PureBasic

Socket Convert Existing TCP Connection to SSL/TLS

Demonstrates the Chilkat Socket ConvertToSsl method. PureBasic

IncludeFile "CkSocket.pb"

Procedure ChilkatExample()

    success.i = 0

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

    sock.i = CkSocket::ckCreate()
    If sock.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; --------------------------------------------------------------------
    ; 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.
    useTls.i = 1
    port.i = 4243
    maxWaitMs.i = 5000
    success = CkSocket::ckConnect(sock,"tcpbin.com",port,useTls,maxWaitMs)
    If success = 0
        Debug CkSocket::ckLastErrorText(sock)
        CkSocket::ckDispose(sock)
        ProcedureReturn
    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:
    Debug "TLS version: " + CkSocket::ckTlsVersion(sock)

    CkSocket::ckClose(sock,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 0, so we only have a simple TCP connection after this call.
    useTls = 0
    success = CkSocket::ckConnect(sock,"tcpbin.com",port,useTls,maxWaitMs)
    If success = 0
        Debug CkSocket::ckLastErrorText(sock)
        CkSocket::ckDispose(sock)
        ProcedureReturn
    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.)
    success = CkSocket::ckConvertToSsl(sock)
    If success = 0
        Debug CkSocket::ckLastErrorText(sock)
        CkSocket::ckDispose(sock)
        ProcedureReturn
    EndIf

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

    CkSocket::ckClose(sock,maxWaitMs)


    CkSocket::ckDispose(sock)


    ProcedureReturn
EndProcedure