More systematic approach to delayed checks.

This introduces a `Delayed` type in `RoutingApplication.hs` that
contains a handler together with delayed checks. There are several
blocks of delayed checks, so that we can ultimately execute them in the
order we desire.

The process is documented in more detail in `RoutingApplication.hs`.
This commit is contained in:
Andres Loeh 2015-09-16 22:07:55 +02:00 committed by Julian K. Arni
parent ccadba81ec
commit 1398d1f5e1
10 changed files with 342 additions and 172 deletions

View file

@ -496,19 +496,6 @@ sampleByteStrings ctypes@Proxy Proxy =
enc (t, s) = uncurry (t,,) <$> allMimeRender ctypes s
in concatMap enc samples'
-- | Generate a list of 'MediaType' values describing the content types
-- accepted by an API component.
class SupportedTypes (list :: [*]) where
supportedTypes :: Proxy list -> [M.MediaType]
instance SupportedTypes '[] where
supportedTypes Proxy = []
instance (Accept ctype, SupportedTypes rest) => SupportedTypes (ctype ': rest)
where
supportedTypes Proxy =
contentType (Proxy :: Proxy ctype) : supportedTypes (Proxy :: Proxy rest)
-- | The class that helps us automatically get documentation
-- for GET parameters.
--
@ -709,14 +696,14 @@ instance
#if MIN_VERSION_base(4,8,0)
{-# OVERLAPPABLe #-}
#endif
(ToSample a, IsNonEmpty cts, AllMimeRender cts a, SupportedTypes cts)
(ToSample a, IsNonEmpty cts, AllMimeRender cts a)
=> HasDocs (Delete cts a) where
docsFor Proxy (endpoint, action) DocOptions{..} =
single endpoint' action'
where endpoint' = endpoint & method .~ DocDELETE
action' = action & response.respBody .~ take _maxSamples (sampleByteStrings t p)
& response.respTypes .~ supportedTypes t
& response.respTypes .~ allMime t
t = Proxy :: Proxy cts
p = Proxy :: Proxy a
@ -724,7 +711,7 @@ instance
#if MIN_VERSION_base(4,8,0)
{-# OVERLAPPING #-}
#endif
(ToSample a, IsNonEmpty cts, AllMimeRender cts a, SupportedTypes cts
(ToSample a, IsNonEmpty cts, AllMimeRender cts a
, AllHeaderSamples ls , GetHeaders (HList ls) )
=> HasDocs (Delete cts (Headers ls a)) where
docsFor Proxy (endpoint, action) DocOptions{..} =
@ -733,7 +720,7 @@ instance
where hdrs = allHeaderToSample (Proxy :: Proxy ls)
endpoint' = endpoint & method .~ DocDELETE
action' = action & response.respBody .~ take _maxSamples (sampleByteStrings t p)
& response.respTypes .~ supportedTypes t
& response.respTypes .~ allMime t
& response.respHeaders .~ hdrs
t = Proxy :: Proxy cts
p = Proxy :: Proxy a
@ -742,14 +729,14 @@ instance
#if MIN_VERSION_base(4,8,0)
{-# OVERLAPPABLe #-}
#endif
(ToSample a, IsNonEmpty cts, AllMimeRender cts a, SupportedTypes cts)
(ToSample a, IsNonEmpty cts, AllMimeRender cts a)
=> HasDocs (Get cts a) where
docsFor Proxy (endpoint, action) DocOptions{..} =
single endpoint' action'
where endpoint' = endpoint & method .~ DocGET
action' = action & response.respBody .~ take _maxSamples (sampleByteStrings t p)
& response.respTypes .~ supportedTypes t
& response.respTypes .~ allMime t
t = Proxy :: Proxy cts
p = Proxy :: Proxy a
@ -757,7 +744,7 @@ instance
#if MIN_VERSION_base(4,8,0)
{-# OVERLAPPING #-}
#endif
(ToSample a, IsNonEmpty cts, AllMimeRender cts a, SupportedTypes cts
(ToSample a, IsNonEmpty cts, AllMimeRender cts a
, AllHeaderSamples ls , GetHeaders (HList ls) )
=> HasDocs (Get cts (Headers ls a)) where
docsFor Proxy (endpoint, action) DocOptions{..} =
@ -766,7 +753,7 @@ instance
where hdrs = allHeaderToSample (Proxy :: Proxy ls)
endpoint' = endpoint & method .~ DocGET
action' = action & response.respBody .~ take _maxSamples (sampleByteStrings t p)
& response.respTypes .~ supportedTypes t
& response.respTypes .~ allMime t
& response.respHeaders .~ hdrs
t = Proxy :: Proxy cts
p = Proxy :: Proxy a
@ -784,14 +771,14 @@ instance
#if MIN_VERSION_base(4,8,0)
{-# OVERLAPPABLE #-}
#endif
(ToSample a, IsNonEmpty cts, AllMimeRender cts a, SupportedTypes cts)
(ToSample a, IsNonEmpty cts, AllMimeRender cts a)
=> HasDocs (Post cts a) where
docsFor Proxy (endpoint, action) DocOptions{..} =
single endpoint' action'
where endpoint' = endpoint & method .~ DocPOST
action' = action & response.respBody .~ take _maxSamples (sampleByteStrings t p)
& response.respTypes .~ supportedTypes t
& response.respTypes .~ allMime t
& response.respStatus .~ 201
t = Proxy :: Proxy cts
p = Proxy :: Proxy a
@ -800,7 +787,7 @@ instance
#if MIN_VERSION_base(4,8,0)
{-# OVERLAPPING #-}
#endif
(ToSample a, IsNonEmpty cts, AllMimeRender cts a, SupportedTypes cts
(ToSample a, IsNonEmpty cts, AllMimeRender cts a
, AllHeaderSamples ls , GetHeaders (HList ls) )
=> HasDocs (Post cts (Headers ls a)) where
docsFor Proxy (endpoint, action) DocOptions{..} =
@ -809,7 +796,7 @@ instance
where hdrs = allHeaderToSample (Proxy :: Proxy ls)
endpoint' = endpoint & method .~ DocPOST
action' = action & response.respBody .~ take _maxSamples (sampleByteStrings t p)
& response.respTypes .~ supportedTypes t
& response.respTypes .~ allMime t
& response.respStatus .~ 201
& response.respHeaders .~ hdrs
t = Proxy :: Proxy cts
@ -819,14 +806,14 @@ instance
#if MIN_VERSION_base(4,8,0)
{-# OVERLAPPABLE #-}
#endif
(ToSample a, IsNonEmpty cts, AllMimeRender cts a, SupportedTypes cts)
(ToSample a, IsNonEmpty cts, AllMimeRender cts a)
=> HasDocs (Put cts a) where
docsFor Proxy (endpoint, action) DocOptions{..} =
single endpoint' action'
where endpoint' = endpoint & method .~ DocPUT
action' = action & response.respBody .~ take _maxSamples (sampleByteStrings t p)
& response.respTypes .~ supportedTypes t
& response.respTypes .~ allMime t
& response.respStatus .~ 200
t = Proxy :: Proxy cts
p = Proxy :: Proxy a
@ -835,8 +822,8 @@ instance
#if MIN_VERSION_base(4,8,0)
{-# OVERLAPPING #-}
#endif
(ToSample a, IsNonEmpty cts, AllMimeRender cts a, SupportedTypes cts
, AllHeaderSamples ls , GetHeaders (HList ls) )
( ToSample a, IsNonEmpty cts, AllMimeRender cts a,
AllHeaderSamples ls , GetHeaders (HList ls) )
=> HasDocs (Put cts (Headers ls a)) where
docsFor Proxy (endpoint, action) DocOptions{..} =
single endpoint' action'
@ -844,7 +831,7 @@ instance
where hdrs = allHeaderToSample (Proxy :: Proxy ls)
endpoint' = endpoint & method .~ DocPUT
action' = action & response.respBody .~ take _maxSamples (sampleByteStrings t p)
& response.respTypes .~ supportedTypes t
& response.respTypes .~ allMime t
& response.respStatus .~ 200
& response.respHeaders .~ hdrs
t = Proxy :: Proxy cts
@ -890,8 +877,7 @@ instance HasDocs Raw where
-- example data. However, there's no reason to believe that the instances of
-- 'AllMimeUnrender' and 'AllMimeRender' actually agree (or to suppose that
-- both are even defined) for any particular type.
instance (ToSample a, IsNonEmpty cts, AllMimeRender cts a, HasDocs sublayout
, SupportedTypes cts)
instance (ToSample a, IsNonEmpty cts, AllMimeRender cts a, HasDocs sublayout)
=> HasDocs (ReqBody cts a :> sublayout) where
docsFor Proxy (endpoint, action) =
@ -899,7 +885,7 @@ instance (ToSample a, IsNonEmpty cts, AllMimeRender cts a, HasDocs sublayout
where sublayoutP = Proxy :: Proxy sublayout
action' = action & rqbody .~ sampleByteString t p
& rqtypes .~ supportedTypes t
& rqtypes .~ allMime t
t = Proxy :: Proxy cts
p = Proxy :: Proxy a
@ -957,4 +943,3 @@ instance ToSample a => ToSample (Product a)
instance ToSample a => ToSample (First a)
instance ToSample a => ToSample (Last a)
instance ToSample a => ToSample (Dual a)

