Source code for mentat.services.dnsr

# -*- coding: utf-8 -*-
#-------------------------------------------------------------------------------
# This file is part of Mentat system (https://mentat.cesnet.cz/).
#
# Copyright (C) since 2011 CESNET, z.s.p.o (http://www.ces.net/)
# Use of this source is governed by the MIT license, see LICENSE file.
#-------------------------------------------------------------------------------


"""
Implementation of internal **DNS** service library.
"""


__author__ = "Jan Mach <jan.mach@cesnet.cz>"
__credits__ = "Pavel Kácha <pavel.kacha@cesnet.cz>, Andrea Kropáčová <andrea.kropacova@cesnet.cz>"


import copy
import dns.resolver
import dns.exception
import ipranges

from mentat.const import CKEY_CORE_SERVICES, CKEY_CORE_SERVICES_DNS


_MANAGER = None


[docs]class DnsService: """ Implementation of internal **DNS** database service. """ def __init__(self, timeout = 1, lifetime = 3): """ Initialize geolocation service with paths to desired database files. """ self.resolver = None self.timeout = timeout self.lifetime = lifetime
[docs] def setup(self): """ Setup internal DNS service resolver. """ self.resolver = dns.resolver.Resolver() self.resolver.timeout = self.timeout self.resolver.lifetime = self.lifetime
[docs] def status(self): """ Display status of internal geolocation readers. """ return { 'timeout': self.timeout, 'lifetime': self.lifetime }
[docs] def lookup_ip(self, ipaddr): """ Lookup given IP address in DNS. """ result = [] revipaddr = dns.reversename.from_address(ipaddr) # create .in-addr.arpa address try: answer = self.resolver.query(revipaddr, "PTR") for res in answer.rrset: res = str(res) if res[-1] == '.': res = res[:-1] # trim trailing '.' result.append({'type': 'PTR', 'value': res}) except dns.exception.Timeout as exc: raise RuntimeError("DNS query for {} timed out".format(ipaddr)) except dns.exception.DNSException as exc: pass return result
[docs] def lookup_hostname(self, hname): """ Lookup given hostname in DNS. """ result = [] try: for qtype in ('A', 'AAAA'): answer = self.resolver.query(hname, qtype) for res in answer.rrset: res = str(res) result.append({'type': qtype, 'value': res}) except dns.exception.Timeout as exc: raise RuntimeError("DNS query for {} timed out".format(hname)) except dns.exception.DNSException as exc: pass return result
[docs] def lookup(self, thing): """ Lookup given object in DNS. """ for tconv in ipranges.IP4, ipranges.IP6: try: tconv(thing) return self.lookup_ip(thing) except ValueError: pass return self.lookup_hostname(thing)
[docs]class DnsServiceManager: """ Class representing a custom DnsServiceManager capable of understanding and parsing Mentat system core configurations and enabling easy way of unified bootstrapping of :py:class:`mentat.services.dns.DnsService` service. """ def __init__(self, core_config, updates = None): """ Initialize DnsServiceManager object with full core configuration tree structure. :param dict core_config: Mentat core configuration structure. :param dict updates: Optional configuration updates (same structure as ``core_config``). """ self._dnsconfig = {} self._service = None self._configure_dns(core_config, updates) def _configure_dns(self, core_config, updates): """ Internal sub-initialization helper: Configure database structure parameters and optionally merge them with additional updates. :param dict core_config: Mentat core configuration structure. :param dict updates: Optional configuration updates (same structure as ``core_config``). """ self._dnsconfig = copy.deepcopy(core_config[CKEY_CORE_SERVICES][CKEY_CORE_SERVICES_DNS]) if updates and CKEY_CORE_SERVICES in updates and CKEY_CORE_SERVICES_DNS in updates[CKEY_CORE_SERVICES]: self._dnsconfig.update( updates[CKEY_CORE_SERVICES][CKEY_CORE_SERVICES_DNS] )
[docs] def service(self): """ Return handle to DNS service according to internal configurations. :return: Reference to DNS service object. :rtype: mentat.services.dnsr.DnsService """ if not self._service: self._service = DnsService(**self._dnsconfig) self._service.setup() return self._service
#-------------------------------------------------------------------------------
[docs]def init(core_config, updates = None): """ (Re-)Initialize :py:class:`DnsServiceManager` instance at module level and store the refence within module. """ global _MANAGER # pylint: disable=locally-disabled,global-statement _MANAGER = DnsServiceManager(core_config, updates)
[docs]def manager(): """ Obtain reference to :py:class:`DnsServiceManager` instance stored at module level. """ return _MANAGER
[docs]def service(): """ Obtain reference to :py:class:`DnsService` instance from module level manager. """ return manager().service()