ND_IFINFO() cannot be NULL, use inline read-only idiom for clarity

ND_IFINFO() always points at a valid struct nd_ifinfo;  ND6_LLINFO_DELAY
checks for NULL, while other cases in nd6_llinfo_timer() dereference it
unconditionally.

Inline all three per-case read-only usages rather than having one hoisted
*ndi pointer which could be used to write.

nd6_nbr.c already uses this `ND_IFINFO(ifp)->retrans' idiom which makes it
immediately clear that data is only read.

OK bluhm

diff --git a/sys/netinet6/nd6.c b/sys/netinet6/nd6.c
index 92034b6..97c3536 100644 (file)
--- a/sys/netinet6/nd6.c
+++ b/sys/netinet6/nd6.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: nd6.c,v 1.250 2022/11/10 16:00:17 kn Exp $    */
+/*     $OpenBSD: nd6.c,v 1.251 2022/11/23 08:05:49 kn Exp $    */
 /*     $KAME: nd6.c,v 1.280 2002/06/08 19:52:07 itojun Exp $   */
 
 /*
@@ -356,20 +356,17 @@ nd6_llinfo_timer(struct rtentry *rt)
        struct llinfo_nd6 *ln = (struct llinfo_nd6 *)rt->rt_llinfo;
        struct sockaddr_in6 *dst = satosin6(rt_key(rt));
        struct ifnet *ifp;
-       struct nd_ifinfo *ndi = NULL;
 
        NET_ASSERT_LOCKED();
 
        if ((ifp = if_get(rt->rt_ifidx)) == NULL)
                return 1;
 
-       ndi = ND_IFINFO(ifp);
-
        switch (ln->ln_state) {
        case ND6_LLINFO_INCOMPLETE:
                if (ln->ln_asked < nd6_mmaxtries) {
                        ln->ln_asked++;
-                       nd6_llinfo_settimer(ln, ndi->retrans / 1000);
+                       nd6_llinfo_settimer(ln, ND_IFINFO(ifp)->retrans / 1000);
                        nd6_ns_output(ifp, NULL, &dst->sin6_addr, ln, 0);
                } else {
                        struct mbuf *m = ln->ln_hold;
@@ -413,19 +410,16 @@ nd6_llinfo_timer(struct rtentry *rt)
                break;
 
        case ND6_LLINFO_DELAY:
-               if (ndi) {
-                       /* We need NUD */
-                       ln->ln_asked = 1;
-                       ln->ln_state = ND6_LLINFO_PROBE;
-                       nd6_llinfo_settimer(ln, ndi->retrans / 1000);
-                       nd6_ns_output(ifp, &dst->sin6_addr,
-                           &dst->sin6_addr, ln, 0);
-               }
+               /* We need NUD */
+               ln->ln_asked = 1;
+               ln->ln_state = ND6_LLINFO_PROBE;
+               nd6_llinfo_settimer(ln, ND_IFINFO(ifp)->retrans / 1000);
+               nd6_ns_output(ifp, &dst->sin6_addr, &dst->sin6_addr, ln, 0);
                break;
        case ND6_LLINFO_PROBE:
                if (ln->ln_asked < nd6_umaxtries) {
                        ln->ln_asked++;
-                       nd6_llinfo_settimer(ln, ndi->retrans / 1000);
+                       nd6_llinfo_settimer(ln, ND_IFINFO(ifp)->retrans / 1000);
                        nd6_ns_output(ifp, &dst->sin6_addr,
                            &dst->sin6_addr, ln, 0);
                } else {