else:

            p = perm.Permission.permission_name

        permissions[RK][r_k] = p

    # defaults for repository groups taken from default user permission

    # on given group

    for perm in default_repo_groups_perms:

        rg_k = perm.UserRepoGroupToPerm.group.group_name

        p = perm.Permission.permission_name

        permissions[GK][rg_k] = p

    # defaults for user groups taken from default user permission

    # on given user group

    for perm in default_user_group_perms:

        u_k = perm.UserUserGroupToPerm.user_group.users_group_name

        p = perm.Permission.permission_name

        permissions[UK][u_k] = p

    #======================================================================

    # !! Augment GLOBALS with user permissions if any found !!

    #======================================================================

    # USER GROUPS comes first

    # user group global permissions

    user_perms_from_users_groups = Session().query(UserGroupToPerm) \

        .options(joinedload(UserGroupToPerm.permission)) \

        .join((UserGroupMember, UserGroupToPerm.users_group_id ==

               UserGroupMember.users_group_id)) \

        .filter(UserGroupMember.user_id == user_id) \

        .join((UserGroup, UserGroupMember.users_group_id ==

               UserGroup.users_group_id)) \

        .filter(UserGroup.users_group_active == True) \

        .order_by(UserGroupToPerm.users_group_id) \

        .all()

    # need to group here by groups since user can be in more than

    # one group

    _grouped = [[x, list(y)] for x, y in

                itertools.groupby(user_perms_from_users_groups,

                                  lambda x:x.users_group)]

    for gr, perms in _grouped:

        for perm in perms:

            permissions[GLOBAL].add(perm.permission.permission_name)

    # user specific global permissions

    user_perms = Session().query(UserToPerm) \

            .options(joinedload(UserToPerm.permission)) \

            .filter(UserToPerm.user_id == user_id).all()

    for perm in user_perms:

        permissions[GLOBAL].add(perm.permission.permission_name)

    # for each kind of global permissions, only keep the one with heighest weight

    kind_max_perm = {}

    for perm in sorted(permissions[GLOBAL], key=lambda n: PERM_WEIGHTS[n]):

        kind = perm.rsplit('.', 1)[0]

        kind_max_perm[kind] = perm

    permissions[GLOBAL] = set(kind_max_perm.values())

    ## END GLOBAL PERMISSIONS

    #======================================================================

    # !! PERMISSIONS FOR REPOSITORIES !!

    #======================================================================

    #======================================================================

    # check if user is part of user groups for this repository and

    # fill in his permission from it.

    #======================================================================

    # user group for repositories permissions

    user_repo_perms_from_users_groups = \

     Session().query(UserGroupRepoToPerm, Permission, Repository,) \

        .join((Repository, UserGroupRepoToPerm.repository_id ==

               Repository.repo_id)) \

        .join((Permission, UserGroupRepoToPerm.permission_id ==

               Permission.permission_id)) \

        .join((UserGroup, UserGroupRepoToPerm.users_group_id ==

               UserGroup.users_group_id)) \

        .filter(UserGroup.users_group_active == True) \

        .join((UserGroupMember, UserGroupRepoToPerm.users_group_id ==

               UserGroupMember.users_group_id)) \

        .filter(UserGroupMember.user_id == user_id) \

        .all()

    for perm in user_repo_perms_from_users_groups:

        bump_permission(RK,

            perm.UserGroupRepoToPerm.repository.repo_name,

            perm.Permission.permission_name)

    # user permissions for repositories

    user_repo_perms = Permission.get_default_perms(user_id)

    for perm in user_repo_perms:

        bump_permission(RK,

            perm.UserRepoToPerm.repository.repo_name,

            perm.Permission.permission_name)

    #======================================================================

    # !! PERMISSIONS FOR REPOSITORY GROUPS !!

    #======================================================================

    #======================================================================

    # check if user is part of user groups for this repository groups and

    # fill in his permission from it.

    #======================================================================

    # user group for repo groups permissions

    user_repo_group_perms_from_users_groups = \

     Session().query(UserGroupRepoGroupToPerm, Permission, RepoGroup) \

     .join((RepoGroup, UserGroupRepoGroupToPerm.group_id == RepoGroup.group_id)) \

     .join((Permission, UserGroupRepoGroupToPerm.permission_id

            == Permission.permission_id)) \

     .join((UserGroup, UserGroupRepoGroupToPerm.users_group_id ==

            UserGroup.users_group_id)) \

     .filter(UserGroup.users_group_active == True) \

     .join((UserGroupMember, UserGroupRepoGroupToPerm.users_group_id

            == UserGroupMember.users_group_id)) \

     .filter(UserGroupMember.user_id == user_id) \

     .all()

    for perm in user_repo_group_perms_from_users_groups:

        bump_permission(GK,

            perm.UserGroupRepoGroupToPerm.group.group_name,

            perm.Permission.permission_name)

