# -*- 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/>.
#

__all__ = [ "Zone", "zone_reader", "zone_writer" ]

import xml.sax as sax
import os
import io
import shutil

from firewall import config
from firewall.functions import checkIP, checkIP6, checkIPnMask, checkIP6nMask, checkInterface, uniqify, max_zone_name_len, u2b_if_py2, check_mac, portStr
from firewall.core.base import DEFAULT_ZONE_TARGET, ZONE_TARGETS
from firewall.core.io.io_object import PY2, IO_Object, \
    IO_Object_ContentHandler, IO_Object_XMLGenerator, check_port, \
    check_tcpudp, check_protocol
from firewall.core import rich
from firewall.core.logger import log
from firewall import errors
from firewall.errors import FirewallError

class Zone(IO_Object):
    """ Zone class """

    IMPORT_EXPORT_STRUCTURE = (
        ( "version",  "" ),                            # s
        ( "short", "" ),                               # s
        ( "description", "" ),                         # s
        ( "UNUSED", False ),                           # b
        ( "target", "" ),                              # s
        ( "services", [ "", ], ),                      # as
        ( "ports", [ ( "", "" ), ], ),                 # a(ss)
        ( "icmp_blocks", [ "", ], ),                   # as
        ( "masquerade", False ),                       # b
        ( "forward_ports", [ ( "", "", "", "" ), ], ), # a(ssss)
        ( "interfaces", [ "" ] ),                      # as
        ( "sources", [ "" ] ),                         # as
        ( "rules_str", [ "" ] ),                       # as
        ( "protocols", [ "", ], ),                     # as
        ( "source_ports", [ ( "", "" ), ], ),          # a(ss)
        ( "icmp_block_inversion", False ),             # b
        )
    DBUS_SIGNATURE = '(sssbsasa(ss)asba(ssss)asasasasa(ss)b)'
    ADDITIONAL_ALNUM_CHARS = [ "_", "-", "/" ]
    PARSER_REQUIRED_ELEMENT_ATTRS = {
        "short": None,
        "description": None,
        "zone": None,
        "service": [ "name" ],
        "port": [ "port", "protocol" ],
        "icmp-block": [ "name" ],
        "icmp-type": [ "name" ],
        "forward-port": [ "port", "protocol" ],
        "interface": [ "name" ],
        "rule": None,
        "source": None,
        "destination": [ "address" ],
        "protocol": [ "value" ],
        "source-port": [ "port", "protocol" ],
        "log":  None,
        "audit": None,
        "accept": None,
        "reject": None,
        "drop": None,
        "mark": [ "set" ],
        "limit": [ "value" ],
        "icmp-block-inversion": None,
        }
    PARSER_OPTIONAL_ELEMENT_ATTRS = {
        "zone": [ "name", "immutable", "target", "version" ],
        "masquerade": [ "enabled" ],
        "forward-port": [ "to-port", "to-addr" ],
        "rule": [ "family" ],
        "source": [ "address", "mac", "invert", "family", "ipset" ],
        "destination": [ "invert" ],
        "log": [ "prefix", "level" ],
        "reject": [ "type" ],
        }

    @staticmethod
    def index_of(element):
        for i, (el, dummy) in enumerate(Zone.IMPORT_EXPORT_STRUCTURE):
            if el == element:
                return i
        raise FirewallError(errors.UNKNOWN_ERROR, "index_of()")

    def __init__(self):
        super(Zone, self).__init__()
        self.version = ""
        self.short = ""
        self.description = ""
        self.UNUSED = False
        self.target = DEFAULT_ZONE_TARGET
        self.services = [ ]
        self.ports = [ ]
        self.protocols = [ ]
        self.icmp_blocks = [ ]
        self.masquerade = False
        self.forward_ports = [ ]
        self.source_ports = [ ]
        self.interfaces = [ ]
        self.sources = [ ]
        self.fw_config = None # to be able to check services and a icmp_blocks
        self.rules = [ ]
        self.rules_str = [ ]
        self.icmp_block_inversion = False
        self.combined = False
        self.applied = False

