B4X

Socket Convert Existing TCP Connection to SSL/TLS

Demonstrates the Chilkat Socket ConvertToSsl method. B4X

Dim success As Boolean = False

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

Dim sock As ChilkatSocket
sock.Initialize("sock")

'  --------------------------------------------------------------------
'  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.
Dim useTls As Boolean = True
Dim port As Int = 4243
Dim maxWaitMs As Int = 5000
success = sock.Connect("tcpbin.com", port, useTls, maxWaitMs)
If success = False Then
    Log(sock.LastErrorText)
    Return
End If


'  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:
Log("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 Then
    Log(sock.LastErrorText)
    Return
End If


'  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 Then
    Log(sock.LastErrorText)
    Return
End If


'  OK, we now have a TLS connection.
'  Again, we can see the TLS version:
Log("TLS version: " & sock.TlsVersion)

sock.Close(maxWaitMs)