[VB/C#] Twitter にログイン

Sub Main()
    ' ログインして Cookie 取得
    Dim cookies = Login("スクリーンネームまたはメールアドレス", "パスワード")

    ' 取得した Cookie を付けてアカウント設定ページにアクセス
    Dim url = "https://twitter.com/settings/account"
    Dim req = WebRequest.CreateHttp(New Uri(url))
    req.CookieContainer = New CookieContainer
    req.CookieContainer.Add(cookies)

    Dim html As String
    Using res = req.GetResponse
        Using rs = res.GetResponseStream
            Using sr = New StreamReader(rs)
                html = sr.ReadToEnd
            End Using
        End Using
    End Using
End Sub

Private Function GetAuthenticityTokenAndCookies() As Tuple(Of String, CookieCollection)
    Dim req = WebRequest.CreateHttp("https://twitter.com/")
    req.Method = "GET"
    req.ServicePoint.Expect100Continue = False
    req.CookieContainer = New CookieContainer

    Using res = DirectCast(req.GetResponse, HttpWebResponse)
        Dim html As String
        Using rs = res.GetResponseStream
            Using sr = New IO.StreamReader(rs, Encoding.UTF8)
                html = sr.ReadToEnd
            End Using
        End Using

        html = html.Substring(html.IndexOf("action=""https://twitter.com/sessions"""))
        Dim m = Regex.Match(html, "value=""(?<token>.*?)""\s+name=""authenticity_token""")

        Return New Tuple(Of String, CookieCollection)(m.Groups("token").Value, res.Cookies)
    End Using
End Function

Private Function Login(name As String, password As String) As CookieCollection
    Dim val = GetAuthenticityTokenAndCookies()
    Dim token = val.Item1
    Dim cookies = val.Item2

    Dim param = String.Format("session%5Busername_or_email%5D={0}&session%5Bpassword%5D={1}&remember_me=0&return_to_ssl=true&scribe_log=&redirect_after_login=%2F&authenticity_token={2}", name, password, token)
    Dim buf = Text.Encoding.ASCII.GetBytes(param)

    Dim uri = New Uri("https://twitter.com/sessions")
    Dim req = WebRequest.CreateHttp(uri)
    req.Method = "POST"
    req.ContentType = "application/x-www-form-urlencoded"
    req.ContentLength = buf.Length
    req.Referer = "https://twitter.com/"
    req.ServicePoint.Expect100Continue = False
    req.CookieContainer = New CookieContainer
    If cookies IsNot Nothing Then
        req.CookieContainer.Add(cookies)
    End If

    Using rs = req.GetRequestStream
        rs.Write(buf, 0, buf.Length)
    End Using

    Dim html As String
    Using res = req.GetResponse
        Using rs = res.GetResponseStream
            Using sr = New StreamReader(rs, Encoding.UTF8)
                html = sr.ReadToEnd
            End Using
        End Using
        Return req.CookieContainer.GetCookies(uri)
    End Using
End Function

static void Main(string[] args)
{
    // ログインして Cookie 取得
    var cookies = Login("スクリーンネームまたはメールアドレス", "パスワード");

    // 取得した Cookie を付けてアカウント設定ページにアクセス
    var url = "https://twitter.com/settings/account";
    var req = WebRequest.CreateHttp(new Uri(url));
    req.CookieContainer = new CookieContainer();
    req.CookieContainer.Add(cookies);

    string html = null;
    using (var res = req.GetResponse())
    {
        using (var rs = res.GetResponseStream())
        {
            using (var sr = new StreamReader(rs))
            {
                html = sr.ReadToEnd();
            }
        }
    }
}

private static Tuple<string, CookieCollection> GetAuthenticityTokenAndCookies()
{
    var req = WebRequest.CreateHttp("https://twitter.com/");
    req.Method = "GET";
    req.ServicePoint.Expect100Continue = false;
    req.CookieContainer = new CookieContainer();

    using (var res = req.GetResponse() as HttpWebResponse)
    {
        string html = null;
        using (var rs = res.GetResponseStream())
        {
            using (var sr = new StreamReader(rs, Encoding.UTF8))
            {
                html = sr.ReadToEnd();
            }
        }

        html = html.Substring(html.IndexOf("action=\"https://twitter.com/sessions\""));
        var m = Regex.Match(html, "value=\"(?<token>.*?)\"\\s+name=\"authenticity_token\"");

        return new Tuple<string, CookieCollection>(m.Groups["token"].Value, res.Cookies);
    }
}

private static CookieCollection Login(string name, string password)
{
    var val = GetAuthenticityTokenAndCookies();
    var token = val.Item1;
    var cookies = val.Item2;

    var param = string.Format("session%5Busername_or_email%5D={0}&session%5Bpassword%5D={1}&remember_me=0&return_to_ssl=true&scribe_log=&redirect_after_login=%2F&authenticity_token={2}", name, password, token);
    var buf = System.Text.Encoding.ASCII.GetBytes(param);

    var uri = new Uri("https://twitter.com/sessions");
    var req = WebRequest.CreateHttp(uri);
    req.Method = "POST";
    req.ContentType = "application/x-www-form-urlencoded";
    req.ContentLength = buf.Length;
    req.Referer = "https://twitter.com/";
    req.ServicePoint.Expect100Continue = false;
    req.CookieContainer = new CookieContainer();
    if (cookies != null)
    {
        req.CookieContainer.Add(cookies);
    }

    using (var rs = req.GetRequestStream())
    {
        rs.Write(buf, 0, buf.Length);
    }

    string html = null;
    using (var res = req.GetResponse())
    {
        using (var rs = res.GetResponseStream())
        {
            using (var sr = new StreamReader(rs, Encoding.UTF8))
            {
                html = sr.ReadToEnd();
            }
        }
        return req.CookieContainer.GetCookies(uri);
    }
}