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|
-- | This module implements Scuttlebutt's Secret Handshake.
--
-- For more information kindly refer the to protocol guide
-- https://ssbc.github.io/scuttlebutt-protocol-guide
-- | TODO: Take care of possible import loop
-- | TODO: Optimize handling of PublicKey (extractPublicKey)
module Ssb.Peer.SecretHandshake where
import Protolude hiding ( Identity )
import qualified Data.ByteString as BS
import Data.Default
import qualified Crypto.Hash.SHA256 as SHA256
import qualified Crypto.Saltine.Core.ScalarMult
as ScalarMult
import qualified Crypto.Saltine.Class as Nacl
import qualified Crypto.Saltine.Core.Auth as Auth
import qualified Crypto.Saltine.Core.Box as Box
import qualified Crypto.Saltine.Core.SecretBox as SecretBox
import qualified Crypto.Saltine.Core.Sign as Sign
import Ssb.Network
import Ssb.Identity
import qualified Sodium
-- | ChallengeLength is the length of a challenge message in bytes
challengeLength :: Int
challengeLength = 64
-- | ClientAuthLength is the length of a clientAuth message in bytes
clientAuthLength :: Int
clientAuthLength = 16 + 32 + 64
-- | ServerAcceptLength is the length of a serverAccept message in bytes
serverAcceptLength :: Int
serverAcceptLength = 16 + 64
-- | MACLength is the length of a MAC in bytes
macLength :: Int
macLength = 16
-- | NetworkIdentifier defines which of the possible networks is being used.
-- Most traffic is on MainNet, and others may be used for testing purposes.
type NetworkIdentifier = ByteString
type SharedSecret = ScalarMult.GroupElement
-- | SharedSecrets are the result of Scuttlebutt's handshake
-- TODO: make shared secrets readable and showable
data SharedSecrets = SharedSecrets
{ network :: NetworkIdentifier
, secreta :: Maybe PublicKey
, secretA :: Maybe PublicKey
, secretb :: Maybe PublicKey
, secretB :: Maybe PublicKey
, secretab :: SharedSecret
, secretaB :: SharedSecret
, secretAb :: SharedSecret
, serverHMAC :: Auth.Authenticator
}
-- | ConnStatus defines the progress of the handshake.
data ConnStatus =
StartingHandshake
| AwaitingClientHello
| AwaitingServerHello
| AwaitingClientAuthentication
| AwaitingServerAccept
| HandshakeComplete
deriving Show
-- | Message sent between Scuttlebutt peers.
-- TODO: Add encoding and processing of remaining messages
data Message =
ClientHello Auth.Authenticator -- | Client's HMAC
PublicKey -- | Client's Ephemeral Public Key
NetworkIdentifier
| ServerHello Auth.Authenticator -- | Server's HMAC
PublicKey -- | Server's Ephemeral Public Key
NetworkIdentifier
-- TODO: Can this be renamed?
| ClientAuthMessage ByteString -- | Detached Signature A
PublicKey -- | Client long term Public Key
| ServerAccept ByteString -- | Detached Signature B
-- | ConnState holds important details during the connection process.
--
-- TODO: define a getter method for fields. Is it possible to get the field
-- name for the error message?
