{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
-- | This module exports simple tools for establishing TLS-secured TCP
-- connections, relevant to both the client side and server side of the
-- connection.
--
-- This module re-exports some functions from the "Network.Simple.TCP" module
-- in the @network-simple@ package. Consider using that module directly if you
-- need a similar API without TLS support.
--
-- This module uses 'MonadIO' and 'C.MonadMask' extensively so that you can
-- reuse these functions in monads other than 'IO'. However, if you don't care
-- about any of that, just pretend you are using the 'IO' monad all the time
-- and everything will work as expected.
module Network.Simple.TCP.TLS (
-- * Server side
serve
-- ** Listening
, S.listen
-- ** Accepting
, accept
, acceptFork
-- ** Server TLS Settings
, ServerSettings
, makeServerSettings
, updateServerParams
, serverParams
-- * Client side
, connect
-- ** Client TLS Settings
, ClientSettings
, makeClientSettings
, getDefaultClientSettings
, updateClientParams
, clientParams
-- * Utils
, recv
, send
-- * Low level support
, useTls
, useTlsThenClose
, useTlsThenCloseFork
, connectTls
, acceptTls
, makeClientContext
, makeServerContext
-- * Note to Windows users
, NS.withSocketsDo
-- * Re-exports
-- $reexports
, module Network.Simple.TCP
, module Network.Socket
, module Network.TLS
, T.Credentials
) where
import Control.Concurrent (ThreadId, forkFinally)
import qualified Control.Exception as E
import Control.Monad
import qualified Control.Monad.Catch as C
import Control.Monad.IO.Class (MonadIO, liftIO)
import qualified Data.ByteString as B
import qualified Data.ByteString.Lazy as BL
import Data.Default (def)
import Data.List (intersect)
import Data.Maybe (isJust, listToMaybe)
import qualified Data.X509 as X
import qualified Data.X509.CertificateStore as X
import qualified Data.X509.Validation as X
import Foreign.C.Error (Errno(Errno), ePIPE)
import qualified GHC.IO.Exception as Eg
import qualified Network.Simple.TCP as S
import Network.Simple.TCP (HostPreference(Host, HostAny, HostIPv4, HostIPv6))
import Network.Socket (HostName, ServiceName, Socket, SockAddr)
import qualified Network.Socket as NS
import qualified Network.Socket.ByteString as NSB
import qualified Network.TLS as T
import Network.TLS (Context)
import Network.TLS.Extra as TE
import System.X509 (getSystemCertificateStore)
--------------------------------------------------------------------------------
-- $reexports
--
-- For your convenience, this module module also re-exports the following types
-- from other modules:
--
-- [From "Network.Socket"] 'HostName', 'ServiceName', 'Socket', 'SockAddr'.
--
-- [From "Network.Simple.TCP"]
-- @'HostPreference'('Host','HostAny','HostIPv4','HostIPv6')@.
--
-- [From "Network.TLS"] 'Context'.
--------------------------------------------------------------------------------
-- Client side TLS settings
-- | Abstract type representing the configuration settings for a TLS client.
--
-- Use 'makeClientSettings' or 'getDefaultClientSettings' to obtain a
-- 'ClientSettings' value.
data ClientSettings = ClientSettings { unClientSettings :: T.ClientParams }
-- | Get the system default 'ClientSettings' for a particular 'X.ServiceID'.
--
-- Defaults: No client credentials, system certificate store.
--
-- See 'makeClientSettings' to better understand the default settings used.
getDefaultClientSettings :: MonadIO m => X.ServiceID -> m ClientSettings
getDefaultClientSettings sid = liftIO $ do
makeClientSettings sid (T.Credentials []) <$> getSystemCertificateStore
-- | Make defaults 'ClientSettings'.
--
-- Certificate chain validation is done by 'X.validateDefault' from the
-- "Data.X509.Validation" module.
--
-- The Server Name Indication (SNI) TLS extension is enabled.
