Additionally set expires header when caching responses

Browsers are rather smart, but also dumb. This uses the `Expires` header
alongside `cache-control` to better prompt the browser to actually
cache.

Unfortunately, firefox still tries to "race" its own cache, in an
attempt to respond to requests faster, so still ends up making a bunch
of requests which could have been cached. Doesn't appear there's any way
around this.

Cargo.lock

@@ -3295,6 +3295,7 @@ dependencies = [
  "governor",
  "handlebars",
  "html5ever",
+ "httpdate",
  "idna 0.2.3",
  "job_scheduler",
  "jsonwebtoken",

Cargo.toml

@@ -80,6 +80,7 @@ uuid = { version = "0.8.2", features = ["v4"] }
 chrono = { version = "0.4.19", features = ["serde"] }
 chrono-tz = "0.6.1"
 time = "0.2.27"
+httpdate = "1.0"
 
 # Job scheduler
 job_scheduler = "1.2.1"

src/api/icons.rs

@@ -103,14 +103,19 @@ fn icon_internal(domain: String) -> Cached<Content<Vec<u8>>> {
         return Cached::ttl(
             Content(ContentType::new("image", "png"), FALLBACK_ICON.to_vec()),
             CONFIG.icon_cache_negttl(),
+            true,
         );
     }
 
     match get_icon(&domain) {
         Some((icon, icon_type)) => {
-            Cached::ttl(Content(ContentType::new("image", icon_type), icon), CONFIG.icon_cache_ttl())
+            Cached::ttl(Content(ContentType::new("image", icon_type), icon), CONFIG.icon_cache_ttl(), true)
         }
-        _ => Cached::ttl(Content(ContentType::new("image", "png"), FALLBACK_ICON.to_vec()), CONFIG.icon_cache_negttl()),
+        _ => Cached::ttl(
+            Content(ContentType::new("image", "png"), FALLBACK_ICON.to_vec()),
+            CONFIG.icon_cache_negttl(),
+            true,
+        ),
     }
 }
 

src/api/web.rs

@@ -22,14 +22,15 @@ pub fn routes() -> Vec<Route> {
 
 #[get("/")]
 fn web_index() -> Cached<Option<NamedFile>> {
-    Cached::short(NamedFile::open(Path::new(&CONFIG.web_vault_folder()).join("index.html")).ok())
+    Cached::short(NamedFile::open(Path::new(&CONFIG.web_vault_folder()).join("index.html")).ok(), false)
 }
 
 #[get("/app-id.json")]
 fn app_id() -> Cached<Content<Json<Value>>> {
     let content_type = ContentType::new("application", "fido.trusted-apps+json");
 
-    Cached::long(Content(
+    Cached::long(
+        Content(
             content_type,
             Json(json!({
             "trustedFacets": [
@@ -51,12 +52,14 @@ fn app_id() -> Cached<Content<Json<Value>>> {
                     "android:apk-key-hash:dUGFzUzf3lmHSLBDBIv+WaFyZMI" ]
                 }]
             })),
-    ))
+        ),
+        true,
+    )
 }
 
 #[get("/<p..>", rank = 10)] // Only match this if the other routes don't match
 fn web_files(p: PathBuf) -> Cached<Option<NamedFile>> {
-    Cached::long(NamedFile::open(Path::new(&CONFIG.web_vault_folder()).join(p)).ok())
+    Cached::long(NamedFile::open(Path::new(&CONFIG.web_vault_folder()).join(p)).ok(), true)
 }
 
 #[get("/attachments/<uuid>/<file_id>")]

src/util.rs

@@ -11,6 +11,10 @@ use rocket::{
     Data, Request, Response, Rocket,
 };
 
+use httpdate::HttpDate;
+use std::thread::sleep;
+use std::time::{Duration, SystemTime};
+
 use crate::CONFIG;
 
 pub struct AppHeaders();
@@ -99,29 +103,52 @@ impl Fairing for Cors {
     }
 }
 
-pub struct Cached<R>(R, String);
+pub struct Cached<R> {
+    response: R,
+    is_immutable: bool,
+    ttl: u64,
+}
 
 impl<R> Cached<R> {
-    pub fn long(r: R) -> Cached<R> {
-        // 7 days
-        Self::ttl(r, 604800)
+    pub fn long(response: R, is_immutable: bool) -> Cached<R> {
+        Self {
+            response,
+            is_immutable,
+            ttl: 604800, // 7 days
+        }
     }
 
-    pub fn short(r: R) -> Cached<R> {
-        // 10 minutes
-        Self(r, String::from("public, max-age=600"))
+    pub fn short(response: R, is_immutable: bool) -> Cached<R> {
+        Self {
+            response,
+            is_immutable,
+            ttl: 600, // 10 minutes
+        }
     }
 
-    pub fn ttl(r: R, ttl: u64) -> Cached<R> {
-        Self(r, format!("public, immutable, max-age={}", ttl))
+    pub fn ttl(response: R, ttl: u64, is_immutable: bool) -> Cached<R> {
+        Self {
+            response,
+            is_immutable,
+            ttl: ttl,
+        }
     }
 }
 
 impl<'r, R: Responder<'r>> Responder<'r> for Cached<R> {
     fn respond_to(self, req: &Request) -> response::Result<'r> {
-        match self.0.respond_to(req) {
+        let cache_control_header = if self.is_immutable {
+            format!("public, immutable, max-age={}", self.ttl)
+        } else {
+            format!("public, max-age={}", self.ttl)
+        };
+
+        let time_now = SystemTime::now();
+
+        match self.response.respond_to(req) {
             Ok(mut res) => {
-                res.set_raw_header("Cache-Control", self.1);
+                res.set_raw_header("Cache-Control", cache_control_header);
+                res.set_raw_header("Expires", HttpDate::from(time_now + Duration::from_secs(self.ttl)).to_string());
                 Ok(res)
             }
             e @ Err(_) => e,
@@ -551,8 +578,6 @@ where
     }
 }
 
-use std::{thread::sleep, time::Duration};
-
 pub fn retry_db<F, T, E>(func: F, max_tries: u32) -> Result<T, E>
 where
     F: Fn() -> Result<T, E>,