85 lines
2.7 KiB
Haskell
85 lines
2.7 KiB
Haskell
{-# LANGUAGE ScopedTypeVariables #-}
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module Network.TLS.Util
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( sub
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, takelast
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, partition3
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, partition6
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, fromJust
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, and'
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, (&&!)
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, bytesEq
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, fmapEither
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, catchException
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) where
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import Data.List (foldl')
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import Network.TLS.Struct (Bytes)
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import qualified Data.ByteString as B
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import Control.Exception (fromException)
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import qualified Control.Exception as E
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sub :: Bytes -> Int -> Int -> Maybe Bytes
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sub b offset len
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| B.length b < offset + len = Nothing
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| otherwise = Just $ B.take len $ snd $ B.splitAt offset b
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takelast :: Int -> Bytes -> Maybe Bytes
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takelast i b
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| B.length b >= i = sub b (B.length b - i) i
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| otherwise = Nothing
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partition3 :: Bytes -> (Int,Int,Int) -> Maybe (Bytes, Bytes, Bytes)
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partition3 bytes (d1,d2,d3)
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| any (< 0) l = Nothing
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| sum l /= B.length bytes = Nothing
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| otherwise = Just (p1,p2,p3)
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where l = [d1,d2,d3]
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(p1, r1) = B.splitAt d1 bytes
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(p2, r2) = B.splitAt d2 r1
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(p3, _) = B.splitAt d3 r2
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partition6 :: Bytes -> (Int,Int,Int,Int,Int,Int) -> Maybe (Bytes, Bytes, Bytes, Bytes, Bytes, Bytes)
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partition6 bytes (d1,d2,d3,d4,d5,d6) = if B.length bytes < s then Nothing else Just (p1,p2,p3,p4,p5,p6)
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where s = sum [d1,d2,d3,d4,d5,d6]
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(p1, r1) = B.splitAt d1 bytes
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(p2, r2) = B.splitAt d2 r1
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(p3, r3) = B.splitAt d3 r2
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(p4, r4) = B.splitAt d4 r3
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(p5, r5) = B.splitAt d5 r4
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(p6, _) = B.splitAt d6 r5
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fromJust :: String -> Maybe a -> a
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fromJust what Nothing = error ("fromJust " ++ what ++ ": Nothing") -- yuck
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fromJust _ (Just x) = x
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-- | This is a strict version of and
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and' :: [Bool] -> Bool
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and' l = foldl' (&&!) True l
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-- | This is a strict version of &&.
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(&&!) :: Bool -> Bool -> Bool
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True &&! True = True
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True &&! False = False
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False &&! True = False
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False &&! False = False
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-- | verify that 2 bytestrings are equals.
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-- it's a non lazy version, that will compare every bytes.
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-- arguments with different length will bail out early
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bytesEq :: Bytes -> Bytes -> Bool
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bytesEq b1 b2
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| B.length b1 /= B.length b2 = False
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| otherwise = and' $ B.zipWith (==) b1 b2
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fmapEither :: (a -> b) -> Either l a -> Either l b
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fmapEither f e = case e of
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Left l -> Left l
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Right r -> Right (f r)
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catchException :: IO a -> (E.SomeException -> IO a) -> IO a
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catchException f handler = E.catchJust filterExn f handler
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where filterExn :: E.SomeException -> Maybe E.SomeException
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filterExn e = case fromException e of
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Just (_ :: E.AsyncException) -> Nothing
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Nothing -> Just e
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