Add conditional for login flows; filter out SSO when no providers configured.

Signed-off-by: Jason Volk <jason@zemos.net>

src/api/client/session/mod.rs

@@ -22,7 +22,10 @@ use ruma::api::client::session::{
 		v3::{DiscoveryInfo, HomeserverInfo, LoginInfo},
 	},
 };
-use tuwunel_core::{Err, Result, info, utils::stream::ReadyExt};
+use tuwunel_core::{
+	Err, Result, info,
+	utils::{BoolExt, stream::ReadyExt},
+};
 use tuwunel_service::users::device::generate_refresh_token;
 
 use self::{ldap::ldap_login, password::password_login};
@@ -45,28 +48,45 @@ pub(crate) async fn get_login_types_route(
 	InsecureClientIp(client): InsecureClientIp,
 	_body: Ruma<get_login_types::v3::Request>,
 ) -> Result<get_login_types::v3::Response> {
-	Ok(get_login_types::v3::Response::new(vec![
-		LoginType::Password(PasswordLoginType::default()),
+	let get_login_token = services.config.login_via_existing_session;
+
+	let identity_providers = services
+		.config
+		.sso_custom_providers_page
+		.is_false()
+		.then(|| services.config.identity_provider.iter())
+		.into_iter()
+		.flatten()
+		.cloned()
+		.map(|config| IdentityProvider {
+			id: config.id().to_owned(),
+			brand: Some(config.brand.clone().into()),
+			icon: config.icon,
+			name: config.name.unwrap_or(config.brand),
+		})
+		.collect();
+
+	let flows = [
 		LoginType::ApplicationService(ApplicationServiceLoginType::default()),
 		LoginType::Jwt(JwtLoginType::default()),
-		LoginType::Token(TokenLoginType {
-			get_login_token: services.config.login_via_existing_session,
-		}),
-		LoginType::Sso(SsoLoginType {
-			identity_providers: services
-				.config
-				.identity_provider
-				.iter()
-				.cloned()
-				.map(|config| IdentityProvider {
-					id: config.id().to_owned(),
-					brand: Some(config.brand.clone().into()),
-					icon: config.icon,
-					name: config.name.unwrap_or(config.brand),
-				})
-				.collect(),
-		}),
-	]))
+		LoginType::Password(PasswordLoginType::default()),
+		LoginType::Sso(SsoLoginType { identity_providers }),
+		LoginType::Token(TokenLoginType { get_login_token }),
+	];
+
+	Ok(get_login_types::v3::Response {
+		flows: flows
+			.into_iter()
+			.filter(|login_type| match login_type {
+				| LoginType::Sso(SsoLoginType { identity_providers })
+					if !services.config.sso_custom_providers_page
+						&& identity_providers.is_empty() =>
+					false,
+
+				| _ => true,
+			})
+			.collect(),
+	})
 }
 
 /// # `POST /_matrix/client/v3/login`

src/api/client/session/sso.rs

@@ -75,7 +75,8 @@ pub(crate) async fn sso_login_route(
 	_body: Ruma<sso_login::v3::Request>,
 ) -> Result<sso_login::v3::Response> {
 	Err!(Request(NotImplemented(
-		"SSO login without specific provider has not been implemented."
+		"sso_custom_providers_page has been enabled but this URL has not been overridden with \
+		 any custom page listing the available providers..."
 	)))
 }
 

src/core/config/mod.rs

@@ -2139,6 +2139,23 @@ pub struct Config {
 	#[serde(default = "default_one_time_key_limit")]
 	pub one_time_key_limit: usize,
 
+	/// Setting this option to true replaces the list of identity providers on
+	/// the client's login screen with a single button "Sign in with single
+	/// sign-on" linking to the URL `/_matrix/client/v3/login/sso/redirect`. The
+	/// deployment is expected to intercept this URL with their reverse-proxy to
+	/// provide a custom webpage listing providers; each entry linking or
+	/// redirecting back to one of the configured identity providers at
+	/// /_matrix/client/v3/login/sso/redirect/<client_id>`.
+	///
+	/// This option defaults to false, allowing the client to generate the list
+	/// of providers or hide all SSO-related options when none configured.
+	#[serde(default)]
+	pub sso_custom_providers_page: bool,
+
+	/// Under development; do not enable.
+	#[serde(default)]
+	pub sso_aware_preferred: bool,
+
 	// external structure; separate section
 	#[serde(default)]
 	pub blurhashing: BlurhashConfig,
@@ -2159,9 +2176,6 @@ pub struct Config {
 	#[serde(default)]
 	pub identity_provider: HashSet<IdentityProvider>,
 
-	#[serde(default)]
-	pub sso_aware_preferred: bool,
-
 	#[serde(flatten)]
 	#[allow(clippy::zero_sized_map_values)]
 	// this is a catchall, the map shouldn't be zero at runtime

tuwunel-example.toml

@@ -1834,7 +1834,20 @@
 #
 #one_time_key_limit = 256
 
-# This item is undocumented. Please contribute documentation for it.
+# Setting this option to true replaces the list of identity providers on
+# the client's login screen with a single button "Sign in with single
+# sign-on" linking to the URL `/_matrix/client/v3/login/sso/redirect`. The
+# deployment is expected to intercept this URL with their reverse-proxy to
+# provide a custom webpage listing providers; each entry linking or
+# redirecting back to one of the configured identity providers at
+# /_matrix/client/v3/login/sso/redirect/<client_id>`.
+#
+# This option defaults to false, allowing the client to generate the list
+# of providers or hide all SSO-related options when none configured.
+#
+#sso_custom_providers_page = false
+
+# Under development; do not enable.
 #
 #sso_aware_preferred = false