(VB.NET) 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 .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

' 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 Chilkat.BinData
Dim success As Boolean = bdToSend.LoadFile("somePath/someFile.dat")
' Assume success for the example...

Dim sndSock As New Chilkat.Socket
Dim bUseTls As Boolean = True
Dim port As Integer = 5555
Dim maxWaitMs As Integer = 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 Integer = bdToSend.NumBytes
Dim bBigEndian As Boolean = True
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 <> True) Then
    Debug.WriteLine(sndSock.LastErrorText)
    Exit Sub
End If


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


Debug.WriteLine("File sent!")



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

Dim listenSock As New Chilkat.Socket

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


' Get the next incoming connection
' Wait a maximum of 20 seconds (20000 millisec)
Dim rcvSock As Chilkat.Socket
rcvSock = listenSock.AcceptNextConnection(20000)
If (listenSock.LastMethodSuccess = False) Then
    Debug.WriteLine(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 <> True) Then
    Debug.WriteLine(rcvSock.LastErrorText)

    Exit Sub
End If


Dim numBytesComing As Integer = rcvSock.ReceivedInt

' Receive that many bytes..
Dim bdReceived As New Chilkat.BinData
success = rcvSock.ReceiveBdN(numBytesComing,bdReceived)
If (success <> True) Then
    Debug.WriteLine(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 Integer = 20
rcvSock.Close(maxWaitMs)


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


Debug.WriteLine("File received!")