openiddict-documentation/guides/contributing-a-new-web-provider.md

Contributing a new Web provider

As part of the OpenIddict 4.0 effort, a new client stack has been added to OpenIddict. To simplify integrating with social and enterprise providers that offer OAuth 2.0 and OpenID Connect services, a companion package (named OpenIddict.Client.WebIntegration) has been added to the client stack. While it shares some similarities with the existing aspnet-contrib OAuth 2.0 providers, there are actually important technical differences:

• Unlike the ASP.NET Core OAuth 2.0 base handler by the aspnet-contrib providers, the OpenIddict client is a dual-protocol OAuth 2.0 + OpenID Connect stack, which means it can support both protocols while enforcing all the security checks required by these protocols.

• While the aspnet-contrib providers only work on ASP.NET Core, the OpenIddict providers can not only be used in ASP.NET Core and OWIN/ASP.NET 4.x applications, but also in Windows and Linux desktop applications without requiring any platform-specific code.

• Unlike the aspnet-contrib providers, the source code needed to materialize the OpenIddict web providers is created dynamically using Roslyn Source Generators and a XML file that includes all the supported providers with the configuration needed to properly generate them. By eliminating all the plumbing code, the OpenIddict web providers are much easier to maintain and update.

• To guarantee interoperability and make the best security choices, the OpenIddict client heavily relies on server configuration metadata, which differs from the approach used by the ASP.NET Core OAuth 2.0 base handler, that doesn't support the OpenID Connect discovery and OAuth 2.0 authorization server metadata specifications.

Due to these differences, contributing a new provider to the OpenIddict stack is quite different from adding an aspnet-contrib provider:

Add a new <Provider> node for the new provider

To add a new OpenIddict web provider, the first step is to add a new <Provider> node to the OpenIddictClientWebIntegrationProviders.xml file. For instance:

<Provider Name="Zendesk" Id="89fdfe22-c796-4227-a44a-d9cd3c467bbb"
          Documentation="https://developer.zendesk.com/documentation/live-chat/getting-started/auth/">
</Provider>

If available, a link to the official documentation MUST be added. If multiple languages are available, the following order SHOULD be used:

• English
• French
• Spanish
• Any other language

Warning

The added provider MUST be placed in the XML file such that the alphabetical order is respected.

Add an <Environment> node per supported environment

The second step is to determine whether the service offers multiple environments (e.g Production, Testing or Development).

• If the provider supports multiple environments, multiple <Environment> nodes - one per environment - MUST be added under <Provider>:

<Provider Name="Salesforce" Id="ce5bc4bc-6133-4e87-85ad-626b3c0a4427">
  <Environment Name="Production" />

  <Environment Name="Development" />
</Provider>

Warning

When specifying multiple environments, the production environment MUST always appear first.

• If the provider doesn't support multiple environment, a single <Environment> MUST be added (the Name attribute SHOULD be omitted):

<Provider Name="Google" Id="e0e90ce7-adb5-4b05-9f54-594941e5d960">
  <Environment />
</Provider>

Add the appropriate configuration for each environment

The third step is the most complicated one: adding the appropriate configuration for each of the added environments.

For that, you MUST first determine whether the environment supports OpenID Connect discovery or OAuth 2.0 authorization server metadata. In some cases, this information will be mentioned in the official documentation, but it's not always true. By convention, the server metadata is typically served from https://provider/.well-known/openid-configuration: if you get a valid JSON document from this endpoint, the server supports OpenID Connect/OAuth 2.0 server metadata.

• If the server supports OpenID Connect/OAuth 2.0 server metadata, add an Issuer attribute to <Environment> corresponding to the provider address without the /.well-known/openid-configuration part. For instance, Google exposes its discovery document at https://accounts.google.com/.well-known/openid-configuration so the correct issuer to use is https://accounts.google.com/:

<Provider Name="Google" Id="e0e90ce7-adb5-4b05-9f54-594941e5d960">
  <Environment Issuer="https://accounts.google.com/" />
</Provider>

• If the server doesn't support OpenID Connect/OAuth 2.0 server metadata, you MUST add an Issuer attribute (corresponding to either the value given in the documentation or the base address of the server) and a <Configuration> node with the static configuration needed by the OpenIddict client to communicate with the remote authorization server. For instance:

<Provider Name="Reddit" Id="01ae8033-935c-43b9-8568-eaf4d08c0613">
  <Environment Issuer="https://www.reddit.com/">
    <Configuration AuthorizationEndpoint="https://www.reddit.com/api/v1/authorize"
                   TokenEndpoint="https://www.reddit.com/api/v1/access_token"
                   UserinfoEndpoint="https://oauth.reddit.com/api/v1/me">
      <GrantType Value="authorization_code" />
      <GrantType Value="refresh_token" />
    </Configuration>
  </Environment>
</Provider>

