validator: fix ASCII password check to verify if it can be *encoded* in ascii

In Python 2, unicode strings have a .decode method (which really doesn't make
sense). Python 3 has more strict typing by design, and unicode strings don't
have a .decode method.

A Unicode string "is ASCII" if it can be encoded as ASCII. The check should
thus *encode* to ASCII - not decode.

kallithea/model/validators.py

@@ -1,804 +1,804 b''
 # -*- coding: utf-8 -*-
 # 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 3 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/>.
 """
 Set of generic validators
 """
 
 import logging
 import os
 import re
 from collections import defaultdict
 
 import formencode
 import ipaddr
 import sqlalchemy
 from formencode.validators import CIDR, Bool, Email, FancyValidator, Int, IPAddress, NotEmpty, Number, OneOf, Regex, Set, String, StringBoolean, UnicodeString
 from sqlalchemy import func
 from tg.i18n import ugettext as _
 
 from kallithea.config.routing import ADMIN_PREFIX
 from kallithea.lib.auth import HasPermissionAny, HasRepoGroupPermissionLevel
 from kallithea.lib.compat import OrderedSet
 from kallithea.lib.exceptions import LdapImportError
 from kallithea.lib.utils import is_valid_repo_uri
 from kallithea.lib.utils2 import aslist, repo_name_slug, str2bool
 from kallithea.model.db import RepoGroup, Repository, User, UserGroup
 
 
 # silence warnings and pylint
 UnicodeString, OneOf, Int, Number, Regex, Email, Bool, StringBoolean, Set, \
     NotEmpty, IPAddress, CIDR, String, FancyValidator
 
 log = logging.getLogger(__name__)
 
 
 def UniqueListFromString():
     class _UniqueListFromString(formencode.FancyValidator):
         """
         Split value on ',' and make unique while preserving order
         """
         messages = dict(
             empty=_('Value cannot be an empty list'),
             missing_value=_('Value cannot be an empty list'),
         )
 
         def _convert_to_python(self, value, state):
             value = aslist(value, ',')
             seen = set()
             return [c for c in value if not (c in seen or seen.add(c))]
 
         def empty_value(self, value):
             return []
 
     return _UniqueListFromString
 
 
 def ValidUsername(edit=False, old_data=None):
     old_data = old_data or {}
 
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'username_exists': _('Username "%(username)s" already exists'),
             'system_invalid_username':
                 _('Username "%(username)s" cannot be used'),
             'invalid_username':
                 _('Username may only contain alphanumeric characters '
                   'underscores, periods or dashes and must begin with an '
                   'alphanumeric character or underscore')
         }
 
         def _validate_python(self, value, state):
             if value in ['default', 'new_user']:
                 msg = self.message('system_invalid_username', state, username=value)
                 raise formencode.Invalid(msg, value, state)
             # check if user is unique
             old_un = None
             if edit:
                 old_un = User.get(old_data.get('user_id')).username
 
             if old_un != value or not edit:
                 if User.get_by_username(value, case_insensitive=True):
                     msg = self.message('username_exists', state, username=value)
                     raise formencode.Invalid(msg, value, state)
 
             if re.match(r'^[a-zA-Z0-9\_]{1}[a-zA-Z0-9\-\_\.]*$', value) is None:
                 msg = self.message('invalid_username', state)
                 raise formencode.Invalid(msg, value, state)
     return _validator
 
 
 def ValidRegex(msg=None):
     class _validator(formencode.validators.Regex):
         messages = dict(invalid=msg or _('The input is not valid'))
     return _validator
 
 
 def ValidRepoUser():
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'invalid_username': _('Username %(username)s is not valid')
         }
 
         def _validate_python(self, value, state):
             try:
                 User.query().filter(User.active == True) \
                     .filter(User.username == value).one()
             except sqlalchemy.exc.InvalidRequestError: # NoResultFound/MultipleResultsFound
                 msg = self.message('invalid_username', state, username=value)
                 raise formencode.Invalid(msg, value, state,
                     error_dict=dict(username=msg)
                 )
 
