ScanBluetoothPorts

ScanBluetoothPorts.cs

using System;
using System.Runtime.InteropServices;
using System.Text;
using Microsoft.Win32;
using Microsoft.Win32.SafeHandles;

namespace ConsoleApp2
{
    class Program
    {
        static void Main(string[] args)
        {
            ScanBluetoothPorts();
        }

        static void ScanBluetoothPorts()
        {
            var p = new BLUETOOTH_DEVICE_SEARCH_PARAMS()
            {
                fReturnAuthenticated = true,
                fReturnConnected = true,
                fReturnUnknown = true,
                fReturnRemembered = true,
                dwSize = Marshal.SizeOf<BLUETOOTH_DEVICE_SEARCH_PARAMS>(),
                cTimeoutMultiplier = 10
            };

            var info = new BLUETOOTH_DEVICE_INFO()
            {
                dwSize = Marshal.SizeOf<BLUETOOTH_DEVICE_INFO>()
            };

            int i = 0;
            var ptr = BluetoothFindFirstDevice(ref p, ref info);
            while (ptr != IntPtr.Zero)
            {
                Console.WriteLine(GetLocalServicePortName(i) + " -> " + info.szName);

                info = new BLUETOOTH_DEVICE_INFO();
                if (!BluetoothFindNextDevice(ptr, ref info))
                {
                    BluetoothFindDeviceClose(ptr);
                    break;
                }

                i++;
            }
        }

        static string GetLocalServicePortName(int index)
        {
            using (var key = Registry.LocalMachine.OpenSubKey(@"SYSTEM\CurrentControlSet\Services\BTHPORT\Parameters\LocalServices\" + SerialPortServiceClass_UUID.ToString("B") + @"\" + index, false))
            {
                int instanceId = (int)key.GetValue("PnpInstance");
                var sb = new StringBuilder(256);
                ulong address = 0;
                int err = BluetoothGetServicePnpInstance(ref address, SerialPortServiceClass_UUID, instanceId, sb, sb.Capacity, out IntPtr instanceKey);
                if (err == 0)
                {
                    using (var rk = RegistryKey.FromHandle(new SafeRegistryHandle(instanceKey, true)))
                    {
                        return rk.GetValue("PortName") as string;
                    }
                }
            }
            return null;
        }

        // officially undocumented, but check https://download.microsoft.com/download/9/3/5/935520EC-D9E2-413E-BEA7-0B865A79B18C/Basics%20of%20Secure%20Design%20Development%20Test.ppsx
        // slide #62
        [DllImport("BluetoothApis.dll", SetLastError = true)]
        private static extern int BluetoothGetServicePnpInstance(ref ulong pDeviceAddress, [MarshalAs(UnmanagedType.LPStruct)] Guid ServiceGuid, int InstanceId, [MarshalAs(UnmanagedType.LPWStr)] StringBuilder buffer, int BufferSize, out IntPtr phKey);

        [DllImport("BluetoothApis.dll", SetLastError = true)]
        private static extern IntPtr BluetoothFindFirstDevice(ref BLUETOOTH_DEVICE_SEARCH_PARAMS pbtsp, ref BLUETOOTH_DEVICE_INFO pbtdi);

        [DllImport("BluetoothApis.dll", SetLastError = true)]
        private static extern bool BluetoothFindNextDevice(IntPtr hFind, ref BLUETOOTH_DEVICE_INFO pbtdi);

        [DllImport("BluetoothApis.dll", SetLastError = true)]
        private static extern bool BluetoothFindDeviceClose(IntPtr hFind);

        private static readonly Guid SerialPortServiceClass_UUID = new Guid("00001101-0000-1000-8000-00805F9B34FB");
        private const int BLUETOOTH_MAX_NAME_SIZE = 248;

        [StructLayout(LayoutKind.Sequential)]
        private struct BLUETOOTH_DEVICE_SEARCH_PARAMS
        {
            public int dwSize;
            public bool fReturnAuthenticated;
            public bool fReturnRemembered;
            public bool fReturnUnknown;
            public bool fReturnConnected;
            public bool fIssueInquiry;
            public byte cTimeoutMultiplier;
            public IntPtr hRadio;
        }

        [StructLayout(LayoutKind.Sequential)]
        private struct SYSTEMTIME
        {
            [MarshalAs(UnmanagedType.U2)]
            public short Year;
            [MarshalAs(UnmanagedType.U2)]
            public short Month;
            [MarshalAs(UnmanagedType.U2)]
            public short DayOfWeek;
            [MarshalAs(UnmanagedType.U2)]
            public short Day;
            [MarshalAs(UnmanagedType.U2)]
            public short Hour;
            [MarshalAs(UnmanagedType.U2)]
            public short Minute;
            [MarshalAs(UnmanagedType.U2)]
            public short Second;
            [MarshalAs(UnmanagedType.U2)]
            public short Milliseconds;
        }

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
        private struct BLUETOOTH_DEVICE_INFO
        {
            public int dwSize;
            public ulong Address;
            public int ulClassofDevice;
            public bool fConnected;
            public bool fRemembered;
            public bool fAuthenticated;
            public SYSTEMTIME stLastSeen;
            public SYSTEMTIME stLastUsed;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = BLUETOOTH_MAX_NAME_SIZE)]
            public string szName;
        }
    }
}