(Visual Basic 6.0) Transfer a File using Sockets (TLS or non-TLS)

Demonstrates how to two programs, one a socket writer and the other a socket reader, can transfer a file. The connection can be TLS or a regular non-encrypted TCP connection.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

' On the sending side, we'll load the file into a BinData object and send.
' On the receiving side, we'll read from the socket connection into a BinData, and save to a file.
' This example assumes the file is not crazy-large, and that the entire contents
' can fit into memory.  
' (If the file is too large for memory, there are other ways to send. It just involves streaming or 
' sending the file chunk-by-chunk..)

' This section of code is for the sender.
Dim bdToSend As New ChilkatBinData
Dim success As Long
success = bdToSend.LoadFile("somePath/someFile.dat")
' Assume success for the example...

Dim sndSock As New ChilkatSocket
Dim bUseTls As Long
bUseTls = 1
Dim port As Long
port = 5555
Dim maxWaitMs As Long
maxWaitMs = 5000
success = sndSock.Connect("some_domain_or_ip.com",port,bUseTls,maxWaitMs)
' Assume success for the example...

' Tell the receiver how many bytes are coming.
Dim numBytes As Long
numBytes = bdToSend.NumBytes
Dim bBigEndian As Long
bBigEndian = 1
success = sndSock.SendInt32(numBytes,bBigEndian)

' Send the file data (sends the entire contents of bdToSend).
success = sndSock.SendBd(bdToSend,0,0)

' Get an acknowledgement.
success = sndSock.ReceiveInt32(bBigEndian)
If (success <> 1) Then
    Debug.Print sndSock.LastErrorText
    Exit Sub
End If

' Did the receiver get the correct number of bytes?
If (sndSock.ReceivedInt <> numBytes) Then
    Debug.Print "The receiver did not acknowledge with the correct number of bytes."
    Exit Sub
End If

Debug.Print "File sent!"

' ------------------------------------------------------------------------------------
' The code below is for the receiving side (running on some other computer..)

Dim listenSock As New ChilkatSocket

success = listenSock.BindAndListen(5555,25)
If (success <> 1) Then
    Debug.Print listenSock.LastErrorText
    Exit Sub
End If

' Get the next incoming connection
' Wait a maximum of 20 seconds (20000 millisec)
Dim rcvSock As ChilkatSocket
Set rcvSock = listenSock.AcceptNextConnection(20000)
If (listenSock.LastMethodSuccess = 0) Then
    Debug.Print listenSock.LastErrorText
    Exit Sub
End If

' The sender will first send the big-endian integer for the number of bytes
' that are forthcoming..
success = rcvSock.ReceiveInt32(bBigEndian)
If (success <> 1) Then
    Debug.Print rcvSock.LastErrorText

    Exit Sub
End If

Dim numBytesComing As Long
numBytesComing = rcvSock.ReceivedInt

' Receive that many bytes..
Dim bdReceived As New ChilkatBinData
success = rcvSock.ReceiveBdN(numBytesComing,bdReceived)
If (success <> 1) Then
    Debug.Print rcvSock.LastErrorText

    Exit Sub
End If

' Acknowledge the sender by sending back the number of bytes we received.
success = rcvSock.SendInt32(bdReceived.NumBytes,bBigEndian)

' Close the connection.
Dim maxWaitMs As Long
maxWaitMs = 20
success = rcvSock.Close(maxWaitMs)

' Save the received data to a file.
success = bdReceived.WriteFile("somePath/someFile.dat")
' Assume success for the example...

Debug.Print "File received!"