device: refactor nm_device_set_ip_ifindex() and set_ip_iface()

- don't even bother to look into the platform cache, but use
  if_indextoname() / if_nametoindex(). In most cases, we obtained
  the ifindex/ifname not from the platform cache in the first
  place. Hence, there is a race, where the interface might not
  exist.
  However, try to process events of the platform cache, hoping
  that the cache contains an interface for the given ifindex/ifname.

- let set_ip_ifindex() and set_ip_iface() both return a boolean
  value to indicate whether a ip-interface is set or not. That is,
  whether we have a positive ip_ifindex. That seems more interesting
  information, then to return whether anything changed.

- as before, set_ip_ifindex() can only clear an ifindex/ifname,
  or error out without doing anything. That is different from
  set_ip_iface(), which will also set an ifname if no ifindex
  can be resolved. That is curreently ugly, because then ip-ifindex
  and ip-iface don't agree. That shall be improved in the future
  by:
  - trying to set an interface that cannot be resolved shall
    lead to a disconnect in any case.
  - we shall make less use of the ip-iface and rely more on the
    ifindex.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/devices/wwan/nm-device-modem.c b/src/devices/wwan/nm-device-modem.c
index ccf6e17da2..cec9e5327b 100644
--- a/src/devices/wwan/nm-device-modem.c
+++ b/src/devices/wwan/nm-device-modem.c
@@ -263,17 +263,17 @@ static void
 data_port_changed_cb (NMModem *modem, GParamSpec *pspec, gpointer user_data)
 {
 	NMDevice *self = NM_DEVICE (user_data);
-	gboolean changed;
+	gboolean has_ifindex;
 
 	/* We set the IP iface in the device as soon as we know it, so that we
 	 * properly ifup it if needed */
-	changed = nm_device_set_ip_iface (self, nm_modem_get_data_port (modem));
+	has_ifindex = nm_device_set_ip_iface (self, nm_modem_get_data_port (modem));
 
 	/* Disable IPv6 immediately on the interface since NM handles IPv6
 	 * internally, and leaving it enabled could allow the kernel's IPv6
 	 * RA handling code to run before NM is ready.
 	 */
-	if (changed)
+	if (has_ifindex)
 		nm_device_ipv6_sysctl_set (self, "disable_ipv6", "1");
 }