Rewrite url paths

HTML files should only be accessible without their file ending. Index
files should only be accessible via a path that ends in `/`, not
directly via name,

showbits-thermal-printer/src/server/static.rs

@@ -8,21 +8,57 @@ use rust_embed::RustEmbed;
 #[folder = "static"]
 struct StaticFiles;
 
-struct StaticFile(pub String);
+struct StaticFile(String);
+
+fn not_found() -> Response {
+    (StatusCode::NOT_FOUND, "404 Not Found").into_response()
+}
+
+fn look_up_path(path: &str) -> Option<Response> {
+    let path = path.trim_start_matches('/');
+    let file = StaticFiles::get(path)?;
+    let mime = mime_guess::from_path(path).first_or_octet_stream();
+    let response = ([(header::CONTENT_TYPE, mime.as_ref())], file.data).into_response();
+    Some(response)
+}
 
 impl IntoResponse for StaticFile {
     fn into_response(self) -> Response {
-        match StaticFiles::get(&self.0) {
-            None => (StatusCode::NOT_FOUND, "404 Not Found").into_response(),
-            Some(file) => {
-                let mime = mime_guess::from_path(self.0).first_or_octet_stream();
-                ([(header::CONTENT_TYPE, mime.as_ref())], file.data).into_response()
-            }
+        let mut path = self.0;
+        if path.is_empty() {
+            path.push('/')
+        };
+
+        if path.ends_with(".html") {
+            // A file `/foo/bar.html` should not be accessible directly, only
+            // indirectly at `/foo/bar`.
+            return not_found();
         }
+
+        if path.ends_with("/index") {
+            // A file `/foo/index.html` should not be accessible directly, only
+            // indirectly at `/foo/`.
+            return not_found();
+        }
+
+        if path.ends_with('/') {
+            path.push_str("index");
+        }
+
+        if let Some(response) = look_up_path(&path) {
+            return response;
+        }
+
+        path.push_str(".html");
+
+        if let Some(response) = look_up_path(&path) {
+            return response;
+        }
+
+        not_found()
     }
 }
 
 pub async fn get_static_file(uri: Uri) -> impl IntoResponse {
-    let path = uri.path().trim_start_matches('/').to_string();
-    StaticFile(path)
+    StaticFile(uri.path().to_string())
 }