{- git-annex assistant pairing network code - - All network traffic is sent over multicast UDP. For reliability, - each message is repeated until acknowledged. This is done using a - thread, that gets stopped before the next message is sent. - - Copyright 2012 Joey Hess - - Licensed under the GNU GPL version 3 or higher. -} module Assistant.Pairing.Network where import Assistant.Common import Assistant.Pairing import Assistant.DaemonStatus import Utility.ThreadScheduler import Utility.Verifiable import Network.Multicast import Network.Info import Network.Socket import Control.Exception (bracket) import qualified Data.Map as M import Control.Concurrent {- This is an arbitrary port in the dynamic port range, that could - conceivably be used for some other broadcast messages. - If so, hope they ignore the garbage from us; we'll certianly - ignore garbage from them. Wild wild west. -} pairingPort :: PortNumber pairingPort = 55556 {- Goal: Reach all hosts on the same network segment. - Method: Use same address that avahi uses. Other broadcast addresses seem - to not be let through some routers. -} multicastAddress :: SomeAddr -> HostName multicastAddress (IPv4Addr _) = "224.0.0.251" multicastAddress (IPv6Addr _) = "ff02::fb" {- Multicasts a message repeatedly on all interfaces, with a 2 second - delay between each transmission. The message is repeated forever - unless a number of repeats is specified. - - The remoteHostAddress is set to the interface's IP address. - - Note that new sockets are opened each time. This is hardly efficient, - but it allows new network interfaces to be used as they come up. - On the other hand, the expensive DNS lookups are cached. -} multicastPairMsg :: Maybe Int -> Secret -> PairData -> PairStage -> IO () multicastPairMsg repeats secret pairdata stage = go M.empty repeats where go _ (Just 0) = noop go cache n = do addrs <- activeNetworkAddresses let cache' = updatecache cache addrs mapM_ (sendinterface cache') addrs threadDelaySeconds (Seconds 2) go cache' $ pred <$> n {- The multicast library currently chokes on ipv6 addresses. -} sendinterface _ (IPv6Addr _) = noop sendinterface cache i = void $ catchMaybeIO $ withSocketsDo $ bracket setup cleanup use where setup = multicastSender (multicastAddress i) pairingPort cleanup (sock, _) = sClose sock -- FIXME does not work use (sock, addr) = do setInterface sock (showAddr i) maybe noop (\s -> void $ sendTo sock s addr) (M.lookup i cache) updatecache cache [] = cache updatecache cache (i:is) | M.member i cache = updatecache cache is | otherwise = updatecache (M.insert i (show $ mkmsg i) cache) is mkmsg addr = PairMsg $ mkVerifiable (stage, pairdata, addr) secret startSending :: PairingInProgress -> PairStage -> (PairStage -> IO ()) -> Assistant () startSending pip stage sender = do a <- asIO start void $ liftIO $ forkIO a where start = do tid <- liftIO myThreadId let pip' = pip { inProgressPairStage = stage, inProgressThreadId = Just tid } oldpip <- modifyDaemonStatus $ \s -> (s { pairingInProgress = Just pip' }, pairingInProgress s) maybe noop stopold oldpip liftIO $ sender stage stopold = maybe noop (liftIO . killThread) . inProgressThreadId stopSending :: PairingInProgress -> Assistant () stopSending pip = do maybe noop (liftIO . killThread) $ inProgressThreadId pip modifyDaemonStatus_ $ \s -> s { pairingInProgress = Nothing } class ToSomeAddr a where toSomeAddr :: a -> SomeAddr instance ToSomeAddr IPv4 where toSomeAddr (IPv4 a) = IPv4Addr a instance ToSomeAddr IPv6 where toSomeAddr (IPv6 o1 o2 o3 o4) = IPv6Addr (o1, o2, o3, o4) showAddr :: SomeAddr -> HostName showAddr (IPv4Addr a) = show $ IPv4 a showAddr (IPv6Addr (o1, o2, o3, o4)) = show $ IPv6 o1 o2 o3 o4 activeNetworkAddresses :: IO [SomeAddr] activeNetworkAddresses = filter (not . all (`elem` "0.:") . showAddr) . concatMap (\ni -> [toSomeAddr $ ipv4 ni, toSomeAddr $ ipv6 ni]) <$> getNetworkInterfaces {- A human-visible description of the repository being paired with. - Note that the repository's description is not shown to the user, because - it could be something like "my repo", which is confusing when pairing - with someone else's repo. However, this has the same format as the - default decription of a repo. -} pairRepo :: PairMsg -> String pairRepo msg = concat [ remoteUserName d , "@" , fromMaybe (showAddr $ pairMsgAddr msg) (remoteHostName d) , ":" , remoteDirectory d ] where d = pairMsgData msg