Note

If the provider doesn't support grant_type=refresh_token and only supports the authorization code flow (typically with non-expiring access tokens), the <GrantType> nodes MUST be removed for clarity, as the authorization code flow is always considered supported by default if no <GrantType> is present:

<Provider Name="Reddit" Id="01ae8033-935c-43b9-8568-eaf4d08c0613">
  <Environment Issuer="https://www.reddit.com/">
    <Configuration AuthorizationEndpoint="https://www.reddit.com/api/v1/authorize"
                   TokenEndpoint="https://www.reddit.com/api/v1/access_token"
                   UserinfoEndpoint="https://oauth.reddit.com/api/v1/me" />
  </Environment>
</Provider>

Caution

If the provider doesn't support server metadata but is known to support Proof Key for Code Exchange (PKCE), a <CodeChallengeMethod> node MUST be added under <Configuration> to ensure the OpenIddict client will send appropriate code_challenge/code_challenge_method parameters:

<Provider Name="Fitbit" Id="10a558b9-8c81-47cc-8941-e54d0432fd51">
  <Environment Issuer="https://www.fitbit.com/">
    <Configuration AuthorizationEndpoint="https://www.fitbit.com/oauth2/authorize"
                   TokenEndpoint="https://api.fitbit.com/oauth2/token"
                   UserinfoEndpoint="https://api.fitbit.com/1/user/-/profile.json">
      <CodeChallengeMethod Value="S256" />
    </Configuration>
  </Environment>
</Provider>

Note

Some providers use a multitenant configuration that relies on a subdomain, a custom domain or a virtual path to discriminate tenant instances. If the provider you want to support requires adding a dynamic part in one of its URIs, a <Setting> node MUST be added under <Provider> to store the tenant name. Once added, the URIs can include a placeholder of the same name:

<Provider Name="Zendesk" Id="89fdfe22-c796-4227-a44a-d9cd3c467bbb">
  <!--
    Note: Zendesk is a multitenant provider that relies on subdomains to identify instances.
    As such, the following URIs all include a {tenant} placeholder that will be dynamically
    replaced by OpenIddict at runtime by the tenant configured in the Zendesk settings.
  -->

  <Environment Issuer="https://{tenant}.zendesk.com/">
    <Configuration AuthorizationEndpoint="https://{tenant}.zendesk.com/oauth/authorizations/new"
                   TokenEndpoint="https://{tenant}.zendesk.com/oauth/tokens"
                   UserinfoEndpoint="https://{tenant}.zendesk.com/api/v2/users/me" />
  </Environment>

  <Setting PropertyName="Tenant" ParameterName="tenant" Type="String" Required="true"
           Description="The tenant used to identify the Zendesk instance" />
</Provider>

Unwrap userinfo responses if necessary

If the provider returns wrapped or nested userinfo responses (e.g under a response or data node), the UnwrapUserinfoResponse handler in OpenIddictClientWebIntegrationHandlers.Userinfo.cs must be updated to unwrap the userinfo payload and allow OpenIddict to map them to flat CLR Claim instances:

/// <summary>
/// Contains the logic responsible for extracting the userinfo response
/// from nested JSON nodes (e.g "data") for the providers that require it.
/// </summary>
public sealed class UnwrapUserinfoResponse : IOpenIddictClientHandler<ExtractUserinfoResponseContext>
{
    /// <summary>
    /// Gets the default descriptor definition assigned to this handler.
    /// </summary>
    public static OpenIddictClientHandlerDescriptor Descriptor { get; }
        = OpenIddictClientHandlerDescriptor.CreateBuilder<ExtractUserinfoResponseContext>()
            .UseSingletonHandler<UnwrapUserinfoResponse>()
            .SetOrder(int.MaxValue - 50_000)
            .SetType(OpenIddictClientHandlerType.BuiltIn)
            .Build();

    /// <inheritdoc/>
    public ValueTask HandleAsync(ExtractUserinfoResponseContext context)
    {
        if (context is null)
        {
            throw new ArgumentNullException(nameof(context));
        }

        context.Response = context.Registration.ProviderType switch
        {
            // Fitbit returns a nested "user" object.
            ProviderTypes.Fitbit => new(context.Response["user"]?.GetNamedParameters() ??
                throw new InvalidOperationException(SR.FormatID0334("user"))),

            // StackExchange returns an "items" array containing a single element.
            ProviderTypes.StackExchange => new(context.Response["items"]?[0]?.GetNamedParameters() ??
                throw new InvalidOperationException(SR.FormatID0334("items/0"))),

