diff --git a/ChangeLog.md b/ChangeLog.md new file mode 100644 --- /dev/null +++ b/ChangeLog.md @@ -0,0 +1,69 @@ +# ChangeLog for wai + +## 3.2.4 + +* Add helpers for modifying request headers: `modifyRequest` and `mapRequestHeaders`. [#710](https://github.com/yesodweb/wai/pull/710) [#952](https://github.com/yesodweb/wai/pull/952) +* Small documentation adjustments like adding more `@since` markers. [#952](https://github.com/yesodweb/wai/pull/952) +* Add `setRequestBodyChunks` to mirror `getRequestBodyChunk` and avoid deprecation warnings when using `requestBody` as a setter. [#949](https://github.com/yesodweb/wai/pull/949) +* Overhaul documentation of `Middleware`. [#858](https://github.com/yesodweb/wai/pull/858) + +## 3.2.3 + +* Add documentation recommending streaming request bodies. [#818](https://github.com/yesodweb/wai/pull/818) +* Add two functions, `consumeRequestBodyStrict` and `consumeRequestBodyLazy`, + that are synonyms for `strictRequestBody` and `lazyRequestBody`. [#818](https://github.com/yesodweb/wai/pull/818) + +## 3.2.2.1 + +* Fix missing reexport of `getRequestBodyChunk` [#753](https://github.com/yesodweb/wai/issues/753) + +## 3.2.2 + +* Deprecate `requestBody` in favor of the more clearly named `getRequestBodyChunk`. [#726](https://github.com/yesodweb/wai/pull/726) + +## 3.2.1.2 + +* Remove dependency on blaze-builder [#683](https://github.com/yesodweb/wai/pull/683) + +## 3.2.1.1 + +* Relax upper bound on bytestring-builder + +## 3.2.1 + +* add mapResponseStatus [#532](https://github.com/yesodweb/wai/pull/532) + +## 3.2.0.1 + +* Add missing changelog entry + +## 3.2.0 + +* Major version up due to breaking changes. We chose 3.2.0, not 3.1.0 + for consistency with Warp 3.2.0. +* The `Network.Wai.HTTP2` module was removed. +* `tryGetFileSize`, `hContentRange`, `hAcceptRanges`, `contentRangeHeader` and + `chooseFilePart`, `adjustForFilePart` and `parseByteRanges` were removed + from the `Network.Wai.Internal` module. +* New fields for `Request`: `requestHeaderReferer` and `requestHeaderUserAgent`. + +## 3.0.5.0 + +* Avoid using the `IsString` Builder instance + +## 3.0.4.0 + +* A new module `Network.Wai.HTTP2` is exported. + +## 3.0.3.0 + +* `mapResponseHeaders`, `ifRequest` and `modifyResponse` are exported. + +## 3.0.2.3 + +* Allow blaze-builder 0.4 + +## 3.0.2.2 + +* Clarify some documentation on `rawPathInfo`. [Relevant Github + discussion](https://github.com/yesodweb/wai/issues/325#issuecomment-69896780). diff --git a/LICENSE b/LICENSE --- a/LICENSE +++ b/LICENSE @@ -1,25 +1,20 @@ -The following license covers this documentation, and the source code, except -where otherwise indicated. - -Copyright 2010, Michael Snoyman. All rights reserved. - -Redistribution and use in source and binary forms, with or without -modification, are permitted provided that the following conditions are met: +Copyright (c) 2012 Michael Snoyman, http://www.yesodweb.com/ -* Redistributions of source code must retain the above copyright notice, this - list of conditions and the following disclaimer. +Permission is hereby granted, free of charge, to any person obtaining +a copy of this software and associated documentation files (the +"Software"), to deal in the Software without restriction, including +without limitation the rights to use, copy, modify, merge, publish, +distribute, sublicense, and/or sell copies of the Software, and to +permit persons to whom the Software is furnished to do so, subject to +the following conditions: -* Redistributions in binary form must reproduce the above copyright notice, - this list of conditions and the following disclaimer in the documentation - and/or other materials provided with the distribution. +The above copyright notice and this permission notice shall be +included in all copies or substantial portions of the Software. -THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS "AS IS" AND ANY EXPRESS OR -IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF -MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO -EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY DIRECT, INDIRECT, -INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT -NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, -OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF -LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE -OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF -ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, +EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF +MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND +NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE +LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION +OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION +WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. diff --git a/Network/Wai.hs b/Network/Wai.hs --- a/Network/Wai.hs +++ b/Network/Wai.hs @@ -1,16 +1,14 @@ -{-# LANGUAGE Rank2Types #-} -{-# LANGUAGE ExistentialQuantification #-} -{-# LANGUAGE DeriveDataTypeable #-} {-| This module defines a generic web application interface. It is a common protocol between web servers and web applications. -The overriding design principles here are performance and generality . To -address performance, this library is built on top of the enumerator and -blaze-builder packages. The advantages of enumerators over lazy IO have been -debated elsewhere and so will not be addressed here. However, helper functions -like 'responseLBS' allow you to continue using lazy IO if you so desire. +The overriding design principles here are performance and generality. To +address performance, this library uses a streaming interface for request and +response bodies, paired with bytestring's 'Builder' type. The advantages of a +streaming API over lazy IO have been debated elsewhere and so will not be +addressed here. However, helper functions like 'responseLBS' allow you to +continue using lazy IO if you so desire. Generality is achieved by removing many variables commonly found in similar projects that are not universal to all servers. The goal is that the 'Request' @@ -32,78 +30,91 @@ [wai-extra] -[wai-test] - -} +-- Ignore deprecations, because this module needs to use the deprecated requestBody to construct a response. +{-# OPTIONS_GHC -fno-warn-deprecations #-} module Network.Wai - ( -- * WAI interface - Request (..) - , Response (..) - , responseSource - , Application + ( + -- * Types + Application , Middleware + , ResponseReceived + -- * Request + , Request + , defaultRequest + , RequestBodyLength (..) + -- ** Request accessors + , requestMethod + , httpVersion + , rawPathInfo + , rawQueryString + , requestHeaders + , isSecure + , remoteHost + , pathInfo + , queryString + , getRequestBodyChunk + , requestBody + , vault + , requestBodyLength + , requestHeaderHost + , requestHeaderRange + , requestHeaderReferer + , requestHeaderUserAgent + -- $streamingRequestBodies + , strictRequestBody + , consumeRequestBodyStrict + , lazyRequestBody + , consumeRequestBodyLazy + -- ** Request modifiers + , setRequestBodyChunks + , mapRequestHeaders + -- * Response + , Response + , StreamingBody , FilePart (..) - -- * Response body smart constructors + -- ** Response composers + , responseFile + , responseBuilder , responseLBS + , responseStream + , responseRaw + -- ** Response accessors , responseStatus + , responseHeaders + -- ** Response modifiers + , responseToStream + , mapResponseHeaders + , mapResponseStatus + -- * Middleware composition + , ifRequest + , modifyRequest + , modifyResponse ) where -import qualified Data.ByteString as B -import qualified Data.ByteString.Lazy as L -import Data.Typeable (Typeable) -import Control.Monad.Trans.Resource (ResourceT) -import qualified Data.Conduit as C -import qualified Data.Conduit.List as CL -import qualified Data.Conduit.Binary as CB -import Blaze.ByteString.Builder (Builder, fromLazyByteString) -import Network.Socket (SockAddr) -import qualified Network.HTTP.Types as H -import Data.Text (Text) -import Data.ByteString.Lazy.Char8 () -- makes it easier to use responseLBS -import Blaze.ByteString.Builder (fromByteString) -import Data.Vault (Vault) +import Data.ByteString.Builder (Builder, byteString, lazyByteString) +import Control.Monad (unless) +import qualified Data.ByteString as B +import qualified Data.ByteString.Lazy as L +import qualified Data.ByteString.Lazy.Internal as LI +import Data.ByteString.Lazy.Internal (defaultChunkSize) +import Data.Function (fix) +import qualified Network.HTTP.Types as H +import Network.Socket (SockAddr (SockAddrInet)) +import Network.Wai.Internal +import qualified System.IO as IO +import System.IO.Unsafe (unsafeInterleaveIO) --- | Information on the request sent by the client. This abstracts away the --- details of the underlying implementation. -data Request = Request - { requestMethod :: H.Method - , httpVersion :: H.HttpVersion - -- | Extra path information sent by the client. The meaning varies slightly - -- depending on backend; in a standalone server setting, this is most likely - -- all information after the domain name. In a CGI application, this would be - -- the information following the path to the CGI executable itself. - -- Do not modify this raw value- modify pathInfo instead. - , rawPathInfo :: B.ByteString - -- | If no query string was specified, this should be empty. This value - -- /will/ include the leading question mark. - -- Do not modify this raw value- modify queryString instead. - , rawQueryString :: B.ByteString - -- | Generally the host requested by the user via the Host request header. - -- Backends are free to provide alternative values as necessary. This value - -- should not be used to construct URLs. - , serverName :: B.ByteString - -- | The listening port that the server received this request on. It is - -- possible for a server to listen on a non-numeric port (i.e., Unix named - -- socket), in which case this value will be arbitrary. Like 'serverName', - -- this value should not be used in URL construction. - , serverPort :: Int - , requestHeaders :: H.RequestHeaders - -- | Was this request made over an SSL connection? - , isSecure :: Bool - -- | The client\'s host information. - , remoteHost :: SockAddr - -- | Path info in individual pieces- the url without a hostname/port and without a query string, split on forward slashes, - , pathInfo :: [Text] - -- | Parsed query string information - , queryString :: H.Query - , requestBody :: C.Source IO B.ByteString - -- | A location for arbitrary data to be shared by applications and middleware. - , vault :: Vault - } - deriving (Typeable) +---------------------------------------------------------------- --- | +-- | Creating 'Response' from a file. -- +-- @since 2.0.0 +responseFile :: H.Status -> H.ResponseHeaders -> FilePath -> Maybe FilePart -> Response +responseFile = ResponseFile + +-- | Creating 'Response' from 'Builder'. +-- -- Some questions and answers about the usage of 'Builder' here: -- -- Q1. Shouldn't it be at the user's discretion to use Builders internally and @@ -117,62 +128,453 @@ -- -- A2. No. If the ByteStrings are small, then they will be copied into a larger -- buffer, which should