devip: cache arp entry in Routehint

Instead of having to do an arp hash table lookup for each
outgoing ip packet, forward the Routehint pointer to the
medium's bwrite() function and let it cache the arp entry
pointer.

This avoids route and arp hash table lookups for tcp, il
and connection oriented udp.

It also allows us to avoid multiple route and arp table
lookups for the retransmits once an arp/neighbour solicitation
response arrives.

1 files changed, 16 insertions, 15 deletions

diff --git a/sys/src/9/ip/ethermedium.c b/sys/src/9/ip/ethermedium.c
index 964b71a72..fb6d05279 100644
--- a/sys/src/9/ip/ethermedium.c
+++ b/sys/src/9/ip/ethermedium.c
@@ -21,12 +21,12 @@ static void	etherread4(void *a);
 static void	etherread6(void *a);
 static void	etherbind(Ipifc *ifc, int argc, char **argv);
 static void	etherunbind(Ipifc *ifc);
-static void	etherbwrite(Ipifc *ifc, Block *bp, int version, uchar *ip);
+static void	etherbwrite(Ipifc *ifc, Block *bp, int version, uchar *ip, Routehint *rh);
 static void	etheraddmulti(Ipifc *ifc, uchar *a, uchar *ia);
 static void	etherremmulti(Ipifc *ifc, uchar *a, uchar *ia);
 static void	etherareg(Fs *f, Ipifc *ifc, Iplifc *lifc, uchar *ip);
-static Block*	multicastarp(Fs *f, Arpent *a, Medium*, uchar *mac);
-static void	sendarpreq(Ipifc *ifc, Arpent *a);
+static Block*	multicastarp(Fs *f, Arpent *a, uchar *mac, Routehint *rh);
+static void	sendarpreq(Fs *f, Arpent *a);
 static int	multicastea(uchar *ea, uchar *ip);
 static void	recvarpproc(void*);
 static void	etherpref2addr(uchar *pref, uchar *ea);
@@ -253,7 +253,7 @@ etherunbind(Ipifc *ifc)
  *  called by ipoput with a single block to write with ifc rlock'd
  */
 static void
-etherbwrite(Ipifc *ifc, Block *bp, int version, uchar *ip)
+etherbwrite(Ipifc *ifc, Block *bp, int version, uchar *ip, Routehint *rh)
 {
 	Etherhdr *eh;
 	Arpent *a;
@@ -261,22 +261,22 @@ etherbwrite(Ipifc *ifc, Block *bp, int version, uchar *ip)
 	Etherrock *er = ifc->arg;
 
 	/* get mac address of destination */
-	a = arpget(er->f->arp, bp, version, ifc, ip, mac);
+	a = arpget(er->f->arp, bp, version, ifc, ip, mac, rh);
 	if(a != nil){
 		/* check for broadcast or multicast */
-		bp = multicastarp(er->f, a, ifc->m, mac);
+		bp = multicastarp(er->f, a, mac, rh);
 		if(bp == nil){
 			/* don't do anything if it's been less than a second since the last */
 			if(a->utime - a->ctime < RETRANS_TIMER){
-				arprelease(er->f->arp, a);
+				arprelease(er->f->arp, a);	/* unlocks arp */
 				return;
 			}
 			switch(version){
 			case V4:
-				sendarpreq(ifc, a);		/* unlocks arp */
+				sendarpreq(er->f, a);	/* unlocks arp */
 				break;
 			case V6:
-				ndpsendsol(er->f, ifc, a);	/* unlocks arp */
+				ndpsendsol(er->f, a);	/* unlocks arp */
 				break;
 			default:
 				panic("etherbwrite: version %d", version);
@@ -440,16 +440,17 @@ etherremmulti(Ipifc *ifc, uchar *a, uchar *)
  *  (only v4, v6 uses the neighbor discovery, rfc1970)
  */
 static void
-sendarpreq(Ipifc *ifc, Arpent *a)
+sendarpreq(Fs *f, Arpent *a)
 {
 	int n;
 	Block *bp;
 	Etherarp *e;
+	Ipifc *ifc = a->ifc;
 	Etherrock *er = ifc->arg;
 	uchar targ[IPv4addrlen], src[IPv4addrlen];
 
 	memmove(targ, a->ip+IPv4off, IPv4addrlen);
-	arpcontinue(er->f->arp, a);
+	arpcontinue(f->arp, a);
 
 	if(!ipv4local(ifc, src, 0, targ))
 		return;
@@ -668,19 +669,19 @@ multicastea(uchar *ea, uchar *ip)
  *  IP address.
  */
 static Block*
-multicastarp(Fs *f, Arpent *a, Medium *medium, uchar *mac)
+multicastarp(Fs *f, Arpent *a, uchar *mac, Routehint *rh)
 {
 	/* is it broadcast? */
 	if(ipforme(f, a->ip) == Rbcast){
-		memset(mac, 0xff, medium->maclen);
-		return arpresolve(f->arp, a, medium, mac);
+		memset(mac, 0xff, a->ifc->m->maclen);
+		return arpresolve(f->arp, a, mac, rh);
 	}
 
 	/* if multicast, fill in mac */
 	switch(multicastea(mac, a->ip)){
 	case V4:
 	case V6:
-		return arpresolve(f->arp, a, medium, mac);
+		return arpresolve(f->arp, a, mac, rh);
 	}
 
 	/* let arp take care of it */