On Nov 19 2007 14:57, Giacomo wrote:
>
> I have written a kernel function which needs to get the IP address
> of an active network interface given its name.
And why is that?
If you are trying to write a netfilter module, just use the 'in' or
'out' parameters.
If not, try posting to netdev@xxxxxxxxxxxxxxx instead.
> The actual implementation i have done is like this
> but i suspect this does not always work.
> Is there any API already provided by the kernel to do the same?
>
> -- actual implementation: ---
>
> /* returns in *addr the internet address having the name ifname */
> int get_ifaddr_by_name(const char *ifname, __u32 * addr)
Problematic: Does not handle anything besides IPv4.
> {
> struct net_device *pnet_device;
> struct in_device *pin_device;
> struct in_ifaddr* inet_ifaddr;
>
> read_lock_bh(&dev_base_lock);
> #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22)
> pnet_device = dev_base;
> #else
> pnet_device = first_net_device();
> #endif
There is for_each_netdev().
> while (pnet_device != NULL)
> {
> if ((netif_running(pnet_device))
> && (pnet_device->ip_ptr != NULL)
> && (strcmp(pnet_device->name, ifname) == 0))
> {
> pin_device =
> (struct in_device *) pnet_device->ip_ptr;
> inet_ifaddr = pin_device->ifa_list;
> if(inet_ifaddr == NULL)
> {
> printk("ifa_list is null!\n");
> break;
> }
> /* ifa_local: ifa_address is the remote point in ppp */
> *addr = (inet_ifaddr->ifa_local);
> read_unlock_bh(&dev_base_lock);
> return 1;
> }
> #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22)
> pnet_device = pnet_device->next;
> #else
> pnet_device = next_net_device(pnet_device);
> #endif
>
> }
>
> read_unlock_bh(&dev_base_lock);
> return -1; /* address not found! */
> }
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