v25.17.9

changelog.md

@@ -1,5 +1,89 @@
 # Changelog
 
+## 2026-03-20 - 25.17.9 - fix(rustproxy-http)
+correct HTTP/3 host extraction and avoid protocol filtering during UDP route lookup
+
+- Use the URI host or strip the port from the Host header so HTTP/3 requests match routes consistently with TCP/HTTP handling.
+- Remove protocol filtering from HTTP/3 route lookup because QUIC transport already constrains routing to UDP and protocol validation happens earlier.
+
+## 2026-03-20 - 25.17.8 - fix(rustproxy)
+use SNI-based certificate resolution for QUIC TLS connections
+
+- Replaces static first-certificate selection with the shared CertResolver used by the TCP/TLS path.
+- Ensures QUIC connections can present the correct certificate per requested domain.
+- Keeps HTTP/3 ALPN configuration while improving multi-domain TLS handling.
+
+## 2026-03-20 - 25.17.7 - fix(readme)
+document QUIC and HTTP/3 compatibility caveats
+
+- Add notes explaining that GREASE frames are disabled on both server and client HTTP/3 paths to avoid interoperability issues
+- Document that the current HTTP/3 stack depends on pre-1.0 h3 ecosystem components and may still have rough edges
+
+## 2026-03-20 - 25.17.6 - fix(rustproxy-http)
+disable HTTP/3 GREASE for client and server connections
+
+- Switch the HTTP/3 server connection setup to use the builder API with send_grease(false)
+- Switch the HTTP/3 client handshake to use the builder API with send_grease(false) to improve compatibility
+
+## 2026-03-20 - 25.17.5 - fix(rustproxy)
+add HTTP/3 integration test for QUIC response stream FIN handling
+
+- adds an integration test covering HTTP/3 proxying over QUIC with TLS termination
+- verifies response bodies fully arrive and the client receives stream termination instead of hanging
+- adds test-only dependencies for quinn, h3, h3-quinn, rustls, bytes, and http
+
+## 2026-03-20 - 25.17.4 - fix(rustproxy-http)
+prevent HTTP/3 response body streaming from hanging on backend completion
+
+- extract and track Content-Length before consuming the response body
+- stop the HTTP/3 body loop when the stream reports end-of-stream or the expected byte count has been sent
+- add a per-frame idle timeout to avoid indefinite waits on stalled or close-delimited backend bodies
+
+## 2026-03-20 - 25.17.3 - fix(repository)
+no changes detected
+
+
+## 2026-03-20 - 25.17.2 - fix(rustproxy-http)
+enable TLS connections for HTTP/3 upstream requests when backend re-encryption or TLS is configured
+
+- Pass backend TLS client configuration into the HTTP/3 request handler.
+- Detect TLS-required upstream targets using route and target TLS settings before connecting.
+- Build backend request URIs with the correct http or https scheme to match the upstream connection.
+
+## 2026-03-20 - 25.17.1 - fix(rustproxy-routing)
+allow QUIC UDP TLS connections without SNI to match domain-restricted routes
+
+- Exempts UDP transport from the no-SNI rejection logic because QUIC encrypts the TLS ClientHello and SNI is unavailable at accept time
+- Adds regression tests to confirm QUIC route matching succeeds without SNI while TCP TLS without SNI remains rejected
+
+## 2026-03-19 - 25.17.0 - feat(rustproxy-passthrough)
+add PROXY protocol v2 client IP handling for UDP and QUIC listeners
+
+- propagate trusted proxy IP configuration into UDP and QUIC listener managers
+- extract and preserve real client addresses from PROXY protocol v2 headers for HTTP/3 and QUIC stream handling
+- apply rate limiting, session limits, routing, and metrics using the resolved client IP while preserving correct proxy return-path routing
+
+## 2026-03-19 - 25.16.3 - fix(rustproxy)
+upgrade fallback UDP listeners to QUIC when TLS certificates become available
+
+- Rebuild and apply QUIC TLS configuration during route and certificate updates instead of only when adding new UDP ports.
+- Add logic to drain UDP sessions, stop raw fallback listeners, and start QUIC endpoints on existing ports once TLS is available.
+- Retry QUIC endpoint creation during upgrade and fall back to rebinding raw UDP if the upgrade cannot complete.
+
+## 2026-03-19 - 25.16.2 - fix(rustproxy-http)
+cache backend Alt-Svc only from original upstream responses during protocol auto-detection
+
+- Moves Alt-Svc discovery into streaming response construction so it reads backend headers before response filters inject client-facing Alt-Svc values
+- Stores the protocol cache key in connection activity during auto-detect mode and clears it after HTTP/3 connection failure to avoid re-caching failed H3 routes
+- Prevents fallback requests from reintroducing stale or self-injected Alt-Svc entries that could cause repeated H3 retry loops
+
+## 2026-03-19 - 25.16.1 - fix(http-proxy)
+avoid repeated HTTP/3 recaching after QUIC fallback and document backend protocol selection
+
+- Suppress Alt-Svc HTTP/3 recaching after a failed QUIC backend connection to prevent repeated H3 timeout fallback loops
+- Force an ALPN probe on TCP fallback so auto detection correctly reselects HTTP/2 or HTTP/1.1 after H3 connection failure
+- Add README documentation for best-effort backendProtocol selection and supported protocol modes
+
 ## 2026-03-19 - 25.16.0 - feat(quic,http3)
 add HTTP/3 proxy handling and hot-reload QUIC TLS configuration
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@push.rocks/smartproxy",
-  "version": "25.16.0",
+  "version": "25.17.9",
   "private": false,
   "description": "A powerful proxy package with unified route-based configuration for high traffic management. Features include SSL/TLS support, flexible routing patterns, WebSocket handling, advanced security options, and automatic ACME certificate management.",
   "main": "dist_ts/index.js",

readme.md

@@ -328,6 +328,41 @@ const proxy = new SmartProxy({
 });
 ```
 
+### 🚄 Best-Effort Backend Protocol (H3 > H2 > H1)
+
+SmartProxy automatically uses the **highest protocol your backend supports** for HTTP requests. The backend protocol is independent of the client protocol — a client using HTTP/1.1 can be forwarded over HTTP/3 to the backend, and vice versa.
+
+```typescript
+const route: IRouteConfig = {
+  name: 'auto-protocol',
+  match: { ports: 443, domains: 'app.example.com' },
+  action: {
+    type: 'forward',
+    targets: [{ host: 'backend', port: 8443 }],
+    tls: { mode: 'terminate', certificate: 'auto' },
+    options: {
+      backendProtocol: 'auto'  // 👈 Default — best-effort selection
+    }
+  }
+};
+```
+
+**How protocol discovery works (browser model):**
+
+1. First request → TLS ALPN probe detects H2 or H1
+2. Backend response inspected for `Alt-Svc: h3=":port"` header
+3. If H3 advertised → cached and used for subsequent requests via QUIC
+4. Graceful fallback: H3 failure → H2 → H1 with automatic cache invalidation
+
+| `backendProtocol` | Behavior |
+|---|---|
+| `'auto'` (default) | Best-effort: H3 > H2 > H1 with Alt-Svc discovery |
+| `'http1'` | Always HTTP/1.1 |
+| `'http2'` | Always HTTP/2 (hard-fail if unsupported) |
+| `'http3'` | Always HTTP/3 via QUIC (hard-fail if unsupported) |
+
+> **Note:** WebSocket upgrades always use HTTP/1.1 to the backend regardless of `backendProtocol`, since there's no performance benefit from H2/H3 Extended CONNECT for tunneled connections, and backend support is rare.
+
 ### 🔁 Dual-Stack TCP + UDP Route
 
 Listen on both TCP and UDP with a single route — handle each transport with its own handler:
@@ -776,6 +811,28 @@ interface IRouteLoadBalancing {
 }
 ```
 
+### Backend Protocol Options
+
+```typescript
+// Set on action.options
+{
+  action: {
+    type: 'forward',
+    targets: [...],
+    options: {
+      backendProtocol: 'auto' | 'http1' | 'http2' | 'http3'
+    }
+  }
+}
+```
+
+| Value | Backend Behavior |
+|-------|-----------------|
+| `'auto'` | Best-effort: discovers H3 via Alt-Svc, probes H2 via ALPN, falls back to H1 |
+| `'http1'` | Always HTTP/1.1 (no ALPN probe) |
+| `'http2'` | Always HTTP/2 (hard-fail if handshake fails) |
+| `'http3'` | Always HTTP/3 over QUIC (3s connect timeout, hard-fail if unreachable) |
+
 ### UDP & QUIC Options
 
 ```typescript
@@ -1054,6 +1111,10 @@ SmartProxy searches for the Rust binary in this order:
 5. Local dev build (`./rust/target/release/rustproxy`)
 6. System PATH (`rustproxy`)
 
+### QUIC / HTTP3 Caveats
+- **GREASE frames are disabled.** The underlying h3 crate sends [GREASE frames](https://www.rfc-editor.org/rfc/rfc9114.html#frame-reserved) by default to test protocol extensibility. However, some HTTP/3 clients and servers don't properly ignore unknown frame types, causing 400/500 errors or stream hangs ([h3#206](https://github.com/hyperium/h3/issues/206)). SmartProxy disables GREASE on both the server side (for incoming H3 requests) and the client side (for H3 backend connections) to maximize compatibility.
+- **HTTP/3 is pre-release.** The h3 ecosystem (h3 0.0.8, h3-quinn 0.0.10, quinn 0.11) is still pre-1.0. Expect rough edges.
+
 ### Performance Tuning
 - ✅ Use NFTables forwarding for high-traffic routes (Linux only)
 - ✅ Enable connection keep-alive where appropriate

rust/Cargo.lock

@@ -1224,10 +1224,14 @@ dependencies = [
  "bytes",
  "clap",
  "dashmap",
+ "h3",
+ "h3-quinn",
+ "http",
  "http-body-util",
  "hyper",
  "hyper-util",
  "mimalloc",
+ "quinn",
  "rcgen",
  "rustls",
  "rustls-pemfile",

rust/crates/rustproxy-http/src/h3_service.rs

@@ -4,6 +4,7 @@
 //! and forwards them to backends using the same routing and pool infrastructure
 //! as the HTTP/1+2 proxy.
