pop3client.py 文件源码

def startTLS(self, contextFactory=None):
        """
        Initiates a 'STLS' request and negotiates the TLS / SSL
        Handshake.

        @type contextFactory: C{ssl.ClientContextFactory} @param
        contextFactory: The context factory with which to negotiate
        TLS.  If C{None}, try to create a new one.

        @return: A Deferred which fires when the transport has been
        secured according to the given contextFactory, or which fails
        if the transport cannot be secured.
        """
        tls = interfaces.ITLSTransport(self.transport, None)
        if tls is None:
            return defer.fail(TLSError(
                "POP3Client transport does not implement "
                "interfaces.ITLSTransport"))

        if contextFactory is None:
            contextFactory = self._getContextFactory()

        if contextFactory is None:
            return defer.fail(TLSError(
                "POP3Client requires a TLS context to "
                "initiate the STLS handshake"))

        d = self.capabilities()
        d.addCallback(self._startTLS, contextFactory, tls)
        return d