#!/bin/bash
apt install -y bridge-utils
# The IP address shared by the USB network interface creatoedd by this script.
NET_IP="192.168.55.1"
# The associated netmask.
NET_MASK="255.255.0.0"

# 定义USB Gadget的根目录，使用官网脚本的通用名称 "pi4"
GADGET_NAME="pi4"
GADGET_ROOT="/sys/kernel/config/usb_gadget/${GADGET_NAME}"

# --- UDC DEVICE 提示 ---
# 通常 Raspberry Pi (或类似SoC) 的 dwc2/ci_hdrc 等驱动会自动作为 UDC 设备出现。
# 官网脚本在绑定时直接使用 'UDC' 文件，不需要显式指定 UDC_DEVICE 变量。
# 系统会自动查找可用的 UDC 设备进行绑定。

# 确保脚本以root权限运行
if [ "$(id -u)" -ne 0 ]; then
    echo "This script must be run as root. Please run with 'sudo'."
    exit 1
fi

echo "--------------------------------------"
echo "Configuring USB Gadget for RNDIS ONLY."
echo "--------------------------------------"



# 1. 检查RNDIS所需的内核模块并确保 g_ether 未加载
echo "Checking and ensuring 'g_mass_storage' and 'g_ether' are not loaded, then loading 'libcomposite'..."

# 卸载 g_mass_storage
if lsmod | grep -q g_mass_storage; then
    echo "Unloading g_mass_storage module..."
    modprobe -r g_mass_storage || { echo "WARNING: Failed to unload g_mass_storage. This might cause issues."; }
    sleep 1
fi

# 卸载 g_ether
if lsmod | grep -q g_ether; then
    echo "Unloading g_ether module..."
    modprobe -r g_ether || { echo "WARNING: Failed to unload g_ether. This might cause issues."; }
    sleep 1
fi

# libcomposite 是 gadget 框架的基础
if ! lsmod | grep -q libcomposite; then
    echo "Loading libcomposite module..."
    modprobe libcomposite || { echo "ERROR: Failed to load libcomposite. Exiting."; exit 1; }
fi

# 2. 卸载并清理旧的 gadget 配置 (可选，但推荐在测试时使用以确保干净状态)
if [ -d "${GADGET_ROOT}" ]; then
    echo "Disabling existing gadget '${GADGET_NAME}'..."
    # 尝试解绑当前的 UDC (如果已经绑定)
    if [ -f "${GADGET_ROOT}/UDC" ]; then
        current_udc=$(cat "${GADGET_ROOT}/UDC")
        if [ -n "$current_udc" ]; then
            echo "Unbinding ${current_udc} from previous gadget..."
            echo "" > "${GADGET_ROOT}/UDC" # 解绑 UDC
            sleep 1
        fi
    fi
    rm -rf "${GADGET_ROOT}" # 删除所有旧的配置
    echo "Old gadget configuration removed."
    sleep 1
fi

# 3. 创建新的 gadget 配置
echo "Creating new gadget configuration at ${GADGET_ROOT}..."
mkdir -p "${GADGET_ROOT}"
cd "${GADGET_ROOT}" || { echo "ERROR: Failed to cd to ${GADGET_ROOT}. Exiting."; exit 1; }

# 4. 设置设备描述符 (参考官网脚本的值)
echo "Setting device descriptors..."
#echo 0x0955 > idVendor     # Linux Foundation (官网脚本值)
#echo 0x7020 > idProduct    # Multifunction Composite Gadget (官网脚本中 RNDIS 启用时使用的值)
echo 0x2CA3 > idVendor     # Linux Foundation (官网脚本值)
echo 0xF003 > idProduct    # Multifunction Composite Gadget (官网脚本中 RNDIS 启用时使用的值)
echo 0x0001 > bcdDevice    # v1.0.0
echo 0x0200 > bcdUSB       # USB2

echo 0xEF > bDeviceClass     # Miscellaneous Device Class
echo 0x02 > bDeviceSubClass # Common Class
echo 0x01 > bDeviceProtocol # Interface Association Descriptor (IAD)