    def cleanup(self):
        self.version = ""
        self.short = ""
        self.description = ""
        self.UNUSED = False
        self.target = DEFAULT_ZONE_TARGET
        del self.services[:]
        del self.ports[:]
        del self.protocols[:]
        del self.icmp_blocks[:]
        self.masquerade = False
        del self.forward_ports[:]
        del self.source_ports[:]
        del self.interfaces[:]
        del self.sources[:]
        self.fw_config = None # to be able to check services and a icmp_blocks
        del self.rules[:]
        del self.rules_str[:]
        self.icmp_block_inversion = False
        self.combined = False
        self.applied = False

    def encode_strings(self):
        """ HACK. I haven't been able to make sax parser return
            strings encoded (because of python 2) instead of in unicode.
            Get rid of it once we throw out python 2 support."""
        self.version = u2b_if_py2(self.version)
        self.short = u2b_if_py2(self.short)
        self.description = u2b_if_py2(self.description)
        self.target = u2b_if_py2(self.target)
        self.services = [u2b_if_py2(s) for s in self.services]
        self.ports = [(u2b_if_py2(po),u2b_if_py2(pr)) for (po,pr) in self.ports]
        self.protocols = [u2b_if_py2(pr) for pr in self.protocols]
        self.icmp_blocks = [u2b_if_py2(i) for i in self.icmp_blocks]
        self.forward_ports = [(u2b_if_py2(p1),u2b_if_py2(p2),u2b_if_py2(p3),u2b_if_py2(p4)) for (p1,p2,p3,p4) in self.forward_ports]
        self.source_ports = [(u2b_if_py2(po),u2b_if_py2(pr)) for (po,pr)
                             in self.source_ports]
        self.interfaces = [u2b_if_py2(i) for i in self.interfaces]
        self.sources = [u2b_if_py2(s) for s in self.sources]
        self.rules = [u2b_if_py2(s) for s in self.rules]
        self.rules_str = [u2b_if_py2(s) for s in self.rules_str]

    def __setattr__(self, name, value):
        if name == "rules_str":
            self.rules = [rich.Rich_Rule(rule_str=s) for s in value]
            # must convert back to string to get the canonical string.
            super(Zone, self).__setattr__(name, [str(s) for s in self.rules])
        else:
            super(Zone, self).__setattr__(name, value)

    def _check_config(self, config, item):
        if item == "services" and self.fw_config:
            existing_services = self.fw_config.get_services()
            for service in config:
                if service not in existing_services:
                    raise FirewallError(errors.INVALID_SERVICE,
                                        "'%s' not among existing services" % \
                                        service)
        elif item == "ports":
            for port in config:
                check_port(port[0])
                check_tcpudp(port[1])
        elif item == "protocols":
            for proto in config:
                check_protocol(proto)
        elif item == "icmp_blocks" and self.fw_config:
            existing_icmptypes = self.fw_config.get_icmptypes()
            for icmptype in config:
                if icmptype not in existing_icmptypes:
                    raise FirewallError(errors.INVALID_ICMPTYPE,
                                        "'%s' not among existing icmp types" % \
                                        icmptype)
        elif item == "forward_ports":
            for fwd_port in config:
                check_port(fwd_port[0])
                check_tcpudp(fwd_port[1])
                if not fwd_port[2] and not fwd_port[3]:
                    raise FirewallError(
                        errors.INVALID_FORWARD,
                        "'%s' is missing to-port AND to-addr " % fwd_port)
                if fwd_port[2]:
                    check_port(fwd_port[2])
                if fwd_port[3]:
                    if not checkIP(fwd_port[3]) and not checkIP6(fwd_port[3]):
                        raise FirewallError(
                            errors.INVALID_ADDR,
                            "to-addr '%s' is not a valid address" % fwd_port[3])
        elif item == "source_ports":
            for port in config:
                check_port(port[0])
                check_tcpudp(port[1])
        elif item == "target":
            if config not in ZONE_TARGETS:
                raise FirewallError(errors.INVALID_TARGET, config)
        elif item == "interfaces":
            for interface in config:
                if not checkInterface(interface):
                    raise FirewallError(errors.INVALID_INTERFACE, interface)
        elif item == "sources":
            for source in config:
                if not checkIPnMask(source) and not checkIP6nMask(source) and \
                   not check_mac(source) and not source.startswith("ipset:"):
                    raise FirewallError(errors.INVALID_ADDR, source)
        elif item == "rules_str":
            for rule in config:
                rich.Rich_Rule(rule_str=rule)

