files: file path filtering closure (#2274)

Co-authored-by: Rob Ede <robjtede@icloud.com>

actix-files/CHANGES.md

@@ -1,6 +1,9 @@
 # Changes
 
 ## Unreleased - 2021-xx-xx
+* Added `Files::path_filter()`. [#2274]
+
+[#2274]: https://github.com/actix/actix-web/pull/2274
 
 
 ## 0.6.0-beta.5 - 2021-06-17

actix-files/src/files.rs

@@ -1,9 +1,17 @@
-use std::{cell::RefCell, fmt, io, path::PathBuf, rc::Rc};
+use std::{
+    cell::RefCell,
+    fmt, io,
+    path::{Path, PathBuf},
+    rc::Rc,
+};
 
 use actix_service::{boxed, IntoServiceFactory, ServiceFactory, ServiceFactoryExt};
 use actix_utils::future::ok;
 use actix_web::{
-    dev::{AppService, HttpServiceFactory, ResourceDef, ServiceRequest, ServiceResponse},
+    dev::{
+        AppService, HttpServiceFactory, RequestHead, ResourceDef, ServiceRequest,
+        ServiceResponse,
+    },
     error::Error,
     guard::Guard,
     http::header::DispositionType,
@@ -13,7 +21,7 @@ use futures_core::future::LocalBoxFuture;
 
 use crate::{
     directory_listing, named, Directory, DirectoryRenderer, FilesService, HttpNewService,
-    MimeOverride,
+    MimeOverride, PathFilter,
 };
 
 /// Static files handling service.
@@ -36,6 +44,7 @@ pub struct Files {
     default: Rc<RefCell<Option<Rc<HttpNewService>>>>,
     renderer: Rc<DirectoryRenderer>,
     mime_override: Option<Rc<MimeOverride>>,
+    path_filter: Option<Rc<PathFilter>>,
     file_flags: named::Flags,
     use_guards: Option<Rc<dyn Guard>>,
     guards: Vec<Rc<dyn Guard>>,
@@ -60,6 +69,7 @@ impl Clone for Files {
             file_flags: self.file_flags,
             path: self.path.clone(),
             mime_override: self.mime_override.clone(),
+            path_filter: self.path_filter.clone(),
             use_guards: self.use_guards.clone(),
             guards: self.guards.clone(),
             hidden_files: self.hidden_files,
@@ -104,6 +114,7 @@ impl Files {
             default: Rc::new(RefCell::new(None)),
             renderer: Rc::new(directory_listing),
             mime_override: None,
+            path_filter: None,
             file_flags: named::Flags::default(),
             use_guards: None,
             guards: Vec::new(),
@@ -149,6 +160,38 @@ impl Files {
         self
     }
 
+    /// Sets path filtering closure.
+    ///
+    /// The path provided to the closure is relative to `serve_from` path.
+    /// You can safely join this path with the `serve_from` path to get the real path.
+    /// However, the real path may not exist since the filter is called before checking path existence.
+    ///
+    /// When a path doesn't pass the filter, [`Files::default_handler`] is called if set, otherwise,
+    /// `404 Not Found` is returned.
+    ///
+    /// # Examples
+    /// ```
+    /// use std::path::Path;
+    /// use actix_files::Files;
+    ///
+    /// // prevent searching subdirectories and following symlinks
+    /// let files_service = Files::new("/", "./static").path_filter(|path, _| {
+    ///     path.components().count() == 1
+    ///         && Path::new("./static")
+    ///             .join(path)
+    ///             .symlink_metadata()
+    ///             .map(|m| !m.file_type().is_symlink())
+    ///             .unwrap_or(false)
+    /// });
+    /// ```
+    pub fn path_filter<F>(mut self, f: F) -> Self
+    where
+        F: Fn(&Path, &RequestHead) -> bool + 'static,
+    {
+        self.path_filter = Some(Rc::new(f));
+        self
+    }
+
     /// Set index file
     ///
     /// Shows specific index file for directories instead of
@@ -318,6 +361,7 @@ impl ServiceFactory<ServiceRequest> for Files {
             default: None,
             renderer: self.renderer.clone(),
             mime_override: self.mime_override.clone(),
+            path_filter: self.path_filter.clone(),
             file_flags: self.file_flags,
             guards: self.use_guards.clone(),
             hidden_files: self.hidden_files,

