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)

5 files changed, 43 insertions, 61 deletions

diff --git a/sys/net/if_arcsubr.c b/sys/net/if_arcsubr.c
index 47d7b5c..b4aa519 100644
--- a/sys/net/if_arcsubr.c
+++ b/sys/net/if_arcsubr.c
@@ -107,8 +107,6 @@ arc_output(ifp, m, dst, rt0)
 	struct sockaddr *dst;
 	struct rtentry *rt0;
 {
-	struct rtentry		*rt;
-	struct arccom		*ac;
 	struct arc_header	*ah;
 	int			error;
 	u_int8_t		atype, adst;
@@ -119,11 +117,6 @@ arc_output(ifp, m, dst, rt0)
 		return(ENETDOWN); /* m, m1 aren't initialized yet */
 
 	error = 0;
-	ac = (struct arccom *)ifp;
-
-	error = rt_check(&rt, &rt0, dst);
-	if (error)
-		goto bad;
 
 	switch (dst->sa_family) {
 #ifdef INET
@@ -136,8 +129,11 @@ arc_output(ifp, m, dst, rt0)
 			adst = arcbroadcastaddr; /* ARCnet broadcast address */
 		else if (ifp->if_flags & IFF_NOARP)
 			adst = ntohl(SIN(dst)->sin_addr.s_addr) & 0xFF;
-		else if (!arpresolve(ifp, rt, m, dst, &adst))
-			return 0;	/* not resolved yet */
+		else {
+			error = arpresolve(ifp, rt0, m, dst, &adst);
+			if (error)
+				return (error == EWOULDBLOCK ? 0 : error);
+		}
 
 		atype = (ifp->if_flags & IFF_LINK0) ?
 			ARCTYPE_IP_OLD : ARCTYPE_IP;
@@ -172,13 +168,9 @@ arc_output(ifp, m, dst, rt0)
 #endif
 #ifdef INET6
 	case AF_INET6:
-#ifdef OLDIP6OUTPUT
-		if (!nd6_resolve(ifp, rt, m, dst, (u_char *)&adst))
-			return(0);	/* if not yet resolves */
-#else
-		if (!nd6_storelladdr(ifp, rt, m, dst, (u_char *)&adst))
-			return(0); /* it must be impossible, but... */
-#endif /* OLDIP6OUTPUT */
+		error = nd6_storelladdr(ifp, rt0, m, dst, (u_char *)&adst);
+		if (error)
+			return (error);
 		atype = ARCTYPE_INET6;
 		break;
 #endif
diff --git a/sys/net/if_atmsubr.c b/sys/net/if_atmsubr.c
index f404984..e7df9c3 100644
--- a/sys/net/if_atmsubr.c
+++ b/sys/net/if_atmsubr.c
@@ -126,7 +126,6 @@ atm_output(struct ifnet *ifp, struct mbuf *m0, struct sockaddr *dst,
 	int error = 0, sz;
 	struct atm_pseudohdr atmdst, *ad;
 	struct mbuf *m = m0;
-	struct rtentry *rt;
 	struct atmllc *atmllc;
 	struct atmllc *llc_hdr = NULL;
 	u_int32_t atm_flags;
@@ -141,13 +140,6 @@ atm_output(struct ifnet *ifp, struct mbuf *m0, struct sockaddr *dst,
 		senderr(ENETDOWN);
 
 	/*
-	 * check route
-	 */
-	error = rt_check(&rt, &rt0, dst);
-	if (error)
-		goto bad;
-
-	/*
 	 * check for non-native ATM traffic   (dst != NULL)
 	 */
 	if (dst) {
@@ -156,6 +148,15 @@ atm_output(struct ifnet *ifp, struct mbuf *m0, struct sockaddr *dst,
 #if defined(INET) || defined(INET6)
 		case AF_INET:
 		case AF_INET6:
+		{
+			struct rtentry *rt;
+			/*  
+			 * check route
+			 */
+			error = rt_check(&rt, &rt0, dst);
+			if (error)
+				goto bad;
+
 			if (dst->sa_family == AF_INET6)
 			        etype = ETHERTYPE_IPV6;
 			else
@@ -167,6 +168,7 @@ atm_output(struct ifnet *ifp, struct mbuf *m0, struct sockaddr *dst,
 				/* XXX: put ATMARP stuff here */
 				/* XXX: watch who frees m on failure */
 			}
+		}
 			break;
 #endif /* INET || INET6 */
 
diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c
index ae59947..47ba291 100644
--- a/sys/net/if_ethersubr.c
+++ b/sys/net/if_ethersubr.c
@@ -132,9 +132,8 @@ ether_output(struct ifnet *ifp, struct mbuf *m,
 	struct sockaddr *dst, struct rtentry *rt0)
 {
 	short type;
-	int error = 0, hdrcmplt = 0;
+	int error, hdrcmplt = 0;
 	u_char esrc[ETHER_ADDR_LEN], edst[ETHER_ADDR_LEN];
-	struct rtentry *rt;
 	struct ether_header *eh;
 	int loop_copy = 0;
 	int hlen;	/* link layer header length */
@@ -150,16 +149,13 @@ ether_output(struct ifnet *ifp, struct mbuf *m,
 	if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
 		senderr(ENETDOWN);
 
-	error = rt_check(&rt, &rt0, dst);
-	if (error)
-		goto bad;
-
 	hlen = ETHER_HDR_LEN;
 	switch (dst->sa_family) {
 #ifdef INET
 	case AF_INET:
-		if (!arpresolve(ifp, rt, m, dst, edst))
-			return (0);	/* if not yet resolved */
+		error = arpresolve(ifp, rt0, m, dst, edst);
+		if (error)
+			return (error == EWOULDBLOCK ? 0 : error);
 		type = htons(ETHERTYPE_IP);
 		break;
 	case AF_ARP:
@@ -192,10 +188,9 @@ ether_output(struct ifnet *ifp, struct mbuf *m,
 #endif
 #ifdef INET6
 	case AF_INET6:
-		if (!nd6_storelladdr(ifp, rt, m, dst, (u_char *)edst)) {
-			/* Something bad happened */
-			return(0);
-		}
+		error = nd6_storelladdr(ifp, rt0, m, dst, (u_char *)edst);
+		if (error)
+			return error;
 		type = htons(ETHERTYPE_IPV6);
 		break;
 #endif
@@ -216,15 +211,12 @@ ether_output(struct ifnet *ifp, struct mbuf *m,
 	  {
 	    struct at_ifaddr *aa;
 
-	    if ((aa = at_ifawithnet((struct sockaddr_at *)dst)) == NULL) {
-		    goto bad;
-	    }
-	    if (!aarpresolve(IFP2AC(ifp), m, (struct sockaddr_at *)dst, edst))
+	    if ((aa = at_ifawithnet((struct sockaddr_at *)dst)) == NULL)
+		    senderr(EHOSTUNREACH); /* XXX */
+	    if (!aarpresolve(ifp, m, (struct sockaddr_at *)dst, edst))
 		    return (0);
 	    /*
 	     * In the phase 2 case, need to prepend an mbuf for the llc header.
-	     * Since we must preserve the value of m, which is passed to us by
-	     * value, we m_copy() the first mbuf, and use it for our llc header.
 	     */
 	    if ( aa->aa_flags & AFA_PHASE2 ) {
 		struct llc llc;
diff --git a/sys/net/if_fddisubr.c b/sys/net/if_fddisubr.c
index d9330ee5..47bf0c3 100644
--- a/sys/net/if_fddisubr.c
+++ b/sys/net/if_fddisubr.c
@@ -117,7 +117,6 @@ fddi_output(ifp, m, dst, rt0)
 	u_int16_t type;
 	int loop_copy = 0, error = 0, hdrcmplt = 0;
  	u_char esrc[FDDI_ADDR_LEN], edst[FDDI_ADDR_LEN];
-	struct rtentry *rt;
 	struct fddi_header *fh;
 
