git-annex/Annex/Ssh.hs
Joey Hess 0ae08947ac
Run ssh with ServerAliveInterval 60
So that stalled transfers will be noticed within about 3 minutes,
even if TCPKeepAlive is disabled or doesn't work.

Rather than setting with -o, use -F with another config file,
so that any settings in ~/.ssh/config or /etc/ssh/ssh_config overrides this.
2016-10-26 16:41:34 -04:00

341 lines
11 KiB
Haskell

{- git-annex ssh interface, with connection caching
-
- Copyright 2012-2015 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Annex.Ssh (
sshOptions,
sshCacheDir,
sshReadPort,
forceSshCleanup,
sshOptionsEnv,
sshOptionsTo,
inRepoWithSshOptionsTo,
runSshOptions,
sshAskPassEnv,
runSshAskPass
) where
import qualified Data.Map as M
import Data.Hash.MD5
import System.Exit
import Annex.Common
import Annex.LockFile
import qualified Build.SysConfig as SysConfig
import qualified Annex
import qualified Git
import qualified Git.Url
import Config
import Annex.Path
import Utility.Env
import Utility.Tmp
import Types.CleanupActions
import Git.Env
#ifndef mingw32_HOST_OS
import Annex.Perms
import Annex.LockPool
#endif
{- Generates parameters to ssh to a given host (or user@host) on a given
- port. This includes connection caching parameters, and any ssh-options. -}
sshOptions :: (String, Maybe Integer) -> RemoteGitConfig -> [CommandParam] -> Annex [CommandParam]
sshOptions (host, port) gc opts = go =<< sshCachingInfo (host, port)
where
go (Nothing, params) = ret params
go (Just socketfile, params) = do
prepSocket socketfile
ret params
ret ps = do
overideconfigfile <- fromRepo gitAnnexSshConfig
-- We assume that the file content does not change.
-- If it did, a more expensive test would be needed.
liftIO $ unlessM (doesFileExist overideconfigfile) $
viaTmp writeFile overideconfigfile $ unlines
-- ssh expands "~"
[ "Include ~/.ssh/config"
-- ssh will silently skip the file
-- if it does not exist
, "Include /etc/ssh/ssh_config"
-- Everything below this point is only
-- used if there's no setting for it in
-- the above files.
--
-- Make sure that ssh detects stalled
-- connections.
, "ServerAliveInterval 60"
]
return $ concat
[ ps
, [Param "-F", File overideconfigfile]
, map Param (remoteAnnexSshOptions gc)
, opts
, portParams port
, [Param "-T"]
]
{- Returns a filename to use for a ssh connection caching socket, and
- parameters to enable ssh connection caching. -}
sshCachingInfo :: (String, Maybe Integer) -> Annex (Maybe FilePath, [CommandParam])
sshCachingInfo (host, port) = go =<< sshCacheDir
where
go Nothing = return (Nothing, [])
go (Just dir) = do
r <- liftIO $ bestSocketPath $ dir </> hostport2socket host port
return $ case r of
Nothing -> (Nothing, [])
Just socketfile -> (Just socketfile, sshConnectionCachingParams socketfile)
{- Given an absolute path to use for a socket file,
- returns whichever is shorter of that or the relative path to the same
- file.
-
- If no path can be constructed that is a valid socket, returns Nothing. -}
bestSocketPath :: FilePath -> IO (Maybe FilePath)
bestSocketPath abssocketfile = do
relsocketfile <- liftIO $ relPathCwdToFile abssocketfile
let socketfile = if length abssocketfile <= length relsocketfile
then abssocketfile
else relsocketfile
return $ if valid_unix_socket_path (socketfile ++ sshgarbage)
then Just socketfile
else Nothing
where
-- ssh appends a 16 char extension to the socket when setting it
-- up, which needs to be taken into account when checking
-- that a valid socket was constructed.
