From 7b6bfd2d78cfead3f1dfadbcedc92e4fbb24ff7c Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Thu, 25 Mar 2021 13:13:18 +0100
Subject: [PATCH] multi: close the connection when h2=>h1 downgrading

Otherwise libcurl is likely to reuse the connection again in the next
attempt since the connection reuse logic doesn't take downgrades into
account.

Reported-by: Anthony Ramine
Fixes #6788
Closes #6793
---
 lib/multi.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/multi.c b/lib/multi.c
index f5bacc17cb..5de4793225 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -2158,6 +2158,7 @@ static CURLMcode multi_runsingle(struct Curl_multi *multi,
 
         if(!ret) {
           infof(data, "Downgrades to HTTP/1.1!\n");
+          connclose(data->conn, "Disconnect HTTP/2 for HTTP/1");
           data->state.httpwant = CURL_HTTP_VERSION_1_1;
           /* clear the error message bit too as we ignore the one we got */
           data->state.errorbuf = FALSE;
-- 
2.47.3