Method processHeaders

internal/http2/transport.go:2415–2471

(f *MetaHeadersFrame)

}

func (rl *clientConnReadLoop) processHeaders(f *MetaHeadersFrame) error {
	cs := rl.streamByID(f.StreamID)
	if cs == nil {
		// We'd get here if we canceled a request while the
		// server had its response still in flight. So if this
		// was just something we canceled, ignore it.
		return nil
	}
	if cs.readClosed {
		rl.endStreamError(cs, StreamError{
			StreamID: f.StreamID,
			Code:     ErrCodeProtocol,
			Cause:    errors.New("protocol error: headers after END_STREAM"),
		})
		return nil
	}
	if !cs.firstByte {
		if cs.trace != nil {
			// TODO(bradfitz): move first response byte earlier,
			// when we first read the 9 byte header, not waiting
			// until all the HEADERS+CONTINUATION frames have been
			// merged. This works for now.
			traceFirstResponseByte(cs.trace)
		}
		cs.firstByte = true
	}
	if !cs.pastHeaders {
		cs.pastHeaders = true
	} else {
		return rl.processTrailers(cs, f)
	}

	res, err := rl.handleResponse(cs, f)
	if err != nil {
		if _, ok := err.(ConnectionError); ok {
			return err
		}
		// Any other error type is a stream error.
		rl.endStreamError(cs, StreamError{
			StreamID: f.StreamID,
			Code:     ErrCodeProtocol,
			Cause:    err,
		})
		return nil // return nil from process* funcs to keep conn alive
	}
	if res == nil {
		// (nil, nil) special case. See handleResponse docs.
		return nil
	}
	cs.resTrailer = &res.Trailer
	cs.res = res
	close(cs.respHeaderRecv)
	if f.StreamEnded() {
		rl.endStream(cs)
	}
	return nil
}