From 04a8b8bb8e0739ce8e795705920de64d80e52c8f Mon Sep 17 00:00:00 2001 From: Galen Guyer Date: Wed, 11 Oct 2023 11:08:08 -0400 Subject: [PATCH] net/dns: properly detect newer debian resolvconf Tailscale attempts to determine if resolvconf or openresolv is in use by running `resolvconf --version`, under the assumption this command will error when run with Debian's resolvconf. This assumption is no longer true and leads to the wrong commands being run on newer versions of Debian with resolvconf >= 1.90. We can now check if the returned version string starts with "Debian resolvconf" if the command is successful. Fixes #9218 Signed-off-by: Galen Guyer --- net/dns/resolvconf.go | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/dns/resolvconf.go b/net/dns/resolvconf.go index 0304375ee..ca584ffcc 100644 --- a/net/dns/resolvconf.go +++ b/net/dns/resolvconf.go @@ -6,6 +6,7 @@ package dns import ( + "bytes" "os/exec" ) @@ -13,13 +14,17 @@ func resolvconfStyle() string { if _, err := exec.LookPath("resolvconf"); err != nil { return "" } - if _, err := exec.Command("resolvconf", "--version").CombinedOutput(); err != nil { + output, err := exec.Command("resolvconf", "--version").CombinedOutput() + if err != nil { // Debian resolvconf doesn't understand --version, and // exits with a specific error code. if exitErr, ok := err.(*exec.ExitError); ok && exitErr.ExitCode() == 99 { return "debian" } } + if bytes.HasPrefix(output, []byte("Debian resolvconf")) { + return "debian" + } // Treat everything else as openresolv, by far the more popular implementation. return "openresolv" }