Download file to byte array using SSH.NET (VB.NET)

Question

I would like to download a file from SFTP using the SSH.NET library. However, I would like this file to be received in Byte array. Thus, this file must be stored in memory .

Here's how I do it

Sub Main()
   Dim client As SftpClient = New SftpClient(hostname, username, password)
   client.Connect()
   Using b As System.IO.Stream = client.OpenRead("/www/Server.exe")
        Dim data() As Byte = GetStreamAsByteArray(b)
   End Using
End Sub

Public Shared Function GetStreamAsByteArray(ByVal stream As System.IO.Stream) As Byte()
    Dim streamLength As Integer = Convert.ToInt32(stream.Length)

    Dim fileData As Byte() = New Byte(streamLength) {}

    ' Read the file into a byte array
    stream.Read(fileData, 0, streamLength)
    stream.Flush()
    stream.Close()

    Return fileData
End Function

However this method does not work: indeed, by writing it on the disk to test it, it is corrupted.

Answer 1

Your code is imo more or less correct. The only problem is that, in VB.NET, the New Byte(X) does allocate an array one byte longer than you want: 0..X (not 1..X or 0..X-1 as you might have expected).

So if you then save the complete array (eg by File.WriteAllBytes ) and not only stream.Length bytes, the file will be one byte larger, with an additional trailing NULL byte.

This is correct:

Dim fileData As Byte() = New Byte(streamLength - 1) {}