@@ -1,24 +1,69 @@
11module Servant.QuickCheck.Internal.Predicates where
22
3−import Data.Monoid ((<>))
4−import GHC.Generics (Generic)
5−import Control.Monad
6−import Network.HTTP.Client (Request, Response, responseStatus)
7−import Network.HTTP.Types (status500)
8−import qualified Data.ByteString.Lazy as LBS
9−import Data.Text (Text)
10−
11−-- | @500 Internal Server Error@ should be avoided - it may represent some
3+import Control.Exception (catch, throw)
4+import Control.Monad (liftM2, unless, when)
5+import Data.Aeson (Object, decode)
6+import Data.Bifunctor (first)
7+import qualified Data.ByteString as SBS
8+import qualified Data.ByteString.Char8 as SBSC
9+import qualified Data.ByteString.Lazy as LBS
10+import Data.CaseInsensitive (foldCase, foldedCase, mk)
11+import Data.Either (isRight)
12+import Data.List.Split (wordsBy)
13+import Data.Maybe (fromMaybe, isJust)
14+import Data.Semigroup (Semigroup (..))
15+import qualified Data.Text as T
16+import Data.Time (UTCTime, defaultTimeLocale, parseTimeM,
17+ rfc822DateFormat)
18+import GHC.Generics (Generic)
19+import Network.HTTP.Client (Manager, Request, Response, httpLbs,
20+ method, parseRequest, requestHeaders,
21+ responseBody, responseHeaders,
22+ responseStatus)
23+import Network.HTTP.Media (matchAccept)
24+import Network.HTTP.Types (methodGet, methodHead, parseMethod,
25+ renderStdMethod, status100, status200,
26+ status201, status300, status401,
27+ status405, status500)
28+import Prelude.Compat
29+import System.Clock (Clock (Monotonic), diffTimeSpec,
30+ getTime, toNanoSecs)
31+
32+import Servant.QuickCheck.Internal.ErrorTypes
33+
34+
35+-- | [__Best Practice__]
36+--
37+-- @500 Internal Server Error@ should be avoided - it may represent some
1238-- issue with the application code, and it moreover gives the client little
1339-- indication of how to proceed or what went wrong.
1440--
1541-- This function checks that the response code is not 500.
16−not500 :: ResponsePredicate Text [Text]
17−not500 = ResponsePredicate "not500" (\resp ->
18− if responseStatus resp == status500 then ["not500"] else [])
42+--
43+-- /Since 0.0.0.0/
44+not500 :: ResponsePredicate
45+not500 = ResponsePredicate $ \resp ->
46+ when (responseStatus resp == status500) $ throw $ PredicateFailure "not500" Nothing resp
1947
20−{-
21−-- | Returning anything other than an object when returning JSON is considered
48+-- | [__Optional__]
49+--
50+-- This function checks that the response from the server does not take longer
51+-- than the specified number of nanoseconds.
52+--
53+-- /Since 0.0.2.1/
54+notLongerThan :: Integer -> RequestPredicate
55+notLongerThan maxAllowed
56+ = RequestPredicate $ \req mgr -> do
57+ start <- getTime Monotonic
58+ resp <- httpLbs req mgr
59+ end <- getTime Monotonic
60+ when (toNanoSecs (end `diffTimeSpec` start) > maxAllowed) $
61+ throw $ PredicateFailure "notLongerThan" (Just req) resp
62+ return []
63+
64+-- | [__Best Practice__]
65+--
66+-- Returning anything other than an object when returning JSON is considered
2267-- bad practice, as:
2368--
2469-- (1) it is hard to modify the returned value while maintaining backwards
@@ -30,64 +75,202 @@ not500 = ResponsePredicate "not500" (\resp ->
3075--
3176-- This function checks that any @application/json@ responses only return JSON
3277-- objects (and not arrays, strings, numbers, or booleans) at the top level.
