path: root/src/ovs/ofctl.py

# Copyright 2015 Intel Corporation.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Wrapper for an OVS bridge for convenient use of ``ovs-vsctl`` and
``ovs-ofctl`` on it.

Much of this code is based on ``ovs-lib.py`` from Open Stack:

https://github.com/openstack/neutron/blob/6eac1dc99124ca024d6a69b3abfa3bc69c735667/neutron/agent/linux/ovs_lib.py
"""

import os
import logging
import string

from tools import tasks
from conf import settings

_OVS_VSCTL_BIN = os.path.join(settings.getValue('OVS_DIR'), 'utilities',
                              'ovs-vsctl')
_OVS_OFCTL_BIN = os.path.join(settings.getValue('OVS_DIR'), 'utilities',
                              'ovs-ofctl')

class OFBase(object):
    """Add/remove/show datapaths using ``ovs-ofctl``.
    """
    def __init__(self, timeout=10):
        """Initialise logger.

        :param timeout: Timeout to be used for each command

        :returns: None
        """
        self.logger = logging.getLogger(__name__)
        self.timeout = timeout

    # helpers

    def run_vsctl(self, args, check_error=False):
        """Run ``ovs-vsctl`` with supplied arguments.

        :param args: Arguments to pass to ``ovs-vsctl``
        :param check_error: Throw exception on error

        :return: None
        """
        cmd = ['sudo', _OVS_VSCTL_BIN, '--timeout', str(self.timeout)] + args
        return tasks.run_task(
            cmd, self.logger, 'Running ovs-vsctl...', check_error)

    # datapath management

    def add_br(self, br_name='br0'):
        """Add datapath.

        :param br_name: Name of bridge

        :return: Instance of :class OFBridge:
        """
        self.logger.debug('add bridge')
        self.run_vsctl(['add-br', br_name])

        return OFBridge(br_name, self.timeout)

    def del_br(self, br_name='br0'):
        """Delete datapath.

        :param br_name: Name of bridge

        :return: None
        """
        self.logger.debug('delete bridge')
        self.run_vsctl(['del-br', br_name])


class OFBridge(OFBase):
    """Control a bridge instance using ``ovs-vsctl`` and ``ovs-ofctl``.
    """
    def __init__(self, br_name='br0', timeout=10):
        """Initialise bridge.

        :param br_name: Bridge name
        :param timeout: Timeout to be used for each command

        :returns: None
        """
        super(OFBridge, self).__init__(timeout)
        self.br_name = br_name
        self._ports = {}

    # context manager

    def __enter__(self):
        """Create datapath

        :returns: self
        """
        return self

    def __exit__(self, type_, value, traceback):
        """Remove datapath.
        """
        if not traceback:
            self.destroy()

    # helpers

    def run_ofctl(self, args, check_error=False):
        """Run ``ovs-ofctl`` with supplied arguments.

        :param args: Arguments to pass to ``ovs-ofctl``
        :param check_error: Throw exception on error

        :return: None
        """
        cmd = ['sudo', _OVS_OFCTL_BIN, '--timeout', str(self.timeout)] + args
        return tasks.run_task(
            cmd, self.logger, 'Running ovs-ofctl...', check_error)

    def create(self):
        """Create bridge.
        """
        self.logger.debug('create bridge')
        self.add_br(self.br_name)

    def destroy(self):
        """Destroy bridge.
        """
        self.logger.debug('destroy bridge')
        self.del_br(self.br_name)

    def reset(self):
        """Reset bridge.
        """
        self.logger.debug('reset bridge')
        self.destroy()
        self.create()

    # port management

    def add_port(self, port_name, params):
        """Add port to bridge.

        :param port_name: Name of port
        :param params: Additional list of parameters to add-port

        :return: OpenFlow port number for the port
        """
        self.logger.debug('add port')
        self.run_vsctl(['add-port', self.br_name, port_name]+params)

        # This is how port number allocation works currently
        # This possibly will not work correctly if there are port deletions
        # in between
        of_port = len(self._ports) + 1
        self._ports[port_name] = (of_port, params)
        return of_port

    def del_port(self, port_name):
        """Remove port from bridge.