# 5. 设置字符串描述符 (参考官网脚本的值)
echo "Setting string descriptors (Manufacturer, Product, Serial)..."
mkdir -p strings/0x409 # English (0x409)

echo "NVIDIA" > strings/0x409/manufacturer
echo "Linux for Tegra" > strings/0x409/product
cat /proc/device-tree/serial-number > strings/0x409/serialnumber

# 6. 创建配置 c.1
echo "Creating configuration 'c.1'..."
cfg="configs/c.1"
mkdir -p "${cfg}/strings/0x409"
echo 0x80 > "${cfg}/bmAttributes" # Self-powered
echo 250 > "${cfg}/MaxPower"     # Max power consumption (250mA)
echo "RNDIS" > "${cfg}/strings/0x409/configuration" # Configuration description

# 7. 配置 RNDIS 功能
echo "Enabling RNDIS function (rndis.usb0)..."
func_rndis="functions/rndis.usb0"
mkdir -p "${func_rndis}"
ln -sf "${func_rndis}" "${cfg}" # Link RNDIS function to configuration c.1

# RNDIS OS Descriptors for Windows auto-detection (参考官网脚本的值)
echo "Setting RNDIS OS Descriptors..."
echo 1 > os_desc/use
echo 0xcd > os_desc/b_vendor_code
echo MSFT100 > os_desc/qw_sign
echo "RNDIS" > "${func_rndis}/os_desc/interface.rndis/compatible_id"
echo "5162001" > "${func_rndis}/os_desc/interface.rndis/sub_compatible_id"
ln -sf "${cfg}" os_desc

# 8. 绑定到 UDC 以激活 Gadget
echo "Activating USB Gadget..."
# 使用 udevadm settle 确保所有设备节点都已创建
udevadm settle -t 5 || :
# 直接将可用的 UDC 设备名称写入 UDC 文件。
# 如果系统有多个 UDC，通常会选择第一个可用的。
# 官网脚本也是直接 'ls /sys/class/udc > UDC' 来完成。
UDC_LIST=$(ls /sys/class/udc)
if [ -z "$UDC_LIST" ]; then
    echo "ERROR: No USB Device Controller (UDC) found in /sys/class/udc/. Cannot activate gadget."
    exit 1
fi
echo "${UDC_LIST%% *}" > UDC # 取第一个 UDC 设备名称
echo "USB Gadget successfully activated on ${UDC_LIST%% *}."

# 9. 配置 RNDIS 网络接口
echo "Configuring RNDIS network interface (usb0)..."

# 等待 usb0 接口出现
echo "Waiting for 'usb0' interface to appear..."
interface_ready=0
for i in $(seq 1 15); do # 等待最多15秒，给系统更多时间
    if ip link show usb0 &> /dev/null; then
        echo "'usb0' interface found."
        interface_ready=1
        break
    fi
    sleep 1
done

if [ "$interface_ready" -eq 0 ]; then
    echo "ERROR: 'usb0' interface did not appear after 15 seconds. RNDIS network configuration failed."
    echo "       Check kernel modules ('libcomposite' and 'usb_f_rndis' which is part of g_ether function) and dmesg for errors."
    exit 1
fi

# 清理旧的桥接设备 (如果存在)
if ip link show pi4br0 &> /dev/null; then
    echo "Removing existing bridge 'pi4br0'..."
    brctl delbr pi4br0
    sleep 1
fi

/sbin/brctl addbr pi4br0 # 创建一个名为 pi4br0 的网络桥接
/sbin/ifconfig pi4br0 "${NET_IP}" netmask "${NET_MASK}" up # 配置桥接接口的IP地址
/sbin/brctl addif pi4br0 usb0 # 将 RNDIS 接口 usb0 添加到桥接
/sbin/ifconfig usb0 up # 确保 usb0 接口被激活

echo "RNDIS network configured to ${NET_IP} on 'pi4br0' (bridging 'usb0')."

echo "--------------------------------------"
echo "USB Gadget RNDIS setup complete."
echo "Connect your device to a PC."
echo "--------------------------------------"

exit 0