From 682952bd0cc8980caff3a517215b6bff24209daa Mon Sep 17 00:00:00 2001
From: Reyk Floeter <reyk@cvs.openbsd.org>
Date: Fri, 7 Jan 2005 16:28:39 +0000
Subject: add support for BIOCGDLTLIST and BIOCSDLT, see bpf(4)

ok canacar@, fgsch@, tested by some other people
---
 share/man/man4/bpf.4              | 40 +++++++++++++++++-
 sys/net/bpf.c                     | 85 ++++++++++++++++++++++++++++++++++++++-
 sys/net/bpf.h                     | 13 +++++-
 sys/net80211/ieee80211_radiotap.h |  7 +---
 4 files changed, 136 insertions(+), 9 deletions(-)

diff --git a/share/man/man4/bpf.4 b/share/man/man4/bpf.4
index 59caba0ac2a..348ec0d7ea2 100644
--- a/share/man/man4/bpf.4
+++ b/share/man/man4/bpf.4
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: bpf.4,v 1.22 2004/05/31 17:06:37 canacar Exp $
+.\"	$OpenBSD: bpf.4,v 1.23 2005/01/07 16:28:38 reyk Exp $
 .\"     $NetBSD: bpf.4,v 1.7 1995/09/27 18:31:50 thorpej Exp $
 .\"
 .\" Copyright (c) 1990 The Regents of the University of California.
@@ -146,6 +146,44 @@ The device types, prefixed with
 .Dq DLT_ ,
 are defined in
 .Aq Pa net/bpf.h .
+.It Dv BIOCGDLTLIST (struct bpf_dltlist)
+Returns an array of the available types of the data link layer
+underlying the attached interface:
+.Bd -literal -offset indent
+struct bpf_dltlist {
+	u_int bfl_len;
+	u_int *bfl_list;
+};
+.Ed
+.Pp
+The available types are returned in the array pointed to by the
+.Va bfl_list
+field while their length in
+.Vt u_int
+is supplied to the
+.Va bfl_len
+field.
+.Er ENOMEM
+is returned if there is not enough buffer space and
+.Er EFAULT
+is returned if a bad address is encountered. The
+.Va bfl_len
+field is modified on return to indicate the actual length in
+.Vt u_int
+of the array returned.
+If
+.Va bfl_list
+is
+.Dv NULL ,
+the
+.Va bfl_len
+field is set to indicate the required length of the array in
+.Vt u_int .
+.It Dv BIOCSDLT (u_int)
+Changes the type of the data link layer underlying the attached interface.
+.Er EINVAL
+is returned if no interface has been specified or the specified
+type is not available for the interface.
 .It Dv BIOCPROMISC
 Forces the interface into promiscuous mode.
 All packets, not just those destined for the local host, are processed.
diff --git a/sys/net/bpf.c b/sys/net/bpf.c
index 25440ec33ec..b1d29bba72d 100644
--- a/sys/net/bpf.c
+++ b/sys/net/bpf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bpf.c,v 1.55 2004/12/17 15:56:58 reyk Exp $	*/
+/*	$OpenBSD: bpf.c,v 1.56 2005/01/07 16:28:38 reyk Exp $	*/
 /*	$NetBSD: bpf.c,v 1.33 1997/02/21 23:59:35 thorpej Exp $	*/
 
 /*
@@ -92,6 +92,8 @@ static __inline void bpf_wakeup(struct bpf_d *);
 void	bpf_catchpacket(struct bpf_d *, u_char *, size_t, size_t,
 	    void (*)(const void *, void *, size_t));
 void	bpf_reset_d(struct bpf_d *);
+int	bpf_getdltlist(struct bpf_d *, struct bpf_dltlist *);
+int	bpf_setdlt(struct bpf_d *, u_int);
 
 void	filt_bpfrdetach(struct knote *);
 int	filt_bpfread(struct knote *, long);
@@ -573,7 +575,9 @@ bpf_reset_d(struct bpf_d *d)
  *  BIOCSETF		Set ethernet read filter.
  *  BIOCFLUSH		Flush read packet buffer.
  *  BIOCPROMISC		Put interface into promiscuous mode.
+ *  BIOCGDLTLIST	Get supported link layer types.
  *  BIOCGDLT		Get link layer type.
+ *  BIOCSDLT		Set link layer type.
  *  BIOCGETIF		Get interface name.
  *  BIOCSETIF		Set interface.
  *  BIOCSRTIMEOUT	Set read timeout.
@@ -598,6 +602,7 @@ bpfioctl(dev_t dev, u_long cmd, caddr_t addr, int flag, struct proc *p)
 		case BIOCGBLEN:
 		case BIOCFLUSH:
 		case BIOCGDLT:
+		case BIOCGDLTLIST:
 		case BIOCGETIF:
 		case BIOCGRTIMEOUT:
 		case BIOCGSTATS:
@@ -705,6 +710,16 @@ bpfioctl(dev_t dev, u_long cmd, caddr_t addr, int flag, struct proc *p)
 		splx(s);
 		break;
 
+	/*
+	 * Get a list of supported device parameters.
+	 */
+	case BIOCGDLTLIST:
+		if (d->bd_bif == NULL)
+			error = EINVAL;
+		else
+			error = bpf_getdltlist(d, (struct bpf_dltlist *)addr);
+		break;
+
 	/*
 	 * Get device parameters.
 	 */
@@ -715,6 +730,16 @@ bpfioctl(dev_t dev, u_long cmd, caddr_t addr, int flag, struct proc *p)
 			*(u_int *)addr = d->bd_bif->bif_dlt;
 		break;
 
