OpenFlow errors

In OpenFaucet, OpenFlow OFPT_ERROR error messages are represented as exceptions of type OpenflowError. In a message handler, sending an error message to the peer is done by raising an OpenflowError exception, with the appropriate error type, error code, and data to describe the error. For instance, in an OpenFlow controller’s handle_port_status() callback:

from openfaucet import oferror

class MyController(object):

    def handle_port_status(self, reason, desc):
        # ...
        raise oferror.OpenflowError(oferror.OFPET_BAD_REQUEST,
                                    oferror.OFPBRC_EPERM, ())

The exception object is transparently catched and serialized by an OpenFaucet IOpenflowControllerStub protocol object into an OFPT_ERROR OpenFlow message.

class openfaucet.oferror.OpenflowError

__init__(error_type, error_code, data)

Create an OpenflowError.

Parameters:

• error_type – The error type, as one of the OFPET_* constants.
• error_code – The error code, as one of the OFP* error code constants.
• data – The data attached in the error message, as a sequence of binary strings.

A standard set of valid error types is defined in the OpenFlow standard, as well as a set of valid error codes for every error type. Most error types and codes can only be sent by a datapath to a controller.

openfaucet.oferror.OFPET_HELLO_FAILED

The hello protocol failed. This error can be raised only when handling an OFPT_HELLO message during the initial handshake.

openfaucet.oferror.OFPHFC_INCOMPATIBLE

The peers use incompatible versions of the protocol.

openfaucet.oferror.OFPHFC_EPERM

Permissions error.

openfaucet.oferror.OFPET_BAD_REQUEST

The request was not understood.

openfaucet.oferror.OFPBRC_BAD_VERSION

The protocol version in the received message is not supported.

openfaucet.oferror.OFPBRC_BAD_TYPE

The message type is not supported.

openfaucet.oferror.OFPBRC_BAD_STAT

The stats type is not supported.

openfaucet.oferror.OFPBRC_BAD_VENDOR

The received vendor ID is not supported.

openfaucet.oferror.OFPBRC_BAD_SUBTYPE

The received vendor-specific subtype is not supported.

openfaucet.oferror.OFPBRC_EPERM

Permissions error.

openfaucet.oferror.OFPBRC_BAD_LEN

The message has an invalid length.

openfaucet.oferror.OFPBRC_BUFFER_EMPTY

The specified buffer has already been used.

openfaucet.oferror.OFPBRC_BUFFER_UNKNOWN

The specified buffer does not exist.

openfaucet.oferror.OFPET_BAD_ACTION

Error in an action description.

openfaucet.oferror.OFPBAC_BAD_TYPE

Unknown action type.

openfaucet.oferror.OFPBAC_BAD_LEN

An action has an invalid length.

openfaucet.oferror.OFPBAC_BAD_VENDOR

A vendor action has a vendor ID that is unsupported.

openfaucet.oferror.OFPBAC_BAD_VENDOR_TYPE

A vendor action has a vendor-specific subtype that is not supported.

openfaucet.oferror.OFPBAC_BAD_OUT_PORT

An output action has an invalid port number.

openfaucet.oferror.OFPBAC_BAD_ARGUMENT

An action has an invalid argument.

openfaucet.oferror.OFPBAC_EPERM

Permissions error.

openfaucet.oferror.OFPBAC_TOO_MANY

Can’t handle this many actions.

openfaucet.oferror.OFPBAC_BAD_QUEUE

An action has an invalid queue number argument.

openfaucet.oferror.OFPET_FLOW_MOD_FAILED

Problem when modifying a flow entry.

openfaucet.oferror.OFPFMFC_ALL_TABLES_FULL

The flow cannot be added because of full tables.

openfaucet.oferror.OFPFMFC_OVERLAP

Attempted to add an overlapping flow with check_overlap set to True.

openfaucet.oferror.OFPFMFC_EPERM

Permissions error.

openfaucet.oferror.OFPFMFC_BAD_EMERG_TIMEOUT

The flow cannot added because emerg was set to True and the idle and hard timeouts were set to non-zero.

openfaucet.oferror.OFPFMFC_BAD_COMMAND

An OFPT_FLOW_MOD message was sent with an invalid command.

openfaucet.oferror.OFPFMFC_UNSUPPORTED

The specified list of actions cannot be processed in this order.

openfaucet.oferror.OFPET_PORT_MOD_FAILED

A port modification request failed.

openfaucet.oferror.OFPPMFC_BAD_PORT

The specified port number does not exist.

openfaucet.oferror.OFPPMFC_BAD_HW_ADDR

The specified port hardware address is wrong.

openfaucet.oferror.OFPET_QUEUE_OP_FAILED

A queue operation failed.

openfaucet.oferror.OFPQOFC_BAD_PORT

The specified port number does not exist or is invalid.

openfaucet.oferror.OFPQOFC_BAD_QUEUE

The specified queue number does not exist.

openfaucet.oferror.OFPQOFC_EPERM

Permissions error.

The semantics of data in an OpenflowError depends on the error type. For OFPET_HELLO_FAILED errors, data is an ASCII text string that adds detail on why the error occurred:

from openfaucet import oferror

raise oferror.OpenflowError(oferror.OFPET_HELLO_FAILED,
                            oferror.OFPHFC_INCOMPATIBLE,
                            ('only v1.0.0 supported',))

For all other error types, data contains at least 64 bytes of the failed request. raise_error_with_request() is a helper method of protocol objects that can be used to raise exceptions with such data, for instance in a controller callback:

from openfaucet import oferror

class MyController(object):

    def connection_made(self):
        # ...
        self.protocol().raise_error_with_request(oferror.OFPET_HELLO_FAILED,
                                                 oferror.OFPHFC_EPERM)