--
-- The supported cipher suites are those enumerated by 'TE.ciphersuite_default',
-- in decreasing order of preference.
--
-- Secure renegotiation is enabled.
--
-- Only the __TLS 1.1__ and __TLS 1.2__ protocols are supported by default.
--
-- If you are unsatisfied with any of these settings, use 'updateClientParams'
-- to change them.
makeClientSettings
:: X.ServiceID
-- ^ @
-- 'X.ServiceID' ~ ('HostName', 'B.ByteString')
-- @
--
-- Identification of the connection consisting of the fully qualified host
-- name for the server (e.g. www.example.com) and an optional suffix.
--
-- It is important that the hostname part is properly filled for security
-- reasons, as it allow to properly associate the remote side with the given
-- certificate during a handshake.
--
-- The suffix is used to identity a certificate per service on a specific
-- host. For example, a same host might have different certificates on
-- differents ports (443 and 995). For TCP connections, it's recommended
-- to use: @:port@, or @:service@ for the blob (e.g., \@":443"@, @\":https"@).
-> T.Credentials
-- ^ Credentials to provide to the server if requested. Only credentials
-- matching the server's 'X.DistinguishedName' will be submitted.
--
-- Initial credentials can be loaded with 'T.credentialLoadX509'
-> X.CertificateStore
-- ^ CAs used to verify the server certificate.
--
-- Use 'getSystemCertificateStore' to obtain the operating system's defaults.
-> ClientSettings
makeClientSettings (hn, sp) (T.Credentials creds) cStore =
ClientSettings $ (T.defaultParamsClient hn sp)
{ T.clientUseServerNameIndication = True
, T.clientSupported = def
{ T.supportedVersions = [T.TLS12, T.TLS11]
, T.supportedCiphers = TE.ciphersuite_default
, T.supportedSecureRenegotiation = True
, T.supportedClientInitiatedRenegotiation = True }
, T.clientShared = def { T.sharedCAStore = cStore }
, T.clientHooks = def
{ T.onServerCertificate = X.validateDefault
, T.onCertificateRequest = pure . findCredential }
}
where
-- | Find the first Credential that matches the given requirements.
-- Currently, the only requirement considered is the subject DN.
findCredential
:: ([T.CertificateType],
Maybe [T.HashAndSignatureAlgorithm],
[X.DistinguishedName])
-> Maybe (X.CertificateChain, X.PrivKey)
findCredential (_, _, dns) = listToMaybe (filter isSubject creds)
where
isSubject (X.CertificateChain cc, _) =
any (\c -> (X.certSubjectDN . X.getCertificate) c `elem` dns) cc
-- | Update advanced TLS client configuration 'T.ClientParams'.
--
-- See the "Network.TLS" module for details.
updateClientParams
:: (T.ClientParams -> T.ClientParams) -> ClientSettings -> ClientSettings
updateClientParams f = ClientSettings . f . unClientSettings
-- | A 'Control.Lens.Lens' into the TLS client configuration 'T.ClientParams'.
--
-- See the "Network.TLS" and the @lens@ package for details.
clientParams
:: Functor f
=> (T.ClientParams -> f T.ClientParams)
-> (ClientSettings -> f ClientSettings)
clientParams f = fmap ClientSettings . f . unClientSettings
--------------------------------------------------------------------------------
-- Server side TLS settings
-- | Abstract type representing the configuration settings for a TLS server.
--
-- Use 'makeServerSettings' to construct a 'ServerSettings' value, and
-- 'updateServerParams' to update it.
data ServerSettings = ServerSettings { unServerSettings :: T.ServerParams }
-- | Make default 'ServerSettings'.
--
-- The supported cipher suites are those enumerated by 'TE.ciphersuite_strong',
-- in decreasing order of preference. The cipher suite preferred by the server
-- is used.
--
-- Secure renegotiation initiated by the server is enabled, but renegotiation
-- initiated by the client is disabled.
--
-- Only the __TLS 1.1__ and __TLS 1.2__ protocols are supported by default.
--
-- If you are unsatisfied with any of these settings, use 'updateServerParams'
-- to change them.
makeServerSettings
:: T.Credential
-- ^ Server credential.
-> Maybe X.CertificateStore
-- ^ CAs used to verify the client certificate.
--
-- If specified, then a valid client certificate will be expected during
-- handshake.
--
-- Use 'getSystemCertificateStore' to obtain the operating system's defaults.
-> ServerSettings
makeServerSettings cred ycStore =
ServerSettings $ def
{ T.serverWantClientCert = isJust ycStore
, T.serverShared = def
{ T.sharedCredentials = T.Credentials [cred] }
, T.serverCACertificates = []
, T.serverSupported = def
{ T.supportedVersions = [T.TLS12, T.TLS11]
, T.supportedCiphers = TE.ciphersuite_strong
, T.supportedSession = True
, T.supportedSecureRenegotiation = True
, T.supportedClientInitiatedRenegotiation = False }
, T.serverHooks = def
{ T.onClientCertificate = clientCertsCheck
, T.onCipherChoosing = chooseCipher }
}
where
clientCertsCheck :: X.CertificateChain -> IO T.CertificateUsage
clientCertsCheck certs = case ycStore of
Nothing -> return T.CertificateUsageAccept
Just cs -> do
let checks = X.defaultChecks { X.checkFQHN = False }
es <- X.validate X.HashSHA256 X.defaultHooks checks cs def ("","") certs
case es of
[] -> pure T.CertificateUsageAccept
errs' -> pure (T.CertificateUsageReject (T.CertificateRejectOther
("Unacceptable client cert: " ++ show errs')))
-- Ciphers prefered by the server take precedence.
chooseCipher :: T.Version -> [T.Cipher] -> T.Cipher
chooseCipher _ cCiphs = head (intersect TE.ciphersuite_strong cCiphs)
-- | Update advanced TLS server configuration 'T.Params'.
--
-- See the "Network.TLS" module for details.
updateServerParams
:: (T.ServerParams -> T.ServerParams) -> ServerSettings -> ServerSettings
updateServerParams f = ServerSettings . f . unServerSettings
-- | A 'Control.Lens.Lens' into the TLS server configuration 'T.Params'.
-- See the "Network.TLS" and the @lens@ package for details.
serverParams
:: Functor f
=> (T.ServerParams -> f T.ServerParams)
-> (ServerSettings -> f ServerSettings)
serverParams f = fmap ServerSettings . f . unServerSettings
--------------------------------------------------------------------------------
-- | Start a TLS-secured TCP server that accepts incoming connections and
-- handles each of them concurrently, in different threads.
--
-- Any acquired network resources are properly closed and discarded when done or
-- in case of exceptions. This function binds a listening socket, accepts an
-- incoming connection, performs a TLS handshake and then safely closes the
-- connection when done or in case of exceptions. You don't need to perform any
-- of those steps manually.
serve
:: MonadIO m
=> ServerSettings -- ^TLS settings.
-> S.HostPreference -- ^Preferred host to bind.
-> ServiceName -- ^Service port to bind.
-> ((Context, SockAddr) -> IO ())
-- ^Computation to run in a different thread
-- once an incomming connection is accepted and a
-- TLS-secured communication is established. Takes the
-- TLS connection context and remote end address.
-> m ()
serve ss hp port k = liftIO $ do
S.listen hp port $ \(lsock,_) -> do
forever $ acceptFork ss lsock k
--------------------------------------------------------------------------------
-- | Accepts a single incomming TLS-secured TCP connection and use it.
--
-- A TLS handshake is performed immediately after establishing the TCP
-- connection and the TLS and TCP connections are properly closed when done or
-- in case of exceptions. If you need to manage the lifetime of the connection
-- resources yourself, then use 'acceptTls' instead.
accept
:: (MonadIO m, C.MonadMask m)
=> ServerSettings -- ^TLS settings.
-> Socket -- ^Listening and bound socket.
-> ((Context, SockAddr) -> m r)
-- ^Computation to run in a different thread
-- once an incomming connection is accepted and a
-- TLS-secured communication is established. Takes the
-- TLS connection context and remote end address.
-> m r
accept ss lsock k = C.bracket (acceptTls ss lsock)
(liftIO . T.contextClose . fst)
(useTls k)
-- | Like 'accept', except it uses a different thread to performs the TLS
-- handshake and run the given computation.
acceptFork
:: MonadIO m
=> ServerSettings -- ^TLS settings.
-> Socket -- ^Listening and bound socket.
-> ((Context, SockAddr) -> IO ())
-- ^Computation to run in a different thread
-- once an incomming connection is accepted and a
-- TLS-secured communication is established. Takes the
-- TLS connection context and remote end address.
-> m ThreadId
acceptFork ss lsock k = liftIO $ do
E.bracketOnError (acceptTls ss lsock)
(T.contextClose . fst)
(useTlsThenCloseFork k)
--------------------------------------------------------------------------------
-- | Connect to a TLS-secured TCP server and use the connection
--
-- A TLS handshake is performed immediately after establishing the TCP
-- connection and the TLS and TCP connections are properly closed when done or
-- in case of exceptions. If you need to manage the lifetime of the connection
-- resources yourself, then use 'connectTls' instead.
connect
:: (MonadIO m, C.MonadMask m)
=> ClientSettings -- ^TLS settings.
-> HostName -- ^Server hostname.
-> ServiceName -- ^Server service port.
-> ((Context, SockAddr) -> m r)
-- ^Computation to run after establishing TLS-secured
-- TCP connection to the remote server. Takes the TLS
-- connection context and remote end address.
-> m r
connect cs host port k = C.bracket (connectTls cs host port)
(liftIO . T.contextClose . fst)
(useTls k)
--------------------------------------------------------------------------------
-- | Estalbishes a TCP connection to a remote server and returns a TLS
-- 'Context' configured on top of it using the given 'ClientSettings'.
-- The remote end address is also returned.
--
-- Prefer to use 'connect' if you will be using the obtained 'Context' within a
-- limited scope.
--
-- You need to perform a TLS handshake on the resulting 'Context' before using
-- it for communication purposes, and gracefully close the TLS and TCP
-- connections afterwards using. The 'useTls', 'useTlsThenClose' and
-- 'useTlsThenCloseFork' can help you with that.
connectTls
:: MonadIO m
=> ClientSettings -- ^TLS settings.
-> HostName -- ^Server hostname.
-> ServiceName -- ^Service port to bind.
-> m (Context, SockAddr)
connectTls cs host port = liftIO $ do
E.bracketOnError
(S.connectSock host port)
(S.closeSock . fst)
(\(sock, addr) -> do
ctx <- makeClientContext cs sock
return (ctx, addr))
-- | Make a client-side TLS 'Context' for the given settings, on top of the
-- given TCP `Socket` connected to the remote end.
makeClientContext :: MonadIO m => ClientSettings -> Socket -> m Context
makeClientContext (ClientSettings params) sock = liftIO $ do
T.contextNew (socketBackend sock) params
--------------------------------------------------------------------------------
-- | Accepts an incoming TCP connection and returns a TLS 'Context' configured
-- on top of it using the given 'ServerSettings'. The remote end address is also
-- returned.
--
-- Prefer to use 'accept' if you will be using the obtained 'Context' within a
-- limited scope.
--
-- You need to perform a TLS handshake on the resulting 'Context' before using
-- it for communication purposes, and gracefully close the TLS and TCP
-- connections afterwards using. The 'useTls', 'useTlsThenClose' and
-- 'useTlsThenCloseFork' can help you with that.
acceptTls
:: MonadIO m
=> ServerSettings -- ^TLS settings.
-> Socket -- ^Listening and bound socket.
-> m (Context, SockAddr)
acceptTls sp lsock = liftIO $ do
E.bracketOnError
(NS.accept lsock)
(S.closeSock . fst)
(\(sock, addr) -> do
ctx <- makeServerContext sp sock
return (ctx, addr))
-- | Make a server-side TLS 'Context' for the given settings, on top of the
-- given TCP `Socket` connected to the remote end.
makeServerContext :: MonadIO m => ServerSettings -> Socket -> m Context
makeServerContext (ServerSettings params) sock = liftIO $ do
T.contextNew (socketBackend sock) params
--------------------------------------------------------------------------------
-- | Perform a TLS handshake on the given 'Context', then perform the
-- given action and at last gracefully close the TLS session using `T.bye`.
--
-- This function does not close the underlying TCP connection when done.
-- Prefer to use `useTlsThenClose` or `useTlsThenCloseFork` if you need that
-- behavior. Otherwise, you must call `T.contextClose` yourself at some point.
useTls
:: (MonadIO m, C.MonadMask m)
=> ((Context, SockAddr) -> m a)
-> ((Context, SockAddr) -> m a)
useTls k conn@(ctx,_) = C.bracket_ (T.handshake ctx)
(liftIO $ silentBye ctx)
(k conn)
-- | Like 'useTls', except it also fully closes the TCP connection when done.
useTlsThenClose
:: (MonadIO m, C.MonadMask m)
=> ((Context, SockAddr) -> m a)
-> ((Context, SockAddr) -> m a)
useTlsThenClose k conn@(ctx,_) = do
useTls k conn `C.finally` liftIO (T.contextClose ctx)
-- | Similar to 'useTlsThenClose', except it performs the all the IO actions
-- in a new thread.
--
-- Use this instead of forking `useTlsThenClose` yourself, as that won't give
-- the right behavior.
useTlsThenCloseFork
:: MonadIO m
=> ((Context, SockAddr) -> IO ())
-> ((Context, SockAddr) -> m ThreadId)
useTlsThenCloseFork k conn@(ctx,_) = liftIO $ do
forkFinally (E.bracket_ (T.handshake ctx) (silentBye ctx) (k conn))
(\eu -> T.contextClose ctx >> either E.throwIO return eu)
--------------------------------------------------------------------------------
-- Utils
-- | Receives decrypted bytes from the given 'Context'. Returns 'Nothing'
-- on EOF.
--
-- Up to @16384@ decrypted bytes will be received at once.
recv :: MonadIO m => Context -> m (Maybe B.ByteString)
recv ctx = liftIO $ do
E.handle (\T.Error_EOF -> return Nothing)
(do bs <- T.recvData ctx
if B.null bs
then return Nothing -- I think this never happens
else return (Just bs))
{-# INLINABLE recv #-}
-- | Encrypts the given strict 'B.ByteString' and sends it through the
-- 'Context'.
send :: MonadIO m => Context -> B.ByteString -> m ()
send ctx = \bs -> T.sendData ctx (BL.fromChunks [bs])
{-# INLINABLE send #-}
--------------------------------------------------------------------------------
-- Internal utils
-- | Like 'T.bye' from the "Network.TLS" module, except it ignores 'ePIPE'
-- errors which might happen if the remote peer closes the connection first.
silentBye :: Context -> IO ()
silentBye ctx = do
E.catch (T.bye ctx) $ \e -> case e of
Eg.IOError{ Eg.ioe_type = Eg.ResourceVanished
, Eg.ioe_errno = Just ioe
} | Errno ioe == ePIPE
-> return ()
_ -> E.throwIO e
-- | Makes an TLS context `T.Backend` from a `Socket`.
socketBackend :: Socket -> T.Backend
socketBackend sock = do
T.Backend (return ()) (S.closeSock sock) (NSB.sendAll sock) recvAll
where
recvAll = step B.empty
where step !acc 0 = return acc
step !acc n = do
bs <- NSB.recv sock n
step (acc `B.append` bs) (n - B.length bs)