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 I have been textbook programming out of a book called network programming in.net in the book instructs me to go to a couple of sites and download winpcap and rvpacket because we will need these two to build the next project well I did so I have completed the project everything looked good until I run the project I get the error "An unhandled exception of type 'System.NullReferenceException' occurred in WebInfo.exe Additional information: Object reference not set to an instance of anobject."
at the beginning of the project it did tell me to add a reference to Microsoft.visualbasic.compatibility I am at a complete loss could someone please help me the error is on the line below "packetquery = checkpacket query(adapter)"
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Option Strict Off
Public Class Form1
Inherits System.Windows.Forms.Form
Private Sub btnstart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnstart.Click
Dim Qid As Short
Dim PacketBuffer As String
Dim Adapters() As String
Dim openSuccess As Short
Dim PacketQueue As Short
Dim PacketLen As Short
Dim rawAdapterDetails As String
Dim posDefaultAdapter As Short
rawAdapterDetails = Space(MAX_ADAPTER_LEN)
getAdapterNames(rawAdapterDetails)
posDefaultAdapter = rawAdapterDetails.IndexOf(ADAPTER_DELIMITER)
Adapter = rawAdapterDetails.Substring(0, posDefaultAdapter)
openSuccess = openAdapter(Adapter)
If openSuccess <> ERR_SUCCESS Then
MsgBox("unable to start. check wincap is installer")
Exit Sub
End If
Do
PacketQueue = checkPacketQueue(Adapter)
For Qid = 1 To PacketQueue
PacketBuffer = Space(MAX_PACKET_SIZE)
PacketLen = getQueuedPacket(PacketBuffer)
PacketBuffer = PacketBuffer.Substring(0, PacketLen)
tbpackets.Text = tbpackets.Text & Replace(PacketBuffer, Chr(0), "")
tbpackets.SelectionStart = Len(tbpackets.Text)
System.Windows.Forms.Application.DoEvents()
Next
System.Windows.Forms.Application.DoEvents()
Loop
End Sub
Private Sub btnstop_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnstop.Click
closeAdapter(Adapter)
End Sub
Private Declare Function getAdapterNames Lib "rvpacket.dll" (ByVal s As String) As Short
Private Declare Function openAdapter Lib "rvpacket.dll" (ByVal Adapter As String) As Short
Private Declare Function checkPacketQueue Lib "rvpacket.dll" (ByVal Adapter As String) As Short
Private Declare Function getQueuedPacket Lib "rvpacket.dll" (ByVal s As String) As Short
Private Declare Sub closeAdapter Lib "rvpacket.dll" (ByVal Adapter As String)
Private Const SIMULTANEOUS_READS As Short = 10
Private Const MAX_ADAPTER_LEN As Short = 512
Private Const ADAPTER_DELIMITER As String = "|"
Private Const MAX_PACKET_SIZE As Short = 10000
Private Const ERR_SUCCESS As Short = 1
Private Const ERR_ADAPTER_ID As Short = 2
Private Const ERR_INVALID_HANDLE As Short = 3
Private Const ERR_INVALID_ADAPTER As Short = 4
Private Const ERR_ALLOCATE_PACKET As Short = 5
Public Adapter As String
End Class
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Patience! We don't support 3rd party libraries here!
Try changing all your DECLARE statements that are returning Short's to Integer's. The return values coming from the functions in the C++ code are all returning DWORD's, or 32-bit unsigned integers. A Short in VB.NET is a 16-bit signed number, so your losing half of the data that makes up the return values from these functions:
Private Declare Function getAdapterNames Lib "rvpacket.dll" (ByVal s As String) As Integer
Private Declare Function openAdapter Lib "rvpacket.dll" (ByVal Adapter As String) As Integer
Private Declare Function checkPacketQueue Lib "rvpacket.dll" (ByVal Adapter As String) As Integer
Private Declare Function getQueuedPacket Lib "rvpacket.dll" (ByVal s As String) As Integer
Private Declare Sub closeAdapter Lib "rvpacket.dll" (ByVal Adapter As String)
Do the same for your constants:
Private Const SIMULTANEOUS_READS As Integer = 10
Private Const MAX_ADAPTER_LEN As Integer= 512
Private Const ADAPTER_DELIMITER As Integer= "|"
Private Const MAX_PACKET_SIZE As Integer= 10000
Private Const ERR_SUCCESS As Integer= 1
Private Const ERR_ADAPTER_ID As Integer= 2
Private Const ERR_INVALID_HANDLE As Integer= 3
Private Const ERR_INVALID_ADAPTER As Integer= 4
Private Const ERR_ALLOCATE_PACKET As Integer= 5
Then move these two sections to the top of the Class definition. The rest of the code LOOKS right, but I'm in no position to start putting together programs to test this library. Try checking to see what Adapter holds when you make that call to PacketQueue = checkPacketQueue(Adapter). Make sure it's not blank.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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Please Help me to find a particular record in a database using adodc
M.N.Patel
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Hi all
how can I write programe in vb.Net to get thw URL from the address bar when any one use the internet explorer .