data ConnState = ConnState
{ connState :: ConnStatus
, networkID :: NetworkIdentifier
, clientPrivateKey :: Maybe PrivateKey
, clientPublicKey :: Maybe PublicKey
, clientEphemeralPrivKey :: Maybe PrivateKey
, clientEphemeralPubKey :: Maybe PublicKey
, clientHMAC :: Maybe Auth.Authenticator
, serverPrivateKey :: Maybe PrivateKey
, serverPublicKey :: Maybe PublicKey
, serverEphemeralPrivKey :: Maybe PrivateKey
, serverEphemeralPubKey :: Maybe PublicKey
, serverHMAC :: Maybe Auth.Authenticator
, sharedSecretab :: Maybe SharedSecret
, sharedSecretaB :: Maybe SharedSecret
, sharedSecretAb :: Maybe SharedSecret
, detachedSignatureA :: Maybe ByteString
, detachedSignatureB :: Maybe ByteString
}
-- | TODO: confirm use of default
instance Default ConnState where
def = ConnState { connState = StartingHandshake
, networkID = ""
, clientPrivateKey = def
, clientPublicKey = def
, clientEphemeralPrivKey = def
, clientEphemeralPubKey = def
, clientHMAC = def
, serverPrivateKey = def
, serverPublicKey = def
, serverEphemeralPrivKey = def
, serverEphemeralPubKey = def
, serverHMAC = def
, sharedSecretab = def
, sharedSecretaB = def
, sharedSecretAb = def
, detachedSignatureA = def
, detachedSignatureB = def
}
must :: Text -> Maybe a -> Either Text a
must field = maybeToEither ("missing " <> field)
-- | Create the state for initiating a Handshake given the Scuttlebutt User's key pair.
newClientConnState
:: NetworkIdentifier
-> Identity
-> PublicKey
-> IO ConnState
newClientConnState network clientID serverPubKey = do
let clientPrivKey = Ssb.Identity.privateKey clientID
let clientPubKey = Ssb.Identity.publicKey clientID
(ephPrivKey, ephPubKey) <- Box.newKeypair
return $ def { connState = StartingHandshake
, networkID = network
, clientPrivateKey = clientPrivKey
, clientPublicKey = Just clientPubKey
, clientEphemeralPrivKey = Just $ PrivateKey (Nacl.encode ephPrivKey)
, clientEphemeralPubKey = Just $ PublicKey (Nacl.encode ephPubKey)
, serverPublicKey = Just serverPubKey
}
-- | Create the state for initiating a Handshake given the Scuttlebutt User's key pair.
newServerConnState
:: NetworkIdentifier
-> Identity
-> IO ConnState
newServerConnState network serverID = do
let serverPrivKey = Ssb.Identity.privateKey serverID
let serverPubKey = Ssb.Identity.publicKey serverID
(ephPrivKey, ephPubKey) <- Box.newKeypair
return $ def { connState = AwaitingClientHello
, networkID = network
, serverEphemeralPrivKey = Just $ PrivateKey (Nacl.encode ephPrivKey)
, serverEphemeralPubKey = Just $ PublicKey (Nacl.encode ephPubKey)
, serverPrivateKey = serverPrivKey
, serverPublicKey = Just serverPubKey
}
-- | Create shared secrets given the Handshake's final connection state.
newSharedSecrets :: ConnState -> Either Text SharedSecrets
newSharedSecrets state = do
ssab <- must "secret key ab" $ sharedSecretab state
ssaB <- must "secret key aB" $ sharedSecretaB state
ssAb <- must "secret key Ab" $ sharedSecretAb state
serverHMAC' <- must "secret HMAC" $ serverHMAC (state :: ConnState)
return $ SharedSecrets { network = networkID state
, secreta = clientEphemeralPubKey state
, secretA = clientPublicKey state
, secretb = serverEphemeralPubKey state
, secretB = serverPublicKey state
, secretab = ssab
, secretaB = ssaB
, secretAb = ssAb
, serverHMAC = serverHMAC'
}
newClientAuthMessage :: ConnState -> Either Text Message
newClientAuthMessage state = do
let network = networkID state
cliLTPrivKey <- must "client Private Key" $ clientPrivateKey state
cliLTPubKey <- must "client Public Key" $ clientPublicKey state
srvLTPubKey <- must "server Public Key" $ serverPublicKey state
