Re: libdnet problem with monitor mode interfaces

[David Fifield <david () bamsoftware com>]

On Tue, May 29, 2012 at 03:20:48PM +0100, Djalal Harouni wrote:
> On Tue, May 29, 2012 at 03:06:42PM +0100, Djalal Harouni wrote:
> [...]
> > > Not sure how to fix cleanly, but ignoring the return code of
> > > addr_ston() line 516 makes it work.
> > Ok, it seems for the monitor mode the address family will be
> > set to ARPHRD_IEEE80211_RADIOTAP == 803 [1] which is not supported by
> > addr_ston().
> >
> > We could replace that addr_ston() in _intf_get_noalias() by:
> >  memcpy(&entry->intf_link_addr.addr_eth, &ifr.ifr_addr.sa_data, ETH_ADDR_LEN)
> Actually after responding to David I think that we should just use
> memcpy() to get the hardware address, I don't know why there is the
> addr_ston() ? and in other places they use addr_ntos()...
>
> Another patch is attached, this will show if you have an interface with
> the monitor mode and if the inet address is null.

> Index: libdnet-stripped/src/intf.c
> ===================================================================
> --- libdnet-stripped/src/intf.c       (revision 28753)
> +++ libdnet-stripped/src/intf.c       (working copy)
> @@ -513,8 +513,7 @@
>  #if defined(SIOCGIFHWADDR)
>               if (ioctl(intf->fd, SIOCGIFHWADDR, &ifr) < 0)
>                       return (-1);
> -             if (addr_ston(&ifr.ifr_addr, &entry->intf_link_addr) < 0)
> -                     return (-1);
> +             memcpy(&entry->intf_link_addr, &ifr.ifr_addr.sa_data, ETH_ADDR_LEN);
>  #elif defined(SIOCRPHYSADDR)
>               /* Tru64 */
>               struct ifdevea *ifd = (struct ifdevea *)&ifr; /* XXX */

Wouldn't it be better to add this support to addr_ston? There is already
the same memcpy in addr_ston, but only for the types AF_UNSPEC and
ARP_HRD_ETH. Does adding ARPHRD_IEEE80211_RADIOTAP in addr_ston solve
the problem too?

addr_ston converts a struct sockaddr to libdnet's own struct addr.
addr_ntos goes the other direction. I remember them as "sockaddr to
numeric" and "numeric to sockaddr."

David Fifield
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