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|
-- |
-- Module : Data.Memory.Encoding.Base64
-- License : BSD-style
-- Maintainer : Vincent Hanquez <vincent@snarc.org>
-- Stability : experimental
-- Portability : unknown
--
-- Low-level Base64 encoding and decoding.
--
-- If you just want to encode or decode some bytes, you probably want to use
-- the "Data.ByteArray.Encoding" module.
--
{-# LANGUAGE MagicHash #-}
{-# LANGUAGE UnboxedTuples #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE Rank2Types #-}
module Data.Memory.Encoding.Base64
( toBase64
, toBase64URL
, toBase64OpenBSD
, unBase64Length
, unBase64LengthUnpadded
, fromBase64
, fromBase64URLUnpadded
, fromBase64OpenBSD
) where
import Data.Memory.Internal.Compat
import Data.Memory.Internal.CompatPrim
import Data.Memory.Internal.Imports
import Data.Bits ((.|.))
import GHC.Prim
import GHC.Word
import Foreign.Storable
import Foreign.Ptr (Ptr)
-- | Transform a number of bytes pointed by @src@ to base64 binary representation in @dst@
--
-- The destination memory need to be of correct size, otherwise it will lead
-- to really bad things.
toBase64 :: Ptr Word8 -> Ptr Word8 -> Int -> IO ()
toBase64 dst src len = toBase64Internal set dst src len True
where
!set = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"#
-- | Transform a number of bytes pointed by @src@ to, URL-safe base64 binary
-- representation in @dst@. The result will be either padded or unpadded,
-- depending on the boolean @padded@ argument.
--
-- The destination memory need to be of correct size, otherwise it will lead
-- to really bad things.
toBase64URL :: Bool -> Ptr Word8 -> Ptr Word8 -> Int -> IO ()
toBase64URL padded dst src len = toBase64Internal set dst src len padded
where
!set = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"#
toBase64OpenBSD :: Ptr Word8 -> Ptr Word8 -> Int -> IO ()
toBase64OpenBSD dst src len = toBase64Internal set dst src len False
where
!set = "./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"#
toBase64Internal :: Addr# -> Ptr Word8 -> Ptr Word8 -> Int -> Bool -> IO ()
toBase64Internal table dst src len padded = loop 0 0
where
eqChar = 0x3d :: Word8
loop i di
| i >= len = return ()
| otherwise = do
a <- peekByteOff src i
b <- if i + 1 >= len then return 0 else peekByteOff src (i+1)
c <- if i + 2 >= len then return 0 else peekByteOff src (i+2)
let (w,x,y,z) = convert3 table a b c
pokeByteOff dst di w
pokeByteOff dst (di+1) x
if i + 1 < len
then
pokeByteOff dst (di+2) y
else
when padded (pokeByteOff dst (di+2) eqChar)
if i + 2 < len
then
pokeByteOff dst (di+3) z
else
when padded (pokeByteOff dst (di+3) eqChar)
loop (i+3) (di+4)
convert3 :: Addr# -> Word8 -> Word8 -> Word8 -> (Word8, Word8, Word8, Word8)
convert3 table (W8# a) (W8# b) (W8# c) =
let !w = narrow8Word# (uncheckedShiftRL# a 2#)
!x = or# (and# (uncheckedShiftL# a 4#) 0x30##) (uncheckedShiftRL# b 4#)
!y = or# (and# (uncheckedShiftL# b 2#) 0x3c##) (uncheckedShiftRL# c 6#)
!z = and# c 0x3f##
in (index w, index x, index y, index z)
where
index :: Word# -> Word8
index idx = W8# (indexWord8OffAddr# table (word2Int# idx))
-- | Get the length needed for the destination buffer for a base64 decoding.
--
-- if the length is not a multiple of 4, Nothing is returned
unBase64Length :: Ptr Word8 -> Int -> IO (Maybe Int)
unBase64Length src len
| len < 1 = return $ Just 0
| (len `mod` 4) /= 0 = return Nothing
| otherwise = do
last1Byte <- peekByteOff src (len - 1)
last2Byte <- peekByteOff src (len - 2)
let dstLen = if last1Byte == eqAscii
then if last2Byte == eqAscii then 2 else 1
else 0
return $ Just $ (len `div` 4) * 3 - dstLen
where
eqAscii :: Word8
eqAscii = fromIntegral (fromEnum '=')
-- | Get the length needed for the destination buffer for an
-- <http://tools.ietf.org/html/rfc4648#section-3.2 unpadded> base64 decoding.
