How To Modify 2 Parts Of A String Inside A Variable From A TextBox Input OR another variable (Visual-CodePudding

I'm trying to get my first VB Program running, i am attempting to run a HTTP POST request, i have it funcional when i hardcode my account details but would like to use the text box as username & password inputs, Im learning as i go and any input for optimisations & improvements are welcome, i plan to add internet check (ping or similar) & only attempt login when offline but its a WIP, More info on what im trying to acheive is here https://github.com/aidanmacgregor/BTWi-fi_Autologin-Shell_Script-MACRODROID-WISPr-HTTP_POST-HTTP_GET-OpenWRT

i need to edit the [email protected] and PASSWORD parts but leave the username= and &password=

Dim postData As String = "[email protected]&password=PASSWORD"

Full Code For Refrence

Imports System.Net
Imports System.Text
Imports System.IO

Public Class Form1

    Dim logincookie As CookieContainer
    Dim postEmail As String = txtEmail.Text
    Dim postPassword As String = txtPassword.Text
    Dim postData As String = "[email protected]&password=PASSWORD"

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Dim comboSource As New Dictionary(Of String, String)()
        comboSource.Add("1", "BT Home Broadband")
        comboSource.Add("2", "BT Buisness Broadband")
        comboSource.Add("3", "BT Wi-Fi")
        comboAcctype.DataSource = New BindingSource(comboSource, Nothing)
        comboAcctype.DisplayMember = "Value"
        comboAcctype.ValueMember = "Key"

    End Sub



    Private Sub butStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butStart.Click
        Dim keyAcctype As String = DirectCast(comboAcctype.SelectedItem, KeyValuePair(Of String, String)).Key
        Dim valueAcctype As String = DirectCast(comboAcctype.SelectedItem, KeyValuePair(Of String, String)).Value

        Dim tempCookies As New CookieContainer
        Dim encoding As New UTF8Encoding
        Dim byteData As Byte() = encoding.GetBytes(postData)


        If keyAcctype = 1 Then

            Dim postReq As HttpWebRequest = DirectCast(WebRequest.Create("https://btwifi.com:8443/tbbLogon"), HttpWebRequest)
            postReq.Method = "POST"
            postReq.KeepAlive = False
            postReq.CookieContainer = tempCookies
            postReq.ContentType = "application/x-www-form-urlencoded"
            postReq.Referer = "https://google.com"
            postReq.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; RV:26.0) Gecko/20100101 Firefox/26.0"
            postReq.ContentLength = byteData.Length

            Dim postreqstream As Stream = postReq.GetRequestStream()
            postreqstream.Write(byteData, 0, byteData.Length)
            postreqstream.Close()
            Dim postresponse As HttpWebResponse

            postresponse = DirectCast(postReq.GetResponse(), HttpWebResponse)
            tempCookies.Add(postresponse.Cookies)
            logincookie = tempCookies

            Dim postreqreader As New StreamReader(postresponse.GetResponseStream())
            Dim thepage As String = postreqreader.ReadToEnd
            RichTextBox1.Text = thepage

        ElseIf keyAcctype = 2 Then

            Dim postReq As HttpWebRequest = DirectCast(WebRequest.Create("https://www.btwifi.com:8443/ante?partnerNetwork=btb"), HttpWebRequest)
            postReq.Method = "POST"
            postReq.KeepAlive = False
            postReq.CookieContainer = tempCookies
            postReq.ContentType = "application/x-www-form-urlencoded"
            postReq.Referer = "https://google.com"
            postReq.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; RV:26.0) Gecko/20100101 Firefox/26.0"
            postReq.ContentLength = byteData.Length

            Dim postreqstream As Stream = postReq.GetRequestStream()
            postreqstream.Write(byteData, 0, byteData.Length)
            postreqstream.Close()
            Dim postresponse As HttpWebResponse

            postresponse = DirectCast(postReq.GetResponse(), HttpWebResponse)
            tempCookies.Add(postresponse.Cookies)
            logincookie = tempCookies

            Dim postreqreader As New StreamReader(postresponse.GetResponseStream())
            Dim thepage As String = postreqreader.ReadToEnd
            RichTextBox1.Text = thepage

        ElseIf keyAcctype = 3 Then

            Dim postReq As HttpWebRequest = DirectCast(WebRequest.Create("https://www.btwifi.com:8443/ante"), HttpWebRequest)
            postReq.Method = "POST"
            postReq.KeepAlive = False
            postReq.CookieContainer = tempCookies
            postReq.ContentType = "application/x-www-form-urlencoded"
            postReq.Referer = "https://google.com"
            postReq.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; RV:26.0) Gecko/20100101 Firefox/26.0"
            postReq.ContentLength = byteData.Length

            Dim postreqstream As Stream = postReq.GetRequestStream()
            postreqstream.Write(byteData, 0, byteData.Length)
            postreqstream.Close()
            Dim postresponse As HttpWebResponse

            postresponse = DirectCast(postReq.GetResponse(), HttpWebResponse)
            tempCookies.Add(postresponse.Cookies)
            logincookie = tempCookies

            Dim postreqreader As New StreamReader(postresponse.GetResponseStream())
            Dim thepage As String = postreqreader.ReadToEnd
            RichTextBox1.Text = thepage

        End If

    End Sub



    Private Sub butStop_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butStop.Click

        Dim postData As String = ""
        Dim tempCookies As New CookieContainer
        Dim encoding As New UTF8Encoding
        Dim byteData As Byte() = encoding.GetBytes(postData)

        Dim postReq As HttpWebRequest = DirectCast(WebRequest.Create("https://btwifi.com:8443/accountLogoff/home?confirmed=true"), HttpWebRequest)
        postReq.Method = "POST"
        postReq.KeepAlive = False
        postReq.CookieContainer = tempCookies
        postReq.ContentType = "application/x-www-form-urlencoded"
        postReq.Referer = "https://google.com"
        postReq.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; RV:26.0) Gecko/20100101 Firefox/26.0"
        postReq.ContentLength = byteData.Length

        Dim postreqstream As Stream = postReq.GetRequestStream()
        postreqstream.Write(byteData, 0, byteData.Length)
        postreqstream.Close()
        Dim postresponse As HttpWebResponse

        postresponse = DirectCast(postReq.GetResponse(), HttpWebResponse)
        tempCookies.Add(postresponse.Cookies)
        logincookie = tempCookies
        Dim postreqreader As New StreamReader(postresponse.GetResponseStream())

        Dim thepage As String = postreqreader.ReadToEnd

        RichTextBox1.Text = thepage

    End Sub



End Class

CodePudding user response：

Ok, so I'm still not 100% sure we've got the full picture here, espically after the Null object reference exception you've mentioned and would still be very helpful if you actually updated you question with the relevant details. Including the solution you've posted in the comments, you've got some options. I'm writing this answer because I don't feel continuing to offer advice via the comments is going to achieve anything more.

Option 1 - Using the "$" string Interpolation operator (However that is spelt)

 Dim postData As String = $"username={txtEmail.Text}&password={txtPassword.Text}"

Option 2 - Using the String.Format Function

 Dim postData as String = String.Format("username={0}&password={1}",txtEmail.Text, txtPassword.Text)

Option 3 - Basic String concatenation

 Dim postData As String = "username=" & txtEmail.Text & "&password=" & txtPassword.Text

Assuming no other underlying issues any one of these options (There are plenty more btw) will provide the required credential string