Probe.cs

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;

static class N {
    public const int DIGCF_PRESENT = 0x02;
    public const int DIGCF_DEVICEINTERFACE = 0x10;
    public const uint GENERIC_READ = 0x80000000;
    public const uint FILE_SHARE_READ = 1, FILE_SHARE_WRITE = 2;
    public const uint OPEN_EXISTING = 3;
    public static readonly IntPtr INVALID = new IntPtr(-1);

    [StructLayout(LayoutKind.Sequential)]
    public struct SP_DEVICE_INTERFACE_DATA {
        public int cbSize; public Guid InterfaceClassGuid; public int Flags; public IntPtr Reserved;
    }
    [StructLayout(LayoutKind.Sequential)]
    public struct HIDD_ATTRIBUTES {
        public int Size; public ushort VendorID; public ushort ProductID; public ushort VersionNumber;
    }
    [StructLayout(LayoutKind.Sequential)]
    public struct HIDP_CAPS {
        public ushort Usage, UsagePage, InputReportByteLength, OutputReportByteLength, FeatureReportByteLength;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 17)] public ushort[] Reserved;
        public ushort NumberLinkCollectionNodes, NumberInputButtonCaps, NumberInputValueCaps, NumberInputDataIndices,
                      NumberOutputButtonCaps, NumberOutputValueCaps, NumberOutputDataIndices,
                      NumberFeatureButtonCaps, NumberFeatureValueCaps, NumberFeatureDataIndices;
    }

    [DllImport("hid.dll")] public static extern void HidD_GetHidGuid(out Guid g);
    [DllImport("hid.dll")] public static extern bool HidD_GetAttributes(IntPtr h, ref HIDD_ATTRIBUTES a);
    [DllImport("hid.dll")] public static extern bool HidD_GetPreparsedData(IntPtr h, out IntPtr pp);
    [DllImport("hid.dll")] public static extern bool HidD_FreePreparsedData(IntPtr pp);
    [DllImport("hid.dll")] public static extern int  HidP_GetCaps(IntPtr pp, ref HIDP_CAPS caps);
    [DllImport("hid.dll", CharSet = CharSet.Unicode)] public static extern bool HidD_GetProductString(IntPtr h, StringBuilder sb, int len);

    [DllImport("setupapi.dll", CharSet = CharSet.Unicode)]
    public static extern IntPtr SetupDiGetClassDevs(ref Guid g, IntPtr en, IntPtr hwnd, int flags);
    [DllImport("setupapi.dll")]
    public static extern bool SetupDiEnumDeviceInterfaces(IntPtr s, IntPtr di, ref Guid g, int i, ref SP_DEVICE_INTERFACE_DATA d);
    [DllImport("setupapi.dll", CharSet = CharSet.Unicode)]
    public static extern bool SetupDiGetDeviceInterfaceDetail(IntPtr s, ref SP_DEVICE_INTERFACE_DATA d, IntPtr det, int size, ref int req, IntPtr dd);
    [DllImport("setupapi.dll")] public static extern bool SetupDiDestroyDeviceInfoList(IntPtr s);

    [DllImport("kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
    public static extern IntPtr CreateFile(string p, uint acc, uint share, IntPtr sa, uint disp, uint flags, IntPtr tmpl);
    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern bool ReadFile(IntPtr h, byte[] buf, int n, out int read, IntPtr ov);
    [DllImport("kernel32.dll")] public static extern bool CloseHandle(IntPtr h);
}

class Dev {
    public string Path, Product;
    public ushort Vid, Pid, UsagePage, Usage, InLen;
}

