Type Definition libnghttp2_sys::nghttp2_send_data_callback

type nghttp2_send_data_callback = Option<unsafe extern "C" fn(session: *mut nghttp2_session, frame: *mut nghttp2_frame, framehd: *const u8, length: usize, source: *mut nghttp2_data_source, user_data: *mut c_void) -> c_int>;

@functypedef

Callback function invoked when :enum:NGHTTP2_DATA_FLAG_NO_COPY is used in :type:nghttp2_data_source_read_callback to send complete DATA frame.

The |frame| is a DATA frame to send. The |framehd| is the serialized frame header (9 bytes). The |length| is the length of application data to send (this does not include padding). The |source| is the same pointer passed to :type:nghttp2_data_source_read_callback.

The application first must send frame header |framehd| of length 9 bytes. If frame->data.padlen > 0, send 1 byte of value frame->data.padlen - 1. Then send exactly |length| bytes of application data. Finally, if frame->data.padlen > 1, send frame->data.padlen - 1 bytes of zero as padding.

The application has to send complete DATA frame in this callback. If all data were written successfully, return 0.

If it cannot send any data at all, just return :enum:NGHTTP2_ERR_WOULDBLOCK; the library will call this callback with the same parameters later (It is recommended to send complete DATA frame at once in this function to deal with error; if partial frame data has already sent, it is impossible to send another data in that state, and all we can do is tear down connection). When data is fully processed, but application wants to make nghttp2_session_mem_send() or nghttp2_session_send() return immediately without processing next frames, return :enum:NGHTTP2_ERR_PAUSE. If application decided to reset this stream, return :enum:NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE, then the library will send RST_STREAM with INTERNAL_ERROR as error code. The application can also return :enum:NGHTTP2_ERR_CALLBACK_FAILURE, which will result in connection closure. Returning any other value is treated as :enum:NGHTTP2_ERR_CALLBACK_FAILURE is returned.