    def check_name(self, name):
        super(Zone, self).check_name(name)
        if name.startswith('/'):
            raise FirewallError(errors.INVALID_NAME,
                                "'%s' can't start with '/'" % name)
        elif name.endswith('/'):
            raise FirewallError(errors.INVALID_NAME,
                                "'%s' can't end with '/'" % name)
        elif name.count('/') > 1:
            raise FirewallError(errors.INVALID_NAME,
                                "more than one '/' in '%s'" % name)
        else:
            if "/" in name:
                checked_name = name[:name.find('/')]
            else:
                checked_name = name
            if len(checked_name) > max_zone_name_len():
                raise FirewallError(errors.INVALID_NAME,
                                    "Zone of '%s' has %d chars, max is %d %s" % (
                                    name, len(checked_name),
                                    max_zone_name_len(),
                                    self.combined))

    def combine(self, zone):
        self.combined = True
        self.filename = None
        self.version = ""
        self.short = ""
        self.description = ""

        for interface in zone.interfaces:
            if interface not in self.interfaces:
                self.interfaces.append(interface)
        for source in zone.sources:
            if source not in self.sources:
                self.sources.append(source)
        for service in zone.services:
            if service not in self.services:
                self.services.append(service)
        for port in zone.ports:
            if port not in self.ports:
                self.ports.append(port)
        for proto in zone.protocols:
            if proto not in self.protocols:
                self.protocols.append(proto)
        for icmp in zone.icmp_blocks:
            if icmp not in self.icmp_blocks:
                self.icmp_blocks.append(icmp)
        if zone.masquerade:
            self.masquerade = True
        for forward in zone.forward_ports:
            if forward not in self.forward_ports:
                self.forward_ports.append(forward)
        for port in zone.source_ports:
            if port not in self.source_ports:
                self.source_ports.append(port)
        for rule in zone.rules:
            self.rules.append(rule)
            self.rules_str.append(str(rule))
        if zone.icmp_block_inversion:
            self.icmp_block_inversion = True

# PARSER

class zone_ContentHandler(IO_Object_ContentHandler):
    def __init__(self, item):
        IO_Object_ContentHandler.__init__(self, item)
        self._rule = None
        self._rule_error = False
        self._limit_ok = None

    def startElement(self, name, attrs):
        IO_Object_ContentHandler.startElement(self, name, attrs)
        if self._rule_error:
            return

        self.item.parser_check_element_attrs(name, attrs)

        if name == "zone":
            if "name" in attrs:
                log.warning("Ignoring deprecated attribute name='%s'",
                            attrs["name"])
            if "version" in attrs:
                self.item.version = attrs["version"]
            if "immutable" in attrs:
                log.warning("Ignoring deprecated attribute immutable='%s'",
                            attrs["immutable"])
            if "target" in attrs:
                target = attrs["target"]
                if target not in ZONE_TARGETS:
                    raise FirewallError(errors.INVALID_TARGET, target)
                if target != "" and target != DEFAULT_ZONE_TARGET:
                    self.item.target = target

        elif name == "short":
            pass
        elif name == "description":
            pass
        elif name == "service":
            if self._rule:
                if self._rule.element:
                    log.warning("Invalid rule: More than one element in rule '%s', ignoring.",
                                str(self._rule))
                    self._rule_error = True
                    return
                self._rule.element = rich.Rich_Service(attrs["name"])
                return
            if attrs["name"] not in self.item.services:
                self.item.services.append(attrs["name"])
            else:
                log.warning("Service '%s' already set, ignoring.",
                            attrs["name"])

        elif name == "port":
            if self._rule:
                if self._rule.element:
                    log.warning("Invalid rule: More than one element in rule '%s', ignoring.",
                                str(self._rule))
                    self._rule_error = True
                    return
                self._rule.element = rich.Rich_Port(attrs["port"],
                                                    attrs["protocol"])
                return
            check_port(attrs["port"])
            check_tcpudp(attrs["protocol"])
            entry = (portStr(attrs["port"], "-"), attrs["protocol"])
            if entry not in self.item.ports:
                self.item.ports.append(entry)
            else:
                log.warning("Port '%s/%s' already set, ignoring.",
                            attrs["port"], attrs["protocol"])