     return _validator
 
 
 def ValidUserGroup(edit=False, old_data=None):
     old_data = old_data or {}
 
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'invalid_group': _('Invalid user group name'),
             'group_exist': _('User group "%(usergroup)s" already exists'),
             'invalid_usergroup_name':
                 _('user group name may only contain alphanumeric '
                   'characters underscores, periods or dashes and must begin '
                   'with alphanumeric character')
         }
 
         def _validate_python(self, value, state):
             if value in ['default']:
                 msg = self.message('invalid_group', state)
                 raise formencode.Invalid(msg, value, state,
                     error_dict=dict(users_group_name=msg)
                 )
             # check if group is unique
             old_ugname = None
             if edit:
                 old_id = old_data.get('users_group_id')
                 old_ugname = UserGroup.get(old_id).users_group_name
 
             if old_ugname != value or not edit:
                 is_existing_group = UserGroup.get_by_group_name(value,
                                                         case_insensitive=True)
                 if is_existing_group:
                     msg = self.message('group_exist', state, usergroup=value)
                     raise formencode.Invalid(msg, value, state,
                         error_dict=dict(users_group_name=msg)
                     )
 
             if re.match(r'^[a-zA-Z0-9]{1}[a-zA-Z0-9\-\_\.]+$', value) is None:
                 msg = self.message('invalid_usergroup_name', state)
                 raise formencode.Invalid(msg, value, state,
                     error_dict=dict(users_group_name=msg)
                 )
 
     return _validator
 
 
 def ValidRepoGroup(edit=False, old_data=None):
     old_data = old_data or {}
 
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'parent_group_id': _('Cannot assign this group as parent'),
             'group_exists': _('Group "%(group_name)s" already exists'),
             'repo_exists':
                 _('Repository with name "%(group_name)s" already exists')
         }
 
         def _validate_python(self, value, state):
             # TODO WRITE VALIDATIONS
             group_name = value.get('group_name')
             parent_group_id = value.get('parent_group_id')
 
             # slugify repo group just in case :)
             slug = repo_name_slug(group_name)
 
             # check for parent of self
             parent_of_self = lambda: (
                 old_data['group_id'] == parent_group_id
                 if parent_group_id else False
             )
             if edit and parent_of_self():
                 msg = self.message('parent_group_id', state)
                 raise formencode.Invalid(msg, value, state,
                     error_dict=dict(parent_group_id=msg)
                 )
 
             old_gname = None
             if edit:
                 old_gname = RepoGroup.get(old_data.get('group_id')).group_name
 
             if old_gname != group_name or not edit:
 
                 # check group
                 gr = RepoGroup.query() \
                       .filter(func.lower(RepoGroup.group_name) == func.lower(slug)) \
                       .filter(RepoGroup.parent_group_id == parent_group_id) \
                       .scalar()
                 if gr is not None:
                     msg = self.message('group_exists', state, group_name=slug)
                     raise formencode.Invalid(msg, value, state,
                             error_dict=dict(group_name=msg)
                     )
 
                 # check for same repo
                 repo = Repository.query() \
                       .filter(func.lower(Repository.repo_name) == func.lower(slug)) \
                       .scalar()
                 if repo is not None:
                     msg = self.message('repo_exists', state, group_name=slug)
                     raise formencode.Invalid(msg, value, state,
                             error_dict=dict(group_name=msg)
                     )
 
     return _validator
 
 
 def ValidPassword():
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'invalid_password':
                 _('Invalid characters (non-ascii) in password')
         }
 
         def _validate_python(self, value, state):
             try:
-                (value or '').decode('ascii')
+                (value or '').encode('ascii')
             except UnicodeError:
                 msg = self.message('invalid_password', state)
                 raise formencode.Invalid(msg, value, state,)
     return _validator
 
 
 def ValidOldPassword(username):
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'invalid_password': _('Invalid old password')
         }
 
         def _validate_python(self, value, state):
             from kallithea.lib import auth_modules
             if auth_modules.authenticate(username, value, '') is None:
                 msg = self.message('invalid_password', state)
                 raise formencode.Invalid(msg, value, state,
                     error_dict=dict(current_password=msg)
                 )
     return _validator
 
