(Java) Accept TLS Connection with Client Authentication

Demonstrates how to accept a TLS connection requiring client authentication. This is the case where the TLS client sends a certificate. It is also known as "Two-Way SSL".

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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 listenSslSocket = new CkSocket();

    // An SSL/TLS server needs a digital certificate.  This example loads it from a PFX file.
    // Note: This is the server's certificate.

    CkCert cert = new CkCert();
    // The 1st argument is the file path, the 2nd arg is the 
    // PFX file's password:
    boolean success = cert.LoadPfxFile("chilkat.pfx","test");
    if (success != true) {
        System.out.println(cert.lastErrorText());
        return;
        }

    // To accept client client certificates in the TLS handshake,
    // we must indicate a list of acceptable client certificate root CA DN's
    // that are allowed.  (DN is an acronym for Distinguished Name.)
    // Call AddSslAcceptableClientCaDn once for each acceptable CA DN.
    // Here are a few examples so you can see the general format of a DN.
    listenSslSocket.AddSslAcceptableClientCaDn("C=SE, O=AddTrust AB, OU=AddTrust External TTP Network, CN=AddTrust External CA Root");
    listenSslSocket.AddSslAcceptableClientCaDn("O=Digital Signature Trust Co., CN=DST Root CA X3");

    // Use the certificate:
    success = listenSslSocket.InitSslServer(cert);
    if (success != true) {
        System.out.println(listenSslSocket.lastErrorText());
        return;
        }

    // Bind and listen on a port:
    int myPort = 8123;
    // Allow for a max of 5 queued connect requests.
    int backLog = 5;
    success = listenSslSocket.BindAndListen(myPort,backLog);
    if (success != true) {
        System.out.println(listenSslSocket.lastErrorText());
        return;
        }

    // If accepting an SSL/TLS connection, the SSL handshake is part of the connection
    // establishment process. This involves a few back-and-forth messages between the 
    // client and server to establish algorithms and a shared key to create the secure 
    // channel. The sending and receiving of these messages are governed by the 
    // MaxReadIdleMs and MaxSendIdleMs properties. If these properties are set to 0 
    // (and this is the default unless changed by your application), then the 
    // AcceptNextConnection can hang indefinitely during the SSL handshake process. 
    // Make sure these properties are set to appropriate values before calling AcceptNextConnection.

    // Set a 10 second max for waiting to read/write.  This is for the SSL/TLS handshake establishment.
    listenSslSocket.put_MaxReadIdleMs(10000);
    listenSslSocket.put_MaxSendIdleMs(10000);

    // Accept a single client connection and establish the secure SSL/TLS channel:
    CkSocket clientSock;
    int maxWaitMillisec = 20000;
    clientSock = listenSslSocket.AcceptNextConnection(maxWaitMillisec);
    if (listenSslSocket.get_LastMethodSuccess() == false) {
        System.out.println(listenSslSocket.lastErrorText());
        return;
        }

    // The client (in this example) is going to send a "Hello Server! -EOM-" 
    // message.  Read it:
    String receivedMsg = clientSock.receiveUntilMatch("-EOM-");
    if (clientSock.get_LastMethodSuccess() != true) {
        System.out.println(clientSock.lastErrorText());
        return;
        }

    System.out.println(receivedMsg);

    // Send a "Hello Client! -EOM-" message:
    success = clientSock.SendString("Hello Client! -EOM-");
    if (success != true) {
        System.out.println(clientSock.lastErrorText());
        return;
        }

    // Close the connection with the client
    // Wait a max of 20 seconds (20000 millsec)
    success = clientSock.Close(20000);
  }
}