be a performance gain overall (less system calls). If --- they are already large, then blaze-builder uses an InsertByteString --- instruction to avoid copying. +-- they are already large, then an insert operation is used +-- to avoid copying. -- -- Q3. Doesn't this prevent us from creating comet-style servers, since data -- will be cached? -- --- A3. You can force blaze-builder to output a ByteString before it is an +-- A3. You can force a Builder to output a ByteString before it is an -- optimal size by sending a flush command. -data Response - = ResponseFile H.Status H.ResponseHeaders FilePath (Maybe FilePart) - | ResponseBuilder H.Status H.ResponseHeaders Builder - | ResponseSource H.Status H.ResponseHeaders (C.Source IO (C.Flush Builder)) - deriving Typeable +-- +-- @since 2.0.0 +responseBuilder :: H.Status -> H.ResponseHeaders -> Builder -> Response +responseBuilder = ResponseBuilder +-- | Creating 'Response' from 'L.ByteString'. This is a wrapper for +-- 'responseBuilder'. +-- +-- @since 0.3.0 +responseLBS :: H.Status -> H.ResponseHeaders -> L.ByteString -> Response +responseLBS s h = ResponseBuilder s h . lazyByteString + +-- | Creating 'Response' from a stream of values. +-- +-- In order to allocate resources in an exception-safe manner, you can use the +-- @bracket@ pattern outside of the call to @responseStream@. As a trivial +-- example: +-- +-- @ +-- app :: Application +-- app req respond = bracket_ +-- (putStrLn \"Allocating scarce resource\") +-- (putStrLn \"Cleaning up\") +-- $ respond $ responseStream status200 [] $ \\write flush -> do +-- write $ byteString \"Hello\\n\" +-- flush +-- write $ byteString \"World\\n\" +-- @ +-- +-- Note that in some cases you can use @bracket@ from inside @responseStream@ +-- as well. However, placing the call on the outside allows your status value +-- and response headers to depend on the scarce resource. +-- +-- @since 3.0.0 +responseStream :: H.Status + -> H.ResponseHeaders + -> StreamingBody + -> Response +responseStream = ResponseStream + +-- | Create a response for a raw application. This is useful for \"upgrade\" +-- situations such as WebSockets, where an application requests for the server +-- to grant it raw network access. +-- +-- This function requires a backup response to be provided, for the case where +-- the handler in question does not support such upgrading (e.g., CGI apps). +-- +-- In the event that you read from the request body before returning a +-- @responseRaw@, behavior is undefined. +-- +-- @since 2.1.0 +responseRaw :: (IO B.ByteString -> (B.ByteString -> IO ()) -> IO ()) + -> Response + -> Response +responseRaw = ResponseRaw + +---------------------------------------------------------------- + +-- | Accessing 'H.Status' in 'Response'. +-- +-- @since 1.2.0 responseStatus :: Response -> H.Status -responseStatus rsp = - case rsp of - ResponseFile s _ _ _ -> s - ResponseBuilder s _ _ -> s - ResponseSource s _ _ -> s +responseStatus (ResponseFile s _ _ _) = s +responseStatus (ResponseBuilder s _ _ ) = s +responseStatus (ResponseStream s _ _ ) = s +responseStatus (ResponseRaw _ res ) = responseStatus res -data FilePart = FilePart - { filePartOffset :: Integer - , filePartByteCount :: Integer - } deriving Show +-- | Accessing 'H.ResponseHeaders' in 'Response'. +-- +-- @since 2.0.0 +responseHeaders :: Response -> H.ResponseHeaders +responseHeaders (ResponseFile _ hs _ _) = hs +responseHeaders (ResponseBuilder _ hs _ ) = hs +responseHeaders (ResponseStream _ hs _ ) = hs +responseHeaders (ResponseRaw _ res) = responseHeaders res -responseSource :: Response -> (H.Status, H.ResponseHeaders, C.Source IO (C.Flush Builder)) -responseSource (ResponseSource s h b) = (s, h, b) -responseSource (ResponseFile s h fp (Just part)) = - (s, h, sourceFilePart part fp C.$= CL.map (C.Chunk . fromByteString)) -responseSource (ResponseFile s h fp Nothing) = - (s, h, CB.sourceFile fp C.$= CL.map (C.Chunk . fromByteString)) -responseSource (ResponseBuilder s h b) = - (s, h, CL.sourceList [C.Chunk b]) +-- | Converting the body information in 'Response' to a 'StreamingBody'. +-- +-- @since 3.0.0 +responseToStream :: Response + -> ( H.Status + , H.ResponseHeaders + , (StreamingBody -> IO a) -> IO a + ) +responseToStream (ResponseStream s h b) = (s, h, ($ b)) +responseToStream (ResponseFile s h fp (Just part)) = + ( s + , h + , \withBody -> IO.withBinaryFile fp IO.ReadMode $ \handle -> withBody $ \sendChunk _flush -> do + IO.hSeek handle IO.AbsoluteSeek $ filePartOffset part + let loop remaining | remaining <= 0 = return () + loop remaining = do + bs <- B.hGetSome handle defaultChunkSize + unless (B.null bs) $ do + let x = B.take remaining bs + sendChunk $ byteString x + loop $ remaining - B.length x + loop $ fromIntegral $ filePartByteCount part + ) +responseToStream (ResponseFile s h fp Nothing) = + ( s + , h + , \withBody -> IO.withBinaryFile fp IO.ReadMode $ \handle -> + withBody $ \sendChunk _flush -> fix $ \loop -> do + bs <- B.hGetSome handle defaultChunkSize + unless (B.null bs) $ do + sendChunk $ byteString bs + loop + ) +responseToStream (ResponseBuilder s h b) = + (s, h, \withBody -> withBody $ \sendChunk _flush -> sendChunk b) +responseToStream (ResponseRaw _ res) = responseToStream res -sourceFilePart :: FilePart -> FilePath -> C.Source IO B.ByteString -sourceFilePart (FilePart offset count) fp = - CB.sourceFileRange fp (Just offset) (Just count) +-- | Apply the provided function to the response header list of the Response. +-- +-- @since 3.0.3.0 +mapResponseHeaders :: (H.ResponseHeaders -> H.ResponseHeaders) -> Response -> Response +mapResponseHeaders f (ResponseFile s h b1 b2) = ResponseFile s (f h) b1 b2 +mapResponseHeaders f (ResponseBuilder s h b) = ResponseBuilder s (f h) b +mapResponseHeaders f (ResponseStream s h b) = ResponseStream s (f h) b +mapResponseHeaders _ r@(ResponseRaw _ _) = r -responseLBS :: H.Status -> H.ResponseHeaders -> L.ByteString -> Response -responseLBS s h = ResponseBuilder s h . fromLazyByteString +-- | Apply the provided function to the response status of the Response. +-- +-- @since 3.2.1 +mapResponseStatus :: (H.Status -> H.Status) -> Response -> Response +mapResponseStatus f (ResponseFile s h b1 b2) = ResponseFile (f s) h b1 b2 +mapResponseStatus f (ResponseBuilder s h b) = ResponseBuilder (f s) h b +mapResponseStatus f (ResponseStream s h b) = ResponseStream (f s) h b +mapResponseStatus _ r@(ResponseRaw _ _) = r -type Application = Request -> ResourceT IO Response +---------------------------------------------------------------- --- | Middleware is a component that sits between the server and application. It --- can do such tasks as GZIP encoding or response caching. What follows is the --- general definition of middleware, though a middleware author should feel --- free to modify this. +-- | The WAI application. -- --- As an example of an alternate type for middleware, suppose you write a --- function to load up session information. The session information is simply a --- string map \[(String, String)\]. A logical type signatures for this middleware --- might be: +-- Note that, since WAI 3.0, this type is structured in continuation passing +-- style to allow for proper safe resource handling. This was handled in the +-- past via other means (e.g., @ResourceT@). As a demonstration: -- --- @ loadSession :: ([(String, String)] -> Application) -> Application @ +-- @ +-- app :: Application +-- app req respond = bracket_ +-- (putStrLn \"Allocating scarce resource\") +-- (putStrLn \"Cleaning up\") +-- (respond $ responseLBS status200 [] \"Hello World\") +-- @ +type Application = Request -> (Response -> IO ResponseReceived) -> IO ResponseReceived + + +-- | A default, blank request. -- --- Here, instead of taking a standard 'Application' as its first argument, the --- middleware takes a function which consumes the session information as well. +-- @since 2.0.0 +defaultRequest :: Request +defaultRequest = Request + { requestMethod = H.methodGet + , httpVersion = H.http10 + , rawPathInfo = B.empty + , rawQueryString = B.empty + , requestHeaders = [] + , isSecure = False + , remoteHost = SockAddrInet 0 0 + , pathInfo = [] + , queryString = [] + , requestBody = return B.empty + , vault = mempty + , requestBodyLength = KnownLength 0 + , requestHeaderHost = Nothing + , requestHeaderRange = Nothing + , requestHeaderReferer = Nothing + , requestHeaderUserAgent = Nothing + } + + +-- | A @Middleware@ is a component that sits between the server and application. +-- +-- It can modify both the 'Request' and 'Response', +-- to provide simple transformations that are required for all (or most of) +-- your web server’s routes. +-- +-- = Users of middleware +-- +-- If you are trying to apply one or more 'Middleware's to your 'Application', +-- just call them as functions. +-- +-- For example, if you have @corsMiddleware@ and @authorizationMiddleware@, +-- and you want to authorize first, you can do: +-- +-- @ +-- let allMiddleware app = authorizationMiddleware (corsMiddleware app) +-- @ +-- +-- to get a new 'Middleware', which first authorizes, then sets, CORS headers. +-- The “outer” middleware is called first. +-- +-- You can also chain them via '(.)': +-- +-- @ +-- let allMiddleware = +-- authorizationMiddleware +-- . corsMiddleware +-- . … more middleware here … +-- @ +-- +-- Then, once you have an @app :: Application@, you can wrap it +-- in your middleware: +-- +-- @ +-- let myApp = allMiddleware app :: Application +-- @ +-- +-- and run it as usual: +-- +-- @ +-- Warp.run port myApp +-- @ +-- +-- = Authors of middleware +-- +-- When fully expanded, 'Middleware' has the type signature: +-- +-- > (Request -> (Response -> IO ResponseReceived) -> IO ResponseReceived) -> Request -> (Response -> IO ResponseReceived) -> IO ResponseReceived +-- +-- or if we shorten to @type Respond = Response -> IO ResponseReceived@: +-- +-- > (Request -> Respond -> IO ResponseReceived) -> Request -> Respond -> IO ResponseReceived +-- +-- so a middleware definition takes 3 arguments, an inner application, a request and a response callback. +-- +-- Compare with the type of a simple `Application`: +-- +-- > Request -> Respond -> IO ResponseReceived +-- +-- It takes the 'Request' and @Respond@, but not the extra application. +-- +-- Said differently, a middleware has the power of a normal 'Application' +-- — it can inspect the 'Request' and return a 'Response' — +-- but it can (and in many cases it /should/) also call the 'Application' which was passed to it. +-- +-- == Modifying the 'Request' +-- +-- A lot of middleware just looks at the request and does something based on its values. +-- +-- For example, the @authorizationMiddleware@ from above could look at the @Authorization@ +-- HTTP header and run verification logic against the database. +-- +-- @ +-- authorizationMiddleware app req respond = do +-- case verifyJWT ('requestHeaders' req) of +-- InvalidJWT err -> respond (invalidJWTResponse err) +-- ValidJWT -> app req respond +-- @ +-- +-- Notice how the inner app is called when the validation was successful. +-- If it was not, we can respond +-- e.g. with , +-- by constructing a 'Response' with 'responseLBS' and