sync ipv6on. this was not part of any patch

Reference: /n/atom/patch/applied/ipv6onfixes
Date: Sat Mar 22 18:40:57 CET 2014
Signed-off-by: quanstro@quanstro.net

--- /rc/bin/ipv6on	Sat Mar 22 18:40:52 2014
+++ /rc/bin/ipv6on	Sat Mar 22 18:40:53 2014
@@ -1,24 +1,23 @@
 #!/bin/rc
-# ipv6on [netdir ndbfile [gwv4]] - configure an interface for ipv6,
-#	once ipv4 is configured.
+# ipv6on [netdir ndbfile] - configure an interface for ipv6.
+#	use ipv6 address from ndb if present,
+#	else do stateless address autoconfiguration (SLAAC).
 if (! ~ $#* 0 2 3) {
-	echo usage: $0 '[netdir ndbfile [gw-v4-name]]' >[1=2]
+	echo usage: $0 '[netdir ndbfile [obs-gw-v4-name]]' >[1=2]
 	exit usage
 }
 rfork e
+fn ipq {			# attr val rattr
+	ndb/ipquery $* | sed 's/^[a-z0-9]+=//'
+}
+
 if (~ $#* 0) {
 	netdir=/net
 	ndbf=/lib/ndb/local
-	gw=`{ndb/ipquery sys $sysname ipgw | sed 's/ipgw=//'}
 }
 if not {
 	netdir=$1
 	ndbf=$2
-	if (~ $#* 2)
-		# gw=()
-		gw=`{ndb/ipquery sys $sysname ipgw | sed 's/ipgw=//'}
-	if not
-		gw=$3
 }
 if (~ $netdir /net) {
 	xsfx=()
@@ -41,54 +40,33 @@
 }
 
 #
-# configure v6 for link-local addresses (fe80::) & multicast (ff02::)
+# configure v6 for link-local addresses (fe80::) & multicast (ff02::).
+# accept router advertisements, which will contain a default route.
 #
 if (! ip/ipconfig -6 $xdir ether $netdir/ether?)
 	exit 'ipconfig -6 failed'
 ip/ipconfig $xdir ether $netdir/ether? ra6 recvra 1
 
-mev6=`{ndb/query -f $ndbf sys $sysname ipv6}
-if (~ $#sysname 0 || ~ $sysname '')
-	mev6=`{ndb/query -f $ndbf sys $sysname ip | grep :}
-# mev4=`{ndb/query -f $ndbf sys $sysname ip | grep -v :}
-
-# for testing
-mylnk=`{ip/linklocal `{cat $netdir/ether?/addr}}
-nonnil mylnk
-
-if (~ $#gw 1) {
-	if (~ $gw [0-9]*.[0-9]*.[0-9]*.[0-9]*)
-		gwv4 = $gw
-	if (~ $#gwv4 0 || ~ $gwv4 '')		# assume namev6 and name
-		gwv4=`{ndb/query -f $ndbf sys $gw ip}
-	gwv6=`{ndb/query -f $ndbf sys $gw ipv6}
-
-	if (! ~ $#gwv4 0) {
-		# echo ping gw $gwv4...
-		# load arp cache with gw mac
-		ip/ping -qn 3 $netdir/icmp!$gwv4 >/dev/null >[2=1] &
-		sleep 1					# wait for ping
-
-		gweth=`{grep '* '^$gwv4^' ' $netdir/arp | awk '{print $4}' }
-		nonnil gweth >[2]/dev/null	# don't frighten users
-		gwlnk=`{ip/linklocal $gweth}
-		nonnil gwlnk >[2]/dev/null
-	}
+# lookup any v6 address for me in ndb, else use slaac
+myeth=`{cat $netdir/ether?/addr}
+mev6=`{ndb/query -f $ndbf ether $myeth ipv6}
+if (~ $#mev6 0 || ~ $mev6 '')
+	mev6=`{ndb/query -f $ndbf sys $sysname ipv6}
+if (~ $#mev6 0 || ~ $mev6 '') {
+	# slaac: could perhaps get prefix from above RA
+	ipnet=`{ipq ether $myeth ipnet}
+	if (~ $#ipnet 0 || ~ $ipnet '')
+		ipnet=`{ipq sys $sysname ipnet}
+	nonnil ipnet
+	v6pfx=`{ipq ipnet $ipnet ipv6pfx}
+	nonnil v6pfx
+	mev6=`{ip/linklocal $myeth | sed 's/^fe80:/'$v6pfx'/'}
 }
 nonnil mev6
+
 #
 # configure my global v6 addresses
 #
-ip/ipconfig $xdir ether $netdir/ether?	add $mev6 /64
+v6mask=`{ipq ip $mev6 ipmask}
+ip/ipconfig $xdir ether $netdir/ether?	add $mev6 $v6mask
 ip/ipconfig $xdir loopback /dev/null	add $mev6 /128
-
-if (~ $#gw 1) {
-	if (~ $#gwv6 0 || ~ $gwv6 '')
-		gwv6=`{ip/linklocal $gweth}
-	nonnil gwv6
-	#
-	# add default v6 route to v6 addr of v4 gw
-	#
-	echo add :: /0 $gwv6 >$netdir/iproute	# need not be link-local
-}
-exit ''