warp-3.2.8: A fast, light-weight web server for WAI applications.

Safe HaskellNone
LanguageHaskell98

Network.Wai.Handler.Warp

Contents

Description

A fast, light-weight HTTP server handler for WAI.

HTTP/1.0, HTTP/1.1 and HTTP/2 are supported. For HTTP/2, Warp supports direct and ALPN (in TLS) but not upgrade.

Note on slowloris timeouts: to prevent slowloris attacks, timeouts are used at various points in request receiving and response sending. One interesting corner case is partial request body consumption; in that case, Warp's timeout handling is still in effect, and the timeout will not be triggered again. Therefore, it is recommended that once you start consuming the request body, you either:

  • consume the entire body promptly
  • call the pauseTimeout function

For more information, see https://github.com/yesodweb/wai/issues/351.

Synopsis

Run a Warp server

All of these automatically serve the same Application over HTTP/1, HTTP/1.1, and HTTP/2.

run :: Port -> Application -> IO () Source

Run an Application on the given port. This calls runSettings with defaultSettings.

runEnv :: Port -> Application -> IO () Source

Run an Application on the port present in the PORT environment variable. Uses the Port given when the variable is unset. This calls runSettings with defaultSettings.

Since 3.0.9

runSettings :: Settings -> Application -> IO () Source

Run an Application with the given Settings. This opens a listen socket on the port defined in Settings and calls runSettingsSocket.

runSettingsSocket :: Settings -> Socket -> Application -> IO () Source

This installs a shutdown handler for the given socket and calls runSettingsConnection with the default connection setup action which handles plain (non-cipher) HTTP. When the listen socket in the second argument is closed, all live connections are gracefully shut down.

The supplied socket can be a Unix named socket, which can be used when reverse HTTP proxying into your application.

Note that the settingsPort will still be passed to Applications via the serverPort record.

Settings

data Settings Source

Various Warp server settings. This is purposely kept as an abstract data type so that new settings can be added without breaking backwards compatibility. In order to create a Settings value, use defaultSettings and the various 'set' functions to modify individual fields. For example:

setTimeout 20 defaultSettings

defaultSettings :: Settings Source

The default settings for the Warp server. See the individual settings for the default value.

Setters

setPort :: Port -> Settings -> Settings Source

Port to listen on. Default value: 3000

Since 2.1.0

setHost :: HostPreference -> Settings -> Settings Source

Interface to bind to. Default value: HostIPv4

Since 2.1.0

setOnException :: (Maybe Request -> SomeException -> IO ()) -> Settings -> Settings Source

What to do with exceptions thrown by either the application or server. Default: defaultOnException

Since 2.1.0

setOnExceptionResponse :: (SomeException -> Response) -> Settings -> Settings Source

A function to create a Response when an exception occurs. Default: defaultOnExceptionResponse

Note that an application can handle its own exceptions without interfering with Warp:

myApp :: Application
myApp request respond = innerApp `catch` onError
  where
    onError = respond . response500 request

response500 :: Request -> SomeException -> Response
response500 req someEx = responseLBS status500 -- ...

Since 2.1.0

setOnOpen :: (SockAddr -> IO Bool) -> Settings -> Settings Source

What to do when a connection is opened. When False is returned, the connection is closed immediately. Otherwise, the connection is going on. Default: always returns True.

Since 2.1.0

setOnClose :: (SockAddr -> IO ()) -> Settings -> Settings Source

What to do when a connection is closed. Default: do nothing.

Since 2.1.0

setTimeout :: Int -> Settings -> Settings Source

Timeout value in seconds. Default value: 30

Since 2.1.0

setManager :: Manager -> Settings -> Settings Source

Use an existing timeout manager instead of spawning a new one. If used, settingsTimeout is ignored.

Since 2.1.0

setFdCacheDuration :: Int -> Settings -> Settings Source

Cache duration time of file descriptors in seconds. 0 means that the cache mechanism is not used.

The FD cache is an optimization that is useful for servers dealing with static files. However, if files are being modified, it can cause incorrect results in some cases. Therefore, we disable it by default. If you know that your files will be static or you prefer performance to file consistency, it's recommended to turn this on; a reasonable value for those cases is 10. Enabling this cache results in drastic performance improvement for file transfers.

Default value: 0, was previously 10

Since 3.0.13

setFileInfoCacheDuration :: Int -> Settings -> Settings Source

Cache duration time of file information in seconds. 0 means that the cache mechanism is not used.

The file information cache is an optimization that is useful for servers dealing with static files. However, if files are being modified, it can cause incorrect results in some cases. Therefore, we disable it by default. If you know that your files will be static or you prefer performance to file consistency, it's recommended to turn this on; a reasonable value for those cases is 10. Enabling this cache results in drastic performance improvement for file transfers.

