OAuth.AuthorizationCode

The authorization code grant type is used to obtain both access tokens and refresh tokens and is optimized for confidential clients. Since this is a redirection-based flow, the client must be capable of interacting with the resource owner's user-agent (typically a web browser) and capable of receiving incoming requests (via redirection) from the authorization server.

   +---------+                                +--------+
   |         |---(A)- Auth Redirection ------>|        |
   |         |                                |  Auth  |
   | Browser |                                | Server |
   |         |                                |        |
   |         |<--(B)- Redirection Callback ---|        |
   +---------+          (w/ Auth Code)        +--------+
     ^     |                                    ^    |
     |     |                                    |    |
    (A)   (B)                                   |    |
     |     |                                    |    |
     |     v                                    |    |
   +---------+                                  |    |
   |         |----(C)---- Auth Code ------------+    |
   | Elm App |                                       |
   |         |                                       |
   |         |<---(D)------ Access Token ------------+
   +---------+       (w/ Optional Refresh Token)

(A) The client initiates the flow by directing the resource owner's user-agent to the authorization endpoint.
(B) Assuming the resource owner grants access, the authorization server redirects the user-agent back to the client including an authorization code and any local state provided by the client earlier.
(C) The client requests an access token from the authorization server's token endpoint by including the authorization code received in the previous step.
(D) The authorization server authenticates the client and validates the authorization code. If valid, the authorization server responds back with an access token and, optionally, a refresh token.

After those steps, the client owns a Token that can be used to authorize any subsequent request.

Authorize

makeAuthorizationUrl : Authorization -> Url

Redirects the resource owner (user) to the resource provider server using the specified authorization flow.

parseCode : Url -> AuthorizationResult

Parse the location looking for a parameters set by the resource provider server after redirecting the resource owner (user).

Returns AuthorizationResult Empty when there's nothing

type alias Authorization =

{ clientId : String

, url : Url

, redirectUri : Url

, scope : List String

, state : Maybe String

}

Request configuration for an authorization (Authorization Code & Implicit flows)

clientId (REQUIRED): The client identifier issues by the authorization server via an off-band mechanism.
url (REQUIRED): The authorization endpoint to contact the authorization server.
redirectUri (OPTIONAL): After completing its interaction with the resource owner, the authorization server directs the resource owner's user-agent back to the client via this URL. May be already defined on the authorization server itself.
scope (OPTIONAL): The scope of the access request.
state (RECOMMENDED): An opaque value used by the client to maintain state between the request and callback. The authorization server includes this value when redirecting the user-agent back to the client. The parameter SHOULD be used for preventing cross-site request forgery.

type alias AuthorizationCode =

String

A simple type alias to ease readability of type signatures

type AuthorizationResult

= Empty

| Error AuthorizationError

| Success AuthorizationSuccess

Describes errors coming from attempting to parse a url after an OAuth redirection

Empty: means there were nothing (related to OAuth 2.0) to parse
Error: a successfully parsed OAuth 2.0 error
Success: a successfully parsed token and response

type alias AuthorizationSuccess =

{ code : AuthorizationCode

, state : Maybe String

}

The response obtained as a result of an authorization

code (REQUIRED): The authorization code generated by the authorization server. The authorization code MUST expire shortly after it is issued to mitigate the risk of leaks. A maximum authorization code lifetime of 10 minutes is RECOMMENDED. The client MUST NOT use the authorization code more than once. If an authorization code is used more than once, the authorization server MUST deny the request and SHOULD revoke (when possible) all tokens previously issued based on that authorization code. The authorization code is bound to the client identifier and redirection URI.
state (REQUIRED if state was present in the authorization request): The exact value received from the client

type alias AuthorizationError =

{ error : ErrorCode

, errorDescription : Maybe String

, errorUri : Maybe String

, state : Maybe String

}

Describes an OAuth error as a result of an authorization request failure

error (REQUIRED): A single ASCII error code.
errorDescription (OPTIONAL) Human-readable ASCII text providing additional information, used to assist the client developer in understanding the error that occurred. Values for the errorDescription parameter MUST NOT include characters outside the set %x20-21 / %x23-5B / %x5D-7E.
errorUri (OPTIONAL): A URI identifying a human-readable web page with information about the error, used to provide the client developer with additional information about the error. Values for the errorUri parameter MUST conform to the URI-reference syntax and thus MUST NOT include characters outside the set %x21 / %x23-5B / %x5D-7E.
state (REQUIRED if state was present in the authorization request): The exact value received from the client

Authenticate

makeTokenRequest :

(Result Error AuthenticationSuccess -> msg)

-> Authentication

-> RequestParts msg

Builds a the request components required to get a token from an authorization code

let req : Http.Request AuthenticationSuccess
    req = makeTokenRequest toMsg authentication |> Http.request

type alias Authentication =

{ credentials : Credentials

, code : String

, redirectUri : Url

, url : Url

}

Request configuration for an AuthorizationCode authentication

credentials (REQUIRED): Only the clientId is required. Specify a secret if a Basic OAuth is required by the resource provider.
code (REQUIRED): Authorization code from the authorization result
url (REQUIRED): Token endpoint of the resource provider
redirectUri (REQUIRED): Redirect Uri to your webserver used in the authorization step, provided here for verification.

type alias Credentials =

{ clientId : String

, secret : Maybe String

}

Describes at least a clientId and if define, a complete set of credentials with the secret. The secret is so-to-speak optional and depends on whether the authorization server you interact with requires a 'Basic' authentication on top of the authentication request. Provides it if you need to do so.

