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, 12 insertions, 3 deletions

diff --git a/dev.c b/dev.c
index b3249e6..45659a8 100644
--- a/dev.c
+++ b/dev.c
@@ -13,7 +13,7 @@
 #include "link.h"
 #include "built_in.h"
 
-int device_ifindex(const char *ifname)
+int device_ifindex_get(const char *ifname)
 {
 	int ret, sock, index;
 	struct ifreq ifr;
@@ -27,8 +27,8 @@ int device_ifindex(const char *ifname)
 	strlcpy(ifr.ifr_name, ifname, IFNAMSIZ);
 
 	ret = ioctl(sock, SIOCGIFINDEX, &ifr);
-	if (unlikely(ret))
-		panic("Cannot get ifindex from device!\n");
+	if (ret)
+		return -1;
 
 	index = ifr.ifr_ifindex;
 	close(sock);
@@ -36,6 +36,15 @@ int device_ifindex(const char *ifname)
 	return index;
 }
 
+int device_ifindex(const char *ifname)
+{
+	int index = device_ifindex_get(ifname);
+	if (unlikely(index <= 0))
+		panic("Cannot get ifindex from device!\n");
+
+	return index;
+}
+
 int device_type(const char *ifname)
 {
 	int ret, sock, type;