 
+use std::net::SocketAddr;
 use std::pin::Pin;
 use std::sync::Arc;
 use std::task::{Context, Poll};
@@ -35,7 +36,6 @@ pub struct H3ProxyService {
     protocol_cache: Arc<ProtocolCache>,
     #[allow(dead_code)]
     upstream_selector: UpstreamSelector,
-    #[allow(dead_code)]
     backend_tls_config: Arc<rustls::ClientConfig>,
     connect_timeout: Duration,
 }
@@ -61,17 +61,23 @@ impl H3ProxyService {
     }
 
     /// Handle an accepted QUIC connection as HTTP/3.
+    ///
+    /// If `real_client_addr` is provided (from PROXY protocol), it overrides
+    /// `connection.remote_address()` for client IP attribution.
     pub async fn handle_connection(
         &self,
         connection: quinn::Connection,
         _fallback_route: &RouteConfig,
         port: u16,
+        real_client_addr: Option<SocketAddr>,
     ) -> anyhow::Result<()> {
-        let remote_addr = connection.remote_address();
+        let remote_addr = real_client_addr.unwrap_or_else(|| connection.remote_address());
         debug!("HTTP/3 connection from {} on port {}", remote_addr, port);
 
         let mut h3_conn: h3::server::Connection<h3_quinn::Connection, Bytes> =
-            h3::server::Connection::new(h3_quinn::Connection::new(connection))
+            h3::server::builder()
+                .send_grease(false)
+                .build(h3_quinn::Connection::new(connection))
                 .await
                 .map_err(|e| anyhow::anyhow!("H3 connection setup failed: {}", e))?;
 
@@ -93,12 +99,14 @@ impl H3ProxyService {
                     let rm = self.route_manager.load();
                     let pool = Arc::clone(&self.connection_pool);
                     let metrics = Arc::clone(&self.metrics);
+                    let backend_tls = Arc::clone(&self.backend_tls_config);
                     let connect_timeout = self.connect_timeout;
                     let client_ip = client_ip.clone();
 
                     tokio::spawn(async move {
                         if let Err(e) = handle_h3_request(
-                            request, stream, port, &client_ip, &rm, &pool, &metrics, connect_timeout,
+                            request, stream, port, &client_ip, &rm, &pool, &metrics,
+                            &backend_tls, connect_timeout,
                         ).await {
                             debug!("HTTP/3 request error from {}: {}", client_ip, e);
                         }
@@ -128,16 +136,18 @@ async fn handle_h3_request(
     route_manager: &RouteManager,
     _connection_pool: &ConnectionPool,
     metrics: &MetricsCollector,
+    backend_tls_config: &Arc<rustls::ClientConfig>,
     connect_timeout: Duration,
 ) -> anyhow::Result<()> {
     let method = request.method().clone();
     let uri = request.uri().clone();
     let path = uri.path().to_string();
 
-    // Extract host from :authority or Host header
-    let host = request.uri().authority()
-        .map(|a| a.as_str().to_string())
-        .or_else(|| request.headers().get("host").and_then(|v| v.to_str().ok()).map(|s| s.to_string()))
+    // Extract host from :authority or Host header (strip port to match TCP/HTTP path)
+    let host = request.uri().host()
+        .map(|h| h.to_string())
+        .or_else(|| request.headers().get("host").and_then(|v| v.to_str().ok())
+            .map(|h| h.split(':').next().unwrap_or(h).to_string()))
         .unwrap_or_default();
 
     debug!("HTTP/3 {} {} (host: {}, client: {})", method, path, host, client_ip);
@@ -151,7 +161,8 @@ async fn handle_h3_request(
         tls_version: Some("TLSv1.3"),
         headers: None,
         is_tls: true,
-        protocol: Some("http"),
+        protocol: None,  // Don't filter on protocol — transport: Udp already excludes TCP routes,
+                         // and the route was already protocol-validated at the QUIC accept level.
         transport: Some(TransportProtocol::Udp),
     };
 
@@ -168,7 +179,15 @@ async fn handle_h3_request(
     let backend_port = target.port.resolve(port);
     let backend_addr = format!("{}:{}", backend_host, backend_port);
 
-    // Connect to backend via TCP HTTP/1.1 with timeout
+    // Determine if backend requires TLS (same logic as proxy_service.rs)
+    let mut use_tls = target.tls.is_some();
+    if let Some(ref tls) = route.action.tls {
+        if tls.mode == rustproxy_config::TlsMode::TerminateAndReencrypt {
+            use_tls = true;
+        }
+    }
+
+    // Connect to backend via TCP with timeout
     let tcp_stream = tokio::time::timeout(
         connect_timeout,
         tokio::net::TcpStream::connect(&backend_addr),
@@ -178,15 +197,27 @@ async fn handle_h3_request(
 
     let _ = tcp_stream.set_nodelay(true);
 
-    let io = hyper_util::rt::TokioIo::new(tcp_stream);
-    let (mut sender, conn) = hyper::client::conn::http1::handshake(io).await
-        .map_err(|e| anyhow::anyhow!("Backend handshake failed: {}", e))?;
-
-    tokio::spawn(async move {
-        if let Err(e) = conn.await {
-            debug!("Backend connection closed: {}", e);
-        }
-    });
+    // Branch: wrap in TLS if backend requires it, then HTTP/1.1 handshake.
+    // hyper's SendRequest<B> is NOT generic over the IO type, so both branches
+    // produce the same type and can be unified.
+    let mut sender = if use_tls {
+        let connector = tokio_rustls::TlsConnector::from(Arc::clone(backend_tls_config));
+        let server_name = rustls::pki_types::ServerName::try_from(backend_host.to_string())
+            .map_err(|e| anyhow::anyhow!("Invalid backend SNI '{}': {}", backend_host, e))?;
+        let tls_stream = connector.connect(server_name, tcp_stream).await
+            .map_err(|e| anyhow::anyhow!("Backend TLS handshake to {} failed: {}", backend_addr, e))?;
+        let io = hyper_util::rt::TokioIo::new(tls_stream);
+        let (sender, conn) = hyper::client::conn::http1::handshake(io).await
+            .map_err(|e| anyhow::anyhow!("Backend handshake failed: {}", e))?;
+        tokio::spawn(async move { let _ = conn.await; });
+        sender
+    } else {
+        let io = hyper_util::rt::TokioIo::new(tcp_stream);
+        let (sender, conn) = hyper::client::conn::http1::handshake(io).await
+            .map_err(|e| anyhow::anyhow!("Backend handshake failed: {}", e))?;
+        tokio::spawn(async move { let _ = conn.await; });
+        sender
+    };
 
     // Stream request body from H3 client to backend via an mpsc channel.
     // This avoids buffering the entire request body in memory.
@@ -209,7 +240,7 @@ async fn handle_h3_request(
 
     // Create a body that polls from the mpsc receiver
     let body = H3RequestBody { receiver: body_rx };
-    let backend_req = build_backend_request(&method, &backend_addr, &path, &host, &request, body)?;
+    let backend_req = build_backend_request(&method, &backend_addr, &path, &host, &request, body, use_tls)?;
 
     let response = sender.send_request(backend_req).await
         .map_err(|e| anyhow::anyhow!("Backend request failed: {}", e))?;
@@ -232,6 +263,12 @@ async fn handle_h3_request(
         h3_response = h3_response.header(name, value);
     }
 
+    // Extract content-length for body loop termination (must be before into_body())
+    let content_length: Option<u64> = response.headers()
+        .get(hyper::header::CONTENT_LENGTH)
+        .and_then(|v| v.to_str().ok())
+        .and_then(|s| s.parse().ok());
+
     // Add Alt-Svc for HTTP/3 advertisement
     let alt_svc = route.action.udp.as_ref()
         .and_then(|u| u.quic.as_ref())
@@ -252,21 +289,52 @@ async fn handle_h3_request(
 
     // Stream response body back
     use http_body_util::BodyExt;
+    use http_body::Body as _;
     let mut body = response.into_body();
     let mut total_bytes_out: u64 = 0;
-    while let Some(frame) = body.frame().await {
-        match frame {
-            Ok(frame) => {
+
+    // Per-frame idle timeout: if no frame arrives within this duration, assume
+    // the body is complete (or the backend has stalled). This prevents indefinite
+    // hangs on close-delimited bodies or when hyper's internal trailers oneshot
+    // never resolves after all data has been received.
+    const FRAME_IDLE_TIMEOUT: Duration = Duration::from_secs(30);
+
+    loop {
+        // Layer 1: If the body already knows it is finished (Content-Length
+        // bodies track remaining bytes internally), break immediately to
+        // avoid blocking on hyper's internal trailers oneshot.
+        if body.is_end_stream() {
+            break;
+        }
+
+        // Layer 3: Per-frame idle timeout safety net
+        match tokio::time::timeout(FRAME_IDLE_TIMEOUT, body.frame()).await {
+            Ok(Some(Ok(frame))) => {
                 if let Some(data) = frame.data_ref() {
                     total_bytes_out += data.len() as u64;
                     stream.send_data(Bytes::copy_from_slice(data)).await
                         .map_err(|e| anyhow::anyhow!("Failed to send H3 data: {}", e))?;
+
+                    // Layer 2: Content-Length byte count check
+                    if let Some(cl) = content_length {
+                        if total_bytes_out >= cl {
+                            break;
+                        }
+                    }
                 }
             }
-            Err(e) => {
+            Ok(Some(Err(e))) => {
                 warn!("Backend body read error: {}", e);
                 break;
             }
+            Ok(None) => break, // Body ended naturally
+            Err(_) => {
+                debug!(
+                    "H3 body frame idle timeout ({:?}) after {} bytes; finishing stream",
+                    FRAME_IDLE_TIMEOUT, total_bytes_out
+                );
+                break;
+            }
         }
     }
 
@@ -289,10 +357,12 @@ fn build_backend_request<B>(
     host: &str,
     original_request: &hyper::Request<()>,
     body: B,
+    use_tls: bool,
 ) -> anyhow::Result<hyper::Request<B>> {
+    let scheme = if use_tls { "https" } else { "http" };
     let mut req = hyper::Request::builder()
         .method(method)
-        .uri(format!("http://{}{}", backend_addr, path))
+        .uri(format!("{}://{}{}", scheme, backend_addr, path))
         .header("host", host);
 
     // Forward non-pseudo headers

rust/crates/rustproxy-http/src/proxy_service.rs

@@ -43,6 +43,10 @@ struct ConnActivity {
     /// increments on creation and decrements on Drop, keeping the watchdog aware that
     /// a response body is still streaming after the request handler has returned.
     active_requests: Option<Arc<AtomicU64>>,
+    /// Protocol cache key for Alt-Svc discovery. When set, `build_streaming_response`
+    /// checks the backend's original response headers for Alt-Svc before our
+    /// ResponseFilter injects its own. None when not in auto-detect mode or after H3 failure.
