From: Christopher Faulet <cfaulet@haproxy.com>
Date: Wed, 22 Apr 2026 14:40:55 +0000 (+0200)
Subject: BUG/MINOR: mux-h1: Fix condition to send null-chunk for bodyless message
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=392abee6d4fc6e86488829ea40ad8dbbbb35ba71;p=thirdparty%2Fhaproxy.git

BUG/MINOR: mux-h1: Fix condition to send null-chunk for bodyless message

When the EOH block is processed, before sending message headers, there is a
test to know if there is no payload. In case of a chunked message, a
null-chunk is emitted, except for bodyless response. For instance, a
response to a HEAD request has no payload at all and no null-chunk.

However, the test for bodyless responses is not correct. Only
H1S_F_BODYLESS_RESP flag is tested. But this flag can be set on server side
when we are processing the request. To fix the issue, the test was
adapted. The null-chunk is added if a message with no payload is chunked and
it is a request or a non-bodyless responses.

This patch must be backported to all stable version.
---

diff --git a/src/mux_h1.c b/src/mux_h1.c
index eaf9f43c8..b05ddcc9a 100644
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -2988,7 +2988,8 @@ static size_t h1_make_eoh(struct h1s *h1s, struct h1m *h1m, struct htx *htx, siz
 		 * payload. If cannot be removed now. We must emit the end of
 		 * the message first to be sure the output buffer is not full
 		 */
-		if ((h1m->flags & H1_MF_CHNK) && !(h1s->flags & H1S_F_BODYLESS_RESP)) {
+		if ((h1m->flags & H1_MF_CHNK) && (!(h1m->flags & H1_MF_RESP) || !(h1s->flags & H1S_F_BODYLESS_RESP))) {
+			/* Send null-chunk except for bodyless reasponses */
 			if (!chunk_memcat(&outbuf, "\r\n0\r\n\r\n", 7))
 				goto full;
 		}