rtnetlink_test.c

rtnetlink_test.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <asm/types.h>
#include <sys/socket.h>
#include <linux/netlink.h>

#include <linux/rtnetlink.h>

struct sockaddr_nl sa;
#define handle_error(msg) \
do { perror(msg); exit(EXIT_FAILURE); } while (0)

void read_msgs( );
int fd;

int main (int argc, char *argv[])
{
	int rc;
	memset (&sa, 0, sizeof(sa));
	sa.nl_family = AF_NETLINK;
	sa.nl_groups = RTMGRP_LINK;

	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	rc = bind(fd, (struct sockaddr*)&sa, sizeof(sa));
	if (rc == -1) {
		fprintf(stderr, "bind failure\n");
		exit(1);
	}
	read_msgs();

	return 0;
	}

void read_msgs(void)
{
	int len;
	char buf[4096];
	struct iovec iov = { buf, sizeof(buf) };
	struct msghdr nlmsg = { (void *)&sa, sizeof(sa), &iov, 1, NULL, 0, 0 };
	struct nlmsghdr *nh;
	struct ifinfomsg *msg;
	struct rtattr *attr;
	int bytes;

	printf("enter recvmsg\n");
	len = recvmsg (fd, &nlmsg, 0);
	printf("got recvmsg");

	for (nh = (struct nlmsghdr *) buf; NLMSG_OK (nh, len); nh = NLMSG_NEXT (nh, len)) {
		/* The end of multipart message. */
		if (nh->nlmsg_type == NLMSG_DONE)
			return;

		if (nh->nlmsg_type == NLMSG_ERROR) {
			printf("Error\n");
			/* Do some error handling. */
		}

		msg = (struct ifinfomsg *) NLMSG_DATA(nh);
		printf("link index: %d\n", msg->ifi_index);
	}
}