shadowsocks-windows/shadowsocks-csharp/SystemProxy.cs

using Microsoft.Win32;
using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Text;

namespace shadowsocks_csharp
{
    class SystemProxy
    {

        [DllImport("wininet.dll")]
        public static extern bool InternetSetOption(IntPtr hInternet, int dwOption, IntPtr lpBuffer, int dwBufferLength);
        public const int INTERNET_OPTION_SETTINGS_CHANGED = 39;
        public const int INTERNET_OPTION_REFRESH = 37;
        static bool settingsReturn, refreshReturn;

        public static void UpdateIE()
        {
            // These lines implement the Interface in the beginning of program 
            // They cause the OS to refresh the settings, causing IP to realy update
            settingsReturn = InternetSetOption(IntPtr.Zero, INTERNET_OPTION_SETTINGS_CHANGED, IntPtr.Zero, 0);
            refreshReturn = InternetSetOption(IntPtr.Zero, INTERNET_OPTION_REFRESH, IntPtr.Zero, 0);
        }

        public static void Enable()
        {
            RegistryKey registry = Registry.CurrentUser.OpenSubKey("Software\\Microsoft\\Windows\\CurrentVersion\\Internet Settings", true);
            registry.SetValue("ProxyEnable", 1);
            registry.SetValue("ProxyServer", "127.0.0.1:8123");
            SystemProxy.UpdateIE();
        }

        public static void Disable()
        {
            RegistryKey registry = Registry.CurrentUser.OpenSubKey("Software\\Microsoft\\Windows\\CurrentVersion\\Internet Settings", true);
            registry.SetValue("ProxyEnable", 0);
            registry.SetValue("ProxyServer", "");
            SystemProxy.UpdateIE();
        }
    }
}