Copyright | (c) Patrick Brisbin 2010 Paul Rouse 2014-2016 |
---|---|
License | MIT |
Maintainer | Paul Rouse <pyr@doynton.org> |
Stability | Stable |
Portability | Portable |
Safe Haskell | None |
Language | Haskell2010 |
A Yesod authentication plugin designed to look users up in a Persistent database where the hash of their password is stored.
Releases 1.6 finishes the process of removing compatibility with old (pre 1.3) databases. Please see https://github.com/paul-rouse/yesod-auth-hashdb/blob/master/Upgrading.md
To use this in a Yesod application, the foundation data type must be an instance of YesodPersist, and the username and hashed passwords should be added to the database. The following steps give an outline of what is required.
You need a database table to store user records: in a scaffolded site it might look like:
User name Text -- user name used to uniquely identify users password Text Maybe -- password hash for HashDB UniqueUser name
Create an instance of HashDBUser
for this data type:
import Yesod.Auth.HashDB (HashDBUser(..)) .... instance HashDBUser User where userPasswordHash = userPassword setPasswordHash h u = u { userPassword = Just h }
In the YesodAuth instance declaration for your app, include authHashDB
like so:
import Yesod.Auth.HashDB (authHashDB) .... instance YesodAuth App where .... authPlugins _ = [ authHashDB (Just . UniqueUser), .... ] getAuthId creds = ... -- Perhaps modify scaffolding: see below
The argument to authHashDB
is a function which takes a Text
and
produces a Maybe
containing a Unique
value to look up in the User
table. The example (Just . UniqueUser)
shown here works for the
model outlined above.
In the scaffolding, the definition of getAuthId
contains code to
add a user who is not already in the database. Depending on how users
are administered, this may not make sense when using HashDB, so consider
whether it should be removed.
For a real application, the developer should provide some sort of
of administrative interface for setting passwords; it needs to call
setPassword
and save the result in the database. However, if you
need to initialise the database by hand, you can generate the correct
password hash as follows:
ghci -XOverloadedStrings > import Yesod.Auth.Util.PasswordStore > makePassword "MyPassword" 17
where "17" is the default strength parameter (defaultStrength
) used
in this module.
Custom Login Form
Instead of using the built-in HTML form, a custom one can be supplied
by using authHashDBWithForm
instead of authHashDB
.
The custom form needs to be given as a function returning a Widget, since it has to build in the supplied "action" URL, and it must provide two text fields called "username" and "password". For example, the following modification of the outline code given above would replace the default form with a very minimal one which has no labels and a simple layout.
instance YesodAuth App where .... authPlugins _ = [ authHashDBWithForm myform (Just . UniqueUser), .... ] myform :: Route App -> Widget myform action = $(whamletFile "templates/loginform.hamlet")
where templates/loginform.hamlet contains
<form method="post" action="@{action}"> <input name="username"> <input type="password" name="password"> <input type="submit" value="Login">
If a CSRF token needs to be embedded in a custom form, code must be
included in the widget to add it - see defaultForm
in the source
code of this module for an example.
JSON Interface
This plugin provides sufficient tools to build a complete JSON-based authentication flow. We assume that a design goal is to avoid URLs being built into the client, so all of the URLs needed are passed in JSON data.
To start the process, Yesod's defaultErrorHandler produces a JSON response if the HTTP Accept header gives "application/json" precedence over HTML. For a NotAuthenticated error, the status is 401 and the response contains the URL to use for authentication: this is the route which will be handled by the loginHandler method of the YesodAuth instance, which normally returns a login form.
Leaving the loginHandler aside for a moment, the final step - supported by this plugin since version 1.6 - is to POST the credentials for authentication in a JSON object. This object must include the properties "username" and "password". In the HTML case this would be the form submission, but here we want to use JSON instead.
In a JSON interface, the purpose of the loginHandler is to tell the
client the URL for submitting the credentials. This requires a
custom loginHandler, since the default one generates HTML only.
It can find the correct URL by using the submitRouteHashDB
function defined in this module.
Writing the loginHandler is made a little messy by the fact that its type allows only HTML content. A work-around is to send JSON as a short-circuit response, but we still make the choice using selectRep so as to get its matching of content types. Here is an example which is geared around using HashDB on its own, supporting both JSON and HTML clients:
instance YesodAuth App where .... loginHandler = do submission <- submitRouteHashDB render <- lift getUrlRender typedContent@(TypedContent ct _) <- selectRep $ do provideRepType typeHtml $ return emptyContent -- Dummy: the real Html version is at the end provideJson $ object [("loginUrl", toJSON $ render submission)] when (ct == typeJson) $ sendResponse typedContent -- Short-circuit JSON response defaultLoginHandler -- Html response
Synopsis
- class HashDBUser user where
- userPasswordHash :: user -> Maybe Text
- setPasswordHash :: Text -> user -> user
- defaultStrength :: Int
- setPasswordStrength :: (MonadIO m, HashDBUser user) => Int -> Text -> user -> m user
- setPassword :: (MonadIO m, HashDBUser user) => Text -> user -> m user
- validatePass :: HashDBUser u => u -> Text -> Maybe Bool
- upgradePasswordHash :: (MonadIO m, HashDBUser user) => Int -> user -> m (Maybe user)
- validateUser :: HashDBPersist site user => Unique user -> Text -> HandlerFor site Bool
- authHashDB :: HashDBPersist site user => (Text -> Maybe (Unique user)) -> AuthPlugin site
- authHashDBWithForm :: forall site user. HashDBPersist site user => (Route site -> WidgetFor site ()) -> (Text -> Maybe (Unique user)) -> AuthPlugin site
- submitRouteHashDB :: YesodAuth site => AuthHandler site (Route site)
Documentation
class HashDBUser user where Source #
The type representing user information stored in the database should be an instance of this class. It just provides the getter and setter used by the functions in this module.
userPasswordHash :: user -> Maybe Text Source #
Getter used by validatePass
and upgradePasswordHash
to
retrieve the password hash from user data
:: Text | Password hash |
-> user | |
-> user |
Setter used by setPassword
and upgradePasswordHash
. Produces a
version of the user data with the hash set to the new value.
defaultStrength :: Int Source #
Default strength used for passwords (see Yesod.Auth.Util.PasswordStore for details).
setPasswordStrength :: (MonadIO m, HashDBUser user) => Int -> Text -> user -> m user Source #
Set password for user, using the given strength setting. Use this
function, or setPassword
, to produce a user record containing the
hashed password. Unlike previous versions of this module, no separate
salt field is required for new passwords (but it may still be required
for compatibility while old password hashes remain in the database).
This function does not change the database; the calling application is responsible for saving the data which is returned.
setPassword :: (MonadIO m, HashDBUser user) => Text -> user -> m user Source #
As setPasswordStrength
, but using the defaultStrength
validatePass :: HashDBUser u => u -> Text -> Maybe Bool Source #
Validate a plaintext password against the hash in the user data structure.
The result distinguishes two types of validation failure, which may be useful in an application which supports multiple authentication methods:
- Just False - the user has a password set up, but the given one does not match it
- Nothing - the user does not have a password (
userPasswordHash
returns Nothing)
Since 1.4.1
upgradePasswordHash :: (MonadIO m, HashDBUser user) => Int -> user -> m (Maybe user) Source #
Upgrade existing user credentials to a stronger hash. The existing hash will have been produced from a weaker setting in the current algorithm. Use this function to produce an updated user record to store in the database.
As of version 1.5 this function cannot be used to upgrade a hash which has a non-empty separate salt field. Such entries would have been produced originally by versions of this module prior to 1.3, but may have been upgraded using earlier versions of this function.
Returns Nothing if the user has no password (ie if userPasswordHash
u
is Nothing
) or if the password hash is not in the correct format.
Interface to database and Yesod.Auth
:: HashDBPersist site user | |
=> Unique user | User unique identifier |
-> Text | Password in plaintext |
-> HandlerFor site Bool |
Given a user ID and password in plaintext, validate them against
the database values. This function simply looks up the user id in the
database and calls validatePass
to do the work.
authHashDB :: HashDBPersist site user => (Text -> Maybe (Unique user)) -> AuthPlugin site Source #
Prompt for username and password, validate that against a database which holds the username and a hash of the password
authHashDBWithForm :: forall site user. HashDBPersist site user => (Route site -> WidgetFor site ()) -> (Text -> Maybe (Unique user)) -> AuthPlugin site Source #
Like authHashDB
, but with an extra parameter to supply a custom HTML
form.
The custom form should be specified as a function which takes a route to use as the form action, and returns a Widget containing the form. The form must use the supplied route as its action URL, and, when submitted, it must send two text fields called "username" and "password".
Please see the example in the documentation at the head of this module.
Since 1.3.2
submitRouteHashDB :: YesodAuth site => AuthHandler site (Route site) Source #
The route, in the parent site, to which the username and password
should be sent in order to log in. This function is particularly
useful in constructing a loginHandler
function which provides a
JSON response. See the "JSON Interface" section above for more
details.
Since 1.6