    # user explicit permissions for repository groups

    user_repo_groups_perms = Permission.get_default_group_perms(user_id)

    for perm in user_repo_groups_perms:

        bump_permission(GK,

            perm.UserRepoGroupToPerm.group.group_name,

            perm.Permission.permission_name)

    #======================================================================

    # !! PERMISSIONS FOR USER GROUPS !!

    #======================================================================

    # user group for user group permissions

    user_group_user_groups_perms = \

     Session().query(UserGroupUserGroupToPerm, Permission, UserGroup) \

     .join((UserGroup, UserGroupUserGroupToPerm.target_user_group_id

            == UserGroup.users_group_id)) \

     .join((Permission, UserGroupUserGroupToPerm.permission_id

            == Permission.permission_id)) \

     .join((UserGroupMember, UserGroupUserGroupToPerm.user_group_id

            == UserGroupMember.users_group_id)) \

     .filter(UserGroupMember.user_id == user_id) \

     .join((UserGroup, UserGroupMember.users_group_id ==

            UserGroup.users_group_id), aliased=True, from_joinpoint=True) \

     .filter(UserGroup.users_group_active == True) \

     .all()

    for perm in user_group_user_groups_perms:

        bump_permission(UK,

            perm.UserGroupUserGroupToPerm.target_user_group.users_group_name,

            perm.Permission.permission_name)

    # user explicit permission for user groups

    user_user_groups_perms = Permission.get_default_user_group_perms(user_id)

    for perm in user_user_groups_perms:

        bump_permission(UK,

            perm.UserUserGroupToPerm.user_group.users_group_name,

            perm.Permission.permission_name)

    return permissions

class AuthUser(object):

    """

    Represents a Kallithea user, including various authentication and

    authorization information. Typically used to store the current user,

    but is also used as a generic user information data structure in

    parts of the code, e.g. user management.

    Constructed from a database `User` object, a user ID or cookie dict,

    it looks up the user (if needed) and copies all attributes to itself,

    adding various non-persistent data. If lookup fails but anonymous

    access to Kallithea is enabled, the default user is loaded instead.

    `AuthUser` does not by itself authenticate users. It's up to other parts of

    the code to check e.g. if a supplied password is correct, and if so, trust

    the AuthUser object as an authenticated user.

    However, `AuthUser` does refuse to load a user that is not `active`.

    Note that Kallithea distinguishes between the default user (an actual

    user in the database with username "default") and "no user" (no actual

    User object, AuthUser filled with blank values and username "None").

    If the default user is active, that will always be used instead of

    "no user". On the other hand, if the default user is disabled (and

    there is no login information), we instead get "no user"; this should

    only happen on the login page (as all other requests are redirected).

    `is_default_user` specifically checks if the AuthUser is the user named

    "default". Use `is_anonymous` to check for both "default" and "no user".

    """

    @classmethod

        """Create an AuthUser to be authenticated ... or return None if user for some reason can't be authenticated.

        Checks that a non-None dbuser is provided, is active, and that the IP address is ok.

        """

        assert ip_addr is not None

        if dbuser is None:

            log.info('No db user for authentication')

            return None

        if not dbuser.active:

            log.info('Db user %s not active', dbuser.username)

            return None

        allowed_ips = AuthUser.get_allowed_ips(dbuser.user_id, cache=True)

        if not check_ip_access(source_ip=ip_addr, allowed_ips=allowed_ips):

            log.info('Access for %s from %s forbidden - not in %s', dbuser.username, ip_addr, allowed_ips)

            return None

        self.is_external_auth = is_external_auth # container auth - don't show logout option

