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

Demonstrates the Chilkat Socket ConvertToSsl method.

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

loSock = createobject("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.
llUseTls = .T.
lnPort = 4243
lnMaxWaitMs = 5000
llSuccess = loSock.Connect("tcpbin.com",lnPort,llUseTls,lnMaxWaitMs)
if (llSuccess = .F.) then
    ? loSock.LastErrorText
    release loSock
    return
endif

// 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:
? "TLS version: " + loSock.TlsVersion

loSock.Close(lnMaxWaitMs)

// ---------------------------------------------------------------------
// 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 .F., so we only have a simple TCP connection after this call.
llUseTls = .F.
llSuccess = loSock.Connect("tcpbin.com",lnPort,llUseTls,lnMaxWaitMs)
if (llSuccess = .F.) then
    ? loSock.LastErrorText
    release loSock
    return
endif

// 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.)
llSuccess = loSock.ConvertToSsl()
if (llSuccess = .F.) then
    ? loSock.LastErrorText
    release loSock
    return
endif

// OK, we now have a TLS connection.
// Again, we can see the TLS version:
? "TLS version: " + loSock.TlsVersion

loSock.Close(lnMaxWaitMs)


release loSock