# Authors:
#   Jason Gerard DeRose <jderose@redhat.com>
#   Rob Crittenden <rcritten@redhat.com>
#   Pavel Zuna <pzuna@redhat.com>
#
# Copyright (C) 2008  Red Hat
# see file 'COPYING' for use and warranty information
#
# 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; version 2 only
#
# 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, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
"""
Services (Identity)

A service represents a running service on a host. This service record
may store a kerberos principal or an SSL certificate (or both).

A service may be managed directly by a machine, if it has been given
the proper permission (even a machine other than the one the service is
associated with). An example of this is requesting an SSL certificate
using the host service principal credentials of the host.

Adding a service makes it possible to request an SSL certificate or
keytab for that service but this is done as a separate step later. The
creation of a service in itself doesn't generate these.

The certificate stored in a service is just the public portion. The
private key is not stored.

EXAMPLES:

 Add a service:
   ipa service-add HTTP/web.example.com

 Allow a host to manage the service certificate:
  ipa service-add-host --hosts=web.example.com HTTP/web.example.com
  ipa rolegroup-add-member --hosts=web.example.com certadmin

 Remove a service:
   ipa service-del HTTP/web.example.com

 Find all services for a host:
   ipa service-find web.example.com

 Find all HTTP services:
   ipa service-find HTTP

 Disable a service kerberos key:
   ipa service-disable HTTP/web.example.com

"""
import base64

from ipalib import api, errors, util
from ipalib import Str, Flag, Bytes
from ipalib.plugins.baseldap import *
from ipalib import x509
from ipalib import _, ngettext


def split_principal(principal):
    service = hostname = realm = None

    # Break down the principal into its component parts, which may or
    # may not include the realm.
    sp = principal.split('/')
    if len(sp) != 2:
        raise errors.MalformedServicePrincipal(reason='missing service')

    service = sp[0]
    sr = sp[1].split('@')
    if len(sr) > 2:
        raise errors.MalformedServicePrincipal(
            reason='unable to determine realm'
        )

    hostname = sr[0].lower()
    if len(sr) == 2:
        realm = sr[1].upper()
        # At some point we'll support multiple realms
        if realm != api.env.realm:
            raise errors.RealmMismatch()
    else:
        realm = api.env.realm

    # Note that realm may be None.
    return (service, hostname, realm)

def validate_principal(ugettext, principal):
    (service, hostname, principal) = split_principal(principal)
    return None

def normalize_principal(principal):
    # The principal is already validated when it gets here
    (service, hostname, realm) = split_principal(principal)
    # Put the principal back together again
    principal = '%s/%s@%s' % (service, hostname, realm)
    return unicode(principal)

def validate_certificate(ugettext, cert):
    """
    For now just verify that it is properly base64-encoded.
    """
    try:
        base64.b64decode(cert)
    except Exception, e:
        raise errors.Base64DecodeError(reason=str(e))


class service(LDAPObject):
    """
    Service object.
    """
    container_dn = api.env.container_service
    object_name = 'service'
    object_name_plural = 'services'
    object_class = [
        'krbprincipal', 'krbprincipalaux', 'krbticketpolicyaux', 'ipaobject',
        'ipaservice', 'pkiuser'
    ]
    search_attributes = ['krbprincipalname', 'managedby']
    default_attributes = ['krbprincipalname', 'usercertificate', 'managedby', 'krblastpwdchange']
    uuid_attribute = 'ipauniqueid'
    attribute_members = {
        'managedby': ['host'],
    }

    label = _('Services')

    takes_params = (
        Str('krbprincipalname', validate_principal,
            cli_name='principal',
            label=_('Principal'),
            doc=_('Service principal'),
            primary_key=True,
            normalizer=lambda value: normalize_principal(value),
        ),
    )

api.register(service)


class service_add(LDAPCreate):
    """
    Add new service.
    """
    msg_summary = _('Added service "%(value)s"')
    member_attributes = ['managedby']
    takes_options = (
        Flag('force',
            doc=_('force principal name even if not in DNS'),
        ),
        Bytes('usercertificate?', validate_certificate,
            cli_name='certificate',
            label=_('Certificate'),
            doc=_('Base-64 encoded server certificate'),
        ),
    )
    def pre_callback(self, ldap, dn, entry_attrs, attrs_list, *keys, **options):
        (service, hostname, realm) = split_principal(keys[-1])
        if service.lower() == 'host' and not options['force']:
            raise errors.HostService()

        try:
            api.Command['host_show'](hostname)
        except errors.NotFound:
            raise errors.NotFound(reason="The host '%s' does not exist to add a service to." % hostname)

        cert = entry_attrs.get('usercertificate')
        if cert:
            cert = cert[0]
            # FIXME: should be in a normalizer: need to fix normalizers
            #        to work on non-unicode data
            entry_attrs['usercertificate'] = base64.b64decode(cert)
            # FIXME: shouldn't we request signing at this point?