View file

@ -10,7 +10,6 @@ import Data.Aeson
import Data.ByteString (ByteString)
import Data.Text (Text)
import GHC.Generics
import Network.HTTP.Types
import Network.Wai
import Network.Wai.Handler.Warp
import Servant
@ -29,14 +28,15 @@ data AuthProtected
instance HasServer rest => HasServer (AuthProtected :> rest) where
type ServerT (AuthProtected :> rest) m = ServerT rest m
route Proxy a = WithRequest $ \ request ->
route (Proxy :: Proxy rest) $ do
case lookup "Cookie" (requestHeaders request) of
Nothing -> return $! FailFatal err401 { errBody = "Missing auth header" }
route Proxy subserver = WithRequest $ \ request ->
route (Proxy :: Proxy rest) $ addAcceptCheck subserver $ cookieCheck request
where
cookieCheck req = case lookup "Cookie" (requestHeaders req) of
Nothing -> return $ FailFatal err401 { errBody = "Missing auth header" }
Just v -> do
authGranted <- isGoodCookie v
if authGranted
then a
then return $ Route ()
else return $ FailFatal err403 { errBody = "Invalid cookie" }
type PrivateAPI = Get '[JSON] [PrivateData]

View file

@ -108,6 +108,7 @@ test-suite spec
, network >= 2.6
, QuickCheck
, parsec
, safe
, servant
, servant-server
, string-conversions

