feat: add option to ignore content-length with multipart body (#919)

The `max_length` field is changed to accept an `impl Into<Option<u64>>`, so people can pass `None` to disable the limit.

src/filters/multipart.rs

@@ -27,7 +27,7 @@ const DEFAULT_FORM_DATA_MAX_LENGTH: u64 = 1024 * 1024 * 2;
 /// Create with the `warp::multipart::form()` function.
 #[derive(Debug, Clone)]
 pub struct FormOptions {
-    max_length: u64,
+    max_length: Option<u64>,
 }
 
 /// A `Stream` of multipart/form-data `Part`s.
@@ -50,7 +50,7 @@ pub struct Part {
 /// in turn is a `Stream` of bytes.
 pub fn form() -> FormOptions {
     FormOptions {
-        max_length: DEFAULT_FORM_DATA_MAX_LENGTH,
+        max_length: Some(DEFAULT_FORM_DATA_MAX_LENGTH),
     }
 }
 
@@ -59,9 +59,10 @@ pub fn form() -> FormOptions {
 impl FormOptions {
     /// Set the maximum byte length allowed for this body.
     ///
+    /// `max_length(None)` means that maximum byte length is not checked.
     /// Defaults to 2MB.
-    pub fn max_length(mut self, max: u64) -> Self {
-        self.max_length = max;
+    pub fn max_length(mut self, max: impl Into<Option<u64>>) -> Self {
+        self.max_length = max.into();
         self
     }
 }
@@ -83,8 +84,7 @@ impl FilterBase for FormOptions {
             future::ready(mime)
         });
 
-        let filt = super::body::content_length_limit(self.max_length)
-            .and(boundary)
+        let filt = boundary
             .and(super::body::body())
             .map(|boundary: String, body| {
                 let body = BodyIoError(body);
@@ -93,9 +93,15 @@ impl FilterBase for FormOptions {
                 }
             });
 
-        let fut = filt.filter(Internal);
-
-        Box::pin(fut)
+        if let Some(max_length) = self.max_length {
+            Box::pin(
+                super::body::content_length_limit(max_length)
+                    .and(filt)
+                    .filter(Internal),
+            )
+        } else {
+            Box::pin(filt.filter(Internal))
+        }
     }
 }
 

tests/multipart.rs

@@ -52,3 +52,51 @@ async fn form_fields() {
     assert_eq!(&vec[0].0, "foo");
     assert_eq!(&vec[0].1, b"bar");
 }
+
+#[tokio::test]
+async fn max_length_is_enforced() {
+    let _ = pretty_env_logger::try_init();
+
+    let route = multipart::form()
+        .and_then(|_: multipart::FormData| async { Ok::<(), warp::Rejection>(()) });
+
+    let boundary = "--abcdef1234--";
+
+    let req = warp::test::request()
+        .method("POST")
+        // Note no content-length header
+        .header("transfer-encoding", "chunked")
+        .header(
+            "content-type",
+            format!("multipart/form-data; boundary={}", boundary),
+        );
+
+    // Intentionally don't add body, as it automatically also adds
+    // content-length header
+    let resp = req.filter(&route).await;
+    assert!(resp.is_err());
+}
+
+#[tokio::test]
+async fn max_length_can_be_disabled() {
+    let _ = pretty_env_logger::try_init();
+
+    let route = multipart::form()
+        .max_length(None)
+        .and_then(|_: multipart::FormData| async { Ok::<(), warp::Rejection>(()) });
+
+    let boundary = "--abcdef1234--";
+
+    let req = warp::test::request()
+        .method("POST")
+        .header("transfer-encoding", "chunked")
+        .header(
+            "content-type",
+            format!("multipart/form-data; boundary={}", boundary),
+        );
+
+    // Intentionally don't add body, as it automatically also adds
+    // content-length header
+    let resp = req.filter(&route).await;
+    assert!(resp.is_ok());
+}