 
 def ValidPasswordsMatch(password_field, password_confirmation_field):
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'password_mismatch': _('Passwords do not match'),
         }
 
         def _validate_python(self, value, state):
             if value.get(password_field) != value[password_confirmation_field]:
                 msg = self.message('password_mismatch', state)
                 raise formencode.Invalid(msg, value, state,
                      error_dict={password_field: msg, password_confirmation_field: msg}
                 )
     return _validator
 
 
 def ValidAuth():
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'invalid_auth': _(u'Invalid username or password'),
         }
 
         def _validate_python(self, value, state):
             from kallithea.lib import auth_modules
 
             password = value['password']
             username = value['username']
 
             # authenticate returns unused dict but has called
             # plugin._authenticate which has create_or_update'ed the username user in db
             if auth_modules.authenticate(username, password) is None:
                 user = User.get_by_username_or_email(username)
                 if user and not user.active:
                     log.warning('user %s is disabled', username)
                     msg = self.message('invalid_auth', state)
                     raise formencode.Invalid(msg, value, state,
                         error_dict=dict(username=' ', password=msg)
                     )
                 else:
                     log.warning('user %s failed to authenticate', username)
                     msg = self.message('invalid_auth', state)
                     raise formencode.Invalid(msg, value, state,
                         error_dict=dict(username=' ', password=msg)
                     )
     return _validator
 
 
 def ValidRepoName(edit=False, old_data=None):
     old_data = old_data or {}
 
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'invalid_repo_name':
                 _('Repository name %(repo)s is not allowed'),
             'repository_exists':
                 _('Repository named %(repo)s already exists'),
             'repository_in_group_exists': _('Repository "%(repo)s" already '
                                             'exists in group "%(group)s"'),
             'same_group_exists': _('Repository group with name "%(repo)s" '
                                    'already exists')
         }
 
         def _convert_to_python(self, value, state):
             repo_name = repo_name_slug(value.get('repo_name', ''))
             repo_group = value.get('repo_group')
             if repo_group:
                 gr = RepoGroup.get(repo_group)
                 group_path = gr.full_path
                 group_name = gr.group_name
                 # value needs to be aware of group name in order to check
                 # db key This is an actual just the name to store in the
                 # database
                 repo_name_full = group_path + RepoGroup.url_sep() + repo_name
             else:
                 group_name = group_path = ''
                 repo_name_full = repo_name
 
             value['repo_name'] = repo_name
             value['repo_name_full'] = repo_name_full
             value['group_path'] = group_path
             value['group_name'] = group_name
             return value
 
         def _validate_python(self, value, state):
             repo_name = value.get('repo_name')
             repo_name_full = value.get('repo_name_full')
             group_path = value.get('group_path')
             group_name = value.get('group_name')
 
             if repo_name in [ADMIN_PREFIX, '']:
                 msg = self.message('invalid_repo_name', state, repo=repo_name)
                 raise formencode.Invalid(msg, value, state,
                     error_dict=dict(repo_name=msg)
                 )
 
             rename = old_data.get('repo_name') != repo_name_full
             create = not edit
             if rename or create:
                 repo = Repository.get_by_repo_name(repo_name_full, case_insensitive=True)
                 repo_group = RepoGroup.get_by_group_name(repo_name_full, case_insensitive=True)
                 if group_path != '':
                     if repo is not None:
                         msg = self.message('repository_in_group_exists', state,
                                 repo=repo.repo_name, group=group_name)
                         raise formencode.Invalid(msg, value, state,
                             error_dict=dict(repo_name=msg)
                         )
                 elif repo_group is not None:
                     msg = self.message('same_group_exists', state,
                             repo=repo_name)
                     raise formencode.Invalid(msg, value, state,
                         error_dict=dict(repo_name=msg)
                     )
                 elif repo is not None:
                     msg = self.message('repository_exists', state,
                             repo=repo.repo_name)
                     raise formencode.Invalid(msg, value, state,
                         error_dict=dict(repo_name=msg)
                     )
             return value
     return _validator
 
 
 def ValidForkName(*args, **kwargs):
     return ValidRepoName(*args, **kwargs)
 
 
 def SlugifyName():
     class _validator(formencode.validators.FancyValidator):
 
         def _convert_to_python(self, value, state):
             return repo_name_slug(value)
 
         def _validate_python(self, value, state):
             pass
 
     return _validator
 
 
 def ValidCloneUri():
     from kallithea.lib.utils import make_ui
 
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'clone_uri': _('Invalid repository URL'),
             'invalid_clone_uri': _('Invalid repository URL. It must be a '
                                    'valid http, https, ssh, svn+http or svn+https URL'),
         }
 
         def _validate_python(self, value, state):
             repo_type = value.get('repo_type')
             url = value.get('clone_uri')
 
             if url and url != value.get('clone_uri_hidden'):
                 try:
                     is_valid_repo_uri(repo_type, url, make_ui())
                 except Exception:
                     log.exception('URL validation failed')
                     msg = self.message('clone_uri', state)
                     raise formencode.Invalid(msg, value, state,
                         error_dict=dict(clone_uri=msg)
                     )
     return _validator
 
 
 def ValidForkType(old_data=None):
     old_data = old_data or {}
 
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'invalid_fork_type': _('Fork has to be the same type as parent')
         }
 
         def _validate_python(self, value, state):
             if old_data['repo_type'] != value:
                 msg = self.message('invalid_fork_type', state)
                 raise formencode.Invalid(msg, value, state,
                     error_dict=dict(repo_type=msg)
                 )
     return _validator
 
 
 def CanWriteGroup(old_data=None):
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'permission_denied': _("You don't have permissions "
                                    "to create repository in this group"),
             'permission_denied_root': _("no permission to create repository "
                                         "in root location")
         }
 
         def _convert_to_python(self, value, state):
             # root location
             if value == -1:
                 return None
             return value
 
         def _validate_python(self, value, state):
             gr = RepoGroup.get(value)
             gr_name = gr.group_name if gr is not None else None # None means ROOT location
 
             # create repositories with write permission on group is set to true
             create_on_write = HasPermissionAny('hg.create.write_on_repogroup.true')()
             group_admin = HasRepoGroupPermissionLevel('admin')(gr_name,
                                             'can write into group validator')
             group_write = HasRepoGroupPermissionLevel('write')(gr_name,
                                             'can write into group validator')
             forbidden = not (group_admin or (group_write and create_on_write))
             can_create_repos = HasPermissionAny('hg.admin', 'hg.create.repository')
             gid = (old_data['repo_group'].get('group_id')
                    if (old_data and 'repo_group' in old_data) else None)
             value_changed = gid != value
             new = not old_data
             # do check if we changed the value, there's a case that someone got
             # revoked write permissions to a repository, he still created, we
             # don't need to check permission if he didn't change the value of
             # groups in form box
             if value_changed or new:
                 # parent group need to be existing
                 if gr and forbidden:
                     msg = self.message('permission_denied', state)
                     raise formencode.Invalid(msg, value, state,
                         error_dict=dict(repo_type=msg)
                     )
                 ## check if we can write to root location !
                 elif gr is None and not can_create_repos():
                     msg = self.message('permission_denied_root', state)
                     raise formencode.Invalid(msg, value, state,
                         error_dict=dict(repo_type=msg)
                     )
 
     return _validator
 
 
 def CanCreateGroup(can_create_in_root=False):
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'permission_denied': _("You don't have permissions "
                                    "to create a group in this location")
         }
 
         def to_python(self, value, state):
             # root location
             if value == -1:
                 return None
             return value
 
         def _validate_python(self, value, state):
             gr = RepoGroup.get(value)
             gr_name = gr.group_name if gr is not None else None # None means ROOT location
 
             if can_create_in_root and gr is None:
                 # we can create in root, we're fine no validations required
                 return
 
             forbidden_in_root = gr is None and not can_create_in_root
             forbidden = not HasRepoGroupPermissionLevel('admin')(gr_name, 'can create group validator')
             if forbidden_in_root or forbidden:
                 msg = self.message('permission_denied', state)
                 raise formencode.Invalid(msg, value, state,
                     error_dict=dict(parent_group_id=msg)
                 )
 
     return _validator
 
 
 def ValidPerms(type_='repo'):
     if type_ == 'repo_group':
         EMPTY_PERM = 'group.none'
     elif type_ == 'repo':
         EMPTY_PERM = 'repository.none'
     elif type_ == 'user_group':
         EMPTY_PERM = 'usergroup.none'
 
