ThirdPartyVpn hierarchy
=======================

Service		org.chromium.flimflam
Interface	org.chromium.flimflam.ThirdPartyVpn
Object path	/thirdpartyvpn/{objectpath0,objectpath1,...}

Methods		string SetParameters(dict parameters)

			Configures the VPN's IP parameters.  This should
			be called after receiving a Connected, LinkChanged,
			or LinkUp platform message.  See below for the list
			of parameters.

			Returns an error message on failure, or "" on
			success.

		void UpdateConnectionState(uint32 connection_state)

			Informs shill of the VPN app's connection state,
			so that it can set the correct service state.

			Possible values:

				1 (kStateConnected) - The VPN app is now
				  online, so shill should use it to pass
				  system traffic.
				2 (kStateFailure) - The VPN app has failed
				  to connect (or reconnect) so the service
				  should be disabled.

		void SendPacket(array{uint8} ip_packet)

			Transmits an IP packet to the tunnel interface.
			This packet should not have an Ethernet header.

Signals		OnPlatformMessage(uint32 platform_message)

			Informs a VPN app of changes to the network
			configuration.

			Possible values:

				1 (kConnected) - The app can now call
				  SetParameters to configure the tunnel.
				2 (kDisconnected) - A "clean" disconnection
				  has taken place, and the service will no
				  longer pass traffic.
				3 (kError) - An "unclean" disconnection has
				  taken place, and the service will no
				  longer pass traffic.
				4 (kLinkDown) - The system's physical
				  network connection has gone down, so
				  the VPN app will not have connectivity.
				5 (kLinkUp) - The system's physical network
				  connection has been restored.
				6 (kLinkChanged) - The system's physical
				  network connection has changed, and the
				  VPN may need to reconnect to the gateway.
				7 (kSuspend) - The system is going to sleep.
				8 (kResume) - The system has woken up from
				  sleep.

		OnPacketReceived(array{uint8} ip_packet)

			A packet has been received from the tunnel
			interface.  This packet will not have an Ethernet
			header.

Parameters	string address [mandatory]

			An IPv4 address, e.g. "192.168.1.1"

		string subnet_prefix [mandatory]

			The IPv4 subnet prefix length, typically "32"

		string broadcast_address [optional]

			An IPv4 address, e.g. "192.168.1.255"

		string exclusion_list [mandatory, but may be empty]

			A comma-separated list of IPv4 ranges in CIDR
			notation that should be excluded from the VPN
			tunnel.  e.g. "8.8.8.8/32,192.168.2.0/24"

		string inclusion_list [mandatory, but may be empty]

			A comma-separated list of IPv4 ranges in CIDR
			notation that should be routed through the VPN
			tunnel.  e.g. "192.168.1.0/24,10.0.0.0/8"

		string dns_servers [optional]

			A comma-separated list of IPv4 addresses used for
			DNS servers.

		string domain_search [optional]

			A comma-separated list of DNS search domains.

		string mtu [optional]

			The MTU for the tunnel interface.  e.g. "1280"

			The default is 1500 bytes.

		string reconnect [optional]

			Indicates whether the VPN app can handle LinkDown,
			LinkUp, LinkChanged, Suspend, and Resume events.
			If not, the service will disconnect if the system's
			physical network changes.

			Possible values:

				"true" - Reconnections are supported.
				"false" - Reconnections are not supported.

			The default is "false".