cliEphPrivKey <- must "client Private Key" $ clientEphemeralPrivKey state
srvEphPubKey <- must "server Ephemeral Public Key"
$ serverEphemeralPubKey state
ssab <- must "shared secret ab" $ sharedSecretab state
detachedSignatureA <- newDetachedSignatureA network
srvLTPubKey
ssab
cliLTPrivKey
return $ ClientAuthMessage detachedSignatureA
cliLTPubKey
newClientHello :: ConnState -> Either Text Message
newClientHello state = do
cliEphPubKey <- maybeToEither noKeyMsg $ clientEphemeralPubKey state
key <- maybeToEither badNetMsg $ Nacl.decode (networkID state)
let auth = Auth.auth key (extractPublicKey cliEphPubKey)
return $ ClientHello auth cliEphPubKey (networkID state)
where
badNetMsg = "badly formatted Network Identifier"
noKeyMsg = "clientEphemeralKey required"
decodeClientHello :: ConnState -> ByteString -> Either Text Message
decodeClientHello state buf = do
let network = networkID state
let (hmacbuf, cliEphPubKey) = BS.splitAt 32 buf
key <- maybeToEither badNetMsg $ Nacl.decode network
auth <- maybeToEither badHMACMsg $ Nacl.decode hmacbuf
let msg = cliEphPubKey
if Auth.verify key auth msg
then Right $ ClientHello auth (PublicKey cliEphPubKey) network
else Left badVerificationMsg
where
badNetMsg = "badly formatted Network Identifier"
badHMACMsg = "badly formatted server HMAC"
badPubKeyMsg = "badly formatted server Public Key"
badVerificationMsg = "verification failed"
-- TODO: check if its possible to change the function depending on the return type.
newServerHello :: ConnState -> Either Text Message
newServerHello state = do
srvEphPubKey <- maybeToEither noKeyMsg $ serverEphemeralPubKey state
key <- maybeToEither badNetMsg $ Nacl.decode (networkID state)
let auth = Auth.auth key (extractPublicKey srvEphPubKey)
return $ ServerHello auth srvEphPubKey (networkID state)
where
badNetMsg = "badly formatted Network Identifier"
noKeyMsg = "clientEphemeralKey required"
decodeServerHello :: ConnState -> ByteString -> Either Text Message
decodeServerHello state buf = do
let network = networkID state
let (hmacbuf, srvEphPubKey) = BS.splitAt 32 buf
key <- maybeToEither badNetMsg $ Nacl.decode network
auth <- maybeToEither badHMACMsg $ Nacl.decode hmacbuf
let msg = srvEphPubKey
if Auth.verify key auth msg
then Right $ ServerHello auth (PublicKey srvEphPubKey) network
else Left badVerificationMsg
where
badNetMsg = "badly formatted Network Identifier"
badHMACMsg = "badly formatted server HMAC"
badPubKeyMsg = "badly formatted server Public Key"
badVerificationMsg = "verification failed"
decodeClientAuthMessage :: ConnState -> ByteString -> Either Text Message
decodeClientAuthMessage state buf = do
let network = networkID state
serverPublicKey <- must "serverPublicKey" $ serverPublicKey state
sharedSecretab <- must "sharedSecretab" $ sharedSecretab state
sharedSecretaB <- must "sharedSecretaB" $ sharedSecretaB state
key <-
naclDecode "key"
$ SHA256.hash
$ network
<> Nacl.encode sharedSecretab
<> Nacl.encode sharedSecretaB
let nonce = Nacl.zero
msg3 <- maybeToEither "could not open secret box"
$ SecretBox.secretboxOpen key nonce buf
-- TODO: Make the client auth message length a constant
msg3 <- if (BS.length msg3 == 96)
then (return msg3)
else (Left badMessageLength)
let detachedSignatureA = BS.take 64 msg3
clientLongTermPubKey <- naclDecode "client Long Term Public Key"
$ BS.drop 64 msg3
let msg =
(network :: ByteString)
<> (extractPublicKey serverPublicKey)
<> SHA256.hash (Nacl.encode sharedSecretab)
if Sign.signVerifyDetached
clientLongTermPubKey
detachedSignatureA
msg
then Right state {connState = HandshakeComplete}