+	/*
+	 * Set device parameters.
+	 */
+	case BIOCSDLT:
+		if (d->bd_bif == NULL)
+			error = EINVAL;
+		else
+			error = bpf_setdlt(d, *(u_int *)addr);
+		break;
+
 	/*
 	 * Set interface name.
 	 */
@@ -1420,3 +1445,61 @@ bpfilter_destroy(struct bpf_d *bd)
 	LIST_REMOVE(bd, bd_list);
 	free(bd, M_DEVBUF);
 }
+
+/*
+ * Get a list of available data link type of the interface.
+ */
+int
+bpf_getdltlist(struct bpf_d *d, struct bpf_dltlist *bfl)
+{
+	int n, error;
+	struct ifnet *ifp;
+	struct bpf_if *bp;
+
+	ifp = d->bd_bif->bif_ifp;
+	n = 0;
+	error = 0;
+	for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
+		if (bp->bif_ifp != ifp)
+			continue;
+		if (bfl->bfl_list != NULL) {
+			if (n >= bfl->bfl_len)
+				return (ENOMEM);
+			error = copyout(&bp->bif_dlt,
+			    bfl->bfl_list + n, sizeof(u_int));
+			if (error)
+				break;
+		}
+		n++;
+	}
+
+	bfl->bfl_len = n;
+	return (error);
+}
+
+/*
+ * Set the data link type of a BPF instance.
+ */
+int
+bpf_setdlt(struct bpf_d *d, u_int dlt)
+{
+	int s;
+	struct ifnet *ifp;
+	struct bpf_if *bp;
+
+	if (d->bd_bif->bif_dlt == dlt)
+		return (0);
+	ifp = d->bd_bif->bif_ifp;
+	for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
+		if (bp->bif_ifp == ifp && bp->bif_dlt == dlt)
+			break;
+	}
+	if (bp == NULL)
+		return (EINVAL);
+	s = splimp();
+	bpf_detachd(d);
+	bpf_attachd(d, bp);
+	bpf_reset_d(d);
+	splx(s);
+	return (0);
+}
diff --git a/sys/net/bpf.h b/sys/net/bpf.h
index da4dc8a06ae..c8465ea15c7 100644
--- a/sys/net/bpf.h
+++ b/sys/net/bpf.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bpf.h,v 1.29 2004/12/17 15:56:58 reyk Exp $	*/
+/*	$OpenBSD: bpf.h,v 1.30 2005/01/07 16:28:38 reyk Exp $	*/
 /*	$NetBSD: bpf.h,v 1.15 1996/12/13 07:57:33 mikel Exp $	*/
 
 /*
@@ -115,6 +115,8 @@ struct bpf_version {
 #define	BIOCSETWF	_IOW('B',119, struct bpf_program)
 #define BIOCGFILDROP	_IOR('B',120, u_int)
 #define BIOCSFILDROP	_IOW('B',121, u_int)
+#define BIOCSDLT	_IOW('B',122, u_int)
+#define BIOCGDLTLIST	_IOWR('B',123, struct bpf_dltlist)
 
 struct bpf_timeval {
 	u_int32_t	tv_sec;
@@ -174,6 +176,7 @@ struct bpf_hdr {
 #define DLT_PPP_ETHER		51	/* PPP over Ethernet; session only w/o ether header */
 #define DLT_IEEE802_11		105	/* IEEE 802.11 wireless */
 #define DLT_PFLOG		117	/* Packet filter logging, by pcap people */
+#define DLT_IEEE802_11_RADIO	127	/* IEEE 802.11 plus WLAN header */
 
 /*
  * The instruction encodings.
@@ -241,6 +244,14 @@ struct bpf_insn {
 	u_int32_t	k;
 };
 
+/*
+ * Structure to retrieve available DLTs for the interface.
+ */
+struct bpf_dltlist {
+	u_int	bfl_len;	/* number of bfd_list array */
+	u_int	*bfl_list;	/* array of DLTs */
+};
+
 /*
  * Macros for insn array initializers.
  */
diff --git a/sys/net80211/ieee80211_radiotap.h b/sys/net80211/ieee80211_radiotap.h
index d0559e3fc01..1d355d2af0e 100644
--- a/sys/net80211/ieee80211_radiotap.h
+++ b/sys/net80211/ieee80211_radiotap.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ieee80211_radiotap.h,v 1.4 2004/12/30 23:32:55 reyk Exp $ */
+/* $OpenBSD: ieee80211_radiotap.h,v 1.5 2005/01/07 16:28:38 reyk Exp $ */
 /* $FreeBSD: src/sys/net80211/ieee80211_radiotap.h,v 1.3 2004/04/05 22:13:21 sam Exp $ */
 /* $NetBSD: ieee80211_radiotap.h,v 1.9 2004/06/06 04:13:28 dyoung Exp $ */
 
@@ -47,11 +47,6 @@
  * function of...") that I cannot set false expectations for lawyerly
  * readers.
  */
-#ifdef _KERNEL
-#ifndef DLT_IEEE802_11_RADIO
-#define	DLT_IEEE802_11_RADIO	127	/* 802.11 plus WLAN header */
-#endif
-#endif /* _KERNEL */
 
 /* XXX tcpdump/libpcap do not tolerate variable-length headers,
  * yet, so we pad every radiotap header to 64 bytes. Ugh.
-- 
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