congress/congress/api/rule_model.py

206 lines
7.7 KiB
Python

# Copyright (c) 2014 VMware, Inc. All rights reserved.
#
# 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.
#
try:
# For Python 3
import http.client as httplib
except ImportError:
import httplib
import uuid
from congress.api import error_codes
from congress.api import webservice
from congress.db import db_policy_rules
from congress.dse import deepsix
from congress.exception import PolicyException
from congress.openstack.common import log as logging
from congress.policy_engines import agnostic
LOG = logging.getLogger(__name__)
def d6service(name, keys, inbox, datapath, args):
return RuleModel(name, keys, inbox=inbox, dataPath=datapath, **args)
class RuleModel(deepsix.deepSix):
"""Model for handling API requests about policy Rules."""
def __init__(self, name, keys, inbox=None, dataPath=None,
policy_engine=None):
super(RuleModel, self).__init__(name, keys, inbox=inbox,
dataPath=dataPath)
assert policy_engine is not None
self.engine = policy_engine
def policy_name(self, context):
if 'ds_id' in context:
return context['ds_id']
elif 'policy_id' in context:
return context['policy_id']
def get_item(self, id_, params, context=None):
"""Retrieve item with id id_ from model.
Args:
id_: The ID of the item to retrieve
params: A dict-like object containing parameters
from the request query string and body.
context: Key-values providing frame of reference of request
Returns:
The matching item or None if item with id_ does not exist.
"""
policy_name = self.policy_name(context)
rule = db_policy_rules.get_policy_rule(id_, policy_name)
if rule is None:
return
d = {'rule': rule.rule,
'id': rule.id,
'comment': rule.comment,
'name': rule.name}
return d
def get_items(self, params, context=None):
"""Get items in model.
Args:
params: A dict-like object containing parameters
from the request query string and body.
context: Key-values providing frame of reference of request
Returns: A dict containing at least a 'results' key whose value is
a list of items in the model. Additional keys set in the
dict will also be rendered for the user.
"""
policy_name = self.policy_name(context)
rules = db_policy_rules.get_policy_rules(policy_name)
results = []
for rule in rules:
d = {'rule': rule.rule,
'id': rule.id,
'comment': rule.comment,
'name': rule.name}
results.append(d)
return {'results': results}
def add_item(self, item, params, id_=None, context=None):
"""Add item to model.
Args:
item: The item to add to the model
params: A dict-like object containing parameters
from the request query string and body.
id_: The ID of the item, or None if an ID should be generated
context: Key-values providing frame of reference of request
Returns:
Tuple of (ID, newly_created_item)
Raises:
KeyError: ID already exists.
"""
if id_ is not None:
raise webservice.DataModelException(
*error_codes.get('add_item_id'))
# Reject rules inserted into non-persisted policies
# (i.e. datasource policies)
policy_name = self.policy_name(context)
policies = db_policy_rules.get_policies()
persisted_policies = set([p.name for p in policies])
if policy_name not in persisted_policies:
LOG.debug("add_item error: rule not permitted for policy %s",
policy_name)
(num, desc) = error_codes.get('rule_not_permitted')
raise webservice.DataModelException(num, desc)
str_rule = item['rule']
try:
rule = self.engine.parse(str_rule)
if len(rule) == 1:
rule = rule[0]
else:
(num, desc) = error_codes.get('multiple_rules')
raise webservice.DataModelException(
num, desc + ":: Received multiple rules: " +
"; ".join(str(x) for x in rule))
changes = self.change_rule(rule, context)
except PolicyException as e:
LOG.debug("add_item error: invalid rule syntax")
(num, desc) = error_codes.get('rule_syntax')
raise webservice.DataModelException(num, desc + "::" + str(e))
for change in changes:
if change.formula == rule:
d = {'rule': rule.pretty_str(),
'id': str(uuid.uuid4()),
'comment': None,
'name': item.get('name')}
try:
db_policy_rules.add_policy_rule(
d['id'], policy_name, str_rule, d['comment'],
rule_name=d['name'])
return (d['id'], d)
except Exception as db_exception:
try:
self.change_rule(rule, context, insert=False)
except Exception as change_exception:
raise Exception(
"Error thrown during recovery from DB error. "
"Inconsistent state. DB error: %s. "
"New error: %s.", str(db_exception),
str(change_exception))
num, desc = error_codes.get('rule_already_exists')
raise webservice.DataModelException(
num, desc, http_status_code=httplib.CONFLICT)
def delete_item(self, id_, params, context=None):
"""Remove item from model.
Args:
id_: The ID of the item to be removed
params: A dict-like object containing parameters
from the request query string and body.
context: Key-values providing frame of reference of request
Returns:
The removed item.
Raises:
KeyError: Item with specified id_ not present.
"""
item = self.get_item(id_, params, context)
if item is None:
raise KeyError('ID %s does not exist', id_)
rule = self.engine.parse1(item['rule'])
self.change_rule(rule, context, insert=False)
db_policy_rules.delete_policy_rule(id_)
return item
def change_rule(self, parsed_rule, context, insert=True):
policy_name = self.policy_name(context)
if policy_name not in self.engine.theory:
raise KeyError("Policy with ID '%s' does not exist", policy_name)
event = agnostic.Event(
formula=parsed_rule,
insert=insert,
target=policy_name)
(permitted, changes) = self.engine.process_policy_update([event])
if not permitted:
raise PolicyException(
"Errors: " + ";".join((str(x) for x in changes)))
return changes