33−onlyJsonObjects :: Response b -> IO Bool
78+--
79+-- __References__:
80+--
81+-- * JSON Grammar: <https://tools.ietf.org/html/rfc7159#section-2 RFC 7159 Section 2>
82+-- * JSON Grammar: <https://tools.ietf.org/html/rfc4627#section-2 RFC 4627 Section 2>
83+--
84+-- /Since 0.0.0.0/
85+onlyJsonObjects :: ResponsePredicate
3486onlyJsonObjects
35− = ResponsePredicate "onlyJsonObjects" _
87+ = ResponsePredicate (\resp -> do
88+ case lookup "content-type" (first foldedCase <$> responseHeaders resp) of
89+ Nothing -> return ()
90+ Just ctype -> when ("application/json" `SBS.isPrefixOf` ctype) $ do
91+ case (decode (responseBody resp) :: Maybe Object) of
92+ Nothing -> throw $ PredicateFailure "onlyJsonObjects" Nothing resp
93+ Just _ -> return ())
3694
37−-- | When creating a new resource, it is good practice to provide a @Location@
95+-- | __Optional__
96+--
97+-- When creating a new resource, it is good practice to provide a @Location@
3898-- header with a link to the created resource.
3999--
40100-- This function checks that every @201 Created@ response contains a @Location@
41101-- header, and that the link in it responds with a 2XX response code to @GET@
42102-- requests.
43103--
44−-- References: <RFC 7231, Section 6.3.2 https://tools.ietf.org/html/rfc7231#section-6.3.2>
45−createContainsValidLocation :: Response b -> IO Bool
104+-- This is considered optional because other means of linking to the resource
105+-- (e.g. via the response body) are also acceptable; linking to the resource in
106+-- some way is considered best practice.
107+--
108+-- __References__:
109+--
110+-- * 201 Created: <https://tools.ietf.org/html/rfc7231#section-6.3.2 RFC 7231 Section 6.3.2>
111+-- * Location header: <https://tools.ietf.org/html/rfc7231#section-7.1.2 RFC 7231 Section 7.1.2>
112+--
113+-- /Since 0.0.0.0/
114+createContainsValidLocation :: RequestPredicate
46115createContainsValidLocation
47− = ResponsePredicate "createContainsValidLocation" _
116+ = RequestPredicate $ \req mgr -> do
117+ let n = "createContainsValidLocation"
118+ resp <- httpLbs req mgr
119+ if responseStatus resp == status201
120+ then case lookup "Location" $ responseHeaders resp of
121+ Nothing -> throw $ PredicateFailure n (Just req) resp
122+ Just l -> case parseRequest $ SBSC.unpack l of
123+ Nothing -> throw $ PredicateFailure n (Just req) resp
124+ Just x -> do
125+ resp2 <- httpLbs x mgr
126+ status2XX (Just req) resp2 n
127+ return [resp, resp2]
128+ else return [resp]
48129
49−getsHaveLastModifiedHeader :: Response b -> IO Bool
130+-- | [__Optional__]
131+--
132+-- The @Last-Modified@ header represents the time a resource was last
133+-- modified. It is used to drive caching and conditional requests.
134+--
135+-- When using this mechanism, the server adds the @Last-Modified@ header to
136+-- responses. Clients may then make requests with the @If-Modified-Since@
137+-- header to conditionally request resources. If the resource has not
138+-- changed since that date, the server responds with a status code of 304
139+-- (@Not Modified@) without a response body.
140+--
141+-- The @Last-Modified@ header can also be used in conjunction with the
142+-- @If-Unmodified-Since@ header to drive optimistic concurrency.
143+--
144+-- The @Last-Modified@ date must be in RFC 822 format.
