factor out ssh module

1 files changed, 43 insertions, 0 deletions

diff --git a/src/Propellor/Ssh.hs b/src/Propellor/Ssh.hs
new file mode 100644
index 00000000..969517a8
--- /dev/null
+++ b/src/Propellor/Ssh.hs
@@ -0,0 +1,43 @@
+module Propellor.Ssh where
+
+import Propellor
+import Utility.SafeCommand
+import Utility.UserInfo
+
+import System.PosixCompat
+import Data.Time.Clock.POSIX
+
+-- Parameters can be passed to both ssh and scp, to enable a ssh connection
+-- caching socket.
+--
+-- If the socket already exists, check if its mtime is older than 10
+-- minutes, and if so stop that ssh process, in order to not try to
+-- use an old stale connection. (atime would be nicer, but there's
+-- a good chance a laptop uses noatime)
+sshCachingParams :: HostName -> IO [CommandParam]
+sshCachingParams hn = do
+	home <- myHomeDir
+	let cachedir = home </> ".ssh" </> "propellor"
+	createDirectoryIfMissing False cachedir
+	let socketfile = cachedir </> hn ++ ".sock"
+	let ps = 
+		[ Param "-o", Param ("ControlPath=" ++ socketfile)
+		, Params "-o ControlMaster=auto -o ControlPersist=yes"
+		]
+
+	maybe noop (expireold ps socketfile)
+		=<< catchMaybeIO (getFileStatus socketfile)
+	
+	return ps
+		
+  where
+	expireold ps f s = do
+		now <- truncate <$> getPOSIXTime :: IO Integer
+		if modificationTime s > fromIntegral now - tenminutes
+			then touchFile f
+			else do
+				void $ boolSystem "ssh" $
+					[ Params "-O stop" ] ++ ps ++
+					[ Param "localhost" ]
+				nukeFile f
+	tenminutes = 600