#!/bin/sh
# 2021-04-27

echo BUG: cannot use more than one due to port assignment
echo All WG IPv4 have same source port

if [ $# -lt 2 ]; then
    echo "$0 host ipv4-address interface [private-key]"
    echo "    host: where to find the OpenWRT device"
    echo "    ipv4-address: which ipv4 address to use"
    echo "    private-key: Use this wireguard key instead of generating one"
    echo ""
    echo "f.i.: $0 2a0a:e5c1:6XX:cafe::42 185.155.a.b"
    exit 1
fi

my_ip=$1; shift
my_wireguard_ip=$1; shift

if [ $# -eq 1 ]; then
    private_key=$1; shift
else
    private_key=$(wg genkey)
fi
public_key=$(echo $private_key | wg pubkey)

case $my_wireguard_ip in
    185.155.29.*)
        vpn_endpoint_pubkey="6BRnQ+dmeFzVCH9RbM1pbJ7u3y3qrl+zUzzYCmC88kE="
    ;;
    185.155.30.*)
        vpn_endpoint_pubkey="5ach7pUQ57aa402LHz1MYh7lyBZS0GvBEw2PC6dMHW4="
        ;;
    *)
        echo "Unknown VPN host for IP $my_wireguard_ip" >&2
        exit 1
        ;;
esac

interface="ip$(echo $my_wireguard_ip | awk -F. '{ print $1 $2 $3 $4 }')"
vpn_endpoint_host=vpn-$(echo $my_wireguard_ip | awk -F. '{ print $1 $2 $3 }').ungleich.ch

cat <<EOF | ssh -t "root@${my_ip}"
set -x

opkg update
opkg install libustream-openssl ca-bundle ca-certificates
opkg install wireguard
opkg install luci-app-wireguard

uci set network.${interface}=interface
uci set network.${interface}.proto='wireguard'
uci set network.${interface}.private_key='${private_key}'
uci set network.${interface}.listen_port='51828'
uci set network.${interface}.addresses='${my_wireguard_ip}/32'

if ! uci get network.@wireguard_${interface}[0]; then
   uci add network wireguard_${interface}
fi

uci set network.@wireguard_${interface}[0]=wireguard_${interface}
uci set network.@wireguard_${interface}[0].persistent_keepalive='25'
uci set network.@wireguard_${interface}[0].public_key="${vpn_endpoint_pubkey}"
uci set network.@wireguard_${interface}[0].description="IPv4 as a service by ungleich"
uci set network.@wireguard_${interface}[0].allowed_ips='0.0.0.0/0'
uci set network.@wireguard_${interface}[0].endpoint_host="${vpn_endpoint_host}"
uci set network.@wireguard_${interface}[0].endpoint_port='51820'
uci set network.@wireguard_${interface}[0].route_allowed_ips='1'

# add to correct firewall zone
current_networks=\$(uci get firewall.@zone[1].network)

if ! echo \$current_networks | grep -q ${interface}; then
   uci set firewall.@zone[1].network="\${current_networks} ${interface}"
fi

# commit
uci commit

EOF

echo "Host ${my_ip} uses ip ${my_wireguard_ip} with public key ${public_key}:"

cat <<EOF

#
[Peer]
PublicKey = ${public_key}
AllowedIPs = ${my_wireguard_ip}/32
EOF