View file

@ -103,7 +103,10 @@ import Servant.Server.Internal.Enter
-- > main = Network.Wai.Handler.Warp.run 8080 app
--
serve :: HasServer layout => Proxy layout -> Server layout -> Application
serve p server = toApplication (runRouter (route p (return (Route server))))
serve p server = toApplication (runRouter (route p d))
where
d = Delayed r r r (\ _ _ -> Route server)
r = return (Route ())
-- Documentation

View file

@ -46,7 +46,9 @@ import Servant.API ((:<|>) (..), (:>), Capture,
Raw, RemoteHost, ReqBody, Vault)
import Servant.API.ContentTypes (AcceptHeader (..),
AllCTRender (..),
AllCTUnrender (..))
AllCTUnrender (..),
AllMime,
canHandleAcceptH)
import Servant.API.ResponseHeaders (GetHeaders, Headers, getHeaders,
getResponse)
@ -60,7 +62,7 @@ import Web.HttpApiData.Internal (parseUrlPieceMaybe, parseHeaderMaybe,
class HasServer layout where
type ServerT layout (m :: * -> *) :: *
route :: Proxy layout -> IO (RouteResult (Server layout)) -> Router
route :: Proxy layout -> Delayed (Server layout) -> Router
type Server layout = ServerT layout (ExceptT ServantErr IO)
@ -81,8 +83,8 @@ instance (HasServer a, HasServer b) => HasServer (a :<|> b) where
type ServerT (a :<|> b) m = ServerT a m :<|> ServerT b m
route Proxy server = choice (route pa (extractL <$> server))
(route pb (extractR <$> server))
route Proxy server = choice (route pa ((\ (a :<|> _) -> a) <$> server))
(route pb ((\ (_ :<|> b) -> b) <$> server))
where pa = Proxy :: Proxy a
pb = Proxy :: Proxy b
@ -112,12 +114,15 @@ instance (KnownSymbol capture, FromHttpApiData a, HasServer sublayout)
type ServerT (Capture capture a :> sublayout) m =
a -> ServerT sublayout m
route Proxy subserver =
DynamicRouter $ \ first -> case captured captureProxy first of
Nothing -> LeafRouter (\_ r -> r $ Fail err404)
Just v -> route (Proxy :: Proxy sublayout) (feedTo subserver v)
where captureProxy = Proxy :: Proxy (Capture capture a)
route Proxy d =
DynamicRouter $ \ first ->
route (Proxy :: Proxy sublayout)
(addCapture d $ case captured captureProxy first of
Nothing -> return $ Fail err404
Just v -> return $ Route v
)
where
captureProxy = Proxy :: Proxy (Capture capture a)
allowedMethodHead :: Method -> Request -> Bool
allowedMethodHead method request = method == methodGet && requestMethod request == methodHead
@ -130,56 +135,64 @@ processMethodRouter :: forall a. ConvertibleStrings a B.ByteString
-> Maybe [(HeaderName, B.ByteString)]
-> Request -> RouteResult Response
processMethodRouter handleA status method headers request = case handleA of
Nothing -> FailFatal err406
Just (contentT, body) -> Route $! responseLBS status hdrs bdy
Nothing -> FailFatal err406 -- this should not happen (checked before), so we make it fatal if it does
Just (contentT, body) -> Route $ responseLBS status hdrs bdy
where
bdy = if allowedMethodHead method request then "" else body
hdrs = (hContentType, cs contentT) : (fromMaybe [] headers)
methodCheck :: Method -> Request -> IO (RouteResult ())
methodCheck method request
| allowedMethod method request = return $ Route ()
| otherwise = return $ Fail err405
acceptCheck :: (AllMime list) => Proxy list -> B.ByteString -> IO (RouteResult ())
acceptCheck proxy accH
| canHandleAcceptH proxy (AcceptHeader accH) = return $ Route ()
| otherwise = return $ Fail err406
methodRouter :: (AllCTRender ctypes a)
=> Method -> Proxy ctypes -> Status
-> IO (RouteResult (ExceptT ServantErr IO a))
-> Delayed (ExceptT ServantErr IO a)
-> Router
methodRouter method proxy status action = LeafRouter route'
where
route' request respond
| pathIsEmpty request && allowedMethod method request = do
runAction action respond $ \ output -> do
| pathIsEmpty request =
let accH = fromMaybe ct_wildcard $ lookup hAccept $ requestHeaders request
handleA = handleAcceptH proxy (AcceptHeader accH) output
in runAction (action `addMethodCheck` methodCheck method request
`addAcceptCheck` acceptCheck proxy accH
) respond $ \ output -> do
let handleA = handleAcceptH proxy (AcceptHeader accH) output
processMethodRouter handleA status method Nothing request
| pathIsEmpty request && requestMethod request /= method =
respond $ Fail err405
| otherwise = respond $ Fail err404
methodRouterHeaders :: (GetHeaders (Headers h v), AllCTRender ctypes v)
=> Method -> Proxy ctypes -> Status
-> IO (RouteResult (ExceptT ServantErr IO (Headers h v)))
-> Delayed (ExceptT ServantErr IO (Headers h v))
-> Router
methodRouterHeaders method proxy status action = LeafRouter route'
where
route' request respond
| pathIsEmpty request && allowedMethod method request = do
runAction action respond $ \ output -> do
| pathIsEmpty request =
let accH = fromMaybe ct_wildcard $ lookup hAccept $ requestHeaders request
headers = getHeaders output
in runAction (action `addMethodCheck` methodCheck method request
`addAcceptCheck` acceptCheck proxy accH
) respond $ \ output -> do
let headers = getHeaders output
handleA = handleAcceptH proxy (AcceptHeader accH) (getResponse output)
processMethodRouter handleA status method (Just headers) request
| pathIsEmpty request && requestMethod request /= method =
