From: Willy Tarreau <w@1wt.eu>
Date: Wed, 16 Feb 2022 13:28:14 +0000 (+0100)
Subject: BUG/MEDIUM: h2/hpack: fix emission of HPACK DTSU after settings change
X-Git-Tag: v2.6-dev2~118
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c7d85485a00bd9862ecb726ad1242c2ba724a8ca;p=thirdparty%2Fhaproxy.git

BUG/MEDIUM: h2/hpack: fix emission of HPACK DTSU after settings change

Sadly, despite particular care, commit 39a0a1e12 ("MEDIUM: h2/hpack: emit
a Dynamic Table Size Update after settings change") broke H2 when sending
DTSU. A missing negation on the flag caused the DTSU_EMITTED flag to be
lost and the DTSU to be sent again on the next stream, and possibly to
break flow control or a few other internal states.

This will have to be backported wherever the patch above was backported.

Thanks to Yves Lafon for notifying us with elements to reproduce the
issue!
---

diff --git a/src/mux_h2.c b/src/mux_h2.c
index 3b055b44e7..7e50aa55ab 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -5259,7 +5259,7 @@ static size_t h2s_frt_make_resp_headers(struct h2s *h2s, struct htx *htx)
 	if (h2c->flags & H2_CF_SHTS_UPDATED) {
 		/* was sent above */
 		h2c->flags |= H2_CF_DTSU_EMITTED;
-		h2c->flags &= H2_CF_SHTS_UPDATED;
+		h2c->flags &= ~H2_CF_SHTS_UPDATED;
 	}
 
 	if (es_now) {