[CANCLED] libssh2.dll SFTP transfer

[Roger Cabo]

Hi everyone,

today I tried to build a program to send and receive files from a SFTP webserver. (same easy as FTP but port 22)
I build the whole code step by step. I didn't expect to get the following error.

I downloaded the 32bit libssh2.dll from the secure website de.dll-files.com/libssh2.dll.html

And and copy it into the soucecode folder, CurDir() show the correct path where libssh2.dll is located.

Does the error mean:
Gb32 does not find the function inside of the dll? or
It doesn't find the DLL?

Any idea what this error cause? 



$Library "gfawinx"
$Library "UpdateRT"
UpdateRuntime      ' Patches GfaWin23.Ocx

Const LIBSSH2_FXF_WRITE = 2
Const LIBSSH2_FXF_CREAT = 8
Const LIBSSH2_FXF_TRUNC = 16

' Zugriffsrechte für die erstellte Datei
Const LIBSSH2_SFTP_S_IRUSR = 256
Const LIBSSH2_SFTP_S_IWUSR = 128
Const LIBSSH2_SFTP_S_IRGRP = 32
Const LIBSSH2_SFTP_S_IROTH = 4

' Erforderliche DLL-Aufrufe
Declare Function libssh2_init Lib "libssh2.dll" () As Integer
Declare Function libssh2_exit Lib "libssh2.dll" () As Integer
Declare Function libssh2_session_init_ex Lib "libssh2.dll" (ByVal alloc_func As Long, ByVal free_func As Long, ByVal realloc_func As Long, ByVal context As Long) As Long
Declare Function libssh2_session_free Lib "libssh2.dll" (ByVal session As Long) As Integer
Declare Function libssh2_session_disconnect Lib "libssh2.dll" (ByVal session As Long, ByVal description As String) As Integer
Declare Function libssh2_session_set_blocking Lib "libssh2.dll" (ByVal session As Long, ByVal blocking As Integer) As Integer
Declare Function libssh2_session_handshake Lib "libssh2.dll" (ByVal session As Long, ByVal socket As Long) As Integer
Declare Function libssh2_userauth_password Lib "libssh2.dll" (ByVal session As Long, ByVal username As String, ByVal password As String) As Integer
Declare Function libssh2_sftp_init Lib "libssh2.dll" (ByVal session As Long) As Long
Declare Function libssh2_sftp_shutdown Lib "libssh2.dll" (ByVal sftp As Long) As Integer
Declare Function libssh2_sftp_open Lib "libssh2.dll" (ByVal sftp As Long, ByVal filename As String, ByVal flags As Long, ByVal mode As Long) As Long
Declare Function libssh2_sftp_close Lib "libssh2.dll" (ByVal handle As Long) As Integer
Declare Function libssh2_sftp_write Lib "libssh2.dll" (ByVal handle As Long, ByVal buffer As String, ByVal count As Long) As Long

' Beispielcode für die Verwendung der libssh2.dll
Dim session As Long
Dim sftp As Long
Dim sock As Long
Dim username As String
Dim password As String
Dim remotePath As String
Dim localPath As String
Dim remoteHandle As Long
Dim localHandle As Integer
Dim buffer1 As String
Dim bytesRead As Long

' Initialisieren der libssh2.dll
libssh2_init() // <------------------- ERROR

' Initialisieren der Session
session = libssh2_session_init_ex(0, 0, 0, 0)

' Verbindung zum Server herstellen. Port 22
sock = ConnectToServer("myserver.com", 22)

' Handshake durchführen
libssh2_session_handshake(session, sock)

' Authentifizieren mit Benutzername und Passwort
username = "meinbenutzername"
password = "meinpasswort"
libssh2_userauth_password(session, username, password)

' SFTP-Session initialisieren
sftp = libssh2_sftp_init(session)

' Datei auf dem Server öffnen
remotePath = "/pfad/auf/datei.txt"
localPath = "C:\mein\lokales\verzeichnis\datei.txt"
remoteHandle = libssh2_sftp_open(sftp, remotePath, LIBSSH2_FXF_WRITE Or LIBSSH2_FXF_CREAT Or LIBSSH2_FXF_TRUNC, LIBSSH2_SFTP_S_IRUSR Or LIBSSH2_SFTP_S_IWUSR Or LIBSSH2_SFTP_S_IRGRP Or LIBSSH2_SFTP_S_IROTH)

