C# Proxy Code Console Not Working

Question

I have a problem when converting a VB code to C# code. Here is the code in VB,

<Runtime.InteropServices.DllImport("wininet.dll", SetLastError:=True)> _
    Private Shared Function InternetSetOption(ByVal hInternet As IntPtr, ByVal dwOption As Integer, ByVal lpBuffer As IntPtr, ByVal lpdwBufferLength As Integer) As Boolean
    End Function

    Public Structure Struct_INTERNET_PROXY_INFO
        Public dwAccessType As Integer
        Public proxy As IntPtr
        Public proxyBypass As IntPtr
    End Structure

    Private Sub UseProxy(ByVal strProxy As String)
        Const INTERNET_OPTION_PROXY As Integer = 38
        Const INTERNET_OPEN_TYPE_PROXY As Integer = 3

        Dim struct_IPI As Struct_INTERNET_PROXY_INFO

        struct_IPI.dwAccessType = INTERNET_OPEN_TYPE_PROXY
        struct_IPI.proxy = Marshal.StringToHGlobalAnsi(strProxy)
        struct_IPI.proxyBypass = Marshal.StringToHGlobalAnsi("local")

        Dim intptrStruct As IntPtr = Marshal.AllocCoTaskMem(Marshal.SizeOf(struct_IPI))

        Marshal.StructureToPtr(struct_IPI, intptrStruct, True)

        Dim iReturn As Boolean = InternetSetOption(IntPtr.Zero, INTERNET_OPTION_PROXY, intptrStruct, System.Runtime.InteropServices.Marshal.SizeOf(struct_IPI))
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Label4.Text = (TextBox1.Text & ":" & TextBox2.Text)

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        UseProxy(Label4.Text)
        WebBrowser1.Navigate(TextBox3.Text)
    End Sub

I have tried using some online converters to convert this code and i got the same results. This is the c# code,

[Runtime.InteropServices.DllImport("wininet.dll", SetLastError = true)]
private static bool InternetSetOption(IntPtr hInternet, int dwOption, IntPtr lpBuffer, int lpdwBufferLength)
{
}

public struct Struct_INTERNET_PROXY_INFO
{
    public int dwAccessType;
    public IntPtr proxy;
    public IntPtr proxyBypass;
}

private void UseProxy(string strProxy)
{
    const int INTERNET_OPTION_PROXY = 38;
    const int INTERNET_OPEN_TYPE_PROXY = 3;

    Struct_INTERNET_PROXY_INFO struct_IPI = default(Struct_INTERNET_PROXY_INFO);

    struct_IPI.dwAccessType = INTERNET_OPEN_TYPE_PROXY;
    struct_IPI.proxy = Marshal.StringToHGlobalAnsi(strProxy);
    struct_IPI.proxyBypass = Marshal.StringToHGlobalAnsi("local");

    IntPtr intptrStruct = Marshal.AllocCoTaskMem(Marshal.SizeOf(struct_IPI));

    Marshal.StructureToPtr(struct_IPI, intptrStruct, true);

    bool iReturn = InternetSetOption(IntPtr.Zero, INTERNET_OPTION_PROXY, intptrStruct, System.Runtime.InteropServices.Marshal.SizeOf(struct_IPI));
}

private void Button1_Click(System.Object sender, System.EventArgs e)
{
    Label4.Text = (TextBox1.Text + ":" + TextBox2.Text);

}

private void Button2_Click(System.Object sender, System.EventArgs e)
{
    UseProxy(Label4.Text);
    WebBrowser1.Navigate(TextBox3.Text);
}

I am using VS 12 and in a windows form application the code gives me a error saying,

Error 2 'WindowsFormsApplication1.Form1.InternetSetOption(System.IntPtr, int, System.IntPtr, int)': not all code paths return a value

Error 1 The type or namespace name 'Runtime' could not be found (are you missing a using directive or an assembly reference?)

I have tried using System.Runtime, using System.Runtime.InteropServices and System.Runtime.InteropServices.WindowsRuntime but no use.

I have a console application which sends httpwebrequest and do some work. So I somehow need the program to use proxy when connecting. So when the program starts, it will also start the proxy and all the requests the program send will be using proxy.

I also want the proxy to just affect the program and not all the computer as I want the user to be able to browse the computer freely.