        if not options.get('force', False):
             # We know the host exists if we've gotten this far but we
             # really want to discourage creating services for hosts that
             # don't exist in DNS.
             util.validate_host_dns(self.log, hostname)

        return dn

api.register(service_add)


class service_del(LDAPDelete):
    """
    Delete an existing service.
    """
    msg_summary = _('Deleted service "%(value)s"')
    member_attributes = ['managedby']
    def pre_callback(self, ldap, dn, *keys, **options):
        if self.api.env.enable_ra:
            (dn, entry_attrs) = ldap.get_entry(dn, ['usercertificate'])
            cert = entry_attrs.get('usercertificate')
            if cert:
                cert = cert[0]
                serial = unicode(x509.get_serial_number(cert, x509.DER))
                try:
                    result = api.Command['cert_show'](unicode(serial))['result']
                    if 'revocation_reason' not in result:
                        try:
                            api.Command['cert_revoke'](unicode(serial), revocation_reason=4)
                        except errors.NotImplementedError:
                            # some CA's might not implement revoke
                            pass
                except errors.NotImplementedError:
                    # some CA's might not implement revoke
                    pass
        return dn

api.register(service_del)


class service_mod(LDAPUpdate):
    """
    Modify service.
    """
    takes_options = LDAPUpdate.takes_options + (
        Bytes('usercertificate?', validate_certificate,
            cli_name='certificate',
            label=_('Certificate'),
            doc=_('Base-64 encoded server certificate'),
        ),
    )

    member_attributes = ['managedby']

    def pre_callback(self, ldap, dn, entry_attrs, *keys, **options):
        if 'usercertificate' in options:
            cert = options.get('usercertificate')
            if cert:
                (dn, entry_attrs_old) = ldap.get_entry(dn, ['usercertificate'])
                if 'usercertificate' in entry_attrs_old:
                    # FIXME: what to do here? do we revoke the old cert?
                    fmt = 'entry already has a certificate, serial number: %s' % (
                        x509.get_serial_number(entry_attrs_old['usercertificate'][0], x509.DER)
                    )
                    raise errors.GenericError(format=fmt)
                # FIXME: should be in normalizer; see service_add
                entry_attrs['usercertificate'] = base64.b64decode(cert)
            else:
                entry_attrs['usercertificate'] = None
        return dn

api.register(service_mod)


class service_find(LDAPSearch):
    """
    Search for services.
    """
    member_attributes = ['managedby']
    takes_options = LDAPSearch.takes_options + (
        Bytes('usercertificate?', validate_certificate,
            cli_name='certificate',
            label=_('Certificate'),
            doc=_('Base-64 encoded server certificate'),
        ),
    )
    def pre_callback(self, ldap, filter, attrs_list, base_dn, *args, **options):
        # lisp style!
        custom_filter = '(&(objectclass=ipaService)' \
                          '(!(objectClass=posixAccount))' \
                          '(!(|(krbprincipalname=kadmin/*)' \
                              '(krbprincipalname=K/M@*)' \
                              '(krbprincipalname=krbtgt/*))' \
                          ')' \
                        ')'
        return ldap.combine_filters(
            (custom_filter, filter), rules=ldap.MATCH_ALL
        )

api.register(service_find)


class service_show(LDAPRetrieve):
    """
    Display service.
    """
    member_attributes = ['managedby']
    takes_options = LDAPRetrieve.takes_options + (
        Bytes('usercertificate?', validate_certificate,
            cli_name='certificate',
            label=_('Certificate'),
            doc=_('Base-64 encoded server certificate'),
        ),
    )
    has_output_params = (
        Flag('has_keytab',
            label=_('Keytab'),
        )
    )

    def post_callback(self, ldap, dn, entry_attrs, *keys, **options):
        if 'krblastpwdchange' in entry_attrs:
            entry_attrs['has_keytab'] = True
            if not options.get('all', False):
                del entry_attrs['krblastpwdchange']
        else:
            entry_attrs['has_keytab'] = False

        return dn

api.register(service_show)

class service_add_host(LDAPAddMember):
    """
    Add hosts that can manage this service.
    """
    member_attributes = ['managedby']

api.register(service_add_host)


class service_remove_host(LDAPRemoveMember):
    """
    Remove hosts that can manage this service.
    """
    member_attributes = ['managedby']

api.register(service_remove_host)


class service_disable(LDAPQuery):
    """
    Disable the kerberos key of this service.
    """
    has_output = output.standard_value
    msg_summary = _('Removed kerberos key from "%(value)s"')

    def execute(self, *keys, **options):
        ldap = self.obj.backend

        dn = self.obj.get_dn(*keys, **options)
        (dn, entry_attrs) = ldap.get_entry(dn, ['krblastpwdchange'])

        if 'krblastpwdchange' not in entry_attrs:
            error_msg = _('Service principal has no kerberos key')
            raise errors.NotFound(reason=error_msg)

        ldap.remove_principal_key(dn)

        return dict(
            result=True,
            value=keys[0],
        )

api.register(service_disable)