Discovery service

1 files changed, 223 insertions, 0 deletions

diff --git a/src/Discovery.hs b/src/Discovery.hs
new file mode 100644
index 0000000..aedfda4
--- /dev/null
+++ b/src/Discovery.hs
@@ -0,0 +1,223 @@
+module Discovery (
+    DiscoveryService(..),
+    DiscoveryConnection(..)
+) where
+
+import Control.Concurrent
+import Control.Monad.Except
+import Control.Monad.Reader
+
+import Data.Map.Strict (Map)
+import qualified Data.Map.Strict as M
+import Data.Maybe
+import Data.Text (Text)
+import qualified Data.Text as T
+
+import Network.Socket
+
+import ICE
+import Identity
+import Network
+import Service
+import Storage
+
+
+keepaliveSeconds :: Int
+keepaliveSeconds = 20
+
+
+data DiscoveryService = DiscoverySelf Text Int
+                      | DiscoveryAcknowledged Text
+                      | DiscoverySearch Ref
+                      | DiscoveryResult Ref (Maybe Text)
+                      | DiscoveryConnectionRequest DiscoveryConnection
+                      | DiscoveryConnectionResponse DiscoveryConnection
+
+data DiscoveryConnection = DiscoveryConnection
+    { dconnSource :: Ref
+    , dconnTarget :: Ref
+    , dconnAddress :: Maybe Text
+    , dconnIceSession :: Maybe IceRemoteInfo
+    }
+
+emptyConnection :: Ref -> Ref -> DiscoveryConnection
+emptyConnection source target = DiscoveryConnection source target Nothing Nothing
+
+instance Storable DiscoveryService where
+    store' x = storeRec $ do
+        case x of
+            DiscoverySelf addr priority -> do
+                storeText "self" addr
+                storeInt "priority" priority
+            DiscoveryAcknowledged addr -> do
+                storeText "ack" addr
+            DiscoverySearch ref -> storeRawRef "search" ref
+            DiscoveryResult ref addr -> do
+                storeRawRef "result" ref
+                storeMbText "address" addr
+            DiscoveryConnectionRequest conn -> storeConnection "request" conn
+            DiscoveryConnectionResponse conn -> storeConnection "response" conn
+
+        where storeConnection ctype conn = do
+                  storeText "connection" $ ctype
+                  storeRawRef "source" $ dconnSource conn
+                  storeRawRef "target" $ dconnTarget conn
+                  storeMbText "address" $ dconnAddress conn
+                  storeMbRef "ice-session" $ dconnIceSession conn
+
+    load' = loadRec $ msum
+            [ DiscoverySelf
+                <$> loadText "self"
+                <*> loadInt "priority"
+            , DiscoveryAcknowledged
+                <$> loadText "ack"
+            , DiscoverySearch <$> loadRawRef "search"
+            , DiscoveryResult
+                <$> loadRawRef "result"
+                <*> loadMbText "address"
+            , loadConnection "request" DiscoveryConnectionRequest
+            , loadConnection "response" DiscoveryConnectionResponse
+            ]
+        where loadConnection ctype ctor = do
+                  ctype' <- loadText "connection"
+                  guard $ ctype == ctype'
+                  return . ctor =<< DiscoveryConnection
+                      <$> loadRawRef "source"
+                      <*> loadRawRef "target"
+                      <*> loadMbText "address"
+                      <*> loadMbRef "ice-session"
+
+data DiscoveryPeer = DiscoveryPeer
+    { dpPriority :: Int
+    , dpPeer :: Maybe Peer
+    , dpAddress :: Maybe Text
+    , dpIceSession :: Maybe IceSession
+    }
+
+instance Service DiscoveryService where
+    serviceID _ = mkServiceID "dd59c89c-69cc-4703-b75b-4ddcd4b3c23b"
+
+    type ServiceGlobalState DiscoveryService = Map RefDigest DiscoveryPeer
+    emptyServiceGlobalState _ = M.empty
+
+    serviceHandler msg = case fromStored msg of
+        DiscoverySelf addr priority -> do
+            pid <- asks svcPeerIdentity
+            peer <- asks svcPeer
+            let insertHelper new old | dpPriority new > dpPriority old = new
+                                     | otherwise                       = old
+            mbaddr <- case words (T.unpack addr) of
+                [ipaddr, port] | DatagramAddress _ paddr <- peerAddress peer -> do
+                    saddr <- liftIO $ head <$> getAddrInfo (Just $ defaultHints { addrSocketType = Datagram }) (Just ipaddr) (Just port)
+                    return $ if paddr == addrAddress saddr
+                                then Just addr
+                                else Nothing
+                _ -> return Nothing
+            forM_ (idDataF =<< unfoldOwners pid) $ \s ->
+                svcModifyGlobal $ M.insertWith insertHelper (refDigest $ storedRef s) $
+                    DiscoveryPeer priority (Just peer) mbaddr Nothing
+            replyPacket $ DiscoveryAcknowledged $ fromMaybe (T.pack "ICE") mbaddr
+
+        DiscoveryAcknowledged addr -> do
+            when (addr == T.pack "ICE") $ do
+                -- keep-alive packet from behind NAT
+                self <- svcSelf
+                peer <- asks svcPeer
+                liftIO $ void $ forkIO $ do
+                    threadDelay (keepaliveSeconds * 1000 * 1000)
+                    res <- runExceptT $ sendToPeer self peer $ DiscoverySelf addr 0
+                    case res of
+                        Right _ -> return ()
+                        Left err -> putStrLn $ "Discovery: failed to send keep-alive: " ++ err
+
+        DiscoverySearch ref -> do
+            addr <- M.lookup (refDigest ref) <$> svcGetGlobal
