Introduce bpf_mtap_ether(), which for the benefit of bpf listeners

creates the VLAN encapsulation from the tag stored in the mbuf
header.  Idea from FreeBSD, input from claudio@ and canacar@.

Switch all hardware VLAN enabled drivers to the new function.

ok claudio@

2 files changed, 52 insertions, 2 deletions

diff --git a/sys/net/bpf.c b/sys/net/bpf.c
index 8f1781bf447..0172c5d8f85 100644
--- a/sys/net/bpf.c
+++ b/sys/net/bpf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bpf.c,v 1.69 2008/09/17 20:10:37 chl Exp $	*/
+/*	$OpenBSD: bpf.c,v 1.70 2008/11/09 15:08:26 naddy Exp $	*/
 /*	$NetBSD: bpf.c,v 1.33 1997/02/21 23:59:35 thorpej Exp $	*/
 
 /*
@@ -59,6 +59,11 @@
 #include <netinet/in.h>
 #include <netinet/if_ether.h>
 
+#include "vlan.h"
+#if NVLAN > 0
+#include <net/if_vlan_var.h>
+#endif
+
 #define BPF_BUFSIZE 32768
 
 #define PRINET  26			/* interruptible */
@@ -1237,6 +1242,50 @@ bpf_mtap_af(caddr_t arg, u_int32_t af, struct mbuf *m, u_int direction)
 }
 
 /*
+ * Incoming linkage from device drivers, where we have a mbuf chain
+ * but need to prepend a VLAN encapsulation header.
+ *
+ * Con up a minimal dummy header to pacify bpf.  Allocate (only) a
+ * struct m_hdr on the stack.  This is safe as bpf only reads from the
+ * fields in this header that we initialize, and will not try to free
+ * it or keep a pointer to it.
+ */
+void
+bpf_mtap_ether(caddr_t arg, struct mbuf *m, u_int direction)
+{
+#if NVLAN > 0
+	struct m_hdr mh;
+	struct ether_vlan_header evh;
+
+	if ((m->m_flags & M_VLANTAG) == 0)
+#endif
+	{
+		bpf_mtap(arg, m, direction);
+		return;
+	}
+
+#if NVLAN > 0
+	bcopy(mtod(m, char *), &evh, ETHER_HDR_LEN);
+	evh.evl_proto = evh.evl_encap_proto;
+	evh.evl_encap_proto = htons(ETHERTYPE_VLAN);
+	evh.evl_tag = htons(m->m_pkthdr.ether_vtag);
+	m->m_len -= ETHER_HDR_LEN;
+	m->m_data += ETHER_HDR_LEN;
+
+	mh.mh_flags = 0;
+	mh.mh_next = m;
+	mh.mh_len = sizeof(evh);
+	mh.mh_data = (caddr_t)&evh;
+
+	bpf_mtap(arg, (struct mbuf *) &mh, direction);
+	m->m_flags |= mh.mh_flags & M_FILDROP;
+
+	m->m_len += ETHER_HDR_LEN;
+	m->m_data -= ETHER_HDR_LEN;
+#endif
+}
+
+/*
  * Move the packet data from interface memory (pkt) into the
  * store buffer.  Return 1 if it's time to wakeup a listener (buffer full),
  * otherwise 0.  "copy" is the routine called to do the actual data
diff --git a/sys/net/bpf.h b/sys/net/bpf.h
index 88d0a7fbc7f..fcf4c2588ec 100644
--- a/sys/net/bpf.h
+++ b/sys/net/bpf.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bpf.h,v 1.35 2008/06/29 19:31:16 deraadt Exp $	*/
+/*	$OpenBSD: bpf.h,v 1.36 2008/11/09 15:08:26 naddy Exp $	*/
 /*	$NetBSD: bpf.h,v 1.15 1996/12/13 07:57:33 mikel Exp $	*/
 
 /*
@@ -273,6 +273,7 @@ int	 bpf_tap(caddr_t, u_char *, u_int, u_int);
 void	 bpf_mtap(caddr_t, struct mbuf *, u_int);
 void	 bpf_mtap_hdr(caddr_t, caddr_t, u_int, struct mbuf *, u_int);
 void	 bpf_mtap_af(caddr_t, u_int32_t, struct mbuf *, u_int);
+void	 bpf_mtap_ether(caddr_t, struct mbuf *, u_int);
 void	 bpfattach(caddr_t *, struct ifnet *, u_int, u_int);
 void	 bpfdetach(struct ifnet *);
 void	 bpfilterattach(int);