c# - Login to instagram programmatically

Question

I am trying to log in to instagram using web requests. I am having a bad time understanding what's going on. Getting this: The remote server returned an error: (403) Forbidden. What I have so far:

    public static string csrf;
    CookieContainer c1 = new CookieContainer();

    private void button1_Click(object sender, EventArgs e)
    {
        string PostData = String.Format("csrfmiddlewaretoken={0}&username=ra123&password=ra12345678",getToken());

        HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create("https://instagram.com/accounts/login/");
        req.Method = "POST";
        req.ContentType = "application/x-www-form-urlencoded";
        req.KeepAlive = true;
        req.AllowAutoRedirect = true;              
        req.CookieContainer = c1;
        byte[] byteArray = Encoding.ASCII.GetBytes(PostData);
        req.ContentLength = byteArray.Length;
        Stream dataStream = req.GetRequestStream();
        dataStream.Write(byteArray, 0, byteArray.Length);
        dataStream.Flush();
        dataStream.Close();

            HttpWebResponse webResp = (HttpWebResponse)req.GetResponse();
            Stream datastream = webResp.GetResponseStream();
            StreamReader reader = new StreamReader(datastream);
            string s = reader.ReadToEnd();
            MessageBox.Show(s);
            if (s.Contains("ra123"))
            {

                MessageBox.Show("Loggedin");

            }
            else
            {
                MessageBox.Show("Not");
            }

    }


    string getToken()
    {
        string p = "<input type="hidden" name="csrfmiddlewaretoken" value="(.*)"/>";
        HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create("https://instagram.com/accounts/login/");
        req.Method = "GET";
        req.CookieContainer = c1;

        HttpWebResponse resp = (HttpWebResponse)req.GetResponse();
        Stream data = resp.GetResponseStream();
        StreamReader sr = new StreamReader(data);
        string src = sr.ReadToEnd();

        Match m = Regex.Match(src, p);
        if (m.Success)
        {
           return (m.Groups[1].Value.ToString());
        }
        return false.ToString();
    }

Answer 1

The problem with the login is that the request needs to set the cookie at the header, and the container is not setting it since is changes at every login when you access from an unknown explorer. Here is what you can do:

WebResponse Response; 
HttpWebRequest Request;
Uri url = new Uri("http://thewebpage.com:port/login/");

CookieContainer cookieContainer = new CookieContainer();

Request = (HttpWebRequest)WebRequest.Create(url);
Request.Method = "GET";
Request.CookieContainer = cookieContainer;

// Get the first response to obtain the cookie where you will find the "csrfmiddlewaretoken" value
Response = Request.GetResponse(); 

string Parametros = "csrfmiddlewaretoken=" + cookieContainer.GetCookies(url)["csrftoken"].Value + "&username=USER&password=PASSWORD&next="; // This whill set the correct url to access

Request = (HttpWebRequest)WebRequest.Create(url); // it is important to use the same url used for the first request
Request.Method = "POST";
Request.ContentType = "application/x-www-form-urlencoded";
Request.UserAgent = "Other";
// Place the cookie container to obtain the new cookies for further access
Request.CookieContainer = cookieContainer;
Request.Headers.Add("Cookie",Response.Headers.Get("Set-Cookie")); // This is the most important step, you have to place the cookies at the header (without this line you will get the 403 Forbidden exception                                                   

byte[] byteArray = Encoding.UTF8.GetBytes(Parametros);
Request.ContentLength = byteArray.Length;

Stream dataStream = Request.GetRequestStream();
dataStream.Responseite(byteArray, 0, byteArray.Length);
dataStream.Close();

Response = Request.GetResponse();