  { clientId = "<my-client-id>"
  , secret = Just "<my-client-secret>"
  }

type alias AuthenticationSuccess =

{ token : Token

, refreshToken : Maybe Token

, expiresIn : Maybe Int

, scope : List String

}

The response obtained as a result of an authentication (implicit or not)

token (REQUIRED): The access token issued by the authorization server.
refreshToken (OPTIONAL): The refresh token, which can be used to obtain new access tokens using the same authorization grant as described in Section 6.
expiresIn (RECOMMENDED): The lifetime in seconds of the access token. For example, the value "3600" denotes that the access token will expire in one hour from the time the response was generated. If omitted, the authorization server SHOULD provide the expiration time via other means or document the default value.
scope (OPTIONAL, if identical to the scope requested; otherwise, REQUIRED): The scope of the access token as described by Section 3.3.

type alias AuthenticationError =

{ error : ErrorCode

, errorDescription : Maybe String

, errorUri : Maybe String

}

Describes an OAuth error as a result of a request failure

error (REQUIRED): A single ASCII error code.
errorDescription (OPTIONAL) Human-readable ASCII text providing additional information, used to assist the client developer in understanding the error that occurred. Values for the errorDescription parameter MUST NOT include characters outside the set %x20-21 / %x23-5B / %x5D-7E.
errorUri (OPTIONAL): A URI identifying a human-readable web page with information about the error, used to provide the client developer with additional information about the error. Values for the errorUri parameter MUST conform to the URI-reference syntax and thus MUST NOT include characters outside the set %x21 / %x23-5B / %x5D-7E.

type alias RequestParts a =

{ method : String

, headers : List Header

, url : String

, body : Body

, expect : Expect a

, timeout : Maybe Float

, tracker : Maybe String

}

Parts required to build a request. This record is given to Http.request in order to create a new request and may be adjusted at will.

JSON Decoders

defaultAuthenticationSuccessDecoder : Decoder AuthenticationSuccess

Json decoder for a positive response. You may provide a custom response decoder using other decoders from this module, or some of your own craft.

defaultAuthenticationSuccessDecoder : Decoder AuthenticationSuccess
defaultAuthenticationSuccessDecoder =
    D.map4 AuthenticationSuccess
        tokenDecoder
        refreshTokenDecoder
        expiresInDecoder
        scopeDecoder

defaultAuthenticationErrorDecoder : Decoder AuthenticationError

Json decoder for an errored response.

case res of
    Err (Http.BadStatus { body }) ->
        case Json.decodeString OAuth.AuthorizationCode.defaultAuthenticationErrorDecoder body of
            Ok { error, errorDescription } ->
                doSomething


            _ ->
                parserFailed


    _ ->
        someOtherError

JSON Decoders (advanced)

defaultExpiresInDecoder : Decoder (Maybe Int)

Json decoder for an 'expire' timestamp

defaultScopeDecoder : Decoder (List String)

Json decoder for a 'scope'

lenientScopeDecoder : Decoder (List String)

Json decoder for a 'scope', allowing comma- or space-separated scopes

defaultTokenDecoder : Decoder Token

Json decoder for an 'access_token'

defaultRefreshTokenDecoder : Decoder (Maybe Token)

Json decoder for a 'refresh_token'

defaultErrorDecoder : Decoder ErrorCode

Json decoder for 'error' field

defaultErrorDescriptionDecoder : Decoder (Maybe String)

Json decoder for 'error_description' field

defaultErrorUriDecoder : Decoder (Maybe String)

Json decoder for 'error_uri' field

Query Parsers (advanced)

parseCodeWith : Parsers -> Url -> AuthorizationResult

See parseCode, but gives you the ability to provide your own custom parsers.

type alias Parsers =

{ codeParser : Parser (Maybe String)

, errorParser : Parser (Maybe ErrorCode)

, authorizationSuccessParser :

String -> Parser AuthorizationSuccess

, authorizationErrorParser : ErrorCode -> Parser AuthorizationError

}

Parsers used in the 'parseCode' function.

codeParser: looks for a 'code' string
errorParser: looks for an 'error' to build a corresponding ErrorCode
authorizationSuccessParser: selected when the tokenParser succeeded to parse the remaining parts
authorizationErrorParser: selected when the errorParser succeeded to parse the remaining parts

defaultParsers : Parsers

Default parsers according to RFC-6749

defaultCodeParser : Parser (Maybe String)

Default 'code' parser according to RFC-6749

defaultErrorParser : Parser (Maybe ErrorCode)

Default 'error' parser according to RFC-6749

defaultAuthorizationSuccessParser : String -> Parser AuthorizationSuccess

Default response success parser according to RFC-6749

defaultAuthorizationErrorParser : ErrorCode -> Parser AuthorizationError

Default response error parser according to RFC-6749