examples/genl/genl-group-events.c

/* This example is placed in the public domain. */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>

#include <libmnl/libmnl.h>
#include <linux/genetlink.h>

static int group;

static int data_cb(const struct nlmsghdr *nlh, void *data)
{
	printf("received event type=%d from genetlink group %d\n",
		nlh->nlmsg_type, group);
	return MNL_CB_OK;
}

int main(int argc, char *argv[])
{
	struct mnl_socket *nl;
	char buf[MNL_SOCKET_BUFFER_SIZE];
	int ret;

	if (argc != 2) {
		printf("%s [group]\n", argv[0]);
		exit(EXIT_FAILURE);
	}
	group = atoi(argv[1]);

	nl = mnl_socket_open(NETLINK_GENERIC);
	if (nl == NULL) {
		perror("mnl_socket_open");
		exit(EXIT_FAILURE);
	}

	if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
		perror("mnl_socket_bind");
		exit(EXIT_FAILURE);
	}

	if (mnl_socket_setsockopt(nl, NETLINK_ADD_MEMBERSHIP, &group,
				  sizeof(int)) < 0) {
		perror("mnl_socket_setsockopt");
		exit(EXIT_FAILURE);
	}

	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
	while (ret > 0) {
		ret = mnl_cb_run(buf, ret, 0, 0, data_cb, NULL);
		if (ret <= 0)
			break;
		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
	}
	if (ret == -1) {
		perror("error");
		exit(EXIT_FAILURE);
	}

	mnl_socket_close(nl);

	return 0;
}