Deserialize Macaroons

- Refactor serialization/deserialization into its own module
- Refactor tests

2 files changed, 85 insertions, 35 deletions

diff --git a/src/Crypto/Macaroon.hs b/src/Crypto/Macaroon.hs
index 07043f7..36aecf9 100644
--- a/src/Crypto/Macaroon.hs
+++ b/src/Crypto/Macaroon.hs
@@ -42,21 +42,14 @@ module Crypto.Macaroon (
     , inspect
     , addFirstPartyCaveat
     , addThirdPartyCaveat
-
-    -- * Prepare Macaroons for transfer
-    , serialize
     ) where
 
 import           Crypto.Cipher.AES
 import           Crypto.Hash
-import           Data.Char
 import           Data.Byteable
 import qualified Data.ByteString            as BS
 import qualified Data.ByteString.Base64.URL as B64
 import qualified Data.ByteString.Char8      as B8
-import           Data.Hex
-import           Data.Word
-import           Data.Serialize
 
 import           Crypto.Macaroon.Internal
 
@@ -82,34 +75,6 @@ caveatVId = vid
 inspect :: Macaroon -> String
 inspect = show
 
--- | Serialize a macaroon in an URL-safe Base64 encoding
-serialize :: Macaroon -> BS.ByteString
-serialize m = B8.filter (/= '=') . B64.encode $ packets
-  where
-    packets = BS.concat [ putPacket "location" (location m)
-                        , putPacket "identifier" (identifier m)
-                        , caveatPackets
-                        , putPacket "signature" (signature m)
-                        ]
-    caveatPackets = BS.concat $ map (cavPacket (location m)) (caveats m)
-    cavPacket loc c | cl c == loc && vid c == BS.empty = putPacket "cid" (cid c)
-                    | otherwise = BS.concat [ putPacket "cid" (cid c)
-                                            , putPacket "vid" (vid c)
-                                            , putPacket "cl" (cl c)
-                                            ]
-    putPacket key dat = BS.concat [
-        B8.map toLower . hex . encode $ (fromIntegral size :: Word16)
-        , key
-        , " "
-        , dat
-        , "\n"
-        ]
-      where
-        size = 4 + 2 + BS.length key + BS.length dat
-
-
-
-
 -- | Add a first party Caveat to a Macaroon, with its identifier
 addFirstPartyCaveat :: Key -> Macaroon -> Macaroon
 addFirstPartyCaveat ident m = addCaveat (location m) ident BS.empty m
diff --git a/src/Crypto/Macaroon/Serializer/Base64.hs b/src/Crypto/Macaroon/Serializer/Base64.hs
new file mode 100644
index 0000000..6fc8fcb
--- /dev/null
+++ b/src/Crypto/Macaroon/Serializer/Base64.hs
@@ -0,0 +1,85 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-|
+Module      : Crypto.Macaroon.Serializer.Base64
+Copyright   : (c) 2015 Julien Tanguy
+License     : BSD3
+
+Maintainer  : julien.tanguy@jhome.fr
+Stability   : experimental
+Portability : portable
+
+Base64 serializer/deserializer
+
+-}
+module Crypto.Macaroon.Serializer.Base64 (
+        serialize
+      , deserialize
+      ) where
+
+import Control.Applicative
+import Control.Monad
+import qualified Data.ByteString            as BS
+import qualified Data.ByteString.Base64.URL as B64
+import qualified Data.ByteString.Char8      as B8
+import Data.Attoparsec.ByteString
+import qualified Data.Attoparsec.ByteString.Char8 as A8
+import           Data.Bits
+import           Data.Char
+import           Data.Hex
+import           Data.Int
+import           Data.List
+import           Data.Maybe
+import           Data.Word
+import           Data.Serialize
+import Crypto.Macaroon.Internal
+
+
+-- | Serialize a macaroon in an URL-safe Base64 encoding
+serialize :: Macaroon -> BS.ByteString
+serialize m = B8.filter (/= '=') . B64.encode . runPut $ do
+    packetize "location" (location m)
+    packetize "identifier" (identifier m)
+    forM_ (caveats m) $ \c -> do
+        packetize "cid" (cid c)
+        unless (cl c == location m && vid c == BS.empty) $ do
+            packetize "vid" (vid c)
+            packetize "cl" (cl c)
+    packetize "signature" (signature m)
+
+packetize :: BS.ByteString -> BS.ByteString -> Put
+packetize key dat = do
+    let size = 4 + 2 + BS.length key + BS.length dat
+    putByteString $ B8.map toLower . hex . encode $ (fromIntegral size :: Word16)
+    putByteString key
+    putByteString " "
+    putByteString dat
+    putByteString "\n"
+
+deserialize :: BS.ByteString -> Either String Macaroon
+deserialize = parseOnly macaroon . B64.decodeLenient
+
+
+macaroon :: Parser Macaroon
+macaroon = do
+    ps <- many packet <* endOfInput
+    let ([("location",l),("identifier",i)],ps') = splitAt 2 ps
+    let (caveats,sig) = splitAt (length ps' - 1) ps'
+    let [("signature",s)] = sig
+    return $ MkMacaroon l i (map (mkCaveat l) (groupBy splitCavs caveats)) s
+  where
+    mkCaveat _ [("cid",c),("vid",v),("cl",l)] = MkCaveat c v l
+    mkCaveat l [("cid",c)] = MkCaveat c BS.empty l
+    mkCaveat _ _ = error "Malformed caveat"
+    splitCavs _ ("cid",_) = False
+    splitCavs _ _ = True
+
+packet :: Parser (BS.ByteString, BS.ByteString)
+packet = do
+    size <- A8.take 4
+    case A8.parseOnly (A8.hexadecimal :: Parser Word16) size of
+        Left e -> fail e
+        Right s -> do
+            bs <- A8.take (fromIntegral $ s - 4)
+            let (key, dat) = B8.break (== ' ') bs
+            return (key, B8.tail $ B8.init dat)
+