module Network.HTTP.ReverseProxy
(
ProxyDest (..)
, rawProxyTo
, waiProxyTo
, defaultOnExc
, waiProxyToSettings
, WaiProxyResponse (..)
, WaiProxySettings
, def
, wpsOnExc
, wpsTimeout
, wpsSetIpHeader
, wpsProcessBody
, wpsUpgradeToRaw
, SetIpHeader (..)
) where
import Data.Conduit
import Data.Streaming.Network (readLens, AppData)
import Data.Functor.Identity (Identity (..))
import Data.Maybe (fromMaybe)
import Control.Monad.Trans.Control (MonadBaseControl)
import Data.Default.Class (def)
import qualified Network.Wai as WAI
import qualified Network.HTTP.Client as HC
import Network.HTTP.Client (BodyReader, brRead)
import Control.Exception (bracket)
import Blaze.ByteString.Builder (fromByteString)
import Data.Word8 (isSpace, _colon, _cr)
import qualified Data.ByteString as S
import qualified Data.ByteString.Char8 as S8
import qualified Network.HTTP.Types as HT
import qualified Data.CaseInsensitive as CI
import qualified Data.Text.Lazy.Encoding as TLE
import qualified Data.Text.Lazy as TL
import qualified Data.Conduit.Network as DCN
import Control.Concurrent.MVar.Lifted (newEmptyMVar, putMVar, takeMVar)
import Control.Concurrent.Lifted (fork, killThread)
import Data.Default.Class (Default (..))
import Network.Wai.Logger (showSockAddr)
import qualified Data.Set as Set
import Data.IORef
import qualified Data.ByteString.Lazy as L
import Control.Concurrent.Async (concurrently)
import Blaze.ByteString.Builder (Builder, toLazyByteString)
import Data.ByteString (ByteString)
import Control.Monad.IO.Class (MonadIO, liftIO)
import Control.Monad (unless, void)
import Data.Monoid (mappend, (<>), mconcat)
import Control.Exception.Lifted (try, SomeException, finally)
import Control.Applicative ((<$>), (<|>))
import Data.Set (Set)
import qualified Data.Conduit.List as CL
data ProxyDest = ProxyDest
{ pdHost :: !ByteString
, pdPort :: !Int
}
rawProxyTo :: (MonadBaseControl IO m, MonadIO m)
=> (HT.RequestHeaders -> m (Either (DCN.AppData -> m ()) ProxyDest))
-> AppData -> m ()
rawProxyTo getDest appdata = do
(rsrc, headers) <- liftIO $ fromClient $$+ getHeaders
edest <- getDest headers
case edest of
Left app -> do
irsrc <- liftIO $ newIORef rsrc
let readData = do
rsrc1 <- readIORef irsrc
(rsrc2, mbs) <- rsrc1 $$++ await
writeIORef irsrc rsrc2
return $ fromMaybe "" mbs
app $ runIdentity (readLens (const (Identity readData)) appdata)
Right (ProxyDest host port) -> liftIO $ 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 _ sendResponse = sendResponse $ WAI.responseLBS
HT.status502
[("content-type", "text/plain")]
("Error connecting to gateway:\n\n" <> TLE.encodeUtf8 (TL.pack $ show exc))
data WaiProxyResponse = WPRResponse WAI.Response
| WPRProxyDest ProxyDest
| WPRModifiedRequest WAI.Request ProxyDest
| WPRApplication WAI.Application
waiProxyTo :: (WAI.Request -> IO WaiProxyResponse)
-> (SomeException -> WAI.Application)
-> HC.Manager
-> WAI.Application
waiProxyTo getDest onError = waiProxyToSettings getDest def { wpsOnExc = onError }
data WaiProxySettings = WaiProxySettings
{ wpsOnExc :: SomeException -> WAI.Application
, wpsTimeout :: Maybe Int
, wpsSetIpHeader :: SetIpHeader
, wpsProcessBody :: HC.Response () -> Maybe (Conduit ByteString IO (Flush Builder))
, wpsUpgradeToRaw :: WAI.Request -> Bool
}
data SetIpHeader = SIHNone
| SIHFromSocket
| SIHFromHeader
instance Default WaiProxySettings where
def = WaiProxySettings
{ wpsOnExc = defaultOnExc
, wpsTimeout = Nothing
, wpsSetIpHeader = SIHFromSocket
, wpsProcessBody = const Nothing
, wpsUpgradeToRaw = \req ->
(CI.mk <$> lookup "upgrade" (WAI.requestHeaders req)) == Just "websocket"
}
renderHeaders :: WAI.Request -> HT.RequestHeaders -> Builder
renderHeaders req headers
= fromByteString (WAI.requestMethod req)
<> fromByteString " "
<> fromByteString (WAI.rawPathInfo req)
<> fromByteString (WAI.rawQueryString req)
<> (if WAI.httpVersion req == HT.http11
then fromByteString " HTTP/1.1"
else fromByteString " HTTP/1.0")
<> mconcat (map goHeader headers)
<> fromByteString "\r\n\r\n"
where
goHeader (x, y)
= fromByteString "\r\n"
