PureBasic

Upgrade a Plain TCP Connection to TLS

Demonstrates Socket.ConvertToSsl, which upgrades an already-connected plain TCP socket to TLS by performing a client-side TLS handshake over the existing connection.

Background. This supports STARTTLS-style upgrades, where a protocol begins in plaintext and switches to TLS at a defined point. Perform the protocol-specific negotiation first, then call ConvertToSsl.

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PureBasic

IncludeFile "CkSocket.pb"

Procedure ChilkatExample()

    success.i = 0

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

    ;  Connect as plain TCP (no TLS yet).
    bTls.i = 0
    maxWaitMs.i = 5000
    success = CkSocket::ckConnect(socket,"example.com",5000,bTls,maxWaitMs)
    If success = 0
        Debug CkSocket::ckLastErrorText(socket)
        CkSocket::ckDispose(socket)
        ProcedureReturn
    EndIf

    ;  At the point where the application protocol permits a STARTTLS-style upgrade, perform any required
    ;  negotiation, then upgrade the existing connection to TLS with a client-side handshake.
    success = CkSocket::ckConvertToSsl(socket)
    If success = 0
        Debug CkSocket::ckLastErrorText(socket)
        CkSocket::ckDispose(socket)
        ProcedureReturn
    EndIf

    Debug "Connection upgraded to TLS."


    CkSocket::ckDispose(socket)


    ProcedureReturn
EndProcedure