From 97ee3891f1187dfa8e6583cb6d2b4e1ca55d3d70 Mon Sep 17 00:00:00 2001
From: Denton Gentry <dgentry@tailscale.com>
Date: Sun, 15 Oct 2023 15:32:37 -0700
Subject: [PATCH] net/dns: use direct when NetworkManager has no
systemd-resolved
Endeavour OS, at least, uses NetworkManager 1.44.2 and does
not use systemd-resolved behind the scenes at all. If we
find ourselves in that situation, return "direct" not
"systemd-resolved"
Fixes https://github.com/tailscale/tailscale/issues/9687
Signed-off-by: Denton Gentry <dgentry@tailscale.com>
---
net/dns/manager_linux.go | 7 +++++++
net/dns/manager_linux_test.go | 12 ++++++++++++
2 files changed, 19 insertions(+)
diff --git a/net/dns/manager_linux.go b/net/dns/manager_linux.go
index 642fe99c5..75662d672 100644
--- a/net/dns/manager_linux.go
+++ b/net/dns/manager_linux.go
@@ -265,6 +265,13 @@ func dnsMode(logf logger.Logf, env newOSConfigEnv) (ret string, err error) {
dbg("nm-safe", "yes")
return "network-manager", nil
}
+ if err := env.nmIsUsingResolved(); err != nil {
+ // If systemd-resolved is not running at all, then we don't have any
+ // other choice: we take direct control of DNS.
+ dbg("nm-resolved", "no")
+ return "direct", nil
+ }
+
health.SetDNSManagerHealth(errors.New("systemd-resolved and NetworkManager are wired together incorrectly; MagicDNS will probably not work. For more info, see https://tailscale.com/s/resolved-nm"))
dbg("nm-safe", "no")
return "systemd-resolved", nil
diff --git a/net/dns/manager_linux_test.go b/net/dns/manager_linux_test.go
index c936d7b02..bbaa7ddc1 100644
--- a/net/dns/manager_linux_test.go
+++ b/net/dns/manager_linux_test.go
@@ -270,6 +270,18 @@ func TestLinuxDNSMode(t *testing.T) {
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
+ {
+ // regression test for https://github.com/tailscale/tailscale/issues/9687
+ name: "networkmanager_endeavouros",
+ env: env(resolvDotConf(
+ "# Generated by NetworkManager",
+ "search example.com localdomain",
+ "nameserver 10.0.0.1"),
+ nmRunning("1.44.2", false)),
+ wantLog: "dns: resolvedIsActuallyResolver error: resolv.conf doesn't point to systemd-resolved; points to [10.0.0.1]\n" +
+ "dns: [rc=nm resolved=not-in-use ret=direct]",
+ want: "direct",
+ },
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {