etag headers

0x7d8 · 0x7d8 · commit 0fc5dc43136d · 2025-03-15T12:36:02.000+01:00
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "api"
-version = "2.1.1"
+version = "2.1.2"
 edition = "2024"
 
 [dependencies]
@@ -23,3 +23,4 @@ reqwest = { version = "0.12.12", default-features = false, features = ["json"] }
 nestify = "0.3.3"
 sha2 = "0.10.8"
 sentry-tower = { version = "0.36.0", features = ["http"] }
+sha1 = "0.10.6"
diff --git a/src/main.rs b/src/main.rs
@@ -9,12 +9,16 @@ mod telemetry;
 
 use axum::{
     body::Body,
-    http::{HeaderMap, Request, Response, StatusCode},
+    extract::Request,
+    http::{HeaderMap, StatusCode},
+    middleware::Next,
+    response::Response,
     routing::get,
 };
 use colored::Colorize;
 use sentry_tower::SentryHttpLayer;
 use serde_json::json;
+use sha1::Digest;
 use std::{sync::Arc, time::Instant};
 use tokio::sync::RwLock;
 use tower_http::{catch_panic::CatchPanicLayer, cors::CorsLayer, trace::TraceLayer};
@@ -65,6 +69,36 @@ fn handle_request(req: &Request<Body>, _span: &tracing::Span) {
     );
 }
 
+async fn handle_etag(req: Request, next: Next) -> Result<Response, StatusCode> {
+    let if_none_match = req.headers().get("If-None-Match").cloned();
+
+    let response = next.run(req).await;
+    let mut hash = sha1::Sha1::new();
+
+    let (mut parts, body) = response.into_parts();
+    let body_bytes = axum::body::to_bytes(body, usize::MAX).await.unwrap();
+
+    hash.update(body_bytes.as_ref());
+    let hash = format!("{:x}", hash.finalize());
+
+    parts.headers.insert("ETag", hash.parse().unwrap());
+
+    if if_none_match == Some(hash.parse().unwrap()) {
+        let mut cached_response = Response::builder()
+            .status(StatusCode::NOT_MODIFIED)
+            .body(Body::empty())
+            .unwrap();
+
+        for (key, value) in parts.headers.iter() {
+            cached_response.headers_mut().insert(key, value.clone());
+        }
+
+        return Ok(cached_response);
+    }
+
+    Ok(Response::from_parts(parts, Body::from(body_bytes)))
+}
+
 #[tokio::main]
 async fn main() {
     let env = env::Env::parse();
@@ -142,6 +176,7 @@ async fn main() {
                 })),
             )
         })
+        .route_layer(axum::middleware::from_fn(handle_etag))
         .layer(CatchPanicLayer::custom(handle_panic))
         .layer(CorsLayer::very_permissive())
         .layer(TraceLayer::new_for_http().on_request(handle_request))
