Hi,
I have been trying to write a program that uses the new netlink
code but I haven't been able make it work. Even the example code
from rtnetlink(3) doesn't work. 'ip' utility from iproute2 package
works so I assume the kernel is configured properly.
Here is the slightly modified example code:
--- cut ---
#include <stdio.h>
#include <asm/types.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <errno.h>
#include <stdlib.h>
#include <net/if.h>
#include <sys/ioctl.h>
/* This should change the MTU of eth1 to 1000.
*/
int main()
{
struct {
struct nlmsghdr nh;
struct ifinfomsg info;
char attrbuf[512];
} req;
struct rtattr *rta;
struct ifreq if_req;
unsigned int mtu = 1000;
int rtnetlink_socket = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
int ioctl_socket = socket(AF_INET, SOCK_DGRAM, 0);
memset(&if_req, 0, sizeof(if_req));
strncpy(if_req.ifr_name, "eth1", IFNAMSIZ);
ioctl(ioctl_socket, SIOCGIFINDEX, &if_req);
printf("ifr_ifindex = %d.\n", if_req.ifr_ifindex);
memset(&req, 0, sizeof(req));
req.nh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
req.nh.nlmsg_flags = NLM_F_REQUEST;
req.nh.nlmsg_type = RTM_NEWLINK;
req.info.ifi_family = AF_UNSPEC;
req.info.ifi_index = if_req.ifr_ifindex;
req.info.ifi_change = 0xffffffff;
rta = (struct rtattr*)(((char*) &req) + NLMSG_ALIGN(req.nh.nlmsg_len));
rta->rta_type = IFLA_MTU;
rta->rta_len = sizeof(unsigned int);
req.nh.nlmsg_len = NLMSG_ALIGN(req.nh.nlmsg_len)+RTA_LENGTH(sizeof(mtu));
memcpy(RTA_DATA(rta), &mtu, sizeof (mtu));
send(rtnetlink_socket, &req, req.nh.nlmsg_len, 0);
return 0;
}
--- cut ---
What puzzles me is that if I run it as non-root it doesn't give
any errors like 'ip' does.
/* Tuomas M��tt�nen [EMAIL PROTECTED]
* Insin��rinkatu 60 C190
* 33720 Tampere Linux - the choice of a GNU generation!
*/
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