transport-over-mix/reference/Transport/Protocol.hs

{-# LANGUAGE StrictData, DerivingVia #-}
module Transport.Protocol where

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import Data.Word

import Data.ByteString      (ByteString    ) ; import qualified Data.ByteString      as B
import Data.ByteString.Lazy (LazyByteString) ; import qualified Data.ByteString.Lazy as L

import Transport.Types
import Transport.Misc

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data SessionControl
  = InitialMessage AppProtocol          -- ^ the first message estabilishing a connection
  | Continue                            -- ^ proceed normally
  | CloseSession                        -- ^ closing down the session
  deriving (Eq,Show)

-- | Application layer protocol
data AppProtocol = MkAppProtocol
  { appProtocolName :: String           -- ^ name of the application layer protocol
  , appProtocolInfo :: ByteString       -- ^ additional protocol-dependent info (eg. key exchange)
  }
  deriving (Eq,Show)

data AckEntry
  = MsgReceived    MsgIdx               -- ^ message received intact
  | MsgFailed      MsgIdx FailReason    -- ^ message failed (eg. decoding, checksum or timeout)
  | NeedMoreChunks MsgIdx ChunkIdx      -- ^ we need more chunks 
  | ResendChunks   MsgIdx [ChunkIdx]    -- ^ re-transmit particular chunks
  deriving (Eq,Show)

data FailReason
  = FailTimeout             -- ^ couldn't decode within the expected time
  | FailDecode              -- ^ erasure code decoding failed
  | FailChecksum            -- ^ checksum failed
  | NotYetImplemented       -- ^ we haven't implemented the feature
  deriving (Eq,Show,Enum)

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data TransportVersion
  = V1
  deriving (Eq,Show,Enum)

data TransportMeta = MkTransportMeta
  { _transVersion   :: TransportVersion   -- ^ protocol version 
  , _transControl   :: SessionControl     -- ^ where we are in the session
  , _transReqSURBs  :: Int                -- ^ how many more SURBs we need 
  , _transAcks      :: [AckEntry]         -- ^ status of previous messages
  }
  deriving (Eq,Show)

data Message = MkMessage
  { _msgMeta      :: TransportMeta     -- ^ transport layer metadata
  , _msgSURBs     :: [SURB]            -- ^ the new SURBs we send
  , _msgPayload   :: ByteString        -- ^ the actual payload
  }
  deriving Eq

instance Show Message where
  show (MkMessage meta surbs payload) = 
    "MkMessage (" ++ show meta ++ ") " ++ show surbs ++ " " ++ showByteString payload

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