        elif name == "protocol":
            if self._rule:
                if self._rule.element:
                    log.warning("Invalid rule: More than one element in rule '%s', ignoring.",
                                str(self._rule))
                    self._rule_error = True
                    return
                self._rule.element = rich.Rich_Protocol(attrs["value"])
            else:
                check_protocol(attrs["value"])
                if attrs["value"] not in self.item.protocols:
                    self.item.protocols.append(attrs["value"])
                else:
                    log.warning("Protocol '%s' already set, ignoring.",
                                attrs["value"])
        elif name == "icmp-block":
            if self._rule:
                if self._rule.element:
                    log.warning("Invalid rule: More than one element in rule '%s', ignoring.",
                                str(self._rule))
                    self._rule_error = True
                    return
                self._rule.element = rich.Rich_IcmpBlock(attrs["name"])
                return
            if attrs["name"] not in self.item.icmp_blocks:
                self.item.icmp_blocks.append(attrs["name"])
            else:
                log.warning("icmp-block '%s' already set, ignoring.",
                            attrs["name"])

        elif name == "icmp-type":
            if self._rule:
                if self._rule.element:
                    log.warning("Invalid rule: More than one element in rule '%s', ignoring.",
                                str(self._rule))
                    self._rule_error = True
                    return
                self._rule.element = rich.Rich_IcmpType(attrs["name"])
                return
            else:
                log.warning("Invalid rule: icmp-block '%s' outside of rule",
                            attrs["name"])

        elif name == "masquerade":
            if "enabled" in attrs and \
               attrs["enabled"].lower() in [ "no", "false" ] :
                log.warning("Ignoring deprecated attribute enabled='%s'",
                            attrs["enabled"])
                return

            if self._rule:
                if self._rule.element:
                    log.warning("Invalid rule: More than one element in rule '%s', ignoring.",
                                str(self._rule))
                    self._rule_error = True
                    return
                self._rule.element = rich.Rich_Masquerade()
            else:
                if self.item.masquerade:
                    log.warning("Masquerade already set, ignoring.")
                else:
                    self.item.masquerade = True

        elif name == "forward-port":
            to_port = ""
            if "to-port" in attrs:
                to_port = attrs["to-port"]
            to_addr = ""
            if "to-addr" in attrs:
                to_addr = attrs["to-addr"]

            if self._rule:
                if self._rule.element:
                    log.warning("Invalid rule: More than one element in rule '%s', ignoring.",
                                str(self._rule))
                    self._rule_error = True
                    return
                self._rule.element = rich.Rich_ForwardPort(attrs["port"],
                                                           attrs["protocol"],
                                                           to_port, to_addr)
                return

            check_port(attrs["port"])
            check_tcpudp(attrs["protocol"])
            if to_port:
                check_port(to_port)
            if to_addr:
                if not checkIP(to_addr) and not checkIP6(to_addr):
                    raise FirewallError(errors.INVALID_ADDR,
                                        "to-addr '%s' is not a valid address" \
                                        % to_addr)
            entry = (portStr(attrs["port"], "-"), attrs["protocol"],
                     portStr(to_port, "-"), str(to_addr))
            if entry not in self.item.forward_ports:
                self.item.forward_ports.append(entry)
            else:
                log.warning("Forward port %s/%s%s%s already set, ignoring.",
                            attrs["port"], attrs["protocol"],
                            " >%s" % to_port if to_port else "",
                            " @%s" % to_addr if to_addr else "")

        elif name == "source-port":
            if self._rule:
                if self._rule.element:
                    log.warning("Invalid rule: More than one element in rule '%s', ignoring.",
                                str(self._rule))
                    self._rule_error = True
                    return
                self._rule.element = rich.Rich_SourcePort(attrs["port"],
                                                          attrs["protocol"])
                return
            check_port(attrs["port"])
            check_tcpudp(attrs["protocol"])
            entry = (portStr(attrs["port"], "-"), attrs["protocol"])
            if entry not in self.item.source_ports:
                self.item.source_ports.append(entry)
            else:
                log.warning("Source port '%s/%s' already set, ignoring.",
                            attrs["port"], attrs["protocol"])

