fix(multipart): optional content-disposition for non-form-data requests (#3416)

actix-multipart/src/error.rs

@@ -11,77 +11,95 @@ use derive_more::{Display, Error, From};
 #[derive(Debug, Display, From, Error)]
 #[non_exhaustive]
 pub enum MultipartError {
-    /// Content-Disposition header is not found or is not equal to "form-data".
+    /// Could not find Content-Type header.
+    #[display(fmt = "Could not find Content-Type header")]
+    ContentTypeMissing,
+
+    /// Could not parse Content-Type header.
+    #[display(fmt = "Could not parse Content-Type header")]
+    ContentTypeParse,
+
+    /// Parsed Content-Type did not have "multipart" top-level media type.
     ///
-    /// According to [RFC 7578 §4.2](https://datatracker.ietf.org/doc/html/rfc7578#section-4.2) a
-    /// Content-Disposition header must always be present and equal to "form-data".
-    #[display(fmt = "No Content-Disposition `form-data` header")]
-    NoContentDisposition,
+    /// Also raised when extracting a [`MultipartForm`] from a request that does not have the
+    /// "multipart/form-data" media type.
+    ///
+    /// [`MultipartForm`]: struct@crate::form::MultipartForm
+    #[display(fmt = "Parsed Content-Type did not have "multipart" top-level media type")]
+    ContentTypeIncompatible,
 
-    /// Content-Type header is not found
-    #[display(fmt = "No Content-Type header found")]
-    NoContentType,
-
-    /// Can not parse Content-Type header
-    #[display(fmt = "Can not parse Content-Type header")]
-    ParseContentType,
-
-    /// Multipart boundary is not found
+    /// Multipart boundary is not found.
     #[display(fmt = "Multipart boundary is not found")]
-    Boundary,
+    BoundaryMissing,
 
-    /// Nested multipart is not supported
+    /// Content-Disposition header was not found or not of disposition type "form-data" when parsing
+    /// a "form-data" field.
+    ///
+    /// As per [RFC 7578 §4.2], a "multipart/form-data" field's Content-Disposition header must
+    /// always be present and have a disposition type of "form-data".
+    ///
+    /// [RFC 7578 §4.2]: https://datatracker.ietf.org/doc/html/rfc7578#section-4.2
+    #[display(fmt = "Content-Disposition header was not found when parsing a \"form-data\" field")]
+    ContentDispositionMissing,
+
+    /// Content-Disposition name parameter was not found when parsing a "form-data" field.
+    ///
+    /// As per [RFC 7578 §4.2], a "multipart/form-data" field's Content-Disposition header must
+    /// always include a "name" parameter.
+    ///
+    /// [RFC 7578 §4.2]: https://datatracker.ietf.org/doc/html/rfc7578#section-4.2
+    #[display(fmt = "Content-Disposition header was not found when parsing a \"form-data\" field")]
+    ContentDispositionNameMissing,
+
+    /// Nested multipart is not supported.
     #[display(fmt = "Nested multipart is not supported")]
     Nested,
 
-    /// Multipart stream is incomplete
+    /// Multipart stream is incomplete.
     #[display(fmt = "Multipart stream is incomplete")]
     Incomplete,
 
-    /// Error during field parsing
-    #[display(fmt = "{}", _0)]
+    /// Field parsing failed.
+    #[display(fmt = "Error during field parsing")]
     Parse(ParseError),
 
-    /// Payload error
-    #[display(fmt = "{}", _0)]
+    /// HTTP payload error.
+    #[display(fmt = "Payload error")]
     Payload(PayloadError),
 
-    /// Not consumed
-    #[display(fmt = "Multipart stream is not consumed")]
+    /// Stream is not consumed.
+    #[display(fmt = "Stream is not consumed")]
     NotConsumed,
 
-    /// An error from a field handler in a form
-    #[display(
-        fmt = "An error occurred processing field `{}`: {}",
-        field_name,
-        source
-    )]
+    /// Form field handler raised error.
+    #[display(fmt = "An error occurred processing field: {name}")]
     Field {
-        field_name: String,
+        name: String,
         source: actix_web::Error,
     },
 
-    /// Duplicate field
-    #[display(fmt = "Duplicate field found for: `{}`", _0)]
+    /// Duplicate field found (for structure that opted-in to denying duplicate fields).
+    #[display(fmt = "Duplicate field found: {_0}")]
     #[from(ignore)]
     DuplicateField(#[error(not(source))] String),
 
-    /// Missing field
-    #[display(fmt = "Field with name `{}` is required", _0)]
+    /// Required field is missing.
+    #[display(fmt = "Required field is missing: {_0}")]
     #[from(ignore)]
     MissingField(#[error(not(source))] String),
 
-    /// Unknown field
-    #[display(fmt = "Unsupported field `{}`", _0)]
+    /// Unknown field (for structure that opted-in to denying unknown fields).
+    #[display(fmt = "Unknown field: {_0}")]
     #[from(ignore)]
-    UnsupportedField(#[error(not(source))] String),
+    UnknownField(#[error(not(source))] String),
 }
 
-/// Return `BadRequest` for `MultipartError`
+/// Return `BadRequest` for `MultipartError`.
 impl ResponseError for MultipartError {
     fn status_code(&self) -> StatusCode {
         match &self {
             MultipartError::Field { source, .. } => source.as_response_error().status_code(),
+            MultipartError::ContentTypeIncompatible => StatusCode::UNSUPPORTED_MEDIA_TYPE,
             _ => StatusCode::BAD_REQUEST,
         }
     }
@@ -93,7 +111,7 @@ mod tests {
 
     #[test]
     fn test_multipart_error() {
-        let resp = MultipartError::Boundary.error_response();
+        let resp = MultipartError::BoundaryMissing.error_response();
         assert_eq!(resp.status(), StatusCode::BAD_REQUEST);
     }
 }