module Network.Wai.Handler.WebSockets
( websocketsApp
, websocketsOr
, isWebSocketsReq
, getRequestHead
, runWebSockets
) where
import Data.ByteString (ByteString)
import qualified Data.ByteString.Char8 as BC
import qualified Data.CaseInsensitive as CI
import Data.Conduit
import Data.IORef (newIORef, readIORef, writeIORef)
import Network.HTTP.Types (status500)
import qualified Network.Wai as Wai
import qualified Network.WebSockets as WS
import qualified Network.WebSockets.Connection as WS
import System.IO.Streams (InputStream, OutputStream)
import qualified System.IO.Streams as Streams
isWebSocketsReq :: Wai.Request -> Bool
isWebSocketsReq req =
fmap CI.mk (lookup "upgrade" $ Wai.requestHeaders req) == Just "websocket"
websocketsOr :: WS.ConnectionOptions
-> WS.ServerApp
-> Wai.Application
-> Wai.Application
websocketsOr opts app backup req =
case websocketsApp opts app req of
Nothing -> backup req
Just res -> return res
websocketsApp :: WS.ConnectionOptions
-> WS.ServerApp
-> Wai.Request
-> Maybe Wai.Response
websocketsApp opts app req
| isWebSocketsReq req =
Just $ flip Wai.responseRaw backup $ \src sink ->
runWebSockets opts req' app src sink
| otherwise = Nothing
where
req' = getRequestHead req
backup = Wai.responseLBS status500 [("Content-Type", "text/plain")]
"The web application attempted to send a WebSockets response, but WebSockets are not supported by your WAI handler."
getRequestHead :: Wai.Request -> WS.RequestHead
getRequestHead req = WS.RequestHead
(Wai.rawPathInfo req `BC.append` Wai.rawQueryString req)
(Wai.requestHeaders req)
(Wai.isSecure req)
runWebSockets :: WS.ConnectionOptions
-> WS.RequestHead
-> (WS.PendingConnection -> IO a)
-> Source IO ByteString
-> Sink ByteString IO ()
-> IO a
runWebSockets opts req app src sink = do
is <- srcToInput src
os <- sinkToOutput sink >>= Streams.builderStream
let pc = WS.PendingConnection
{ WS.pendingOptions = opts
, WS.pendingRequest = req
, WS.pendingOnAccept = \_ -> return ()
, WS.pendingIn = is
, WS.pendingOut = os
}
app pc
srcToInput :: Source IO ByteString -> IO (InputStream ByteString)
srcToInput src0 = do
(rsrc0, ()) <- src0 $$+ return ()
ref <- newIORef rsrc0
Streams.makeInputStream $ do
rsrc <- readIORef ref
(rsrc', mbs) <- rsrc $$++ await
writeIORef ref rsrc'
return mbs
sinkToOutput :: Sink ByteString IO () -> IO (OutputStream ByteString)
sinkToOutput sink =
Streams.makeOutputStream output
where
output Nothing = return ()
output (Just bs) = yield bs $$ sink