From 5468c3c410e408b21e4cfbd4034b72935b24cdcf Mon Sep 17 00:00:00 2001
From: Sebastian Mayr <sebmaster16@gmail.com>
Date: Mon, 2 Nov 2020 03:44:14 -0500
Subject: [PATCH] Drop content length headers from 101 responses (#1767)

Co-authored-by: Sebastian Mayr <smayr@atlassian.com>
---
 actix-http/CHANGES.md        |  4 ++++
 actix-http/src/h1/encoder.rs | 39 ++++++++++++++++++++++++++++++------
 actix-web-actors/src/ws.rs   |  9 ++++-----
 3 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/actix-http/CHANGES.md b/actix-http/CHANGES.md
index bb5a962f5..edb1409b2 100644
--- a/actix-http/CHANGES.md
+++ b/actix-http/CHANGES.md
@@ -1,6 +1,10 @@
 # Changes
 
 ## Unreleased - 2020-xx-xx
+### Fixed
+* Started dropping `transfer-encoding: chunked` and `Content-Length` for 1XX and 204 responses. [#1767]
+
+[#1767]: https://github.com/actix/actix-web/pull/1767
 
 
 ## 2.1.0 - 2020-10-30
diff --git a/actix-http/src/h1/encoder.rs b/actix-http/src/h1/encoder.rs
index e16b4c3dc..b7648eff1 100644
--- a/actix-http/src/h1/encoder.rs
+++ b/actix-http/src/h1/encoder.rs
@@ -64,14 +64,17 @@ pub(crate) trait MessageType: Sized {
         // Content length
         if let Some(status) = self.status() {
             match status {
-                StatusCode::NO_CONTENT
-                | StatusCode::CONTINUE
-                | StatusCode::PROCESSING => length = BodySize::None,
-                StatusCode::SWITCHING_PROTOCOLS => {
+                StatusCode::CONTINUE
+                | StatusCode::SWITCHING_PROTOCOLS
+                | StatusCode::PROCESSING
+                | StatusCode::NO_CONTENT => {
+                    // skip content-length and transfer-encoding headers
+                    // See https://tools.ietf.org/html/rfc7230#section-3.3.1
+                    // and https://tools.ietf.org/html/rfc7230#section-3.3.2
                     skip_len = true;
-                    length = BodySize::Stream;
+                    length = BodySize::None
                 }
-                _ => (),
+                _ => {}
             }
         }
         match length {
@@ -676,4 +679,28 @@ mod tests {
         assert!(data.contains("authorization: another authorization\r\n"));
         assert!(data.contains("date: date\r\n"));
     }
+
+    #[test]
+    fn test_no_content_length() {
+        let mut bytes = BytesMut::with_capacity(2048);
+
+        let mut res: Response<()> =
+            Response::new(StatusCode::SWITCHING_PROTOCOLS).into_body::<()>();
+        res.headers_mut()
+            .insert(DATE, HeaderValue::from_static(&""));
+        res.headers_mut()
+            .insert(CONTENT_LENGTH, HeaderValue::from_static(&"0"));
+
+        let _ = res.encode_headers(
+            &mut bytes,
+            Version::HTTP_11,
+            BodySize::Stream,
+            ConnectionType::Upgrade,
+            &ServiceConfig::default(),
+        );
+        let data =
+            String::from_utf8(Vec::from(bytes.split().freeze().as_ref())).unwrap();
+        assert!(!data.contains("content-length: 0\r\n"));
+        assert!(!data.contains("transfer-encoding: chunked\r\n"));
+    }
 }
diff --git a/actix-web-actors/src/ws.rs b/actix-web-actors/src/ws.rs
index 3f5972532..8fd03f6a1 100644
--- a/actix-web-actors/src/ws.rs
+++ b/actix-web-actors/src/ws.rs
@@ -164,7 +164,6 @@ pub fn handshake_with_protocols(
 
     let mut response = HttpResponse::build(StatusCode::SWITCHING_PROTOCOLS)
         .upgrade("websocket")
-        .header(header::TRANSFER_ENCODING, "chunked")
         .header(header::SEC_WEBSOCKET_ACCEPT, key.as_str())
         .take();
 
@@ -664,10 +663,10 @@ mod tests {
             )
             .to_http_request();
 
-        assert_eq!(
-            StatusCode::SWITCHING_PROTOCOLS,
-            handshake(&req).unwrap().finish().status()
-        );
+        let resp = handshake(&req).unwrap().finish();
+        assert_eq!(StatusCode::SWITCHING_PROTOCOLS, resp.status());
+        assert_eq!(None, resp.headers().get(&header::CONTENT_LENGTH));
+        assert_eq!(None, resp.headers().get(&header::TRANSFER_ENCODING));
 
         let req = TestRequest::default()
             .header(