diff mbox series

[Openvpn-devel,v4] mac dns: do not run dns-updown in parallel

Message ID 20250711100700.241668-1-frank@lichtenheld.com
State New
Headers show
Series [Openvpn-devel,v4] mac dns: do not run dns-updown in parallel | expand

Commit Message

Frank Lichtenheld July 11, 2025, 10:07 a.m. UTC 
From: Heiko Hund <heiko@ist.eigentlich.net>

In case more than one openvpn connection is coming up or going down at
the same time, there is potential for breakage, since the operations
performed are not atomic.

Introduce a locking mechanism, which let's scripts run in sequence, to
prevent races between them.

Change-Id: I7adfaa08df6a17545cca8264d7230b5e65e49719
Signed-off-by: Heiko Hund <heiko@ist.eigentlich.net>
Acked-by: Arne Schwabe <arne-openvpn@rfc2549.org>
---

This change was reviewed on Gerrit and approved by at least one
developer. I request to merge it to master.

Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1076
This mail reflects revision 4 of this Change.

Acked-by according to Gerrit (reflected above):
Arne Schwabe <arne-openvpn@rfc2549.org>

Comments

Gert Doering July 15, 2025, 2:09 p.m. UTC | #1 
Locking good :-) - and the code looks quite reasonable.

Your patch has been applied to the master branch.

commit bc2c74291b8fce3f7a64346753d56f18cd182886
Author: Heiko Hund
Date:   Fri Jul 11 12:07:00 2025 +0200

     mac dns: do not run dns-updown in parallel

     Signed-off-by: Heiko Hund <heiko@ist.eigentlich.net>
     Acked-by: Arne Schwabe <arne-openvpn@rfc2549.org>
     Message-Id: <20250711100700.241668-1-frank@lichtenheld.com>
     URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg32108.html
     Signed-off-by: Gert Doering <gert@greenie.muc.de>


--
kind regards,

Gert Doering
diff mbox series

Patch

diff --git a/distro/dns-scripts/macos-dns-updown.sh b/distro/dns-scripts/macos-dns-updown.sh
index 73bbee9..fb17b2b0 100644
--- a/distro/dns-scripts/macos-dns-updown.sh
+++ b/distro/dns-scripts/macos-dns-updown.sh
@@ -26,6 +26,23 @@ 
 #   dns_server_1_sni dns.mycorp.in
 #
 
+lockdir=/var/lock
+if [ ! -d "${lockdir}" ]; then
+    /bin/mkdir "${lockdir}"
+    /bin/chmod 1777 "${lockdir}"
+fi
+
+i=1
+lockfile="${lockdir}/openvpn-dns-updown.lock"
+while ! /usr/bin/shlock -f $lockfile -p $$; do
+    if [ $((++i)) -gt 10 ]; then
+        echo "dns-updown failed, could not acquire lock"
+        exit 1
+    fi
+    sleep 0.2
+done
+trap "/bin/rm -f ${lockfile}" EXIT
+
 [ -z "${dns_vars_file}" ] || . "${dns_vars_file}"
 
 itf_dns_key="State:/Network/Service/openvpn-${dev}/DNS"