+            replyPacket $ DiscoveryResult ref $ fromMaybe (T.pack "ICE") . dpAddress <$> addr
+
+        DiscoveryResult ref Nothing -> do
+            svcPrint $ "Discovery: " ++ show (refDigest ref) ++ " not found"
+
+        DiscoveryResult ref (Just addr) -> do
+            -- TODO: check if we really requested that
+            server <- asks svcServer
+            if addr == T.pack "ICE"
+               then do
+                    self <- svcSelf
+                    peer <- asks svcPeer
+                    ice <- liftIO $ iceCreate PjIceSessRoleControlling $ \ice -> do
+                        rinfo <- iceRemoteInfo ice
+                        res <- runExceptT $ sendToPeer self peer $
+                            DiscoveryConnectionRequest (emptyConnection (storedRef $ idData self) ref) { dconnIceSession = Just rinfo }
+                        case res of
+                            Right _ -> return ()
+                            Left err -> putStrLn $ "Discovery: failed to send connection request: " ++ err
+
+                    svcModifyGlobal $ M.insert (refDigest ref) $
+                        DiscoveryPeer 0 Nothing Nothing (Just ice)
+               else do
+                    case words (T.unpack addr) of
+                        [ipaddr, port] -> do
+                            saddr <- liftIO $ head <$>
+                                getAddrInfo (Just $ defaultHints { addrSocketType = Datagram }) (Just ipaddr) (Just port)
+                            peer <- liftIO $ serverPeer server (addrAddress saddr)
+                            svcModifyGlobal $ M.insert (refDigest ref) $
+                                DiscoveryPeer 0 (Just peer) Nothing Nothing
+
+                        _ -> svcPrint $ "Discovery: invalid address in result: " ++ T.unpack addr
+
+        DiscoveryConnectionRequest conn -> do
+            self <- svcSelf
+            let rconn = emptyConnection (dconnSource conn) (dconnTarget conn)
+            if refDigest (dconnTarget conn) `elem` (map (refDigest . storedRef) $ idDataF =<< unfoldOwners self)
+               then do
+                    -- request for us, create ICE sesssion
+                    server <- asks svcServer
+                    peer <- asks svcPeer
+                    liftIO $ void $ iceCreate PjIceSessRoleControlled $ \ice -> do
+                        rinfo <- iceRemoteInfo ice
+                        res <- runExceptT $ sendToPeer self peer $ DiscoveryConnectionResponse rconn { dconnIceSession = Just rinfo }
+                        case res of
+                            Right _ -> do
+                                case dconnIceSession conn of
+                                    Just prinfo -> iceConnect ice prinfo $ void $ serverPeerIce server ice
+                                    Nothing -> putStrLn $ "Discovery: connection request without ICE remote info"
+                            Left err -> putStrLn $ "Discovery: failed to send connection response: " ++ err
+
+               else do
+                    -- request to some of our peers, relay
+                    mbdp <- M.lookup (refDigest $ dconnTarget conn) <$> svcGetGlobal
+                    case mbdp of
+                        Nothing -> replyPacket $ DiscoveryConnectionResponse rconn
+                        Just dp | Just addr <- dpAddress dp -> do
+                                    replyPacket $ DiscoveryConnectionResponse rconn { dconnAddress = Just addr }
+                                | Just dpeer <- dpPeer dp -> do
+                                    sendToPeer self dpeer $ DiscoveryConnectionRequest conn
+                                | otherwise -> svcPrint $ "Discovery: failed to relay connection request"
+
+        DiscoveryConnectionResponse conn -> do
+            self <- svcSelf
+            dpeers <- svcGetGlobal
+            if refDigest (dconnSource conn) `elem` (map (refDigest . storedRef) $ idDataF =<< unfoldOwners self)
+               then do
+                    -- response to our request, try to connect to the peer
+                    server <- asks svcServer
+                    if  | Just addr <- dconnAddress conn
+                        , [ipaddr, port] <- words (T.unpack addr) -> do
+                            saddr <- liftIO $ head <$>
+                                getAddrInfo (Just $ defaultHints { addrSocketType = Datagram }) (Just ipaddr) (Just port)
+                            peer <- liftIO $ serverPeer server (addrAddress saddr)
+                            svcModifyGlobal $ M.insert (refDigest $ dconnTarget conn) $
+                                DiscoveryPeer 0 (Just peer) Nothing Nothing
+
+                        | Just dp <- M.lookup (refDigest $ dconnTarget conn) dpeers
+                        , Just ice <- dpIceSession dp
+                        , Just rinfo <- dconnIceSession conn -> do
+                            liftIO $ iceConnect ice rinfo $ void $ serverPeerIce server ice
+
+                        | otherwise -> svcPrint $ "Discovery: connection request failed"
+               else do
+                    -- response to relayed request
+                    case M.lookup (refDigest $ dconnSource conn) dpeers of
+                        Just dp | Just dpeer <- dpPeer dp -> do
+                            sendToPeer self dpeer $ DiscoveryConnectionResponse conn
+                        _ -> svcPrint $ "Discovery: failed to relay connection response"