<> fromByteString (CI.original x)
<> fromByteString ": "
<> fromByteString y
tryWebSockets :: WaiProxySettings -> ByteString -> Int -> WAI.Request -> (WAI.Response -> IO b) -> IO b -> IO b
tryWebSockets wps host port req sendResponse fallback
| wpsUpgradeToRaw wps req =
sendResponse $ flip WAI.responseRaw backup $ \fromClientBody toClient ->
DCN.runTCPClient settings $ \server ->
let toServer = DCN.appSink server
fromServer = DCN.appSource server
fromClient = do
mapM_ yield $ L.toChunks $ toLazyByteString headers
let loop = do
bs <- liftIO fromClientBody
unless (S.null bs) $ do
yield bs
loop
loop
toClient' = awaitForever $ liftIO . toClient
headers = renderHeaders req $ fixReqHeaders wps req
in void $ concurrently
(fromClient $$ toServer)
(fromServer $$ toClient')
| otherwise = fallback
where
backup = WAI.responseLBS HT.status500 [("Content-Type", "text/plain")]
"http-reverse-proxy detected WebSockets request, but server does not support responseRaw"
settings = DCN.clientSettings port host
strippedHeaders :: Set HT.HeaderName
strippedHeaders = Set.fromList
["content-length", "transfer-encoding", "accept-encoding", "content-encoding"]
fixReqHeaders :: WaiProxySettings -> WAI.Request -> HT.RequestHeaders
fixReqHeaders wps req =
addXRealIP $ filter (\(key, value) -> not $ key `Set.member` strippedHeaders
|| (key == "connection" && value == "close"))
$ WAI.requestHeaders req
where
fromSocket = (("X-Real-IP", S8.pack $ showSockAddr $ WAI.remoteHost req):)
addXRealIP =
case wpsSetIpHeader wps of
SIHFromSocket -> fromSocket
SIHFromHeader ->
case lookup "x-real-ip" (WAI.requestHeaders req) <|> lookup "X-Forwarded-For" (WAI.requestHeaders req) of
Nothing -> fromSocket
Just ip -> (("X-Real-IP", ip):)
SIHNone -> id
waiProxyToSettings :: (WAI.Request -> IO WaiProxyResponse)
-> WaiProxySettings
-> HC.Manager
-> WAI.Application
waiProxyToSettings getDest wps manager req0 sendResponse = do
edest' <- getDest req0
let edest =
case edest' of
WPRResponse res -> Left $ \_req -> ($ res)
WPRProxyDest pd -> Right (pd, req0)
WPRModifiedRequest req pd -> Right (pd, req)
WPRApplication app -> Left app
case edest of
Left app -> app req0 sendResponse
Right (ProxyDest host port, req) -> tryWebSockets wps host port req sendResponse $ do
let req' = def
{ HC.method = WAI.requestMethod req
, HC.host = host
, HC.port = port
, HC.path = WAI.rawPathInfo req
, HC.queryString = WAI.rawQueryString req
, HC.requestHeaders = fixReqHeaders wps req
, HC.requestBody = body
, HC.redirectCount = 0
, HC.checkStatus = \_ _ _ -> Nothing
, HC.responseTimeout = wpsTimeout wps
}
body =
case WAI.requestBodyLength req of
WAI.KnownLength i -> HC.RequestBodyStream
(fromIntegral i)
($ WAI.requestBody req)
WAI.ChunkedBody -> HC.RequestBodyStreamChunked ($ WAI.requestBody req)
bracket
(try $ HC.responseOpen req' manager)
(either (const $ return ()) HC.responseClose)
$ \ex -> do
case ex of
Left e -> wpsOnExc wps e req sendResponse
Right res -> do
let conduit =
case wpsProcessBody wps $ fmap (const ()) res of
Nothing -> awaitForever (\bs -> yield (Chunk $ fromByteString bs) >> yield Flush)
Just conduit' -> conduit'
src = bodyReaderSource $ HC.responseBody res
sendResponse $ WAI.responseStream
(HC.responseStatus res)
(filter (\(key, _) -> not $ key `Set.member` strippedHeaders) $ HC.responseHeaders res)
(\sendChunk flush -> src $= conduit $$ CL.mapM_ (\mb ->
case mb of
Flush -> flush
Chunk b -> sendChunk b))
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 S8.empty
push bs'
| "\r\n\r\n" `S8.isInfixOf` bs
|| "\n\n" `S8.isInfixOf` bs
|| S8.length bs > 4096 = leftover bs >> return bs
| otherwise = go $ mappend bs
where
bs = front bs'
toHeaders = map toHeader . takeWhile (not . S8.null) . drop 1 . S8.lines
toHeader bs =
(CI.mk key, val)
where
(key, bs') = S.break (== _colon) bs
val = S.takeWhile (/= _cr) $ S.dropWhile isSpace $ S.drop 1 bs'
bodyReaderSource :: MonadIO m => BodyReader -> Source m ByteString
bodyReaderSource br =
loop
where
loop = do
bs <- liftIO $ brRead br
unless (S.null bs) $ do
yield bs
loop