-- |
-- Module    : Network.Pcap.Streaming
-- Copyright : (c) Colin Woodbury, 2018 - 2023
-- License   : BSD3
-- Maintainer: Colin Woodbury <colin@fosskers.ca>
--
-- A streaming interface to the <http://hackage.haskell.org/package/pcap-0.4.5.2 pcap>
-- Haskell library, which itself is a binding to /libpcap/. Humbly adapted from
-- <http://hackage.haskell.org/package/pcap-conduit pcap-conduit> by Austin Seipp.

module Network.Pcap.Streaming
  ( Packet(..)
  , PktHdr(..)
  , offline
  , online
  ) where

import           Control.Monad.Trans.Resource
import qualified Data.Attoparsec.ByteString.Streaming as A
import           Data.Int (Int64)
import           Network.Pcap
import           Network.Pcap.Streaming.Internal
import           Streaming
import qualified Streaming.ByteString as Q
import qualified Streaming.Prelude as P

---

-- | Read `Packet`s from some file dump. Uses a custom parser, not /libpcap/.
--
-- /SPECIALIZE/d for @ResourceT IO@.
offline :: MonadResource m => FilePath -> Stream (Of Packet) m ()
offline = void . A.parsed packetP . Q.drop 24 . Q.readFile
{-# SPECIALIZE offline :: FilePath -> Stream (Of Packet) (ResourceT IO) () #-}

-- | Read `Packet`s from some network device. See `Network.Pcap.openLive` for a
-- description of each argument.
--
-- /SPECIALIZE/d for @IO@.
online :: MonadIO m => String -> Int -> Bool -> Int64 -> Stream (Of Packet) m ()
online n s p t = liftIO (openLive n s p t) >>= packets
{-# SPECIALIZE online :: String -> Int -> Bool -> Int64 -> Stream (Of Packet) IO () #-}

packets :: MonadIO m => PcapHandle -> Stream (Of Packet) m ()
packets h = do
  (hdr,bs) <- liftIO (nextBS h)
  if hdrCaptureLength hdr == 0 then pure () else P.yield (Packet hdr bs) *> packets h
{-# SPECIALIZE packets :: PcapHandle -> Stream (Of Packet) IO () #-}