        elif name == "interface":
            if self._rule:
                log.warning('Invalid rule: interface use in rule.')
                self._rule_error = True
                return
            # zone bound to interface
            if "name" not in attrs:
                log.warning('Invalid interface: Name missing.')
                self._rule_error = True
                return
            if attrs["name"] not in self.item.interfaces:
                self.item.interfaces.append(attrs["name"])
            else:
                log.warning("Interface '%s' already set, ignoring.",
                            attrs["name"])

        elif name == "source":
            if self._rule:
                if self._rule.source:
                    log.warning("Invalid rule: More than one source in rule '%s', ignoring.",
                                str(self._rule))
                    self._rule_error = True
                    return
                invert = False
                if "invert" in attrs and \
                        attrs["invert"].lower() in [ "yes", "true" ]:
                    invert = True
                addr = mac = ipset = None
                if "address" in attrs:
                    addr = attrs["address"]
                if "mac" in attrs:
                    mac = attrs["mac"]
                if "ipset" in attrs:
                    ipset = attrs["ipset"]
                self._rule.source = rich.Rich_Source(addr, mac, ipset,
                                                     invert=invert)
                return
            # zone bound to source
            if "address" not in attrs and "ipset" not in attrs:
                log.warning('Invalid source: No address no ipset.')
                return
            if "address" in attrs and "ipset" in attrs:
                log.warning('Invalid source: Address and ipset.')
                return
            if "family" in attrs:
                log.warning("Ignoring deprecated attribute family='%s'",
                            attrs["family"])
            if "invert" in attrs:
                log.warning('Invalid source: Invertion not allowed here.')
                return
            if "address" in attrs:
                if not checkIPnMask(attrs["address"]) and \
                   not checkIP6nMask(attrs["address"]) and \
                   not check_mac(attrs["address"]):
                    raise FirewallError(errors.INVALID_ADDR, attrs["address"])
            if "ipset" in attrs:
                entry = "ipset:%s" % attrs["ipset"]
                if entry not in self.item.sources:
                    self.item.sources.append(entry)
                else:
                    log.warning("Source '%s' already set, ignoring.",
                                attrs["address"])
            if "address" in attrs:
                entry = attrs["address"]
                if entry not in self.item.sources:
                    self.item.sources.append(entry)
                else:
                    log.warning("Source '%s' already set, ignoring.",
                                attrs["address"])

        elif name == "destination":
            if not self._rule:
                log.warning('Invalid rule: Destination outside of rule')
                self._rule_error = True
                return
            if self._rule.destination:
                log.warning("Invalid rule: More than one destination in rule '%s', ignoring.",
                            str(self._rule))
                return
            invert = False
            if "invert" in attrs and \
                    attrs["invert"].lower() in [ "yes", "true" ]:
                invert = True
            self._rule.destination = rich.Rich_Destination(attrs["address"],
                                                           invert)

        elif name in [ "accept", "reject", "drop", "mark" ]:
            if not self._rule:
                log.warning('Invalid rule: Action outside of rule')
                self._rule_error = True
                return
            if self._rule.action:
                log.warning('Invalid rule: More than one action')
                self._rule_error = True
                return
            if name == "accept":
                self._rule.action = rich.Rich_Accept()
            elif name == "reject":
                _type = None
                if "type" in attrs:
                    _type = attrs["type"]
                self._rule.action = rich.Rich_Reject(_type)
            elif name == "drop":
                self._rule.action = rich.Rich_Drop()
            elif name == "mark":
                _set = attrs["set"]
                self._rule.action = rich.Rich_Mark(_set)
            self._limit_ok = self._rule.action

        elif name == "log":
            if not self._rule:
                log.warning('Invalid rule: Log outside of rule')
                return
            if self._rule.log:
                log.warning('Invalid rule: More than one log')
                return
            level = None
            if "level" in attrs:
                level = attrs["level"]
                if level not in [ "emerg", "alert", "crit", "error",
                                  "warning", "notice", "info", "debug" ]:
                    log.warning('Invalid rule: Invalid log level')
                    self._rule_error = True
                    return
            prefix = attrs["prefix"] if "prefix" in attrs else None
            self._rule.log = rich.Rich_Log(prefix, level)
            self._limit_ok = self._rule.log

