From: Christopher Faulet <cfaulet@haproxy.com>
Date: Wed, 15 Jul 2020 13:46:30 +0000 (+0200)
Subject: BUG/MINOR: mux-fcgi: Handle empty STDERR record
X-Git-Tag: v2.3-dev1~17
X-Git-Url: http://git.haproxy.org/?a=commitdiff_plain;h=7f85433a912529c5cda1629001b34fd2b2e54758;p=haproxy-2.5.git

BUG/MINOR: mux-fcgi: Handle empty STDERR record

As mentionned in the FastCGI specification, FCGI "streams" are series of
non-empty stream records (length != 0), followed by an empty one. It is properly
handled for FCGI_STDOUT records, but not for FCGI_STDERR ones. If an empty
FCGI_STDERR record is received, the connection is blocked waiting for data which
will never come.

To fix the bug, when an empty FCGI_STDERR record is received, we drop it, eating
the padding if any.

This patch should fix the issue #743. It must be backported as far as 2.1.
---

diff --git a/src/mux_fcgi.c b/src/mux_fcgi.c
index 58d4923..d1094d9 100644
--- a/src/mux_fcgi.c
+++ b/src/mux_fcgi.c
@@ -2355,7 +2355,7 @@ static int fcgi_strm_handle_stderr(struct fcgi_conn *fconn, struct fcgi_strm *fs
 	dbuf = &fconn->dbuf;
 
 	/* Only padding remains */
-	if (fconn->state == FCGI_CS_RECORD_P)
+	if (fconn->state == FCGI_CS_RECORD_P || !fconn->drl)
 		goto end_transfer;
 
 	if (b_data(dbuf) < (fconn->drl + fconn->drp) &&