(Java) Socket Convert Existing TCP Connection to SSL/TLS

Demonstrates the Chilkat Socket ConvertToSsl method.

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkSocket sock = new CkSocket();

    // --------------------------------------------------------------------
    // This example uses the public TCP/TLS echo service at https://tcpbin.com/
    // --------------------------------------------------------------------

    // The echo server at tcpbin.com expects to receive TCP connections on port 4242, and TLS connections on port 4243.
    // We could simply connect to port 4243 using TLS like this.
    // However, further below, this example shows how to initially make a TCP connection, and then convert the connection to TLS.
    boolean useTls = true;
    int port = 4243;
    int maxWaitMs = 5000;
    boolean success = sock.Connect("tcpbin.com",port,useTls,maxWaitMs);
    if (success == false) {
        System.out.println(sock.lastErrorText());
        return;
        }

    // OK, we have a TLS connection.
    // Note: The server chooses the TLS protocol version. 
    // We can see the version of the TLS connection that was established:
    System.out.println("TLS version: " + sock.tlsVersion());

    sock.Close(maxWaitMs);

    // ---------------------------------------------------------------------
    // Now we'll do the same, except first we connect to port 4243 using TCP,
    // and then convert the connection to TLS.
    // 
    // This may seem pointless, and it is for the case w/ this server.  However, there could be situations
    // where you're interacting with a server of some kind where there is a need to convert to/from TLS.
    // (This is common internal to many protocols, such as SMTP, IMAP, FTP, etc., and it is often called "explicit" SSL/TLS)

    // Connect again, except this time useTls is false, so we only have a simple TCP connection after this call.
    useTls = false;
    success = sock.Connect("tcpbin.com",port,useTls,maxWaitMs);
    if (success == false) {
        System.out.println(sock.lastErrorText());
        return;
        }

    // Convert the existing TCP connection to TLS.
    // (The method name uses "SSL" because long ago, at the time of initial development, TLS 1.0 did not yet exist.)
    success = sock.ConvertToSsl();
    if (success == false) {
        System.out.println(sock.lastErrorText());
        return;
        }

    // OK, we now have a TLS connection.
    // Again, we can see the TLS version:
    System.out.println("TLS version: " + sock.tlsVersion());

    sock.Close(maxWaitMs);
  }
}