actix-files/src/lib.rs

@@ -16,11 +16,12 @@
 
 use actix_service::boxed::{BoxService, BoxServiceFactory};
 use actix_web::{
-    dev::{ServiceRequest, ServiceResponse},
+    dev::{RequestHead, ServiceRequest, ServiceResponse},
     error::Error,
     http::header::DispositionType,
 };
 use mime_guess::from_ext;
+use std::path::Path;
 
 mod chunked;
 mod directory;
@@ -56,6 +57,8 @@ pub fn file_extension_to_mime(ext: &str) -> mime::Mime {
 
 type MimeOverride = dyn Fn(&mime::Name<'_>) -> DispositionType;
 
+type PathFilter = dyn Fn(&Path, &RequestHead) -> bool;
+
 #[cfg(test)]
 mod tests {
     use std::{
@@ -901,4 +904,40 @@ mod tests {
         let bytes = test::read_body(resp).await;
         assert!(format!("{:?}", bytes).contains("/tests/test.png"));
     }
+
+    #[actix_rt::test]
+    async fn test_path_filter() {
+        // prevent searching subdirectories
+        let st = Files::new("/", ".")
+            .path_filter(|path, _| path.components().count() == 1)
+            .new_service(())
+            .await
+            .unwrap();
+
+        let req = TestRequest::with_uri("/Cargo.toml").to_srv_request();
+        let resp = test::call_service(&st, req).await;
+        assert_eq!(resp.status(), StatusCode::OK);
+
+        let req = TestRequest::with_uri("/src/lib.rs").to_srv_request();
+        let resp = test::call_service(&st, req).await;
+        assert_eq!(resp.status(), StatusCode::NOT_FOUND);
+    }
+
+    #[actix_rt::test]
+    async fn test_default_handler_filter() {
+        let st = Files::new("/", ".")
+            .default_handler(|req: ServiceRequest| {
+                ok(req.into_response(HttpResponse::Ok().body("default content")))
+            })
+            .path_filter(|path, _| path.extension() == Some("png".as_ref()))
+            .new_service(())
+            .await
+            .unwrap();
+        let req = TestRequest::with_uri("/Cargo.toml").to_srv_request();
+        let resp = test::call_service(&st, req).await;
+
+        assert_eq!(resp.status(), StatusCode::OK);
+        let bytes = test::read_body(resp).await;
+        assert_eq!(bytes, web::Bytes::from_static(b"default content"));
+    }
 }

actix-files/src/service.rs

@@ -13,7 +13,7 @@ use futures_core::future::LocalBoxFuture;
 
 use crate::{
     named, Directory, DirectoryRenderer, FilesError, HttpService, MimeOverride, NamedFile,
-    PathBufWrap,
+    PathBufWrap, PathFilter,
 };
 
 /// Assembled file serving service.
@@ -25,6 +25,7 @@ pub struct FilesService {
     pub(crate) default: Option<HttpService>,
     pub(crate) renderer: Rc<DirectoryRenderer>,
     pub(crate) mime_override: Option<Rc<MimeOverride>>,
+    pub(crate) path_filter: Option<Rc<PathFilter>>,
     pub(crate) file_flags: named::Flags,
     pub(crate) guards: Option<Rc<dyn Guard>>,
     pub(crate) hidden_files: bool,
@@ -82,6 +83,18 @@ impl Service<ServiceRequest> for FilesService {
                 Err(e) => return Box::pin(ok(req.error_response(e))),
             };
 
+        if let Some(filter) = &self.path_filter {
+            if !filter(real_path.as_ref(), req.head()) {
+                if let Some(ref default) = self.default {
+                    return Box::pin(default.call(req));
+                } else {
+                    return Box::pin(ok(
+                        req.into_response(actix_web::HttpResponse::NotFound().finish())
+                    ));
+                }
+            }
+        }
+
         // full file path
         let path = self.directory.join(&real_path);
         if let Err(err) = path.canonicalize() {