C#

Socket Convert Existing TCP Connection to SSL/TLS

Demonstrates the Chilkat Socket ConvertToSsl method. C#

bool success = false;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

Chilkat.Socket sock = new Chilkat.Socket();

//  --------------------------------------------------------------------
//  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.
bool useTls = true;
int port = 4243;
int maxWaitMs = 5000;
success = sock.Connect("tcpbin.com",port,useTls,maxWaitMs);
if (success == false) {
    Debug.WriteLine(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:
Debug.WriteLine("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) {
    Debug.WriteLine(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) {
    Debug.WriteLine(sock.LastErrorText);
    return;
}

//  OK, we now have a TLS connection.
//  Again, we can see the TLS version:
Debug.WriteLine("TLS version: " + sock.TlsVersion);

sock.Close(maxWaitMs);