On Wed, Jul 19, 2006 at 03:03:24PM +0530, Chinmaya Mishra wrote:
> Hi,
>
> Can you provide an example how to invoke ioctl on
> device in kernel module.
>
> For example. I want to find out the IP address of
> my eth0 and I want to make SIOCSIFADDR on it from
> kernel module.
Recall that in kernel space YOU are the kernel :), so you won't be
syscall()ing, albeit some cases where it's easy to do a function call
to a syscall's _implementation_.
Usual path is to dig, grep into kernel srcs to find HOW it has been
implemented and copy&adapt code from there, net/ipv4/ is a good
place to start.
Below is a code snippet that gets iface's ipaddr using
inet_select_addr() which selects src addr from routing
table (the "src" you'll see with eg.: ip route get 1.1.1.1)
#include <linux/module.h>
#include <linux/inetdevice.h>
#include <linux/rtnetlink.h>
u32 get_default_ipaddr_by_devname(const char *devname)
{
u32 addr;
struct net_device *dev;
if (!devname) return 0;
/* find netdev by name, increment refcnt */
dev=dev_get_by_name(devname);
if (!dev) return 0;
/* get ip addr from rtable (global scope) */
addr = inet_select_addr(dev, 0, RT_SCOPE_UNIVERSE);
/* decrement netdev refcnt */
dev_put(dev);
return addr;
}
Regards...
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