hook up SRV lookups for XMPP

Assistant/Threads/PushNotifier.hs

@@ -16,15 +16,17 @@ import Assistant.DaemonStatus
 import Assistant.Pushes
 import Assistant.Sync
 import qualified Remote
+import Utility.FileMode
+import Utility.SRV
 
 import Network.Protocol.XMPP
 import Network
 import Control.Concurrent
 import qualified Data.Text as T
 import qualified Data.Set as S
-import Utility.FileMode
 import qualified Git.Branch
 import Data.XML.Types
+import Control.Exception as E
 
 thisThread :: ThreadName
 thisThread = "PushNotifier"
@@ -33,27 +35,16 @@ pushNotifierThread :: ThreadState -> DaemonStatusHandle -> PushNotifier -> Named
 pushNotifierThread st dstatus pushnotifier = NamedThread thisThread $ do
 	v <- runThreadState st $ getXMPPCreds
 	case v of
-		Nothing -> nocreds
-		Just c -> case parseJID (xmppJID c) of
-			Nothing -> nocreds
-			Just jid -> void $ client c jid
-	where
-		nocreds = do
-			error "no creds" -- TODO alert
-			return () -- exit thread
-
-		client c jid = runClient server jid (xmppUsername c) (xmppPassword c) $ do
-			void $ bindJID jid
+		Nothing -> do
+			return () -- no creds? exit thread
+		Just c -> void $ connectXMPP c $ \jid -> do
+			fulljid <- bindJID jid
+			liftIO $ debug thisThread ["XMPP connected", show fulljid]
 			s <- getSession
 			_ <- liftIO $ forkOS $ void $ runXMPP s $
 				receivenotifications
 			sendnotifications
-			where
-				server = Server
-					(JID Nothing (jidDomain jid) Nothing)
-					(xmppHostname c)
-					(PortNumber $ fromIntegral $ xmppPort c)
-
+	where
 		sendnotifications = forever $ do
 			us <- liftIO $ waitPush pushnotifier
 			let payload = [extendedAway, encodePushNotification us]
@@ -78,12 +69,43 @@ data XMPPCreds = XMPPCreds
 	, xmppPassword :: T.Text
 	, xmppHostname :: HostName
 	, xmppPort :: Int
-	{- Something like username@hostname, but not necessarily the same
-	 - username or hostname used to connect to the server. -}
 	, xmppJID :: T.Text
 	}
 	deriving (Read, Show)
 
+{- Note that this must be run in a bound thread; gnuTLS requires it. -}
+connectXMPP :: XMPPCreds -> (JID -> XMPP a) -> IO (Either SomeException ())
+connectXMPP c a = case parseJID (xmppJID c) of
+	Nothing -> error "bad JID"
+	Just jid -> connectXMPP' jid c a
+
+{- Do a SRV lookup, but if it fails, fall back to the cached xmppHostname. -}
+connectXMPP' :: JID -> XMPPCreds -> (JID -> XMPP a) -> IO (Either SomeException ())
+connectXMPP' jid c a = go =<< lookupSRV srvrecord
+	where
+		srvrecord = "_xmpp-client._tcp." ++ (T.unpack $ strDomain $ jidDomain jid)
+		serverjid = JID Nothing (jidDomain jid) Nothing
+
+		go [] = run (xmppHostname c)
+				(PortNumber $ fromIntegral $ xmppPort c)
+				(a jid)
+		go ((h,p):rest) = do
+			{- Try each SRV record in turn, until one connects,
+			 - at which point the MVar will be full. -}
+			mv <- newEmptyMVar
+			r <- run h p $ do
+				liftIO $ putMVar mv ()
+				a jid
+			ifM (isEmptyMVar mv) (go rest, return r)
+
+		run h p a' = do
+			liftIO $ debug thisThread ["XMPP trying", h]
+			E.try (runClientError (Server serverjid h p) jid (xmppUsername c) (xmppPassword c) (void a')) :: IO (Either SomeException ())
+
+{- XMPP runClient, that throws errors rather than returning an Either -}
+runClientError :: Server -> JID -> T.Text -> T.Text -> XMPP a -> IO a
+runClientError s j u p x = either (error . show) return =<< runClient s j u p x
+
 getXMPPCreds :: Annex (Maybe XMPPCreds)
 getXMPPCreds = do
 	f <- xmppCredsFile