Back in the old cool days you could simply call ether_output() with a
stuffed sockaddr and it will do the L2 resolution for you... Well as
long as you do not care about IPv6 it's true.
During the last years I tried to reduce the number of places where
ether_output() was called without passing it a "struct rtentry" as
last argument. The reason for this move is to remove a potential
route insertion in arpresolve(), done in read-only context (hot path).
Diff below convert the last offender explicitly passing NULL to an
if_output() function: pf_route().
I'm interested in tests but keep in mind that it is highly probable
that some code paths still path a NULL pointer as last argument, if
rtalloc(9) fails and its return is not checked. That's why I added
a KASSERT(), to fix these cases.
Index: net/if_ethersubr.c
===================================================================
RCS file: /cvs/src/sys/net/if_ethersubr.c,v
retrieving revision 1.236
diff -u -p -r1.236 if_ethersubr.c
--- net/if_ethersubr.c 18 May 2016 20:15:14 -0000 1.236
+++ net/if_ethersubr.c 18 May 2016 20:45:47 -0000
@@ -193,8 +193,12 @@ ether_output(struct ifnet *ifp, struct m
struct mbuf *mcopy = NULL;
struct ether_header *eh;
struct arpcom *ac = (struct arpcom *)ifp;
+ sa_family_t af = dst->sa_family;
int error = 0;
+ KASSERT(rt != NULL || ISSET(m->m_flags, M_MCAST|M_BCAST) ||
+ af == AF_UNSPEC || af == pseudo_AF_HDRCMPLT);
+
#ifdef DIAGNOSTIC
if (ifp->if_rdomain != rtable_l2(m->m_pkthdr.ph_rtableid)) {
printf("%s: trying to send packet on wrong domain. "
@@ -208,7 +212,7 @@ ether_output(struct ifnet *ifp, struct m
if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
senderr(ENETDOWN);
- switch (dst->sa_family) {
+ switch (af) {
case AF_INET:
error = arpresolve(ifp, rt, m, dst, edst);
if (error)
Index: net/pf.c
===================================================================
RCS file: /cvs/src/sys/net/pf.c,v
retrieving revision 1.970
diff -u -p -r1.970 pf.c
--- net/pf.c 3 May 2016 12:13:38 -0000 1.970
+++ net/pf.c 18 May 2016 20:45:49 -0000
@@ -5574,6 +5574,12 @@ pf_route(struct mbuf **m, struct pf_rule
s->rt_addr.v4.s_addr;
ifp = s->rt_kif ? s->rt_kif->pfik_ifp : NULL;
}
+
+ rt = rtalloc(sintosa(dst), RT_RESOLVE, rtableid);
+ if (rt == NULL) {
+ ipstat.ips_noroute++;
+ goto bad;
+ }
}
if (ifp == NULL)
goto bad;
@@ -5602,7 +5608,7 @@ pf_route(struct mbuf **m, struct pf_rule
ipstat.ips_outswcsum++;
ip->ip_sum = in_cksum(m0, ip->ip_hl << 2);
}
- error = ifp->if_output(ifp, m0, sintosa(dst), NULL);
+ error = ifp->if_output(ifp, m0, sintosa(dst), rt);
goto done;
}
@@ -5631,7 +5637,7 @@ pf_route(struct mbuf **m, struct pf_rule
m1 = m0->m_nextpkt;
m0->m_nextpkt = 0;
if (error == 0)
- error = ifp->if_output(ifp, m0, sintosa(dst), NULL);
+ error = ifp->if_output(ifp, m0, sintosa(dst), rt);
else
m_freem(m0);
}
Index: netinet/if_ether.c
===================================================================
RCS file: /cvs/src/sys/netinet/if_ether.c,v
retrieving revision 1.207
diff -u -p -r1.207 if_ether.c
--- netinet/if_ether.c 18 May 2016 20:15:14 -0000 1.207
+++ netinet/if_ether.c 18 May 2016 20:45:50 -0000
@@ -294,40 +294,28 @@ arpresolve(struct ifnet *ifp, struct rte
return (0);
}
- if (rt0 != NULL) {
- error = rt_checkgate(rt0, &rt);
- if (error) {
- m_freem(m);
- return (error);
- }
+ error = rt_checkgate(rt0, &rt);
+ if (error) {
+ m_freem(m);
+ return (error);
+ }
- if ((rt->rt_flags & RTF_LLINFO) == 0) {
- log(LOG_DEBUG, "%s: %s: route contains no arp"
- " information\n", __func__, inet_ntop(AF_INET,
- &satosin(rt_key(rt))->sin_addr, addr,
- sizeof(addr)));
- m_freem(m);
- return (EINVAL);
- }
+ if ((rt->rt_flags & RTF_LLINFO) == 0) {
+ log(LOG_DEBUG, "%s: %s: route contains no arp"
+ " information\n", __func__, inet_ntop(AF_INET,
+ &satosin(rt_key(rt))->sin_addr, addr,
+ sizeof(addr)));
+ m_freem(m);
+ return (EINVAL);
+ }
- la = (struct llinfo_arp *)rt->rt_llinfo;
- if (la == NULL)
- log(LOG_DEBUG, "%s: %s: route without link "
- "local address\n", __func__, inet_ntop(AF_INET,
- &satosin(dst)->sin_addr, addr, sizeof(addr)));
- } else {
- rt = arplookup(satosin(dst)->sin_addr.s_addr, 1, 0,
- ifp->if_rdomain);
- if (rt != NULL) {
- created = 1;
- la = ((struct llinfo_arp *)rt->rt_llinfo);
- }
- if (la == NULL)
- log(LOG_DEBUG, "%s: %s: can't allocate llinfo\n",
- __func__,
- inet_ntop(AF_INET, &satosin(dst)->sin_addr,
- addr, sizeof(addr)));
+ la = (struct llinfo_arp *)rt->rt_llinfo;
+ if (la == NULL) {
+ inet_ntop(AF_INET, &satosin(dst)->sin_addr, addr, sizeof(addr));
+ log(LOG_DEBUG, "%s: %s: route without link local address\n",
+ __func__, addr);
}
+
if (la == NULL || rt == NULL)
goto bad;
sdl = satosdl(rt->rt_gateway);
Index: netinet6/nd6.c
===================================================================
RCS file: /cvs/src/sys/netinet6/nd6.c,v
retrieving revision 1.179
diff -u -p -r1.179 nd6.c
--- netinet6/nd6.c 17 May 2016 08:29:14 -0000 1.179
+++ netinet6/nd6.c 18 May 2016 20:45:50 -0000
@@ -1667,12 +1667,6 @@ nd6_storelladdr(struct ifnet *ifp, struc
}
}
- if (rt0 == NULL) {
- /* this could happen, if we could not allocate memory */
- m_freem(m);
- return (ENOMEM);
- }
-
error = rt_checkgate(rt0, &rt);
if (error) {
m_freem(m);