        # These attributes will be overridden by fill_data, below, unless the

        # requested user cannot be found and the default anonymous user is

        # not enabled.

        self.user_id = None

        self.username = None

        self.api_key = None

        self.name = ''

        self.lastname = ''

        self.email = ''

        self.admin = False

        # Look up database user, if necessary.

        if user_id is not None:

            assert dbuser is None

            log.debug('Auth User lookup by USER ID %s', user_id)

            dbuser = UserModel().get(user_id)

            assert dbuser is not None

        else:

            assert dbuser is not None

            log.debug('Auth User lookup by database user %s', dbuser)

        if self._fill_data(dbuser):

            self.is_default_user = dbuser.is_default_user

        else:

            assert dbuser.is_default_user

            assert not self.username

            self.username = 'None'

            self.is_default_user = False

        self.is_anonymous = dbuser.is_default_user

        log.debug('Auth User is now %s', self)

    def _fill_data(self, dbuser):

        """

        Copies database fields from a `db.User` to this `AuthUser`. Does

        not copy `api_keys` and `permissions` attributes.

        Checks that `dbuser` is `active` (and not None) before copying;

        returns True on success.

        """

        if dbuser is not None and dbuser.active:

            log.debug('filling %s data', dbuser)

            for k, v in dbuser.get_dict().iteritems():

                assert k not in ['api_keys', 'permissions']

                setattr(self, k, v)

            return True

        return False

    @LazyProperty

    def permissions(self):

        return self.__get_perms(user=self, cache=False)

    def has_repository_permission_level(self, repo_name, level, purpose=None):

        required_perms = {

            'read': ['repository.read', 'repository.write', 'repository.admin'],

            'write': ['repository.write', 'repository.admin'],

            'admin': ['repository.admin'],

        }[level]

        actual_perm = self.permissions['repositories'].get(repo_name)

        ok = actual_perm in required_perms

        log.debug('Checking if user %r can %r repo %r (%s): %s (has %r)',

            self.username, level, repo_name, purpose, ok, actual_perm)

        return ok

    def has_repository_group_permission_level(self, repo_group_name, level, purpose=None):

        required_perms = {

            'read': ['group.read', 'group.write', 'group.admin'],

            'write': ['group.write', 'group.admin'],

            'admin': ['group.admin'],

        }[level]

        actual_perm = self.permissions['repositories_groups'].get(repo_group_name)

        ok = actual_perm in required_perms

        log.debug('Checking if user %r can %r repo group %r (%s): %s (has %r)',

            self.username, level, repo_group_name, purpose, ok, actual_perm)

        return ok

    def has_user_group_permission_level(self, user_group_name, level, purpose=None):

        required_perms = {

            'read': ['usergroup.read', 'usergroup.write', 'usergroup.admin'],

            'write': ['usergroup.write', 'usergroup.admin'],

            'admin': ['usergroup.admin'],

        }[level]

        actual_perm = self.permissions['user_groups'].get(user_group_name)

        ok = actual_perm in required_perms

        log.debug('Checking if user %r can %r user group %r (%s): %s (has %r)',

            self.username, level, user_group_name, purpose, ok, actual_perm)

        return ok

    @property

    def api_keys(self):

        return self._get_api_keys()

    def __get_perms(self, user, cache=False):

        """

        Fills user permission attribute with permissions taken from database

        works for permissions given for repositories, and for permissions that

        are granted to groups

        :param user: `AuthUser` instance

        """

        user_id = user.user_id

        user_is_admin = user.is_admin

        log.debug('Getting PERMISSION tree')

        compute = conditional_cache('short_term', 'cache_desc',

                                    condition=cache, func=_cached_perms_data)

        return compute(user_id, user_is_admin)

    def _get_api_keys(self):

        api_keys = [self.api_key]

        for api_key in UserApiKeys.query() \

                .filter_by(user_id=self.user_id, is_expired=False):

            api_keys.append(api_key.api_key)

        return api_keys

    @property

    def is_admin(self):

        return self.admin

    @property

    def repositories_admin(self):

        """

        Returns list of repositories you're an admin of

        """

        return [x[0] for x in self.permissions['repositories'].iteritems()

                if x[1] == 'repository.admin']

    @property

    def repository_groups_admin(self):

        """

        Returns list of repository groups you're an admin of

        """

        return [x[0] for x in self.permissions['repositories_groups'].iteritems()

                if x[1] == 'group.admin']

    @property

    def user_groups_admin(self):

        """

        Returns list of user groups you're an admin of

        """

        return [x[0] for x in self.permissions['user_groups'].iteritems()

                if x[1] == 'usergroup.admin']

    def __repr__(self):

        return "<AuthUser('id:%s[%s]')>" % (self.user_id, self.username)

    def to_cookie(self):

        """ Serializes this login session to a cookie `dict`. """

        return {

            'user_id': self.user_id,

            'is_external_auth': self.is_external_auth,

        }

    @staticmethod

    def from_cookie(cookie, ip_addr):

        """

        Deserializes an `AuthUser` from a cookie `dict` ... or return None.

