def connect()

in libcloud/compute/ssh.py [0:0]
61 lines of code
23 McCabe index (conditional complexity)

    def connect(self):
        conninfo = {
            "hostname": self.hostname,
            "port": self.port,
            "username": self.username,
            "allow_agent": False,
            "look_for_keys": False,
        }

        if self.password:
            conninfo["password"] = self.password

        if self.key_files:
            conninfo["key_filename"] = self.key_files

        if self.key_material:
            conninfo["pkey"] = self._get_pkey_object(key=self.key_material, password=self.password)

        if not self.password and not (self.key_files or self.key_material):
            conninfo["allow_agent"] = True
            conninfo["look_for_keys"] = True

        if self.timeout:
            conninfo["timeout"] = self.timeout

        # This is a workaround for paramiko only supporting key files in
        # format staring with "BEGIN RSA PRIVATE KEY".
        # If key_files are provided and a key looks like a PEM formatted key
        # we try to convert it into a format supported by paramiko
        if (
            self.key_files
            and not isinstance(self.key_files, (list, tuple))
            and os.path.isfile(self.key_files)
        ):
            with open(self.key_files) as fp:
                key_material = fp.read()

            try:
                pkey = self._get_pkey_object(key=key_material, password=self.password)
            except paramiko.ssh_exception.PasswordRequiredException as e:
                raise e
            except Exception:
                pass
            else:
                # It appears key is valid, but it was passed in in an invalid
                # format. Try to use the converted key directly
                del conninfo["key_filename"]
                conninfo["pkey"] = pkey

        extra = {
            "_hostname": self.hostname,
            "_port": self.port,
            "_username": self.username,
            "_timeout": self.timeout,
        }

        if self.password:
            extra["_auth_method"] = "password"
        else:
            extra["_auth_method"] = "key_file"

            if self.key_files:
                extra["_key_file"] = self.key_files

        self.logger.debug("Connecting to server", extra=extra)

        try:
            self.client.connect(**conninfo)
        except paramiko.ssh_exception.AuthenticationException as e:
            # Special case to handle paramiko >= 2.9.0 which supports SHA-2
            # variants of the RSA key verification algorithm which don't work
            # with older OpenSSH server versions (e.g. default setup on Ubuntu
            # 14.04).
            # Sadly there is no way for us to catch and retry on more specific
            # / granular exception.
            # See https://www.paramiko.org/changelog.html for details.
            if (
                PARAMIKO_VERSION_TUPLE >= (2, 9, 0)
                and LIBCLOUD_PARAMIKO_SHA2_BACKWARD_COMPATIBILITY
            ):
                self.logger.warn(SHA2_PUBKEY_NOT_SUPPORTED_AUTH_ERROR_MSG)

                conninfo["disabled_algorithms"] = {"pubkeys": ["rsa-sha2-256", "rsa-sha2-512"]}
                self.client.connect(**conninfo)
            else:
                raise e

        return True