This commit does two things:

1. rt_check() cleanup:
    rt_check() is only necessary for some address families to gain access
    to the corresponding arp entry, so call it only in/near the *resolve()
    routines where it is actually used -- at the moment this is
    arpresolve(), nd6_storelladdr() (the call is embedded here),
    and atmresolve() (the call is just before atmresolve to reduce
    the number of changes).
    This change will make it a lot easier to decouple the arp table
    from the routing table.

    There is an extra call to rt_check() in if_iso88025subr.c to
    determine the routing info length. I have left it alone for
    the time being.

    The interface of arpresolve() and nd6_storelladdr() now changes slightly:
     + the 'rtentry' parameter (really a hint from the upper level layer)
       is now passed unchanged from *_output(), so it becomes the route
       to the final destination and not to the gateway.
     + the routines will return 0 if resolution is possible, non-zero
       otherwise.
     + arpresolve() returns EWOULDBLOCK in case the mbuf is being held
       waiting for an arp reply -- in this case the error code is masked
       in the caller so the upper layer protocol will not see a failure.

2. arpcom untangling
    Where possible, use 'struct ifnet' instead of 'struct arpcom' variables,
    and use the IFP2AC macro to access arpcom fields.
    This mostly affects the netatalk code.

=== Detailed changes: ===
net/if_arcsubr.c
   rt_check() cleanup, remove a useless variable

net/if_atmsubr.c
   rt_check() cleanup

net/if_ethersubr.c
   rt_check() cleanup, arpcom untangling

net/if_fddisubr.c
   rt_check() cleanup, arpcom untangling

net/if_iso88025subr.c
   rt_check() cleanup

netatalk/aarp.c
   arpcom untangling, remove a block of duplicated code

netatalk/at_extern.h
   arpcom untangling

netinet/if_ether.c
   rt_check() cleanup (change arpresolve)

netinet6/nd6.c
   rt_check() cleanup (change nd6_storelladdr)

1 files changed, 28 insertions, 7 deletions

diff --git a/sys/netinet/if_ether.c b/sys/netinet/if_ether.c
index 4c91522..1bdc1fb 100644
--- a/sys/netinet/if_ether.c
+++ b/sys/netinet/if_ether.c
@@ -341,21 +341,42 @@ arprequest(ifp, sip, tip, enaddr)
  * that desten has been filled in and the packet should be sent
  * normally; a 0 return indicates that the packet has been
  * taken over here, either now or for later transmission.
+ *
+ * NEW COMMENT
+ * Resolve an IP address into an ethernet address.
+ * On input:
+ *    ifp is the interface we use
+ *    dst is the next hop,
+ *    rt0 is the route to the final destination (possibly useless)
+ *    m is the mbuf
+ *    desten is where we want the address.
+ *
+ * On success, desten is filled in and the function returns 0;
+ * If the packet must be held pending resolution, we return EWOULDBLOCK
+ * On other errors, we return the corresponding error code.
  */
 int
-arpresolve(struct ifnet *ifp, struct rtentry *rt, struct mbuf *m,
+arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
 	struct sockaddr *dst, u_char *desten)
 {
 	struct llinfo_arp *la = 0;
 	struct sockaddr_dl *sdl;
+	int error;
+	struct rtentry *rt;
+
+	error = rt_check(&rt, &rt0, dst);
+	if (error) {
+		m_freem(m);
+		return error;
+	}
 
 	if (m->m_flags & M_BCAST) {	/* broadcast */
 		(void)memcpy(desten, ifp->if_broadcastaddr, ifp->if_addrlen);
-		return (1);
+		return (0);
 	}
 	if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {/* multicast */
 		ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
-		return(1);
+		return (0);
 	}
 	if (rt)
 		la = (struct llinfo_arp *)rt->rt_llinfo;
@@ -369,7 +390,7 @@ arpresolve(struct ifnet *ifp, struct rtentry *rt, struct mbuf *m,
 			inet_ntoa(SIN(dst)->sin_addr), la ? "la" : "",
 				rt ? "rt" : "");
 		m_freem(m);
-		return (0);
+		return (EINVAL); /* XXX */
 	}
 	sdl = SDL(rt->rt_gateway);
 	/*
@@ -393,7 +414,7 @@ arpresolve(struct ifnet *ifp, struct rtentry *rt, struct mbuf *m,
 		} 
 
 		bcopy(LLADDR(sdl), desten, sdl->sdl_alen);
-		return 1;
+		return (0);
 	}
 	/*
 	 * If ARP is disabled or static on this interface, stop.
@@ -403,7 +424,7 @@ arpresolve(struct ifnet *ifp, struct rtentry *rt, struct mbuf *m,
 	 */
 	if (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) {
 		m_freem(m);
-		return (0);
+		return (EINVAL);
 	}
 	/*
 	 * There is an arptab entry, but no ethernet address
@@ -433,7 +454,7 @@ arpresolve(struct ifnet *ifp, struct rtentry *rt, struct mbuf *m,
 		}
 		RT_UNLOCK(rt);
 	}
-	return (0);
+	return (EWOULDBLOCK);
 }
 
 /*