mirror of
https://github.com/tailscale/tailscale.git
synced 2024-12-12 03:04:40 +00:00
64 lines
2.3 KiB
Bash
64 lines
2.3 KiB
Bash
#!/bin/sh
|
|
# Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
|
|
# Use of this source code is governed by a BSD-style
|
|
# license that can be found in the LICENSE file.
|
|
#
|
|
# This script is a workaround for a vpn-unfriendly behavior of the
|
|
# original resolvconf by Thomas Hood. Unlike the `openresolv`
|
|
# implementation (whose binary is also called resolvconf,
|
|
# confusingly), the original resolvconf lacks a way to specify
|
|
# "exclusive mode" for a provider configuration. In practice, this
|
|
# means that if Tailscale wants to install a DNS configuration, that
|
|
# config will get "blended" with the configs from other sources,
|
|
# rather than override those other sources.
|
|
#
|
|
# This script gets installed at /etc/resolvconf/update-libc.d, which
|
|
# is a directory of hook scripts that get run after resolvconf's libc
|
|
# helper has finished rewriting /etc/resolv.conf. It's meant to notify
|
|
# consumers of resolv.conf of a new configuration.
|
|
#
|
|
# Instead, we use that hook mechanism to reach into resolvconf's
|
|
# stuff, and rewrite the libc-generated resolv.conf to exclusively
|
|
# contain Tailscale's configuration - effectively implementing
|
|
# exclusive mode ourselves in post-production.
|
|
|
|
set -e
|
|
|
|
if [ -n "$TAILSCALE_RESOLVCONF_HOOK_LOOP" ]; then
|
|
# Hook script being invoked by itself, skip.
|
|
exit 0
|
|
fi
|
|
|
|
if [ ! -f tun-tailscale.inet ]; then
|
|
# Tailscale isn't trying to manage DNS, do nothing.
|
|
exit 0
|
|
fi
|
|
|
|
if ! grep resolvconf /etc/resolv.conf >/dev/null; then
|
|
# resolvconf isn't managing /etc/resolv.conf, do nothing.
|
|
exit 0
|
|
fi
|
|
|
|
# Write out a modified /etc/resolv.conf containing just our config.
|
|
(
|
|
if [ -f /etc/resolvconf/resolv.conf.d/head ]; then
|
|
cat /etc/resolvconf/resolv.conf.d/head
|
|
fi
|
|
echo "# Tailscale workaround applied to set exclusive DNS configuration."
|
|
cat tun-tailscale.inet
|
|
if [ -f /etc/resolvconf/resolv.conf.d/base ]; then
|
|
# Keep options and sortlist, discard other base things since
|
|
# they're the things we're trying to override.
|
|
grep -e 'sortlist ' -e 'options ' /etc/resolvconf/resolv.conf.d/base || true
|
|
fi
|
|
if [ -f /etc/resolvconf/resolv.conf.d/tail ]; then
|
|
cat /etc/resolvconf/resolv.conf.d/tail
|
|
fi
|
|
) >/etc/resolv.conf
|
|
|
|
if [ -d /etc/resolvconf/update-libc.d ] ; then
|
|
# Re-notify libc watchers that we've changed resolv.conf again.
|
|
export TAILSCALE_RESOLVCONF_HOOK_LOOP=1
|
|
exec run-parts /etc/resolvconf/update-libc.d
|
|
fi
|