1 files changed, 85 insertions, 20 deletions
diff --git a/src/Propellor/Property/Network.hs b/src/Propellor/Property/Network.hs
index 6009778a..4d7ccffb 100644
--- a/src/Propellor/Property/Network.hs
+++ b/src/Propellor/Property/Network.hs
@@ -3,28 +3,93 @@ module Propellor.Property.Network where
 import Propellor
 import Propellor.Property.File
 
-interfaces :: FilePath
-interfaces = "/etc/network/interfaces"
+type Interface = String
+
+ifUp :: Interface -> Property NoInfo
+ifUp iface = cmdProperty "ifup" [iface]
+
+-- | Resets /etc/network/interfaces to a clean and empty state,
+-- containing just the standard loopback interface, and with
+-- interfacesD enabled.
+--
+-- This can be used as a starting point to defining other interfaces.
+--
+-- No interfaces are brought up or down by this property.
+cleanInterfacesFile :: Property NoInfo
+cleanInterfacesFile = hasContent interfacesFile
+	[ "# Deployed by propellor, do not edit."
+	, ""
+	, "source-directory interfaces.d"
+	, ""
+	, "# The loopback network interface"
+	, "auto lo"
+	, "iface lo inet loopback"
+	]
+	`describe` ("clean " ++ interfacesFile)
+
+-- | Writes a static interface file for the specified interface.
+--
+-- The interface has to be up already. It could have been brought up by
+-- DHCP, or by other means. The current ipv4 addresses
+-- and routing configuration of the interface are written into the file.
+--
+-- If the interface file already exists, this property does nothing,
+-- no matter its content.
+-- 
+-- (ipv6 addresses are not included because it's assumed they come up
+-- automatically in most situations.)
+static :: Interface -> Property NoInfo
+static iface = check (not <$> doesFileExist f) setup
+	`describe` desc
+	`requires` interfacesDEnabled
+  where
+	f = interfaceDFile iface
+	desc = "static " ++ iface
+	setup = property desc $ do
+		ls <- liftIO $ lines <$> readProcess "ip"
+			["-o", "addr", "show", iface, "scope", "global"]
+		stanzas <- liftIO $ concat <$> mapM mkstanza ls
+		ensureProperty $ hasContent f $ ("auto " ++ iface) : stanzas
+	mkstanza ipline = case words ipline of
+		-- Note that the IP address is written CIDR style, so
+		-- the netmask does not need to be specified separately.
+		(_:iface':"inet":addr:_) | iface' == iface -> do
+			gw <- getgateway
+			return $ catMaybes
+				[ Just $ "iface " ++ iface ++ " inet static"
+				, Just $ "\taddress " ++ addr
+				, ("\tgateway " ++) <$> gw
+				]
+		_ -> return []
+	getgateway = do
+		rs <- lines <$> readProcess "ip"
+			["route", "show", "scope", "global", "dev", iface]
+		return $ case words <$> headMaybe rs of
+			Just ("default":"via":gw:_) -> Just gw
+			_ -> Nothing
 
 -- | 6to4 ipv6 connection, should work anywhere
-ipv6to4 :: Property
-ipv6to4 = fileProperty "ipv6to4" go interfaces
+ipv6to4 :: Property NoInfo
+ipv6to4 = hasContent (interfaceDFile "sit0")
+	[ "# Deployed by propellor, do not edit."
+	, "iface sit0 inet6 static"
+	, "\taddress 2002:5044:5531::1"
+	, "\tnetmask 64"
+	, "\tgateway ::192.88.99.1"
+	, "auto sit0"
+	]
+	`describe` "ipv6to4"
+	`requires` interfacesDEnabled
 	`onChange` ifUp "sit0"
-  where
-	go ls
-		| all (`elem` ls) stanza = ls
-		| otherwise = ls ++ stanza
-	stanza =
-		[ "# Automatically added by propeller"
-		, "iface sit0 inet6 static"
-		, "\taddress 2002:5044:5531::1"
-		, "\tnetmask 64"
-		, "\tgateway ::192.88.99.1"
-		, "auto sit0"
-		, "# End automatically added by propeller"
-		]
 
-type Interface = String
+interfacesFile :: FilePath
+interfacesFile = "/etc/network/interfaces"
 
-ifUp :: Interface -> Property
-ifUp iface = cmdProperty "ifup" [iface]
+-- | A file in the interfaces.d directory.
+interfaceDFile :: Interface -> FilePath
+interfaceDFile iface = "/etc/network/interfaces.d" </> iface
+
+-- | Ensures that files in the the interfaces.d directory are used.
+interfacesDEnabled :: Property NoInfo
+interfacesDEnabled = containsLine interfacesFile "source-directory interfaces.d"
+	`describe` "interfaces.d directory enabled"