Update dependencies

vendor/tailscale.com/net/dns/resolvconf-workaround.sh

@@ -0,0 +1,62 @@
+#!/bin/sh
+# Copyright (c) Tailscale Inc & AUTHORS
+# SPDX-License-Identifier: BSD-3-Clause
+#
+# 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