--Edit-- I have got a solution for above. Now this is the problem. Now this code doesn't seem to work with console app. I used

static void Main()
        {
            Console.WriteLine("Ip before Proxy /r/n");
            HTTPGet req = new HTTPGet();
            req.Request("http://checkip.dyndns.org");
            string[] a = req.ResponseBody.Split(':');
            string a2 = a[1].Substring(1);
            string[] a3 = a2.Split('<');
            string a4 = a3[0];
            Console.WriteLine(a4);

            UseProxy("219.93.183.106:8080");
            Console.WriteLine("Ip after Proxy /r/n");
            HTTPGet req1 = new HTTPGet();
            req1.Request("http://checkip.dyndns.org");
            string[] a1 = req1.ResponseBody.Split(':');
            string a21 = a1[1].Substring(1);
            string[] a31 = a21.Split('<');
            string a41 = a31[0];
            Console.WriteLine(a41);
            Console.ReadLine();
        }

I get both the results as my IP. The HTTPGet is a class from this question in stack overflow : c# - Get public/external IP address?

Any help on how to use it on console ? or am I doing something wrong ?

score 1 · Answer 1 · edited May 23 '17 at 10:26

1

Looks like you are trying to do this: How do I use InternetSetOption?

Note the definition of interop:

[DllImport("wininet.dll", SetLastError = true)]
private static extern bool InternetSetOption(
    IntPtr hInternet,
    int dwOption,
    IntPtr lpBuffer,
    int lpdwBufferLength);

edited May 23 '17 at 10:26

Community

1
1

answered Apr 06 '14 at 07:52

Tedd Hansen

12,074
14
61
97

**Thank you Very Much**. Will my code also work with console application ? – user3502927 Apr 06 '14 at 08:33
This code doesn't works with a console app. There are no errors. I have edited my question. please check it and i would really thank you if you can solve it – user3502927 Apr 06 '14 at 10:03

score 0 · Answer 2 · answered Apr 06 '14 at 07:54

0

[DllImport("wininet.dll", SetLastError = true)]
 private static extern bool InternetSetOption(IntPtr hInternet, int dwOption, IntPtr lpBuffer, int lpdwBufferLength);

And add a using to System.Runtime.InteropServices

answered Apr 06 '14 at 07:54

Ryan Newington

199
2
8

score 0 · Accepted Answer · answered Apr 06 '14 at 08:59

You can just remove { } from the internetsetoption and add ; at end. The code will look like,

 [DllImport("wininet.dll", SetLastError = true)]
    private static extern bool InternetSetOption(
        IntPtr hInternet,
        int dwOption,
        IntPtr lpBuffer,
        int lpdwBufferLength);


    public struct Struct_INTERNET_PROXY_INFO
    {
        public int dwAccessType;
        public IntPtr proxy;
        public IntPtr proxyBypass;
    }

    private void UseProxy(string strProxy)
    {
        const int INTERNET_OPTION_PROXY = 38;
        const int INTERNET_OPEN_TYPE_PROXY = 3;

        Struct_INTERNET_PROXY_INFO struct_IPI = default(Struct_INTERNET_PROXY_INFO);

        struct_IPI.dwAccessType = INTERNET_OPEN_TYPE_PROXY;
        struct_IPI.proxy = Marshal.StringToHGlobalAnsi(strProxy);
        struct_IPI.proxyBypass = Marshal.StringToHGlobalAnsi("local");

        IntPtr intptrStruct = Marshal.AllocCoTaskMem(Marshal.SizeOf(struct_IPI));

        Marshal.StructureToPtr(struct_IPI, intptrStruct, true);

        bool iReturn = InternetSetOption(IntPtr.Zero, INTERNET_OPTION_PROXY, intptrStruct, System.Runtime.InteropServices.Marshal.SizeOf(struct_IPI));
    }

    private void Button1_Click(System.Object sender, System.EventArgs e)
    {
        Label4.Text = (TextBox1.Text + ":" + TextBox2.Text);

    }

    private void Button2_Click(System.Object sender, System.EventArgs e)
    {
        UseProxy(Label4.Text);
        WebBrowser1.Navigate(TextBox3.Text);
    }

and I guess you already have set references to system.runtime and system.runtime.interopservices

I have tested this code with two buttons, one label and webbrowser as in code and they work fine with some free proxies from hidemyass.com.

C# Proxy Code Console Not Working

3 Answers3