+    alt_svc_cache_key: Option<crate::protocol_cache::ProtocolCacheKey>,
 }
 
 /// Default upstream connect timeout (30 seconds).
@@ -341,7 +345,7 @@ impl HttpProxyService {
             let cn = cancel_inner.clone();
             let la = Arc::clone(&la_inner);
             let st = start;
-            let ca = ConnActivity { last_activity: Arc::clone(&la_inner), start, active_requests: Some(Arc::clone(&ar_inner)) };
+            let ca = ConnActivity { last_activity: Arc::clone(&la_inner), start, active_requests: Some(Arc::clone(&ar_inner)), alt_svc_cache_key: None };
             async move {
                 let result = svc.handle_request(req, peer, port, cn, ca).await;
                 // Mark request end — update activity timestamp before guard drops
@@ -418,7 +422,7 @@ impl HttpProxyService {
         peer_addr: std::net::SocketAddr,
         port: u16,
         cancel: CancellationToken,
-        conn_activity: ConnActivity,
+        mut conn_activity: ConnActivity,
     ) -> Result<Response<BoxBody<Bytes, hyper::Error>>, hyper::Error> {
         let host = req.headers()
             .get("host")
@@ -696,13 +700,19 @@ impl HttpProxyService {
         };
 
         // Derive legacy flags for the existing H1/H2 connection path
-        let (use_h2, needs_alpn_probe) = match &protocol_decision {
+        let (use_h2, mut needs_alpn_probe) = match &protocol_decision {
             ProtocolDecision::H1 => (false, false),
             ProtocolDecision::H2 => (true, false),
             ProtocolDecision::H3 { .. } => (false, false), // H3 path handled separately below
             ProtocolDecision::AlpnProbe => (false, true),
         };
 
+        // Set Alt-Svc cache key on conn_activity so build_streaming_response can check
+        // the backend's original Alt-Svc header before ResponseFilter injects our own.
+        if is_auto_detect_mode {
+            conn_activity.alt_svc_cache_key = Some(protocol_cache_key.clone());
+        }
+
         // --- H3 path: try QUIC connection before TCP ---
         if let ProtocolDecision::H3 { port: h3_port } = protocol_decision {
             let h3_pool_key = crate::connection_pool::PoolKey {
@@ -738,14 +748,15 @@ impl HttpProxyService {
                 Err(e) => {
                     warn!(backend = %upstream_key, error = %e,
                         "H3 backend connect failed, falling back to H2/H1");
-                    // Invalidate H3 from cache — next request will ALPN probe for H2/H1
-                    if is_auto_detect_mode {
-                        self.protocol_cache.insert(
-                            protocol_cache_key.clone(),
-                            crate::protocol_cache::DetectedProtocol::H1,
-                        );
+                    // Suppress Alt-Svc caching for the fallback to prevent re-caching H3
+                    // from our own injected Alt-Svc header or a stale backend Alt-Svc
+                    conn_activity.alt_svc_cache_key = None;
+                    // Force ALPN probe on TCP fallback so we correctly detect H2 vs H1
+                    // (don't cache anything yet — let the ALPN probe decide)
+                    if is_auto_detect_mode && upstream.use_tls {
+                        needs_alpn_probe = true;
                     }
-                    // Fall through to TCP path (ALPN probe for auto, or H1 for explicit)
+                    // Fall through to TCP path
                 }
             }
         }
@@ -945,18 +956,6 @@ impl HttpProxyService {
         self.upstream_selector.connection_ended(&upstream_key);
         self.metrics.backend_connection_closed(&upstream_key);
 
-        // --- Alt-Svc discovery: check if backend advertises H3 ---
-        if is_auto_detect_mode {
-            if let Ok(ref resp) = result {
-                if let Some(alt_svc) = resp.headers().get("alt-svc").and_then(|v| v.to_str().ok()) {
-                    if let Some(h3_port) = parse_alt_svc_h3_port(alt_svc) {
-                        debug!(backend = %upstream_key, h3_port, "Backend advertises H3 via Alt-Svc");
-                        self.protocol_cache.insert_h3(protocol_cache_key, h3_port);
-                    }
-                }
-            }
-        }
-
         result
     }
 
@@ -1755,6 +1754,19 @@ impl HttpProxyService {
     ) -> Result<Response<BoxBody<Bytes, hyper::Error>>, hyper::Error> {
         let (resp_parts, resp_body) = upstream_response.into_parts();
 
+        // Check for Alt-Svc in the backend's ORIGINAL response headers BEFORE
+        // ResponseFilter::apply_headers runs — the filter may inject our own Alt-Svc
+        // for client-facing HTTP/3 advertisement, which must not be confused with
+        // backend-originated Alt-Svc.
+        if let Some(ref cache_key) = conn_activity.alt_svc_cache_key {
+            if let Some(alt_svc) = resp_parts.headers.get("alt-svc").and_then(|v| v.to_str().ok()) {
+                if let Some(h3_port) = parse_alt_svc_h3_port(alt_svc) {
+                    debug!(h3_port, "Backend advertises H3 via Alt-Svc");
+                    self.protocol_cache.insert_h3(cache_key.clone(), h3_port);
+                }
+            }
+        }
+
         let mut response = Response::builder()
             .status(resp_parts.status);
 
@@ -2538,7 +2550,11 @@ impl HttpProxyService {
         backend_key: &str,
     ) -> Result<Response<BoxBody<Bytes, hyper::Error>>, hyper::Error> {
         let h3_quinn_conn = h3_quinn::Connection::new(quic_conn.clone());
-        let (mut driver, mut send_request) = match h3::client::new(h3_quinn_conn).await {
+        let (mut driver, mut send_request) = match h3::client::builder()
+            .send_grease(false)
+            .build(h3_quinn_conn)
+            .await
+        {
             Ok(pair) => pair,
             Err(e) => {
                 error!(backend = %backend_key, domain = %domain, error = %e, "H3 client handshake failed");

rust/crates/rustproxy-passthrough/src/quic_handler.rs

@@ -3,13 +3,21 @@
 //! Manages QUIC endpoints (via quinn), accepts connections, and either:
 //! - Forwards streams bidirectionally to TCP backends (QUIC termination)
 //! - Dispatches to H3ProxyService for HTTP/3 handling (Phase 5)
+//!
+//! When `proxy_ips` is configured, a UDP relay layer intercepts PROXY protocol v2
+//! headers before they reach quinn, extracting real client IPs for attribution.
 
-use std::net::SocketAddr;
+use std::net::{IpAddr, SocketAddr};
+use std::sync::atomic::{AtomicU64, Ordering};
 use std::sync::Arc;
+use std::time::Instant;
 
 use tokio::io::AsyncWriteExt;
+use tokio::net::UdpSocket;
+use tokio::task::JoinHandle;
 
 use arc_swap::ArcSwap;
+use dashmap::DashMap;
 use quinn::{Endpoint, ServerConfig as QuinnServerConfig};
 use rustls::ServerConfig as RustlsServerConfig;
 use tokio_util::sync::CancellationToken;
@@ -47,9 +55,274 @@ pub fn create_quic_endpoint(
     Ok(endpoint)
 }
 
+// ===== PROXY protocol relay for QUIC =====
+
+/// Result of creating a QUIC endpoint with a PROXY protocol relay layer.
+pub struct QuicProxyRelay {
+    /// The quinn endpoint (bound to 127.0.0.1:ephemeral).
+    pub endpoint: Endpoint,
+    /// The relay recv loop task handle.
+    pub relay_task: JoinHandle<()>,
+    /// Maps relay socket local addr → real client SocketAddr (from PROXY v2).
+    /// Consulted by `quic_accept_loop` to resolve real client IPs.
+    pub real_client_map: Arc<DashMap<SocketAddr, SocketAddr>>,
+}
+
+/// A single relay session for forwarding datagrams between an external source
+/// and the internal quinn endpoint.
+struct RelaySession {
+    socket: Arc<UdpSocket>,
+    last_activity: AtomicU64,
+    return_task: JoinHandle<()>,
+    cancel: CancellationToken,
+}
+
+/// Create a QUIC endpoint with a PROXY protocol v2 relay layer.
+///
+/// Instead of giving the external socket to quinn, we:
+/// 1. Bind a raw UDP socket on 0.0.0.0:port (external)
+/// 2. Bind quinn on 127.0.0.1:0 (internal, ephemeral)
+/// 3. Run a relay loop that filters PROXY v2 headers and forwards datagrams
+///
+/// Only used when `proxy_ips` is non-empty.
