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#!/usr/bin/python2.4
#
# Copyright 2011 Google 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.
#
"""Utility to provide exploration of policy definition files.
Allows read only access of policy definition files. The library
creates a Policy object, which has filters containing terms.
This library does no expansion on the tokens directly, such as in policy.py.
TODO: This library is currently incomplete, and does not allow access to
every argument of a policy term.
"""
__author__ = 'watson@google.com (Tony Watson)'
from capirca import naming
class FileOpenError(Exception):
"""Trouble opening a file."""
class Filter(object):
"""Simple filter with a name a list of terms."""
def __init__(self, filtername=''):
self.name = filtername
self.term = []
def __str__(self):
rval = []
title = 'Filter: %s' % str(self.name)
rval.append('\n%s' % title)
rval.append('-' * len(title))
for term in self.term:
rval.append(str(term))
return '\n\n'.join(rval)
class Term(object):
"""Simple term with a name a list of attributes."""
def __init__(self, termname=''):
self.name = termname
self.source = []
self.destination = []
self.sport = []
self.dport = []
self.action = []
self.option = []
self.protocol = []
def __str__(self):
rval = []
rval.append(' Term: %s' % self.name)
rval.append(' Source-address:: %s' % ' '.join(self.source))
rval.append(' Destination-address:: %s' % ' '.join(self.destination))
rval.append(' Source-port:: %s' % ' '.join(self.sport))
rval.append(' Destination-port:: %s' % ' '.join(self.dport))
rval.append(' Protocol:: %s' % ' '.join(self.protocol))
rval.append(' Option:: %s' % ' '.join(self.option))
rval.append(' Action:: %s' % ' '.join(self.action))
return '\n'.join(rval)
class Policy(object):
"""Holds basic attributes of an unexpanded policy definition file."""
def __init__(self, filename, defs_data=None):
"""Build policy object and naming definitions from provided filenames.
Args:
filename: location of a .pol file
defs_data: location of naming definitions directory, if any
"""
self.defs = naming.Naming(defs_data)
self.filter = []
try:
self.data = open(filename, 'r').readlines()
except IOError, error_info:
info = str(filename) + ' cannot be opened'
raise FileOpenError('%s\n%s' % (info, error_info))
indent = 0
in_header = False
in_term = False
filt = Filter()
term = Term()
in_string = False
for line in self.data:
words = line.strip().split()
quotes = len(line.split('"')) + 1
if quotes % 2: # are we in or out of double quotes
in_string = not in_string # flip status of quote status
if not in_string:
if '{' in words:
indent += 1
if words:
if words[0] == 'header':
in_header = True
if words[0] == 'term':
in_term = True
term = Term(words[1])
if in_header and words[0] == 'target::':
if filt.name != words[2]: # avoid empty dupe filters due to
filt = Filter(words[2]) # multiple target header lines
if in_term:
if words[0] == 'source-address::':
term.source.extend(words[1:])
if words[0] == 'destination-address::':
term.destination.extend(words[1:])
if words[0] == 'source-port::':
term.sport.extend(words[1:])
if words[0] == 'destination-port::':
term.dport.extend(words[1:])
if words[0] == 'action::':
term.action.extend(words[1:])
if words[0] == 'protocol::':
term.protocol.extend(words[1:])
if words[0] == 'option::':
term.option.extend(words[1:])
if '}' in words:
indent -= 1
if in_header:
self.filter.append(filt)
in_header = False
if in_term:
filt.term.append(term)
in_term = False
def __str__(self):
return '\n'.join(str(next) for next in self.filter)
def Matches(self, src=None, dst=None, dport=None, sport=None,
filtername=None):
"""Return list of term names that match specific attributes.
Args:
src: source ip address '12.1.1.1'
dst: destination ip address '10.1.1.1'
dport: any port/protocol combo, such as '80/tcp' or '53/udp'
sport: any port/protocol combo, such as '80/tcp' or '53/udp'
filtername: a filter name or None to search all filters
Returns:
results: list of lists, each list is index to filter & term in the policy
Example:
p=policyreader.Policy('policy_path', 'definitions_path')
p.Matches(dst='209.85.216.5', dport='25/tcp')
[[0, 26]]
print p.filter[0].term[26].name
for match in p.Matches(dst='209.85.216.5'):
print p.filter[match[0]].term[match[1]].name
"""
rval = []
results = []
filter_list = []
dport_parents = None
sport_parents = None
destination_parents = None
source_parents = None
if dport:
dport_parents = self.defs.GetServiceParents(dport)
if sport:
sport_parents = self.defs.GetServiceParents(sport)
if dst:
destination_parents = self.defs.GetIpParents(dst)
try:
destination_parents.remove('ANY')
destination_parents.remove('RESERVED')
except ValueError:
pass # ignore and continue
if src:
source_parents = self.defs.GetIpParents(src)
try:
source_parents.remove('ANY')
source_parents.remove('RESERVED')
except ValueError:
pass # ignore and continue
if not filtername:
filter_list = self.filter
else:
for idx, next in enumerate(self.filter):
if filtername == next.name:
filter_list = [self.filter[idx]]
if not filter_list:
raise 'invalid filter name: %s' % filtername
for findex, xfilter in enumerate(filter_list):
mterms = []
mterms.append(set()) # dport
mterms.append(set()) # sport
mterms.append(set()) # dst
mterms.append(set()) # src
for tindex, term in enumerate(xfilter.term):
if dport_parents:
for token in dport_parents:
if token in term.dport:
mterms[0].add(tindex)
else:
mterms[0].add(tindex)
if sport_parents:
for token in sport_parents:
if token in term.sport:
mterms[1].add(tindex)
else:
mterms[1].add(tindex)
if destination_parents:
for token in destination_parents:
if token in term.destination:
mterms[2].add(tindex)
else:
mterms[2].add(tindex)
if source_parents:
for token in source_parents:
if token in term.source:
mterms[3].add(tindex)
else:
mterms[3].add(tindex)
rval.append(list(mterms[0] & mterms[1] & mterms[2] & mterms[3]))
for findex, fresult in enumerate(rval):
for next in list(fresult):
results.append([findex, next])
return results
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