            // SubscribeStar returns a nested "user" object that is itself nested in a GraphQL "data" node.
            ProviderTypes.SubscribeStar => new(context.Response["data"]?["user"]?.GetNamedParameters() ??
                throw new InvalidOperationException(SR.FormatID0334("data/user"))),

            _ => context.Response
        };

        return default;
    }
}

Note

If you're unsure whether the provider returns wrapped responses or not, the received payload can be found in the logs after a successful authorization flow:

OpenIddict.Client.OpenIddictClientDispatcher: Information: The userinfo response returned by https://contoso.com/users/me was successfully extracted: {
  "data": {
    "username": "odile.donat",
    "name": "Odile Donat",
    "email": "odile.donat@fabrikam.com"
  }
}.

If the provider doesn't support standard OpenID Connect userinfo, map the provider-specific claims to their ClaimTypes equivalent

If the provider doesn't return an id_token and doesn't offer a standard userinfo endpoint, it is likely it uses custom parameters to represent things like the user identifier. If so, update the MapCustomWebServicesFederationClaims event handler in OpenIddictClientWebIntegrationHandlers.cs to map these parameters to the usual WS-Federation claims exposed by the .NET BCL ClaimTypes class, which simplifies integration with libraries like ASP.NET Core Identity:

/// <summary>
/// Contains the logic responsible for mapping select custom claims to
/// their WS-Federation equivalent for the providers that require it.
/// </summary>
public sealed class MapCustomWebServicesFederationClaims : IOpenIddictClientHandler<ProcessAuthenticationContext>
{
    /// <summary>
    /// Gets the default descriptor definition assigned to this handler.
    /// </summary>
    public static OpenIddictClientHandlerDescriptor Descriptor { get; }
        = OpenIddictClientHandlerDescriptor.CreateBuilder<ProcessAuthenticationContext>()
            .AddFilter<RequireWebServicesFederationClaimMappingEnabled>()
            .UseSingletonHandler<MapCustomWebServicesFederationClaims>()
            .SetOrder(MapStandardWebServicesFederationClaims.Descriptor.Order + 1_000)
            .SetType(OpenIddictClientHandlerType.BuiltIn)
            .Build();

    /// <inheritdoc/>
    public ValueTask HandleAsync(ProcessAuthenticationContext context)
    {
        if (context is null)
        {
            throw new ArgumentNullException(nameof(context));
        }

        context.MergedPrincipal.SetClaim(ClaimTypes.Email, context.Registration.ProviderType switch
        {
            // ServiceChannel returns the user identifier as a custom "Email" node:
            ProviderTypes.ServiceChannel => (string?) context.UserinfoResponse?["Email"],

            _ => context.MergedPrincipal.GetClaim(ClaimTypes.Email)
        });

        context.MergedPrincipal.SetClaim(ClaimTypes.Name, context.Registration.ProviderType switch
        {
            // ServiceChannel returns the user identifier as a custom "UserName" node:
            ProviderTypes.ServiceChannel => (string?) context.UserinfoResponse?["UserName"],

            _ => context.MergedPrincipal.GetClaim(ClaimTypes.Name)
        });

        context.MergedPrincipal.SetClaim(ClaimTypes.NameIdentifier, context.Registration.ProviderType switch
        {
            // ServiceChannel returns the user identifier as a custom "UserId" node:
            ProviderTypes.ServiceChannel => (string?) context.UserinfoResponse?["UserId"],

            _ => context.MergedPrincipal.GetClaim(ClaimTypes.NameIdentifier)
        });

        return default;
    }
}

Test the generated provider

If the targeted service is fully standard-compliant, no additional configuration should be required at this point. To confirm it, build the solution and add an instance of the new provider to the OpenIddict.Sandbox.AspNetCore.Client sandbox:

• Update Startup.cs to register your new provider:

// Register the Web providers integrations.
options.UseWebProviders()
       // ... other providers...
       .Add[provider name](options =>
       {
           options.SetClientId("bXgwc0U3N3A3YWNuaWVsdlRmRWE6MTpjaQ");
           options.SetClientSecret("VcohOgBp-6yQCurngo4GAyKeZh0D6SUCCSjJgEo1uRzJarjIUS");
           options.SetRedirectUri("callback/login/[provider name]");
       });

• Update AuthenticationController.cs to allow triggering challenges pointing to the new provider:

// Note: OpenIddict always validates the specified provider name when handling the challenge operation,
// but the provider can also be validated earlier to return an error page or a special HTTP error code.
if (!string.Equals(provider, "Local", StringComparison.Ordinal) &&
    // ... other providers...
    !string.Equals(provider, [provider name], StringComparison.Ordinal))
{
    return BadRequest();
}

• Update Index.cshtml under Views\Home to include a login button for the new provider:

<button class="btn btn-lg btn-success" type="submit" name="provider" value="[provider name]">
    Sign in using [provider name]
</button>

Note

Unless you agree to share your sandbox credentials with the OpenIddict developers, the changes made to the sandbox project don't need to be committed and included in your pull request.

