"Failed to set TOS for UDP Socket" for IPv6

[VVD]

Description

Fails to set TOS bits:

<W>2025-12-29 23:37:57.715 1 => Server listening on [::]:64738
<W>2025-12-29 23:37:57.721 1 => Server: Failed to set TOS for UDP Socket

This prevents proper QoS from being set for IPv6.
Downstream problem report: https://bugs.freebsd.org/292034

Steps to reproduce

1. Set in config host=:: or remove option host=.
2. Run: service mumble-server start.

Mumble version

1.5.857

Mumble component

Server

OS

FreeBSD

Reproducible?

Yes

Additional information

Patch:

--- src/murmur/Server.cpp.orig  2025-10-11 18:24:04 UTC
+++ src/murmur/Server.cpp
@@ -181,6 +181,15 @@ Server::Server(int snum, QObject *p) : QThread(p) {
                        } else {
 #ifdef Q_OS_UNIX
                                int val = 0xe0;
+#ifdef __FreeBSD__
+                               if (addr.ss_family == AF_INET6) {
+                                       if (setsockopt(sock, IPPROTO_IPV6, IPV6_TCLASS, &val, sizeof(val))) {
+                                               val = 0x80;
+                                               if (setsockopt(sock, IPPROTO_IPV6, IPV6_TCLASS, &val, sizeof(val)))
+                                                       log(QString("Server: Failed to set IPV6_TCLASS for UDP Socket, errno = ").arg(errno));
+                                       }
+                               } else
+#endif
                                if (setsockopt(sock, IPPROTO_IP, IP_TOS, &val, sizeof(val))) {
                                        val = 0x80;
                                        if (setsockopt(sock, IPPROTO_IP, IP_TOS, &val, sizeof(val)))

Relevant log output

<X>2025-12-29 23:37:57.698 SSL: OpenSSL version is 'OpenSSL 3.0.16 11 Feb 2025'
<W>2025-12-29 23:37:57.698 Initializing settings from /usr/local/etc/mumble/mumble-server.ini (basepath /usr/local/etc/mumble)
<W>2025-12-29 23:37:57.699 Binding to address ::
<C>2025-12-29 23:37:57.701 MetaParams: Adding 1 intermediate certificates from certificate file.
<W>2025-12-29 23:37:57.702 MetaParams: TLS cipher preference is "TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA:AES256-SHA:AES128-SHA"
<W>2025-12-29 23:37:57.706 ServerDB: Opened SQLite database /var/db/mumble-server/mumble-server.sqlite
<W>2025-12-29 23:37:57.707 ServerDB: Using SQLite's default rollback journal.
<W>2025-12-29 23:37:57.707 Murmur 1.5.0 running on FreeBSD: FreeBSD 14.3-RELEASE-p2 [x64]: Booting servers
<W>2025-12-29 23:37:57.715 1 => Server listening on [::]:64738
<W>2025-12-29 23:37:57.721 1 => Server: Failed to set TOS for UDP Socket

Screenshots

No response

[Hartmnt]

I wonder if this would also be the correct way to handle IPv6 sockets in Linux

[VVD]

If this is a question for me, then I don’t know…

[Hartmnt]

This is just a question in general. The author of the patch decided to guard the code for freebsd only. I wonder what's behind this, as I don't see why this would not apply to Linux at first glance. So that's a question for anyone who wants to investigate this and implement this bug fix.

[VVD]

The author of the patch decided to guard the code for freebsd only.

You can consider me the author of the patch. :-)

I wonder what's behind this, as I don't see why this would not apply to Linux at first glance.

I thought the link to the downstream problem report (https://bugs.freebsd.org/292034) answered this question: I'm a committer to FreeBSD ports and use it, so the patch was written and tested for FreeBSD.