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'perm_new_member_name':
                 _('This username or user group name is not valid')
         }
 
         def to_python(self, value, state):
             perms_update = OrderedSet()
             perms_new = OrderedSet()
             # build a list of permission to update and new permission to create
 
             # CLEAN OUT ORG VALUE FROM NEW MEMBERS, and group them using
             new_perms_group = defaultdict(dict)
             for k, v in value.copy().iteritems():
                 if k.startswith('perm_new_member'):
                     del value[k]
                     _type, part = k.split('perm_new_member_')
                     args = part.split('_')
                     if len(args) == 1:
                         new_perms_group[args[0]]['perm'] = v
                     elif len(args) == 2:
                         _key, pos = args
                         new_perms_group[pos][_key] = v
 
             # fill new permissions in order of how they were added
             for k in sorted(new_perms_group, key=lambda k: int(k)):
                 perm_dict = new_perms_group[k]
                 new_member = perm_dict.get('name')
                 new_perm = perm_dict.get('perm')
                 new_type = perm_dict.get('type')
                 if new_member and new_perm and new_type:
                     perms_new.add((new_member, new_perm, new_type))
 
             for k, v in value.iteritems():
                 if k.startswith('u_perm_') or k.startswith('g_perm_'):
                     member = k[7:]
                     t = {'u': 'user',
                          'g': 'users_group'
                     }[k[0]]
                     if member == User.DEFAULT_USER:
                         if str2bool(value.get('repo_private')):
                             # set none for default when updating to
                             # private repo protects against form manipulation
                             v = EMPTY_PERM
                     perms_update.add((member, v, t))
 
             value['perms_updates'] = list(perms_update)
             value['perms_new'] = list(perms_new)
 
             # update permissions
             for k, v, t in perms_new:
                 try:
                     if t == 'user':
                         self.user_db = User.query() \
                             .filter(User.active == True) \
                             .filter(User.username == k).one()
                     if t == 'users_group':
                         self.user_db = UserGroup.query() \
                             .filter(UserGroup.users_group_active == True) \
                             .filter(UserGroup.users_group_name == k).one()
 
                 except Exception:
                     log.exception('Updated permission failed')
                     msg = self.message('perm_new_member_type', state)
                     raise formencode.Invalid(msg, value, state,
                         error_dict=dict(perm_new_member_name=msg)
                     )
             return value
     return _validator
 
 
 def ValidSettings():
     class _validator(formencode.validators.FancyValidator):
         def _convert_to_python(self, value, state):
             # settings  form for users that are not admin
             # can't edit certain parameters, it's extra backup if they mangle
             # with forms
 
             forbidden_params = [
                 'user', 'repo_type',
                 'repo_enable_downloads', 'repo_enable_statistics'
             ]
 
             for param in forbidden_params:
                 if param in value:
                     del value[param]
             return value
 
         def _validate_python(self, value, state):
             pass
     return _validator
 
 
 def ValidPath():
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'invalid_path': _('This is not a valid path')
         }
 
         def _validate_python(self, value, state):
             if not os.path.isdir(value):
                 msg = self.message('invalid_path', state)
                 raise formencode.Invalid(msg, value, state,
                     error_dict=dict(paths_root_path=msg)
                 )
     return _validator
 
 
 def UniqSystemEmail(old_data=None):
     old_data = old_data or {}
 
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'email_taken': _('This email address is already in use')
         }
 
         def _convert_to_python(self, value, state):
             return value.lower()
 
         def _validate_python(self, value, state):
             if (old_data.get('email') or '').lower() != value:
                 user = User.get_by_email(value)
                 if user is not None:
                     msg = self.message('email_taken', state)
                     raise formencode.Invalid(msg, value, state,
                         error_dict=dict(email=msg)
                     )
     return _validator
 