+pub fn create_quic_endpoint_with_proxy_relay(
+    port: u16,
+    tls_config: Arc<RustlsServerConfig>,
+    proxy_ips: Arc<Vec<IpAddr>>,
+    cancel: CancellationToken,
+) -> anyhow::Result<QuicProxyRelay> {
+    // Bind external socket on the real port
+    let external_socket = std::net::UdpSocket::bind(SocketAddr::from(([0, 0, 0, 0], port)))?;
+    external_socket.set_nonblocking(true)?;
+    let external_socket = Arc::new(
+        UdpSocket::from_std(external_socket)
+            .map_err(|e| anyhow::anyhow!("Failed to wrap external socket: {}", e))?,
+    );
+
+    // Bind quinn on localhost ephemeral port
+    let internal_socket = std::net::UdpSocket::bind("127.0.0.1:0")?;
+    let quinn_internal_addr = internal_socket.local_addr()?;
+
+    let quic_crypto = quinn::crypto::rustls::QuicServerConfig::try_from(tls_config)
+        .map_err(|e| anyhow::anyhow!("Failed to create QUIC crypto config: {}", e))?;
+    let server_config = QuinnServerConfig::with_crypto(Arc::new(quic_crypto));
+
+    let endpoint = Endpoint::new(
+        quinn::EndpointConfig::default(),
+        Some(server_config),
+        internal_socket,
+        quinn::default_runtime()
+            .ok_or_else(|| anyhow::anyhow!("No async runtime for quinn"))?,
+    )?;
+
+    let real_client_map = Arc::new(DashMap::new());
+
+    let relay_task = tokio::spawn(quic_proxy_relay_loop(
+        external_socket,
+        quinn_internal_addr,
+        proxy_ips,
+        Arc::clone(&real_client_map),
+        cancel,
+    ));
+
+    info!("QUIC endpoint with PROXY relay on port {} (quinn internal: {})", port, quinn_internal_addr);
+    Ok(QuicProxyRelay { endpoint, relay_task, real_client_map })
+}
+
+/// Main relay loop: reads datagrams from the external socket, filters PROXY v2
+/// headers from trusted proxy IPs, and forwards everything else to quinn via
+/// per-session relay sockets.
+async fn quic_proxy_relay_loop(
+    external_socket: Arc<UdpSocket>,
+    quinn_internal_addr: SocketAddr,
+    proxy_ips: Arc<Vec<IpAddr>>,
+    real_client_map: Arc<DashMap<SocketAddr, SocketAddr>>,
+    cancel: CancellationToken,
+) {
+    // Maps external source addr → real client addr (from PROXY v2 headers)
+    let proxy_addr_map: DashMap<SocketAddr, SocketAddr> = DashMap::new();
+    // Maps external source addr → relay session
+    let relay_sessions: DashMap<SocketAddr, Arc<RelaySession>> = DashMap::new();
+    let epoch = Instant::now();
+    let mut buf = vec![0u8; 65535];
+
+    // Inline cleanup: periodically scan relay_sessions for stale entries
+    let mut last_cleanup = Instant::now();
+    let cleanup_interval = std::time::Duration::from_secs(30);
+    let session_timeout_ms: u64 = 120_000;
+
+    loop {
+        let (len, src_addr) = tokio::select! {
+            _ = cancel.cancelled() => {
+                debug!("QUIC proxy relay loop cancelled");
+                break;
+            }
+            result = external_socket.recv_from(&mut buf) => {
+                match result {
+                    Ok(r) => r,
+                    Err(e) => {
+                        warn!("QUIC proxy relay recv error: {}", e);
+                        continue;
+                    }
+                }
+            }
+        };
+
+        let datagram = &buf[..len];
+
+        // PROXY v2 handling: only on first datagram from a trusted proxy IP
+        // (before a relay session exists for this source)
+        if proxy_ips.contains(&src_addr.ip()) && relay_sessions.get(&src_addr).is_none() {
+            if crate::proxy_protocol::is_proxy_protocol_v2(datagram) {
+                match crate::proxy_protocol::parse_v2(datagram) {
+                    Ok((header, _consumed)) => {
+                        debug!("QUIC PROXY v2 from {}: real client {}", src_addr, header.source_addr);
+                        proxy_addr_map.insert(src_addr, header.source_addr);
+                        continue; // consume the PROXY v2 datagram
+                    }
+                    Err(e) => {
+                        debug!("QUIC proxy relay: failed to parse PROXY v2 from {}: {}", src_addr, e);
+                    }
+                }
+            }
+        }
+
+        // Determine real client address
+        let real_client = proxy_addr_map.get(&src_addr)
+            .map(|r| *r)
+            .unwrap_or(src_addr);
+
+        // Get or create relay session for this external source
+        let session = match relay_sessions.get(&src_addr) {
+            Some(s) => {
+                s.last_activity.store(epoch.elapsed().as_millis() as u64, Ordering::Relaxed);
+                Arc::clone(s.value())
+            }
+            None => {
+                // Create new relay socket connected to quinn's internal address
+                let relay_socket = match UdpSocket::bind("127.0.0.1:0").await {
+                    Ok(s) => s,
+                    Err(e) => {
+                        warn!("QUIC relay: failed to bind relay socket: {}", e);
+                        continue;
+                    }
+                };
+                if let Err(e) = relay_socket.connect(quinn_internal_addr).await {
+                    warn!("QUIC relay: failed to connect relay socket to {}: {}", quinn_internal_addr, e);
+                    continue;
+                }
+                let relay_local_addr = match relay_socket.local_addr() {
+                    Ok(a) => a,
+                    Err(e) => {
+                        warn!("QUIC relay: failed to get relay socket local addr: {}", e);
+                        continue;
+                    }
+                };
+                let relay_socket = Arc::new(relay_socket);
+
+                // Store the real client mapping for the QUIC accept loop
+                real_client_map.insert(relay_local_addr, real_client);
+
+                // Spawn return-path relay: quinn -> external socket -> original source
+                let session_cancel = cancel.child_token();
+                let return_task = tokio::spawn(relay_return_path(
+                    Arc::clone(&relay_socket),
+                    Arc::clone(&external_socket),
+                    src_addr,
+                    session_cancel.child_token(),
+                ));
+
+                let session = Arc::new(RelaySession {
+                    socket: relay_socket,
+                    last_activity: AtomicU64::new(epoch.elapsed().as_millis() as u64),
+                    return_task,
+                    cancel: session_cancel,
+                });
+
+                relay_sessions.insert(src_addr, Arc::clone(&session));
+                debug!("QUIC relay: new session for {} (relay {}), real client {}",
+                    src_addr, relay_local_addr, real_client);
+
+                session
+            }
+        };
+
+        // Forward datagram to quinn via the relay socket
+        if let Err(e) = session.socket.send(datagram).await {
+            debug!("QUIC relay: forward error to quinn for {}: {}", src_addr, e);
+        }
+
+        // Periodic cleanup of stale relay sessions
+        if last_cleanup.elapsed() >= cleanup_interval {
+            last_cleanup = Instant::now();
+            let now_ms = epoch.elapsed().as_millis() as u64;
+            let stale_keys: Vec<SocketAddr> = relay_sessions.iter()
+                .filter(|entry| {
+                    let age = now_ms.saturating_sub(entry.value().last_activity.load(Ordering::Relaxed));
+                    age > session_timeout_ms
+                })
+                .map(|entry| *entry.key())
+                .collect();
+
+            for key in stale_keys {
+                if let Some((_, session)) = relay_sessions.remove(&key) {
+                    session.cancel.cancel();
+                    session.return_task.abort();
+                    // Clean up real_client_map entry
+                    if let Ok(addr) = session.socket.local_addr() {
+                        real_client_map.remove(&addr);
+                    }
+                    proxy_addr_map.remove(&key);
+                    debug!("QUIC relay: cleaned up stale session for {}", key);
+                }
+            }
+        }
+    }
+
+    // Shutdown: cancel all relay sessions
+    for entry in relay_sessions.iter() {
+        entry.value().cancel.cancel();
+        entry.value().return_task.abort();
+    }
+}
+
+/// Return-path relay: receives datagrams from quinn (via the relay socket)
+/// and forwards them back to the external client through the external socket.
+async fn relay_return_path(
+    relay_socket: Arc<UdpSocket>,
+    external_socket: Arc<UdpSocket>,
+    external_src_addr: SocketAddr,
+    cancel: CancellationToken,
+) {
+    let mut buf = vec![0u8; 65535];
+    loop {
+        let len = tokio::select! {
+            _ = cancel.cancelled() => break,
+            result = relay_socket.recv(&mut buf) => {
+                match result {
+                    Ok(len) => len,
+                    Err(e) => {
+                        debug!("QUIC relay return recv error for {}: {}", external_src_addr, e);
+                        break;
+                    }
+                }
+            }
+        };
+
+        if let Err(e) = external_socket.send_to(&buf[..len], external_src_addr).await {
+            debug!("QUIC relay return send error to {}: {}", external_src_addr, e);
+            break;
+        }
+    }
+}
+
+// ===== QUIC accept loop =====
+
 /// Run the QUIC accept loop for a single endpoint.
 ///
 /// Accepts incoming QUIC connections and spawns a task per connection.
+/// When `real_client_map` is provided, it is consulted to resolve real client
+/// IPs from PROXY protocol v2 headers (relay socket addr → real client addr).