        elif name == "audit":
            if not self._rule:
                log.warning('Invalid rule: Audit outside of rule')
                return
            if self._rule.audit:
                log.warning("Invalid rule: More than one audit in rule '%s', ignoring.",
                            str(self._rule))
                self._rule_error = True
                return
            self._rule.audit = rich.Rich_Audit()
            self._limit_ok = self._rule.audit

        elif name == "rule":
            family = None
            if "family" in attrs:
                family = attrs["family"]
                if family not in [ "ipv4", "ipv6" ]:
                    log.warning('Invalid rule: Rule family "%s" invalid',
                                attrs["family"])
                    self._rule_error = True
                    return
            self._rule = rich.Rich_Rule(family)

        elif name == "limit":
            if not self._limit_ok:
                log.warning('Invalid rule: Limit outside of action, log and audit')
                self._rule_error = True
                return
            if self._limit_ok.limit:
                log.warning("Invalid rule: More than one limit in rule '%s', ignoring.",
                            str(self._rule))
                self._rule_error = True
                return
            value = attrs["value"]
            self._limit_ok.limit = rich.Rich_Limit(value)

        elif name == "icmp-block-inversion":
            if self.item.icmp_block_inversion:
                log.warning("Icmp-Block-Inversion already set, ignoring.")
            else:
                self.item.icmp_block_inversion = True

        else:
            log.warning("Unknown XML element '%s'", name)
            return

    def endElement(self, name):
        IO_Object_ContentHandler.endElement(self, name)

        if name == "rule":
            if not self._rule_error:
                try:
                    self._rule.check()
                except Exception as e:
                    log.warning("%s: %s", e, str(self._rule))
                else:
                    if str(self._rule) not in self.item.rules_str:
                        self.item.rules.append(self._rule)
                        self.item.rules_str.append(str(self._rule))
                    else:
                        log.warning("Rule '%s' already set, ignoring.",
                                    str(self._rule))
            self._rule = None
            self._rule_error = False
        elif name in [ "accept", "reject", "drop", "mark", "log", "audit" ]:
            self._limit_ok = None

def zone_reader(filename, path, no_check_name=False):
    zone = Zone()
    if not filename.endswith(".xml"):
        raise FirewallError(errors.INVALID_NAME,
                            "'%s' is missing .xml suffix" % filename)
    zone.name = filename[:-4]
    if not no_check_name:
        zone.check_name(zone.name)
    zone.filename = filename
    zone.path = path
    zone.builtin = False if path.startswith(config.ETC_FIREWALLD) else True
    zone.default = zone.builtin
    handler = zone_ContentHandler(zone)
    parser = sax.make_parser()
    parser.setContentHandler(handler)
    name = "%s/%s" % (path, filename)
    with open(name, "rb") as f:
        source = sax.InputSource(None)
        source.setByteStream(f)
        try:
            parser.parse(source)
        except sax.SAXParseException as msg:
            raise FirewallError(errors.INVALID_ZONE,
                                "not a valid zone file: %s" % \
                                msg.getException())
    del handler
    del parser
    if PY2:
        zone.encode_strings()
    return zone

def zone_writer(zone, path=None):
    _path = path if path else zone.path

    if zone.filename:
        name = "%s/%s" % (_path, zone.filename)
    else:
        name = "%s/%s.xml" % (_path, zone.name)

    if os.path.exists(name):
        try:
            shutil.copy2(name, "%s.old" % name)
        except Exception as msg:
            log.error("Backup of file '%s' failed: %s", name, msg)

    dirpath = os.path.dirname(name)
    if dirpath.startswith(config.ETC_FIREWALLD) and not os.path.exists(dirpath):
        if not os.path.exists(config.ETC_FIREWALLD):
            os.mkdir(config.ETC_FIREWALLD, 0o750)
        os.mkdir(dirpath, 0o750)

    f = io.open(name, mode='wt', encoding='UTF-8')
    handler = IO_Object_XMLGenerator(f)
    handler.startDocument()

