--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/netserver/Codec/Binary/Base64.hs Sun Jan 25 13:48:41 2009 +0000
@@ -0,0 +1,113 @@
+-- |
+-- Module : Codec.Binary.Base64
+-- Copyright : (c) 2007 Magnus Therning
+-- License : BSD3
+--
+-- Implemented as specified in RFC 4648
+-- (<http://tools.ietf.org/html/rfc4648>).
+--
+-- Further documentation and information can be found at
+-- <http://www.haskell.org/haskellwiki/Library/Data_encoding>.
+module Codec.Binary.Base64
+ ( encode
+ , decode
+ , decode'
+ , chop
+ , unchop
+ ) where
+
+import Control.Monad
+import Data.Array
+import Data.Bits
+import Data.Maybe
+import Data.Word
+import qualified Data.Map as M
+
+-- {{{1 enc/dec map
+_encMap =
+ [ (0, 'A'), (1, 'B'), (2, 'C'), (3, 'D'), (4, 'E')
+ , (5, 'F') , (6, 'G'), (7, 'H'), (8, 'I'), (9, 'J')
+ , (10, 'K'), (11, 'L'), (12, 'M'), (13, 'N'), (14, 'O')
+ , (15, 'P'), (16, 'Q'), (17, 'R'), (18, 'S'), (19, 'T')
+ , (20, 'U'), (21, 'V'), (22, 'W'), (23, 'X'), (24, 'Y')
+ , (25, 'Z'), (26, 'a'), (27, 'b'), (28, 'c'), (29, 'd')
+ , (30, 'e'), (31, 'f'), (32, 'g'), (33, 'h'), (34, 'i')
+ , (35, 'j'), (36, 'k'), (37, 'l'), (38, 'm'), (39, 'n')
+ , (40, 'o'), (41, 'p'), (42, 'q'), (43, 'r'), (44, 's')
+ , (45, 't'), (46, 'u'), (47, 'v'), (48, 'w'), (49, 'x')
+ , (50, 'y'), (51, 'z'), (52, '0'), (53, '1'), (54, '2')
+ , (55, '3'), (56, '4'), (57, '5'), (58, '6'), (59, '7')
+ , (60, '8'), (61, '9'), (62, '+'), (63, '/') ]
+
+-- {{{1 encodeArray
+encodeArray :: Array Word8 Char
+encodeArray = array (0, 64) _encMap
+
+-- {{{1 decodeMap
+decodeMap :: M.Map Char Word8
+decodeMap = M.fromList [(snd i, fst i) | i <- _encMap]
+
+-- {{{1 encode
+-- | Encode data.
+encode :: [Word8]
+ -> String
+encode = let
+ pad n = take n $ repeat 0
+ enc [] = ""
+ enc l@[o] = (++ "==") . take 2 .enc $ l ++ pad 2
+ enc l@[o1, o2] = (++ "=") . take 3 . enc $ l ++ pad 1
+ enc (o1:o2:o3:os) = let
+ i1 = o1 `shiftR` 2
+ i2 = (o1 `shiftL` 4 .|. o2 `shiftR` 4) .&. 0x3f
+ i3 = (o2 `shiftL` 2 .|. o3 `shiftR` 6) .&. 0x3f
+ i4 = o3 .&. 0x3f
+ in (foldr (\ i s -> (encodeArray ! i) : s) "" [i1, i2, i3, i4]) ++ enc os
+ in enc
+
+-- {{{1 decode
+-- | Decode data (lazy).
+decode' :: String
+ -> [Maybe Word8]
+decode' = let
+ pad n = take n $ repeat $ Just 0
+ dec [] = []
+ dec l@[Just eo1, Just eo2] = take 1 . dec $ l ++ pad 2
+ dec l@[Just eo1, Just eo2, Just eo3] = take 2 . dec $ l ++ pad 1
+ dec (Just eo1:Just eo2:Just eo3:Just eo4:eos) = let
+ o1 = eo1 `shiftL` 2 .|. eo2 `shiftR` 4
+ o2 = eo2 `shiftL` 4 .|. eo3 `shiftR` 2
+ o3 = eo3 `shiftL` 6 .|. eo4
+ in Just o1:Just o2:Just o3:(dec eos)
+ dec _ = [Nothing]
+ in
+ dec . map (flip M.lookup decodeMap) . takeWhile (/= '=')
+
+-- | Decode data (strict).
+decode :: String
+ -> Maybe [Word8]
+decode = sequence . decode'
+
+-- {{{1 chop
+-- | Chop up a string in parts.
+--
+-- The length given is rounded down to the nearest multiple of 4.
+--
+-- /Notes:/
+--
+-- * PEM requires lines that are 64 characters long.
+--
+-- * MIME requires lines that are at most 76 characters long.
+chop :: Int -- ^ length of individual lines
+ -> String
+ -> [String]
+chop n "" = []
+chop n s = let
+ enc_len | n < 4 = 4
+ | otherwise = n `div` 4 * 4
+ in (take enc_len s) : chop n (drop enc_len s)
+
+-- {{{1 unchop
+-- | Concatenate the strings into one long string.
+unchop :: [String]
+ -> String
+unchop = foldr (++) ""