/*
 * DF-3298 PoC helper - force carp(4) state via SIOCSVH (carpr_state).
 * Does read-modify-write (like ifconfig) so the key/params survive.
 *
 * Build: cc -O2 -o setstate setstate.c
 * Usage: setstate carp0 2     (2 = MASTER)
 */
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/ip_carp.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

int
main(int argc, char **argv)
{
	struct carpreq carpr;
	struct ifreq ifr;
	int s, state;

	if (argc != 3) {
		fprintf(stderr, "usage: %s <carpif> <0|1|2>\n", argv[0]);
		return 2;
	}
	state = atoi(argv[2]);

	s = socket(AF_INET, SOCK_DGRAM, 0);
	if (s < 0) { perror("socket"); return 1; }

	memset(&ifr, 0, sizeof(ifr));
	memset(&carpr, 0, sizeof(carpr));
	strlcpy(ifr.ifr_name, argv[1], sizeof(ifr.ifr_name));
	ifr.ifr_data = (caddr_t)&carpr;

	if (ioctl(s, SIOCGVH, &ifr) == -1) {
		perror("SIOCGVH"); return 1;
	}
	carpr.carpr_state = state;
	if (ioctl(s, SIOCSVH, &ifr) == -1) {
		perror("SIOCSVH"); return 1;
	}
	printf("%s: state set to %d\n", argv[1], state);
	return 0;
}