[ winsock file transfer tutorial ]

<p>This tutorial shows how to transfer file of any size using winsock control.<br>
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open vb<br>
select standard exe<br>
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press cntrl+t to show the add component window<br>
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select winsock control and microsoft common dialog<br>
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add one winsock control in the project--name it winsock1<br>
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if you want to add chat then add another winsock and name it winsock2<br>
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insert another winsock object if you want to add chat also<br>
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add a microsoft common dialog box --- name it cd<br>
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we will use this winsock1 object to transfer the file and winsock2 for chat<br>
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The basic idea :<br>
To send a file of any size to any ip using winsock first we have to open the file in binary mode.<br>
then get chunks of data from it, chunk is a constant which is initialized to 8000, so we get 8000<br>
bytes of data each time and send it using winsock to the client.<br>
for example let "fname" be the string variable containg the file name then :<br>
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Private Const chunk = 8000<br>
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dim fname as string 'get the name of the file<br>
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Open fname For Binary As #1<br>
Do While Not EOF(1)<br>
data = Input(chunk, #1)<br>
winsock1,sendata data<br>
DoEvents<br>
loop<br>
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this will send 8000bytes of data from the file until the file ends.<br>
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but before sending data from file to client we must send info about the file <br>
like..the name of the file...the extension...etc<br>
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so when send is clicked first check wether a file is there i mean check wether something<br>
is typed in the text box and if yes check wether the file exists<br>
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if both the above conditions are met then get the filename with the extension.<br>
send the file name to the client with "rqst" in front.<br>
for eg. if the name of file is "text.txt" then send "rqsttext.txt" to the client<br>
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the client will then get the file name and display a msgbox with the name of the<br>
file and the user will be given a choice wether to accept the file or not<br>
if he\she selects yes then the client sends "okay" to the server and if he\she selects <br>
no then it sends "deny" to the server..this data i.e. "okay" or '"deny" arrivers on winsock1's<br>
local port the data is then checked using select case if its okay then "send" function<br>
is called with file address as an argument and send button and all buttons and text boxes<br>
associated with send file are disabled.<br>
If the response from client is "deny" then a msgbox is shown on server saying that the<br>
request to send the file .... as been denied..the user can send another request..or <br>
ask the client's user to accept the file using the chat module...<br>
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this is called when send is clicked<br>
private sub send_click()<br>
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'GET FILE NAME<br>
'using getfilename function to get the file name<br>
dim fnamea as string<br>
dim fname as string<br>
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if text1.text = "" then<br>
msgbox "Please type the file name!!!", ,"Manjit"<br>
exit sub<br>
end if<br>
fname = text1.text<br>
'checking wether the file exists<br>
If Dir(fname) = "" Then<br>
MsgBox "File Does not exist Exists", ,"manjit"<br>
exit sub 'exiting sub it file does not exists<br>
end if<br>
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fnamea=GetFileName(text1.text)<br>
fname=text2.text<br>
dim temp as string<br>
temp= "rqst" & fnamea<br>
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'SEND<br>
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winsock1.senddata temp 'sending file name of file<br>
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end sub <br>
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now the request is sent to the client<br>
then the server has to wait for the client's response<br>
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this event is called when data arrives on winsock1<br>
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Private Sub winsock1_dataarrival(ByVal bytestotal As Long)<br>
Dim response As String<br>
Winsock1.GetData response, vbString<br>
Select Case response<br>
Case "okay"<br>
send fname 'send function is called with file name as argument<br>
Case "deny"<br>
MsgBox "Your request to send the file " & fname & " has been denied", , "manjit" 'message when request is denied<br>
End Select<br>
End Sub<br>
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The send function which actally sends the file<br>
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Private Sub send(fname As String)<br>
Command2.Enabled = False<br>
Command3.Enabled = False<br>
Text1.Enabled = False<br>
