38 lines
1.1 KiB
Haskell
38 lines
1.1 KiB
Haskell
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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) where
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import Network.TLS.Struct (Bytes)
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import qualified Data.ByteString as B
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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) = if B.length bytes /= s then Nothing else Just (p1,p2,p3)
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where
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s = sum [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
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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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