respond $ Fail err405
| otherwise = respond $ Fail err404
methodRouterEmpty :: Method
-> IO (RouteResult (ExceptT ServantErr IO ()))
-> Delayed (ExceptT ServantErr IO ())
-> Router
methodRouterEmpty method action = LeafRouter route'
where
route' request respond
| pathIsEmpty request && allowedMethod method request = do
runAction action respond $ \ () ->
| pathIsEmpty request = do
runAction (addMethodCheck action (methodCheck method request)) respond $ \ () ->
Route $! responseLBS noContent204 [] ""
| pathIsEmpty request && requestMethod request /= method =
respond $ Fail err405
| otherwise = respond $ Fail err404
-- | If you have a 'Delete' endpoint in your API,
@ -300,7 +313,7 @@ instance (KnownSymbol sym, FromHttpApiData a, HasServer sublayout)
route Proxy subserver = WithRequest $ \ request ->
let mheader = parseHeaderMaybe =<< lookup str (requestHeaders request)
in route (Proxy :: Proxy sublayout) (feedTo subserver mheader)
in route (Proxy :: Proxy sublayout) (passToServer subserver mheader)
where str = fromString $ symbolVal (Proxy :: Proxy sym)
-- | When implementing the handler for a 'Post' endpoint,
@ -472,7 +485,7 @@ instance (KnownSymbol sym, FromHttpApiData a, HasServer sublayout)
Just Nothing -> Nothing -- param present with no value -> Nothing
Just (Just v) -> parseQueryParamMaybe v -- if present, we try to convert to
-- the right type
in route (Proxy :: Proxy sublayout) (feedTo subserver param)
in route (Proxy :: Proxy sublayout) (passToServer subserver param)
where paramname = cs $ symbolVal (Proxy :: Proxy sym)
-- | If you use @'QueryParams' "authors" Text@ in one of the endpoints for your API,
@ -507,7 +520,7 @@ instance (KnownSymbol sym, FromHttpApiData a, HasServer sublayout)
-- corresponding values
parameters = filter looksLikeParam querytext
values = mapMaybe (convert . snd) parameters
in route (Proxy :: Proxy sublayout) (feedTo subserver values)
in route (Proxy :: Proxy sublayout) (passToServer subserver values)
where paramname = cs $ symbolVal (Proxy :: Proxy sym)
looksLikeParam (name, _) = name == paramname || name == (paramname <> "[]")
convert Nothing = Nothing
@ -537,7 +550,7 @@ instance (KnownSymbol sym, HasServer sublayout)
Just Nothing -> True -- param is there, with no value
Just (Just v) -> examine v -- param with a value
Nothing -> False -- param not in the query string
in route (Proxy :: Proxy sublayout) (feedTo subserver param)
in route (Proxy :: Proxy sublayout) (passToServer subserver param)
where paramname = cs $ symbolVal (Proxy :: Proxy sym)
examine v | v == "true" || v == "1" || v == "" = True
| otherwise = False
@ -555,7 +568,7 @@ instance HasServer Raw where
type ServerT Raw m = Application
route Proxy rawApplication = LeafRouter $ \ request respond -> do
r <- rawApplication
r <- runDelayed rawApplication
case r of
Route app -> app request (respond . Route)
Fail a -> respond $ Fail a
@ -589,7 +602,9 @@ instance ( AllCTUnrender list a, HasServer sublayout
a -> ServerT sublayout m
route Proxy subserver = WithRequest $ \ request ->
route (Proxy :: Proxy sublayout) $ do
route (Proxy :: Proxy sublayout) (addBodyCheck subserver (bodyCheck request))
where
bodyCheck request = do
-- See HTTP RFC 2616, section 7.2.1
-- http://www.w3.org/Protocols/rfc2616/rfc2616-sec7.html#sec7.2.1
-- See also "W3C Internet Media Type registration, consistency of use"
@ -601,7 +616,7 @@ instance ( AllCTUnrender list a, HasServer sublayout
case mrqbody of
Nothing -> return $ FailFatal err415
Just (Left e) -> return $ FailFatal err400 { errBody = cs e }
Just (Right v) -> feedTo subserver v
Just (Right v) -> return $ Route v
-- | Make sure the incoming request starts with @"/path"@, strip it and
-- pass the rest of the request path to @sublayout@.
@ -618,13 +633,13 @@ instance HasServer api => HasServer (RemoteHost :> api) where
type ServerT (RemoteHost :> api) m = SockAddr -> ServerT api m
route Proxy subserver = WithRequest $ \req ->
route (Proxy :: Proxy api) (feedTo subserver $ remoteHost req)
route (Proxy :: Proxy api) (passToServer subserver $ remoteHost req)
instance HasServer api => HasServer (IsSecure :> api) where
type ServerT (IsSecure :> api) m = IsSecure -> ServerT api m
route Proxy subserver = WithRequest $ \req ->
route (Proxy :: Proxy api) (feedTo subserver $ secure req)
route (Proxy :: Proxy api) (passToServer subserver $ secure req)
where secure req = if isSecure req then Secure else NotSecure
@ -632,13 +647,13 @@ instance HasServer api => HasServer (Vault :> api) where
type ServerT (Vault :> api) m = Vault -> ServerT api m
route Proxy subserver = WithRequest $ \req ->
route (Proxy :: Proxy api) (feedTo subserver $ vault req)
route (Proxy :: Proxy api) (passToServer subserver $ vault req)
instance HasServer api => HasServer (HttpVersion :> api) where
type ServerT (HttpVersion :> api) m = HttpVersion -> ServerT api m
route Proxy subserver = WithRequest $ \req ->
route (Proxy :: Proxy api) (feedTo subserver $ httpVersion req)
route (Proxy :: Proxy api) (passToServer subserver $ httpVersion req)
pathIsEmpty :: Request -> Bool
pathIsEmpty = go . pathInfo

