rego-tunnel: parameterize net + add DHCP static lease

apps/rego-tunnel/build/start-dnsmasq.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+set -euo pipefail
+
+BRIDGE_NAME="${BRIDGE_NAME:-br-rego-vpn}"
+BRIDGE_CIDR="${BRIDGE_CIDR:-100.100.0.1/24}"
+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}"
+
+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