If necessary, add the necessary workarounds for the provider to work correctly

If an error occurs during the authentication process, the provider MAY require one or multiple workarounds for the integration to work correctly:

• The provider MAY require sending the client credentials as part of the Authorization header using basic authentication (i.e client_secret_basic). Providers that implement OpenID Connect discovery or OAuth 2.0 authorization server metadata will typically return the client authentication methods they support. If the provider doesn't expose its metadata, the supported methods MUST be added manually to the static configuration using one or multiple <TokenEndpointAuthMethod>:

<Provider Name="Twitter" Id="1fd20ab5-d3f2-40aa-8c91-094f71652c65">
  <Environment Issuer="https://twitter.com/">
    <Configuration AuthorizationEndpoint="https://twitter.com/i/oauth2/authorize"
                   TokenEndpoint="https://api.twitter.com/2/oauth2/token"
                   UserinfoEndpoint="https://api.twitter.com/2/users/me">
      <CodeChallengeMethod Value="S256" />

      <TokenEndpointAuthMethod Value="client_secret_basic" />
    </Configuration>
  </Environment>
</Provider>

• The provider MAY require sending one or multiple default or required scopes. If so, the default/required scopes MUST be added to the <Environment> node:

<Provider Name="Twitter" Id="1fd20ab5-d3f2-40aa-8c91-094f71652c65">
  <Environment Issuer="https://twitter.com/">
    <Configuration AuthorizationEndpoint="https://twitter.com/i/oauth2/authorize"
                   TokenEndpoint="https://api.twitter.com/2/oauth2/token"
                   UserinfoEndpoint="https://api.twitter.com/2/users/me">
      <CodeChallengeMethod Value="S256" />

      <TokenEndpointAuthMethod Value="client_secret_basic" />
    </Configuration>

    <!--
      Note: Twitter requires requesting the "tweet.read" and "users.read" scopes for the
      userinfo endpoint to work correctly. As such, these 2 scopes are marked as required
      so they are always sent even if they were not explicitly added by the user.
    -->

    <Scope Name="tweet.read" Default="true" Required="true" />
    <Scope Name="users.read" Default="true" Required="true" />
  </Environment>
</Provider>

• The provider MAY require sending the scopes using a different separator than the standard one. While the OAuth 2.0 specification requires using a space to separate multiple scopes, some providers require using a different separator (typically, a comma). If the provider you're adding requires such a hack, update the FormatNonStandardScopeParameter event handler present in OpenIddictClientWebIntegrationHandlers.cs to use the correct separator required by the provider.

/// <summary>
/// Contains the logic responsible for overriding the standard "scope"
/// parameter for providers that are known to use a non-standard format.
/// </summary>
public class FormatNonStandardScopeParameter : IOpenIddictClientHandler<ProcessChallengeContext>
{
    /// <summary>
    /// Gets the default descriptor definition assigned to this handler.
    /// </summary>
    public static OpenIddictClientHandlerDescriptor Descriptor { get; }
        = OpenIddictClientHandlerDescriptor.CreateBuilder<ProcessChallengeContext>()
            .AddFilter<RequireInteractiveGrantType>()
            .UseSingletonHandler<FormatNonStandardScopeParameter>()
            .SetOrder(AttachChallengeParameters.Descriptor.Order + 500)
            .SetType(OpenIddictClientHandlerType.BuiltIn)
            .Build();

    /// <inheritdoc/>
    public ValueTask HandleAsync(ProcessChallengeContext context)
    {
        if (context is null)
        {
            throw new ArgumentNullException(nameof(context));
        }

        context.Request.Scope = context.Registration.ProviderType switch
        {
            // The following providers are known to use comma-separated scopes instead of
            // the standard format (that requires using a space as the scope separator):
            ProviderTypes.Reddit => string.Join(",", context.Scopes),

            _ => context.Request.Scope
        };

        return default;
    }
}

Note

If the provider still doesn't work, it's unfortunately very likely more complex workarounds will be required. If you're not familiar with the OpenIddict events model, open a ticket in the openiddict-core repository to get help.

Send a pull request against the openiddict-core repository

Once you've been able to confirm that your provider works correctly, all you need to do is send a PR so that it can be added to the openiddict-repo and ship with the already supported providers as part of the next update.