145+--
146+-- __References__:
147+--
148+-- * 304 Not Modified: <https://tools.ietf.org/html/rfc7232#section-4.1 RFC 7232 Section 4.1>
149+-- * Last-Modified header: <https://tools.ietf.org/html/rfc7232#section-2.2 RFC 7232 Section 2.2>
150+-- * If-Modified-Since header: <https://tools.ietf.org/html/rfc7232#section-3.3 RFC 7232 Section 3.3>
151+-- * If-Unmodified-Since header: <https://tools.ietf.org/html/rfc7232#section-3.4 RFC 7232 Section 3.4>
152+-- * Date format: <https://tools.ietf.org/html/rfc2616#section-3.3 RFC 2616 Section 3.3>
153+--
154+-- /Since 0.0.2.1/
155+getsHaveLastModifiedHeader :: RequestPredicate
50156getsHaveLastModifiedHeader
51− = ResponsePredicate "getsHaveLastModifiedHeader" _
157+ = RequestPredicate $ \req mgr ->
158+ if (method req == methodGet)
159+ then do
160+ resp <- httpLbs req mgr
161+ unless (hasValidHeader "Last-Modified" isRFC822Date resp) $ do
162+ throw $ PredicateFailure "getsHaveLastModifiedHeader" (Just req) resp
163+ return [resp]
164+ else return []
52165
53−-- | When an HTTP request has a method that is not allowed, a 405 response
54−-- should be returned. Additionally, it is good practice to return an @Allow@
166+
167+
168+-- | [__RFC Compliance__]
169+--
170+-- When an HTTP request has a method that is not allowed,
171+-- a 405 response should be returned. Additionally, it is good practice to
172+-- return an @Allow@
55173-- header with the list of allowed methods.
56174--
57175-- This function checks that every @405 Method Not Allowed@ response contains
58176-- an @Allow@ header with a list of standard HTTP methods.
59−notAllowedContainsAllowHeader :: Response b -> IO Bool
177+--
178+-- Note that 'servant' itself does not currently set the @Allow@ headers.
179+--
180+-- __References__:
181+--
182+-- * @Allow@ header: <https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html RFC 2616 Section 14.7>
183+-- * Status 405: <https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html RFC 2616 Section 10.4.6>
184+-- * Servant Allow header issue: <https://github.com/haskell-servant/servant/issues/489 Issue #489>
185+--
186+-- /Since 0.0.0.0/
187+notAllowedContainsAllowHeader :: RequestPredicate
60188notAllowedContainsAllowHeader
61− = ResponsePredicate "notAllowedContainsAllowHeader" _
189+ = RequestPredicate $ \req mgr -> do
190+ let reqs = [ req { method = renderStdMethod m } | m <- [minBound .. maxBound]
191+ , renderStdMethod m /= method req ]
192+ resp <- mapM (flip httpLbs mgr) reqs
193+
194+ case filter pred' (zip reqs resp) of
195+ (x:_) -> throw $ PredicateFailure "notAllowedContainsAllowHeader" (Just $ fst x) (snd x)
196+ [] -> return resp
197+ where
198+ pred' (_, resp) = responseStatus resp == status405 && not (hasValidHeader "Allow" go resp)
199+ where
200+ go x = all (\y -> isRight $ parseMethod $ SBSC.pack y)
201+ $ wordsBy (`elem` (", " :: [Char])) (SBSC.unpack x)
62202
63−-- | When a request contains an @Accept@ header, the server must either return
203+
204+-- | [__RFC Compliance__]
205+--
206+-- When a request contains an @Accept@ header, the server must either return
64207-- content in one of the requested representations, or respond with @406 Not
65208-- Acceptable@.
66209--
67210-- This function checks that every *successful* response has a @Content-Type@
68−-- header that matches the @Accept@ header.
69−honoursAcceptHeader :: Predicate b Bool
211+-- header that matches the @Accept@ header. It does *not* check that the server
212+-- matches the quality descriptions of the @Accept@ header correctly.
213+--
214+-- __References__:
215+--
216+-- * @Accept@ header: <https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html RFC 2616 Section 14.1>
217+--
218+-- /Since 0.0.0.0/
219+honoursAcceptHeader :: RequestPredicate
70220honoursAcceptHeader
71− = RequestPredicate "honoursAcceptHeader" _
221+ = RequestPredicate $ \req mgr -> do
222+ resp <- httpLbs req mgr
223+ let scode = responseStatus resp
224+ sctype = lookup "Content-Type" $ responseHeaders resp
225+ sacc = fromMaybe "*/*" $ lookup "Accept" (requestHeaders req)
226+ if status100 < scode && scode < status300
227+ then if isJust $ sctype >>= \x -> matchAccept [x] sacc
228+ then throw $ PredicateFailure "honoursAcceptHeader" (Just req) resp
229+ else return [resp]
230+ else return [resp]
231+
72232
73−-- | Whether or not a representation should be cached, it is good practice to
233+-- | [__Best Practice__]
234+--
235+-- Whether or not a representation should be cached, it is good practice to
74236-- have a @Cache-Control@ header for @GET@ requests. If the representation
75237-- should not be cached, used @Cache-Control: no-cache@.
