Properly detect loops by recording the interface pointer in an mtag.

For now, preserve the gif_called functionality to limit the nesting
level because uncontrolled nesting can easily cause the kernel stack
exhaustion.  Rumors are it should be shot to allow people to easily
shoot themselves in the foot, but I have ran out of cartridges.  ;)

1 files changed, 3 insertions, 0 deletions

diff --git a/sys/net/if_gif.h b/sys/net/if_gif.h
index 8a0ac56..c3a9df2 100644
--- a/sys/net/if_gif.h
+++ b/sys/net/if_gif.h
@@ -81,6 +81,9 @@ struct gif_softc {
 #define	GIF_MTU_MIN	(1280)	/* Minimum MTU */
 #define	GIF_MTU_MAX	(8192)	/* Maximum MTU */
 
+#define	MTAG_GIF	1080679712
+#define	MTAG_GIF_CALLED	0
+
 /* Prototypes */
 void gifattach0(struct gif_softc *);
 void gif_input(struct mbuf *, int, struct ifnet *);