else Left "client verification failed"
return $ ClientAuthMessage
detachedSignatureA
(PublicKey $ Nacl.encode clientLongTermPubKey)
where
badMessageLength = "unexpected length of Client Authentication Message"
naclDecode msg = maybeToEither msg . Nacl.decode
newServerAccept :: ConnState -> Either Text Message
newServerAccept state = do
detachedSignatureB' <- maybeToEither noSigB (detachedSignatureB state)
return $ ServerAccept detachedSignatureB'
where
noSigB = "detachedSignatureB required"
decodeServerAccept :: ConnState -> ByteString -> Either Text Message
decodeServerAccept state buf = do
let network = networkID state
sharedSecretab <- must "sharedSecretab" $ sharedSecretab state
sharedSecretaB <- must "sharedSecretaB" $ sharedSecretaB state
sharedSecretAb <- must "sharedSecretAb" $ sharedSecretAb state
key <-
naclDecode "key"
$ SHA256.hash
$ network
<> Nacl.encode sharedSecretab
<> Nacl.encode sharedSecretaB
<> Nacl.encode sharedSecretAb
let nonce = Nacl.zero
detachedSignatureB <- secretBoxOpen key nonce buf
return $ ServerAccept detachedSignatureB
where
naclDecode msg =
maybeToEither ("could not decode " <> msg :: Text) . Nacl.decode
secretBoxOpen key nonce msg =
maybeToEither "could not open secret box"
$ SecretBox.secretboxOpen key nonce msg
-- | generate a signature used in the Client Authentication
newDetachedSignatureA
:: NetworkIdentifier
-> Ssb.Identity.PublicKey
-> SharedSecret
-> PrivateKey
-> Either Text ByteString
newDetachedSignatureA network serverLongTermPubKey sharedSecretab clientLongTermPrivKey
= do
clientLongTermPrivKey' <- maybeToEither badCliKeyMsg
$ Nacl.decode $ extractPrivateKey clientLongTermPrivKey
let secretChecksum = SHA256.hash $ Nacl.encode sharedSecretab
let msg =
(network :: ByteString)
<> extractPublicKey serverLongTermPubKey
<> (secretChecksum :: ByteString)
return $ Sign.signDetached clientLongTermPrivKey' msg
where
badSrvKeyMsg = "badly encoded long term server public key"
badCliKeyMsg = "badly encoded long term client private key"
calcSharedSecretab :: PrivateKey -> PublicKey -> Either Text SharedSecret
calcSharedSecretab cliEphPrivKey srvEphPubKey = do
cliEphPrivKey' <- maybeToEither "badly formatted client ephemeral private key"
$ Nacl.decode $ extractPrivateKey cliEphPrivKey
srvEphPubKey' <- maybeToEither "badly formatted server ephemeral public key"
$ Nacl.decode $ extractPublicKey srvEphPubKey
return $ ScalarMult.mult cliEphPrivKey' srvEphPubKey'
-- | generate a signature used in the Server acknowledgement
newDetachedSignatureB
:: NetworkIdentifier
-> ByteString
-> PublicKey
-> SharedSecret
-> PrivateKey
-> Either Text ByteString
newDetachedSignatureB network detachedSignatureA clientPublicKey sharedSecretab serverPrivateKey = do
key <- naclDecode badPrivkey $ extractPrivateKey serverPrivateKey
let msg =
(network :: ByteString)
<> detachedSignatureA
<> (extractPublicKey clientPublicKey)
<> SHA256.hash (Nacl.encode sharedSecretab)
return $ Sign.signDetached key msg
where
badPrivkey = "badly formatted private key"
naclDecode msg = maybeToEither msg . Nacl.decode
-- | Server Longterm PK should be converted to curve25519
-- Does not look like a problem given the Golang code
-- TODO: Implement type conversion here
clientCalcSharedSecretaB :: PrivateKey -> PublicKey -> Either Text SharedSecret
clientCalcSharedSecretaB clientEphemeralSK serverLongtermPK = do
cliEphPrivKey' <- maybeToEither "badly formatted client ephemeral private key"
$ Nacl.decode $ extractPrivateKey clientEphemeralSK
srvLTPubKey' <- maybeToEither "badly formatted server long term public key"
