#include <nghttp2/nghttp2.h>

void nghttp2_option_set_no_recv_client_magic(nghttp2_option *option, int val)

By default, nghttp2 library, if configured as server, requires first 24 bytes of client magic byte string (MAGIC). In most cases, this will simplify the implementation of server. But sometimes server may want to detect the application protocol based on first few bytes on clear text communication.

If this option is used with nonzero val, nghttp2 library does not handle MAGIC. It still checks following SETTINGS frame. This means that applications should deal with MAGIC by themselves.

If this option is not used or used with zero value, if MAGIC does not match NGHTTP2_CLIENT_MAGIC, nghttp2_session_recv() and nghttp2_session_mem_recv() will return error NGHTTP2_ERR_BAD_CLIENT_MAGIC, which is fatal error.