 #ifdef MAC
@@ -132,15 +131,12 @@ fddi_output(ifp, m, dst, rt0)
 		senderr(ENETDOWN);
 	getmicrotime(&ifp->if_lastchange);
 
-	error = rt_check(&rt, &rt0, dst);
-	if (error)
-		goto bad;
-
 	switch (dst->sa_family) {
 #ifdef INET
 	case AF_INET: {
-		if (!arpresolve(ifp, rt, m, dst, edst))
-			return (0);	/* if not yet resolved */
+		error = arpresolve(ifp, rt0, m, dst, edst);
+		if (error)
+			return (error == EWOULDBLOCK ? 0 : error);
 		type = htons(ETHERTYPE_IP);
 		break;
 	}
@@ -174,10 +170,9 @@ fddi_output(ifp, m, dst, rt0)
 #endif /* INET */
 #ifdef INET6
 	case AF_INET6:
-		if (!nd6_storelladdr(ifp, rt, m, dst, (u_char *)edst)) {
-			/* Something bad happened */
-			return (0);
-		}
+		error = nd6_storelladdr(ifp, rt0, m, dst, (u_char *)edst);
+		if (error)
+			return (error); /* Something bad happened */
 		type = htons(ETHERTYPE_IPV6);
 		break;
 #endif /* INET6 */
@@ -191,7 +186,7 @@ fddi_output(ifp, m, dst, rt0)
 #ifdef NETATALK
 	case AF_APPLETALK: {
 	    struct at_ifaddr *aa;
-            if (!aarpresolve(IFP2AC(ifp), m, (struct sockaddr_at *)dst, edst))
+            if (!aarpresolve(ifp, m, (struct sockaddr_at *)dst, edst))
                 return (0);
 	    /*
 	     * ifaddr is the first thing in at_ifaddr
diff --git a/sys/net/if_iso88025subr.c b/sys/net/if_iso88025subr.c
index 72b246f..a34f929 100644
--- a/sys/net/if_iso88025subr.c
+++ b/sys/net/if_iso88025subr.c
@@ -259,11 +259,12 @@ iso88025_output(ifp, m, dst, rt0)
 		senderr(ENETDOWN);
 	getmicrotime(&ifp->if_lastchange);
 
+	/* Calculate routing info length based on arp table entry */
+	/* XXX any better way to do this ? */
 	error = rt_check(&rt, &rt0, dst);
 	if (error)
 		goto bad;
 
-	/* Calculate routing info length based on arp table entry */
 	if (rt && (sdl = (struct sockaddr_dl *)rt->rt_gateway))
 		if (SDL_ISO88025(sdl)->trld_rcf != 0)
 			rif_len = TR_RCF_RIFLEN(SDL_ISO88025(sdl)->trld_rcf);
@@ -286,8 +287,9 @@ iso88025_output(ifp, m, dst, rt0)
 	switch (dst->sa_family) {
 #ifdef INET
 	case AF_INET:
-		if (!arpresolve(ifp, rt, m, dst, edst))
-			return (0);	/* if not yet resolved */
+		error = arpresolve(ifp, rt0, m, dst, edst);
+		if (error)
+			return (error == EWOULDBLOCK ? 0 : error);
 		snap_type = ETHERTYPE_IP;
 		break;
 	case AF_ARP:
@@ -320,10 +322,9 @@ iso88025_output(ifp, m, dst, rt0)
 #endif	/* INET */
 #ifdef INET6
 	case AF_INET6:
-		if (!nd6_storelladdr(ifp, rt, m, dst, (u_char *)edst)) {
-			/* Something bad happened */
-			return(0);
-		}
+		error = nd6_storelladdr(ifp, rt0, m, dst, (u_char *)edst);
+		if (error)
+			return (error);
 		snap_type = ETHERTYPE_IPV6;
 		break;
 #endif	/* INET6 */