 
 def ValidSystemEmail():
     class _validator(formencode.validators.FancyValidator):
         messages = {
             'non_existing_email': _('Email address "%(email)s" not found')
         }
 
         def _convert_to_python(self, value, state):
             return value.lower()
 
         def _validate_python(self, value, state):
             user = User.get_by_email(value)
             if user is None:
                 msg = self.message('non_existing_email', state, email=value)
                 raise formencode.Invalid(msg, value, state,
                     error_dict=dict(email=msg)
                 )
 
     return _validator
 
 
 def LdapLibValidator():
     class _validator(formencode.validators.FancyValidator):
         messages = {
 
         }
 
         def _validate_python(self, value, state):
             try:
                 import ldap
                 ldap  # pyflakes silence !
             except ImportError:
                 raise LdapImportError()
 
     return _validator
 
 
 def AttrLoginValidator():
     class _validator(formencode.validators.UnicodeString):
         messages = {
             'invalid_cn':
                   _('The LDAP Login attribute of the CN must be specified - '
                     'this is the name of the attribute that is equivalent '
                     'to "username"')
         }
         messages['empty'] = messages['invalid_cn']
 
     return _validator
 
 
 def ValidIp():
     class _validator(CIDR):
         messages = dict(
             badFormat=_('Please enter a valid IPv4 or IPv6 address'),
             illegalBits=_('The network size (bits) must be within the range'
                 ' of 0-32 (not %(bits)r)')
         )
 
         def to_python(self, value, state):
             v = super(_validator, self).to_python(value, state)
             v = v.strip()
             net = ipaddr.IPNetwork(address=v)
             if isinstance(net, ipaddr.IPv4Network):
                 # if IPv4 doesn't end with a mask, add /32
                 if '/' not in value:
                     v += '/32'
             if isinstance(net, ipaddr.IPv6Network):
                 # if IPv6 doesn't end with a mask, add /128
                 if '/' not in value:
                     v += '/128'
             return v
 
         def _validate_python(self, value, state):
             try:
                 addr = value.strip()
                 # this raises an ValueError if address is not IPv4 or IPv6
                 ipaddr.IPNetwork(address=addr)
             except ValueError:
                 raise formencode.Invalid(self.message('badFormat', state),
                                          value, state)
 
     return _validator
 
 
 def FieldKey():
     class _validator(formencode.validators.FancyValidator):
         messages = dict(
             badFormat=_('Key name can only consist of letters, '
                         'underscore, dash or numbers')
         )
 
         def _validate_python(self, value, state):
             if not re.match('[a-zA-Z0-9_-]+$', value):
                 raise formencode.Invalid(self.message('badFormat', state),
                                          value, state)
     return _validator
 
 
 def BasePath():
     class _validator(formencode.validators.FancyValidator):
         messages = dict(
             badPath=_('Filename cannot be inside a directory')
         )
 
         def _convert_to_python(self, value, state):
             return value
 
         def _validate_python(self, value, state):
             if value != os.path.basename(value):
                 raise formencode.Invalid(self.message('badPath', state),
                                          value, state)
     return _validator
 
 
 def ValidAuthPlugins():
     class _validator(formencode.validators.FancyValidator):
         messages = dict(
             import_duplicate=_('Plugins %(loaded)s and %(next_to_load)s both export the same name')
         )
 
         def _convert_to_python(self, value, state):
             # filter empty values
             return [s for s in value if s not in [None, '']]
 
         def _validate_python(self, value, state):
             from kallithea.lib import auth_modules
             module_list = value
             unique_names = {}
             try:
                 for module in module_list:
                     plugin = auth_modules.loadplugin(module)
                     plugin_name = plugin.name
                     if plugin_name in unique_names:
                         msg = self.message('import_duplicate', state,
                                 loaded=unique_names[plugin_name],
                                 next_to_load=plugin_name)
                         raise formencode.Invalid(msg, value, state)
                     unique_names[plugin_name] = plugin
             except (ImportError, AttributeError, TypeError) as e:
                 raise formencode.Invalid(str(e), value, state)
 
     return _validator