SetupRequest conundrum

gistfile1.txt

#include <stdlib.h>
#include <stdio.h>
#include "libxcb-1.11/src/xcb.h"

/*
gcc testxcb.c libxcb-1.11/src/.libs/libxcb.a -lXau; ./a.out
*/

char bytes[] = { ... capture data here...};

int main(void) {
	xcb_setup_request_t *r = (xcb_setup_request_t *)bytes;
	printf("name: %s (%d)\n", xcb_setup_request_authorization_protocol_name(r), xcb_setup_request_authorization_protocol_name_length(r));
	char *data = xcb_setup_request_authorization_protocol_data(r);
	int len = xcb_setup_request_authorization_protocol_data_length(r);
	printf("data (%d):", len);
	int i;
	for (i = 0; i < len; ++i) {
		printf(" %02x", (unsigned char)data[i]);
	}
	printf("\n");
	return 0;
}