Add additional query parameters to the Azure B2C login url

Question

I'm implementing Azure B2C to a .NET MVC app, and I need to add an extra query parameter to the login url.

Here's how I've set it up in the startup.cs

var openIdConnectAuthenticationOptions = new OpenIdConnectAuthenticationOptions
            {
                // Generate the metadata address using the tenant and policy information
                MetadataAddress = String.Format(Globals.WellKnownMetadata, Globals.Tenant, Globals.DefaultPolicy),

                // These are standard OpenID Connect parameters, with values pulled from web.config
                ClientId = Globals.ClientId,
                RedirectUri = Globals.RedirectUri,
                PostLogoutRedirectUri = Globals.RedirectUri,

                // Specify the callbacks for each type of notifications
                Notifications = new OpenIdConnectAuthenticationNotifications
                {
                    RedirectToIdentityProvider = OnRedirectToIdentityProvider,
                    AuthorizationCodeReceived = OnAuthorizationCodeReceived,
                    AuthenticationFailed = OnAuthenticationFailed
                },

                // Specify the claim type that specifies the Name property.
                TokenValidationParameters = new TokenValidationParameters
                {
                    NameClaimType = "name",
                    ValidateIssuer = false
                },

                // Specify the scope by appending all of the scopes requested into one string (separated by a blank space)
                Scope = $"openid",
                ResponseType = "id_token",
            };

            app.UseOpenIdConnectAuthentication(
              openIdConnectAuthenticationOptions
            );

And when someone tries to visit an [authorized] tagged page, it sends them to this b2c url:

https://mytenant.b2clogin.com/mytenant.onmicrosoft.com/oauth2/v2.0/authorize?p=b2c_custom_signin&client_id=0000-000000-000-00&redirect_uri=https://localhost&response_type=id_token&scope=openid&x-client-SKU=ID_NET461&x-client-ver=5.3.0.0

However, I need to add an extra query parameter onto the end, "&appId=000-000-000", so the resulting login URL is:

https://mytenant.b2clogin.com/mytenant.onmicrosoft.com/oauth2/v2.0/authorize?p=b2c_custom_signin&client_id=0000-000000-000-00&redirect_uri=https://localhost&response_type=id_token&scope=openid&x-client-SKU=ID_NET461&x-client-ver=5.3.0.0 &appId=000-000-000

how would I go about doing this?

Pamela Peng Pamela Peng · Accepted Answer · 2020-10-16T02:18:51

I'm afraid you could not add the appId parameter, but I recommend to make use of the state parameter. You could use this parameter to send the value of appid as part of request and it gets returned back in response.

For more details, see here.

Add additional query parameters to the Azure B2C login url

1 Answers