passing it to @respond@. +-- +-- == Passing arguments to and from your 'Middleware' +-- +-- Middleware must often be configurable. +-- Let’s say you have a type @JWTSettings@ that you want to be passed to the middleware. +-- Simply pass an extra argument to your middleware. Then your middleware type turns into: +-- +-- @ +-- authorizationMiddleware :: JWTSettings -> Application -> Request -> Respond -> IO ResponseReceived +-- authorizationMiddleware jwtSettings req respond = +-- case verifyJWT jwtSettings ('requestHeaders' req) of +-- InvalidJWT err -> respond (invalidJWTResponse err) +-- ValidJWT -> app req respond +-- @ +-- +-- or alternatively: +-- +-- @ +-- authorizationMiddleware :: JWTSettings -> Middleware +-- @ +-- +-- Perhaps less intuitively, you can also /pass on/ data from middleware to the wrapped 'Application': +-- +-- @ +-- authorizationMiddleware :: JWTSettings -> (JWT -> Application) -> Request -> Respond -> IO ResponseReceived +-- authorizationMiddleware jwtSettings req respond = +-- case verifyJWT jwtSettings ('requestHeaders' req) of +-- InvalidJWT err -> respond (invalidJWTResponse err) +-- ValidJWT jwt -> app jwt req respond +-- @ +-- +-- although then, chaining different middleware has to take this extra argument into account: +-- +-- @ +-- let finalApp = +-- authorizationMiddleware +-- (\\jwt -> corsMiddleware +-- (… more middleware here … +-- (app jwt))) +-- @ +-- +-- == Modifying the 'Response' +-- +-- 'Middleware' can also modify the 'Response' that is returned by the inner application. +-- +-- This is done by taking the @respond@ callback, using it to define a new @respond'@, +-- and passing this new @respond'@ to the @app@: +-- +-- @ +-- gzipMiddleware app req respond = do +-- let respond' resp = do +-- resp' <- gzipResponseBody resp +-- respond resp' +-- app req respond' +-- @ +-- +-- However, modifying the response (especially the response body) is not trivial, +-- so in order to get a sense of how to do it (dealing with the type of 'responseToStream'), +-- it’s best to look at an example, for example . + type Middleware = Application -> Application + +-- | Apply a function that modifies a request as a 'Middleware' +-- +-- @since 3.2.4 +modifyRequest :: (Request -> Request) -> Middleware +modifyRequest f app = app . f + +-- | Apply a function that modifies a response as a 'Middleware' +-- +-- @since 3.0.3.0 +modifyResponse :: (Response -> Response) -> Middleware +modifyResponse f app req respond = app req $ respond . f + +-- | Conditionally apply a 'Middleware' +-- +-- @since 3.0.3.0 +ifRequest :: (Request -> Bool) -> Middleware -> Middleware +ifRequest rpred middle app req + | rpred req = middle app req + | otherwise = app req + +-- $streamingRequestBodies +-- +-- == Streaming Request Bodies +-- +-- WAI is designed for streaming in request bodies, which allows you to process them incrementally. +-- You can stream in the request body using functions like 'getRequestBodyChunk', +-- the @wai-conduit@ package, or Yesod's @rawRequestBody@. +-- +-- In the normal case, incremental processing is more efficient, since it +-- reduces maximum total memory usage. +-- In the worst case, it helps protect your server against denial-of-service (DOS) attacks, in which +-- an attacker sends huge request bodies to your server. +-- +-- Consider these tips to avoid reading the entire request body into memory: +-- +-- * Look for library functions that support incremental processing. Sometimes these will use streaming +-- libraries like @conduit@, @pipes@, or @streaming@. +-- * Any attoparsec parser supports streaming input. For an example of this, see the +-- "Data.Conduit.Attoparsec" module in @conduit-extra@. +-- * Consider streaming directly to a file on disk. For an example of this, see the +-- "Data.Conduit.Binary" module in @conduit-extra@. +-- * If you need to direct the request body to multiple destinations, you can stream to both those +-- destinations at the same time. +-- For example, if you wanted to run an HMAC on the request body as well as parse it into JSON, +-- you could use Conduit's @zipSinks@ to send the data to @cryptonite-conduit@'s 'sinkHMAC' and +-- @aeson@'s Attoparsec parser. +-- * If possible, avoid processing large data on your server at all. +-- For example, instead of uploading a file to your server and then to AWS S3, +-- you can have the browser upload directly to S3. +-- +-- That said, sometimes it is convenient, or even necessary to read the whole request body into memory. +-- For these purposes, functions like 'strictRequestBody' or 'lazyRequestBody' can be used. +-- When this is the case, consider these strategies to mitigating potential DOS attacks: +-- +-- * Set a limit on the request body size you allow. +-- If certain endpoints need larger bodies, whitelist just those endpoints for the large size. +-- Be especially cautious about endpoints that don't require authentication, since these are easier to DOS. +-- You can accomplish this with @wai-extra@'s @requestSizeLimitMiddleware@ or Yesod's @maximumContentLength@. +-- * Consider rate limiting not just on total requests, but also on total bytes sent in. +-- * Consider using services that allow you to identify and blacklist attackers. +-- * Minimize the amount of time the request body stays in memory. +-- * If you need to share request bodies across middleware and your application, you can do so using Wai's 'vault'. +-- If you do this, remove the request body from the vault as soon as possible. +-- +-- Warning: Incremental processing will not always be sufficient to prevent a DOS