(MFC) 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 C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkBinData.h>
#include <CkSocket.h>

void ChilkatSample(void)
    {
    CkString strOut;

    // 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.
    CkBinData bdToSend;
    bool success = bdToSend.LoadFile("somePath/someFile.dat");
    // Assume success for the example...

    CkSocket sndSock;
    bool bUseTls = true;
    int port = 5555;
    int 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.
    int numBytes = bdToSend.get_NumBytes();
    bool bBigEndian = 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) {
        strOut.append(sndSock.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Did the receiver get the correct number of bytes?
    if (sndSock.get_ReceivedInt() != numBytes) {
        strOut.append("The receiver did not acknowledge with the correct number of bytes.");
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    strOut.append("File sent!");
    strOut.append("\r\n");

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

    CkSocket listenSock;

    success = listenSock.BindAndListen(5555,25);
    if (success != true) {
        strOut.append(listenSock.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Get the next incoming connection
    // Wait a maximum of 20 seconds (20000 millisec)
    CkSocket *rcvSock = 0;
    rcvSock = listenSock.AcceptNextConnection(20000);
    if (listenSock.get_LastMethodSuccess() == false) {
        strOut.append(listenSock.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // The sender will first send the big-endian integer for the number of bytes
    // that are forthcoming..
    success = rcvSock->ReceiveInt32(bBigEndian);
    if (success != true) {
        strOut.append(rcvSock->lastErrorText());
        strOut.append("\r\n");
        delete rcvSock;
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    int numBytesComing = rcvSock->get_ReceivedInt();

    // Receive that many bytes..
    CkBinData bdReceived;
    success = rcvSock->ReceiveBdN(numBytesComing,bdReceived);
    if (success != true) {
        strOut.append(rcvSock->lastErrorText());
        strOut.append("\r\n");
        delete rcvSock;
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Acknowledge the sender by sending back the number of bytes we received.
    success = rcvSock->SendInt32(bdReceived.get_NumBytes(),bBigEndian);

    // Close the connection.
    int maxWaitMs = 20;
    rcvSock->Close(maxWaitMs);
    delete rcvSock;

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

    strOut.append("File received!");
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }