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{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}
--------------------------------------------------------------------------------
-- | Get a certificate from Let's Encrypt using the ACME protocol.
--
-- https://github.com/ietf-wg-acme/acme/blob/master/draft-ietf-acme-acme.md
module Network.ACME where
import Control.Lens hiding (each, (.=))
import Control.Monad
import Control.Monad.RWS.Strict
import Data.Aeson (Value)
import Data.Aeson.Lens hiding (key)
import qualified Data.Aeson.Lens as JSON
import Data.ByteString (ByteString)
import qualified Data.ByteString.Char8 as BC
import qualified Data.ByteString.Lazy as LB
import qualified Data.ByteString.Lazy.Char8 as LC
import Data.Coerce
import Data.String (fromString)
import qualified Data.Text as T
import Data.Text.Encoding (decodeUtf8, encodeUtf8)
import Data.Time.Clock.POSIX (getPOSIXTime)
import Network.ACME.Encoding
import Network.Wreq (Response, checkStatus, defaults,
responseBody, responseHeader,
responseStatus, statusCode,
statusMessage)
import qualified Network.Wreq as W
import qualified Network.Wreq.Session as WS
import System.Directory
import Text.Email.Validate
import Text.Domain.Validate hiding (validate)
import Network.URI
import OpenSSL
import OpenSSL.EVP.Digest
import OpenSSL.RSA
import OpenSSL.X509.Request
import Data.List
type HttpProvisioner = URI -> ByteString -> IO ()
genReq :: Keys -> [DomainName] -> IO CSR
genReq _ [] = error "genReq called with zero domains"
genReq (Keys priv pub) domains@(domain:_) = withOpenSSL $ do
Just dig <- getDigestByName "SHA256"
req <- newX509Req
setSubjectName req [("CN", domainToString domain)]
setVersion req 0
setPublicKey req pub
void $ addExtensions req [(nidSubjectAltName, intercalate ", " (map (("DNS:" ++) . domainToString) domains))]
signX509Req req priv (Just dig)
CSR domains . toStrict <$> writeX509ReqDER req
where
nidSubjectAltName = 85
fileProvisioner :: WritableDir -> HttpProvisioner
fileProvisioner challengeDir = BC.writeFile . uToF
where
uToF = (coerce challengeDir </>) . takeWhileEnd (/= '/') . uriPath
takeWhileEnd f = reverse . takeWhile f . reverse
acmeChallengeURI :: DomainName -> BC.ByteString -> URI
acmeChallengeURI dom tok = URI
"http:"
(Just $ URIAuth "" (domainToString dom) "")
("/.well-known/acme-challenge" </> BC.unpack tok)
""
""
certify :: URI -> Keys -> Maybe (URI, EmailAddress) -> HttpProvisioner -> CSR -> IO (Either String LC.ByteString)
certify directoryUrl keys reg provision certReq =
runACME directoryUrl keys $ do
forM_ reg $ uncurry register >=> statusReport
let performChallenge domain (ChallengeRequest nextUri token thumbtoken) = do
liftIO $ provision (acmeChallengeURI domain token) thumbtoken
notifyChallenge nextUri thumbtoken >>= statusReport >>= ncErrorReport
challengeResultLinks <- forM (csrDomains certReq) $ \dom ->
challengeRequest dom >>= statusReport >>= extractCR >>= performChallenge dom
pollResults challengeResultLinks >>=
either (return . Left . ("certificate receipt was not attempted because a challenge failed: " ++))
(const (retrieveCert certReq >>= statusReport <&> checkCertResponse))
pollResults :: [Response LC.ByteString] -> ACME (Either String ())
pollResults [] = return $ Right ()
pollResults (link:links) = do
-- TODO: use "Retry-After" header if present
let Just uri = link ^? responseBody . JSON.key "uri" . _String
r <- liftIO $ W.get (T.unpack uri)
let status = r ^. responseBody . JSON.key "status" . _String
case status of
"pending" -> pollResults $ links ++ [r]
"valid" -> pollResults links
"invalid" -> return . Left $ r ^. responseBody . JSON.key "error" . to extractAcmeError
_ -> return . Left $ "unexpected response from ACME server: " ++ show r
data ChallengeRequest = ChallengeRequest { crUri :: String, crToken :: ByteString, crThumbToken :: ByteString }
data CSR = CSR { csrDomains :: [DomainName], csrData :: ByteString }
newtype WritableDir = WritableDir String
ensureWritableDir :: FilePath -> String -> IO WritableDir
ensureWritableDir file name = do
(writable <$> getPermissions file) >>= flip unless (err name)
return $ WritableDir file
where err n = error $ "Error: " ++ n ++ " is not writable"
(</>) :: String -> String -> String
a </> b = a ++ "/" ++ b
infixr 5 </>
domainToString :: DomainName -> String
domainToString = T.unpack . decodeUtf8 . Text.Domain.Validate.toByteString
canProvision :: WritableDir -> DomainName -> IO Bool
canProvision challengeDir domain = do
randomish <- fromString . show <$> getPOSIXTime
let absFile = coerce challengeDir </> relFile
relFile = ".test." ++ show randomish
LC.writeFile absFile randomish
r <- W.get $ "http://" ++ domainToString domain </> ".well-known/acme-challenge" </> relFile
removeFile absFile
return $ r ^. responseBody == randomish
extractCR :: MonadReader Env m => Response LC.ByteString -> m ChallengeRequest
extractCR r = do
Keys _ pub <- asks getKeys
let httpChallenge :: (Value -> Const (Endo s) Value) -> Response LC.ByteString -> Const (Endo s) (Response LC.ByteString)
httpChallenge = responseBody .
JSON.key "challenges" .
to universe .
traverse .
(filtered . has $ ix "type" . only "http-01")
token = r ^?! httpChallenge . JSON.key "token" . _String . to encodeUtf8
nextU = r ^?! httpChallenge . JSON.key "uri" . _String . to T.unpack
thumb = thumbprint (JWK (rsaE pub) "RSA" (rsaN pub))
thumbtoken = toStrict (LB.fromChunks [token, ".", thumb])
return $ ChallengeRequest nextU token thumbtoken
ncErrorReport :: (Show body, AsValue body, MonadIO m) => Response body -> m (Response body)
ncErrorReport r = do
when (Just "pending" /= r ^? responseBody . JSON.key "status" . _String) $ liftIO $ do
putStrLn "Unexpected response to challenge-response request:"
print r
return r
extractAcmeError :: forall s. AsValue s => s -> String
extractAcmeError r = summary ++ " ---- " ++ details
where
(Just summary, Just details) = (k "type", k "detail")
k x = r ^? JSON.key x . _String . to T.unpack
checkCertResponse :: Response LC.ByteString -> Either String LC.ByteString
checkCertResponse r =
if isSuccess $ r ^. responseStatus . statusCode
then Right $ r ^. responseBody
else Left $ r ^. responseBody . to extractAcmeError
where
isSuccess n = n >= 200 && n <= 300
retrieveCert :: (MonadReader Env m, MonadState Nonce m, MonadIO m) => CSR -> m (Response LC.ByteString)
retrieveCert input = sendPayload _newCert (csr $ csrData input)
notifyChallenge :: (MonadReader Env m, MonadState Nonce m, MonadIO m) => String -> ByteString -> m (Response LC.ByteString)
notifyChallenge uri thumbtoken = sendPayload (const uri) (challenge thumbtoken)
data Env = Env { getDir :: Directory, getKeys :: Keys, getSession :: WS.Session }
type ACME = RWST Env () Nonce IO
runACME :: URI -> Keys -> ACME a -> IO a
runACME url keys f = WS.withSession $ \sess -> do
Just (dir, nonce) <- getDirectory sess (show url)
fst <$> evalRWST f (Env dir keys sess) nonce
data Directory = Directory {
_newCert :: String,
_newAuthz :: String,
_revokeCert :: String,
_newReg :: String
}
newtype Nonce = Nonce String
getDirectory :: WS.Session -> String -> IO (Maybe (Directory, Nonce))
getDirectory sess url = do
r <- WS.get sess url
let nonce = r ^? responseHeader "Replay-Nonce" . to (Nonce . T.unpack . decodeUtf8)
k x = r ^? responseBody . JSON.key x . _String . to T.unpack
return $ (,) <$> (Directory <$> k "new-cert" <*> k "new-authz" <*> k "revoke-cert" <*> k "new-reg") <*> nonce
register :: URI -> EmailAddress -> ACME (Response LC.ByteString)
register terms email = sendPayload _newReg (registration email (show terms))
challengeRequest :: (MonadIO m, MonadState Nonce m, MonadReader Env m) => DomainName -> m (Response LC.ByteString)
challengeRequest = sendPayload _newAuthz . authz . domainToString
statusLine :: Response body -> String
statusLine r = (r ^. responseStatus . statusCode . to show) ++ " " ++ r ^. responseStatus . statusMessage . to (T.unpack . decodeUtf8)
statusReport :: MonadIO m => Response body -> m (Response body)
statusReport r = do
liftIO $ putStrLn $ statusLine r
return r
sendPayload :: (MonadIO m, MonadState Nonce m, MonadReader Env m) => (Directory -> String) -> ByteString -> m (Response LC.ByteString)
sendPayload reqType payload = do
keys <- asks getKeys
dir <- asks getDir
nonce <- gets coerce
signed <- liftIO $ signPayload keys nonce payload
post (reqType dir) signed
post :: (MonadReader Env m, MonadState Nonce m, MonadIO m) => String -> LC.ByteString -> m (Response LC.ByteString)
post url payload = do
sess <- asks getSession
r <- liftIO $ WS.postWith noStatusCheck sess url payload
put $ r ^?! responseHeader "Replay-Nonce" . to (Nonce . T.unpack . decodeUtf8)
return r
where
noStatusCheck = defaults & checkStatus .~ Just nullChecker
nullChecker _ _ _ = Nothing
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