$ Nacl.decode $ extractPublicKey serverLongtermPK
curvePublicKey <-
maybeToEither "badly formatted curve25519"
$ Nacl.decode . Nacl.encode $ Sodium.publicKeyToCurve25519 srvLTPubKey'
return $ ScalarMult.mult cliEphPrivKey' curvePublicKey
serverCalcSharedSecretaB :: PrivateKey -> PublicKey -> Either Text SharedSecret
serverCalcSharedSecretaB serverLongtermSK clientEphemeralPK = do
srvLTPrivKey' <- maybeToEither "badly formatted server long term private key"
$ Nacl.decode $ extractPrivateKey serverLongtermSK
cliEphPubKey' <- maybeToEither "badly formatted client ephemeral public key"
$ Nacl.decode $ extractPublicKey clientEphemeralPK
curvePrivKey <-
maybeToEither "badly formatted curve25519"
$ Nacl.decode . Nacl.encode $ Sodium.secretKeyToCurve25519 srvLTPrivKey'
return $ ScalarMult.mult curvePrivKey cliEphPubKey'
calcSharedSecretAb :: PrivateKey -> PublicKey -> Either Text SharedSecret
calcSharedSecretAb clientLongTermPrivKey serverEphemeralPubKey = do
cliLTPrivKey' <- naclDecode "badly formatted client long term private key"
$ extractPrivateKey clientLongTermPrivKey
curveSecretKey <-
naclDecode "badly formatted curve25519"
. Nacl.encode
$ Sodium.secretKeyToCurve25519 cliLTPrivKey'
srvEphPubKey' <- naclDecode "badly formatted server ephemeral public key"
$ extractPublicKey serverEphemeralPubKey
return $ ScalarMult.mult curveSecretKey srvEphPubKey'
where naclDecode msg = maybeToEither msg . Nacl.decode
serverCalcSharedSecretAb
:: PrivateKey
-> PublicKey
-> Either Text SharedSecret
serverCalcSharedSecretAb serverEphemeralPrivKey clientLongTermPubKey = do
srvEphPrivKey' <- naclDecode "here bad formatted server long term private key"
$ extractPrivateKey serverEphemeralPrivKey
cliLTPubKey' <- naclDecode "badly formatted client long term public key"
$ extractPublicKey clientLongTermPubKey
curvePublicKey <-
naclDecode "badly formatted curve25519"
. Nacl.encode
$ Sodium.publicKeyToCurve25519 cliLTPubKey'
return $ ScalarMult.mult srvEphPrivKey' curvePublicKey
where
naclDecode msg = maybeToEither msg . Nacl.decode
-- | encode and serialize the message in preparation to send to peer.
encode :: ConnState -> Message -> Either Text ByteString
encode state msg = case msg of
ClientHello auth pubKey network -> do
cliEphPubKey <- maybeToEither noKeyMsg $ clientEphemeralPubKey state
return $ Nacl.encode auth <> extractPublicKey cliEphPubKey
where
noKeyMsg = "clientEphemeralKey required"
ServerHello auth pubKey network -> do
return $ Nacl.encode auth <> extractPublicKey pubKey
where
noKeyMsg = "clientEphemeralKey required"
ClientAuthMessage dSigA cliLTPubKey -> do
let network = networkID state
ssab <- must "shared secret ab" $ sharedSecretab state
ssaB <- must "shared secret aB" $ sharedSecretaB state
key <-
maybeToEither badKeyMsg
$ Nacl.decode
$ SHA256.hash
$ network
<> Nacl.encode ssab
<> Nacl.encode ssaB
let nonce = Nacl.zero
let msg = dSigA <> extractPublicKey cliLTPubKey
return $ SecretBox.secretbox key nonce msg
where badKeyMsg = "clientEphemeralKey required"
ServerAccept detachedSignatureB -> do
let network = networkID state
ssab <- must "shared secret ab" $ sharedSecretab state
ssaB <- must "shared secret aB" $ sharedSecretaB state
ssAb <- must "shared secret Ab" $ sharedSecretAb state
key <-
maybeToEither badKeyMsg
$ Nacl.decode
$ SHA256.hash
$ ((network :: ByteString)
<> Nacl.encode ssab
<> Nacl.encode ssaB
<> Nacl.encode ssAb)
let nonce = Nacl.zero
let msg = detachedSignatureB
return $ SecretBox.secretbox key nonce msg
where badKeyMsg = "clientEphemeralKey required"
-- | update the connection state and return any reponse message for the peer.
