A simple HTTPListener to enable muting remotely

HTTPMuter.cs

using System;
using System.Net;
using System.Runtime.InteropServices;
using System.Text;

class Program
{
    static readonly HttpListener httpListener = new HttpListener();

    static void Main(string[] args)
    {
        httpListener.Prefixes.Add("http://*:9000/");
        httpListener.Start();
        Console.WriteLine("Listening, press any key to exit.");
        httpListener.BeginGetContext(GetContextCallback, null);
        Console.ReadKey();
        httpListener.Stop();
    }

    public static void GetContextCallback(IAsyncResult result)
    {
        var context = httpListener.EndGetContext(result);
        var path = context.Request.Url.LocalPath;

        if (path.StartsWith("/mute"))
            Marshal.ThrowExceptionForHR(GetMaster().SetMute(true, Guid.Empty));
        else if (path.StartsWith("/unmute"))
            Marshal.ThrowExceptionForHR(GetMaster().SetMute(false, Guid.Empty));

        var buffer = Encoding.UTF8.GetBytes(path);
        context.Response.ContentLength64 = buffer.Length;
        using (var outputStream = context.Response.OutputStream)
            outputStream.Write(buffer, 0, buffer.Length);

        httpListener.BeginGetContext(GetContextCallback, null);
    }

    private static IAudioEndpointVolume GetMaster()
    {
        var deviceEnum = (IMMDeviceEnumerator)(new MMDeviceEnumerator());
        IMMDevice defaultDevice;
        Marshal.ThrowExceptionForHR(deviceEnum.GetDefaultAudioEndpoint(0, 1, out defaultDevice));

        IAudioEndpointVolume result;
        var aevID = typeof(IAudioEndpointVolume).GUID;
        Marshal.ThrowExceptionForHR(defaultDevice.Activate(ref aevID, 23, 0, out result));
        return result;
    }

    [ComImport, Guid("BCDE0395-E52F-467C-8E3D-C4579291692E")]
    class MMDeviceEnumerator { }

    [Guid("A95664D2-9614-4F35-A746-DE8DB63617E6"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    internal interface IMMDeviceEnumerator
    {
        int f(); // You have to have this, don't ask questions.
        int GetDefaultAudioEndpoint(int dataFlow, int role, out IMMDevice endpoint);
    }

    [Guid("D666063F-1587-4E43-81F1-B948E807363F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    internal interface IMMDevice
    {
        int Activate(ref Guid id, int clsCtx, int activationParams, out IAudioEndpointVolume pointer);
    }

    [Guid("5CDF2C82-841E-4546-9722-0CF74078229A"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    internal interface IAudioEndpointVolume
    {
        int f(); int g(); int h(); int i(); int j(); int k(); int l(); int m(); int n();
        int SetMasterVolumeLevelScalar(float fLevel, Guid pguidEventContext);
        int GetMasterVolumeLevelScalar(out float pfLevel);
        int SetMute([MarshalAs(UnmanagedType.Bool)] Boolean bMute, Guid pguidEventContext);
        int GetMute(out bool pbMute);
    }
}