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Dim data As String<br>
Dim a As Long<br>
Dim data1 As String<br>
Dim data2 As String<br>
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Open fname For Binary As #1<br>
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Do While Not EOF(1)<br>
data = Input(chunk, #1)<br>
Winsock1.SendData data<br>
DoEvents<br>
Loop<br>
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Winsock1.SendData "EnDf"<br>
Close #1<br>
Command2.Enabled = True<br>
Command3.Enabled = True<br>
Text1.Enabled = True<br>
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End Sub<br>
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'Other supporting functions: <br>
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Function GetFileName(attach_str As String) As String<br>
 Dim s As Integer<br>
 Dim temp As String<br>
 s = InStr(1, attach_str, "\")<br>
 temp = attach_str<br>
 Do While s > 0<br>
  temp = Mid(temp, s + 1, Len(temp))<br>
  s = InStr(1, temp, "\")<br>
 Loop<br>
 GetFileName = temp<br>
End Function<br>
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On the client side : <br>
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set winsock1 to listen to a particular port say : 165<br>
and winsoc2 if you want chat too :166<br>
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winsock1 is listening to port 165 and winsock2 is listening to port 166<br>
on the client side<br>
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so when connection request arrives :<br>
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private sub winsock1_connectionrequest(byval idrequest as long)<br>
if winsock1.state <> sckConnected then<br>
winsock1.close<br>
winsock1.accept idrequest<br>
end if<br>
end sub<br>
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and:<br>
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private sub winsock2_connectionrequest(byval idrequest as long)<br>
if winsock2.state <> sckConnected then<br>
winsock2.close<br>
winsock2.accept idrequest<br>
end if<br>
end sub<br>
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DATA ARRIVAL:<br>
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and when data arrives<br>
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Private Sub winsock1_dataarrival(ByVal bytestotal As Long)<br>
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Dim data As String<br>
Dim data4 As String<br>
Dim data2 As String<br>
Dim data3 As String<br>
Dim data5 As String<br>
Dim data6 As String<br>
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Winsock1.GetData data, vbString<br>
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data2 = Left(data, 4)<br>
Select Case data2<br>
Case "rqst" 'file request arrives<br>
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data3 = Right(data, Len(data) - (4)) 'Get the file name<br>
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Dim msg1 As Integer 'Stores user's selection<br>
msg1 = MsgBox(Winsock1.RemoteHost & " wants to send you file " & data3 & " accept ? ", vbYesNo, "Manjit") 'msgbox displayed<br>
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If msg1 = 6 Then 'if user selects yes<br>
Winsock1.SendData "okay"<br>
cd.FileName = data3<br>
data5 = Split(data3, ".")(1)<br>
data6 = "*." & data5<br>
cd.DefaultExt = "(data6)"<br>
data4 = App.Path & "\" & data3<br>
'MsgBox data5<br>
'cd.ShowSave<br>
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Open data4 For Binary As #1<br>
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Else<br>
Winsock1.SendData "deny"<br>
Exit Sub<br>
End If<br>
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Case "EnDf"<br>
Label1.Caption = "File revieved.Size of file : " & sz & " Kb"<br>
size=0<br>
sz=o<br>
Close #1<br>
Case Else<br>
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size = size + 1<br>
Label1.Caption = size * 8 & "Kb Recieved"<br>
sz = size * 8<br>
Put #1, , data<br>
End Select<br>
End Sub<br>
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This will take care of file transfer now for the chat:<br>
we will be using winsock2 for chat:<br>
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On server side :<br>
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WHEN SEND IS CLICKED<br>
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Private Sub Command1_Click()<br>
Dim chat As String<br>
chat = Text1.Text<br>
List1.AddItem (chat)<br>
Winsock2.SendData chat<br>
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End Sub<br>
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when data arrives :<br>
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Private Sub winsock2_dataarrival(ByVal bytestotal As Long)<br>
Dim cht As String<br>
Winsock2.GetData cht, vbString<br>
List1.AddItem (cht)<br>
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End Sub<br>
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the same will be on the client side also...if you want a better chat client then visit<br>
my tutorial on planet source code.com :<br>
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http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=59417&lngWId=1<br>
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or mail for the tutorial...<br>
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I've included a copy of this tutorial in the zip file(tutorial.txt)<br>
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Hope you liked it!!!..PLEASE RATE ME!!!!!!!!!<br>
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