        """

        return AuthUser.make(

            dbuser=UserModel().get(cookie.get('user_id')),

            is_external_auth=cookie.get('is_external_auth', False),

            ip_addr=ip_addr,

        )

    @classmethod

    def get_allowed_ips(cls, user_id, cache=False):

        _set = set()

        default_ips = UserIpMap.query().filter(UserIpMap.user_id ==

                                        User.get_default_user(cache=True).user_id)

        if cache:

            default_ips = default_ips.options(FromCache("sql_cache_short",

                                              "get_user_ips_default"))

        for ip in default_ips:

            try:

                _set.add(ip.ip_addr)

            except ObjectDeletedError:

                # since we use heavy caching sometimes it happens that we get

                # deleted objects here, we just skip them

                pass

        user_ips = UserIpMap.query().filter(UserIpMap.user_id == user_id)

        if cache:

            user_ips = user_ips.options(FromCache("sql_cache_short",

                                                  "get_user_ips_%s" % user_id))

        for ip in user_ips:

            try:

                _set.add(ip.ip_addr)

            except ObjectDeletedError:

                # since we use heavy caching sometimes it happens that we get

                                              'repository.admin')(authuser,

                                                                  repo_name):

                return False

        else:

            #any other action need at least read permission

            if not HasPermissionAnyMiddleware('repository.read',

                                              'repository.write',

                                              'repository.admin')(authuser,

                                                                  repo_name):

                return False

        return True

    def _get_ip_addr(self, environ):

        return _get_ip_addr(environ)

    def __call__(self, environ, start_response):

        start = time.time()

        try:

            return self._handle_request(environ, start_response)

        finally:

            log = logging.getLogger('kallithea.' + self.__class__.__name__)

            log.debug('Request time: %.3fs', time.time() - start)

            meta.Session.remove()

class BaseController(TGController):

    def _before(self, *args, **kwargs):

        """

        _before is called before controller methods and after __call__

        """

        if request.needs_csrf_check:

            # CSRF protection: Whenever a request has ambient authority (whether

            # through a session cookie or its origin IP address), it must include

            # the correct token, unless the HTTP method is GET or HEAD (and thus

            # guaranteed to be side effect free. In practice, the only situation

            # where we allow side effects without ambient authority is when the

            # authority comes from an API key; and that is handled above.

            token = request.POST.get(secure_form.token_key)

            if not token or token != secure_form.authentication_token():

                log.error('CSRF check failed')

                raise webob.exc.HTTPForbidden()

        c.kallithea_version = __version__

        rc_config = Setting.get_app_settings()

        # Visual options

        c.visual = AttributeDict({})

        ## DB stored

        c.visual.show_public_icon = str2bool(rc_config.get('show_public_icon'))

        c.visual.show_private_icon = str2bool(rc_config.get('show_private_icon'))

        c.visual.stylify_metalabels = str2bool(rc_config.get('stylify_metalabels'))

        c.visual.page_size = safe_int(rc_config.get('dashboard_items', 100))

        c.visual.admin_grid_items = safe_int(rc_config.get('admin_grid_items', 100))

        c.visual.repository_fields = str2bool(rc_config.get('repository_fields'))

        c.visual.show_version = str2bool(rc_config.get('show_version'))

        c.visual.use_gravatar = str2bool(rc_config.get('use_gravatar'))

        c.visual.gravatar_url = rc_config.get('gravatar_url')

        c.ga_code = rc_config.get('ga_code')

        # TODO: replace undocumented backwards compatibility hack with db upgrade and rename ga_code

        if c.ga_code and '<' not in c.ga_code:

            c.ga_code = '''<script type="text/javascript">

                var _gaq = _gaq || [];

                _gaq.push(['_setAccount', '%s']);

                _gaq.push(['_trackPageview']);

                (function() {

                    var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;

                    ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';

                    var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);

                    })();

            </script>''' % c.ga_code

        c.site_name = rc_config.get('title')

        c.clone_uri_tmpl = rc_config.get('clone_uri_tmpl')

