From: Christopher Faulet <cfaulet@haproxy.com>
Date: Thu, 7 Apr 2022 08:19:46 +0000 (+0200)
Subject: BUG/MEDIUM: promex: Be sure to never set EOM flag on an empty HTX message
X-Git-Tag: v2.6-dev5~31
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=be69cbdafe5a2a7939efe092b3c239eaf776c898;p=thirdparty%2Fhaproxy.git

BUG/MEDIUM: promex: Be sure to never set EOM flag on an empty HTX message

It is the same bug than "BUG/MEDIUM: stats: Be sure to never set EOM flag on
an empty HTX message". We must be sure to set the EOM flag on a non empyt
message to be sure the mux on the client will properly handle
shutdowns. Otherwise, it may miss the end of the message and considers any
shutdown as an abort.

This patch must be backported as far as 2.4. On previous version there is
still the EOM HTX block.
---

diff --git a/addons/promex/service-prometheus.c b/addons/promex/service-prometheus.c
index 06eb1eea9b..48bf1602d6 100644
--- a/addons/promex/service-prometheus.c
+++ b/addons/promex/service-prometheus.c
@@ -1509,8 +1509,20 @@ static void promex_appctx_handle_io(struct appctx *appctx)
 			/* fall through */
 
 		case PROMEX_ST_DONE:
-			/* no more data are expected. Don't add TLR because mux-h1 will take care of it */
-			res_htx->flags |= HTX_FL_EOM;
+			/* no more data are expected. If the response buffer is
+			 * empty, be sure to add something (EOT block in this
+			 * case) to have something to send. It is important to
+			 * be sure the EOM flags will be handled by the
+			 * endpoint.
+			 */
+			if (htx_is_empty(res_htx)) {
+				if (!htx_add_endof(res_htx, HTX_BLK_EOT)) {
+					si_rx_room_blk(si);
+					goto out;
+				}
+				channel_add_input(res, 1);
+			}
+		        res_htx->flags |= HTX_FL_EOM;
 			si->cs->flags |= CS_FL_EOI;
 			res->flags |= CF_EOI;
 			appctx->st0 = PROMEX_ST_END;