-- TODO: Process secretAb
process :: ConnState -> Message -> IO (Either Text (ConnState, Maybe Message))
process state (ClientHello hmac cliEphPubKey network) = do
stateUpdate <- return $ do
srvLTPrivKey <- must "server Private Key"
$ serverPrivateKey state
srvEphPrivKey <- must "server ephemeral Private Key"
$ serverEphemeralPrivKey state
ssab <- calcSharedSecretab srvEphPrivKey cliEphPubKey
-- TODO: srvLTPubKey should be curved Process sk_to_curve25519
ssaB <- serverCalcSharedSecretaB srvLTPrivKey cliEphPubKey
return $ state { connState = AwaitingClientAuthentication
, clientEphemeralPubKey = Just cliEphPubKey
, serverHMAC = Just hmac
, sharedSecretab = Just ssab
, sharedSecretaB = Just ssaB
}
return $ stateUpdate >>= \state' -> case newServerHello state' of
Right msg' -> return $ (state', Just msg')
Left err -> Left err
process state (ServerHello hmac ephPubKey network) = do
stateUpdate <- return $ do
cliLTPrivKey <- must "client Private Key" $ clientPrivateKey state
cliEphPrivKey <- must "ephemeral client Private Key"
$ clientEphemeralPrivKey state
srvLTPubKey <- must "server Public Key" $ serverPublicKey state
ssab <- calcSharedSecretab cliEphPrivKey ephPubKey
ssaB <- clientCalcSharedSecretaB cliEphPrivKey srvLTPubKey
ssAb <- calcSharedSecretAb cliLTPrivKey ephPubKey
return $ state { connState = AwaitingServerAccept
, serverHMAC = Just hmac
, serverEphemeralPubKey = Just ephPubKey
, sharedSecretab = Just ssab
, sharedSecretaB = Just ssaB
, sharedSecretAb = Just ssAb
}
return $ stateUpdate >>= \state' -> case newClientAuthMessage state' of
Right msg' -> return $ (state', Just msg')
Left err -> Left err
process state (ClientAuthMessage detachedSignatureA clientLongTermPubKey) = do
stateUpdate <- return $ do
let network = networkID state
srvPrivKey <- must "server private key"
$ serverPrivateKey state
srvEphPrivKey <- must "server Long Term ephemeral private key"
$ serverEphemeralPrivKey state
sharedSecretAb <- serverCalcSharedSecretAb srvEphPrivKey clientLongTermPubKey
sharedSecretab <- must "shared secret ab" $ sharedSecretab state
detachedSignatureB <- newDetachedSignatureB
network
detachedSignatureA
clientLongTermPubKey
sharedSecretab
srvPrivKey
return $ state { connState = HandshakeComplete
, detachedSignatureA = Just detachedSignatureA
, detachedSignatureB = Just detachedSignatureB
, clientPublicKey = Just clientLongTermPubKey
, sharedSecretAb = Just sharedSecretAb
}
return $ stateUpdate >>= \state' -> case newServerAccept state' of
Right msg' -> return $ (state', Just msg')
Left err -> Left err
process state (ServerAccept dSigB) = do
stateUpdate <- return $ do
let network = networkID state
cliLTPrivKey <- must "client private key" $ clientPrivateKey state
cliLTPubKey <- must "client public key" $ clientPublicKey state
srvLTPubKey <- must "server public key" $ serverPublicKey state
ssab <- must "shared secret ab" $ sharedSecretab state
detachedSignatureA <- newDetachedSignatureA network
srvLTPubKey
ssab
cliLTPrivKey
keyBuf <- must "server Public Key" $ serverPublicKey state
key <- maybeToEither "badly formatted public key" $ Nacl.decode $ extractPublicKey keyBuf
let msg = network <> detachedSignatureA <> extractPublicKey cliLTPubKey <> SHA256.hash (Nacl.encode ssab)
if Sign.signVerifyDetached key dSigB msg
then Right state {connState = HandshakeComplete}
else Left "server verification failed"
return $ case stateUpdate of
Right state' -> return (state', Nothing)
Left err -> Left err
-- TODO: Investigate a better way to separate network from handshake logic
type ReadFn = Int -> IO (Maybe ByteString)
type SendFn = ByteString -> IO ()
-- | readMsg decodes the next expected message from the byte stream.
