feat(api): implement MSC4143 RTC transports discovery endpoint

Add dedicated \`GET /_matrix/client/v1/rtc/transports\` and \`GET /_matrix/client/unstable/org.matrix.msc4143/rtc/transports\` endpoints for MatrixRTC focus discovery (MSC4143), replacing the deprecated well-known approach.

Move RTC foci configuration from \`[global.well_known]\` into a new \`[global.matrix_rtc]\` config section with a \`foci\` field. Remove \`rtc_foci\` from the \`.well-known/matrix/client\` response. Update LiveKit setup documentation accordingly.

Closes #1431

conduwuit-example.toml

@@ -1844,17 +1844,6 @@
 #
 #support_mxid =
 
-# A list of MatrixRTC foci URLs which will be served as part of the
-# MSC4143 client endpoint at /.well-known/matrix/client.  If you're
-# setting up livekit, you'd want something like:
-# rtc_focus_server_urls = [
-#     { type = "livekit", livekit_service_url = "https://livekit.example.com" },
-# ]
-#
-# To disable, set this to be an empty vector (`[]`).
-#
-#rtc_focus_server_urls = []
-
 [global.blurhashing]
 
 # blurhashing x component, 4 is recommended by https://blurha.sh/
@@ -1873,6 +1862,23 @@
 #
 #blurhash_max_raw_size = 33554432
 
+[global.matrix_rtc]
+
+# A list of MatrixRTC foci (transports) which will be served via the
+# MSC4143 RTC transports endpoint at
+# `/_matrix/client/v1/rtc/transports`. If you're setting up livekit,
+# you'd want something like:
+# ```toml
+# [global.matrix_rtc]
+# foci = [
+#     { type = "livekit", livekit_service_url = "https://livekit.example.com" },
+# ]
+# ```
+#
+# To disable, set this to an empty list (`[]`).
+#
+#foci = []
+
 [global.ldap]
 
 # Whether to enable LDAP login.

docs/calls/livekit.mdx

@@ -78,47 +78,19 @@ You will need to allow ports `7881/tcp` and `50100:50200/udp` through your firew
 
 ### 3. Telling clients where to find LiveKit
 
-To tell clients where to find LiveKit, you need to add the address of your `lk-jwt-service` to your client .well-known file. To do so, in the config section `global.well-known`, add (or modify) the option `rtc_focus_server_urls`.
+To tell clients where to find LiveKit, you need to add the address of your `lk-jwt-service` to the `[global.matrix_rtc]` config section using the `foci` option.
 
-The variable should be a list of servers serving as MatrixRTC endpoints to serve in the well-known file to the client.
+The variable should be a list of servers serving as MatrixRTC endpoints. Clients discover these via the `/_matrix/client/v1/rtc/transports` endpoint (MSC4143).
 
 ```toml
-rtc_focus_server_urls = [
+[global.matrix_rtc]
+foci = [
     { type = "livekit", livekit_service_url = "https://livekit.example.com" },
 ]
 ```
 
 Remember to replace the URL with the address you are deploying your instance of lk-jwt-service to.
 
-#### Serving .well-known manually
-
-If you don't let Continuwuity serve your `.well-known` files, you need to add the following lines to your `.well-known/matrix/client` file, remembering to replace the URL with your own `lk-jwt-service` deployment:
-
-```json
-  "org.matrix.msc4143.rtc_foci": [
-    {
-      "type": "livekit",
-      "livekit_service_url": "https://livekit.example.com"
-    }
-  ]
-```
-
-The final file should look something like this:
-
-```json
-{
-  "m.homeserver": {
-    "base_url":"https://matrix.example.com"
-  },
-  "org.matrix.msc4143.rtc_foci": [
-    {
-      "type": "livekit",
-      "livekit_service_url": "https://livekit.example.com"
-    }
-  ]
-}
-```
-
 ### 4. Configure your Reverse Proxy
 
 Reverse proxies can be configured in many different ways - so we can't provide a step by step for this.

src/api/client/well_known.rs

@@ -27,10 +27,23 @@ pub(crate) async fn well_known_client(
 		identity_server: None,
 		sliding_sync_proxy: Some(SlidingSyncProxyInfo { url: client_url }),
 		tile_server: None,
-		rtc_foci: services.config.well_known.rtc_focus_server_urls.clone(),
+		rtc_foci: vec![],
 	})
 }
 
