#!/usr/bin/env bash
# script to build latest wireguard module and wg(8) utility
# DISCLAIMER: The logic used to retrieve the proper headers is fragile at best.

# exit if a command fails
set -o errexit

# display last non-zero exit code in a failed pipeline
set -o pipefail

# subshells and functions inherit ERR traps
set -E

# install dependencies if needed
sudo apt-get install -y libmnl-dev libelf-dev build-essential pkg-config

# create build directory
BUILD_DIR="$(mktemp -d)"

# remove the build directory on exit
function cleanup {
  rm -rf "${BUILD_DIR}"
}
trap cleanup EXIT

# retrieve debian codename
CODENAME="$(grep CODENAME /etc/os-release | cut -d"=" -f2)"

# retrieve kernel full version
KERNEL="$(uname -r)"

# retrieve kernel short version
KERNEL_SHORT="${KERNEL//-pve/}"

# download appropriate kernel headers
wget --directory-prefix="${BUILD_DIR}" http://download.proxmox.com/debian/pve/dists/"$CODENAME"/pve-no-subscription/binary-amd64/pve-headers-"${KERNEL}"_"${KERNEL_SHORT}"_amd64.deb

# install the kernel headers
sudo dpkg -i "${BUILD_DIR}"/pve-headers-"${KERNEL}"_"${KERNEL_SHORT}"_amd64.deb

# specify directory for wireguard module
MODULE_DIR="${BUILD_DIR}"/wireguard-linux-compat

# specify directory for wg(8)
TOOL_DIR="${BUILD_DIR}"/wireguard-tools

# clone the kernel module source
git clone https://git.zx2c4.com/wireguard-linux-compat "${MODULE_DIR}"

# clone the wg(8) utility source
git clone https://git.zx2c4.com/wireguard-tools "${TOOL_DIR}"

# compile and install the module
make -C "${MODULE_DIR}"/src -j"$(nproc)"
sudo make -C "${MODULE_DIR}"/src install

# compile and install wg(8)
make -C "${TOOL_DIR}"/src -j"$(nproc)"
sudo make -C "${TOOL_DIR}"/src install

# restart wireguard
sudo systemctl restart wg-quick@wg0