sshgarbage = replicate (1+16) 'X'
sshConnectionCachingParams :: FilePath -> [CommandParam]
sshConnectionCachingParams socketfile =
[ Param "-S", Param socketfile
, Param "-o", Param "ControlMaster=auto"
, Param "-o", Param "ControlPersist=yes"
]
{- ssh connection caching creates sockets, so will not work on a
- crippled filesystem. A GIT_ANNEX_TMP_DIR can be provided to use
- a different filesystem. -}
sshCacheDir :: Annex (Maybe FilePath)
sshCacheDir
| SysConfig.sshconnectioncaching =
ifM (fromMaybe True . annexSshCaching <$> Annex.getGitConfig)
( ifM crippledFileSystem
( maybe (return Nothing) usetmpdir =<< gettmpdir
, Just <$> fromRepo gitAnnexSshDir
)
, return Nothing
)
| otherwise = return Nothing
where
gettmpdir = liftIO $ getEnv "GIT_ANNEX_TMP_DIR"
usetmpdir tmpdir = liftIO $ catchMaybeIO $ do
let socktmp = tmpdir </> "ssh"
createDirectoryIfMissing True socktmp
return socktmp
portParams :: Maybe Integer -> [CommandParam]
portParams Nothing = []
portParams (Just port) = [Param "-p", Param $ show port]
{- Prepare to use a socket file. Locks a lock file to prevent
- other git-annex processes from stopping the ssh on this socket. -}
prepSocket :: FilePath -> Annex ()
prepSocket socketfile = do
-- If the lock pool is empty, this is the first ssh of this
-- run. There could be stale ssh connections hanging around
-- from a previous git-annex run that was interrupted.
whenM (not . any isLock . M.keys <$> getLockCache)
sshCleanup
-- Cleanup at end of this run.
Annex.addCleanup SshCachingCleanup sshCleanup
liftIO $ createDirectoryIfMissing True $ parentDir socketfile
lockFileCached $ socket2lock socketfile
{- Find ssh socket files.
-
- The check that the lock file exists makes only socket files
- that were set up by prepSocket be found. On some NFS systems,
- a deleted socket file may linger for a while under another filename;
- and this check makes such files be skipped since the corresponding lock
- file won't exist.
-}
enumSocketFiles :: Annex [FilePath]
enumSocketFiles = liftIO . go =<< sshCacheDir
where
go Nothing = return []
go (Just dir) = filterM (doesFileExist . socket2lock)
=<< filter (not . isLock)
<$> catchDefaultIO [] (dirContents dir)
{- Stop any unused ssh connection caching processes. -}
sshCleanup :: Annex ()
sshCleanup = mapM_ cleanup =<< enumSocketFiles
where
cleanup socketfile = do
#ifndef mingw32_HOST_OS
-- Drop any shared lock we have, and take an
-- exclusive lock, without blocking. If the lock
-- succeeds, nothing is using this ssh, and it can
-- be stopped.
--
-- After ssh is stopped cannot remove the lock file;
-- other processes may be waiting on our exclusive
-- lock to use it.
let lockfile = socket2lock socketfile
unlockFile lockfile
mode <- annexFileMode
v <- noUmask mode $ tryLockExclusive (Just mode) lockfile
case v of
Nothing -> noop
Just lck -> do
forceStopSsh socketfile
liftIO $ dropLock lck
#else
forceStopSsh socketfile
#endif
{- Stop all ssh connection caching processes, even when they're in use. -}
forceSshCleanup :: Annex ()
forceSshCleanup = mapM_ forceStopSsh =<< enumSocketFiles
forceStopSsh :: FilePath -> Annex ()
forceStopSsh socketfile = do
let (dir, base) = splitFileName socketfile
let params = sshConnectionCachingParams base
-- "ssh -O stop" is noisy on stderr even with -q
void $ liftIO $ catchMaybeIO $
withQuietOutput createProcessSuccess $
(proc "ssh" $ toCommand $
[ Param "-O", Param "stop" ] ++
params ++ [Param "localhost"])
{ cwd = Just dir }
liftIO $ nukeFile socketfile
{- This needs to be as short as possible, due to limitations on the length
- of the path to a socket file. At the same time, it needs to be unique
- for each host.
-}
hostport2socket :: String -> Maybe Integer -> FilePath
hostport2socket host Nothing = hostport2socket' host
hostport2socket host (Just port) = hostport2socket' $ host ++ "!" ++ show port
hostport2socket' :: String -> FilePath
hostport2socket' s
| length s > lengthofmd5s = md5s (Str s)
| otherwise = s
where
lengthofmd5s = 32
socket2lock :: FilePath -> FilePath
socket2lock socket = socket ++ lockExt
isLock :: FilePath -> Bool
isLock f = lockExt `isSuffixOf` f
lockExt :: String
lockExt = ".lock"
{- This is the size of the sun_path component of sockaddr_un, which
- is the limit to the total length of the filename of a unix socket.
