FTP XCRC

Download: Chilkat .NET Assemblies

Demonstrates how to tell Chilkat FTP2 to automatically verify an upload using XCRC. XCRC is an FTP extension supported by most FTP servers. If your FTP server does not support XCRC, then no XCRC command will be sent to verify the upload.

The XCRC command asks the FTP server to send an CRC checksum (hash) for the contents of a file. The client can then verify that the checksum matches the local file. The FTP2 Put* methods automatically do this when the AutoXcrc property is turned on.

Note: In order for the FTP2 component to know whether XCRC is supported by your FTP server, you must have the AutoFeat property turned on (which is the default setting). The AutoFeat property tells the FTP2 component to automatically request the FTP server features via the FEAT command after connecting.

Note: XCRC is new functionality that is present in the pre-release downloads at http://www.chilkatsoft.com/preRelease.asp, or in official new versions dated after 30-Oct-2007. If you have trouble, please contact support@chilkatsoft.com.

Dim ftp As New Chilkat.Ftp2()

Dim success As Boolean

'  Any string unlocks the component for the 1st 30-days.
success = ftp.UnlockComponent("Anything for 30-day trial")
If (success <> true) Then
    MsgBox(ftp.LastErrorText)
    Exit Sub
End If


ftp.Hostname = "www.example-code.com"
ftp.Username = "****"
ftp.Password = "****"

'  Turn on the AutoXcrc property:
ftp.AutoXcrc = true

'  Turn on session logging.  We'll want to examine it to
'  see the XCRC command:
ftp.KeepSessionLog = true

'  Connect and login to the FTP server.
success = ftp.Connect()
If (success <> true) Then
    MsgBox(ftp.LastErrorText)
    Exit Sub
End If


'  Change to the remote directory where the file will be uploaded.
success = ftp.ChangeRemoteDir("junk")
If (success <> true) Then
    MsgBox(ftp.LastErrorText)
    Exit Sub
End If


'  Upload a file.
Dim localFilename As String
localFilename = "hamlet.xml"
Dim remoteFilename As String
remoteFilename = "hamlet.xml"

success = ftp.PutFile(localFilename,remoteFilename)
If (success <> true) Then
    MsgBox(ftp.LastErrorText)
    Exit Sub
End If


'  If we examine the session log, we'll see the XCRC command:
TextBox1.Text = TextBox1.Text & ftp.SessionLog & vbCrLf
TextBox1.Refresh()

ftp.Disconnect()

MsgBox("File Uploaded!")

'  Here is the session log showing the XCRC command:

'  220 Serv-U FTP Server v6.3 for WinSock ready...
'  .
'  USER example-code.com
'  331 User name okay, need password.
'  .
'  PASS ****
'  230 User logged in, proceed.
'  .
'  TYPE I
'  200 Type set to I.
'  .
'  SYST
'  215 UNIX Type: L8
'  .
'  FEAT
'  211-Extension supported
'   CLNT
'   MDTM
'   MDTM YYYYMMDDHHMMSS[+-TZ];filename
'   SIZE
'   SITE PSWD;EXEC;SET;INDEX;ZONE;CHMOD;MSG
'   REST STREAM
'   XCRC filename;start;end
'   MODE Z
'   MLST Type*;Size*;Create;Modify*;Win32.ea*;
'  211 End
'  .
'  CWD junk
'  250 Directory changed to /junk
'  .
'  PORT 192,168,1,103,5,144
'  200 PORT Command successful.
'  .
'  STOR hamlet.xml
'  150 Opening BINARY mode data connection for hamlet.xml.
'  226 Transfer complete.
'  .
'  XCRC hamlet.xml
'  250 3C1933BF