module Snap.Util.GZip
( withCompression
, withCompression' ) where
import Blaze.ByteString.Builder
import qualified Codec.Compression.GZip as GZip
import qualified Codec.Compression.Zlib as Zlib
import Control.Concurrent
import Control.Applicative hiding (many)
import Control.Exception
import Control.Monad
import Control.Monad.Trans
import Data.Attoparsec.Char8 hiding (Done)
import qualified Data.ByteString.Lazy.Char8 as L
import Data.ByteString.Char8 (ByteString)
import Data.Maybe
import qualified Data.Set as Set
import Data.Set (Set)
import Data.Typeable
import Prelude hiding (catch, takeWhile)
import Snap.Internal.Debug
import Snap.Internal.Parsing
import Snap.Iteratee
import qualified Snap.Iteratee as I
import Snap.Types
withCompression :: MonadSnap m
=> m a
-> m ()
withCompression = withCompression' compressibleMimeTypes
withCompression' :: MonadSnap m
=> Set ByteString
-> m a
-> m ()
withCompression' mimeTable action = do
_ <- action
resp <- getResponse
when (not $ isJust $ getHeader "Content-Encoding" resp) $ do
let mbCt = getHeader "Content-Type" resp
debug $ "withCompression', content-type is " ++ show mbCt
case mbCt of
(Just ct) -> when (Set.member ct mimeTable) chkAcceptEncoding
_ -> return $! ()
getResponse >>= finishWith
where
chkAcceptEncoding = do
req <- getRequest
debug $ "checking accept-encoding"
let mbAcc = getHeader "Accept-Encoding" req
debug $ "accept-encoding is " ++ show mbAcc
let s = fromMaybe "" mbAcc
types <- liftIO $ parseAcceptEncoding s
chooseType types
chooseType [] = return $! ()
chooseType ("gzip":_) = gzipCompression "gzip"
chooseType ("compress":_) = compressCompression "compress"
chooseType ("x-gzip":_) = gzipCompression "x-gzip"
chooseType ("x-compress":_) = compressCompression "x-compress"
chooseType (_:xs) = chooseType xs
compressibleMimeTypes :: Set ByteString
compressibleMimeTypes = Set.fromList [ "application/x-font-truetype"
, "application/x-javascript"
, "text/css"
, "text/html"
, "text/javascript"
, "text/plain"
, "text/xml" ]
gzipCompression :: MonadSnap m => ByteString -> m ()
gzipCompression ce = modifyResponse f
where
f = setHeader "Content-Encoding" ce .
setHeader "Vary" "Accept-Encoding" .
clearContentLength .
modifyResponseBody gcompress
compressCompression :: MonadSnap m => ByteString -> m ()
compressCompression ce = modifyResponse f
where
f = setHeader "Content-Encoding" ce .
setHeader "Vary" "Accept-Encoding" .
clearContentLength .
modifyResponseBody ccompress
gcompress :: forall a . Enumerator Builder IO a
-> Enumerator Builder IO a
gcompress = compressEnumerator GZip.compress
ccompress :: forall a . Enumerator Builder IO a
-> Enumerator Builder IO a
ccompress = compressEnumerator Zlib.compress
compressEnumerator :: forall a .
(L.ByteString -> L.ByteString)
-> Enumerator Builder IO a
-> Enumerator Builder IO a
compressEnumerator compFunc enum' origStep = do
let iter = joinI $ I.map fromByteString origStep
step <- lift $ runIteratee iter
writeEnd <- liftIO $ newChan
readEnd <- liftIO $ newChan
tid <- liftIO $ forkIO $ threadProc readEnd writeEnd
let enum = mapEnum fromByteString toByteString enum'
let outEnum = enum (f readEnd writeEnd tid step)
mapIter toByteString fromByteString outEnum
where
streamFinished :: Stream ByteString -> Bool
streamFinished EOF = True
streamFinished (Chunks _) = False
consumeSomeOutput :: Chan (Either SomeException (Stream ByteString))
-> Step ByteString IO a
-> Iteratee ByteString IO (Step ByteString IO a)
consumeSomeOutput writeEnd step = do
e <- lift $ isEmptyChan writeEnd
if e
then return step
else do
ech <- lift $ readChan writeEnd
either throwError
(\ch -> do
step' <- checkDone (\k -> lift $ runIteratee $ k ch)
step
consumeSomeOutput writeEnd step')
ech
consumeRest :: Chan (Either SomeException (Stream ByteString))
-> Step ByteString IO a
-> Iteratee ByteString IO a
consumeRest writeEnd step = do
ech <- lift $ readChan writeEnd
either throwError
(\ch -> do
step' <- checkDone (\k -> lift $ runIteratee $ k ch) step
if (streamFinished ch)
then returnI step'
else consumeRest writeEnd step')
ech
f _ _ _ (Error e) = Error e
f _ _ _ (Yield x _) = Yield x EOF
f readEnd writeEnd tid st@(Continue k) = Continue $ \ch ->
case ch of
EOF -> do
lift $ writeChan readEnd Nothing
x <- consumeRest writeEnd st
lift $ killThread tid
return x
(Chunks xs) -> do
mapM_ (lift . writeChan readEnd . Just) xs
step' <- consumeSomeOutput writeEnd (Continue k)
returnI $ f readEnd writeEnd tid step'
threadProc :: Chan (Maybe ByteString)
-> Chan (Either SomeException (Stream ByteString))
-> IO ()
threadProc readEnd writeEnd = do
stream <- getChanContents readEnd
let bs = L.fromChunks $ streamToChunks stream
let output = L.toChunks $ compFunc bs
runIt output `catch` \(e::SomeException) ->
writeChan writeEnd $ Left e
where
runIt (x:xs) = do
writeChan writeEnd (toChunk x) >> runIt xs
runIt [] = do
writeChan writeEnd $ Right EOF
streamToChunks [] = []
streamToChunks (Nothing:_) = []
streamToChunks ((Just x):xs) = x:(streamToChunks xs)
toChunk = Right . Chunks . (:[])
acceptParser :: Parser [ByteString]
acceptParser = do
xs <- option [] $ (:[]) <$> encoding
ys <- many (char ',' *> encoding)
endOfInput
return $ xs ++ ys
where
encoding = skipSpace *> c <* skipSpace
c = do
x <- coding
option () qvalue
return x
qvalue = do
skipSpace
char ';'
skipSpace
char 'q'
skipSpace
char '='
float
return ()
coding = string "*" <|> takeWhile isCodingChar
isCodingChar ch = isDigit ch || isAlpha_ascii ch || ch == '-' || ch == '_'
float = takeWhile isDigit >>
option () (char '.' >> takeWhile isDigit >> pure ())
data BadAcceptEncodingException = BadAcceptEncodingException
deriving (Typeable)
instance Show BadAcceptEncodingException where
show BadAcceptEncodingException = "bad 'accept-encoding' header"
instance Exception BadAcceptEncodingException
parseAcceptEncoding :: ByteString -> IO [ByteString]
parseAcceptEncoding s =
case r of
Left _ -> throwIO BadAcceptEncodingException
Right x -> return x
where
r = fullyParse s acceptParser