readMsg :: ConnState -> ReadFn -> IO (Either Text Message)
readMsg state read = case connState state of
AwaitingClientHello -> do
mbuf <- read' challengeLength
return $ do
buf <- mbuf
decodeClientHello state buf
AwaitingServerHello -> do
mbuf <- read' challengeLength
return $ do
buf <- mbuf
decodeServerHello state buf
AwaitingClientAuthentication -> do
mbuf <- read' 112
return $ do
buf <- mbuf
decodeClientAuthMessage state buf
AwaitingServerAccept -> do
mbuf <- read' serverAcceptLength
return $ do
buf <- mbuf
decodeServerAccept state buf
_ -> return $ Left "unknown state"
where read' len = maybeToEither "connection broken" <$> read len
-- TODO: use Either instead
sendMsg :: SendFn -> ConnState -> Message -> IO ()
sendMsg send state msg = do
case encode state msg of
Left err -> die err
Right buf -> send buf
-- | startHandshake initializes the connection with the Scuttlebutt peer
-- returning the new shared secrets upon completion.
startHandshake
:: SendFn
-> ReadFn
-> NetworkIdentifier
-> Identity
-> PublicKey
-> IO (Either Text SharedSecrets)
startHandshake send recv network clientID srvPubKey = do
state <- newClientConnState network clientID srvPubKey
let clientHello = fromRight undefined (newClientHello state)
let state' = state { connState = AwaitingServerHello }
finalState <- loop state' recv (Just clientHello)
return $ finalState >>= newSharedSecrets
where
loop :: ConnState -> ReadFn -> Maybe Message -> IO (Either Text ConnState)
loop state _ Nothing = return . return $ state
loop state recv (Just msg) = do
sendMsg send state msg
case connState state of
HandshakeComplete -> return . return $ state
_ -> do
resp <- readMsg state recv
case resp of
Left err -> return $ Left err
Right msg -> do
res <- process state msg
case res of
Left err -> return $ Left ("handshake error while connecting to peer: " <> err)
Right (state', msg') ->
loop state' recv msg'
welcomeHandshake
:: SendFn
-> ReadFn
-> NetworkIdentifier
-> Identity
-> IO (Either Text SharedSecrets)
welcomeHandshake send recv network serverID = do
state <- newServerConnState network serverID
finalState <- loop state
return $ finalState >>= newSharedSecrets
where
loop :: ConnState -> IO (Either Text ConnState)
loop state = do
msg <- readMsg state recv
case msg of
Left err -> return $ Left err
Right msg -> do
res <- process state msg
case res of
Left err -> return $ Left $ "handshake failed: " <> err
Right (state', msg') ->
case msg' of
Nothing -> return $ Right state'
Just msg'' -> do
sendMsg send state' msg''
case connState state' of
HandshakeComplete -> return $ Right state'
_ -> loop state'
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