From c6d33c09fc2c60fe0ffb54464a550e1b7bd69c4c Mon Sep 17 00:00:00 2001 From: Amaury Denoyelle Date: Tue, 9 Sep 2025 15:34:25 +0200 Subject: [PATCH] BUG/MEDIUM: checks: fix ALPN inheritance from server If no specific check settings are defined on a server line, it is expected that these checks will be performed with the same parameters as normal connections on the same server. ALPN must be carefully taken into account for checks. Most notably, MUX initialization is delayed so that it is performed only after SSL handshake. Prior to this patch, MUX init delay was only performed if ALPN was defined via check settings. Thus, with the following settings, checks would be performed on HTTP/1.1 without consulting ALPN negotiation result from the server : server s1 127.0.0.1:443 ssl crt <...> alpn h2 check This bug may result in checks reporting failure, for example in case of a server answering HTTP/2 to ALPN negotiation to the configuration above. Besides, there is incoherency between normal and check connections, which is not what the documentation specifies. This patch fixes this code. Now server parameters are also taken into account. This ensures that checks and normal connections by default use the same connection method. This must be backported up to 2.4. --- src/tcpcheck.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/tcpcheck.c b/src/tcpcheck.c index b4b032ef0..ce82ea507 100644 --- a/src/tcpcheck.c +++ b/src/tcpcheck.c @@ -1512,7 +1512,7 @@ enum tcpcheck_eval_ret tcpcheck_eval_connect(struct check *check, struct tcpchec */ if (!s || ((connect->options & TCPCHK_OPT_DEFAULT_CONNECT) && check->mux_proto) || connect->mux_proto || - (!conn_is_ssl(conn) || (!connect->alpn && !check->alpn_str))) { + (!conn_is_ssl(conn) || (!connect->alpn && !check->alpn_str && !s->ssl_ctx.alpn_str))) { const struct mux_ops *mux_ops; TRACE_DEVEL("try to install mux now", CHK_EV_TCPCHK_CONN, check);