' Datei auf dem Server schreiben
localHandle = FreeFile
Open localPath for Binary Access Read As # localHandle
buffer1 = String(1024, #0)
Do While Not EOF(# localHandle)

 // !!!FIX THIS!!! create a custom function for Input that return the available size of bytes as well and fill the buffer
 'bytesRead = Input #localHandle, buffer
   
 libssh2_sftp_write(remoteHandle, buffer1, bytesRead)
Loop
Close # localHandle

' Datei auf dem Server schließen
libssh2_sftp_close(remoteHandle)

' SFTP-Session beenden
libssh2_sftp_shutdown(sftp)

' Session beenden
libssh2_session_disconnect(session, "")
libssh2_session_free(session)
libssh2_exit()


Function ConnectToServer(ByVal server As String, ByVal port As Integer) As Long
 
 Declare Function socket Lib "wsock32.dll" (ByVal af As Long, ByVal socktype As Long, ByVal protocol As Long) As Long
 Declare Function connect Lib "wsock32.dll" (ByVal sock As Long, ByRef name As SOCKADDR_IN, ByVal namelen As Long) As Long
 Declare Function inet_addr Lib "wsock32.dll" (ByVal cp As String) As Long
 Declare Function closesocket Lib "wsock32.dll" (ByVal socket As Long) As Long
 
 Type IN_ADDR
   s_addr As Long
 End Type
 
 Type SOCKADDR_IN
   sin_family As Integer
   sin_port As Integer
   sin_addr As IN_ADDR
   sin_zero As String * 8
 End Type
 
 Const AF_INET = 2
 Const SOCK_STREAM = 1
 Const IPPROTO_TCP = 6
 
 Dim ipAddr As Long
 Dim sock As Long
 Dim sockaddr As SOCKADDR_IN
 
 ' IP-Adresse des Servers abrufen
 ipAddr = inet_addr(server)
 
 ' Socket-Adresse vorbereiten
 Const AF_INET As Integer = 2
 sockaddr.sin_family = AF_INET
 sockaddr.sin_port = htons(port)
 sockaddr.sin_addr.s_addr = ipAddr
 
 ' Socket öffnen
 sock = socket(AF_INET, SOCK_STREAM, 0)
 If sock < 0 Then
   MsgBox "Socket konnte nicht geöffnet werden"
   Exit Function
 End If
 
 ' Verbindung zum Server herstellen
 // Declare Function connect Lib "wsock32.dll" (ByVal sock As Long, ByRef name As SOCKADDR, ByVal namelen As Long) As Long
 If connect(sock, sockaddr, Len(sockaddr)) < 0 Then
   MsgBox "Verbindung konnte nicht hergestellt werden"
   closesocket(sock)
   Exit Function
 End If
 
 ConnectToServer = sock
End Function


Function inet_addr(ByVal address As String) As Long
 Dim arrOctets() As String
 Dim lAddr As Long
 Dim i As Integer
 
 SplitString(arrOctets(), address, ".")
 
 If UBound(arrOctets()) <> 3 Then
   inet_addr = 0
   Exit Function
 End If
 
 For i = 0 To 3
   If Not IsNumeric(arrOctets(i)) Then
     inet_addr = 0
     Exit Function
   End If
   
   If CInt(arrOctets(i)) < 0 Or CInt(arrOctets(i)) > 255 Then
     inet_addr = 0
     Exit Function
   End If
   
   lAddr = lAddr Or Val(arrOctets(i)) * (256 ^ i)
 Next i
 
 Return lAddr
End Function

Procedure SplitString(ByRef arrOctets() As String, ByVal s As String, ByVal separator As String)
 Dim parts() As String
 Dim start As Integer, ende As Integer, i As Integer
 start = 1
 i = 0
 Do While ende < Len(s)
   ende = InStr(start, s, separator)
   If ende = 0 Then ende = Len(s) + 1
   ReDim parts(i)
   parts(i) = Mid(s, start, ende - start)
   i++
   start = ende + 1
 Loop
EndProc


[(X)]

Since this function returns an integer value, the first thing I would try:

~libssh2_init()   // Which ignores the returned value.

or

Dim r
r = libssh2_init()   // Which provides a variable to receive the return value.

