139 lines
4.3 KiB
Haskell
139 lines
4.3 KiB
Haskell
{- git-annex ssh interface, with connection caching
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-
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- Copyright 2012 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Annex.Ssh (
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sshParams,
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sshCleanup,
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) where
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import qualified Data.Map as M
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import Common.Annex
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import Annex.LockPool
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import qualified Git.Config
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import Config
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import qualified Build.SysConfig as SysConfig
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import Annex.Perms
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{- Generates parameters to ssh to a given host (or user@host) on a given
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- port, with connection caching. -}
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sshParams :: (String, Maybe Integer) -> [CommandParam] -> Annex [CommandParam]
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sshParams (host, port) opts = go =<< sshInfo (host, port)
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where
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go (Nothing, params) = ret params
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go (Just socketfile, params) = do
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cleanstale
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liftIO $ createDirectoryIfMissing True $ parentDir socketfile
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lockFile $ socket2lock socketfile
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ret params
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ret ps = return $ ps ++ opts ++ portParams port ++ [Param host]
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-- If the lock pool is empty, this is the first ssh of this
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-- run. There could be stale ssh connections hanging around
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-- from a previous git-annex run that was interrupted.
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cleanstale = whenM (not . any isLock . M.keys <$> getPool) $
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sshCleanup
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sshInfo :: (String, Maybe Integer) -> Annex (Maybe FilePath, [CommandParam])
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sshInfo (host, port) = ifM caching
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( do
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dir <- fromRepo gitAnnexSshDir
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let socketfile = dir </> hostport2socket host port
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if valid_unix_socket_path socketfile
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then return (Just socketfile, cacheParams socketfile)
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else do
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socketfile' <- liftIO $ relPathCwdToFile socketfile
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if valid_unix_socket_path socketfile'
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then return (Just socketfile', cacheParams socketfile')
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else return (Nothing, [])
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, return (Nothing, [])
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)
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where
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caching = fromMaybe SysConfig.sshconnectioncaching
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. Git.Config.isTrue
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<$> getConfig (annexConfig "sshcaching") ""
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cacheParams :: FilePath -> [CommandParam]
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cacheParams socketfile =
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[ Param "-S", Param socketfile
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, Params "-o ControlMaster=auto -o ControlPersist=yes"
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]
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portParams :: Maybe Integer -> [CommandParam]
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portParams Nothing = []
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portParams (Just port) = [Param "-p", Param $ show port]
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{- Stop any unused ssh processes. -}
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sshCleanup :: Annex ()
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sshCleanup = do
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dir <- fromRepo gitAnnexSshDir
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sockets <- filter (not . isLock) <$>
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liftIO (catchDefaultIO [] $ dirContents dir)
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forM_ sockets cleanup
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where
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cleanup socketfile = do
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-- Drop any shared lock we have, and take an
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-- exclusive lock, without blocking. If the lock
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-- succeeds, nothing is using this ssh, and it can
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-- be stopped.
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let lockfile = socket2lock socketfile
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unlockFile lockfile
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mode <- annexFileMode
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fd <- liftIO $ noUmask mode $
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openFd lockfile ReadWrite (Just mode) defaultFileFlags
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v <- liftIO $ tryIO $
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setLock fd (WriteLock, AbsoluteSeek, 0, 0)
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case v of
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Left _ -> noop
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Right _ -> stopssh socketfile
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liftIO $ closeFd fd
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stopssh socketfile = do
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let (host, port) = socket2hostport socketfile
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(_, params) <- sshInfo (host, port)
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void $ liftIO $ do
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-- "ssh -O stop" is noisy on stderr even with -q
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let cmd = unwords $ toCommand $
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[ Params "-O stop"
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] ++ params ++ [Param host]
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boolSystem "sh"
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[ Param "-c"
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, Param $ "ssh " ++ cmd ++ " >/dev/null 2>/dev/null"
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]
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-- Cannot remove the lock file; other processes may
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-- be waiting on our exclusive lock to use it.
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hostport2socket :: String -> Maybe Integer -> FilePath
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hostport2socket host Nothing = host
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hostport2socket host (Just port) = host ++ "!" ++ show port
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socket2hostport :: FilePath -> (String, Maybe Integer)
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socket2hostport socket
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| null p = (h, Nothing)
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| otherwise = (h, readish p)
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where
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(h, p) = separate (== '!') $ takeFileName socket
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socket2lock :: FilePath -> FilePath
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socket2lock socket = socket ++ lockExt
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isLock :: FilePath -> Bool
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isLock f = lockExt `isSuffixOf` f
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lockExt :: String
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lockExt = ".lock"
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{- This is the size of the sun_path component of sockaddr_un, which
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- is the limit to the total length of the filename of a unix socket.
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-
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- On Linux, this is 108. On OSX, 104. TODO: Probe
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-}
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sizeof_sockaddr_un_sun_path :: Int
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sizeof_sockaddr_un_sun_path = 100
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{- Note that this looks at the true length of the path in bytes, as it will
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- appear on disk. -}
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valid_unix_socket_path :: FilePath -> Bool
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valid_unix_socket_path f = length (decodeW8 f) < sizeof_sockaddr_un_sun_path
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