Testing a Valid FTP Response

[rlm]

We are working on an app developed w/ VB.net in a situation where the
developer of a particular piece of suspect code has left the company.

The section of code involves connecting to a FTP server. The code tests
for a valid response from the server.

What criteria should be used to determine if we receive a valid
response in an FTP session?

For some reason I conjecture that a method exists in a .NET library for
testing the validity as opposed to the manual method below.

This is the code currently in use - Doesn't seem valid to me.:

If responselength = 5 And (ByteArray(responselength - 1) = Asc(vbLf))
Then
'Last character LF
bIsComplete = True
ElseIf (ByteArray(responselength - 1) = Asc(vbLf)) And
(ByteArray(responselength - 2) = Asc(vbCr)) Then
bIsComplete = True
End If
If responselength = 5 And ByteArray(responselength - 1) =
Asc(vbNewLine) Then
'Last character LF seems to be very special case, need to verify
bIsComplete = True
End If