View file

@ -6,9 +6,9 @@ import Data.Map (Map)
import qualified Data.Map as M
import Data.Text (Text)
import Network.Wai (Request, Response, pathInfo)
import Servant.Server.Internal.ServantErr
import Servant.Server.Internal.PathInfo
import Servant.Server.Internal.RoutingApplication
import Servant.Server.Internal.ServantErr
type Router = Router' RoutingApplication
@ -79,8 +79,16 @@ runRouter (Choice r1 r2) request respond =
_ -> respond mResponse1
where
highestPri (Fail e1) (Fail e2) =
if errHTTPCode e1 == 404 && errHTTPCode e2 /= 404
if worseHTTPCode (errHTTPCode e1) (errHTTPCode e2)
then Fail e2
else Fail e1
highestPri (Fail _) y = y
highestPri x _ = x
-- Priority on HTTP codes.
--
-- It just so happens that 404 < 405 < 406 as far as
-- we are concerned here, so we can use (<).
worseHTTPCode :: Int -> Int -> Bool
worseHTTPCode = (<)

View file

@ -2,6 +2,9 @@
{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE StandaloneDeriving #-}
module Servant.Server.Internal.RoutingApplication where
#if !MIN_VERSION_base(4,8,0)
@ -18,19 +21,18 @@ import Network.Wai (Application, Request,
Response, ResponseReceived,
requestBody,
strictRequestBody)
import Servant.API ((:<|>) (..))
import Servant.Server.Internal.ServantErr
type RoutingApplication =
Request -- ^ the request, the field 'pathInfo' may be modified by url routing
-> (RouteResult Response -> IO ResponseReceived) -> IO ResponseReceived
-- | A wrapper around @'Either' 'RouteMismatch' a@.
-- | The result of matching against a path in the route tree.
data RouteResult a =
Fail ServantErr -- ^ Keep trying other paths. The @ServantErr@
-- should only be 404 or 405.
| FailFatal ServantErr -- ^ Don't other paths.
| Route a
-- should only be 404, 405 or 406.
| FailFatal !ServantErr -- ^ Don't try other paths.
| Route !a
deriving (Eq, Show, Read, Functor)
data ReqBodyState = Uncalled
@ -63,15 +65,183 @@ toApplication ra request respond = do
ra request{ requestBody = memoReqBody } routingRespond
where
routingRespond :: RouteResult Response -> IO ResponseReceived
routingRespond (Fail err) = respond $! responseServantErr err
routingRespond (FailFatal err) = respond $! responseServantErr err
routingRespond (Fail err) = respond $ responseServantErr err
routingRespond (FailFatal err) = respond $ responseServantErr err
routingRespond (Route v) = respond v
runAction :: IO (RouteResult (ExceptT ServantErr IO a))
-- TODO: The above may not be quite right yet.
--
-- We currently mix up the order in which we perform checks
-- and the priority with which errors are reported.
--
-- For example, we perform Capture checks prior to method checks,
-- and therefore get 404 before 405.
--
-- However, we also perform body checks prior to method checks
-- now, and therefore get 415 before 405, which is wrong.
--
-- If we delay Captures, but perform method checks eagerly, we
-- end up potentially preferring 405 over 404, whcih is also bad.
--
-- So in principle, we'd like:
--
-- static routes (can cause 404)
-- delayed captures (can cause 404)
-- methods (can cause 405)
-- delayed body (can cause 415, 400)
-- accept header (can cause 406)
--
-- According to the HTTP decision diagram, the priority order
-- between HTTP status codes is as follows:
--
-- | A 'Delayed' is a representation of a handler with scheduled
-- delayed checks that can trigger errors.
--
-- Why would we want to delay checks?
--
-- There are two reasons:
--
-- 1. Currently, the order in which we perform checks coincides
-- with the error we will generate. This is because during checks,
-- once an error occurs, we do not perform any subsequent checks,
-- but rather return this error.
--
-- This is not a necessity: we could continue doing other checks,
-- and choose the preferred error. However, that would in general
-- mean more checking, which leads us to the other reason.
--
-- 2. We really want to avoid doing certain checks too early. For
-- example, captures involve parsing, and are much more costly
-- than static route matches. In particular, if several paths
-- contain the "same" capture, we'd like as much as possible to
-- avoid trying the same parse many times. Also tricky is the
-- request body. Again, this involves parsing, but also, WAI makes
-- obtaining the request body a side-effecting operation. We
-- could/can work around this by manually caching the request body,
-- but we'd rather keep the number of times we actually try to
-- decode the request body to an absolute minimum.
--
-- We prefer to have the following relative priorities of error
-- codes:
--
-- @
-- 404
-- 405 (bad method)
-- 401 (unauthorized)
-- 415 (unsupported media type)
-- 400 (bad request)
-- 406 (not acceptable)
-- @
--
