v0.28.0

src/cache/model/entry.rs

@@ -126,6 +126,15 @@ impl Settings {
             (1..=64).contains(&self.proactive_refresh_max_inflight),
             "cache.proactive_refresh_max_inflight must be 1..64"
         );
+        if let Some(value) = &self.via_header {
+            ensure!(
+                !value.is_empty()
+                    && value.len() <= 256
+                    && value.bytes().all(|byte| byte >= 0x20 && byte != 0x7f)
+                    && value.parse::<HeaderValue>().is_ok(),
+                "cache.via_header must be a valid 1..256 byte HTTP header value"
+            );
+        }
         Ok(())
     }
     pub fn active_for(&self, route: Option<bool>) -> bool {
@@ -173,6 +182,12 @@ impl Settings {
         if !self.enabled {
             return;
         }
+        if let Some(value) = &self.via_header {
+            headers.append(
+                http::header::VIA,
+                value.parse::<HeaderValue>().expect("validated cache Via header"),
+            );
+        }
         if self.expose_status {
             headers.insert("x-cache", HeaderValue::from_static(outcome));
         }

src/cache/model/settings.rs

@@ -173,6 +173,9 @@ pub struct Settings {
     pub expose_hits: bool,
     pub expose_cache_status: bool,
     pub expose_resident_age: bool,
+    /// Optional response Via field value added by RustProxy cache handling.
+    /// `None` disables the header; the default is `Via: RustProxy`.
+    pub via_header: Option<String>,
 }
 impl Default for Settings {
     fn default() -> Self {
@@ -240,6 +243,7 @@ impl Default for Settings {
             expose_hits: false,
             expose_cache_status: false,
             expose_resident_age: false,
+            via_header: Some("RustProxy".into()),
         }
     }
 }

src/cache/tests/dashboard_tests.rs

@@ -126,6 +126,25 @@ mod dashboard_tests {
             "RustProxy; fwd=bypass; detail=\"request_cookie\"; transformed"
         );
     }
+    #[test]
+    fn via_header_is_configurable_and_preserves_upstream_chain() {
+        let settings = Settings::default();
+        let mut headers = HeaderMap::new();
+        headers.append("via", HeaderValue::from_static("1.1 upstream"));
+        settings.annotate(&mut headers, "HIT", 1, 20);
+        let values: Vec<_> = headers
+            .get_all("via")
+            .iter()
+            .map(|value| value.to_str().unwrap())
+            .collect();
+        assert_eq!(values, vec!["1.1 upstream", "RustProxy"]);
+
+        let disabled = Settings { via_header: None, ..Settings::default() };
+        let mut headers = HeaderMap::new();
+        disabled.annotate(&mut headers, "MISS", 0, 0);
+        assert!(!headers.contains_key("via"));
+    }
+
     #[test]
     fn disabled_cache_strips_diagnostics_without_exposing_bypass_headers() {
         let settings = Settings {