 pub async fn quic_accept_loop(
     endpoint: Endpoint,
     port: u16,
@@ -58,6 +331,7 @@ pub async fn quic_accept_loop(
     conn_tracker: Arc<ConnectionTracker>,
     cancel: CancellationToken,
     h3_service: Option<Arc<H3ProxyService>>,
+    real_client_map: Option<Arc<DashMap<SocketAddr, SocketAddr>>>,
 ) {
     loop {
         let incoming = tokio::select! {
@@ -77,11 +351,16 @@ pub async fn quic_accept_loop(
         };
 
         let remote_addr = incoming.remote_address();
-        let ip = remote_addr.ip();
+
+        // Resolve real client IP from PROXY protocol map if available
+        let real_addr = real_client_map.as_ref()
+            .and_then(|map| map.get(&remote_addr).map(|r| *r))
+            .unwrap_or(remote_addr);
+        let ip = real_addr.ip();
 
         // Per-IP rate limiting
         if !conn_tracker.try_accept(&ip) {
-            debug!("QUIC connection rejected from {} (rate limit)", remote_addr);
+            debug!("QUIC connection rejected from {} (rate limit)", real_addr);
             // Drop `incoming` to refuse the connection
             continue;
         }
@@ -104,7 +383,7 @@ pub async fn quic_accept_loop(
         let route = match rm.find_route(&ctx) {
             Some(m) => m.route.clone(),
             None => {
-                debug!("No QUIC route matched for port {} from {}", port, remote_addr);
+                debug!("No QUIC route matched for port {} from {}", port, real_addr);
                 continue;
             }
         };
@@ -117,11 +396,12 @@ pub async fn quic_accept_loop(
         let conn_tracker = Arc::clone(&conn_tracker);
         let cancel = cancel.child_token();
         let h3_svc = h3_service.clone();
+        let real_client_addr = if real_addr != remote_addr { Some(real_addr) } else { None };
 
         tokio::spawn(async move {
-            match handle_quic_connection(incoming, route, port, Arc::clone(&metrics), &cancel, h3_svc).await {
-                Ok(()) => debug!("QUIC connection from {} completed", remote_addr),
-                Err(e) => debug!("QUIC connection from {} error: {}", remote_addr, e),
+            match handle_quic_connection(incoming, route, port, Arc::clone(&metrics), &cancel, h3_svc, real_client_addr).await {
+                Ok(()) => debug!("QUIC connection from {} completed", real_addr),
+                Err(e) => debug!("QUIC connection from {} error: {}", real_addr, e),
             }
 
             // Cleanup
@@ -144,10 +424,11 @@ async fn handle_quic_connection(
     metrics: Arc<MetricsCollector>,
     cancel: &CancellationToken,
     h3_service: Option<Arc<H3ProxyService>>,
+    real_client_addr: Option<SocketAddr>,
 ) -> anyhow::Result<()> {
     let connection = incoming.await?;
-    let remote_addr = connection.remote_address();
-    debug!("QUIC connection established from {}", remote_addr);
+    let effective_addr = real_client_addr.unwrap_or_else(|| connection.remote_address());
+    debug!("QUIC connection established from {}", effective_addr);
 
     // Check if this route has HTTP/3 enabled
     let enable_http3 = route.action.udp.as_ref()
@@ -158,7 +439,7 @@ async fn handle_quic_connection(
     if enable_http3 {
         if let Some(ref h3_svc) = h3_service {
             debug!("HTTP/3 enabled for route {:?}, dispatching to H3ProxyService", route.name);
-            h3_svc.handle_connection(connection, &route, port).await
+            h3_svc.handle_connection(connection, &route, port, real_client_addr).await
         } else {
             warn!("HTTP/3 enabled for route {:?} but H3ProxyService not initialized", route.name);
             // Keep connection alive until cancelled
@@ -172,7 +453,7 @@ async fn handle_quic_connection(
         }
     } else {
         // Non-HTTP3 QUIC: bidirectional stream forwarding to TCP backend
-        handle_quic_stream_forwarding(connection, route, port, metrics, cancel).await
+        handle_quic_stream_forwarding(connection, route, port, metrics, cancel, real_client_addr).await
     }
 }
 
@@ -187,8 +468,9 @@ async fn handle_quic_stream_forwarding(
     port: u16,
     metrics: Arc<MetricsCollector>,
     cancel: &CancellationToken,
+    real_client_addr: Option<SocketAddr>,
 ) -> anyhow::Result<()> {
-    let remote_addr = connection.remote_address();
+    let effective_addr = real_client_addr.unwrap_or_else(|| connection.remote_address());
     let route_id = route.name.as_deref().or(route.id.as_deref());
     let metrics_arc = metrics;
 
@@ -209,7 +491,7 @@ async fn handle_quic_stream_forwarding(
                     Err(quinn::ConnectionError::ApplicationClosed(_)) => break,
                     Err(quinn::ConnectionError::LocallyClosed) => break,
                     Err(e) => {
-                        debug!("QUIC stream accept error from {}: {}", remote_addr, e);
+                        debug!("QUIC stream accept error from {}: {}", effective_addr, e);
                         break;
                     }
                 }
@@ -217,7 +499,7 @@ async fn handle_quic_stream_forwarding(
         };
 
         let backend_addr = backend_addr.clone();
-        let ip_str = remote_addr.ip().to_string();
+        let ip_str = effective_addr.ip().to_string();
         let stream_metrics = Arc::clone(&metrics_arc);
         let stream_route_id = route_id.map(|s| s.to_string());
 

rust/crates/rustproxy-passthrough/src/udp_listener.rs

@@ -2,12 +2,17 @@
 //!
 //! Binds UDP sockets on configured ports, receives datagrams, matches routes,
 //! tracks sessions (flows), and forwards datagrams to backend UDP sockets.
+//!
+//! Supports PROXY protocol v2 on both raw UDP and QUIC paths when `proxy_ips`
+//! is configured. For QUIC, a relay layer intercepts datagrams before they
+//! reach the quinn endpoint.
 
 use std::collections::HashMap;
-use std::net::SocketAddr;
+use std::net::{IpAddr, SocketAddr};
 use std::sync::atomic::Ordering;
 use std::sync::Arc;
 
+use dashmap::DashMap;
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 
 use arc_swap::ArcSwap;
@@ -48,6 +53,9 @@ pub struct UdpListenerManager {
     relay_reader_cancel: Option<CancellationToken>,
     /// H3 proxy service for HTTP/3 request handling
     h3_service: Option<Arc<H3ProxyService>>,
+    /// Trusted proxy IPs that may send PROXY protocol v2 headers.
+    /// When non-empty, PROXY v2 detection is enabled on both raw UDP and QUIC paths.
+    proxy_ips: Arc<Vec<IpAddr>>,
 }
 
 impl Drop for UdpListenerManager {
@@ -80,9 +88,18 @@ impl UdpListenerManager {
             relay_writer: Arc::new(Mutex::new(None)),
             relay_reader_cancel: None,
             h3_service: None,
+            proxy_ips: Arc::new(Vec::new()),
         }
     }
 
+    /// Set the trusted proxy IPs for PROXY protocol v2 detection.
+    pub fn set_proxy_ips(&mut self, ips: Vec<IpAddr>) {
+        if !ips.is_empty() {
+            info!("UDP/QUIC PROXY protocol v2 enabled for {} trusted IPs", ips.len());
+        }
+        self.proxy_ips = Arc::new(ips);
+    }
+
     /// Set the H3 proxy service for HTTP/3 request handling.
     pub fn set_h3_service(&mut self, svc: Arc<H3ProxyService>) {
         self.h3_service = Some(svc);
@@ -122,20 +139,44 @@ impl UdpListenerManager {
 
         if has_quic {
             if let Some(tls) = tls_config {
-                // Create QUIC endpoint; clone it so we can hot-swap TLS later
-                let endpoint = crate::quic_handler::create_quic_endpoint(port, tls)?;
-                let endpoint_for_updates = endpoint.clone(); // quinn::Endpoint is Arc-based
-                let handle = tokio::spawn(crate::quic_handler::quic_accept_loop(
-                    endpoint,
-                    port,
-                    Arc::clone(&self.route_manager),
-                    Arc::clone(&self.metrics),
-                    Arc::clone(&self.conn_tracker),
-                    self.cancel_token.child_token(),
-                    self.h3_service.clone(),
-                ));
-                self.listeners.insert(port, (handle, Some(endpoint_for_updates)));
-                info!("QUIC endpoint started on port {}", port);
+                if self.proxy_ips.is_empty() {
+                    // Direct path: quinn owns the external socket (zero overhead)
+                    let endpoint = crate::quic_handler::create_quic_endpoint(port, tls)?;
+                    let endpoint_for_updates = endpoint.clone();
+                    let handle = tokio::spawn(crate::quic_handler::quic_accept_loop(
+                        endpoint,
+                        port,
+                        Arc::clone(&self.route_manager),
+                        Arc::clone(&self.metrics),
+                        Arc::clone(&self.conn_tracker),
+                        self.cancel_token.child_token(),
+                        self.h3_service.clone(),
+                        None,
+                    ));
+                    self.listeners.insert(port, (handle, Some(endpoint_for_updates)));
+                    info!("QUIC endpoint started on port {}", port);
+                } else {
+                    // Proxy relay path: we own external socket, quinn on localhost
+                    let relay = crate::quic_handler::create_quic_endpoint_with_proxy_relay(
+                        port,
+                        tls,
+                        Arc::clone(&self.proxy_ips),
+                        self.cancel_token.child_token(),
+                    )?;
+                    let endpoint_for_updates = relay.endpoint.clone();
+                    let handle = tokio::spawn(crate::quic_handler::quic_accept_loop(
+                        relay.endpoint,
+                        port,
+                        Arc::clone(&self.route_manager),
+                        Arc::clone(&self.metrics),
+                        Arc::clone(&self.conn_tracker),
+                        self.cancel_token.child_token(),
+                        self.h3_service.clone(),
+                        Some(relay.real_client_map),
+                    ));
+                    self.listeners.insert(port, (handle, Some(endpoint_for_updates)));
+                    info!("QUIC endpoint with PROXY relay started on port {}", port);
+                }
                 return Ok(());
             } else {
                 warn!("QUIC routes on port {} but no TLS config provided, falling back to raw UDP", port);
@@ -158,6 +199,7 @@ impl UdpListenerManager {
             Arc::clone(&self.datagram_handler_relay),
             Arc::clone(&self.relay_writer),
             self.cancel_token.child_token(),
+            Arc::clone(&self.proxy_ips),
         ));
 
         self.listeners.insert(port, (handle, None));
@@ -222,6 +264,149 @@ impl UdpListenerManager {
         }
     }
 
+    /// Upgrade raw UDP fallback listeners to QUIC endpoints.
+    ///
+    /// At startup, if no TLS certs are available, QUIC routes fall back to raw UDP.
+    /// When certs become available later (via loadCertificate IPC or ACME), this method
+    /// stops the raw UDP listener, drains sessions, and creates a proper QUIC endpoint.
+    ///
+    /// This is idempotent — ports that already have QUIC endpoints are skipped.
