From: Christopher Faulet <cfaulet@haproxy.com>
Date: Tue, 8 Jul 2025 05:46:26 +0000 (+0200)
Subject: BUG/MEDIUM: http-client: Don't wake http-client applet if nothing was xferred
X-Git-Tag: v3.3-dev3~15
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fffdac42df4848420028f89b14c2a90c12dbf9ab;p=thirdparty%2Fhaproxy.git

BUG/MEDIUM: http-client: Don't wake http-client applet if nothing was xferred

When data are transferred to or from the htt-pclient, the applet is
systematically woken up, even when no data are transferred. This could lead
to needlessly wakeups. When called from a lua script, if data are blocked
for a while, this leads to a wakeup ping-pong loop where the http-client
applet is woken up by the lua script which wakes back the script.

To fix the issue, in httpclient_req_xfer() and httpclient_res_xfer()
functions, we now take care to not wake the http-client applet up when no
data are transferred.

This patch must be backported as far as 2.6.
---

diff --git a/src/http_client.c b/src/http_client.c
index f061b230b..47d73e004 100644
--- a/src/http_client.c
+++ b/src/http_client.c
@@ -179,10 +179,11 @@ int httpclient_res_xfer(struct httpclient *hc, struct buffer *dst)
 	int ret;
 
 	ret = b_force_xfer(dst, &hc->res.buf, MIN(room, b_data(&hc->res.buf)));
+
 	/* call the client once we consumed all data */
 	if (!b_data(&hc->res.buf)) {
 		b_free(&hc->res.buf);
-		if (hc->appctx)
+		if (ret && hc->appctx)
 			appctx_wakeup(hc->appctx);
 	}
 	return ret;
@@ -211,11 +212,10 @@ int httpclient_req_xfer(struct httpclient *hc, struct ist src, int end)
 	if (!htx)
 		goto error;
 
-	if (hc->appctx)
-		appctx_wakeup(hc->appctx);
-
 	ret += htx_add_data(htx, src);
 
+	if (ret && hc->appctx)
+		appctx_wakeup(hc->appctx);
 
 	/* if we copied all the data and the end flag is set */
 	if ((istlen(src) == ret) && end) {