189 lines
6.6 KiB
Haskell
189 lines
6.6 KiB
Haskell
-- |
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-- Module : Network.TLS.Sending
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-- License : BSD-style
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-- Maintainer : Vincent Hanquez <vincent@snarc.org>
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-- Stability : experimental
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-- Portability : unknown
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--
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-- the Sending module contains calls related to marshalling packets according
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-- to the TLS state
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--
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module Network.TLS.Sending (
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writePacket
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) where
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import Control.Monad.State
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import Data.ByteString (ByteString)
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import qualified Data.ByteString as B
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import Network.TLS.Util
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import Network.TLS.Cap
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import Network.TLS.Wire
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import Network.TLS.Struct
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import Network.TLS.Packet
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import Network.TLS.State
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import Network.TLS.Cipher
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import Network.TLS.Crypto
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{-
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- 'makePacketData' create a Header and a content bytestring related to a packet
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- this doesn't change any state
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-}
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makePacketData :: Packet -> TLSSt (Header, ByteString)
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makePacketData pkt = do
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ver <- get >>= return . stVersion
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content <- writePacketContent pkt
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let hdr = Header (packetType pkt) ver (fromIntegral $ B.length content)
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return (hdr, content)
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{-
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- Handshake data need to update a digest
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-}
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processPacketData :: (Header, ByteString) -> TLSSt (Header, ByteString)
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processPacketData dat@(Header ty _ _, content) = do
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when (ty == ProtocolType_Handshake) (updateHandshakeDigest content)
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return dat
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{-
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- when Tx Encrypted is set, we pass the data through encryptContent, otherwise
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- we just return the packet
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-}
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encryptPacketData :: (Header, ByteString) -> TLSSt (Header, ByteString)
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encryptPacketData dat = do
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st <- get
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if stTxEncrypted st
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then encryptContent dat
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else return dat
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{-
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- ChangeCipherSpec state change need to be handled after encryption otherwise
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- its own packet would be encrypted with the new context, instead of beeing sent
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- under the current context
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-}
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postprocessPacketData :: (Header, ByteString) -> TLSSt (Header, ByteString)
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postprocessPacketData dat@(Header ProtocolType_ChangeCipherSpec _ _, _) =
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switchTxEncryption >> isClientContext >>= \cc -> when cc setKeyBlock >> return dat
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postprocessPacketData dat = return dat
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{-
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- marshall packet data
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-}
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encodePacket :: (Header, ByteString) -> TLSSt ByteString
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encodePacket (hdr, content) = return $ B.concat [ encodeHeader hdr, content ]
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{-
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- just update TLS state machine
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-}
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preProcessPacket :: Packet -> TLSSt ()
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preProcessPacket (Alert _) = return ()
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preProcessPacket (AppData _) = return ()
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preProcessPacket (ChangeCipherSpec) = updateStatusCC True >> return () -- FIXME don't ignore this error just in case
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preProcessPacket (Handshake hss) = forM_ hss $ \hs -> do
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-- FIXME don't ignore this error
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_ <- updateStatusHs (typeOfHandshake hs)
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case hs of
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Finished fdata -> updateVerifiedData True fdata
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_ -> return ()
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{-
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- writePacket transform a packet into marshalled data related to current state
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- and updating state on the go
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-}
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writePacket :: Packet -> TLSSt ByteString
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writePacket pkt = preProcessPacket pkt >> makePacketData pkt >>= processPacketData >>=
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encryptPacketData >>= postprocessPacketData >>= encodePacket
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{------------------------------------------------------------------------------}
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{- SENDING Helpers -}
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{------------------------------------------------------------------------------}
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{- if the RSA encryption fails we just return an empty bytestring, and let the protocol
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- fail by itself; however it would be probably better to just report it since it's an internal problem.
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-}
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encryptRSA :: ByteString -> TLSSt ByteString
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encryptRSA content = do
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st <- get
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let rsakey = fromJust "rsa public key" $ hstRSAPublicKey $ fromJust "handshake" $ stHandshake st
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case withTLSRNG (stRandomGen st) (\g -> kxEncrypt g rsakey content) of
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Left err -> fail ("rsa encrypt failed: " ++ show err)
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Right (econtent, rng') -> put (st { stRandomGen = rng' }) >> return econtent
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encryptContent :: (Header, ByteString) -> TLSSt (Header, ByteString)
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encryptContent (hdr@(Header pt ver _), content) = do
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digest <- makeDigest True hdr content
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encrypted_msg <- encryptData $ B.concat [content, digest]
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let hdrnew = Header pt ver (fromIntegral $ B.length encrypted_msg)
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return (hdrnew, encrypted_msg)
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encryptData :: ByteString -> TLSSt ByteString
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encryptData content = do
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st <- get
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let cipher = fromJust "cipher" $ stCipher st
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let cst = fromJust "tx crypt state" $ stTxCryptState st
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let padding_size = fromIntegral $ cipherPaddingSize cipher
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let msg_len = B.length content
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let padding = if padding_size > 0
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then
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let padbyte = padding_size - (msg_len `mod` padding_size) in
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let padbyte' = if padbyte == 0 then padding_size else padbyte in
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B.replicate padbyte' (fromIntegral (padbyte' - 1))
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else
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B.empty
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let writekey = cstKey cst
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case cipherF cipher of
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CipherNoneF -> return content
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CipherBlockF encrypt _ -> do
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-- before TLS 1.1, the block cipher IV is made of the residual of the previous block.
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iv <- if hasExplicitBlockIV $ stVersion st
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then genTLSRandom (fromIntegral $ cipherIVSize cipher)
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else return $ cstIV cst
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let e = encrypt writekey iv (B.concat [ content, padding ])
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if hasExplicitBlockIV $ stVersion st
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then return $ B.concat [iv,e]
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else do
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let newiv = fromJust "new iv" $ takelast (fromIntegral $ cipherIVSize cipher) e
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put $ st { stTxCryptState = Just $ cst { cstIV = newiv } }
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return e
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CipherStreamF initF encryptF _ -> do
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let iv = cstIV cst
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let (e, newiv) = encryptF (if iv /= B.empty then iv else initF writekey) content
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put $ st { stTxCryptState = Just $ cst { cstIV = newiv } }
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return e
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writePacketContent :: Packet -> TLSSt ByteString
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writePacketContent (Handshake hss) = return . B.concat =<< mapM makeContent hss where
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makeContent hs@(ClientKeyXchg _ _) = do
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ver <- get >>= return . stVersion
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let premastersecret = runPut $ encodeHandshakeContent hs
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setMasterSecret premastersecret
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econtent <- encryptRSA premastersecret
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let extralength =
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if ver < TLS10
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then B.empty
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else runPut $ putWord16 $ fromIntegral $ B.length econtent
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let hdr = runPut $ encodeHandshakeHeader (typeOfHandshake hs)
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(fromIntegral (B.length econtent + B.length extralength))
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return $ B.concat [hdr, extralength, econtent]
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makeContent hs@(ClientHello ver crand _ _ _ _) = do
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cc <- isClientContext
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when cc (startHandshakeClient ver crand)
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return $ encodeHandshakes [hs]
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makeContent hs@(ServerHello ver srand _ _ _ _) = do
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cc <- isClientContext
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unless cc $ do
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setVersion ver
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setServerRandom srand
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return $ encodeHandshakes [hs]
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makeContent hs = return $ encodeHandshakes [hs]
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writePacketContent (Alert a) = return $ encodeAlerts a
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writePacketContent (ChangeCipherSpec) = return $ encodeChangeCipherSpec
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writePacketContent (AppData x) = return x
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