(Lianja) 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.

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// 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.
loBdToSend = createobject("CkBinData")
llSuccess = loBdToSend.LoadFile("somePath/someFile.dat")
// Assume success for the example...

loSndSock = createobject("CkSocket")
llBUseTls = .T.
lnPort = 5555
lnMaxWaitMs = 5000
llSuccess = loSndSock.Connect("some_domain_or_ip.com",lnPort,llBUseTls,lnMaxWaitMs)
// Assume success for the example...

// Tell the receiver how many bytes are coming.
lnNumBytes = loBdToSend.NumBytes
llBBigEndian = .T.
llSuccess = loSndSock.SendInt32(lnNumBytes,llBBigEndian)

// Send the file data (sends the entire contents of bdToSend).
llSuccess = loSndSock.SendBd(loBdToSend,0,0)

// Get an acknowledgement.
llSuccess = loSndSock.ReceiveInt32(llBBigEndian)
if (llSuccess <> .T.) then
    ? loSndSock.LastErrorText
    release loBdToSend
    release loSndSock
    return
endif

// Did the receiver get the correct number of bytes?
if (loSndSock.ReceivedInt <> lnNumBytes) then
    ? "The receiver did not acknowledge with the correct number of bytes."
    release loBdToSend
    release loSndSock
    return
endif

? "File sent!"

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

loListenSock = createobject("CkSocket")

llSuccess = loListenSock.BindAndListen(5555,25)
if (llSuccess <> .T.) then
    ? loListenSock.LastErrorText
    release loBdToSend
    release loSndSock
    release loListenSock
    return
endif

// Get the next incoming connection
// Wait a maximum of 20 seconds (20000 millisec)

loRcvSock = loListenSock.AcceptNextConnection(20000)
if (loListenSock.LastMethodSuccess = .F.) then
    ? loListenSock.LastErrorText
    release loBdToSend
    release loSndSock
    release loListenSock
    return
endif

// The sender will first send the big-endian integer for the number of bytes
// that are forthcoming..
llSuccess = loRcvSock.ReceiveInt32(llBBigEndian)
if (llSuccess <> .T.) then
    ? loRcvSock.LastErrorText
    release loRcvSock
    release loBdToSend
    release loSndSock
    release loListenSock
    return
endif

lnNumBytesComing = loRcvSock.ReceivedInt

// Receive that many bytes..
loBdReceived = createobject("CkBinData")
llSuccess = loRcvSock.ReceiveBdN(lnNumBytesComing,loBdReceived)
if (llSuccess <> .T.) then
    ? loRcvSock.LastErrorText
    release loRcvSock
    release loBdToSend
    release loSndSock
    release loListenSock
    release loBdReceived
    return
endif

// Acknowledge the sender by sending back the number of bytes we received.
llSuccess = loRcvSock.SendInt32(loBdReceived.NumBytes,llBBigEndian)

// Close the connection.
lnMaxWaitMs = 20
loRcvSock.Close(lnMaxWaitMs)
release loRcvSock

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

? "File received!"


release loBdToSend
release loSndSock
release loListenSock
release loBdReceived