        ## INI stored

        c.visual.allow_repo_location_change = str2bool(config.get('allow_repo_location_change', True))

        c.visual.allow_custom_hooks_settings = str2bool(config.get('allow_custom_hooks_settings', True))

        c.instance_id = config.get('instance_id')

        c.issues_url = config.get('bugtracker', url('issues_url'))

        # END CONFIG VARS

        c.repo_name = get_repo_slug(request)  # can be empty

        c.backends = BACKENDS.keys()

        self.cut_off_limit = safe_int(config.get('cut_off_limit'))

        c.my_pr_count = PullRequest.query(reviewer_id=request.authuser.user_id, include_closed=False).count()

        self.scm_model = ScmModel()

    @staticmethod

    def _determine_auth_user(session_authuser, ip_addr):

        """

        Create an `AuthUser` object given the API key/bearer token

        (if any) and the value of the authuser session cookie.

        Returns None if no valid user is found (like not active or no access for IP).

        """

        # Authenticate by session cookie

        # In ancient login sessions, 'authuser' may not be a dict.

        # In that case, the user will have to log in again.

        # v0.3 and earlier included an 'is_authenticated' key; if present,

        # this must be True.

        if isinstance(session_authuser, dict) and session_authuser.get('is_authenticated', True):

            return AuthUser.from_cookie(session_authuser, ip_addr=ip_addr)

        # Authenticate by auth_container plugin (if enabled)

        if any(

            plugin.is_container_auth

            for plugin in auth_modules.get_auth_plugins()

        ):

            try:

                user_info = auth_modules.authenticate('', '', request.environ)

            except UserCreationError as e:

                from kallithea.lib import helpers as h

                h.flash(e, 'error', logf=log.error)

            else:

                if user_info is not None:

                    username = user_info['username']

                    user = User.get_by_username(username, case_insensitive=True)

                    return log_in_user(user, remember=False, is_external_auth=True, ip_addr=ip_addr)

        # User is default user (if active) or anonymous

        default_user = User.get_default_user(cache=True)

        authuser = AuthUser.make(dbuser=default_user, ip_addr=ip_addr)

        if authuser is None: # fall back to anonymous

            authuser = AuthUser(dbuser=default_user) # TODO: somehow use .make?

        return authuser

    @staticmethod

    def _basic_security_checks():

        """Perform basic security/sanity checks before processing the request."""

        # Only allow the following HTTP request methods.

        if request.method not in ['GET', 'HEAD', 'POST']:

            raise webob.exc.HTTPMethodNotAllowed()

        # Also verify the _method override - no longer allowed.

        if request.params.get('_method') is None:

            pass # no override, no problem

        else:

            raise webob.exc.HTTPMethodNotAllowed()

        # Make sure CSRF token never appears in the URL. If so, invalidate it.

        if secure_form.token_key in request.GET:

            log.error('CSRF key leak detected')

            session.pop(secure_form.token_key, None)

            session.save()

            from kallithea.lib import helpers as h

            h.flash(_('CSRF token leak has been detected - all form tokens have been expired'),

                    category='error')

        # WebOb already ignores request payload parameters for anything other

        # than POST/PUT, but double-check since other Kallithea code relies on

        # this assumption.

        if request.method not in ['POST', 'PUT'] and request.POST:

            log.error('%r request with payload parameters; WebOb should have stopped this', request.method)

            raise webob.exc.HTTPBadRequest()

    def __call__(self, environ, context):

        try:

            ip_addr = _get_ip_addr(environ)

            self._basic_security_checks()

            api_key = request.GET.get('api_key')

            try:

                # Request.authorization may raise ValueError on invalid input

                type, params = request.authorization

            except (ValueError, TypeError):

                pass

            else:

                if type.lower() == 'bearer':

                    api_key = params # bearer token is an api key too

            if api_key is None:

                authuser = self._determine_auth_user(

                    session.get('authuser'),

                    ip_addr=ip_addr,

                )

                needs_csrf_check = request.method not in ['GET', 'HEAD']

            else:

                dbuser = User.get_by_api_key(api_key)

                if dbuser is None:

                    log.info('No db user found for authentication with API key ****%s from %s',

                             api_key[-4:], ip_addr)

                needs_csrf_check = False # API key provides CSRF protection

            if authuser is None:

                log.info('No valid user found')

                raise webob.exc.HTTPForbidden()

            # set globals for auth user

            request.authuser = authuser

            request.ip_addr = ip_addr

            request.needs_csrf_check = needs_csrf_check

            log.info('IP: %s User: %s accessed %s',

                request.ip_addr, request.authuser,

                safe_unicode(_get_access_path(environ)),

            )

            return super(BaseController, self).__call__(environ, context)

        except webob.exc.HTTPException as e:

            return e

class BaseRepoController(BaseController):

    """

    Base class for controllers responsible for loading all needed data for

    repository loaded items are

    c.db_repo_scm_instance: instance of scm repository

    c.db_repo: instance of db

    c.repository_followers: number of followers

    c.repository_forks: number of forks

    c.repository_following: weather the current user is following the current repo

    """

    def _before(self, *args, **kwargs):

        super(BaseRepoController, self)._before(*args, **kwargs)

        if c.repo_name:  # extracted from routes

            _dbr = Repository.get_by_repo_name(c.repo_name)

            if not _dbr:

                return

            log.debug('Found repository in database %s with state `%s`',

                      safe_unicode(_dbr), safe_unicode(_dbr.repo_state))

            route = getattr(request.environ.get('routes.route'), 'name', '')

            # allow to delete repos that are somehow damages in filesystem

            if route in ['delete_repo']:

                return

            if _dbr.repo_state in [Repository.STATE_PENDING]:

                if route in ['repo_creating_home']:

                    return

                check_url = url('repo_creating_home', repo_name=c.repo_name)

                raise webob.exc.HTTPFound(location=check_url)

            dbr = c.db_repo = _dbr

            c.db_repo_scm_instance = c.db_repo.scm_instance

            if c.db_repo_scm_instance is None:

                log.error('%s this repository is present in database but it '

                          'cannot be created as an scm instance', c.repo_name)

                from kallithea.lib import helpers as h

                h.flash(_('Repository not found in the filesystem'),

                        category='error')

                raise webob.exc.HTTPNotFound()

            # some globals counter for menu

            c.repository_followers = self.scm_model.get_followers(dbr)

            c.repository_forks = self.scm_model.get_forks(dbr)

            c.repository_pull_requests = self.scm_model.get_pull_requests(dbr)

            c.repository_following = self.scm_model.is_following_repo(

                                    c.repo_name, request.authuser.user_id)

    @staticmethod

    def _get_ref_rev(repo, ref_type, ref_name, returnempty=False):

        """

        Safe way to get changeset. If error occurs show error.

        """

        from kallithea.lib import helpers as h

        try:

            return repo.scm_instance.get_ref_revision(ref_type, ref_name)

        except EmptyRepositoryError as e:

            if returnempty:

                return repo.scm_instance.EMPTY_CHANGESET

            h.flash(_('There are no changesets yet'), category='error')

            raise webob.exc.HTTPNotFound()

        except ChangesetDoesNotExistError as e:

            h.flash(_('Changeset for %s %s not found in %s') %

                              (ref_type, ref_name, repo.repo_name),

                    category='error')

            raise webob.exc.HTTPNotFound()

        except RepositoryError as e:

            log.error(traceback.format_exc())

            h.flash(safe_str(e), category='error')

            raise webob.exc.HTTPBadRequest()

@decorator.decorator

def jsonify(func, *args, **kwargs):

    """Action decorator that formats output for JSON

    Given a function that will return content, this decorator will turn

    the result into JSON, with a content-type of 'application/json' and

    output it.

    """

    response.headers['Content-Type'] = 'application/json; charset=utf-8'

    data = func(*args, **kwargs)

    if isinstance(data, (list, tuple)):

        # A JSON list response is syntactically valid JavaScript and can be

        # loaded and executed as JavaScript by a malicious third-party site

        # using <script>, which can lead to cross-site data leaks.

        # JSON responses should therefore be scalars or objects (i.e. Python

        # dicts), because a JSON object is a syntax error if intepreted as JS.

        msg = "JSON responses with Array envelopes are susceptible to " \

              "cross-site data leak attacks, see " \

              "https://web.archive.org/web/20120519231904/http://wiki.pylonshq.com/display/pylonsfaq/Warnings"

        warnings.warn(msg, Warning, 2)

        log.warning(msg)

    log.debug("Returning JSON wrapped action output")

    return json.dumps(data, encoding='utf-8')