#include <nghttp2/nghttp2.h>

int nghttp2_submit_trailer(nghttp2_session *session, int32_t stream_id, const nghttp2_nv *nva, size_t nvlen)

Submits trailer fields HEADERS against the stream stream_id.

The nva is an array of name/value pair nghttp2_nv with nvlen elements. The application must not include pseudo-header fields (headers whose names starts with ":") in nva.

This function creates copies of all name/value pairs in nva. It also lower-cases all names in nva. The order of elements in nva is preserved. For header fields with NGHTTP2_NV_FLAG_NO_COPY_NAME and NGHTTP2_NV_FLAG_NO_COPY_VALUE are set, header field name and value are not copied respectively. With NGHTTP2_NV_FLAG_NO_COPY_NAME, application is responsible to pass header field name in lowercase. The application should maintain the references to them until nghttp2_on_frame_send_callback or nghttp2_on_frame_not_send_callback is called.

For server, trailer fields must follow response HEADERS or response DATA without END_STREAM flat set. The library does not enforce this requirement, and applications should do this for themselves. If nghttp2_submit_trailer() is called before any response HEADERS submission (usually by nghttp2_submit_response()), the content of nva will be sent as response headers, which will result in error.

This function has the same effect with nghttp2_submit_headers(), with flags = NGHTTP2_FLAG_END_STREAM and both pri_spec and stream_user_data to NULL.

To submit trailer fields after nghttp2_submit_response() is called, the application has to specify nghttp2_data_provider to nghttp2_submit_response(). Inside of nghttp2_data_source_read_callback, when setting NGHTTP2_DATA_FLAG_EOF, also set NGHTTP2_DATA_FLAG_NO_END_STREAM. After that, the application can send trailer fields using nghttp2_submit_trailer(). nghttp2_submit_trailer() can be used inside nghttp2_data_source_read_callback.

This function returns 0 if it succeeds and stream_id is -1. Otherwise, this function returns 0 if it succeeds, or one of the following negative error codes:

Out of memory.
The stream_id is 0.