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# -*- coding: utf-8 -*-
#
# Copyright (C) 2011-2016 Red Hat, Inc.
#
# Authors:
# Thomas Woerner <twoerner@redhat.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

"""Generic io_object handler, io specific check methods."""

__all__ = [ "PY2",
            "IO_Object", "IO_Object_ContentHandler", "IO_Object_XMLGenerator",
            "check_port", "check_tcpudp", "check_protocol", "check_address" ]

import xml.sax as sax
import xml.sax.saxutils as saxutils
import copy
import sys
from collections import OrderedDict

from firewall import functions
from firewall.functions import b2u
from firewall import errors
from firewall.errors import FirewallError

PY2 = sys.version < '3'

class IO_Object(object):
    """ Abstract IO_Object as base for icmptype, service and zone """

    IMPORT_EXPORT_STRUCTURE = ( )
    DBUS_SIGNATURE = '()'
    ADDITIONAL_ALNUM_CHARS = [ ] # additional to alnum
    PARSER_REQUIRED_ELEMENT_ATTRS = { }
    PARSER_OPTIONAL_ELEMENT_ATTRS = { }

    def __init__(self):
        self.filename = ""
        self.path = ""
        self.name = ""
        self.default = False
        self.builtin = False

    def export_config(self):
        ret = [ ]
        for x in self.IMPORT_EXPORT_STRUCTURE:
            ret.append(copy.deepcopy(getattr(self, x[0])))
        return tuple(ret)

    def export_config_dict(self):
        conf = {}
        type_formats = dict([(x[0], x[1]) for x in self.IMPORT_EXPORT_STRUCTURE])
        for key in type_formats:
            if getattr(self, key) or isinstance(getattr(self, key), bool):
                conf[key] = copy.deepcopy(getattr(self, key))
        return conf

    def import_config(self, conf):
        self.check_config(conf)
        for i,(element,dummy) in enumerate(self.IMPORT_EXPORT_STRUCTURE):
            if isinstance(conf[i], list):
                # remove duplicates without changing the order
                _conf = [ ]
                _set = set()
                for x in conf[i]:
                    if x not in _set:
                        _conf.append(x)
                        _set.add(x)
                del _set
                setattr(self, element, copy.deepcopy(_conf))
            else:
                setattr(self, element, copy.deepcopy(conf[i]))

    def import_config_dict(self, conf):
        self.check_config_dict(conf)

        for key in conf:
            if not hasattr(self, key):
                raise FirewallError(errors.UNKNOWN_ERROR, "Internal error. '{}' is not a valid attribute".format(key))
            if isinstance(conf[key], list):
                # maintain list order while removing duplicates
                setattr(self, key, list(OrderedDict.fromkeys(copy.deepcopy(conf[key]))))
            else:
                setattr(self, key, copy.deepcopy(conf[key]))

    def check_name(self, name):
        if not isinstance(name, str):
            raise FirewallError(errors.INVALID_TYPE,
                                "'%s' not of type %s, but %s" % (name, type(""),
                                                                 type(name)))
        if len(name) < 1:
            raise FirewallError(errors.INVALID_NAME, "name can't be empty")
        for char in name:
            if not char.isalnum() and char not in self.ADDITIONAL_ALNUM_CHARS:
                raise FirewallError(
                    errors.INVALID_NAME,
                    "'%s' is not allowed in '%s'" % ((char, name)))

    def check_config(self, conf):
        if len(conf) != len(self.IMPORT_EXPORT_STRUCTURE):
            raise FirewallError(
                errors.INVALID_TYPE,
                "structure size mismatch %d != %d" % \
                (len(conf), len(self.IMPORT_EXPORT_STRUCTURE)))
        conf_dict = {}
        for i,(x,y) in enumerate(self.IMPORT_EXPORT_STRUCTURE):
            conf_dict[x] = conf[i]
        self.check_config_dict(conf_dict)

