module Network.HTTP.ReverseProxy
(
ProxyDest (..)
, rawProxyTo
, waiProxyTo
, defaultOnExc
, waiToRaw
) where
import ClassyPrelude.Conduit
import qualified Network.Wai as WAI
import qualified Network.HTTP.Conduit as HC
import Control.Exception.Lifted (try, finally)
import Blaze.ByteString.Builder (fromByteString)
import Data.Word8 (isSpace, _colon, toLower, _cr)
import qualified Data.ByteString.Char8 as S8
import qualified Network.HTTP.Types as HT
import qualified Data.CaseInsensitive as CI
import qualified Data.Text.Encoding as TE
import qualified Data.Text.Lazy.Encoding as TLE
import qualified Data.Conduit.Network as DCN
import Control.Concurrent.MVar.Lifted (newEmptyMVar, putMVar, takeMVar)
import Control.Concurrent.Lifted (fork, killThread)
import Control.Monad.Trans.Control (MonadBaseControl)
import Network.Wai.Handler.Warp (defaultSettings, Connection (..), parseRequest, sendResponse, dummyCleaner)
import Data.Conduit.Binary (sourceFileRange)
import qualified Data.IORef as I
import Network.Socket (PortNumber (PortNum), SockAddr (SockAddrInet))
data ProxyDest = ProxyDest
{ pdHost :: !ByteString
, pdPort :: !Int
}
rawProxyTo :: (MonadBaseControl IO m, MonadIO m)
=> (HT.RequestHeaders -> m (Either (DCN.Application m) ProxyDest))
-> DCN.Application m
rawProxyTo getDest appdata = do
(rsrc, headers) <- fromClient $$+ getHeaders
edest <- getDest headers
case edest of
Left app -> do
(fromClient', _) <- unwrapResumable rsrc
app appdata { DCN.appSource = fromClient' }
Right (ProxyDest host port) -> DCN.runTCPClient (DCN.clientSettings port host) (withServer rsrc)
where
fromClient = DCN.appSource appdata
toClient = DCN.appSink appdata
withServer rsrc appdataServer = do
x <- newEmptyMVar
tid1 <- fork $ (rsrc $$+- toServer) `finally` putMVar x True
tid2 <- fork $ (fromServer $$ toClient) `finally` putMVar x False
y <- takeMVar x
killThread $ if y then tid2 else tid1
where
fromServer = DCN.appSource appdataServer
toServer = DCN.appSink appdataServer
defaultOnExc :: SomeException -> WAI.Application
defaultOnExc exc _ = return $ WAI.responseLBS
HT.status502
[("content-type", "text/plain")]
("Error connecting to gateway:\n\n" ++ TLE.encodeUtf8 (show exc))
waiProxyTo :: (WAI.Request -> ResourceT IO (Either WAI.Response ProxyDest))
-> (SomeException -> WAI.Application)
-> HC.Manager
-> WAI.Application
waiProxyTo getDest onError manager req = do
edest <- getDest req
case edest of
Left response -> return response
Right (ProxyDest host port) -> do
let req' = HC.def
{ HC.method = WAI.requestMethod req
, HC.host = host
, HC.port = port
, HC.path = WAI.rawPathInfo req
, HC.queryString = WAI.rawQueryString req
, HC.requestHeaders = filter (\(key, _) -> not $ key `member` strippedHeaders) $ WAI.requestHeaders req
, HC.requestBody = HC.RequestBodySourceChunked $ mapOutput fromByteString $ WAI.requestBody req
, HC.redirectCount = 0
, HC.checkStatus = \_ _ -> Nothing
, HC.responseTimeout = Nothing
}
ex <- try $ HC.http req' manager
case ex of
Left e -> onError e req
Right res -> do
(src, _) <- unwrapResumable $ HC.responseBody res
return $ WAI.ResponseSource
(HC.responseStatus res)
(filter (\(key, _) -> not $ key `member` strippedHeaders) $ HC.responseHeaders res)
(mapOutput (Chunk . fromByteString) src)
where
strippedHeaders = asSet $ fromList ["content-length", "transfer-encoding", "accept-encoding", "content-encoding"]
asSet :: Set a -> Set a
asSet = id
getHeaders :: Monad m => Sink ByteString m HT.RequestHeaders
getHeaders =
toHeaders <$> go id
where
go front =
await >>= maybe close push
where
close = leftover bs >> return bs
where
bs = front empty
push bs'
| "\r\n\r\n" `S8.isInfixOf` bs
|| "\n\n" `S8.isInfixOf` bs
|| length bs > 1000 = leftover bs >> return bs
| otherwise = go $ append bs
where
bs = front bs'
toHeaders = map toHeader . takeWhile (not . null) . drop 1 . S8.lines
toHeader bs =
(CI.mk key, val)
where
(key, bs') = break (== _colon) bs
val = takeWhile (/= _cr) $ dropWhile isSpace $ drop 1 bs'
waiToRaw :: WAI.Application -> DCN.Application IO
waiToRaw app appdata0 =
loop $ transPipe lift fromClient0
where
fromClient0 = DCN.appSource appdata0
toClient = DCN.appSink appdata0
loop fromClient = do
(fromClient', keepAlive) <- runResourceT $ do
(req, fromClient') <- parseRequest conn 0 dummyAddr fromClient
res <- app req
keepAlive <- sendResponse dummyCleaner req conn res
(fromClient'', _) <- liftIO fromClient' >>= unwrapResumable
return (fromClient'', keepAlive)
if keepAlive
then loop fromClient'
else return ()
dummyAddr = SockAddrInet (PortNum 0) 0
conn = Connection
{ connSendMany = \bss -> mapM_ yield bss $$ toClient
, connSendAll = \bs -> yield bs $$ toClient
, connSendFile = \fp offset len _th headers _cleaner ->
let src1 = mapM_ yield headers
src2 = sourceFileRange fp (Just offset) (Just len)
in runResourceT
$ (src1 >> src2)
$$ transPipe lift toClient
, connClose = return ()
, connRecv = error "connRecv should not be used"
}