#!/bin/bash
set -euo pipefail

BRIDGE_NAME="${BRIDGE_NAME:-br-rego-vpn}"
BRIDGE_CIDR="${BRIDGE_CIDR:-100.100.0.1}"
VM_NET_IP="${VM_NET_IP:-100.100.0.2}"
VM_MAC="${VM_MAC:-52:54:00:12:34:56}"

LEASE_TIME="${LEASE_TIME:-12h}"
DNS_SERVERS="${DNS_SERVERS:-1.1.1.1,8.8.8.8}"

if [[ "$BRIDGE_CIDR" != */* ]]; then
	BRIDGE_CIDR="$BRIDGE_CIDR/24"
fi

GATEWAY_IP="${BRIDGE_CIDR%%/*}"

mkdir -p /etc/dnsmasq.d

cat > /etc/dnsmasq.d/rego.conf <<EOF
interface=${BRIDGE_NAME}
bind-interfaces
except-interface=lo

dhcp-authoritative
log-dhcp

dhcp-range=${VM_NET_IP},${VM_NET_IP},${LEASE_TIME}
dhcp-option=option:router,${GATEWAY_IP}
dhcp-option=option:dns-server,${DNS_SERVERS}

# Static lease for the VM
# (VM must use DHCP for this to take effect)
dhcp-host=${VM_MAC},${VM_NET_IP}
EOF

echo "[rego-tunnel] dnsmasq on ${BRIDGE_NAME} gateway=${GATEWAY_IP} lease ${VM_MAC} -> ${VM_NET_IP}"
exec dnsmasq --no-daemon --conf-file=/etc/dnsmasq.d/rego.conf