1 files changed, 16 insertions, 3 deletions

diff --git a/src/Network/Tox/Crypto/Transport.hs b/src/Network/Tox/Crypto/Transport.hs
index 35b4904e..21100c86 100644
--- a/src/Network/Tox/Crypto/Transport.hs
+++ b/src/Network/Tox/Crypto/Transport.hs
@@ -48,6 +48,9 @@ module Network.Tox.Crypto.Transport
     , isIndirectGrpChat
     , LossyOrLossless(..)
     , lossyness
+    , fromEnum8
+    , fromEnum16
+    , toEnum8
     ) where
 
 import Crypto.Tox
@@ -61,6 +64,7 @@ import Data.ByteString as B
 import Data.Maybe
 import Data.Monoid
 import Data.Word
+import Data.Bits
 import Crypto.Hash
 import Control.Lens
 import Data.Text as T
@@ -418,14 +422,23 @@ class AsWord16 a where
 
 toEnum8 ::Enum a => Word8 -> a
 toEnum8 = toEnum . fromIntegral
+fromEnum8 :: Enum a => a -> Word8
+fromEnum8 = fromIntegral . fromEnum
+
 fromEnum16 :: Enum a => a -> Word16
 fromEnum16 = fromIntegral . fromEnum
 
+
+-- MessageType, for our client keep it inside 16 bits
+-- but we should extend it to 32 or even 64 on the wire.
+-- Bits: 000000glxxxxxxxx, x = message id or extension specific, l = if extended, lossy/lossless, g = if extended, nongroup/group
+--      (at least one bit set in high byte means extended, if none but the g flag and possibly l flag, assume default grp extension)
 instance AsWord16 MessageType where
     toWord16 (Msg msgID) = fromIntegral (fromIntegral (fromEnum16 msgID) :: Word8)
-    toWord16 (GrpMsg lsy msgName) = 256 * (fromEnum16 lsy + 1) + fromIntegral (fromIntegral (fromEnum msgName) :: Word8)
-    fromWord16 x | x < 256 = Msg (toEnum $ fromIntegral x)
-    fromWord16 x           = GrpMsg (toEnum8 ((fromIntegral (x `div` 256)) - 1)) (toEnum8 (fromIntegral x :: Word8))
+    toWord16 (GrpMsg lsy msgName) = 512 + 256 * (fromEnum16 lsy) + fromIntegral (fromIntegral (fromEnum msgName) :: Word8)
+    fromWord16 x | x < 256                          = Msg (toEnum $ fromIntegral x)
+    fromWord16 x | x < 1024, x .|. 0x0200 == 0x0200 = GrpMsg (toEnum8 (fromIntegral ((x - 512) `div` 256))) (toEnum8 (fromIntegral x :: Word8))
+    fromWord16 x = error "Not clear how to convert Word16 to MessageType"
 
 word16 :: (Functor f, AsWord16 x) => (Word16 -> f Word16) -> (x -> f x)
 word16  = lens toWord16 (\_ x -> fromWord16 x)