replace pointer arithmetic and casts with offsetof

ok mpi@ bluhm@

diff --git a/sys/netinet6/ip6_input.c b/sys/netinet6/ip6_input.c
index 4cfcba2..2be6e58 100644 (file)
--- a/sys/netinet6/ip6_input.c
+++ b/sys/netinet6/ip6_input.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: ip6_input.c,v 1.148 2015/10/19 12:11:28 mpi Exp $     */
+/*     $OpenBSD: ip6_input.c,v 1.149 2015/10/23 00:15:07 jsg Exp $     */
 /*     $KAME: ip6_input.c,v 1.188 2001/03/29 05:34:31 itojun Exp $     */
 
 /*
@@ -634,7 +634,7 @@ ip6_input(struct mbuf *m)
                                ip6 = mtod(m, struct ip6_hdr *);
                                icmp6_error(m, ICMP6_DST_UNREACH,
                                        ICMP6_DST_UNREACH_ADDR,
-                                       (caddr_t)&ip6->ip6_dst - (caddr_t)ip6);
+                                       offsetof(struct ip6_hdr, ip6_dst));
                                break;
                        } else
                                goto bad;