wai-cors
CORS for WAI
https://github.com/larskuhtz/wai-cors
Version on this page: | 0.2.6 |
LTS Haskell 22.37: | 0.2.7 |
Stackage Nightly 2024-10-11: | 0.2.7 |
Latest on Hackage: | 0.2.7 |
wai-cors-0.2.6@sha256:f8dfb382e13ab583fc201cf1bd41691b323ec6292b9b0c4dbde236c3dde20d09,4309
Module documentation for 0.2.6
- Network
- Network.Wai
- Network.Wai.Middleware
- Network.Wai
Cross-Origin Resource Sharing (CORS) For Wai
This package provides a Haskell implementation of CORS for WAI that aims to be compliant with http://www.w3.org/TR/cors.
Note On Security
This implementation doesn’t include any server side enforcement. By complying
with the CORS standard it enables the client (i.e. the web browser) to enforce
the CORS policy. For application authors it is strongly recommended to take
into account the security considerations in section 6.3 of the
CORS standard. In particular the application should
check that the value of the Origin
header matches the expectations.
Websocket connections don’t support CORS and are ignored by the CORS implementation in this package. However Websocket requests usually (at least for some browsers) include the @Origin@ header. Applications are expected to check the value of this header and respond with an error in case that its content doesn’t match the expectations.
Installation
Assuming the availability of recent versions of GHC and cabal this package is installed via
cabal update
cabal install wai-cors
Usage
The function ‘simpleCors’ enables support of simple cross-origin requests. More advanced CORS policies can be enabled by passing a ‘CorsResourcePolicy’ to the ‘cors’ middleware.
The file examples/Scotty.hs
shows how to support simple cross-origin requests (as
defined in http://www.w3.org/TR/cors) in a
scotty application.
{-# LANGUAGE OverloadedStrings #-}
module Main
( main
) where
import Network.Wai.Middleware.Cors
import Web.Scotty
main :: IO ()
main = scotty 8080 $ do
middleware simpleCors
matchAny "/" $ text "Success"
The result of following curl command will include the HTTP response
header Access-Control-Allow-Origin: *
.
curl -i http://127.0.0.1:8080 -H 'Origin: 127.0.0.1' -v
Documentation for more general usage can be found in the module Network.Wai.Middleware.Cors.
Test
In order to run the automated test suite PhantomJS (at least version 2.0) must be installed in the system.
cabal install --only-dependencies --enable-tests
cabal test --show-details=streaming
If PhantomJS is not available the tests can be exectued manually in a modern web-browser as follows.
Start the server application:
cd test
ghc -main-is Server Server.hs
./Server
Open the file test/index.html
in a modern web-browser. On page load a Javascript
script is exectued that runs the test suite and prints the result on the page.
Changes
0.2.6 (2017-12-01)
-
Removed ghc-7.6.3 and versions of wai<3.0 from the CI test matrix. These versions are still supported in the code but cabal may need some manual help to resolve dependencies.
-
Fixes and improvements to the documentation. Thanks to Frederik Hanghøj Iversen, Alex Collins, and Maximilian Tagher.
0.2.5
-
Support GHC-8.0.1.
-
Removed dependencies on parsers package.
0.2.4
- Fix bug #1.
Response header
Vary: Origin
is now included whencorsVaryOrigin
isTrue
andcorsOrigins
does not equalNothing
.
0.2.3
-
Added a test-suite to the package that uses PhantomJS to simulate a browser client.
-
Pass on websocket requests unchanged to the application. Add documentation that reminds the application author to check the
Origin
header for websocket requests. -
Move development source repository from https://github.com/alephcloud/wai-cors to https://github.com/larskuhtz/wai-cors.
0.2.2
-
Support GHC-7.10/base-4.8 without compiler warnings.
-
Drop dependency on errors package.
0.2.1
- Fix bug #8.
Accept empty list as value for
Access-Control-Request-Headers
.
0.2
This version may break existing code by changing the type of
CorsResourcePolicy
.
This version changes the behavior of simpleCorsResourcePolicy
: Before
it was a failure when the request didn’t contain an @Origin@ header.
With this version the request is passed unchanged to the application.
If an failure occurs during CORS processing the response has HTTP status
400 (bad request) and contains a short error messages. This behavior
can be changed with the new settings corsRequireOrigin
and
corsIgnorefailure
.
-
Remove setting
corsVerboseResponse
fromCorsResourcePolicy
. -
Add new settings
corsRequireOrigin
andcorsIgnoreFailure
toCorsResourcePolicy
.
0.1.4
- Support wai-3
0.1.3
- Improved documentation
0.1.2
-
Export type synonym
Origin
-
New easy-to-use middleware function
simpleCors
that supports just simple cross-origin requests -
The new value
simpleCorseResourcePolicy
is aCorseResourcePolicy
for simple cross-origin requests. -
Documentation has been slightly improved
-
Some code for testing
simpleCors
from a browser
0.1.1
-
Drop redundant dependencies on lens and ghc-prim
-
Fix typo in HTTP header field name
Access-Control-Allow-Credentials
0.1.0
- Initial version