+    pub async fn upgrade_raw_to_quic(&mut self, tls_config: Arc<rustls::ServerConfig>) {
+        // Find ports that are raw UDP fallback (endpoint=None) but have QUIC routes
+        let rm = self.route_manager.load();
+        let upgrade_ports: Vec<u16> = self.listeners.iter()
+            .filter(|(_, (_, endpoint))| endpoint.is_none())
+            .filter(|(port, _)| {
+                rm.routes_for_port(**port).iter().any(|r| {
+                    r.action.udp.as_ref()
+                        .and_then(|u| u.quic.as_ref())
+                        .is_some()
+                })
+            })
+            .map(|(port, _)| *port)
+            .collect();
+
+        for port in upgrade_ports {
+            info!("Upgrading raw UDP listener on port {} to QUIC endpoint", port);
+
+            // Stop the raw UDP listener task and drain sessions to release the socket
+            if let Some((handle, _)) = self.listeners.remove(&port) {
+                handle.abort();
+            }
+            let drained = self.session_table.drain_port(
+                port, &self.metrics, &self.conn_tracker,
+            );
+            if drained > 0 {
+                debug!("Drained {} UDP sessions on port {} for QUIC upgrade", drained, port);
+            }
+
+            // Brief yield to let aborted tasks drop their socket references
+            tokio::task::yield_now().await;
+
+            // Create QUIC endpoint on the now-free port
+            let create_result = if self.proxy_ips.is_empty() {
+                self.create_quic_direct(port, Arc::clone(&tls_config))
+            } else {
+                self.create_quic_with_relay(port, Arc::clone(&tls_config))
+            };
+
+            match create_result {
+                Ok(()) => {
+                    info!("QUIC endpoint started on port {} (upgraded from raw UDP)", port);
+                }
+                Err(e) => {
+                    // Port may still be held — retry once after a brief delay
+                    warn!("QUIC endpoint creation failed on port {}, retrying: {}", port, e);
+                    tokio::time::sleep(std::time::Duration::from_millis(50)).await;
+
+                    let retry_result = if self.proxy_ips.is_empty() {
+                        self.create_quic_direct(port, Arc::clone(&tls_config))
+                    } else {
+                        self.create_quic_with_relay(port, Arc::clone(&tls_config))
+                    };
+
+                    match retry_result {
+                        Ok(()) => {
+                            info!("QUIC endpoint started on port {} (upgraded from raw UDP, retry)", port);
+                        }
+                        Err(e2) => {
+                            error!("Failed to upgrade port {} to QUIC after retry: {}. \
+                                   Rebinding as raw UDP.", port, e2);
+                            // Fallback: rebind as raw UDP so the port isn't dead
+                            if let Ok(()) = self.rebind_raw_udp(port).await {
+                                warn!("Port {} rebound as raw UDP (QUIC upgrade failed)", port);
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    /// Create a direct QUIC endpoint (quinn owns the socket).
+    fn create_quic_direct(&mut self, port: u16, tls_config: Arc<rustls::ServerConfig>) -> anyhow::Result<()> {
+        let endpoint = crate::quic_handler::create_quic_endpoint(port, tls_config)?;
+        let endpoint_for_updates = endpoint.clone();
+        let handle = tokio::spawn(crate::quic_handler::quic_accept_loop(
+            endpoint,
+            port,
+            Arc::clone(&self.route_manager),
+            Arc::clone(&self.metrics),
+            Arc::clone(&self.conn_tracker),
+            self.cancel_token.child_token(),
+            self.h3_service.clone(),
+            None,
+        ));
+        self.listeners.insert(port, (handle, Some(endpoint_for_updates)));
+        Ok(())
+    }
+
+    /// Create a QUIC endpoint with PROXY protocol relay.
+    fn create_quic_with_relay(&mut self, port: u16, tls_config: Arc<rustls::ServerConfig>) -> anyhow::Result<()> {
+        let relay = crate::quic_handler::create_quic_endpoint_with_proxy_relay(
+            port,
+            tls_config,
+            Arc::clone(&self.proxy_ips),
+            self.cancel_token.child_token(),
+        )?;
+        let endpoint_for_updates = relay.endpoint.clone();
+        let handle = tokio::spawn(crate::quic_handler::quic_accept_loop(
+            relay.endpoint,
+            port,
+            Arc::clone(&self.route_manager),
+            Arc::clone(&self.metrics),
+            Arc::clone(&self.conn_tracker),
+            self.cancel_token.child_token(),
+            self.h3_service.clone(),
+            Some(relay.real_client_map),
+        ));
+        self.listeners.insert(port, (handle, Some(endpoint_for_updates)));
+        Ok(())
+    }
+
+    /// Rebind a port as a raw UDP listener (fallback when QUIC upgrade fails).
+    async fn rebind_raw_udp(&mut self, port: u16) -> anyhow::Result<()> {
+        let addr: std::net::SocketAddr = ([0, 0, 0, 0], port).into();
+        let socket = UdpSocket::bind(addr).await?;
+        let socket = Arc::new(socket);
+
+        let handle = tokio::spawn(Self::recv_loop(
+            socket,
+            port,
+            Arc::clone(&self.route_manager),
+            Arc::clone(&self.metrics),
+            Arc::clone(&self.conn_tracker),
+            Arc::clone(&self.session_table),
+            Arc::clone(&self.datagram_handler_relay),
+            Arc::clone(&self.relay_writer),
+            self.cancel_token.child_token(),
+            Arc::clone(&self.proxy_ips),
+        ));
+
+        self.listeners.insert(port, (handle, None));
+        Ok(())
+    }
+
     /// Set the datagram handler relay socket path and establish connection.
     pub async fn set_datagram_handler_relay(&mut self, path: String) {
         // Cancel previous relay reader task if any
@@ -296,6 +481,10 @@ impl UdpListenerManager {
     }
 
     /// Main receive loop for a UDP port.
+    ///
+    /// When `proxy_ips` is non-empty, the first datagram from a trusted proxy IP
+    /// is checked for PROXY protocol v2. If found, the real client IP is extracted
+    /// and used for all subsequent session handling for that source address.
     async fn recv_loop(
         socket: Arc<UdpSocket>,
         port: u16,
@@ -306,10 +495,15 @@ impl UdpListenerManager {
         _datagram_handler_relay: Arc<RwLock<Option<String>>>,
         relay_writer: Arc<Mutex<Option<tokio::net::unix::OwnedWriteHalf>>>,
         cancel: CancellationToken,
+        proxy_ips: Arc<Vec<IpAddr>>,
     ) {
         // Use a reasonably large buffer; actual max is per-route but we need a single buffer
         let mut buf = vec![0u8; 65535];
 
+        // Maps proxy source addr → real client addr (from PROXY v2 headers).
+        // Only populated when proxy_ips is non-empty.
+        let proxy_addr_map: DashMap<SocketAddr, SocketAddr> = DashMap::new();
+
         loop {
             let (len, client_addr) = tokio::select! {
                 _ = cancel.cancelled() => {
@@ -329,9 +523,39 @@ impl UdpListenerManager {
 
             let datagram = &buf[..len];
 
-            // Route matching
+            // PROXY protocol v2 detection for datagrams from trusted proxy IPs
+            let effective_client_ip = if !proxy_ips.is_empty() && proxy_ips.contains(&client_addr.ip()) {
+                let session_key: SessionKey = (client_addr, port);
+                if session_table.get(&session_key).is_none() && !proxy_addr_map.contains_key(&client_addr) {
+                    // No session and no prior PROXY header — check for PROXY v2
+                    if crate::proxy_protocol::is_proxy_protocol_v2(datagram) {
+                        match crate::proxy_protocol::parse_v2(datagram) {
+                            Ok((header, _consumed)) => {
+                                debug!("UDP PROXY v2 from {}: real client {}", client_addr, header.source_addr);
+                                proxy_addr_map.insert(client_addr, header.source_addr);
+                                continue; // discard the PROXY v2 datagram
+                            }
+                            Err(e) => {
+                                debug!("UDP PROXY v2 parse error from {}: {}", client_addr, e);
+                                client_addr.ip()
+                            }
+                        }
+                    } else {
+                        client_addr.ip()
+                    }
+                } else {
+                    // Use real client IP if we've previously seen a PROXY v2 header
+                    proxy_addr_map.get(&client_addr)
+                        .map(|r| r.ip())
+                        .unwrap_or_else(|| client_addr.ip())
+                }
+            } else {
+                client_addr.ip()
+            };
+
+            // Route matching — use effective (real) client IP
             let rm = route_manager.load();
-            let ip_str = client_addr.ip().to_string();
+            let ip_str = effective_client_ip.to_string();
             let ctx = MatchContext {
                 port,
                 domain: None,
@@ -380,20 +604,21 @@ impl UdpListenerManager {
             }
 
             // Session lookup or create
+            // Session key uses the proxy's source addr for correct return-path routing
             let session_key: SessionKey = (client_addr, port);
             let session = match session_table.get(&session_key) {
                 Some(s) => s,
                 None => {
-                    // New session — check per-IP limits
-                    if !conn_tracker.try_accept(&client_addr.ip()) {
-                        debug!("UDP session rejected for {} (rate limit)", client_addr);
+                    // New session — check per-IP limits using the real client IP
+                    if !conn_tracker.try_accept(&effective_client_ip) {
+                        debug!("UDP session rejected for {} (rate limit)", effective_client_ip);
                         continue;
                     }
                     if !session_table.can_create_session(
-                        &client_addr.ip(),
+                        &effective_client_ip,
                         udp_config.max_sessions_per_ip,
                     ) {
-                        debug!("UDP session rejected for {} (per-IP session limit)", client_addr);
+                        debug!("UDP session rejected for {} (per-IP session limit)", effective_client_ip);
                         continue;
                     }
 
@@ -426,8 +651,8 @@ impl UdpListenerManager {
                     }
                     let backend_socket = Arc::new(backend_socket);
 
-                    debug!("New UDP session: {} -> {} (via port {})",
-                        client_addr, backend_addr, port);
+                    debug!("New UDP session: {} -> {} (via port {}, real client {})",
+                        client_addr, backend_addr, port, effective_client_ip);
 
                     // Spawn return-path relay task
                     let session_cancel = CancellationToken::new();
@@ -447,7 +672,7 @@ impl UdpListenerManager {
                         last_activity: std::sync::atomic::AtomicU64::new(session_table.elapsed_ms()),
                         created_at: std::time::Instant::now(),
                         route_id: route_id.map(|s| s.to_string()),
-                        source_ip: client_addr.ip(),
+                        source_ip: effective_client_ip,
                         client_addr,
                         return_task,
                         cancel: session_cancel,
@@ -458,8 +683,8 @@ impl UdpListenerManager {
                         continue;
                     }
 
-                    // Track in metrics
-                    conn_tracker.connection_opened(&client_addr.ip());
+                    // Track in metrics using the real client IP
+                    conn_tracker.connection_opened(&effective_client_ip);
                     metrics.connection_opened(route_id, Some(&ip_str));
                     metrics.udp_session_opened();
 

rust/crates/rustproxy-passthrough/src/udp_session.rs

@@ -201,6 +201,36 @@ impl UdpSessionTable {
         removed
     }
 
+    /// Drain all sessions on a given listening port, releasing socket references.