-- Therefore, while routing, we delay most checks so that they
-- will ultimately occur in the right order.
--
-- A 'Delayed' contains three delayed blocks of tests, and
-- the actual handler:
--
-- 1. Delayed captures. These can actually cause 404, and
-- while they're costly, they should be done first among the
-- delayed checks (at least as long as we do not decouple the
-- check order from the error reporting, see above). Delayed
-- captures can provide inputs to the actual handler.
--
-- 2. Method check(s). This can cause a 405. On success,
-- it does not provide an input for the handler. Method checks
-- are comparatively cheap.
--
-- 3. Body and accept header checks. The request body check can
-- cause both 400 and 415. This provides an input to the handler.
-- The accept header check can be performed as the final
-- computation in this block. It can cause a 406.
--
data Delayed :: * -> * where
Delayed :: IO (RouteResult a)
-> IO (RouteResult ())
-> IO (RouteResult b)
-> (a -> b -> RouteResult c)
-> Delayed c
deriving instance Functor Delayed
-- | Add a capture to the end of the capture block.
addCapture :: Delayed (a -> b)
-> IO (RouteResult a)
-> Delayed b
addCapture (Delayed captures method body server) new =
Delayed (combineRouteResults (,) captures new) method body (\ (x, v) y -> ($ v) <$> server x y)
-- | Add a method check to the end of the method block.
addMethodCheck :: Delayed a
-> IO (RouteResult ())
-> Delayed a
addMethodCheck (Delayed captures method body server) new =
Delayed captures (combineRouteResults const method new) body server
-- | Add a body check to the end of the body block.
addBodyCheck :: Delayed (a -> b)
-> IO (RouteResult a)
-> Delayed b
addBodyCheck (Delayed captures method body server) new =
Delayed captures method (combineRouteResults (,) body new) (\ x (y, v) -> ($ v) <$> server x y)
-- | Add an accept header check to the end of the body block.
-- The accept header check should occur after the body check,
-- but this will be the case, because the accept header check
-- is only scheduled by the method combinators.
addAcceptCheck :: Delayed a
-> IO (RouteResult ())
-> Delayed a
addAcceptCheck (Delayed captures method body server) new =
Delayed captures method (combineRouteResults const body new) server
-- | Many combinators extract information that is passed to
-- the handler without the possibility of failure. In such a
-- case, 'passToServer' can be used.
passToServer :: Delayed (a -> b) -> a -> Delayed b
passToServer d x = ($ x) <$> d
-- | The combination 'IO . RouteResult' is a monad, but we
-- don't explicitly wrap it in a newtype in order to make it
-- an instance. This is the '>>=' of that monad.
--
-- We stop on the first error.
bindRouteResults :: IO (RouteResult a) -> (a -> IO (RouteResult b)) -> IO (RouteResult b)
bindRouteResults m f = do
r <- m
case r of
Fail e -> return $ Fail e
FailFatal e -> return $ FailFatal e
Route a -> f a
-- | Common special case of 'bindRouteResults', corresponding
-- to 'liftM2'.
combineRouteResults :: (a -> b -> c) -> IO (RouteResult a) -> IO (RouteResult b) -> IO (RouteResult c)
combineRouteResults f m1 m2 =
m1 `bindRouteResults` \ a ->
m2 `bindRouteResults` \ b ->
return (Route (f a b))
-- | Run a delayed server. Performs all scheduled operations
-- in order, and passes the results from the capture and body
-- blocks on to the actual handler.
runDelayed :: Delayed a
-> IO (RouteResult a)
runDelayed (Delayed captures method body server) =
captures `bindRouteResults` \ c ->
method `bindRouteResults` \ _ ->
body `bindRouteResults` \ b ->
return (server c b)
-- | Runs a delayed server and the resulting action.
-- Takes a continuation that lets us send a response.
-- Also takes a continuation for how to turn the
-- result of the delayed server into a response.
runAction :: Delayed (ExceptT ServantErr IO a)
-> (RouteResult Response -> IO r)
-> (a -> RouteResult Response)
-> IO r
runAction action respond k = action >>= go >>= respond
runAction action respond k = runDelayed action >>= go >>= respond
where
go (Fail e) = return $ Fail e
go (FailFatal e) = return $ FailFatal e
@ -80,16 +250,3 @@ runAction action respond k = action >>= go >>= respond
case e of
Left err -> return . Route $ responseServantErr err
Right x -> return $! k x
feedTo :: IO (RouteResult (a -> b)) -> a -> IO (RouteResult b)
feedTo f x = (($ x) <$>) <$> f
extractL :: RouteResult (a :<|> b) -> RouteResult a
extractL (Route (a :<|> _)) = Route a
extractL (Fail x) = Fail x
extractL (FailFatal x) = FailFatal x
extractR :: RouteResult (a :<|> b) -> RouteResult b
extractR (Route (_ :<|> b)) = Route b
extractR (Fail x) = Fail x
extractR (FailFatal x) = FailFatal x