76238--
77−-- This function checks that @GET@ responses have a valid @Cache-Control@
78−-- header.
239+-- This function checks that @GET@ responses have @Cache-Control@ header.
240+-- It does NOT currently check that the header is valid.
241+--
242+-- __References__:
243+--
244+-- * @Cache-Control@ header: <https://tools.ietf.org/html/rfc7234#section-5.2 RFC 7234 Section 5.2>
79245--
80−-- References: RFC 7234 Section 5.2
81−-- https://tools.ietf.org/html/rfc7234#section-5.2
82−getsHaveCacheControlHeader :: Predicate b Bool
246+-- /Since 0.0.0.0/
247+getsHaveCacheControlHeader :: RequestPredicate
83248getsHaveCacheControlHeader
84− = ResponsePredicate "getsHaveCacheControlHeader" _
249+ = RequestPredicate $ \req mgr ->
250+ if (method req == methodGet)
251+ then do
252+ resp <- httpLbs req mgr
253+ unless (hasValidHeader "Cache-Control" (const True) resp) $ do
254+ throw $ PredicateFailure "getsHaveCacheControlHeader" (Just req) resp
255+ return [resp]
256+ else return []
85257
86−-- | Like 'getsHaveCacheControlHeader', but for @HEAD@ requests.
87−headsHaveCacheControlHeader :: Predicate b Bool
258+-- | [__Best Practice__]
259+--
260+-- Like 'getsHaveCacheControlHeader', but for @HEAD@ requests.
261+--
262+-- /Since 0.0.0.0/
263+headsHaveCacheControlHeader :: RequestPredicate
88264headsHaveCacheControlHeader
89− = ResponsePredicate "headsHaveCacheControlHeader" _
90−
265+ = RequestPredicate $ \req mgr ->
266+ if (method req == methodHead)
267+ then do
268+ resp <- httpLbs req mgr
269+ unless (hasValidHeader "Cache-Control" (const True) resp) $
270+ throw $ PredicateFailure "headsHaveCacheControlHeader" (Just req) resp
271+ return [resp]
272+ else return []
273+{-
91274-- |
92275--
93276-- If the original request modifies the resource, this function makes two
@@ -128,23 +311,56 @@ optionsContainsValidAllow
128311-- This function checks that any @Link@ headers have values in the correct
129312-- format.
130313--
131−-- References: RFC 5988 Section 5
132−-- https://tools.ietf.org/html/rfc5988
314+-- __References__:
315+--
316+-- * <https://tools.ietf.org/html/rfc5988 RFC 5988 Section 5>
133317linkHeadersAreValid :: Predicate b Bool
134318linkHeadersAreValid
135319 = ResponsePredicate "linkHeadersAreValid" _
136320
137−-- | Any @401 Unauthorized@ response must include a @WWW-Authenticate@ header.
321+-}
322+-- | [__RFC Compliance__]
323+--
324+-- Any @401 Unauthorized@ response must include a @WWW-Authenticate@ header.
138325--
139326-- This function checks that, if a response has status code 401, it contains a
140327-- @WWW-Authenticate@ header.