    # start zone element
    attrs = {}
    if zone.version and zone.version != "":
        attrs["version"] = zone.version
    if zone.target != DEFAULT_ZONE_TARGET:
        attrs["target"] = zone.target
    handler.startElement("zone", attrs)
    handler.ignorableWhitespace("\n")

    # short
    if zone.short and zone.short != "":
        handler.ignorableWhitespace("  ")
        handler.startElement("short", { })
        handler.characters(zone.short)
        handler.endElement("short")
        handler.ignorableWhitespace("\n")

    # description
    if zone.description and zone.description != "":
        handler.ignorableWhitespace("  ")
        handler.startElement("description", { })
        handler.characters(zone.description)
        handler.endElement("description")
        handler.ignorableWhitespace("\n")

    # interfaces
    for interface in uniqify(zone.interfaces):
        handler.ignorableWhitespace("  ")
        handler.simpleElement("interface", { "name": interface })
        handler.ignorableWhitespace("\n")

    # source
    for source in uniqify(zone.sources):
        handler.ignorableWhitespace("  ")
        if "ipset:" in source:
            handler.simpleElement("source", { "ipset": source[6:] })
        else:
            handler.simpleElement("source", { "address": source })
        handler.ignorableWhitespace("\n")

    # services
    for service in uniqify(zone.services):
        handler.ignorableWhitespace("  ")
        handler.simpleElement("service", { "name": service })
        handler.ignorableWhitespace("\n")

    # ports
    for port in uniqify(zone.ports):
        handler.ignorableWhitespace("  ")
        handler.simpleElement("port", { "port": port[0], "protocol": port[1] })
        handler.ignorableWhitespace("\n")

    # protocols
    for protocol in uniqify(zone.protocols):
        handler.ignorableWhitespace("  ")
        handler.simpleElement("protocol", { "value": protocol })
        handler.ignorableWhitespace("\n")

    # icmp-block-inversion
    if zone.icmp_block_inversion:
        handler.ignorableWhitespace("  ")
        handler.simpleElement("icmp-block-inversion", { })
        handler.ignorableWhitespace("\n")

    # icmp-blocks
    for icmp in uniqify(zone.icmp_blocks):
        handler.ignorableWhitespace("  ")
        handler.simpleElement("icmp-block", { "name": icmp })
        handler.ignorableWhitespace("\n")

    # masquerade
    if zone.masquerade:
        handler.ignorableWhitespace("  ")
        handler.simpleElement("masquerade", { })
        handler.ignorableWhitespace("\n")

    # forward-ports
    for forward in uniqify(zone.forward_ports):
        handler.ignorableWhitespace("  ")
        attrs = { "port": forward[0], "protocol": forward[1] }
        if forward[2] and forward[2] != "" :
            attrs["to-port"] = forward[2]
        if forward[3] and forward[3] != "" :
            attrs["to-addr"] = forward[3]
        handler.simpleElement("forward-port", attrs)
        handler.ignorableWhitespace("\n")

    # source-ports
    for port in uniqify(zone.source_ports):
        handler.ignorableWhitespace("  ")
        handler.simpleElement("source-port", { "port": port[0],
                                               "protocol": port[1] })
        handler.ignorableWhitespace("\n")

    # rules
    for rule in zone.rules:
        attrs = { }
        if rule.family:
            attrs["family"] = rule.family
        handler.ignorableWhitespace("  ")
        handler.startElement("rule", attrs)
        handler.ignorableWhitespace("\n")

        # source
        if rule.source:
            attrs = { }
            if rule.source.addr:
                attrs["address"] = rule.source.addr
            if rule.source.mac:
                attrs["mac"] = rule.source.mac
            if rule.source.ipset:
                attrs["ipset"] = rule.source.ipset
            if rule.source.invert:
                attrs["invert"] = "True"
            handler.ignorableWhitespace("    ")
            handler.simpleElement("source", attrs)
            handler.ignorableWhitespace("\n")

        # destination
        if rule.destination:
            attrs = { "address": rule.destination.addr }
            if rule.destination.invert:
                attrs["invert"] = "True"
            handler.ignorableWhitespace("    ")
            handler.simpleElement("destination", attrs)
            handler.ignorableWhitespace("\n")