        :param port_name: Name of port

        :return: None
        """
        self.logger.debug('delete port')
        self.run_vsctl(['del-port', self.br_name, port_name])
        self._ports.pop(port_name)

    def set_db_attribute(self, table_name, record, column, value):
        """Set database attribute.

        :param table_name: Name of table
        :param record: Name of record
        :param column: Name of column
        :param value: Value to set

        :return: None
        """
        self.logger.debug('set attribute')
        self.run_vsctl(['set', table_name, record, '%s=%s' % (column, value)])

    def get_ports(self):
        """Get the ports of this bridge

        Structure of the returned ports dictionary is
        'portname': (openflow_port_number, extra_parameters)

        Example:
        ports = {
            'dpdkport0':
                (1, ['--', 'set', 'Interface', 'dpdkport0', 'type=dpdk']),
            'dpdkvhostport0':
                (2, ['--', 'set', 'Interface', 'dpdkvhostport0',
                     'type=dpdkvhost'])
        }

        :return: Dictionary of ports
        """
        return self._ports

    def clear_db_attribute(self, table_name, record, column):
        """Clear database attribute.

        :param table_name: Name of table
        :param record: Name of record
        :param column: Name of column

        :return: None
        """
        self.logger.debug('clear attribute')
        self.run_vsctl(['clear', table_name, record, column])

    # flow mangement

    def add_flow(self, flow):
        """Add flow to bridge.

        :param flow: Flow description as a dictionary
        For flow dictionary structure, see function flow_key

        :return: None
        """
        if not flow.get('actions'):
            self.logger.error('add flow requires actions')
            return

        self.logger.debug('add flow')
        _flow_key = flow_key(flow)
        self.logger.debug('key : %s', _flow_key)
        self.run_ofctl(['add-flow', self.br_name, _flow_key])

    def del_flow(self, flow):
        """Delete flow from bridge.

        :param flow: Flow description as a dictionary
        For flow dictionary structure, see function flow_key
        flow=None will delete all flows

        :return: None
        """
        self.logger.debug('delete flow')
        _flow_key = flow_key(flow)
        self.logger.debug('key : %s', _flow_key)
        self.run_ofctl(['del-flows', self.br_name, _flow_key])

    def del_flows(self):
        """Delete all flows from bridge.
        """
        self.logger.debug('delete flows')
        self.run_ofctl(['del-flows', self.br_name])

    def dump_flows(self):
        """Dump all flows from bridge.
        """
        self.logger.debug('dump flows')
        self.run_ofctl(['dump-flows', self.br_name])

#
# helper functions
#

def flow_key(flow):
    """Model a flow key string for ``ovs-ofctl``.

    Syntax taken from ``ovs-ofctl`` manpages:
        http://openvswitch.org/cgi-bin/ovsman.cgi?page=utilities%2Fovs-ofctl.8

    Example flow dictionary:
    flow = {
        'in_port': '1',
        'idle_timeout': '0',
        'actions': ['output:3']
    }

    :param flow: Flow description as a dictionary

    :return: String
    :rtype: str
    """
    _flow_add_key = string.Template('${fields},action=${actions}')
    _flow_del_key = string.Template('${fields}')

    field_params = []

    user_params = (x for x in list(flow.items()) if x[0] != 'actions')
    for (key, default) in user_params:
        field_params.append('%(field)s=%(value)s' %
                            {'field': key, 'value': default})

    field_params = ','.join(field_params)

    _flow_key_param = {
        'fields': field_params,
    }

    # no actions == delete key
    if 'actions' in flow:
        _flow_key_param['actions'] = ','.join(flow['actions'])

        flow_str = _flow_add_key.substitute(_flow_key_param)
    else:
        flow_str = _flow_del_key.substitute(_flow_key_param)

    return flow_str