141328--
142−-- References: RFC 7235 Section 4.1
143−-- https://tools.ietf.org/html/rfc7235#section-4.1
144−unauthorizedContainsWWWAuthenticate :: Predicate b Bool
329+-- __References__:
330+--
331+-- * @WWW-Authenticate@ header: <https://tools.ietf.org/html/rfc7235#section-4.1 RFC 7235 Section 4.1>
332+--
333+-- /Since 0.0.0.0/
334+unauthorizedContainsWWWAuthenticate :: ResponsePredicate
145335unauthorizedContainsWWWAuthenticate
146− = ResponsePredicate "unauthorizedContainsWWWAuthenticate" _
147−-}
336+ = ResponsePredicate $ \resp ->
337+ if responseStatus resp == status401
338+ then unless (hasValidHeader "WWW-Authenticate" (const True) resp) $
339+ throw $ PredicateFailure "unauthorizedContainsWWWAuthenticate" Nothing resp
340+ else return ()
341+
342+
343+-- | [__RFC Compliance__]
344+--
345+-- [An HTML] document will start with exactly this string: <!DOCTYPE html>
346+--
347+-- This function checks that HTML documents (those with `Content-Type: text/html...`)
348+-- include a DOCTYPE declaration at the top. We do not enforce capital case for the string `DOCTYPE`.
349+--
350+-- __References__:
351+--
352+-- * HTML5 Doctype: <https://tools.ietf.org/html/rfc7992#section-6.1 RFC 7992 Section 6.1>
353+-- /Since 0.3.0.0/
354+htmlIncludesDoctype :: ResponsePredicate
355+htmlIncludesDoctype
356+ = ResponsePredicate $ \resp ->
357+ if hasValidHeader "Content-Type" (SBS.isPrefixOf . foldCase $ "text/html") resp
358+ then do
359+ let htmlContent = foldCase . LBS.take 20 $ responseBody resp
360+ unless (LBS.isPrefixOf (foldCase "<!doctype html>") htmlContent) $
361+ throw $ PredicateFailure "htmlIncludesDoctype" Nothing resp
362+ else return ()
363+
148364-- * Predicate logic
149365
150366-- The idea with all this footwork is to not waste any requests. Rather than
@@ -153,58 +369,93 @@ unauthorizedContainsWWWAuthenticate
153369--
154370-- Still, this is all kind of ugly.
155371
156−data ResponsePredicate n r = ResponsePredicate
157− { respPredName :: n
158− , respPred :: Response LBS.ByteString -> r
159− } deriving (Functor, Generic)
160−
161−instance (Monoid n, Monoid r) => Monoid (ResponsePredicate n r) where
162− mempty = ResponsePredicate mempty mempty
163− a `mappend` b = ResponsePredicate
164− { respPredName = respPredName a <> respPredName b
165− , respPred = respPred a <> respPred b
166− }
167−
168−data RequestPredicate n r = RequestPredicate
169− { reqPredName :: n
170− , reqResps :: Request -> IO [Response LBS.ByteString]
171− , reqPred :: ResponsePredicate n r
172− } deriving (Generic, Functor)
173−
174−instance (Monoid n, Monoid r) => Monoid (RequestPredicate n r) where
175− mempty = RequestPredicate mempty (\_ -> return mempty) mempty
176− a `mappend` b = RequestPredicate
177− { reqPredName = reqPredName a <> reqPredName b
178− , reqResps = \x -> liftM2 (<>) (reqResps a x) (reqResps b x)
179− , reqPred = reqPred a <> reqPred b
180− }
181−
182−data Predicates n r = Predicates
183− { reqPreds :: RequestPredicate n r
184− , respPreds :: ResponsePredicate n r
185− } deriving (Generic, Functor)
186−
187−instance (Monoid n, Monoid r) => Monoid (Predicates n r) where
188− mempty = Predicates mempty mempty
189− a `mappend` b = Predicates (reqPreds a <> reqPreds b) (respPreds a <> respPreds b)
372+-- | A predicate that depends only on the response.
373+--
374+-- /Since 0.0.0.0/
375+newtype ResponsePredicate = ResponsePredicate
376+ { getResponsePredicate :: Response LBS.ByteString -> IO ()
377+ } deriving (Generic)
378+
379+instance Semigroup ResponsePredicate where
380+ ResponsePredicate a <> ResponsePredicate b = ResponsePredicate $ \x -> a x >> b x
381+
382+instance Monoid ResponsePredicate where
383+ mempty = ResponsePredicate $ const $ return ()
384+ mappend = (<>)
190385
386+-- | A predicate that depends on both the request and the response.
