services-xbee_net/scripts/entrypoint.sh

#!/bin/bash

# entrypoint.sh
#
# This script is responsible for setting up and maintaining an XBee network interface within a Docker container. 
# It performs several key tasks, including checking for root privileges, setting up the XBee network interface, 
# configuring network bridges, and monitoring both the XBee device and Wi-Fi interface for connectivity. 
# The script runs in a loop to ensure continuous operation, retrying the setup process if any steps fail.
#
# Usage:
# - This script is intended to be run as the entrypoint for a Docker container.
# - Ensure that the script has executable permissions (`chmod +x entrypoint.sh`) before running it.

# Source the get_connected_wifi_info.sh script
source /scripts/get_connected_wifi_info.sh

# Check if the script is running with root privileges
check_root() {
    if [ "$(id -u)" -ne 0 ]; then
        echo "This script must be run as root. Exiting..."
        exit 1
    fi
}

# Clean up resources
# - Kill the background process used to create the xbnet interface
# - Clean up any resources created or copied over. This includes:
#   - Bridge interface
#   - xbnet interface
cleanup() {
    echo "Cleaning up resources..."
    pkill -f "xbnet -d --serial-speed $XBEE_BAUDRATE $XBEE_PORT tap"

    if ip link show br0 > /dev/null 2>&1; then
        ip link set br0 down
        brctl delbr br0
    fi

    if ip link show $XBEE_NET_IFACE_NAME > /dev/null 2>&1; then
        ip link set $XBEE_NET_IFACE_NAME down
        ip link delete $XBEE_NET_IFACE_NAME
    fi
}

# Function to check if the XBee device is connected
# - Ensures that the XBee device is present at the specified port before proceeding
check_xbee_device() {
    if [ -e "$XBEE_PORT" ]; then
        echo "XBee device found at $XBEE_PORT. Proceeding with setup..."
        return 0
    else
        echo "Error: No XBee device found at $XBEE_PORT. Please connect the device."
        return 1
    fi
}

# Start the xbnet interface
# - Attempts to start the xbnet interface in tap mode
# - Verifies if the interface is successfully created and returns the appropriate status code
start_xbnet_interface() {
    echo "Starting XBee network interface..."
    xbnet -d --serial-speed $XBEE_BAUDRATE $XBEE_PORT tap &

    # Wait until the xbnet interface is created
    while [ ! -d "/sys/class/net/$XBEE_NET_IFACE_NAME" ]; do
        echo "Waiting for interface $XBEE_NET_IFACE_NAME to be created..."
        sleep 1
    done

    # Get the xbnet interface name (e.g., xbnet0) automatically
    XBEE_NET_IFACE_NAME=$(ls /sys/class/net | grep 'xbnet')

    # Check if the xbnet interface is found
    if [ -z "$XBEE_NET_IFACE_NAME" ]; then
        echo "Error: No XBee network interface found. Retrying setup..."
        cleanup
        return 1
    else
        echo "XBee network interface $XBEE_NET_IFACE_NAME created successfully."
        return 0
    fi
}

# Configure the network interface and bridge
# - Creates the network interface with the name specified by XBEE_NET_IFACE_NAME in .env file
# - Creates a bridge interface and attaches the xbnet interface to it
# - Brings up the bridge interface
configure_network_and_bridge() {
    ip addr add $XBEE_NET_SRC_IP/24 dev $XBEE_NET_IFACE_NAME
    ip link set dev $XBEE_NET_IFACE_NAME up

    brctl addbr br0
    brctl addif br0 $XBEE_NET_IFACE_NAME
    ip link set dev br0 up
}

# Monitor and bridge Wi-Fi
# - Continuously checks for a connected Wi-Fi interface
# - Bridges the Wi-Fi interface with the xbnet interface when found
# - If no Wi-Fi interface is found, continues checking every 5 seconds
monitor_and_bridge_wifi() {
    while true; do
        HOST_WIFI_IFACE=$(get_connected_wifi_device)
        
        if [ -n "$HOST_WIFI_IFACE" ]; then
            echo "Wi-Fi interface found: $HOST_WIFI_IFACE. Bridging with $XBEE_NET_IFACE_NAME..."
            brctl addif br0 $HOST_WIFI_IFACE

            iptables -t nat -A POSTROUTING -o $HOST_WIFI_IFACE -j MASQUERADE
            iptables -A FORWARD -i br0 -o $HOST_WIFI_IFACE -j ACCEPT
            iptables -A FORWARD -i $HOST_WIFI_IFACE -o br0 -j ACCEPT

            echo "Bridge configured. Monitoring for changes..."
            break
        else
            echo "No Wi-Fi interface found. Rechecking in 5 seconds..."
            sleep 5
        fi
    done
}

# Function to monitor the XBee device and restart setup if disconnected
# - Periodically checks if the XBee device is still connected
# - If the device is disconnected, triggers cleanup and restarts the setup process
monitor_xbee_device() {
    while [ -e "$XBEE_PORT" ]; do
        sleep 5
    done

    echo "XBee device at $XBEE_PORT was removed. Cleaning up..."
    cleanup
}

# Main function to set up the XBee network
# - Runs the setup process in a loop to ensure continuous operation
# - If any step fails, it retries the entire process after a short delay
setup_xbee_network() {
    while true; do
        check_xbee_device
        if [ $? -ne 0 ]; then
            sleep 5
            continue
        fi

        start_xbnet_interface
        if [ $? -ne 0 ]; then
            cleanup
            sleep 5
            continue
        fi

        configure_network_and_bridge
        monitor_and_bridge_wifi
        monitor_xbee_device
    done
}

# Run the setup only if the script is executed as root
check_root
setup_xbee_network