+/// # `GET /_matrix/client/v1/rtc/transports`
+/// # `GET /_matrix/client/unstable/org.matrix.msc4143/rtc/transports`
+///
+/// Returns the list of MatrixRTC foci (transports) configured for this
+/// homeserver, implementing MSC4143.
+pub(crate) async fn get_rtc_transports(
+	State(services): State<crate::State>,
+) -> Result<impl IntoResponse> {
+	Ok(Json(serde_json::json!({
+		"rtc_foci": services.config.matrix_rtc.foci,
+	})))
+}
+
 /// # `GET /.well-known/matrix/support`
 ///
 /// Server support contact and support page of a homeserver's domain.

src/api/router.rs

@@ -184,6 +184,14 @@ pub fn build(router: Router<State>, server: &Server) -> Router<State> {
 		.ruma_route(&client::put_suspended_status)
 		.ruma_route(&client::well_known_support)
 		.ruma_route(&client::well_known_client)
+		.route(
+			"/_matrix/client/v1/rtc/transports",
+			get(client::get_rtc_transports),
+		)
+		.route(
+			"/_matrix/client/unstable/org.matrix.msc4143/rtc/transports",
+			get(client::get_rtc_transports),
+		)
 		.route("/_conduwuit/server_version", get(client::conduwuit_server_version))
 		.route("/_continuwuity/server_version", get(client::conduwuit_server_version))
 		.ruma_route(&client::room_initial_sync_route)

src/core/config/mod.rs

@@ -2080,6 +2080,12 @@ pub struct Config {
 	/// display: nested
 	#[serde(default)]
 	pub blurhashing: BlurhashConfig,
+
+	/// Configuration for MatrixRTC (MSC4143) transport discovery.
+	/// display: nested
+	#[serde(default)]
+	pub matrix_rtc: MatrixRtcConfig,
+
 	#[serde(flatten)]
 	#[allow(clippy::zero_sized_map_values)]
 	// this is a catchall, the map shouldn't be zero at runtime
@@ -2144,19 +2150,6 @@ pub struct WellKnownConfig {
 	/// If no email or mxid is specified, all of the server's admins will be
 	/// listed.
 	pub support_mxid: Option<OwnedUserId>,
-
-	/// A list of MatrixRTC foci URLs which will be served as part of the
-	/// MSC4143 client endpoint at /.well-known/matrix/client.  If you're
-	/// setting up livekit, you'd want something like:
-	/// rtc_focus_server_urls = [
-	///     { type = "livekit", livekit_service_url = "https://livekit.example.com" },
-	/// ]
-	///
-	/// To disable, set this to be an empty vector (`[]`).
-	///
-	/// default: []
-	#[serde(default = "default_rtc_focus_urls")]
-	pub rtc_focus_server_urls: Vec<RtcFocusInfo>,
 }
 
 #[derive(Clone, Copy, Debug, Deserialize, Default)]
@@ -2184,6 +2177,27 @@ pub struct BlurhashConfig {
 	pub blurhash_max_raw_size: u64,
 }
 
+#[derive(Clone, Debug, Deserialize, Default)]
+#[config_example_generator(filename = "conduwuit-example.toml", section = "global.matrix_rtc")]
+pub struct MatrixRtcConfig {
+	/// A list of MatrixRTC foci (transports) which will be served via the
+	/// MSC4143 RTC transports endpoint at
+	/// `/_matrix/client/v1/rtc/transports`. If you're setting up livekit,
+	/// you'd want something like:
+	/// ```toml
+	/// [global.matrix_rtc]
+	/// foci = [
+	///     { type = "livekit", livekit_service_url = "https://livekit.example.com" },
+	/// ]
+	/// ```
+	///
+	/// To disable, set this to an empty list (`[]`).
+	///
+	/// default: []
+	#[serde(default)]
+	pub foci: Vec<RtcFocusInfo>,
+}
+
 #[derive(Clone, Debug, Default, Deserialize)]
 #[config_example_generator(filename = "conduwuit-example.toml", section = "global.ldap")]
 pub struct LdapConfig {
@@ -2660,9 +2674,6 @@ fn default_rocksdb_stats_level() -> u8 { 1 }
 #[inline]
 pub fn default_default_room_version() -> RoomVersionId { RoomVersionId::V11 }
 
-#[must_use]
-pub fn default_rtc_focus_urls() -> Vec<RtcFocusInfo> { vec![] }
-
 fn default_ip_range_denylist() -> Vec<String> {
 	vec![
 		"127.0.0.0/8".to_owned(),