting GRPC usage of cronet bidirectional stream over H2 on iOS. I wonder whether or not it also affects Android implementation?

Removing the enterprise label and myself from this bug as I think I can't contribute to this discussion any further and it is not related tot he enterprise components of Chrome either.

We'll discuss this issue in Cronet triage. I'm also removing proxy label

Sorry for the late response.

The HTTP/2 specification says that frames of length greater than 2^14 (16,384) MUST NOT be sent unless the receiver has set a larger value for SETTINGS_MAX_FRAME_SIZE.  The receiver in this case is Cronet, and Cronet currently does not set a value for SETTINGS_MAX_FRAME_SIZE (this would be sent by Cronet in a SETTINGS frame).  It sounds like the server you are using does not conform to the specification.  I believe this is working as intended, so I'm closing the issue.

If you believe you would benefit from a knob to increase maximum frame size, please feel free to file another issue against Cronet, that would be a feature request.  It is certainly possible to add such a setting to the API, and plumb it through, and make Cronet send a larger value in the initial SETTINGS frame that it is already sending anyway.  There never was a need for this, since the dozen or so bytes frame header is already negligible compared to a 16 kB payload, but it is certainly technically possible if there is a need for it.

Forgot the link to the relevant part in the spec: http://httpwg.org/specs/rfc7540.html#FrameHeader.

Good to know that Bence. Thank you!