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, 4 insertions, 0 deletions

diff --git a/mac80211.c b/mac80211.c
index c089574..09f15b7 100644
--- a/mac80211.c
+++ b/mac80211.c
@@ -226,6 +226,10 @@ void enter_rfmon_mac80211(const char *device, char **mondev)
 		char mondevice[32];
 
 		slprintf(mondevice, sizeof(mondevice), "mon%u", n);
+
+		if (device_ifindex_get(mondevice) > 0)
+			continue;
+
 		ret = nl80211_add_mon_if(&nlstate, device, mondevice);
 		if (ret == 0) {
 			*mondev = xstrdup(mondevice);