From 94744c77a9a66b06041c06ca6b0b4903366e5b5c Mon Sep 17 00:00:00 2001
From: DerDanilo <DerDanilo@notsharingmymail>
Date: Mon, 15 Mar 2021 18:03:05 +0100
Subject: [PATCH] add Wireguard MTU support via setupVARS.conf

---
 auto_install/install.sh                    |  8 ++++++++
 examples/unattended_wireguard_example.conf |  1 +
 scripts/wireguard/makeCONF.sh              | 10 +++++++---
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/auto_install/install.sh b/auto_install/install.sh
index 7c2104f..3acadcb 100755
--- a/auto_install/install.sh
+++ b/auto_install/install.sh
@@ -1083,6 +1083,12 @@ installPiVPN(){
 		pivpnDEV="wg0"
 		pivpnNET="10.6.0.0"
 		vpnGw="${pivpnNET/.0.0/.0.1}"
+		# The default MTU should be fine for most users but we allow to set a
+		# custom MTU via unattend setupVARs file. Use default if not provided.
+		if [ -z "$pivpnMTU" ]; then
+			# Using default Wireguard MTU
+			pivpnMTU="1420"
+		fi
 		# Forward all traffic through PiVPN (i.e. full-tunnel), may be modified by
 		# the user after the installation.
 		ALLOWED_IPS="0.0.0.0/0, ::0/0"
@@ -1096,6 +1102,7 @@ installPiVPN(){
 		confNetwork
 
 		echo "pivpnPROTO=${pivpnPROTO}" >> ${tempsetupVarsFile}
+		echo "pivpnMTU=${pivpnMTU}" >> ${tempsetupVarsFile}
 
 	fi
 
@@ -2047,6 +2054,7 @@ confWireGuard(){
 	echo "[Interface]
 PrivateKey = $($SUDO cat /etc/wireguard/keys/server_priv)
 Address = ${vpnGw}/${subnetClass}
+MTU = ${pivpnMTU}
 ListenPort = ${pivpnPORT}" | $SUDO tee /etc/wireguard/wg0.conf &> /dev/null
 	echo "::: Server config generated."
 }
diff --git a/examples/unattended_wireguard_example.conf b/examples/unattended_wireguard_example.conf
index e417927..700a3e0 100644
--- a/examples/unattended_wireguard_example.conf
+++ b/examples/unattended_wireguard_example.conf
@@ -4,6 +4,7 @@ IPv4gw=192.168.23.1
 dhcpReserv=0
 install_user=pi
 VPN=wireguard
+pivpnMTU=1420
 pivpnPORT=51820
 pivpnDNS1=9.9.9.9
 pivpnDNS2=149.112.112.112
diff --git a/scripts/wireguard/makeCONF.sh b/scripts/wireguard/makeCONF.sh
index 73bfd9b..9ca07cc 100755
--- a/scripts/wireguard/makeCONF.sh
+++ b/scripts/wireguard/makeCONF.sh
@@ -94,11 +94,15 @@ done
 
 NET_REDUCED="${pivpnNET::-2}"
 
-echo -n "[Interface]
+echo "[Interface]
 PrivateKey = $(cat "keys/${CLIENT_NAME}_priv")
-Address = ${NET_REDUCED}.${COUNT}/${subnetClass}
-DNS = ${pivpnDNS1}" > "configs/${CLIENT_NAME}.conf"
+Address = ${NET_REDUCED}.${COUNT}/${subnetClass}" > "configs/${CLIENT_NAME}.conf"
 
+if [ -n "${pivpnMTU}" ]; then
+    echo "MTU = ${pivpnMTU}" >> "configs/${CLIENT_NAME}.conf"
+fi
+
+echo -n "DNS = ${pivpnDNS1}" >> "configs/${CLIENT_NAME}.conf"
 if [ -n "${pivpnDNS2}" ]; then
     echo ", ${pivpnDNS2}" >> "configs/${CLIENT_NAME}.conf"
 else