wg-quick: add explicit support for common DNS usage

1 files changed, 16 insertions, 0 deletions

diff --git a/src/tools/wg-quick.bash b/src/tools/wg-quick.bash
index d7e7d68..e5ae48f 100755
--- a/src/tools/wg-quick.bash
+++ b/src/tools/wg-quick.bash
@@ -14,6 +14,7 @@ WG_CONFIG=""
 INTERFACE=""
 ADDRESSES=( )
 MTU=""
+DNS=( )
 PRE_UP=""
 POST_UP=""
 PRE_DOWN=""
@@ -41,6 +42,7 @@ parse_options() {
 			case "$key" in
 			Address) ADDRESSES+=( ${value//,/ } ); continue ;;
 			MTU) MTU="$value"; continue ;;
+			DNS) DNS+=( ${value//,/ } ); continue ;;
 			PreUp) PRE_UP="$value"; continue ;;
 			PreDown) PRE_DOWN="$value"; continue ;;
 			PostUp) POST_UP="$value"; continue ;;
@@ -128,6 +130,14 @@ set_mtu() {
 	cmd ip link set mtu $(( mtu - 80 )) dev "$INTERFACE"
 }
 
+set_dns() {
+	[[ ${#DNS[@]} -eq 0 ]] || printf 'nameserver %s\n' "${DNS[@]}" | cmd resolvconf -a "tun.$INTERFACE" -m 0 -x
+}
+
+unset_dns() {
+	[[ ${#DNS[@]} -eq 0 ]] || cmd resolvconf -d "tun.$INTERFACE"
+}
+
 add_route() {
 	if [[ $1 == 0.0.0.0/0 || $1 =~ ^[0:]+/0$ ]]; then
 		add_default "$1"
@@ -168,6 +178,9 @@ save_config() {
 	for address in ${BASH_REMATCH[1]}; do
 		new_config+="Address = $address"$'\n'
 	done
+	while read -r address; do
+		[[ $address =~ ^nameserver\ ([a-zA-Z0-9_=+:%.-]+)$ ]] && new_config+="DNS = ${BASH_REMATCH[1]}"$'\n'
+	done < <(resolvconf -l "tun.$INTERFACE" 2>/dev/null)
 	[[ -n $MTU && $(ip link show dev "$INTERFACE") =~ mtu\ ([0-9]+) ]] && new_config+="MTU = ${BASH_REMATCH[1]}"$'\n'
 	[[ $SAVE_CONFIG -eq 0 ]] || new_config+=$'SaveConfig = true\n'
 	[[ -z $PRE_UP ]] || new_config+="PreUp = $PRE_UP"$'\n'
@@ -203,6 +216,7 @@ cmd_usage() {
 
 	  - Address: may be specified one or more times and contains one or more
 	    IP addresses (with an optional CIDR mask) to be set for the interface.
+	  - DNS: an optional DNS server to use while the device is up.
 	  - MTU: an optional MTU for the interface; if unspecified, auto-calculated.
 	  - PreUp, PostUp, PreDown, PostDown: script snippets which will be executed
 	    by bash(1) at the corresponding phases of the link, most commonly used
@@ -226,6 +240,7 @@ cmd_up() {
 	done
 	set_mtu
 	up_if
+	set_dns
 	for i in $(while read -r _ i; do for i in $i; do [[ $i =~ ^[0-9a-z:.]+/[0-9]+$ ]] && echo "$i"; done; done < <(wg show "$INTERFACE" allowed-ips) | sort -nr -k 2 -t /); do
 		[[ $(ip route get "$i" 2>/dev/null) == *dev\ $INTERFACE\ * ]] || add_route "$i"
 	done
@@ -237,6 +252,7 @@ cmd_down() {
 	[[ -n $(ip link show dev "$INTERFACE" type wireguard 2>/dev/null) ]] || die "\`$INTERFACE' is not a WireGuard interface"
 	execute_hook "$PRE_DOWN"
 	[[ $SAVE_CONFIG -eq 0 ]] || save_config
+	unset_dns
 	del_if
 	execute_hook "$POST_DOWN"
 }