#include <nghttp2/nghttp2.h>

ssize_t nghttp2_pack_settings_payload(uint8_t *buf, size_t buflen, const nghttp2_settings_entry *iv, size_t niv)

Serializes the SETTINGS values iv in the buf. The size of the buf is specified by buflen. The number of entries in the iv array is given by niv. The required space in buf for the niv entries is 8*niv bytes and if the given buffer is too small, an error is returned. This function is used mainly for creating a SETTINGS payload to be sent with the HTTP2-Settings header field in an HTTP Upgrade request. The data written in buf is NOT base64url encoded and the application is responsible for encoding.

This function returns the number of bytes written in buf, or one of the following negative error codes:

The iv contains duplicate settings ID or invalid value.
The provided buflen size is too small to hold the output.