Default value: 0

setBeforeMainLoop :: IO () -> Settings -> Settings Source

Code to run after the listening socket is ready but before entering the main event loop. Useful for signaling to tests that they can start running, or to drop permissions after binding to a restricted port.

Default: do nothing.

Since 2.1.0

setNoParsePath :: Bool -> Settings -> Settings Source

Perform no parsing on the rawPathInfo.

This is useful for writing HTTP proxies.

Default: False

Since 2.1.0

setInstallShutdownHandler :: (IO () -> IO ()) -> Settings -> Settings Source

A code to install shutdown handler.

For instance, this code should set up a UNIX signal handler. The handler should call the first argument, which closes the listen socket, at shutdown.

Default: does not install any code.

Since 3.0.1

setServerName :: ByteString -> Settings -> Settings Source

Default server name if application does not set one.

Since 3.0.2

setMaximumBodyFlush :: Maybe Int -> Settings -> Settings Source

The maximum number of bytes to flush from an unconsumed request body.

By default, Warp does not flush the request body so that, if a large body is present, the connection is simply terminated instead of wasting time and bandwidth on transmitting it. However, some clients do not deal with that situation well. You can either change this setting to Nothing to flush the entire body in all cases, or in your application ensure that you always consume the entire request body.

Default: 8192 bytes.

Since 3.0.3

setFork :: (((forall a. IO a -> IO a) -> IO ()) -> IO ()) -> Settings -> Settings Source

Code to fork a new thread to accept a connection.

This may be useful if you need OS bound threads, or if you wish to develop an alternative threading model.

Default: void . forkIOWithUnmask

Since 3.0.4

setProxyProtocolNone :: Settings -> Settings Source

Do not use the PROXY protocol.

Since 3.0.5

setProxyProtocolRequired :: Settings -> Settings Source

Require PROXY header.

This is for cases where a "dumb" TCP/SSL proxy is being used, which cannot add an X-Forwarded-For HTTP header field but has enabled support for the PROXY protocol.

See http://www.haproxy.org/download/1.5/doc/proxy-protocol.txt and http://docs.aws.amazon.com/ElasticLoadBalancing/latest/DeveloperGuide/TerminologyandKeyConcepts.html#proxy-protocol.

Only the human-readable header format (version 1) is supported. The binary header format (version 2) is not supported.

Since 3.0.5

setProxyProtocolOptional :: Settings -> Settings Source

Use the PROXY header if it exists, but also accept connections without the header. See setProxyProtocolRequired.

WARNING: This is contrary to the PROXY protocol specification and using it can indicate a security problem with your architecture if the web server is directly accessable to the public, since it would allow easy IP address spoofing. However, it can be useful in some cases, such as if a load balancer health check uses regular HTTP without the PROXY header, but proxied connections do include the PROXY header.

Since 3.0.5

setSlowlorisSize :: Int -> Settings -> Settings Source

Size in bytes read to prevent Slowloris protection. Default value: 2048

Since 3.1.2

setHTTP2Disabled :: Settings -> Settings Source

Disable HTTP2.

Since 3.1.7

setLogger Source

Arguments

:: (Request -> Status -> Maybe Integer -> IO ())

request, status, maybe file-size

-> Settings 
-> Settings 

Setting a log function.

Since 3.X.X

setServerPushLogger Source

Arguments

:: (Request -> ByteString -> Integer -> IO ())

request, path, file-size

-> Settings 
-> Settings 

Setting a log function for HTTP/2 server push.

Since: 3.2.7

setGracefulShutdownTimeout :: Maybe Int -> Settings -> Settings Source

Set the graceful shutdown timeout. A timeout of Nothing will wait indefinitely, and a number, if provided, will be treated as seconds to wait for requests to finish, before shutting down the server entirely.

Since 3.2.8

Getters

getPort :: Settings -> Port Source

Get the listening port.

Since 2.1.1

getHost :: Settings -> HostPreference Source

Get the interface to bind to.

Since 2.1.1

getOnOpen :: Settings -> SockAddr -> IO Bool Source

Get the action on opening connection.

getOnClose :: Settings -> SockAddr -> IO () Source

Get the action on closeing connection.

getOnException :: Settings -> Maybe Request -> SomeException -> IO () Source

Get the exception handler.

getGracefulShutdownTimeout :: Settings -> Maybe Int Source

Get the graceful shutdown timeout

Since 3.2.8

Exception handler

defaultOnException :: Maybe Request -> SomeException -> IO () Source

Printing an exception to standard error if defaultShouldDisplayException returns True.

Since: 3.1.0

defaultShouldDisplayException :: SomeException -> Bool Source

Apply the logic provided by defaultOnException to determine if an exception should be shown or not. The goal is to hide exceptions which occur under the normal course of the web server running.

Since 2.1.3

Exception response handler

defaultOnExceptionResponse :: SomeException -> Response Source

Sending 400 for bad requests. Sending 500 for internal server errors.