--
-- If the length of the encoded string is a multiple of 4, plus one, Nothing is
-- returned. Any other value can be valid without padding.
unBase64LengthUnpadded :: Int -> Maybe Int
unBase64LengthUnpadded len = case r of
0 -> Just (3*q)
2 -> Just (3*q + 1)
3 -> Just (3*q + 2)
_ -> Nothing
where (q, r) = len `divMod` 4
fromBase64OpenBSD :: Ptr Word8 -> Ptr Word8 -> Int -> IO (Maybe Int)
fromBase64OpenBSD dst src len = fromBase64Unpadded rsetOpenBSD dst src len
fromBase64URLUnpadded :: Ptr Word8 -> Ptr Word8 -> Int -> IO (Maybe Int)
fromBase64URLUnpadded dst src len = fromBase64Unpadded rsetURL dst src len
fromBase64Unpadded :: (Word8 -> Word8) -> Ptr Word8 -> Ptr Word8 -> Int -> IO (Maybe Int)
fromBase64Unpadded rset dst src len = loop 0 0
where loop di i
| i == len = return Nothing
| i == len - 1 = return Nothing -- Shouldn't happen if len is valid
| i == len - 2 = do
a <- peekByteOff src i
b <- peekByteOff src (i+1)
case decode2 a b of
Left ofs -> return $ Just (i + ofs)
Right x -> do
pokeByteOff dst di x
return Nothing
| i == len - 3 = do
a <- peekByteOff src i
b <- peekByteOff src (i+1)
c <- peekByteOff src (i+2)
case decode3 a b c of
Left ofs -> return $ Just (i + ofs)
Right (x,y) -> do
pokeByteOff dst di x
pokeByteOff dst (di+1) y
return Nothing
| otherwise = do
a <- peekByteOff src i
b <- peekByteOff src (i+1)
c <- peekByteOff src (i+2)
d <- peekByteOff src (i+3)
case decode4 a b c d of
Left ofs -> return $ Just (i + ofs)
Right (x,y,z) -> do
pokeByteOff dst di x
pokeByteOff dst (di+1) y
pokeByteOff dst (di+2) z
loop (di + 3) (i + 4)
decode2 :: Word8 -> Word8 -> Either Int Word8
decode2 a b =
case (rset a, rset b) of
(0xff, _ ) -> Left 0
(_ , 0xff) -> Left 1
(ra , rb ) -> Right ((ra `unsafeShiftL` 2) .|. (rb `unsafeShiftR` 4))
decode3 :: Word8 -> Word8 -> Word8 -> Either Int (Word8, Word8)
decode3 a b c =
case (rset a, rset b, rset c) of
(0xff, _ , _ ) -> Left 0
(_ , 0xff, _ ) -> Left 1
(_ , _ , 0xff) -> Left 2
(ra , rb , rc ) ->
let x = (ra `unsafeShiftL` 2) .|. (rb `unsafeShiftR` 4)
y = (rb `unsafeShiftL` 4) .|. (rc `unsafeShiftR` 2)
in Right (x,y)
decode4 :: Word8 -> Word8 -> Word8 -> Word8 -> Either Int (Word8, Word8, Word8)
decode4 a b c d =
case (rset a, rset b, rset c, rset d) of
(0xff, _ , _ , _ ) -> Left 0
(_ , 0xff, _ , _ ) -> Left 1
(_ , _ , 0xff, _ ) -> Left 2
(_ , _ , _ , 0xff) -> Left 3
(ra , rb , rc , rd ) ->
let x = (ra `unsafeShiftL` 2) .|. (rb `unsafeShiftR` 4)
y = (rb `unsafeShiftL` 4) .|. (rc `unsafeShiftR` 2)
z = (rc `unsafeShiftL` 6) .|. rd
in Right (x,y,z)
rsetURL :: Word8 -> Word8
rsetURL (W8# w)
| booleanPrim (w `leWord#` 0xff##) = W8# (indexWord8OffAddr# rsetTable (word2Int# w))
| otherwise = 0xff
where !rsetTable = "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x3e\xff\xff\
\\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\xff\xff\xff\xff\xff\xff\
\\xff\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\
\\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\xff\xff\xff\xff\x3f\
\\xff\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21\x22\x23\x24\x25\x26\x27\x28\
