v25.16.2

changelog.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## 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
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@push.rocks/smartproxy",
-  "version": "25.16.1",
+  "version": "25.16.2",
   "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",

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")
@@ -703,9 +707,11 @@ impl HttpProxyService {
             ProtocolDecision::AlpnProbe => (false, true),
         };
 
-        // Track whether H3 connect failed — suppresses Alt-Svc re-caching to prevent
-        // the loop: H3 cached → QUIC timeout → H2/H1 fallback → Alt-Svc re-caches H3 → repeat
-        let mut h3_connect_failed = false;
+        // 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 {
@@ -742,7 +748,9 @@ impl HttpProxyService {
                 Err(e) => {
                     warn!(backend = %upstream_key, error = %e,
                         "H3 backend connect failed, falling back to H2/H1");
-                    h3_connect_failed = true;
+                    // 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 {
@@ -948,22 +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 ---
-        // Suppress Alt-Svc caching when we just failed an H3 attempt to prevent the loop:
-        // H3 cached → QUIC timeout → fallback → Alt-Svc re-caches H3 → repeat.
-        // The ALPN probe already cached H1 or H2; it will expire after 5min TTL,
-        // at which point we'll re-probe and see Alt-Svc again, retrying QUIC then.
-        if is_auto_detect_mode && !h3_connect_failed {
-            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
     }
 
@@ -1762,6 +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);
 

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartproxy',
-  version: '25.16.1',
+  version: '25.16.2',
   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.'
 }