#!/bin/bash
# Setup TAP/Bridge networking for QEMU VM
# Bridge: 100.100.0.1/24
# VM will be: 100.100.0.2/24

set -e

# Create bridge if not exists
if ! ip link show br0 &>/dev/null; then
    ip link add br0 type bridge
    ip addr add 100.100.0.1/24 dev br0
    ip link set br0 up
    echo "Bridge br0 created with IP 100.100.0.1/24"
fi

# Create TAP device if not exists
if ! ip link show tap0 &>/dev/null; then
    ip tuntap add tap0 mode tap
    ip link set tap0 master br0
    ip link set tap0 up
    echo "TAP device tap0 created and attached to br0"
fi

# Enable IP forwarding
echo 1 > /proc/sys/net/ipv4/ip_forward

# Setup NAT/masquerade for outbound traffic from VM
iptables -t nat -C POSTROUTING -s 100.100.0.0/24 -o eth0 -j MASQUERADE 2>/dev/null ||     iptables -t nat -A POSTROUTING -s 100.100.0.0/24 -o eth0 -j MASQUERADE

# Forward traffic destined for VPN networks to VM (10.35.33.230 = IBM i)
# The VM will route this through its VPN tunnel
iptables -C FORWARD -d 10.35.33.230 -j ACCEPT 2>/dev/null ||     iptables -A FORWARD -d 10.35.33.230 -j ACCEPT
iptables -C FORWARD -s 10.35.33.230 -j ACCEPT 2>/dev/null ||     iptables -A FORWARD -s 10.35.33.230 -j ACCEPT

# Route to IBM i through VM
ip route add 10.35.33.230 via 100.100.0.2 2>/dev/null || true

echo "Network setup complete"
echo "Bridge: br0 = 100.100.0.1/24"
echo "TAP: tap0 attached to br0"
echo "Route: 10.35.33.230 via 100.100.0.2 (VM)"