userspace: run dhcpc in background forever, not through auto means

Running "ifup eth0" if eth0 is configured for dhcp would make the
client try a little while and then give up. Thus, if the dhcp server
is currently down we end up without IP address. This happens after a
power failure, if the switch reboots faster than the dhcp server.

Also, avoid ifplugd, that won't help in this case (the link is up,
so no "link up" will happen later.

This new configuration works in all cases:
     - eth0 is configured with a static address in /etc/network/interfaces
     - dhcp-driven, and link goes down and then up
     - dhcp-driven, and server not ready at boot time
     - dhcp-driven and all fine since boot time

Signed-off-by: Alessandro Rubini <rubini@gnudd.com>

userspace/rootfs_override/etc/ifplugd/ifplugd.action

@@ -19,6 +19,7 @@
 
 set -e
 
+## NOTE: wr-switch-sw doesn't run ifplugd by default any more
 if [ -z "$1" ] || [ -z "$2" ] ; then
 	echo "Wrong arguments" > /dev/stderr
 	exit 1

userspace/rootfs_override/etc/init.d/S40network

@@ -3,17 +3,15 @@
 # Start the network....
 #
 
-#MAC=`/wr/bin/get_board_mac`
-#echo "Management port MAC address: $MAC"
-#ifconfig eth0 hw ether $MAC
-#ifplugd -i eth0
-#udhcpc -n
-
 if grep -q '/ nfs' /proc/mounts; then
-	echo "Running via NFS, no ifplugd."
+	echo "Running via NFS: leaving eth0 config alone"
+	exit 0
+fi
+
+if grep -v '#' /etc/network/interfaces | grep -q 'eth0.*dhcp'; then
+    # run dhcp client in background, as ifup would run in one-shot mode
+    udhcpc -b -i eth0
 else
-	echo "Starting ifplugd..."
-	/usr/sbin/ifplugd -I -f -i eth0
-	#Pull up the interface (check static/dynamic config in /etc/network/interfaces)
-	ifup eth0
+    # ifup to use static parameters from /etc/netwrok/interfaces
+    ifup eth0
 fi