VPN Forum access and IP addresse Tests

**DocAElstein** · 12-31-2018, 12:43 AM

Local Host address, Computer name
There are a couple of Win32 APIs which will get this information.
We just need to write a small amount of coding to get the function to do what we want and also a bit of manipulaation to give the information as we need it.
For the computer name this is simply a function to give us a string.

Code:

Option Explicit
Private Declare Function GetComputerName Lib "kernel32" Alias "GetComputerNameA" (ByVal lpBuffer As String, ByRef nSize As Long) As Long
'  "GetComputerNameA" (ByVal lpBuffer As String, ByRef nSize As Long) As Long
Function ComputerName() As String                                                                                                                                                                        ' GHB and sex..
Dim NmeLen As Long, lngX As Long, strCompName As String
 Let NmeLen = 999: Let strCompName = "                                     "     ' variables must be initialised or API things often dont work                                                            ' String$(50, 0)
 Let lngX = GetComputerName(strCompName, NmeLen) '
    If lngX <> 0 Then ' returns 1 if it works
     Let ComputerName = strCompName '   Left$(strCompName, NmeLen)   ' The first argument variable gets like a LSet done on it
    Else
     Let ComputerName = "Couldn't get Computer name"
    End If
 Let ComputerName = Left$(ComputerName, NmeLen) ' We must do this as there is a  Chr(0)  after the name ....  Let ComputerName = Trim(ComputerName) ' this is no good, - it leaves Chr(0) on the end which means that ComputerName is the last thing that will get printed
 'Call WtchaGot(ComputerName)
End Function

The Win32 API for the local IP address is slightly more complicated. It will give us a table/ array of all the IP addresses held. The first is generally that we are interested in. it seems to be added when a VPN connection is made

Code:

Option Explicit
Private Declare Function GetIpAddrTable_API Lib "IpHlpApi" Alias "GetIpAddrTable" (ByRef pIPAddrTable As Any, ByRef pdwSize As Long, ByVal bOrder As Long) As Long    '   http://www.source-code.biz/snippets/vbasic/8.htm
'  "GetIpAddrTable" (ByRef pIPAddrTable As Any, ByRef pdwSize As Long, ByVal bOrder As Long) As Long
Public Function GetIpAddrTable() As String  '       Christian d'Heureuse, www.source-code.biz  http://www.source-code.biz/snippets/vbasic/8.htm
Rem 1 We give the API function some info , and that seems to make it fill up an array with table values
Dim Buf(0 To 1234) As Byte ' Buf(0 To 511) As Byte ' must be Byte or overflow at NrOfEntries
Dim BufSize As Long: Let BufSize = 12345
Dim rc As Long: Let rc = GetIpAddrTable_API(Buf(0), BufSize, 1)
   'If rc <> 0 Then Err.Raise vbObjectError, , "GetIpAddrTable failed with return value " & rc
Dim NrOfEntries As Integer: NrOfEntries = Buf(1) * 256 + Buf(0)
   'If NrOfEntries = 0 Then GetIpAddrTable = Array(): Exit Function

Dim i As Long
   For i = 0 To NrOfEntries - 1
    Dim j As Long, s As String
      For j = 0 To 3
      Dim Indcy As Long: Let Indcy = 4 + i * 24 + j
       s = s & IIf(j > 0, ".", "") & Buf(Indcy): Debug.Print Indcy & "   " & Buf(Indcy) ' This code line just builds the final string for each IP address, with a "." before all but the first of the 4 number parts  ---  for example like  192 . 168 . 2 . 110
      Next j
     Dim strIPs As String: Let strIPs = strIPs & "   " & s: Let s = ""
    Next
   GetIpAddrTable = strIPs: Debug.Print strIPs
End Function

'    4   127
'    5   0
'    6   0
'    7   1
'    28   192
'    29   168
'    30   2
'    31   110
'       127.0.0.1   192.168.2.110                                                                                          ' _

'    4   10
'    5   132
'    6   13
'    7   113
'    28   127
'    29   0
'    30   0
'    31   1
'    52   192
'    53   168
'    54   2
'    55   110
'       10.132.13.113   127.0.0.1   192.168.2.110
'     1  2  3    4   5   6  7      8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
'    25 26 27   28  29  30  31     32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
'    49 50 51   52  53  54  55
'               10  132  13  127
'               127  0   0   1
'               192 168  2  110

If we examine that coding above, and experiment with what it does, we see a couple of things:
Rem 1
_ It is doing a strange thing, as API's often do. That is to say the API works similarly to a normal VBA function, except the way each argument is a mystery.. following some set of rules/coding which probably the author wrote when he was drunk and no one can remember anymore.
You must make an array of Byte types. The array should be fairly big.
You must give the first array element and the size of the array to the API Function.
Then magically the array gets filled. Presumably some internally held table is put into the array
Rem 2
A bit of maths is done to pick out the elements we want from the returned filled array

The final analysis here of a typical output can be helpful to try and understand another way to get this information

Code:

'     1  2  3    4   5   6  7      8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
'    25 26 27   28  29  30  31     32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
'    49 50 51   52  53  54  55
'               10  132  13  127
'               127  0   0   1
'               192 168  2  110

Or maybe not. I am not sure. I doubt many people are…