        # element
        if rule.element:
            element = ""
            attrs = { }

            if type(rule.element) == rich.Rich_Service:
                element = "service"
                attrs["name"] = rule.element.name
            elif type(rule.element) == rich.Rich_Port:
                element = "port"
                attrs["port"] = rule.element.port
                attrs["protocol"] = rule.element.protocol
            elif type(rule.element) == rich.Rich_Protocol:
                element = "protocol"
                attrs["value"] = rule.element.value
            elif type(rule.element) == rich.Rich_Masquerade:
                element = "masquerade"
            elif type(rule.element) == rich.Rich_IcmpBlock:
                element = "icmp-block"
                attrs["name"] = rule.element.name
            elif type(rule.element) == rich.Rich_IcmpType:
                element = "icmp-type"
                attrs["name"] = rule.element.name
            elif type(rule.element) == rich.Rich_ForwardPort:
                element = "forward-port"
                attrs["port"] = rule.element.port
                attrs["protocol"] = rule.element.protocol
                if rule.element.to_port != "":
                    attrs["to-port"] = rule.element.to_port
                if rule.element.to_address != "":
                    attrs["to-addr"] = rule.element.to_address
            elif type(rule.element) == rich.Rich_SourcePort:
                element = "source-port"
                attrs["port"] = rule.element.port
                attrs["protocol"] = rule.element.protocol
            else:
                raise FirewallError(
                    errors.INVALID_OBJECT,
                    "Unknown element '%s' in zone_writer" % type(rule.element))

            handler.ignorableWhitespace("    ")
            handler.simpleElement(element, attrs)
            handler.ignorableWhitespace("\n")

        # rule.element

        # log
        if rule.log:
            attrs = { }
            if rule.log.prefix:
                attrs["prefix"] = rule.log.prefix
            if rule.log.level:
                attrs["level"] = rule.log.level
            if rule.log.limit:
                handler.ignorableWhitespace("    ")
                handler.startElement("log", attrs)
                handler.ignorableWhitespace("\n      ")
                handler.simpleElement("limit",
                                      { "value": rule.log.limit.value })
                handler.ignorableWhitespace("\n    ")
                handler.endElement("log")
            else:
                handler.ignorableWhitespace("    ")
                handler.simpleElement("log", attrs)
            handler.ignorableWhitespace("\n")

        # audit
        if rule.audit:
            attrs = {}
            if rule.audit.limit:
                handler.ignorableWhitespace("    ")
                handler.startElement("audit", { })
                handler.ignorableWhitespace("\n      ")
                handler.simpleElement("limit",
                                      { "value": rule.audit.limit.value })
                handler.ignorableWhitespace("\n    ")
                handler.endElement("audit")
            else:
                handler.ignorableWhitespace("    ")
                handler.simpleElement("audit", attrs)
            handler.ignorableWhitespace("\n")

        # action
        if rule.action:
            action = ""
            attrs = { }
            if type(rule.action) == rich.Rich_Accept:
                action = "accept"
            elif type(rule.action) == rich.Rich_Reject:
                action = "reject"
                if rule.action.type:
                    attrs["type"] = rule.action.type
            elif type(rule.action) == rich.Rich_Drop:
                action = "drop"
            elif type(rule.action) == rich.Rich_Mark:
                action = "mark"
                attrs["set"] = rule.action.set
            else:
                log.warning("Unknown action '%s'", type(rule.action))
            if rule.action.limit:
                handler.ignorableWhitespace("    ")
                handler.startElement(action, attrs)
                handler.ignorableWhitespace("\n      ")
                handler.simpleElement("limit",
                                      { "value": rule.action.limit.value })
                handler.ignorableWhitespace("\n    ")
                handler.endElement(action)
            else:
                handler.ignorableWhitespace("    ")
                handler.simpleElement(action, attrs)
            handler.ignorableWhitespace("\n")

        handler.ignorableWhitespace("  ")
        handler.endElement("rule")
        handler.ignorableWhitespace("\n")

    # end zone element
    handler.endElement("zone")
    handler.ignorableWhitespace("\n")
    handler.endDocument()
    f.close()
    del handler