attack. +-- For example, if an attacker sends you a JSON body with a 2MB long string inside, +-- even if you process the body incrementally, you'll still end up with a 2MB-sized 'Text'. +-- +-- To mitigate this, employ some of the countermeasures listed above, +-- and try to reject such payloads as early as possible in your codebase. + +-- | Get the request body as a lazy ByteString. However, do /not/ use any lazy +-- I\/O, instead reading the entire body into memory strictly. +-- +-- Note: Since this function consumes the request body, future calls to it will return the empty string. +-- +-- @since 3.0.1 +strictRequestBody :: Request -> IO L.ByteString +strictRequestBody req = + loop id + where + loop front = do + bs <- getRequestBodyChunk req + if B.null bs + then return $ front LI.Empty + else loop (front . LI.Chunk bs) + +-- | Synonym for 'strictRequestBody'. +-- This function name is meant to signal the non-idempotent nature of 'strictRequestBody'. +-- +-- @since 3.2.3 +consumeRequestBodyStrict :: Request -> IO L.ByteString +consumeRequestBodyStrict = strictRequestBody + +-- | Get the request body as a lazy ByteString. This uses lazy I\/O under the +-- surface, and therefore all typical warnings regarding lazy I/O apply. +-- +-- Note: Since this function consumes the request body, future calls to it will return the empty string. +-- +-- @since 1.4.1 +lazyRequestBody :: Request -> IO L.ByteString +lazyRequestBody req = + loop + where + loop = unsafeInterleaveIO $ do + bs <- getRequestBodyChunk req + if B.null bs + then return LI.Empty + else do + bss <- loop + return $ LI.Chunk bs bss + +-- | Synonym for 'lazyRequestBody'. +-- This function name is meant to signal the non-idempotent nature of 'lazyRequestBody'. +-- +-- @since 3.2.3 +consumeRequestBodyLazy :: Request -> IO L.ByteString +consumeRequestBodyLazy = lazyRequestBody + +-- | Apply the provided function to the request header list of the 'Request'. +-- +-- @since 3.2.4 +mapRequestHeaders :: (H.RequestHeaders -> H.RequestHeaders) -> Request -> Request +mapRequestHeaders f request = request { requestHeaders = f (requestHeaders request) } diff --git a/Network/Wai/Internal.hs b/Network/Wai/Internal.hs new file mode 100644 --- /dev/null +++ b/Network/Wai/Internal.hs @@ -0,0 +1,173 @@ +{-# OPTIONS_HADDOCK not-home #-} +{-# LANGUAGE RecordWildCards #-} +-- | Internal constructors and helper functions. Note that no guarantees are +-- given for stability of these interfaces. +module Network.Wai.Internal where + +import Data.ByteString.Builder (Builder) +import qualified Data.ByteString as B +import Data.Text (Text) +import Data.Typeable (Typeable) +import Data.Vault.Lazy (Vault) +import Data.Word (Word64) +import qualified Network.HTTP.Types as H +import Network.Socket (SockAddr) +import Data.List (intercalate) + +-- | Information on the request sent by the client. This abstracts away the +-- details of the underlying implementation. +{-# DEPRECATED requestBody "requestBody's name is misleading because it only gets a partial chunk of the body. Use getRequestBodyChunk instead when getting the field, and setRequestBodyChunks when setting the field." #-} +data Request = Request { + -- | Request method such as GET. + requestMethod :: H.Method + -- | HTTP version such as 1.1. + , httpVersion :: H.HttpVersion + -- | Extra path information sent by the client. The meaning varies slightly + -- depending on backend; in a standalone server setting, this is most likely + -- all information after the domain name. In a CGI application, this would be + -- the information following the path to the CGI executable itself. + -- + -- Middlewares and routing tools should not modify this raw value, as it may + -- be used for such things as creating redirect destinations by applications. + -- Instead, if you are writing a middleware or routing framework, modify the + -- @pathInfo@ instead. This is the approach taken by systems like Yesod + -- subsites. + -- + -- /Note/: At the time of writing this documentation, there is at least one + -- system (@Network.Wai.UrlMap@ from @wai-extra@) that does not follow the + -- above recommendation. Therefore, it is recommended that you test the + -- behavior of your application when using @rawPathInfo@ and any form of + -- library that might modify the @Request@. + , rawPathInfo :: B.ByteString + -- | If no query string was specified, this should be empty. This value + -- /will/ include the leading question mark. + -- Do not modify this raw value - modify queryString instead. + , rawQueryString :: B.ByteString + -- | A list of headers (a pair of key and value) in an HTTP request. + , requestHeaders :: H.RequestHeaders + -- | Was this request made over an SSL connection? + -- + -- Note that this value will /not/ tell you if the client originally made + -- this request over SSL, but rather whether the current connection is SSL. + -- The distinction lies with reverse proxies. In many cases, the client will + -- connect to a load balancer over SSL, but connect to the WAI handler + -- without SSL. In such a case, 'isSecure' will be 'False', but from a user + -- perspective, there is a secure connection. + , isSecure :: Bool + -- | The client\'s host information. + , remoteHost :: SockAddr + -- | Path info in individual pieces - the URL without a hostname/port and + -- without a query string, split on forward slashes. + , pathInfo :: [Text] + -- | Parsed query string information. + , queryString :: H.Query + -- | Get the next chunk of the body. Returns 'B.empty' when the + -- body is fully consumed. Since 3.2.2, this is