imaplib.py 文件源码

def starttls(self, ssl_context=None):
        name = 'STARTTLS'
        if not HAVE_SSL:
            raise self.error('SSL support missing')
        if self._tls_established:
            raise self.abort('TLS session already established')
        if name not in self.capabilities:
            raise self.abort('TLS not supported by server')
        # Generate a default SSL context if none was passed.
        if ssl_context is None:
            ssl_context = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
            # SSLv2 considered harmful.
            ssl_context.options |= ssl.OP_NO_SSLv2
        typ, dat = self._simple_command(name)
        if typ == 'OK':
            self.sock = ssl_context.wrap_socket(self.sock)
            self.file = self.sock.makefile('rb')
            self._tls_established = True
            self._get_capabilities()
        else:
            raise self.error("Couldn't establish TLS session")
        return self._untagged_response(typ, dat, name)