mac80211: Check existence of generated monX device

Fix then case when netsniff-ng fails if there is already an existing
monX device while generating one.

Signed-off-by: Vadim Kochan <vadim4j@gmail.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

1 files changed, 1 insertions, 0 deletions

diff --git a/dev.h b/dev.h
index 2d5f056..adb1c43 100644
--- a/dev.h
+++ b/dev.h
@@ -7,6 +7,7 @@
 extern size_t device_mtu(const char *ifname);
 extern int device_address(const char *ifname, int af, struct sockaddr_storage *ss);
 extern int device_ifindex(const char *ifname);
+extern int device_ifindex_get(const char *ifname);
 extern int device_type(const char *ifname);
 extern short device_get_flags(const char *ifname);
 extern void device_set_flags(const char *ifname, const short flags);