[RESOLVED] UPNP Port Forwarding Help (Error appeared out of nowhere)

[stepdragon]

I'm working on a type of p2p program, and I found the need to forward ports. That can get complicated for the average user, so I'm including the option to use UPNP to forward the ports for them. I'm using code I found HERE, and it worked too! then randomly it stopped working. I don't remember changing anything in the code, yet now I'm getting an error. Any help would be appreciated.


This is the entire code. I have the Exception Highlighted in Red. The project includes a Listview (6 columns), three buttons (4, 5, 6), a progress bar, and a background worker.

Imports System.Net.Sockets

Public Class Form1

    Dim upnpnat As New NATUPNPLib.UPnPNATClass()
    Dim mappings As NATUPNPLib.IStaticPortMappingCollection = upnpnat.StaticPortMappingCollection

    Dim items2display() As ListViewItem

    Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        BackgroundWorker2.CancelAsync()
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        Dim addstring = InputBox("Enter the External Port, The Protocol, The Internal Port, The IP Address to forward to, and The Description of the connection. Seperate them each by commas, no spaces (except in the description)", "Add Port Forward", "80,TCP,80,192.168.1.1,Default Addition")

        Dim parts() As String = addstring.Split(CChar(","))

        Dim Port1 As Integer = Integer.Parse(parts(0))
        Dim Port2 As Integer = Integer.Parse(parts(2))

        mappings.Add(Port1, parts(1), Port2, parts(3), True, parts(4))
    End Sub

    Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        ProgressBar1.Maximum = mappings.Count 'Throws 'Object reference not set to an instance of an object.'

        Dim i = 0

        If ListView1.Items.Count > 0 Then
            For i = 1 To ListView1.Items.Count
                ListView1.Items.RemoveAt(0)
            Next
        End If

        ReDim items2display(mappings.Count)

        BackgroundWorker2.RunWorkerAsync()
    End Sub

    Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
        If ListView1.SelectedItems.Count = 0 Then
            Dim port As Integer = Integer.Parse(ListView1.SelectedItems.Item(0).SubItems.Item(3).Text)
            Dim Protocol As String = ListView1.SelectedItems.Item(0).SubItems.Item(1).Text

            mappings.Remove(port, Protocol)
        Else
            MsgBox("select the one to remove, (trust me, only remove a test one)")
        End If
    End Sub

    Private Sub BackgroundWorker2_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker2.DoWork
        Dim i = 0

        ' do something with the port mapping, such as displaying it in a listbox
        For Each portMapping As NATUPNPLib.IStaticPortMapping In mappings

            Dim thisitem As New ListViewItem
            thisitem.Text = portMapping.Description
            thisitem.SubItems.Add(portMapping.Protocol)
            thisitem.SubItems.Add(portMapping.ExternalIPAddress)
            thisitem.SubItems.Add(portMapping.ExternalPort.ToString)
            thisitem.SubItems.Add(portMapping.InternalClient)
            thisitem.SubItems.Add(portMapping.InternalPort.ToString)

            items2display(i) = thisitem
            i += 1
            BackgroundWorker2.ReportProgress(i)
        Next
    End Sub

    Private Sub BackgroundWorker2_ProgressChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker2.ProgressChanged
        ProgressBar1.Value = e.ProgressPercentage
    End Sub

    Private Sub BackgroundWorker2_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker2.RunWorkerCompleted
        For i = 0 To mappings.Count - 1
            ListView1.Items.Add(items2display(i))
        Next
    End Sub

End Class

The Exception is a NullReferenceException, Caused because either mappings is Null or mappings.count is null... I'm not sure which or how to tell which one. The issue here is that I had this exact code working before, and I added and removed ports from my router while testing.

Once again, Any help would be appreciated.

[formlesstree4]

Make sure UPnP is enabled on your Router. The article says you'll get that error if it's not.

EDIT: The article doesn't say that, but the comments say so:
Lalit Kapoor had the problem of

NATUPNPLib.IStaticPortMappingCollection mappings = upnpnat.StaticPortMappingCollection;

Always being null. Turns out his router had UPnP disabled.

[stepdragon]

Sweet, thanks.

UPNP is enabled on my router but my router is a piece of ####. Its the one provided by my cable company so its poor quality. But I guess that's a good thing because I can't assume my userbase will be using good hardware and now I can handle that exception when it occurs.

(basically even though upnp was enabled on my router, it didn't act like it becuase it sucks)

but now that I know that I'm not as worried.