+    /// Used when upgrading a raw UDP listener to QUIC — the raw UDP socket's
+    /// Arc refcount must drop to zero so the port can be rebound.
+    pub fn drain_port(
+        &self,
+        port: u16,
+        metrics: &MetricsCollector,
+        conn_tracker: &ConnectionTracker,
+    ) -> usize {
+        let keys: Vec<SessionKey> = self.sessions.iter()
+            .filter(|entry| entry.key().1 == port)
+            .map(|entry| *entry.key())
+            .collect();
+
+        let mut removed = 0;
+        for key in keys {
+            if let Some(session) = self.remove(&key) {
+                session.cancel.cancel();
+                conn_tracker.connection_closed(&session.source_ip);
+                metrics.connection_closed(
+                    session.route_id.as_deref(),
+                    Some(&session.source_ip.to_string()),
+                );
+                metrics.udp_session_closed();
+                removed += 1;
+            }
+        }
+        removed
+    }
+
     /// Total number of active sessions.
     pub fn session_count(&self) -> usize {
         self.sessions.len()

rust/crates/rustproxy-routing/src/route_manager.rs

@@ -122,10 +122,16 @@ impl RouteManager {
                 // This prevents session-ticket resumption from misrouting when clients
                 // omit SNI (RFC 8446 recommends but doesn't mandate SNI on resumption).
                 // Wildcard-only routes (domains: ["*"]) still match since they accept all.
-                let patterns = domains.to_vec();
-                let is_wildcard_only = patterns.iter().all(|d| *d == "*");
-                if !is_wildcard_only {
-                    return false;
+                //
+                // Exception: QUIC (UDP transport) encrypts the TLS ClientHello, so SNI
+                // is unavailable at accept time. Domain verification happens per-request
+                // in H3ProxyService via the :authority header.
+                if ctx.transport != Some(TransportProtocol::Udp) {
+                    let patterns = domains.to_vec();
+                    let is_wildcard_only = patterns.iter().all(|d| *d == "*");
+                    if !is_wildcard_only {
+                        return false;
+                    }
                 }
             }
         }
@@ -997,4 +1003,52 @@ mod tests {
         let result = manager.find_route(&udp_ctx).unwrap();
         assert_eq!(result.route.name.as_deref(), Some("udp-route"));
     }
+
+    #[test]
+    fn test_quic_tls_no_sni_matches_domain_restricted_route() {
+        // QUIC accept-level matching: is_tls=true, domain=None, transport=Udp.
+        // Should match because QUIC encrypts the ClientHello — SNI is unavailable
+        // at accept time but verified per-request in H3ProxyService.
+        let mut route = make_route(443, Some("example.com"), 0);
+        route.route_match.transport = Some(TransportProtocol::Udp);
+        let routes = vec![route];
+        let manager = RouteManager::new(routes);
+
+        let ctx = MatchContext {
+            port: 443,
+            domain: None,
+            path: None,
+            client_ip: None,
+            tls_version: None,
+            headers: None,
+            is_tls: true,
+            protocol: Some("quic"),
+            transport: Some(TransportProtocol::Udp),
+        };
+
+        assert!(manager.find_route(&ctx).is_some(),
+            "QUIC (UDP) with is_tls=true and domain=None should match domain-restricted routes");
+    }
+
+    #[test]
+    fn test_tcp_tls_no_sni_still_rejects_domain_restricted_route() {
+        // TCP TLS without SNI must still be rejected (no QUIC exemption).
+        let routes = vec![make_route(443, Some("example.com"), 0)];
+        let manager = RouteManager::new(routes);
+
+        let ctx = MatchContext {
+            port: 443,
+            domain: None,
+            path: None,
+            client_ip: None,
+            tls_version: None,
+            headers: None,
+            is_tls: true,
+            protocol: None,
+            transport: None, // TCP (default)
+        };
+
+        assert!(manager.find_route(&ctx).is_none(),
+            "TCP TLS without SNI should NOT match domain-restricted routes");
+    }
 }

rust/crates/rustproxy/Cargo.toml

@@ -44,3 +44,9 @@ mimalloc = { workspace = true }
 
 [dev-dependencies]
 rcgen = { workspace = true }
+quinn = { workspace = true }
+h3 = { workspace = true }
+h3-quinn = { workspace = true }
+bytes = { workspace = true }
+rustls = { workspace = true }
+http = "1"

rust/crates/rustproxy/src/lib.rs

@@ -264,6 +264,8 @@ impl RustProxy {
             conn_config.socket_timeout_ms,
             conn_config.max_connection_lifetime_ms,
         );
+        // Clone proxy_ips before conn_config is moved into the TCP listener
+        let udp_proxy_ips = conn_config.proxy_ips.clone();
         listener.set_connection_config(conn_config);
 
         // Share the socket-handler relay path with the listener
@@ -339,6 +341,7 @@ impl RustProxy {
                 conn_tracker,
                 self.cancel_token.clone(),
             );
+            udp_mgr.set_proxy_ips(udp_proxy_ips.clone());
 
             // Construct H3ProxyService for HTTP/3 request handling
             let h3_svc = rustproxy_http::h3_service::H3ProxyService::new(
@@ -774,21 +777,22 @@ impl RustProxy {
                 if self.udp_listener_manager.is_none() {
                     if let Some(ref listener) = self.listener_manager {
                         let conn_tracker = listener.conn_tracker().clone();
-                        self.udp_listener_manager = Some(UdpListenerManager::new(
+                        let conn_config = Self::build_connection_config(&self.options);
+                        let mut udp_mgr = UdpListenerManager::new(
                             Arc::clone(&new_manager),
                             Arc::clone(&self.metrics),
                             conn_tracker,
                             self.cancel_token.clone(),
-                        ));
+                        );
+                        udp_mgr.set_proxy_ips(conn_config.proxy_ips);
+                        self.udp_listener_manager = Some(udp_mgr);
                     }
                 }
 
-                // Build TLS config for QUIC before taking mutable borrow on udp_mgr
-                let quic_tls = if new_udp_ports.iter().any(|p| !old_udp_ports.contains(p)) {
+                // Build TLS config for QUIC (needed for new ports and upgrading existing raw UDP)
+                let quic_tls = {
                     let tls_configs = self.current_tls_configs().await;
                     Self::build_quic_tls_config(&tls_configs)
-                } else {
-                    None
                 };
 
                 if let Some(ref mut udp_mgr) = self.udp_listener_manager {
@@ -806,6 +810,12 @@ impl RustProxy {
                             udp_mgr.remove_port(*port);
                         }
                     }
+
+                    // Upgrade existing raw UDP fallback listeners to QUIC if TLS is now available
+                    if let Some(ref quic_config) = quic_tls {
+                        udp_mgr.update_quic_tls(Arc::clone(quic_config));
+                        udp_mgr.upgrade_raw_to_quic(Arc::clone(quic_config)).await;
+                    }
                 }
             } else if self.udp_listener_manager.is_some() {
                 // All UDP routes removed — shut down UDP manager
@@ -862,12 +872,12 @@ impl RustProxy {
             .map_err(|e| anyhow::anyhow!("ACME provisioning failed: {}", e))?;
 
         // Hot-swap into TLS configs
-        if let Some(ref mut listener) = self.listener_manager {
-            let mut tls_configs = Self::extract_tls_configs(&self.options.routes);
-            tls_configs.insert(domain.clone(), TlsCertConfig {
-                cert_pem: bundle.cert_pem.clone(),
-                key_pem: bundle.key_pem.clone(),
-            });
+        let mut tls_configs = Self::extract_tls_configs(&self.options.routes);
+        tls_configs.insert(domain.clone(), TlsCertConfig {
+            cert_pem: bundle.cert_pem.clone(),
+            key_pem: bundle.key_pem.clone(),
+        });
+        {
             let cm = cm_arc.lock().await;
             for (d, b) in cm.store().iter() {
                 if !tls_configs.contains_key(d) {
@@ -877,9 +887,22 @@ impl RustProxy {
                     });
                 }
             }
+        }
+
+        let quic_tls = Self::build_quic_tls_config(&tls_configs);
+
+        if let Some(ref listener) = self.listener_manager {
             listener.set_tls_configs(tls_configs);
         }
 
+        // Update existing QUIC endpoints and upgrade raw UDP fallback listeners
+        if let Some(ref mut udp_mgr) = self.udp_listener_manager {
+            if let Some(ref quic_config) = quic_tls {
+                udp_mgr.update_quic_tls(Arc::clone(quic_config));
+                udp_mgr.upgrade_raw_to_quic(Arc::clone(quic_config)).await;
+            }
+        }
+
         info!("Certificate provisioned and loaded for route '{}'", route_name);
         Ok(())
     }
@@ -980,44 +1003,25 @@ impl RustProxy {
     fn build_quic_tls_config(
         tls_configs: &HashMap<String, TlsCertConfig>,
     ) -> Option<Arc<rustls::ServerConfig>> {
-        // Find the first available cert (prefer wildcard, then any)
-        let cert_config = tls_configs.get("*")
-            .or_else(|| tls_configs.values().next());
-
-        let cert_config = match cert_config {
-            Some(c) => c,
-            None => return None,
-        };
-
-        // Parse cert chain from PEM
-        let mut cert_reader = std::io::BufReader::new(cert_config.cert_pem.as_bytes());
-        let certs: Vec<rustls::pki_types::CertificateDer<'static>> =
-            rustls_pemfile::certs(&mut cert_reader)
-                .filter_map(|r| r.ok())
-                .collect();
-
-        if certs.is_empty() {
+        if tls_configs.is_empty() {
             return None;
         }
 
-        // Parse private key from PEM
-        let mut key_reader = std::io::BufReader::new(cert_config.key_pem.as_bytes());
-        let key = match rustls_pemfile::private_key(&mut key_reader) {
-            Ok(Some(key)) => key,
-            _ => return None,
-        };
-
-        let mut tls_config = match rustls::ServerConfig::builder()
-            .with_no_client_auth()
-            .with_single_cert(certs, key)
-        {
-            Ok(c) => c,
+        // Reuse CertResolver for SNI-based cert selection (same as TCP/TLS path).