class Probe {
    static List<Dev> Enumerate() {
        var list = new List<Dev>();
        Guid g; N.HidD_GetHidGuid(out g);
        IntPtr set = N.SetupDiGetClassDevs(ref g, IntPtr.Zero, IntPtr.Zero, N.DIGCF_PRESENT | N.DIGCF_DEVICEINTERFACE);
        if (set == N.INVALID) return list;
        var did = new N.SP_DEVICE_INTERFACE_DATA();
        did.cbSize = Marshal.SizeOf(typeof(N.SP_DEVICE_INTERFACE_DATA));
        for (int i = 0; N.SetupDiEnumDeviceInterfaces(set, IntPtr.Zero, ref g, i, ref did); i++) {
            int req = 0;
            N.SetupDiGetDeviceInterfaceDetail(set, ref did, IntPtr.Zero, 0, ref req, IntPtr.Zero);
            if (req <= 0) continue;
            IntPtr buf = Marshal.AllocHGlobal(req);
            try {
                Marshal.WriteInt32(buf, IntPtr.Size == 8 ? 8 : 6);
                if (!N.SetupDiGetDeviceInterfaceDetail(set, ref did, buf, req, ref req, IntPtr.Zero)) continue;
                string path = Marshal.PtrToStringUni(new IntPtr(buf.ToInt64() + 4));
                IntPtr h = N.CreateFile(path, 0, N.FILE_SHARE_READ | N.FILE_SHARE_WRITE, IntPtr.Zero, N.OPEN_EXISTING, 0, IntPtr.Zero);
                if (h == N.INVALID) continue;
                try {
                    var at = new N.HIDD_ATTRIBUTES(); at.Size = Marshal.SizeOf(typeof(N.HIDD_ATTRIBUTES));
                    if (!N.HidD_GetAttributes(h, ref at)) continue;
                    IntPtr pp;
                    if (!N.HidD_GetPreparsedData(h, out pp)) continue;
                    var caps = new N.HIDP_CAPS();
                    N.HidP_GetCaps(pp, ref caps);
                    N.HidD_FreePreparsedData(pp);
                    var sb = new StringBuilder(256);
                    string prod = N.HidD_GetProductString(h, sb, 256) ? sb.ToString() : "";
                    list.Add(new Dev { Path = path, Product = prod, Vid = at.VendorID, Pid = at.ProductID,
                                       UsagePage = caps.UsagePage, Usage = caps.Usage, InLen = caps.InputReportByteLength });
                } finally { N.CloseHandle(h); }
            } finally { Marshal.FreeHGlobal(buf); }
        }
        N.SetupDiDestroyDeviceInfoList(set);
        return list;
    }

    static string Hex(byte[] b, int n) {
        var sb = new StringBuilder();
        for (int i = 0; i < n; i++) sb.Append(b[i].ToString("X2")).Append(' ');
        return sb.ToString().TrimEnd();
    }

    static void Main(string[] args) {
        bool listOnly = args.Length > 0 && args[0] == "list";
        var all = Enumerate();

        Console.WriteLine("=== HID collections for Apple (VID 0x004C) ===");
        var apple = new List<Dev>();
        foreach (var d in all) {
            if (d.Vid != 0x004C) continue;
            apple.Add(d);
            Console.WriteLine(string.Format(
                "  [{0}] PID=0x{1:X4} UsagePage=0x{2:X2} Usage=0x{3:X2} InputReportLen={4} Product=\"{5}\"",
                apple.Count - 1, d.Pid, d.UsagePage, d.Usage, d.InLen, d.Product));
            Console.WriteLine("        " + d.Path);
        }
        if (apple.Count == 0) {
            Console.WriteLine("  none found - is the keyboard connected right now?");
            return;
        }
        if (listOnly) return;

        Console.WriteLine();
        Console.WriteLine("=== Listening. Press F10, F11, F12 (a few times each), then Ctrl+C ===");
        Console.WriteLine();

        int opened = 0;
        foreach (var d in apple) {
            if (d.UsagePage == 0x01 && d.Usage == 0x06) continue; // plain keyboard collection: owned by Windows
            var dd = d;
            var t = new Thread(delegate() {
                IntPtr h = N.CreateFile(dd.Path, N.GENERIC_READ, N.FILE_SHARE_READ | N.FILE_SHARE_WRITE,
                                        IntPtr.Zero, N.OPEN_EXISTING, 0, IntPtr.Zero);
                if (h == N.INVALID) {
                    Console.WriteLine(string.Format("  ! cannot open UsagePage=0x{0:X2} Usage=0x{1:X2} (win32 err {2})",
                        dd.UsagePage, dd.Usage, Marshal.GetLastWin32Error()));
                    return;
                }
                Console.WriteLine(string.Format("  + reading UsagePage=0x{0:X2} Usage=0x{1:X2}", dd.UsagePage, dd.Usage));
                int len = dd.InLen > 0 ? dd.InLen : 64;
                var buf = new byte[len];
                while (true) {
                    int read;
                    if (!N.ReadFile(h, buf, len, out read, IntPtr.Zero)) break;
                    if (read <= 0) continue;
                    Console.WriteLine(string.Format("UP=0x{0:X2} U=0x{1:X2}  |  {2}", dd.UsagePage, dd.Usage, Hex(buf, read)));
                }
                N.CloseHandle(h);
            });
            t.IsBackground = true;
            t.Start();
            opened++;
        }
        if (opened == 0) { Console.WriteLine("  no non-keyboard collections to read."); return; }
        Thread.Sleep(Timeout.Infinite);
    }
}