[dragonjim]

Hi,

It means that GFA can not find the parent library, as far as I can tell.

[(X)]

Could this be the reason?

Perhaps the dll is not registered...

helpdeskgeek.com/how-to/register-dll-file-in-windows/

Also, ChatGPT suggests:

Consider using a different SSH library if you continue to have trouble with libssh2. There are other SSH libraries available that may be easier to use with Visual Basic, such as WinSCP or PuTTY.

[Roger Cabo]

I got loading the libssh2.DLL to work. I compiled the complete libssh2 library in VS2017 containing CMAKE and installing OpenSSH2 for 32bit.

That took me about 5h with help from CHatGPT 3.5.. yayyyy!

32bit is so out of any use case.. ouch!

Reason for the previous errors:  The libssh2.DLL from the original website was not intend to run as a Registered DLL or OCX. The register entry points are not compiled into the DLL.

Same with the WinSCnet.DLL, ist required to get the authentication SHA256 Key from the server.

The code is only 50 lines.. But feels like 15.000 lines containing infinite trouble.
Too tired, too late, too test the final result if it connects.

[Roger Cabo]

I canceled the libssh2.dll project of to many problems. After building the dll, the next error occurred on ConnectToSFTP() and it does not login for any reason: Error 100049

Now I rent a VServer for only 6€ a month and being able to cancel the subscription each month.
Perhaps I got a super save configuration to work. ChatGPT 4.0 is very helpful in this case





 

[(X)]

I have not gone too far in the SSH rabbit hole yet. 

A quick glance at ChatGPT's (likely incomplete) VB6 example code and it seems like you need to juggle a lot of balls (API functions) at a time.

This is ChatGPT's answer to: "What is an example of use in vb6 for a client server transfer of a text file?"

' Add a reference to the libssh2.dll library in your project

Private Declare Function libssh2_init Lib "libssh2.dll" () As Long
Private Declare Function libssh2_exit Lib "libssh2.dll" () As Long
Private Declare Function libssh2_session_init_ex Lib "libssh2.dll" (ByVal fd As Long, ByVal heartbeat As Long, ByVal hostname As String, ByVal port As Integer) As Long
Private Declare Function libssh2_session_set_timeout Lib "libssh2.dll" (ByVal session As Long, ByVal timeoutType As Integer, ByVal timeoutMilliseconds As Long) As Long
Private Declare Function libssh2_userauth_password Lib "libssh2.dll" (ByVal session As Long, ByVal username As String, ByVal password As String) As Long
Private Declare Function libssh2_scp_send64 Lib "libssh2.dll" (ByVal session As Long, ByVal path As String, ByVal mode As Integer, ByVal length As Long) As Long
Private Declare Function libssh2_scp_send_ex Lib "libssh2.dll" (ByVal session As Long, ByVal path As String, ByVal mode As Integer, ByVal length As Long, ByVal mtime As Integer, ByVal atime As Integer) As Long
Private Declare Function libssh2_scp_recv Lib "libssh2.dll" (ByVal session As Long, ByVal path As String, ByRef sb As Long) As Long
Private Declare Function libssh2_channel_open_session Lib "libssh2.dll" (ByVal session As Long) As Long
Private Declare Function libssh2_channel_exec Lib "libssh2.dll" (ByVal channel As Long, ByVal command As String) As Long
Private Declare Function libssh2_channel_read Lib "libssh2.dll" (ByVal channel As Long, ByVal buffer As String, ByVal buflen As Integer) As Integer
Private Declare Function libssh2_channel_write Lib "libssh2.dll" (ByVal channel As Long, ByVal buffer As String, ByVal buflen As Integer) As Integer
Private Declare Function libssh2_channel_send_eof Lib "libssh2.dll" (ByVal channel As Long) As Long
Private Declare Function libssh2_channel_close Lib "libssh2.dll" (ByVal channel As Long) As Long
Private Declare Function libssh2_channel_free Lib "libssh2.dll" (ByVal channel As Long) As Long
Private Declare Function libssh2_session_disconnect Lib "libssh2.dll" (ByVal session As Long, ByVal description As String) As Long
Private Declare Function libssh2_session_free Lib "libssh2.dll" (ByVal session As Long) As Long