-
- On Linux, this is 108. On OSX, 104. TODO: Probe
-}
sizeof_sockaddr_un_sun_path :: Int
sizeof_sockaddr_un_sun_path = 100
{- Note that this looks at the true length of the path in bytes, as it will
- appear on disk. -}
valid_unix_socket_path :: FilePath -> Bool
valid_unix_socket_path f = length (decodeW8 f) < sizeof_sockaddr_un_sun_path
{- Parses the SSH port, and returns the other OpenSSH options. If
- several ports are found, the last one takes precedence. -}
sshReadPort :: [String] -> (Maybe Integer, [String])
sshReadPort params = (port, reverse args)
where
(port,args) = aux (Nothing, []) params
aux (p,ps) [] = (p,ps)
aux (_,ps) ("-p":p:rest) = aux (readPort p, ps) rest
aux (p,ps) (q:rest) | "-p" `isPrefixOf` q = aux (readPort $ drop 2 q, ps) rest
| otherwise = aux (p,q:ps) rest
readPort p = fmap fst $ listToMaybe $ reads p
{- When this env var is set, git-annex runs ssh with the specified
- options. (The options are separated by newlines.)
-
- This is a workaround for GIT_SSH not being able to contain
- additional parameters to pass to ssh. -}
sshOptionsEnv :: String
sshOptionsEnv = "GIT_ANNEX_SSHOPTION"
toSshOptionsEnv :: [CommandParam] -> String
toSshOptionsEnv = unlines . toCommand
fromSshOptionsEnv :: String -> [CommandParam]
fromSshOptionsEnv = map Param . lines
{- Enables ssh caching for git push/pull to a particular
- remote git repo. (Can safely be used on non-ssh remotes.)
-
- Also propigates any configured ssh-options.
-
- Like inRepo, the action is run with the local git repo.
- But here it's a modified version, with gitEnv to set GIT_SSH=git-annex,
- and sshOptionsEnv set so that git-annex will know what socket
- file to use. -}
inRepoWithSshOptionsTo :: Git.Repo -> RemoteGitConfig -> (Git.Repo -> IO a) -> Annex a
inRepoWithSshOptionsTo remote gc a =
liftIO . a =<< sshOptionsTo remote gc =<< gitRepo
{- To make any git commands be run with ssh caching enabled,
- and configured ssh-options alters the local Git.Repo's gitEnv
- to set GIT_SSH=git-annex, and set sshOptionsEnv when running git
- commands. -}
sshOptionsTo :: Git.Repo -> RemoteGitConfig -> Git.Repo -> Annex Git.Repo
sshOptionsTo remote gc localr
| not (Git.repoIsUrl remote) || Git.repoIsHttp remote = unchanged
| otherwise = case Git.Url.hostuser remote of
Nothing -> unchanged
Just host -> do
(msockfile, _) <- sshCachingInfo (host, Git.Url.port remote)
case msockfile of
Nothing -> use []
Just sockfile -> do
prepSocket sockfile
use (sshConnectionCachingParams sockfile)
where
unchanged = return localr
use opts = do
let sshopts = concat
[ opts
, map Param (remoteAnnexSshOptions gc)
]
if null sshopts
then unchanged
else do
command <- liftIO programPath
liftIO $ do
localr' <- addGitEnv localr sshOptionsEnv
(toSshOptionsEnv sshopts)
addGitEnv localr' "GIT_SSH" command
runSshOptions :: [String] -> String -> IO ()
runSshOptions args s = do
let args' = toCommand (fromSshOptionsEnv s) ++ args
let p = proc "ssh" args'
exitWith =<< waitForProcess . processHandle =<< createProcess p
{- When this env var is set, git-annex is being used as a ssh-askpass
- program, and should read the password from the specified location,
- and output it for ssh to read. -}
sshAskPassEnv :: String
sshAskPassEnv = "GIT_ANNEX_SSHASKPASS"
runSshAskPass :: FilePath -> IO ()
runSshAskPass passfile = putStrLn =<< readFile passfile