OpenTween.Win32Api.RefreshProxySettings C# (CSharp) Method

        private static void RefreshProxySettings(string strProxy)
        {
            const int INTERNET_OPTION_PROXY = 38;
            //const int INTERNET_OPEN_TYPE_PRECONFIG = 0;   //IE setting
            const int INTERNET_OPEN_TYPE_DIRECT = 1;      //Direct
            const int INTERNET_OPEN_TYPE_PROXY = 3;       //Custom

            INTERNET_PROXY_INFO ipi;

            // Filling in structure
            if (!string.IsNullOrEmpty(strProxy))
            {
                ipi.dwAccessType = INTERNET_OPEN_TYPE_PROXY;
                ipi.proxy = Marshal.StringToHGlobalAnsi(strProxy);
                ipi.proxyBypass = Marshal.StringToHGlobalAnsi("local");
            }
            else if (strProxy == null)
            {
                //IE Default
                var p = WebRequest.GetSystemWebProxy();
                if (p.IsBypassed(new Uri("http://www.google.com/")))
                {
                    ipi.dwAccessType = INTERNET_OPEN_TYPE_DIRECT;
                    ipi.proxy = IntPtr.Zero;
                    ipi.proxyBypass = IntPtr.Zero;
                }
                else
                {
                    ipi.dwAccessType = INTERNET_OPEN_TYPE_PROXY;
                    ipi.proxy = Marshal.StringToHGlobalAnsi(p.GetProxy(new Uri("http://www.google.com/")).Authority);
                    ipi.proxyBypass = Marshal.StringToHGlobalAnsi("local");
                }
            }
            else
            {
                ipi.dwAccessType = INTERNET_OPEN_TYPE_DIRECT;
                ipi.proxy = IntPtr.Zero;
                ipi.proxyBypass = IntPtr.Zero;
            }

            try
            {
                // Allocating memory
                var pIpi = Marshal.AllocCoTaskMem(Marshal.SizeOf(ipi));
                if (pIpi.Equals(IntPtr.Zero)) return;
                try
                {
                    // Converting structure to IntPtr
                    Marshal.StructureToPtr(ipi, pIpi, true);
                    var ret = InternetSetOption(IntPtr.Zero,
                                                           INTERNET_OPTION_PROXY,
                                                           pIpi,
                                                           Marshal.SizeOf(ipi));
                }
                finally
                {
                    Marshal.FreeCoTaskMem(pIpi);
                }
            }
            finally
            {
                ipi.Dispose();
            }
        }