Since: 3.1.0

exceptionResponseForDebug :: SomeException -> Response Source

Exception handler for the debugging purpose. 500, text/plain, a showed exception.

Since: 2.0.3.2

Data types

data HostPreference :: *

Which host to bind.

Note: The IsString instance recognizes the following special values:

  • * means HostAny - "any IPv4 or IPv6 hostname"
  • *4 means HostIPv4 - "any IPv4 or IPv6 hostname, IPv4 preferred"
  • !4 means HostIPv4Only - "any IPv4 hostname"
  • *6 means HostIPv6@ - "any IPv4 or IPv6 hostname, IPv6 preferred"
  • !6 means HostIPv6Only - "any IPv6 hostname"

Note that the permissive * values allow binding to an IPv4 or an IPv6 hostname, which means you might be able to successfully bind to a port more times than you expect (eg once on the IPv4 localhost 127.0.0.1 and again on the IPv6 localhost 0:0:0:0:0:0:0:1).

Any other value is treated as a hostname. As an example, to bind to the IPv4 local host only, use "127.0.0.1".

type Port = Int Source

TCP port number.

Utilities

pauseTimeout :: Request -> IO () Source

Explicitly pause the slowloris timeout.

This is useful for cases where you partially consume a request body. For more information, see https://github.com/yesodweb/wai/issues/351

Since 3.0.10

data FileInfo Source

File information.

Constructors

FileInfo 

Fields

fileInfoName :: !FilePath
 
fileInfoSize :: !Integer
 
fileInfoTime :: HTTPDate

Modification time

fileInfoDate :: ByteString

Modification time in the GMT format

getFileInfo :: Request -> FilePath -> IO FileInfo Source

Getting file information of the target file.

This function first uses a stat(2) or similar system call to obtain information of the target file, then registers it into the internal cache. From the next time, the information is obtained from the cache. This reduces the overhead to call the system call. The internal cache is refreshed every duration specified by setFileInfoCacheDuration.

This function throws an IO exception if the information is not available. For instance, the target file does not exist. If this function is used an a Request generated by a WAI backend besides Warp, it also throws an IO exception.

Since 3.1.10

withApplication :: IO Application -> (Port -> IO a) -> IO a Source

Runs the given Application on a free port. Passes the port to the given operation and executes it, while the Application is running. Shuts down the server before returning.

Since: 3.2.4

withApplicationSettings :: Settings -> IO Application -> (Port -> IO a) -> IO a Source

withApplication with given Settings. This will ignore the port value set by setPort in Settings.

Since: 3.2.7

testWithApplication :: IO Application -> (Port -> IO a) -> IO a Source

Same as withApplication but with different exception handling: If the given Application throws an exception, testWithApplication will re-throw the exception to the calling thread, possibly interrupting the execution of the given operation.

This is handy for running tests against an Application over a real network port. When running tests, it's useful to let exceptions thrown by your Application propagate to the main thread of the test-suite.

The exception handling makes this function unsuitable for use in production. Use withApplication instead.

Since: 3.2.4

openFreePort :: IO (Port, Socket) Source

Opens a socket on a free port and returns both port and socket.

Since: 3.2.4

Version

warpVersion :: String Source

The version of Warp.

HTTP/2

HTTP2 data

data HTTP2Data Source

HTTP/2 specific data.

Since: 3.2.7

defaultHTTP2Data :: HTTP2Data Source

Default HTTP/2 specific data.

Since: 3.2.7

getHTTP2Data :: Request -> IO (Maybe HTTP2Data) Source

Getting HTTP2Data through vault of the request. Warp uses this to receive HTTP2Data from Middleware.

Since: 3.2.7

setHTTP2Data :: Request -> Maybe HTTP2Data -> IO () Source

Setting HTTP2Data through vault of the request. Application or Middleware should use this.

Since: 3.2.7

modifyHTTP2Data :: Request -> (Maybe HTTP2Data -> Maybe HTTP2Data) -> IO () Source

Modifying HTTP2Data through vault of the request. Application or Middleware should use this.

Since: 3.2.8

Push promise

data PushPromise Source

HTTP/2 push promise or sever push.

Since: 3.2.7

promisedPath :: PushPromise -> ByteString Source

Accessor for a URL path in PushPromise. E.g. "/style/default.css".

Since: 3.2.7

promisedFile :: PushPromise -> FilePath Source

Accessor for FilePath in PushPromise. E.g. "FILE_PATH/default.css".

Since: 3.2.7

promisedResponseHeaders :: PushPromise -> ResponseHeaders Source

Accessor for ResponseHeaders in PushPromise "content-type" must be specified. Default value: [].

Since: 3.2.7

promisedWeight :: PushPromise -> Weight Source

Accessor for Weight in PushPromise. Default value: 16.

Since: 3.2.7

defaultPushPromise :: PushPromise Source

Default push promise.

Since: 3.2.7