387+--
388+-- /Since 0.0.0.0/
389+newtype RequestPredicate = RequestPredicate
390+ { getRequestPredicate :: Request -> Manager -> IO [Response LBS.ByteString]
391+ } deriving (Generic)
392+
393+-- TODO: This isn't actually a monoid
394+instance Monoid RequestPredicate where
395+ mempty = RequestPredicate (\r m -> httpLbs r m >>= \x -> return ([x]))
396+ mappend = (<>)
397+
398+-- TODO: This isn't actually a monoid
399+instance Semigroup RequestPredicate where
400+ RequestPredicate a <> RequestPredicate b = RequestPredicate $ \r mgr ->
401+ liftM2 (<>) (a r mgr) (b r mgr)
191402
403+-- | A set of predicates. Construct one with 'mempty' and '<%>'.
404+data Predicates = Predicates
405+ { requestPredicates :: RequestPredicate
406+ , responsePredicates :: ResponsePredicate
407+ } deriving (Generic)
408+
409+instance Semigroup Predicates where
410+ a <> b = Predicates (requestPredicates a <> requestPredicates b)
411+ (responsePredicates a <> responsePredicates b)
412+
413+instance Monoid Predicates where
414+ mempty = Predicates mempty mempty
415+ mappend = (<>)
192416
193417class JoinPreds a where
194− joinPreds :: a -> Predicates [Text] [Text] -> Predicates [Text] [Text]
418+ joinPreds :: a -> Predicates -> Predicates
195419
196−instance JoinPreds (RequestPredicate Text Bool) where
420+instance JoinPreds (RequestPredicate ) where
197421 joinPreds p (Predicates x y) = Predicates (p <> x) y
198422
199−instance JoinPreds (ResponsePredicate Text Bool) where
423+instance JoinPreds (ResponsePredicate ) where
200424 joinPreds p (Predicates x y) = Predicates x (p <> y)
201425
202−infixr 6 <%>
203−(<%>) :: JoinPreds a n b r => a -> Predicates n b r -> Predicates n b r
426+-- | Adds a new predicate (either `ResponsePredicate` or `RequestPredicate`) to
427+-- the existing predicates.
428+--
429+-- > not500 <%> onlyJsonObjects <%> empty
430+--
431+-- /Since 0.0.0.0/
432+(<%>) :: JoinPreds a => a -> Predicates -> Predicates
204433(<%>) = joinPreds
434+infixr 6 <%>
435+
436+finishPredicates :: Predicates -> Request -> Manager -> IO (Maybe PredicateFailure)
437+finishPredicates p req mgr = go `catch` \(e :: PredicateFailure) -> return $ Just e
438+ where
439+ go = do
440+ resps <- getRequestPredicate (requestPredicates p) req mgr
441+ mapM_ (getResponsePredicate $ responsePredicates p) resps
442+ return Nothing
443+
444+-- * helpers
445+
446+hasValidHeader :: SBS.ByteString -> (SBS.ByteString -> Bool) -> Response b -> Bool
447+hasValidHeader hdr p r = case lookup (mk hdr) (responseHeaders r) of
448+ Nothing -> False
449+ Just v -> p v
450+
451+isRFC822Date :: SBS.ByteString -> Bool
452+isRFC822Date s
453+ = case parseTimeM True defaultTimeLocale rfc822DateFormat (SBSC.unpack s) of
454+ Nothing -> False
455+ Just (_ :: UTCTime) -> True
205456
206−finishPredicates :: Predicates [Text] [Text] -> Request -> IO [Text]
207−finishPredicates p req = do
208− resps <- reqResps (reqPreds p) req
209− let preds = reqPred (reqPreds p) <> respPreds p
210− return $ mconcat [respPred preds r | r <- resps ]
457+status2XX :: Monad m => Maybe Request -> Response LBS.ByteString -> T.Text -> m ()
458+status2XX mreq resp t
459+ | status200 <= responseStatus resp && responseStatus resp < status300
460+ = return ()
461+ | otherwise = throw $ PredicateFailure t mreq resp