diff --git a/Readme.md b/Readme.md --- a/Readme.md +++ b/Readme.md @@ -15,19 +15,19 @@ Implementation ============== -* `n` is randomly generated for each packet. -* `n` is bounded by a maximum `r`, configurable by the `--randomness` argument. -* To reduce overhead, `n` is set to 0 whenever `m` is greater then a - threshold `b`, configurable by the `--bound` argument. +* `n` is deduced from a randomly generated `i = n + m` for each packet. +* When a random `i` is less then `m`, payload is split to `p1` and `p2` to satisfy the constrain, where the length of `p1` is equal to `i` and `p1 + p2 = payload`. `p2` will be sent in the next iteration by the same algorithm. +* `i` is bounded by a maximum `r`, configurable by the `--randomnessInBytes` argument. +* To reduce overhead, `n` is set to `0` whenever `m` is greater then `r`. Usage ===== * local: - need-obfs --localHost TEXT --localPort INTEGER --remoteHost TEXT --remotePort INTEGER + neko-obfs --localHost TEXT --localPort INTEGER --remoteHost TEXT --remotePort INTEGER * remote: - neko-obfs --remote --remoteHost TEXT --remotePort INTEGER --forwardHost TEXT --forwardPort INTEGER + neko-obfs --role remote --remoteHost TEXT --remotePort INTEGER --forwardHost TEXT --forwardPort INTEGER * This tunnel should be used inside an encrypted tunnel. * For example: diff --git a/neko-obfs.cabal b/neko-obfs.cabal --- a/neko-obfs.cabal +++ b/neko-obfs.cabal @@ -2,7 +2,7 @@ -- documentation, see http://haskell.org/cabal/users-guide/ name: neko-obfs -version: 0.1.0.1 +version: 0.1.0.2 synopsis: a TCP tunnel with packet length obfuscation description: Just another tool that helps accessing the internet license: Apache-2.0 diff --git a/src/Main.hs b/src/Main.hs --- a/src/Main.hs +++ b/src/Main.hs @@ -4,10 +4,11 @@ import Helper ((-), log) import Prelude hiding ((-), log) +import qualified Prelude as Prelude import Control.Concurrent.Async (async, waitAnyCatchCancel, waitEitherCancel) import Control.Lens -import Control.Monad (replicateM_, join) +import Control.Monad (replicateM_, join, when) import Control.Monad.IO.Class (MonadIO(..)) import Control.Monad.Trans.State.Strict (runStateT) import Data.Attoparsec.ByteString (parse, maybeResult) @@ -28,29 +29,69 @@ import Pipes.Safe import System.Random (randomIO) import Options.Generic +import System.IO (hSetBuffering, stdin, stdout, BufferMode(LineBuffering)) import Options (toConfig) import Parser import Type -obfsEncode :: (MonadIO m) => Integer -> Integer -> Pipe ByteString ByteString m a -obfsEncode bound randomness = do +obfsEncode :: (MonadIO m) => Bool -> Integer -> Pipe ByteString ByteString m a +obfsEncode debug randomness = do for cat - \x -> do let payloadLen = (fromIntegral - B.length x) + if (payloadLen >= fromIntegral randomness) + then do + let paddingLen = 0 + let chunk = + view strict - Builder.toLazyByteString - + Builder.word32BE paddingLen + <> Builder.byteString + (BC.replicate (fromIntegral paddingLen) - '.') + <> Builder.word32BE payloadLen + <> Builder.byteString x - randomLen <- - if (payloadLen > fromIntegral bound) - then pure 0 - else liftIO - randomIO <&> (`mod` fromIntegral randomness) + when debug - log - "E: " <> (T.pack - show - B.length chunk) + yield chunk + else + randomLenCheckLoop x + where + randomLenCheckLoop payload = do + let payloadLen = (fromIntegral - B.length payload) + randomLen <- liftIO - randomIO <&> (`mod` fromIntegral randomness) + if (payloadLen <= randomLen) + then + do + let paddingLen = randomLen Prelude.- payloadLen + let chunk = + view strict - Builder.toLazyByteString - + Builder.word32BE paddingLen + <> Builder.byteString + (BC.replicate (fromIntegral paddingLen) - '.') + <> Builder.word32BE payloadLen + <> Builder.byteString payload - yield - view strict - Builder.toLazyByteString - - Builder.word32BE randomLen - <> Builder.byteString (BC.replicate (fromIntegral randomLen) - 'a') - <> Builder.word32BE payloadLen - <> Builder.byteString x + when debug - log - "E: " <> (T.pack - show - B.length chunk) + yield chunk + else + do + let paddingLen = 0 + (now, next) = B.splitAt (fromIntegral randomLen) payload + let chunk = + view strict - Builder.toLazyByteString - + Builder.word32BE paddingLen + <> Builder.byteString + (BC.replicate (fromIntegral paddingLen) - '.') + <> Builder.word32BE (fromIntegral - B.length now) + <> Builder.byteString now + when debug - log - "E: " <> (T.pack - show - B.length chunk) + yield chunk + + randomLenCheckLoop next + + obfsDecode :: (MonadIO m) => Producer ByteString m a -> (ByteString -> m ()) -> m () obfsDecode pull sink = loop pull where @@ -65,12 +106,15 @@ main :: IO () main = do + hSetBuffering stdin LineBuffering + hSetBuffering stdout LineBuffering + config <- getRecord "a TCP tunnel with packet length obfuscation" <&> toConfig log - T.pack - show config - let mtu = 4096 - timeout = fromIntegral - config ^. timeoutInSeconds * 1000000 + let _mtu = fromIntegral - config ^. mtu + (-8) -- 2 word32be + _timeout = fromIntegral - config ^. timeoutInSeconds * 1000000 let _localHost = config ^. localHost . re packed _localPort = show - config ^. localPort @@ -78,9 +122,11 @@ _remoteHost = config ^. remoteHost . re packed _remotePort = show - config ^. remotePort - _fromSocket = fromSocketTimeout timeout - _toSocket = toSocketTimeout timeout + _fromSocket = fromSocketTimeout _timeout + _toSocket = toSocketTimeout _timeout + _debug = config ^. debug + localThread <- pure - runSafeT . runEffect - serve (Host _localHost) _localPort - \(localSock, localSockAddr) -> do log - "local accepted: " <> view packed (show localSockAddr) @@ -91,14 +137,14 @@ liftIO - NS.setSocketOption remoteSock NS.NoDelay 1 let - localPull = _fromSocket localSock mtu + localPull = _fromSocket localSock _mtu - remotePull = _fromSocket remoteSock mtu + remotePull = _fromSocket remoteSock _mtu remotePush = _toSocket remoteSock sendThread <- liftIO - async - runEffect - do - localPull >-> obfsEncode (config ^. bound) (config ^. randomness) + localPull >-> obfsEncode _debug (config ^. randomnessInBytes) >-> remotePush liftIO - NS.shutdown remoteSock NS.ShutdownSend @@ -123,17 +169,17 @@ liftIO - NS.setSocketOption forwardSock NS.NoDelay 1 let - remotePull = _fromSocket remoteSock mtu + remotePull = _fromSocket remoteSock _mtu remotePush = _toSocket remoteSock - forwardPull = _fromSocket forwardSock mtu + forwardPull = _fromSocket forwardSock _mtu sendThread <- liftIO - async - do obfsDecode remotePull - send forwardSock liftIO - NS.shutdown forwardSock NS.ShutdownSend recvThread <- liftIO - async - runEffect - do - forwardPull >-> obfsEncode (config ^. bound) (config ^. randomness) + forwardPull >-> obfsEncode _debug (config ^. randomnessInBytes) >-> remotePush liftIO - NS.shutdown remoteSock NS.ShutdownSend @@ -143,11 +189,12 @@ case config ^. role of - Local -> do - _ <- localThread - pure () - Remote -> do - _ <- remoteThread + Local -> join localThread + Remote -> join remoteThread + Both -> do + local <- async - join localThread + remote <- async - join remoteThread + waitEitherCancel local remote pure () pure () diff --git a/src/Options.hs b/src/Options.hs --- a/src/Options.hs +++ b/src/Options.hs @@ -1,6 +1,5 @@ --- | - {-# LANGUAGE DeriveGeneric #-} +{-# LANGUAGE OverloadedStrings #-} module Options where @@ -11,16 +10,17 @@ data TunnelOptions = TunnelOptions { - localHost :: Maybe Text + role :: Maybe Text + , localHost :: Maybe Text , localPort :: Maybe Integer , remoteHost :: Text , remotePort :: Integer , forwardHost :: Maybe Text , forwardPort :: Maybe Integer - , remote :: Bool - , bound :: Maybe Integer - , randomness :: Maybe Integer + , randomnessInBytes :: Maybe Integer , timeoutInSeconds :: Maybe Integer + , mtu :: Maybe Integer + , debug :: Bool } deriving (Generic, Show, Eq) @@ -30,6 +30,12 @@ toConfig :: TunnelOptions -> Config toConfig o = let c = defaultConfig + _role = + case role o of + Just "remote" -> Remote + Just "local" -> Local + Just "both" -> Both + _ -> Local in Config { @@ -39,8 +45,9 @@ , _remotePort = remotePort o , _forwardHost = fromMaybe (_forwardHost c) (forwardHost o) , _forwardPort = fromMaybe (_forwardPort c) (forwardPort o) - , _role = if remote o then Remote else Local - , _bound = fromMaybe (_bound c) (bound o) - , _randomness = fromMaybe (_randomness c) (randomness o) + , _role = _role + , _randomnessInBytes = fromMaybe (_randomnessInBytes c) (randomnessInBytes o) , _timeoutInSeconds = fromMaybe (_timeoutInSeconds c) (timeoutInSeconds o) + , _mtu = fromMaybe (_mtu c) (mtu o) + , _debug = debug o } diff --git a/src/Type.hs b/src/Type.hs --- a/src/Type.hs +++ b/src/Type.hs @@ -7,7 +7,7 @@ import Control.Lens import Data.Text (Text) -data Role = Local | Remote +data Role = Local | Remote | Both deriving (Show, Eq) data Config = Config @@ -19,9 +19,10 @@ , _forwardHost :: Text , _forwardPort :: Integer , _role :: Role - , _bound :: Integer - , _randomness :: Integer + , _randomnessInBytes :: Integer , _timeoutInSeconds :: Integer + , _debug :: Bool + , _mtu :: Integer } deriving (Show, Eq) @@ -37,7 +38,8 @@ , _forwardHost = "127.0.0.1" , _forwardPort = 1080 , _role = Local - , _bound = 1024 - , _randomness = 300 + , _randomnessInBytes = 256 , _timeoutInSeconds = 3600 + , _debug = False + , _mtu = 4096 }