+        // This ensures QUIC connections get the correct certificate for each domain
+        // instead of a single static cert.
+        let resolver = match rustproxy_passthrough::tls_handler::CertResolver::new(tls_configs) {
+            Ok(r) => r,
             Err(e) => {
-                warn!("Failed to build QUIC TLS config: {}", e);
+                warn!("Failed to build QUIC cert resolver: {}", e);
                 return None;
             }
         };
 
+        let mut tls_config = rustls::ServerConfig::builder()
+            .with_no_client_auth()
+            .with_cert_resolver(Arc::new(resolver));
+
         // QUIC requires h3 ALPN
         tls_config.alpn_protocols = vec![b"h3".to_vec()];
 
@@ -1104,17 +1108,18 @@ impl RustProxy {
         // Hot-swap TLS config on TCP and QUIC listeners
         let tls_configs = self.current_tls_configs().await;
 
+        // Build QUIC TLS config before TCP consumes the map
+        let quic_tls = Self::build_quic_tls_config(&tls_configs);
+
         if let Some(ref listener) = self.listener_manager {
-            // Build QUIC TLS config before TCP consumes the map
-            let quic_tls = Self::build_quic_tls_config(&tls_configs);
-
             listener.set_tls_configs(tls_configs);
+        }
 
-            // Also update QUIC endpoints with the new certs
-            if let Some(ref udp_mgr) = self.udp_listener_manager {
-                if let Some(quic_config) = quic_tls {
-                    udp_mgr.update_quic_tls(quic_config);
-                }
+        // Update existing QUIC endpoints and upgrade raw UDP fallback listeners
+        if let Some(ref mut udp_mgr) = self.udp_listener_manager {
+            if let Some(ref quic_config) = quic_tls {
+                udp_mgr.update_quic_tls(Arc::clone(quic_config));
+                udp_mgr.upgrade_raw_to_quic(Arc::clone(quic_config)).await;
             }
         }
 

rust/crates/rustproxy/tests/integration_h3_proxy.rs

@@ -0,0 +1,195 @@
+mod common;
+
+use common::*;
+use rustproxy::RustProxy;
+use rustproxy_config::{RustProxyOptions, TransportProtocol, RouteUdp, RouteQuic};
+use bytes::Buf;
+use std::sync::Arc;
+
+/// Build a route that listens on UDP with HTTP/3 enabled and TLS terminate.
+fn make_h3_route(
+    port: u16,
+    target_host: &str,
+    target_port: u16,
+    cert_pem: &str,
+    key_pem: &str,
+) -> rustproxy_config::RouteConfig {
+    let mut route = make_tls_terminate_route(port, "localhost", target_host, target_port, cert_pem, key_pem);
+    route.route_match.transport = Some(TransportProtocol::Udp);
+    // Keep domain="localhost" from make_tls_terminate_route — needed for TLS cert extraction
+    route.action.udp = Some(RouteUdp {
+        session_timeout: None,
+        max_sessions_per_ip: None,
+        max_datagram_size: None,
+        quic: Some(RouteQuic {
+            max_idle_timeout: Some(30000),
+            max_concurrent_bidi_streams: None,
+            max_concurrent_uni_streams: None,
+            enable_http3: Some(true),
+            alt_svc_port: None,
+            alt_svc_max_age: None,
+            initial_congestion_window: None,
+        }),
+    });
+    route
+}
+
+/// Build a quinn client endpoint with insecure TLS for testing.
+fn make_h3_client_endpoint() -> quinn::Endpoint {
+    let mut tls_config = rustls::ClientConfig::builder()
+        .dangerous()
+        .with_custom_certificate_verifier(Arc::new(InsecureVerifier))
+        .with_no_client_auth();
+    tls_config.alpn_protocols = vec![b"h3".to_vec()];
+
+    let quic_client_config = quinn::crypto::rustls::QuicClientConfig::try_from(tls_config)
+        .expect("Failed to build QUIC client config");
+    let client_config = quinn::ClientConfig::new(Arc::new(quic_client_config));
+
+    let mut endpoint = quinn::Endpoint::client("0.0.0.0:0".parse().unwrap())
+        .expect("Failed to create QUIC client endpoint");
+    endpoint.set_default_client_config(client_config);
+    endpoint
+}
+
+/// Test that HTTP/3 response streams properly finish (FIN is received by client).
+///
+/// This is the critical regression test for the FIN bug: the proxy must send
+/// a QUIC stream FIN after the response body so the client's `recv_data()`
+/// returns `None` instead of hanging forever.
+#[tokio::test]
+async fn test_h3_response_stream_finishes() {
+    let backend_port = next_port();
+    let proxy_port = next_port();
+    let body_text = "Hello from HTTP/3 backend! This body has a known length for testing.";
+
+    // 1. Start plain HTTP backend with known body + content-length
+    let _backend = start_http_server(backend_port, 200, body_text).await;
+
+    // 2. Generate self-signed cert and configure H3 route
+    let (cert_pem, key_pem) = generate_self_signed_cert("localhost");
+    let route = make_h3_route(proxy_port, "127.0.0.1", backend_port, &cert_pem, &key_pem);
+
+    let options = RustProxyOptions {
+        routes: vec![route],
+        ..Default::default()
+    };
+
+    // 3. Start proxy and wait for UDP bind
+    let mut proxy = RustProxy::new(options).unwrap();
+    proxy.start().await.unwrap();
+    tokio::time::sleep(std::time::Duration::from_millis(500)).await;
+
+    // 4. Connect QUIC/H3 client
+    let endpoint = make_h3_client_endpoint();
+    let addr: std::net::SocketAddr = format!("127.0.0.1:{}", proxy_port).parse().unwrap();
+    let connection = endpoint
+        .connect(addr, "localhost")
+        .expect("Failed to initiate QUIC connection")
+        .await
+        .expect("QUIC handshake failed");
+
+    let (mut driver, mut send_request) = h3::client::new(
+        h3_quinn::Connection::new(connection),
+    )
+    .await
+    .expect("H3 connection setup failed");
+
+    // Drive the H3 connection in background
+    tokio::spawn(async move {
+        let _ = driver.wait_idle().await;
+    });
+
+    // 5. Send GET request
+    let req = http::Request::builder()
+        .method("GET")
+        .uri("https://localhost/")
+        .header("host", "localhost")
+        .body(())
+        .unwrap();
+
+    let mut stream = send_request.send_request(req).await
+        .expect("Failed to send H3 request");
+    stream.finish().await
+        .expect("Failed to finish sending H3 request body");
+
+    // 6. Read response headers
+    let resp = stream.recv_response().await
+        .expect("Failed to receive H3 response");
+    assert_eq!(resp.status(), http::StatusCode::OK,
+        "Expected 200 OK, got {}", resp.status());
+
+    // 7. Read body and verify stream ends (FIN received)
+    //    This is the critical assertion: recv_data() must return None (stream ended)
+    //    within the timeout, NOT hang forever waiting for a FIN that never arrives.
+    let result = with_timeout(async {
+        let mut total = 0usize;
+        while let Some(chunk) = stream.recv_data().await.expect("H3 data receive error") {
+            total += chunk.remaining();
+        }
+        // recv_data() returned None => stream ended (FIN received)
+        total
+    }, 10)
+    .await;
+
+    let bytes_received = result.expect(
+        "TIMEOUT: H3 stream never ended (FIN not received by client). \
+         The proxy sent all response data but failed to send the QUIC stream FIN."
+    );
+    assert_eq!(
+        bytes_received,
+        body_text.len(),
+        "Expected {} bytes, got {}",
+        body_text.len(),
+        bytes_received
+    );
+
+    // 8. Cleanup
+    endpoint.close(quinn::VarInt::from_u32(0), b"test done");
+    proxy.stop().await.unwrap();
+}
+
+/// Insecure TLS verifier that accepts any certificate (for tests only).
+#[derive(Debug)]
+struct InsecureVerifier;
+
+impl rustls::client::danger::ServerCertVerifier for InsecureVerifier {
+    fn verify_server_cert(
+        &self,
+        _end_entity: &rustls::pki_types::CertificateDer<'_>,
+        _intermediates: &[rustls::pki_types::CertificateDer<'_>],
+        _server_name: &rustls::pki_types::ServerName<'_>,
+        _ocsp_response: &[u8],
+        _now: rustls::pki_types::UnixTime,
+    ) -> Result<rustls::client::danger::ServerCertVerified, rustls::Error> {
+        Ok(rustls::client::danger::ServerCertVerified::assertion())
+    }
+
+    fn verify_tls12_signature(
+        &self,
+        _message: &[u8],
+        _cert: &rustls::pki_types::CertificateDer<'_>,
+        _dss: &rustls::DigitallySignedStruct,
+    ) -> Result<rustls::client::danger::HandshakeSignatureValid, rustls::Error> {
+        Ok(rustls::client::danger::HandshakeSignatureValid::assertion())
+    }
+
+    fn verify_tls13_signature(
+        &self,
+        _message: &[u8],
+        _cert: &rustls::pki_types::CertificateDer<'_>,
+        _dss: &rustls::DigitallySignedStruct,
+    ) -> Result<rustls::client::danger::HandshakeSignatureValid, rustls::Error> {
+        Ok(rustls::client::danger::HandshakeSignatureValid::assertion())
+    }
+
+    fn supported_verify_schemes(&self) -> Vec<rustls::SignatureScheme> {
+        vec![
+            rustls::SignatureScheme::RSA_PKCS1_SHA256,
+            rustls::SignatureScheme::ECDSA_NISTP256_SHA256,
+            rustls::SignatureScheme::ECDSA_NISTP384_SHA384,
+            rustls::SignatureScheme::ED25519,
+            rustls::SignatureScheme::RSA_PSS_SHA256,
+        ]
+    }
+}

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartproxy',
-  version: '25.16.0',
+  version: '25.17.9',
   description: 'A powerful proxy package with unified route-based configuration for high traffic management. Features include SSL/TLS support, flexible routing patterns, WebSocket handling, advanced security options, and automatic ACME certificate management.'
 }