mark the program and buffer as const in bpf_filter()

other projects have already done this, and there's software (eg,
gopacket) which now expects it.

based on a discussion with jasper@ and canacar@
ok jasper@

2 files changed, 5 insertions, 4 deletions

diff --git a/sys/net/bpf.h b/sys/net/bpf.h
index 37887894867..27c676828e7 100644
--- a/sys/net/bpf.h
+++ b/sys/net/bpf.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bpf.h,v 1.53 2016/04/02 08:49:49 dlg Exp $	*/
+/*	$OpenBSD: bpf.h,v 1.54 2016/04/02 09:05:16 dlg Exp $	*/
 /*	$NetBSD: bpf.h,v 1.15 1996/12/13 07:57:33 mikel Exp $	*/
 
 /*
@@ -277,7 +277,7 @@ struct bpf_ops {
 #define BPF_STMT(code, k) { (u_int16_t)(code), 0, 0, k }
 #define BPF_JUMP(code, k, jt, jf) { (u_int16_t)(code), jt, jf, k }
 
-u_int	 bpf_filter(struct bpf_insn *, u_char *, u_int, u_int);
+u_int	 bpf_filter(const struct bpf_insn *, const u_char *, u_int, u_int);
 
 u_int	 _bpf_filter(const struct bpf_insn *, const struct bpf_ops *,
 	     const void *, u_int);
diff --git a/sys/net/bpf_filter.c b/sys/net/bpf_filter.c
index 081d1592fd5..61418d652da 100644
--- a/sys/net/bpf_filter.c
+++ b/sys/net/bpf_filter.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bpf_filter.c,v 1.28 2016/04/02 08:49:49 dlg Exp $	*/
+/*	$OpenBSD: bpf_filter.c,v 1.29 2016/04/02 09:05:16 dlg Exp $	*/
 /*	$NetBSD: bpf_filter.c,v 1.12 1996/02/13 22:00:00 christos Exp $	*/
 
 /*
@@ -125,7 +125,8 @@ bpf_mem_ldb(const void *mem, u_int32_t k, int *err)
  * buflen is the amount of data present
  */
 u_int
-bpf_filter(struct bpf_insn *pc, u_char *pkt, u_int wirelen, u_int buflen)
+bpf_filter(const struct bpf_insn *pc, const u_char *pkt,
+    u_int wirelen, u_int buflen)
 {
 	struct bpf_mem bm;