net-online: updates to make the service more usable

- switch from attempting to ping the default gateway to a host outside
the local network, defaulting to google.com.
- along with this, change the name of the variable that requests a ping
test to include_ping_test so the meaning is more clear.

conf.d/net-online

@@ -3,10 +3,13 @@
 # default is all interfaces that support ethernet.
 #interfaces=""
 
-# This setting controls whether a ping to the default gateway is
-# included in the test for network connectivity after all interfaces
-# are active.
-#ping_default_gateway=no
+# This setting controls whether a ping test is included in the test for
+# network connectivity after all interfaces are active.
+#include_ping_test=no
+
+# This setting is the host to attempt to ping if the above is yes.
+# The default is google.com.
+#ping_test_host=some.host.name
 
 # The timeout setting controls how long the net-online service waits
 # for the network to be configured.

init.d/net-online.in

@@ -15,6 +15,7 @@ depend()
 {
 	after modules
 	need sysfs
+	provide network-online
 	keyword -docker -jail -lxc -openvz -prefix -systemd-nspawn -uml -vserver
 }
 
@@ -27,19 +28,6 @@ get_interfaces()
 	done
 }
 
-get_default_gateway()
-{
-	local cmd gateway
-	if command -v ip > /dev/null 2>&1; then
-		cmd="ip route show"
-	else
-		cmd=route
-	fi
-	set -- $($cmd | grep default)
-	[ "$2" != via ] && gateway="$2" || gateway="$3"
-	printf "%s" $gateway
-}
-
 start ()
 {
 	local carriers configured dev gateway ifcount infinite
@@ -66,10 +54,15 @@ start ()
 	: $((timeout -= 1))
  done
  ! $infinite && [ $timeout -eq 0 ] && rc=1
- if [ $rc -eq 0 ] && yesno ${ping_default_gateway:-no}; then
- 	gateway="$(get_default_gateway)"
- 	if [ -n "$gateway" ] && ! ping -c 1 $gateway > /dev/null 2>&1; then
-		rc=1
+ include_ping_test=${include_ping_test:-${ping_default_gateway}}
+ if [ -n "${ping_default_gateway}" ]; then
+ ewarn "ping_default_gateway is deprecated, please use include_ping_test'
+ fi
+ if [ $rc -eq 0 ] && yesno ${include_ping_test:-no}; then
+ 	ping_test_host="${ping_test_host:-google.com}"
+ 	if [ -n "$ping_test_host" ]; then
+		ping -c 1 $ping_test_host > /dev/null 2>&1
+		rc=$?
 	fi
  fi
  eend $rc "The network is offline"