impl MSC2966: register clients dynamically

src/api/client/oidc/mod.rs

@@ -14,8 +14,10 @@ mod discovery;
 mod login;
 mod authorize;
 mod token;
+mod register;
 
 pub(crate) use self::discovery::get_auth_metadata;
 pub(crate) use self::login::oidc_login;
 pub(crate) use self::authorize::{authorize, authorize_consent};
+pub(crate) use self::register::register_client;
 pub(crate) use self::token::token;

src/api/client/oidc/register.rs

@@ -0,0 +1,93 @@
+use oxide_auth::primitives::prelude::Client;
+use axum::{
+	Json,
+	extract::State,
+};
+use conduwuit::{Result, err};
+use ruma::DeviceId;
+use reqwest::Url;
+
+/// The required parameters to register a new client for OAuth2 application.
+#[derive(serde::Deserialize, Clone)]
+pub(crate) struct ClientQuery {
+	/// Human-readable name.
+    client_name: String,
+	/// A public page that tells more about the client. All other links must be within.
+    client_uri: Url,
+	/// Redirect URIs declared by the client. At least one.
+	redirect_uris: Vec<Url>,
+	/// Must be ["code"].
+	response_types: Vec<String>,
+	/// Must include "authorization_type" and "refresh_token".
+	grant_types: Vec<String>,
+	//contacts: Vec<String>,
+	/// Can be "none".
+	token_endpoint_auth_method: String,
+	/// Link to the logo.
+	logo_uri: Option<Url>,
+	/// Link to the client's policy.
+	policy_uri: Option<Url>,
+	/// Link to the terms of service.
+	tos_uri: Option<Url>,
+	/// Defaults to "web" if not present.
+	application_type: Option<String>,
+}
+
+/// A successful response that the client was registered.
+#[derive(serde::Serialize)]
+pub(crate) struct ClientResponse {
+	client_id: String,
+	client_name: String,
+	client_uri: Url,
+	logo_uri: Option<Url>,
+	tos_uri: Option<Url>,
+	policy_uri: Option<Url>,
+	redirect_uris: Vec<Url>,
+	token_endpoint_auth_method: String,
+	response_types: Vec<String>,
+	grant_types: Vec<String>,
+	application_type: Option<String>,
+}
+
+/// # `GET /_matrix/client/unstable/org.matrix.msc2964/device/register`
+///
+/// Register a client, as specified in [MSC2966]. This client, "device" in Oidc parlance,
+/// will have the right to submit [super::authorize::authorize] requests.
+///
+/// [MSC2966]: https://github.com/matrix-org/matrix-spec-proposals/pull/2966
+pub(crate) async fn register_client(
+	State(services): State<crate::State>,
+	Json(client): Json<ClientQuery>,
+) -> Result<Json<ClientResponse>> {
+	let Some(redirect_uri) = client.redirect_uris.first().cloned() else {
+		return Err(err!(Request(Unknown(
+			"register request should contain at least a redirect_uri"
+		))));
+	};
+	let device_id = DeviceId::new();
+	let scope = format!(
+		"urn:matrix:org.matrix.msc2967.client:api:* urn:matrix:org.matrix.msc2967.client:device:{}",
+		device_id
+	);
+	// TODO check if the users service needs an update.
+	//services.users.update_device_metadata();
+	services.oidc.register_client(&Client::public(
+		&device_id.to_string(),
+		redirect_uri.into(),
+		scope.parse().expect("device ID should parse in Matrix scope"),
+	))?;
+
+	Ok(Json(ClientResponse {
+		client_id: device_id.to_string(),
+		client_name: client.client_name.clone(),
+		client_uri: client.client_uri.clone(),
+		redirect_uris: client.redirect_uris.clone(),
+		logo_uri: client.logo_uri.clone(),
+		policy_uri: client.policy_uri.clone(),
+		tos_uri: client.tos_uri.clone(),
+		token_endpoint_auth_method: client.token_endpoint_auth_method.clone(),
+		response_types: client.response_types.clone(),
+		grant_types: client.grant_types.clone(),
+		application_type: client.application_type.clone(),
+	}))
+}

src/api/router.rs

@@ -129,6 +129,9 @@ pub fn build(router: Router<State>, server: &Server) -> Router<State> {
 			post(client::oidc_login))
 		.route("/_matrix/client/unstable/org.matrix.msc2964/token",
 			post(client::token))
+		// MSC2966 route.
+		.route("/_matrix/client/unstable/org.matrix.msc2964/device/register",
+			post(client::register_client))
 		.ruma_route(&client::send_message_event_route)
 		.ruma_route(&client::send_state_event_for_key_route)
 		.ruma_route(&client::get_state_events_route)

src/service/oidc/mod.rs

@@ -45,6 +45,16 @@ impl crate::Service for Service {
 }
 
 impl Service {
+	pub fn register_client(&self, client: &Client) -> Result<()> {
+		self
+			.registrar
+			.lock()
+			.expect("lockable registrar")
+			.register_client(client.clone());
+
+		Ok(())
+	}
+
 	pub fn preconfigured() -> Self {
 		Service {
 			registrar: Mutex::new(