From 12ee9e0f21c322e9d85b5c2413f6d6237b739216 Mon Sep 17 00:00:00 2001
From: akasakariko <148060537+akasakariko@users.noreply.github.com>
Date: Tue, 27 Oct 2026 21:30:59 +0900
Subject: [PATCH] fix(http1): avoid adding close to switching protocols
 responses

Do not append Connection: close to an HTTP/1.1 101 response when HTTP keep-alive is disabled
The connection is handed off to the upgraded protocol rather than closed

Extend the existing upgrade test to cover a request with Connection: close, Upgrade
Verify the response headers while retaining the buffered-byte and upgraded-I/O checks

Fixes #4244
---
 src/proto/h1/conn.rs |  4 +++-
 src/proto/h1/mod.rs  |  4 ++++
 src/proto/h1/role.rs |  4 ++++
 tests/server.rs      | 12 +++++++++---
 4 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/proto/h1/conn.rs b/src/proto/h1/conn.rs
index 8a5a734940..502e6c4922 100644
--- a/src/proto/h1/conn.rs
+++ b/src/proto/h1/conn.rs
@@ -707,7 +707,9 @@ where
                 // to do only speak HTTP/1.0 as well.
                 head.version = Version::HTTP_10;
             }
-            Version::HTTP_11 => {
+            // A 101 hands off the connection to another protocol, so disabled
+            // HTTP keep-alive must not add a close option to the upgrade response
+            Version::HTTP_11 if !T::is_switching_protocols(head) => {
                 if let KA::Disabled = self.state.keep_alive.status() {
                     match head.headers.entry(CONNECTION) {
                         Entry::Occupied(mut entry) => {
diff --git a/src/proto/h1/mod.rs b/src/proto/h1/mod.rs
index 344d5a8a4f..4587440bec 100644
--- a/src/proto/h1/mod.rs
+++ b/src/proto/h1/mod.rs
@@ -37,6 +37,10 @@ pub(crate) trait Http1Transaction {
 
     fn on_error(err: &crate::Error) -> Option<MessageHead<Self::Outgoing>>;
 
+    fn is_switching_protocols(_head: &MessageHead<Self::Outgoing>) -> bool {
+        false
+    }
+
     fn is_client() -> bool {
         !Self::is_server()
     }
diff --git a/src/proto/h1/role.rs b/src/proto/h1/role.rs
index fce1df78af..169919b102 100644
--- a/src/proto/h1/role.rs
+++ b/src/proto/h1/role.rs
@@ -510,6 +510,10 @@ impl Http1Transaction for Server {
         Some(msg)
     }
 
+    fn is_switching_protocols(head: &MessageHead<Self::Outgoing>) -> bool {
+        head.subject == StatusCode::SWITCHING_PROTOCOLS
+    }
+
     fn is_server() -> bool {
         true
     }
diff --git a/tests/server.rs b/tests/server.rs
index 094558cb61..261aa0d35c 100644
--- a/tests/server.rs
+++ b/tests/server.rs
@@ -1819,18 +1819,23 @@ async fn upgrades_new() {
             b"\
             GET / HTTP/1.1\r\n\
             Upgrade: foobar\r\n\
-            Connection: upgrade\r\n\
+            Connection: close, Upgrade\r\n\
             \r\n\
             eagerly optimistic\
         ",
         )
         .expect("write 1");
         let mut buf = [0; 256];
-        tcp.read(&mut buf).expect("read 1");
+        let response = read_until(&mut tcp, |buf| buf.ends_with(b"\r\n\r\n")).expect("read 1");
 
-        let response = s(&buf);
+        let response = s(&response);
         assert!(response.starts_with("HTTP/1.1 101 Switching Protocols\r\n"));
         assert!(!has_header(response, "content-length"));
+        assert!(
+            response.contains("\r\nconnection: upgrade\r\n"),
+            "{response}"
+        );
+        assert!(!response.contains("close"), "{response}");
         let _ = read_101_tx.send(());
 
         let n = tcp.read(&mut buf).expect("read 2");
@@ -1846,6 +1851,7 @@ async fn upgrades_new() {
             Response::builder()
                 .status(101)
                 .header("upgrade", "foobar")
+                .header("connection", "upgrade")
                 .body(Empty::<Bytes>::new())
                 .unwrap(),
         )