    def check_config_dict(self, conf):
        type_formats = dict([(x[0], x[1]) for x in self.IMPORT_EXPORT_STRUCTURE])
        for key in conf:
            if key not in [x for (x,y) in self.IMPORT_EXPORT_STRUCTURE]:
                raise FirewallError(errors.INVALID_OPTION, "option '{}' is not valid".format(key))
            self._check_config_structure(conf[key], type_formats[key])
            self._check_config(conf[key], key, conf)

    def _check_config(self, dummy1, dummy2, dummy3):
        # to be overloaded by sub classes
        return

    def _check_config_structure(self, conf, structure):
        if not isinstance(conf, type(structure)):
            raise FirewallError(errors.INVALID_TYPE,
                                "'%s' not of type %s, but %s" % \
                                (conf, type(structure), type(conf)))
        if isinstance(structure, list):
            # same type elements, else struct
            if len(structure) != 1:
                raise FirewallError(errors.INVALID_TYPE,
                                    "len('%s') != 1" % structure)
            for x in conf:
                self._check_config_structure(x, structure[0])
        elif isinstance(structure, tuple):
            if len(structure) != len(conf):
                raise FirewallError(errors.INVALID_TYPE,
                                    "len('%s') != %d" % (conf,
                                                         len(structure)))
            for i,value in enumerate(structure):
                self._check_config_structure(conf[i], value)
        elif isinstance(structure, dict):
            # only one key value pair in structure
            (skey, svalue) = list(structure.items())[0]
            for (key, value) in conf.items():
                if not isinstance(key, type(skey)):
                    raise FirewallError(errors.INVALID_TYPE,
                                        "'%s' not of type %s, but %s" % (\
                            key, type(skey), type(key)))
                if not isinstance(value, type(svalue)):
                    raise FirewallError(errors.INVALID_TYPE,
                                        "'%s' not of type %s, but %s" % (\
                            value, type(svalue), type(value)))

    # check required elements and attributes and also optional attributes
    def parser_check_element_attrs(self, name, attrs):
        _attrs = attrs.getNames()

        found = False
        if name in self.PARSER_REQUIRED_ELEMENT_ATTRS:
            found = True
            if self.PARSER_REQUIRED_ELEMENT_ATTRS[name] is not None:
                for x in self.PARSER_REQUIRED_ELEMENT_ATTRS[name]:
                    if x in _attrs:
                        _attrs.remove(x)
                    else:
                        raise FirewallError(
                            errors.PARSE_ERROR,
                            "Missing attribute %s for %s" % (x, name))
        if name in self.PARSER_OPTIONAL_ELEMENT_ATTRS:
            found = True
            for x in self.PARSER_OPTIONAL_ELEMENT_ATTRS[name]:
                if x in _attrs:
                    _attrs.remove(x)
        if not found:
            raise FirewallError(errors.PARSE_ERROR,
                                "Unexpected element %s" % name)
        # raise attributes[0]
        for x in _attrs:
            raise FirewallError(errors.PARSE_ERROR,
                                "%s: Unexpected attribute %s" % (name, x))

# PARSER

class UnexpectedElementError(Exception):
    def __init__(self, name):
        super(UnexpectedElementError, self).__init__()
        self.name = name
    def __str__(self):
        return "Unexpected element '%s'" % (self.name)

class MissingAttributeError(Exception):
    def __init__(self, name, attribute):
        super(MissingAttributeError, self).__init__()
        self.name = name
        self.attribute = attribute
    def __str__(self):
        return "Element '%s': missing '%s' attribute" % \
            (self.name, self.attribute)

class UnexpectedAttributeError(Exception):
    def __init__(self, name, attribute):
        super(UnexpectedAttributeError, self).__init__()
        self.name = name
        self.attribute = attribute
    def __str__(self):
        return "Element '%s': unexpected attribute '%s'" % \
            (self.name, self.attribute)

class IO_Object_ContentHandler(sax.handler.ContentHandler):
    def __init__(self, item):
        self.item = item
        self._element = ""

    def startDocument(self):
        self._element = ""

    def startElement(self, name, attrs):
        self._element = ""

    def endElement(self, name):
        if name == "short":
            self.item.short = self._element
        elif name == "description":
            self.item.description = self._element

