backend: gate existing endpoints behind auth and app permissions

Move /api/pair, /api/apps, and /api/stream/start under the session
auth middleware so they require a valid session token. Add app-level
permission filtering: non-admin users only see and can stream apps
they have been explicitly granted access to. Admins bypass all
permission checks.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

gamestream-webtransport-proxy/src/apps.rs

@@ -5,6 +5,7 @@ use serde::{Deserialize, Serialize};
 use tracing::{debug, error};
 
 use crate::{
+    auth,
     common,
     common::{AppError, AppResult},
     responses,
@@ -45,7 +46,8 @@ struct GetAppsResponse {
 #[craft]
 impl crate::backend::Backend {
     #[craft(endpoint(status_codes(StatusCode::OK, StatusCode::INTERNAL_SERVER_ERROR)))]
-    pub async fn get_apps(self: ::std::sync::Arc<Self>) -> AppResult<Json<GetAppsResponse>> {
+    pub async fn get_apps(self: ::std::sync::Arc<Self>, depot: &mut Depot) -> AppResult<Json<GetAppsResponse>> {
+        let user = auth::get_user_from_depot(depot).cloned();
         let standard_error = Err(AppError {
             status_code: StatusCode::INTERNAL_SERVER_ERROR,
             description: "failed to get available apps".to_string(),
@@ -143,6 +145,21 @@ impl crate::backend::Backend {
             get_apps_resp.apps.insert(server.name, resp_vec);
         }
 
+        // Filter apps by user permissions (admins see everything)
+        if let Some(ref user) = user {
+            if !user.is_admin {
+                let permissions = self.db.get_permissions(&user.id).unwrap_or_default();
+                for (server_name, apps) in get_apps_resp.apps.iter_mut() {
+                    apps.retain(|app| {
+                        permissions.iter().any(|p| {
+                            p.server == *server_name && p.app_id == app.id as i64
+                        })
+                    });
+                }
+                get_apps_resp.apps.retain(|_, apps| !apps.is_empty());
+            }
+        }
+
         Ok(Json(get_apps_resp))
     }
 }

gamestream-webtransport-proxy/src/main.rs

@@ -76,16 +76,15 @@ async fn run_backend(port: u16) -> Result<()> {
     let router = Router::new()
         // Public auth routes
         .push(Router::with_path("api/auth/login").post(backend_arc.login()))
-        // Existing routes (not yet gated - will be gated in a subsequent commit)
-        .push(Router::with_path("api/pair").post(backend_arc.post_pair()))
-        .push(Router::with_path("api/apps").get(backend_arc.get_apps()))
-        .push(Router::with_path("api/stream/start").post(backend_arc.post_stream_start()))
         // Authenticated routes
         .push(
             Router::with_path("api")
                 .hoop(auth_middleware)
                 .push(Router::with_path("auth/logout").post(backend_arc.logout()))
                 .push(Router::with_path("auth/me").get(backend_arc.me()))
+                .push(Router::with_path("pair").post(backend_arc.post_pair()))
+                .push(Router::with_path("apps").get(backend_arc.get_apps()))
+                .push(Router::with_path("stream/start").post(backend_arc.post_stream_start()))
                 // Admin-only routes
                 .push(
                     Router::with_path("admin")

gamestream-webtransport-proxy/src/stream.rs

@@ -7,6 +7,7 @@ use serde::{Deserialize, Serialize};
 use tracing::{debug, error, info};
 
 use crate::{
+    auth,
     common::{AppError, AppResult, get_url},
     proxy, responses,
     state::{GamestreamServer, StateReadAccess, StateReader},
@@ -81,12 +82,32 @@ impl crate::backend::Backend {
         self: ::std::sync::Arc<Self>,
         body: salvo::oapi::extract::JsonBody<PostStreamStartParams>,
         req: &mut Request,
+        depot: &mut Depot,
     ) -> AppResult<Json<PostStreamStartResponse>> {
         let standard_error = Err(crate::common::AppError {
             status_code: StatusCode::INTERNAL_SERVER_ERROR,
             description: "Could not start stream".to_string(),
         });
 
+        // Check app permission
+        if let Some(user) = auth::get_user_from_depot(depot) {
+            if !user.is_admin {
+                match self.db.check_app_permission(&user.id, &body.server, body.id as i64) {
+                    Ok(true) => {}
+                    Ok(false) => {
+                        return Err(AppError {
+                            status_code: StatusCode::FORBIDDEN,
+                            description: "You do not have permission to access this application".to_string(),
+                        });
+                    }
+                    Err(e) => {
+                        error!("Permission check error: {e}");
+                        return standard_error;
+                    }
+                }
+            }
+        }
+
         let reader = self.state.read().await;
 
         let server = match get_server(&reader, &body.server) {