From c76056bc7e8afddf3fdabb961a3e549a004c5b17 Mon Sep 17 00:00:00 2001
From: Yinuo Deng <i@dyn.im>
Date: Fri, 14 Apr 2023 21:43:31 +0800
Subject: [PATCH] Set mime type for stream response if it is not set by the
 user

---
 actix-web/src/response/builder.rs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/actix-web/src/response/builder.rs b/actix-web/src/response/builder.rs
index 120d4c358..c454ee6da 100644
--- a/actix-web/src/response/builder.rs
+++ b/actix-web/src/response/builder.rs
@@ -323,6 +323,17 @@ impl HttpResponseBuilder {
         S: Stream<Item = Result<Bytes, E>> + 'static,
         E: Into<BoxError> + 'static,
     {
+        // Set mime type to application/octet-stream if it is not set
+        let contains_mime = if let Some(parts) = self.inner() {
+            parts.headers.contains_key(header::CONTENT_TYPE)
+        } else {
+            true
+        };
+
+        if !contains_mime {
+            self.insert_header((header::CONTENT_TYPE, mime::APPLICATION_OCTET_STREAM));
+        }
+
         self.body(BodyStream::new(stream))
     }