deprecated in favor of 'getRequestBodyChunk'. + , requestBody :: IO B.ByteString + -- | A location for arbitrary data to be shared by applications and middleware. + , vault :: Vault + -- | The size of the request body. In the case of a chunked request body, + -- this may be unknown. + -- + -- @since 1.4.0 + , requestBodyLength :: RequestBodyLength + -- | The value of the Host header in a HTTP request. + -- + -- @since 2.0.0 + , requestHeaderHost :: Maybe B.ByteString + -- | The value of the Range header in a HTTP request. + -- + -- @since 2.0.0 + , requestHeaderRange :: Maybe B.ByteString + -- | The value of the Referer header in a HTTP request. + -- + -- @since 3.2.0 + , requestHeaderReferer :: Maybe B.ByteString + -- | The value of the User-Agent header in a HTTP request. + -- + -- @since 3.2.0 + , requestHeaderUserAgent :: Maybe B.ByteString + } + deriving (Typeable) + +-- | Get the next chunk of the body. Returns 'B.empty' when the +-- body is fully consumed. +-- +-- @since 3.2.2 +getRequestBodyChunk :: Request -> IO B.ByteString +getRequestBodyChunk = requestBody + +-- | Set the 'requestBody' attribute on a request without triggering a +-- deprecation warning. +-- +-- The supplied IO action should return the next chunk of the body each time it +-- is called and 'B.empty' when it has been fully consumed. +-- +-- @since 3.2.4 +setRequestBodyChunks :: IO B.ByteString -> Request -> Request +setRequestBodyChunks requestBody r = + r {requestBody = requestBody} + +instance Show Request where + show Request{..} = "Request {" ++ intercalate ", " [a ++ " = " ++ b | (a,b) <- fields] ++ "}" + where + fields = + [("requestMethod",show requestMethod) + ,("httpVersion",show httpVersion) + ,("rawPathInfo",show rawPathInfo) + ,("rawQueryString",show rawQueryString) + ,("requestHeaders",show requestHeaders) + ,("isSecure",show isSecure) + ,("remoteHost",show remoteHost) + ,("pathInfo",show pathInfo) + ,("queryString",show queryString) + ,("requestBody","") + ,("vault","") + ,("requestBodyLength",show requestBodyLength) + ,("requestHeaderHost",show requestHeaderHost) + ,("requestHeaderRange",show requestHeaderRange) + ] + + +data Response + = ResponseFile H.Status H.ResponseHeaders FilePath (Maybe FilePart) + | ResponseBuilder H.Status H.ResponseHeaders Builder + | ResponseStream H.Status H.ResponseHeaders StreamingBody + | ResponseRaw (IO B.ByteString -> (B.ByteString -> IO ()) -> IO ()) Response + deriving Typeable + +-- | Represents a streaming HTTP response body. It's a function of two +-- parameters; the first parameter provides a means of sending another chunk of +-- data, and the second parameter provides a means of flushing the data to the +-- client. +-- +-- @since 3.0.0 +type StreamingBody = (Builder -> IO ()) -> IO () -> IO () + +-- | The size of the request body. In the case of chunked bodies, the size will +-- not be known. +-- +-- @since 1.4.0 +data RequestBodyLength = ChunkedBody | KnownLength Word64 deriving Show + +-- | Information on which part to be sent. +-- Sophisticated application handles Range (and If-Range) then +-- create 'FilePart'. +-- +-- @since 0.4.0 +data FilePart = FilePart + { filePartOffset :: Integer + , filePartByteCount :: Integer + , filePartFileSize :: Integer + } deriving Show + +-- | A special datatype to indicate that the WAI handler has received the +-- response. This is to avoid the need for Rank2Types in the definition of +-- Application. +-- +-- It is /highly/ advised that only WAI handlers import and use the data +-- constructor for this data type. +-- +-- @since 3.0.0 +data ResponseReceived = ResponseReceived + deriving Typeable diff --git a/README.md b/README.md new file mode 100644 --- /dev/null +++ b/README.md @@ -0,0 +1,116 @@ +WAI: Web Application Interface +============================== + +Getting started +--------------- + +You want a minimal example? Here it is! + +~~~ {.haskell} +{-# LANGUAGE OverloadedStrings #-} +import Network.Wai +import Network.HTTP.Types +import Network.Wai.Handler.Warp (run) + +app :: Application +app _ respond = do + putStrLn "I've done some IO here" + respond $ responseLBS + status200 + [("Content-Type", "text/plain")] + "Hello, Web!" + +main :: IO () +main = do + putStrLn $ "http://localhost:8080/" + run 8080 app +~~~ + +Put that code into a file named _hello.hs_ and install [wai] and [warp] from Hackage: + + cabal install wai warp + +Run it: + + runhaskell hello.hs + +Point your browser to: + + http://localhost:8080/ + + +Serving static content +---------------------- + +We can modify our previous example to serve static content. For this create a file named _index.html_: + +

Hello, Web!

+ +Now we redefine `responseBody` to refer to that file: + +~~~ {.haskell} +app2 :: Application +app2 _ respond = respond index + +index :: Response +index = responseFile + status200 + [("Content-Type", "text/html")] + "index.html" + Nothing +~~~ + + +Basic dispatching +----------------- + +An `Application` maps `Request`s to `Response`s: + + ghci> :info Application + type Application = Request -> (Response -> IO ResponseReceived) -> IO ResponseReceived + +Depending on the path info provided with each `Request` we can serve different `Response`s: + +~~~ {.haskell} +app3 :: Application +app3 request respond = respond $ case rawPathInfo request of + "/" -> index + "/raw/" -> plainIndex + _ -> notFound + +plainIndex :: Response +plainIndex = responseFile + status200 + [("Content-Type", "text/plain")] + "index.html" + Nothing + +notFound :: Response +notFound = responseLBS + status404 + [("Content-Type", "text/plain")] + "404 - Not Found" +~~~ + + +Doing without overloaded strings +-------------------------------- + +For the sake of efficiency, WAI uses the [bytestring] package. We used GHCs [overloaded strings] to almost hide this fact. But we can easily do without. What follows is a more verbose definition of `notFound`, that works without GHC extensions: + +~~~ {.haskell .ignore} +import qualified Data.ByteString.Char8 as B8 +import qualified Data.ByteString.Lazy.Char8 as LB8 +import Data.CaseInsensitive (mk) + +notFound = responseLBS + status404 + [(mk $ B8.pack "Content-Type", B8.pack "text/plain")] + (LB8.pack "404 - Not Found") +~~~ + + + [wai]: http://hackage.haskell.org/package/wai + [warp]: http://hackage.haskell.org/package/warp + [overloaded strings]: http://www.haskell.org/ghc/docs/latest/html/users_guide/type-class-extensions.html#overloaded-strings + [bytestring]: http://hackage.haskell.org/package/bytestring diff --git a/test/Network/WaiSpec.hs b/test/Network/WaiSpec.hs new file mode 100644 --- /dev/null +++ b/test/Network/WaiSpec.hs @@ -0,0 +1,79 @@ +{-# LANGUAGE LambdaCase #-} +module Network.WaiSpec (spec) where + +import Test.Hspec +import Test.Hspec.QuickCheck (prop) +import Network.Wai +import Data.Word (Word8) +import Data.IORef +import qualified Data.ByteString as S +import qualified Data.ByteString.Lazy as L +import Data.ByteString.Builder (Builder, toLazyByteString, word8) +import Control.Monad (forM_) + +spec :: Spec +spec = do + describe "responseToStream" $ do + let getBody res = do + let (_, _, f) = responseToStream res + f $ \streamingBody -> do + builderRef <- newIORef mempty + let add :: Builder -> IO () + add b = atomicModifyIORef builderRef $ \builder -> + (builder `mappend` b, ()) + flush :: IO () + flush = return () + streamingBody add flush + L.toStrict . toLazyByteString <$> readIORef builderRef + prop "responseLBS" $ \bytes -> do + body <- getBody $ responseLBS undefined undefined $ L.pack bytes + body `shouldBe` S.pack bytes + prop "responseBuilder" $ \bytes -> do + body <- getBody $ responseBuilder undefined undefined + $ mconcat $ map word8 bytes + body `shouldBe` S.pack bytes + prop "responseStream" $ \chunks -> do + body <- getBody $ responseStream undefined undefined $ \sendChunk _ -> + forM_ chunks $ \chunk -> sendChunk $ mconcat $ map word8 chunk + body `shouldBe` S.concat (map S.pack chunks) + it "responseFile total" $ do + let fp = "wai.cabal" + body <- getBody $ responseFile undefined undefined fp Nothing + expected <- S.readFile fp + body `shouldBe` expected + prop "responseFile partial" $ \offset' count' -> do + let fp = "wai.cabal" + totalBS <- S.readFile fp + let total = S.length totalBS + offset = abs offset' `mod` total + count = abs count' `mod` (total - offset) + body <- getBody $ responseFile undefined undefined fp $ Just FilePart + { filePartOffset = fromIntegral offset + , filePartByteCount = fromIntegral count + , filePartFileSize = fromIntegral total + } + let expected = S.take count $ S.drop offset totalBS + body `shouldBe` expected + describe "lazyRequestBody" $ do + prop "works" $ \chunks -> do + req <- mkRequestFromChunks chunks + body <- lazyRequestBody req + body `shouldBe` L.fromChunks (map S.pack chunks) + it "is lazy" $ do + let req = setRequestBodyChunks (error "requestBody") defaultRequest + _ <- lazyRequestBody req + return () + describe "strictRequestBody" $ do + prop "works" $ \chunks -> do + req <- mkRequestFromChunks chunks + body <- strictRequestBody req + body `shouldBe` L.fromChunks (map S.pack chunks) + +mkRequestFromChunks :: [[Word8]] -> IO Request +mkRequestFromChunks chunks = do + ref <- newIORef $ map S.pack $ filter (not . null) chunks + pure $ + flip setRequestBodyChunks defaultRequest $ + atomicModifyIORef ref $ \case + [] -> ([], S.empty) + x:y -> (y, x) diff --git a/test/Spec.hs b/test/Spec.hs new file mode 100644 --- /dev/null +++ b/test/Spec.hs @@ -0,0 +1,1 @@ +{-# OPTIONS_GHC -F -pgmF hspec-discover #-} diff --git a/wai.cabal b/wai.cabal --- a/wai.cabal +++ b/wai.cabal @@ -1,30 +1,50 @@ +Cabal-Version: >=1.10 Name: wai -Version: 1.1.0.1 +Version: 3.2.4 Synopsis: Web Application Interface. Description: Provides a common protocol for communication between web applications and web servers. -License: BSD3 + . + API docs and the README are available at . +License: MIT License-file: LICENSE Author: Michael Snoyman Maintainer: michael@snoyman.com Homepage: https://github.com/yesodweb/wai Category: Web Build-Type: Simple -Cabal-Version: >=1.6 Stability: Stable +extra-source-files: README.md ChangeLog.md Source-repository head type: git location: git://github.com/yesodweb/wai.git Library - Build-Depends: base >= 4 && < 5 - , bytestring >= 0.9.1.4 && < 0.10 - , blaze-builder >= 0.2.1.4 && < 0.4 - , conduit >= 0.2 && < 0.3 - , network >= 2.2.1.5 && < 2.4 - , http-types >= 0.6 && < 0.7 - , text >= 0.7 && < 0.12 - , transformers >= 0.2.2 && < 0.3 - , vault >= 0.1 && < 0.2 + default-language: Haskell2010 + Build-Depends: base >= 4.12 && < 5 + , bytestring >= 0.10.4 + , network >= 2.2.1.5 + , http-types >= 0.7 + , text >= 0.7 + , vault >= 0.3 && < 0.4 Exposed-modules: Network.Wai + Network.Wai.Internal ghc-options: -Wall + +test-suite test + default-language: Haskell2010 + hs-source-dirs: test + main-is: Spec.hs + type: exitcode-stdio-1.0 + ghc-options: -threaded -Wall + cpp-options: -DTEST + build-depends: base >= 4.8 && < 5 + , wai + , hspec + , bytestring + other-modules: Network.WaiSpec + build-tool-depends: hspec-discover:hspec-discover + +source-repository head + type: git + location: git://github.com/yesodweb/wai.git