View file

@ -5,12 +5,14 @@
{-# OPTIONS_GHC -fno-warn-orphans #-}
module Servant.Server.ErrorSpec (spec) where
import Control.Monad.Trans.Except (throwE)
import Data.Aeson (encode)
import qualified Data.ByteString.Lazy.Char8 as BCL
import qualified Data.ByteString.Char8 as BC
import qualified Data.ByteString.Lazy.Char8 as BCL
import Data.Proxy
import Network.HTTP.Types (hAccept, hContentType, methodGet,
methodPost, methodPut)
import Safe (readMay)
import Test.Hspec
import Test.Hspec.Wai
@ -54,7 +56,7 @@ errorOrderApi :: Proxy ErrorOrderApi
errorOrderApi = Proxy
errorOrderServer :: Server ErrorOrderApi
errorOrderServer = \_ _ -> return 5
errorOrderServer = \_ _ -> throwE err402
errorOrderSpec :: Spec
errorOrderSpec = describe "HTTP error order"
@ -65,6 +67,7 @@ errorOrderSpec = describe "HTTP error order"
badUrl = "home/nonexistent"
badBody = "nonsense"
goodContentType = (hContentType, "application/json")
goodAccept = (hAccept, "application/json")
goodMethod = methodPost
goodUrl = "home/2"
goodBody = encode (5 :: Int)
@ -89,6 +92,10 @@ errorOrderSpec = describe "HTTP error order"
request goodMethod goodUrl [goodContentType, badAccept] goodBody
`shouldRespondWith` 406
it "has handler-level errors as last priority" $ do
request goodMethod goodUrl [goodContentType, goodAccept] goodBody
`shouldRespondWith` 402
type PrioErrorsApi = ReqBody '[JSON] Integer :> "foo" :> Get '[JSON] Integer
prioErrorsApi :: Proxy PrioErrorsApi
@ -107,7 +114,7 @@ prioErrorsSpec = describe "PrioErrors" $ do
`shouldRespondWith` resp
where
fulldescr = "returns " ++ show (matchStatus resp) ++ " on " ++ mdescr
++ " " ++ (BC.unpack path) ++ " (" ++ cdescr ++ ")"
++ " " ++ BC.unpack path ++ " (" ++ cdescr ++ ")"
get' = ("GET", methodGet)
put' = ("PUT", methodPut)
@ -140,7 +147,7 @@ prioErrorsSpec = describe "PrioErrors" $ do
-- * Error Retry {{{
type ErrorRetryApi
= "a" :> ReqBody '[JSON] Int :> Post '[JSON] Int -- 0
= "a" :> ReqBody '[JSON] Int :> Post '[JSON] Int -- err402
:<|> "a" :> ReqBody '[PlainText] Int :> Post '[JSON] Int -- 1
:<|> "a" :> ReqBody '[JSON] Int :> Post '[PlainText] Int -- 2
:<|> "a" :> ReqBody '[JSON] String :> Post '[JSON] Int -- 3
@ -154,7 +161,7 @@ errorRetryApi = Proxy
errorRetryServer :: Server ErrorRetryApi
errorRetryServer
= (\_ -> return 0)
= (\_ -> throwE err402)
:<|> (\_ -> return 1)
:<|> (\_ -> return 2)
:<|> (\_ -> return 3)
@ -181,18 +188,6 @@ errorRetrySpec = describe "Handler search"
request methodGet "a" [jsonCT, jsonAccept] jsonBody
`shouldRespondWith` 200 { matchBody = Just $ encode (4 :: Int) }
it "should not continue when Content-Types don't match" $ do
request methodPost "a" [plainCT, jsonAccept] jsonBody
`shouldRespondWith` 415
it "should not continue when body can't be deserialized" $ do
request methodPost "a" [jsonCT, jsonAccept] (encode ("nonsense" :: String))
`shouldRespondWith` 400
it "should not continue when Accepts don't match" $ do
request methodPost "a" [jsonCT, plainAccept] jsonBody
`shouldRespondWith` 406
-- }}}
------------------------------------------------------------------------------
-- * Error Choice {{{
@ -233,7 +228,7 @@ errorChoiceSpec = describe "Multiple handlers return errors"
request methodPost "path3" [(hContentType, "application/json")] ""
`shouldRespondWith` 400
request methodPost "path4" [(hContentType, "text/plain;charset=utf-8"),
(hAccept, "application/json")] ""
(hAccept, "blah")] "5"
`shouldRespondWith` 406
@ -242,10 +237,8 @@ errorChoiceSpec = describe "Multiple handlers return errors"
-- * Instances {{{
instance MimeUnrender PlainText Int where
mimeUnrender _ = Right . read . BCL.unpack
mimeUnrender _ x = maybe (Left "no parse") Right (readMay $ BCL.unpack x)
instance MimeRender PlainText Int where
mimeRender _ = BCL.pack . show
-- }}}
--