    def characters(self, content):
        self._element += content.replace('\n', ' ')

class IO_Object_XMLGenerator(saxutils.XMLGenerator):
    def __init__(self, out):
        # fix memory leak in saxutils.XMLGenerator.__init__:
        #   out = _gettextwriter(out, encoding)
        # creates unbound object results in garbage in gc
        #
        # saxutils.XMLGenerator.__init__(self, out, "utf-8")
        #   replaced by modified saxutils.XMLGenerator.__init__ code:
        sax.handler.ContentHandler.__init__(self)
        self._write = out.write
        self._flush = out.flush
        self._ns_contexts = [{}] # contains uri -> prefix dicts
        self._current_context = self._ns_contexts[-1]
        self._undeclared_ns_maps = []
        self._encoding = "utf-8"
        self._pending_start_element = False
        self._short_empty_elements = False

    def startElement(self, name, attrs):
        """ saxutils.XMLGenerator.startElement() expects name and attrs to be
            unicode and bad things happen if any of them is (utf-8) encoded.
            We override the method here to sanitize this case.
            Can be removed once we drop Python2 support.
        """
        if PY2:
            attrs = { b2u(name):b2u(value) for name, value in attrs.items() }
        saxutils.XMLGenerator.startElement(self, name, attrs)

    def simpleElement(self, name, attrs):
        """ slightly modified startElement()
        """
        if PY2:
            self._write(u'<' + b2u(name))
            for (name, value) in attrs.items():
                self._write(u' %s=%s' % (b2u(name),
                                         saxutils.quoteattr(b2u(value))))
            self._write(u'/>')
        else:
            self._write('<' + name)
            for (name, value) in attrs.items():
                self._write(' %s=%s' % (name, saxutils.quoteattr(value)))
            self._write('/>')

    def endElement(self, name):
        """ saxutils.XMLGenerator.endElement() expects name to be
            unicode and bad things happen if it's (utf-8) encoded.
            We override the method here to sanitize this case.
            Can be removed once we drop Python2 support.
        """
        saxutils.XMLGenerator.endElement(self, b2u(name))

    def characters(self, content):
        """ saxutils.XMLGenerator.characters() expects content to be
            unicode and bad things happen if it's (utf-8) encoded.
            We override the method here to sanitize this case.
            Can be removed once we drop Python2 support.
        """
        saxutils.XMLGenerator.characters(self, b2u(content))

    def ignorableWhitespace(self, content):
        """ saxutils.XMLGenerator.ignorableWhitespace() expects content to be
            unicode and bad things happen if it's (utf-8) encoded.
            We override the method here to sanitize this case.
            Can be removed once we drop Python2 support.
        """
        saxutils.XMLGenerator.ignorableWhitespace(self, b2u(content))

def check_port(port):
    port_range = functions.getPortRange(port)
    if port_range == -2:
        raise FirewallError(errors.INVALID_PORT,
                            "port number in '%s' is too big" % port)
    elif port_range == -1:
        raise FirewallError(errors.INVALID_PORT,
                            "'%s' is invalid port range" % port)
    elif port_range is None:
        raise FirewallError(errors.INVALID_PORT,
                            "port range '%s' is ambiguous" % port)
    elif len(port_range) == 2 and port_range[0] >= port_range[1]:
        raise FirewallError(errors.INVALID_PORT,
                            "'%s' is invalid port range" % port)

def check_tcpudp(protocol):
    if protocol not in [ "tcp", "udp", "sctp", "dccp" ]:
        raise FirewallError(errors.INVALID_PROTOCOL,
                            "'%s' not from {'tcp'|'udp'|'sctp'|'dccp'}" % \
                            protocol)

def check_protocol(protocol):
    if not functions.checkProtocol(protocol):
        raise FirewallError(errors.INVALID_PROTOCOL, protocol)

def check_address(ipv, addr):
    if not functions.check_address(ipv, addr):
        raise FirewallError(errors.INVALID_ADDR,
                            "'%s' is not valid %s address" % (addr, ipv))