Please help me.
Thanks.
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Hello,
I think the title says.
Your help is truly appreciated.
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If you want to write a virus, I reckon C++ is the way to do it. VB.NET isn't even on the list.
Christian
I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer
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Corrupt a folder? Don't ask, noone is telling.
Restrict access to it? Easy using NTFS permissions. Just right-click on the folder, click Properties, Security tab, and set permissions for the various/groups user as needed.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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Hello,
I would like to know how I can change the file/folder index, so the file seems corrupted until I return its original windows index
Your help is truly appreciated.
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????????????????????????????????? What ?????????????????????????????????
I think your talking about intentionally corrupting the file system. Uhhhh ... no, nobody in their right mind is going to take you there. This would require an expert level of knowledge of the NTFS file system and is way beyond the scope of this, or any, forum.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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Hello,
I was able to hide a folder but when the hidden folder is a subfolder and you view to parent folder properties the size of the hidden folder is counted.
I found a program that hides the size completely, how they did it?!
Your help is truly appreciated.
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They wrote an extension to the NTFS file system. No, your not going to get away with doing this in VB6. This is something much better handled in C++. In some cases, the files are not stored in the file system like a normal file, but instead, are stored in a hidden file, like a .ZIP file or a mini file system inside the NTFS file system, and this file is managed by the extension you write.
But like I said, don't even think of doing this in VB6.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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Hello there,
I would like to know how I can encrypt a folder (NOT a file) without third party interaction.
I am sure it's possible because much encryption software does it.
Your help is greatly appreciated.
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This is already handled by NTFS. The contents of the folder is encrypted, not the folder itself.
Once again, it is possible to do in C++. VB6 is seriously outclassed in writing extensions for NTFS.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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i am making project on vb.net ..it is network inventory system.. In that i need to access the linux registry using vb.net..so if you have any idea about that than plz reply me ...
thank you...
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There is nothing in the .NET BCL to do this. I haven't found any documentation on how to do it either. Also, you would probably be better served asking this question on a Linux board, not VB. Without knowing the ins and outs of the Linux registry, it's impossible to tell you what you have to do.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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I am creating a class which uses rsa for encryption and decryption. problem with rsa is that it uses public and private keys which means i also have to store the keys if i want to decrypt something which i don't want. Is there some way to get over this. i know that sha does not require keys but then it only encrypts and you have to match encryption string. Is there a better way to encrypt string and store it and then decrypt it.
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There are many different ways of doing something with the general description that you gave. What you end up doing depends greatly on what your requirements really are and what your doing with the encrypted data. I'd suggest reading up on all the Crypto docs starting here[^] to get a good look at the pitfalls and benefits of using these methods.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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Dear all
Dim ProductAdapter As New OleDb.OleDbDataAdapter( _
"SELECT * FROM TCAP WHERE NTCIDCODE LIKE 'VARIABLE' ", _
sConn)
======================================================
I has a ploblem with VARIABLE String. i want to declare
variable and replace than VARIABLE
Exam : Public const strTest As string = "TEST" i 'm cannot declare strTest variable in sql command like that.
Please help and advise me. Many thaks & best regards
sriwirko
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Declare a variable like strVariable and replace VARIABLE with strVariable but without the single quote. 
Luckyhuss
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thank for you advance
sriwirko
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USE
Public const strTest As string = "TEST"<br />
Dim ProductAdapter As New OleDb.OleDbDataAdapter( _<br />
"SELECT * FROM TCAP WHERE NTCIDCODE LIKE '" & strTest & "' ", _<br />
sConn)
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Hi,
I am partially new to vb.net, but have vb.net standard 2003. I am more interested in microcontroller development, but am working on some software to interface and debug some registers from the microcontrollers RAM.
Using a RS232 connection (with a MsComm wrapper) i am able to get text to and from the controller very easily. But i am not interested in text (ascii) i am interested in the values. So 0x41 sent from the controller appears as a A in the textbox i display it in, but i want to display 0x41.
Any ideas?
I have looked through the help system without too much luck, many thanks in advance.
- Martyn Pittuk
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If you are absolutely sure your input data is all in the form of text ASCII characters, and does not contain binary data, you can convert an ASCII character into it's ASCII integer code, and then convert the integer to Hex format. But the hex will not be in the "0x41" format - you'll just get a "41".
For example:
txtMyTextBox.Text = (Hex(Asc("A")))
will display "41" in the textbox.
The functions will only work with a single character. If you have data in a string you can convert it into an array of characters using the String.ToCharArray function then enumerate each character to convert it to Hex.
Good Luck
Robert
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Ok thanks thats just what i want, the bytes can only be values from 0x00 to 0xFF which is the range of the extended ASCII dataset i think, so Asc should handle it!
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