\\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30\x31\x32\x33\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"#
rsetOpenBSD :: Word8 -> Word8
rsetOpenBSD (W8# w)
| booleanPrim (w `leWord#` 0xff##) = W8# (indexWord8OffAddr# rsetTable (word2Int# w))
| otherwise = 0xff
where !rsetTable = "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x00\x01\
\\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x3e\x3f\xff\xff\xff\xff\xff\xff\
\\xff\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\
\\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\xff\xff\xff\xff\xff\
\\xff\x1c\x1d\x1e\x1f\x20\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2a\
\\x2b\x2c\x2d\x2e\x2f\x30\x31\x32\x33\x34\x35\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"#
-- | convert from base64 in @src@ to binary in @dst@, using the number of bytes specified
--
-- the user should use unBase64Length to compute the correct length, or check that
-- the length specification is proper. no check is done here.
fromBase64 :: Ptr Word8 -> Ptr Word8 -> Int -> IO (Maybe Int)
fromBase64 dst src len
| len == 0 = return Nothing
| otherwise = loop 0 0
where loop di i
| i == (len-4) = do
a <- peekByteOff src i
b <- peekByteOff src (i+1)
c <- peekByteOff src (i+2)
d <- peekByteOff src (i+3)
let (nbBytes, c',d') =
case (c,d) of
(0x3d, 0x3d) -> (2, 0x30, 0x30)
(0x3d, _ ) -> (0, c, d) -- invalid: automatically 'c' will make it error out
(_ , 0x3d) -> (1, c, 0x30)
(_ , _ ) -> (0 :: Int, c, d)
case decode4 a b c' d' of
Left ofs -> return $ Just (i + ofs)
Right (x,y,z) -> do
pokeByteOff dst di x
when (nbBytes < 2) $ pokeByteOff dst (di+1) y
when (nbBytes < 1) $ pokeByteOff dst (di+2) z
return Nothing
| otherwise = do
a <- peekByteOff src i
b <- peekByteOff src (i+1)
c <- peekByteOff src (i+2)
d <- peekByteOff src (i+3)
case decode4 a b c d of
Left ofs -> return $ Just (i + ofs)
Right (x,y,z) -> do
pokeByteOff dst di x
pokeByteOff dst (di+1) y
pokeByteOff dst (di+2) z
loop (di + 3) (i + 4)
decode4 :: Word8 -> Word8 -> Word8 -> Word8 -> Either Int (Word8, Word8, Word8)
decode4 a b c d =
case (rset a, rset b, rset c, rset d) of
(0xff, _ , _ , _ ) -> Left 0
(_ , 0xff, _ , _ ) -> Left 1
(_ , _ , 0xff, _ ) -> Left 2
(_ , _ , _ , 0xff) -> Left 3
(ra , rb , rc , rd ) ->
let x = (ra `unsafeShiftL` 2) .|. (rb `unsafeShiftR` 4)
y = (rb `unsafeShiftL` 4) .|. (rc `unsafeShiftR` 2)
z = (rc `unsafeShiftL` 6) .|. rd
in Right (x,y,z)
rset :: Word8 -> Word8
rset (W8# w)
| booleanPrim (w `leWord#` 0xff##) = W8# (indexWord8OffAddr# rsetTable (word2Int# w))
| otherwise = 0xff
!rsetTable = "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x3e\xff\xff\xff\x3f\
\\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\xff\xff\xff\xff\xff\xff\
\\xff\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\
\\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\xff\xff\xff\xff\xff\
\\xff\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21\x22\x23\x24\x25\x26\x27\x28\
\\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30\x31\x32\x33\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"#
|