View file

@ -1,20 +1,12 @@
<<<<<<< HEAD
{-# LANGUAGE CPP #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveGeneric #-}
=======
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE FlexibleInstances #-}
>>>>>>> Review fixes
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE TypeSynonymInstances #-}
<<<<<<< HEAD
{-# LANGUAGE FlexibleInstances #-}
=======
>>>>>>> Review fixes
module Servant.ServerSpec where
@ -55,6 +47,7 @@ import Test.Hspec (Spec, describe, it, shouldBe)
import Test.Hspec.Wai (get, liftIO, matchHeaders,
matchStatus, post, request,
shouldRespondWith, with, (<:>))
<<<<<<< HEAD
import Servant.API ((:<|>) (..), (:>), Capture, Delete,
Get, Header (..), Headers,
HttpVersion, IsSecure (..), JSON,
@ -63,12 +56,12 @@ import Servant.API ((:<|>) (..), (:>), Capture, Delete,
Raw, RemoteHost, ReqBody,
addHeader)
import Servant.Server (Server, serve, ServantErr(..), err404)
=======
import Servant.Server.Internal.RoutingApplication (toApplication, RouteResult(..))
>>>>>>> Rebase cleanup and test fixes.
import Servant.Server.Internal.Router
(tweakResponse, runRouter,
Router, Router'(LeafRouter))
import Servant.Server.Internal.RoutingApplication
(RouteResult(..), RouteMismatch(..),
toApplication)
-- * test data types
@ -279,13 +272,13 @@ queryParamSpec = do
}
let params3'' = "?unknown="
response3' <- Network.Wai.Test.request defaultRequest{
response3'' <- Network.Wai.Test.request defaultRequest{
rawQueryString = params3'',
queryString = parseQuery params3'',
pathInfo = ["b"]
}
liftIO $
decode' (simpleBody response3') `shouldBe` Just alice{
decode' (simpleBody response3'') `shouldBe` Just alice{
name = "Alice"
}
@ -553,7 +546,7 @@ routerSpec = do
router', router :: Router
router' = tweakResponse (twk <$>) router
router = LeafRouter $ \_ cont -> cont (RR . Right $ responseBuilder (Status 201 "") [] "")
router = LeafRouter $ \_ cont -> cont (Route $ responseBuilder (Status 201 "") [] "")
twk :: Response -> Response
twk (ResponseBuilder (Status i s) hs b) = ResponseBuilder (Status (i + 1) s) hs b

View file

@ -57,12 +57,14 @@ module Servant.API.ContentTypes
, AcceptHeader(..)
, AllCTRender(..)
, AllCTUnrender(..)
, AllMime(..)
, AllMimeRender(..)
, AllMimeUnrender(..)
, FromFormUrlEncoded(..)
, ToFormUrlEncoded(..)
, IsNonEmpty
, eitherDecodeLenient
, canHandleAcceptH
) where
#if !MIN_VERSION_base(4,8,0)
@ -81,6 +83,7 @@ import Data.ByteString.Lazy (ByteString, fromStrict,
toStrict)
import qualified Data.ByteString.Lazy as B
import qualified Data.ByteString.Lazy.Char8 as BC
import Data.Maybe (isJust)
import Data.Monoid
import Data.String.Conversions (cs)
import qualified Data.Text as TextS
@ -156,14 +159,13 @@ newtype AcceptHeader = AcceptHeader BS.ByteString
class Accept ctype => MimeRender ctype a where
mimeRender :: Proxy ctype -> a -> ByteString
class AllCTRender (list :: [*]) a where
class (AllMimeRender list a) => AllCTRender (list :: [*]) a where
-- If the Accept header can be matched, returns (Just) a tuple of the
-- Content-Type and response (serialization of @a@ into the appropriate
-- mimetype).
handleAcceptH :: Proxy list -> AcceptHeader -> a -> Maybe (ByteString, ByteString)
instance ( AllMimeRender ctyps a, IsNonEmpty ctyps
) => AllCTRender ctyps a where
instance (AllMimeRender ctyps a, IsNonEmpty ctyps) => AllCTRender ctyps a where
handleAcceptH _ (AcceptHeader accept) val = M.mapAcceptMedia lkup accept
where pctyps = Proxy :: Proxy ctyps
amrs = allMimeRender pctyps val
@ -211,11 +213,24 @@ instance ( AllMimeUnrender ctyps a, IsNonEmpty ctyps
--------------------------------------------------------------------------
-- * Utils (Internal)
class AllMime (list :: [*]) where
allMime :: Proxy list -> [M.MediaType]
instance AllMime '[] where
allMime _ = []
instance (Accept ctyp, AllMime ctyps) => AllMime (ctyp ': ctyps) where
allMime _ = (contentType pctyp):allMime pctyps
where pctyp = Proxy :: Proxy ctyp
pctyps = Proxy :: Proxy ctyps
canHandleAcceptH :: AllMime list => Proxy list -> AcceptHeader -> Bool
canHandleAcceptH p (AcceptHeader h ) = isJust $ M.matchAccept (allMime p) h
--------------------------------------------------------------------------
-- Check that all elements of list are instances of MimeRender
--------------------------------------------------------------------------
class AllMimeRender (list :: [*]) a where
class (AllMime list) => AllMimeRender (list :: [*]) a where
allMimeRender :: Proxy list
-> a -- value to serialize
-> [(M.MediaType, ByteString)] -- content-types/response pairs
@ -239,7 +254,7 @@ instance AllMimeRender '[] a where
--------------------------------------------------------------------------
-- Check that all elements of list are instances of MimeUnrender
--------------------------------------------------------------------------
class AllMimeUnrender (list :: [*]) a where
class (AllMime list) => AllMimeUnrender (list :: [*]) a where
allMimeUnrender :: Proxy list
-> ByteString
-> [(M.MediaType, Either String a)]