yesod-auth-oauth2/src/Yesod/Auth/OAuth2/Slack.hs
patrick brisbin 8e434df38a Support hoauth2-2.0
The new major version improves the naming of the fields of the OAuth2
record type. This type is central to this library and we leak it freely.

Users who make their own plugins are expected to construct values of
this type to pass into our functions, this makes the new version
disruptive to our code and our users'.

We have two options:

1. Update and release our own new major version

   The major downside is that the current LTS resolver will then not
   update beyond our currently-released version. We have no immediate
   plans for new features in this library, but if we have bugs reported
   to be fixed we would either have to manage a complex backporting or
   ask our Stack users to wait for the next major LTS, which has
   historically been many months.

   Users who wish to use our new version would need to also bring in
   hoauth2, and who knows what else.

2. Release a fully-compatible update

   As mentioned, we leak OAuth2(..) through this library's interface. In
   order to be truly backwards-compatible, we would have to use CCP to
   define an "old style" OAuth2 and use that throughout, such that
   in-the-wild OAuth2 values continue to work as-is.

   This would not be a good long-term solution as it introduces a fair
   amount of naming confusion and will lead to import conflicts for any
   users who also import hoauth2-2.0 modules in the same project.

3. Release a mostly-compatible update

   This is the path this commit explores. We can update our own code to
   be hoauth2-2.0 compatible and use CPP to define the hoauth2-2.0-like
   OAuth2 if we're still on hoauth2-1.x.

   This gets us compiling in either case and "forward functional", with
   the exception of users who define their own plugins (which is rare).

   Because of that use-case, this should technically be a major version
   bump for ourselves (though I'm open to the argument we could treat
   the local-provider use-case differently), however it is still better
   than Option 1 in a few ways:

   - We still compile with hoauth2-1.x, so can be brought in easily as
     an isolated extra-dep
   - If there is a reported bug that we decide to only fix in the newer
     versions, the path for the user is better: they can pull us as an
     extra-dep and likely need no changes. Even if they're doing a
     custom plugin, the required changes are minor
2022-01-31 16:02:35 -05:00

76 lines
2.3 KiB
Haskell

{-# LANGUAGE OverloadedStrings #-}
-- |
-- OAuth2 plugin for https://slack.com/
--
-- * Authenticates against slack
-- * Uses slack user id as credentials identifier
--
module Yesod.Auth.OAuth2.Slack
( SlackScope(..)
, oauth2Slack
, oauth2SlackScoped
)
where
import Yesod.Auth.OAuth2.Prelude
import Network.HTTP.Client
(httpLbs, parseUrlThrow, responseBody, setQueryString)
import Yesod.Auth.OAuth2.Exception as YesodOAuth2Exception
data SlackScope
= SlackBasicScope
| SlackEmailScope
| SlackTeamScope
| SlackAvatarScope
scopeText :: SlackScope -> Text
scopeText SlackBasicScope = "identity.basic"
scopeText SlackEmailScope = "identity.email"
scopeText SlackTeamScope = "identity.team"
scopeText SlackAvatarScope = "identity.avatar"
newtype User = User Text
instance FromJSON User where
parseJSON = withObject "User" $ \root -> do
o <- root .: "user"
User <$> o .: "id"
pluginName :: Text
pluginName = "slack"
defaultScopes :: [SlackScope]
defaultScopes = [SlackBasicScope]
oauth2Slack :: YesodAuth m => Text -> Text -> AuthPlugin m
oauth2Slack = oauth2SlackScoped defaultScopes
oauth2SlackScoped :: YesodAuth m => [SlackScope] -> Text -> Text -> AuthPlugin m
oauth2SlackScoped scopes clientId clientSecret =
authOAuth2 pluginName oauth2 $ \manager token -> do
let param = encodeUtf8 $ atoken $ accessToken token
req <- setQueryString [("token", Just param)]
<$> parseUrlThrow "https://slack.com/api/users.identity"
userResponse <- responseBody <$> httpLbs req manager
either
(throwIO . YesodOAuth2Exception.JSONDecodingError pluginName)
(\(User userId) -> pure Creds
{ credsPlugin = pluginName
, credsIdent = userId
, credsExtra = setExtra token userResponse
}
)
$ eitherDecode userResponse
where
oauth2 = OAuth2
{ oauth2ClientId = clientId
, oauth2ClientSecret = Just clientSecret
, oauth2AuthorizeEndpoint =
"https://slack.com/oauth/authorize"
`withQuery` [scopeParam "," $ map scopeText scopes]
, oauth2TokenEndpoint = "https://slack.com/api/oauth.access"
, oauth2RedirectUri = Nothing
}