feat: deny non hx-requests on fragment

src/router/link.rs

@@ -4,9 +4,14 @@ use axum::{
     routing::get,
     Router,
 };
+use axum_extra::TypedHeader;
 use reqwest::StatusCode;
 
-use crate::{templates::DownloadLinkTemplate, AppState, AsyncRemoveRecord};
+use crate::{
+    templates::{self, DownloadLinkTemplate},
+    util::headers::HxRequest,
+    AppState, AsyncRemoveRecord,
+};
 
 pub fn get_link_router() -> Router<AppState> {
     // Link pages
@@ -62,12 +67,22 @@ async fn link_delete(
 
 async fn remaining(
     State(state): State<AppState>,
+    hx_request: Option<TypedHeader<HxRequest>>,
     axum::extract::Path(id): axum::extract::Path<String>,
-) -> impl IntoResponse {
-    let records = state.records.lock().await;
-    if let Some(record) = records.get(&id) {
-        Html(crate::templates::get_downloads_remaining_text(record))
-    } else {
-        Html("?".to_string())
+) -> Result<impl IntoResponse, (StatusCode, String)> {
+    if hx_request.is_none() {
+        return Err((
+            StatusCode::BAD_REQUEST,
+            "Attempt to fetch html fragment from non-htmx request".to_string(),
+        ));
     }
+
+    let records = state.records.lock().await;
+
+    Ok(Html(
+        records
+            .get(&id)
+            .map(templates::get_downloads_remaining_text)
+            .unwrap_or_else(|| "?".to_string()),
+    ))
 }

src/util/headers.rs

@@ -31,3 +31,38 @@ impl Header for ForwardedFor {
         values.extend(std::iter::once(HeaderValue::from_str(&self.0).unwrap()));
     }
 }
+
+#[derive(Debug)]
+pub struct HxRequest;
+
+pub static HXR_TEXT: &str = "hx-request";
+
+pub static HXR_NAME: HeaderName = HeaderName::from_static(HXR_TEXT);
+
+impl Header for HxRequest {
+    fn name() -> &'static HeaderName {
+        &FF_NAME
+    }
+
+    fn decode<'i, I>(values: &mut I) -> Result<Self, headers::Error>
+    where
+        Self: Sized,
+        I: Iterator<Item = &'i headers::HeaderValue>,
+    {
+        let value = values
+            .next()
+            .ok_or_else(headers::Error::invalid)?
+            .to_str()
+            .map_err(|_| headers::Error::invalid())?
+            .to_owned();
+
+        match &value[..] {
+            "true" => Ok(HxRequest),
+            _ => Err(headers::Error::invalid()),
+        }
+    }
+
+    fn encode<E: Extend<headers::HeaderValue>>(&self, values: &mut E) {
+        values.extend(std::iter::once(HeaderValue::from_static("true")));
+    }
+}