Method rcv_continuation_frame

src/proxy/http2/Http2ConnectionState.cc:1011–1138

* [RFC 7540] 6.10 CONTINUATION * * NOTE: Logically, the CONTINUATION frames are part of the HEADERS frame. ([RFC *7540] 6.2 HEADERS) * */

 *
 */
Http2Error
Http2ConnectionState::rcv_continuation_frame(const Http2Frame &frame)
{
  const Http2StreamId stream_id      = frame.header().streamid;
  const uint32_t      payload_length = frame.header().length;

  Http2StreamDebug(this->session, stream_id, "Received CONTINUATION frame");

  if (!http2_is_client_streamid(stream_id)) {
    return Http2Error(Http2ErrorClass::HTTP2_ERROR_CLASS_CONNECTION, Http2ErrorCode::HTTP2_ERROR_PROTOCOL_ERROR,
                      "continuation bad client id");
  }

  if (payload_length == 0 && (frame.header().flags & HTTP2_FLAGS_HEADERS_END_HEADERS) == 0x0) {
    this->increment_received_empty_frame_count();
    if (configured_max_empty_frames_per_minute >= 0 &&
        this->get_received_empty_frame_count() > static_cast<uint32_t>(configured_max_empty_frames_per_minute)) {
      Metrics::Counter::increment(http2_rsb.max_empty_frames_per_minute_exceeded);
      Http2StreamDebug(this->session, stream_id, "Observed too many empty CONTINUATION frames: %u within the last minute",
                       this->get_received_empty_frame_count());
      return Http2Error(Http2ErrorClass::HTTP2_ERROR_CLASS_CONNECTION, Http2ErrorCode::HTTP2_ERROR_ENHANCE_YOUR_CALM,
                        "recv continuation too frequent empty frame");
    }
  }

  // Find opened stream
  // CONTINUATION frames MUST be associated with a stream.  If a
  // CONTINUATION frame is received whose stream identifier field is 0x0,
  // the recipient MUST respond with a connection error ([RFC 7540] Section
  // 5.4.1) of type PROTOCOL_ERROR.
  Http2Stream *stream = this->find_stream(stream_id);
  if (stream == nullptr) {
    if (this->is_valid_streamid(stream_id)) {
      return Http2Error(Http2ErrorClass::HTTP2_ERROR_CLASS_CONNECTION, Http2ErrorCode::HTTP2_ERROR_STREAM_CLOSED,
                        "continuation stream freed with valid id");
    } else {
      return Http2Error(Http2ErrorClass::HTTP2_ERROR_CLASS_CONNECTION, Http2ErrorCode::HTTP2_ERROR_PROTOCOL_ERROR,
                        "continuation stream freed with invalid id");
    }
  } else {
    switch (stream->get_state()) {
    case Http2StreamState::HTTP2_STREAM_STATE_HALF_CLOSED_REMOTE:
      return Http2Error(Http2ErrorClass::HTTP2_ERROR_CLASS_CONNECTION, Http2ErrorCode::HTTP2_ERROR_STREAM_CLOSED,
                        "continuation half close remote");
    case Http2StreamState::HTTP2_STREAM_STATE_IDLE:
      break;
    default:
      return Http2Error(Http2ErrorClass::HTTP2_ERROR_CLASS_CONNECTION, Http2ErrorCode::HTTP2_ERROR_PROTOCOL_ERROR,
                        "continuation bad state");
    }
  }

  // Update CONTINUATION frame count per minute.
  this->increment_received_continuation_frame_count();
  // Close this connection if its CONTINUATION frame count exceeds a limit.
  if (configured_max_continuation_frames_per_minute != 0 &&
      this->get_received_continuation_frame_count() > static_cast<uint32_t>(configured_max_continuation_frames_per_minute)) {
    Metrics::Counter::increment(http2_rsb.max_continuation_frames_per_minute_exceeded);