Public Sub SshTransferTextFile(ByVal host As String, ByVal username As String, ByVal password As String, ByVal localFilePath As String, ByVal remoteFilePath As String)
   Dim sshSession As Long
   Dim sshChannel As Long
   Dim fileHandle As Long
   Dim bytesRead As Integer
   Dim buffer As String * 2048
   
   ' Initialize the libssh2 library
   If libssh2_init() <> 0 Then
       MsgBox "Failed to initialize libssh2"
       Exit Sub
   End If
   
   ' Connect to the SSH server
   sshSession = libssh2_session_init_ex(0, 0, host, 22)
   If sshSession = 0 Then
       MsgBox "Failed to connect to SSH server"
       libssh2_exit()
       Exit Sub
   End If
   
   ' Set a timeout of 10 seconds for the session
   libssh2_session_set_timeout sshSession, 1, 10000

   ' Authenticate with the server using a password
   If libssh2_userauth_password(sshSession, username, password) <> 0 Then
     MsgBox "Failed to authenticate with SSH server"
     libssh2_session_disconnect sshSession, ""
     libssh2_session_free sshSession
     libssh2_exit()
     Exit Sub
   End If

   ' Open an SSH channel for executing commands
   sshChannel = libssh2_channel_open_session(sshSession)
   If sshChannel = 0 Then
       MsgBox "Failed to open SSH channel"
       libssh2_session_disconnect sshSession, ""
       libssh2_session_free sshSession
       libssh2_exit()
       Exit Sub
   End If

   ' Send a command to create the remote file
   If libssh2_channel_exec(sshChannel, "touch " & remoteFilePath) <> 0 Then
       MsgBox "Failed to execute remote command"
       libssh2_channel_free sshChannel
       libssh2_session_disconnect sshSession, ""
       libssh2_session_free sshSession
       libssh2_exit()
       Exit Sub
   End If
   
   ' Send the local file to the remote server
   fileHandle = FreeFile
   Open localFilePath For Binary As #fileHandle
   libssh2_scp_send64 sshSession, remoteFilePath, 0644, FileLen(localFilePath)
   Do While Not EOF(fileHandle)
       bytesRead = InputB(2048, fileHandle)
       buffer = Space(bytesRead)
       Get #fileHandle, , buffer
       libssh2_channel_write sshChannel, buffer, bytesRead
   Loop
   Close #fileHandle
   
   ' Send an end-of-file signal to the remote server
   libssh2_channel_send_eof sshChannel
   
   ' Close the SSH channel and session
   libssh2_channel_close sshChannel
   libssh2_channel_free sshChannel
   libssh2_session_disconnect sshSession, ""
   libssh2_session_free sshSession
   libssh2_exit()
   
   MsgBox "File transfer complete"
EndSub



In this example, the `SshTransferTextFile` function connects to an SSH server using the specified username and password, creates a remote file on the server using the `touch` command, and then sends the contents of the local text file to the remote server using SCP (Secure Copy) protocol. Once the transfer is complete, the SSH channel and session are closed, and a message box is displayed to indicate the completion of the transfer.

[Roger Cabo]

Or I don't know how. Gb32 does not find the entry points of the libssh2.dll.
And I was not able to use it asynchronous with code.

So I rented a new V-Server + proftp. proftp is a server based module and can handle FTP plain connections.
I use my FTP plain ftp.dll and reconfigure the V-server to managing the connection to secure.

This require to code PHP scripts.. chatGPT 4.0 is a great help, but makes a lot errors sometimes.
But step by step I will be able to create a incredible secure connection to GB32.

I took me several days to develop an incredible secure system. Then I explained and ask chat GPT for security reasons in this case:


The likelihood of a successful attack in which data is stolen and decrypted is extremely low due to the implemented security measures.
It is difficult to provide an exact number for the likelihood of a successful attack, as this depends on many factors,
such as the type of targeted systems, the capabilities of the attackers, and the available security measures.

Based on the security measures described in this assessment, the likelihood of a successful attack is very low.
A rough estimate could suggest that it would take thousands or even tens of thousands of attacks before one would be successful - if at all.
This estimate highlights the difficulty for even experienced hackers to successfully penetrate the system and extract data due to the strict limitations and security precautions that have been implemented.

Considering these statistics, the likelihood of a successful attack on the system, particularly in terms of decrypting data, is almost negligible.