evennia/evennia/locks/lockfuncs.py

"""
This module provides a set of permission lock functions for use
with Evennia's permissions system.

To call these locks, make sure this module is included in the
settings tuple `PERMISSION_FUNC_MODULES` then define a lock on the form
'<access_type>:func(args)' and add it to the object's lockhandler.
Run the `access()` method of the handler to execute the lock check.

Note that `accessing_obj` and `accessed_obj` can be any object type
with a lock variable/field, so be careful to not expect
a certain object type.

"""


from ast import literal_eval

from django.conf import settings

from evennia.utils import utils

_PERMISSION_HIERARCHY = [pe.lower() for pe in settings.PERMISSION_HIERARCHY]
# also accept different plural forms
_PERMISSION_HIERARCHY_PLURAL = [
    pe + "s" if not pe.endswith("s") else pe for pe in _PERMISSION_HIERARCHY
]


def _to_account(accessing_obj):
    "Helper function. Makes sure an accessing object is an account object"
    if utils.inherits_from(accessing_obj, "evennia.objects.objects.DefaultObject"):
        # an object. Convert to account.
        accessing_obj = accessing_obj.account
    return accessing_obj


# lock functions


def true(*args, **kwargs):
    """
    Always returns True.

    """
    return True


def all(*args, **kwargs):
    return True


def false(*args, **kwargs):
    """
    Always returns False

    """
    return False


def none(*args, **kwargs):
    return False


def superuser(*args, **kwargs):
    return False


def self(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Check if accessing_obj is the same as accessed_obj

    Usage:
       self()

    This can be used to lock specifically only to
    the same object that the lock is defined on.
    """
    return accessing_obj == accessed_obj


def perm(accessing_obj, accessed_obj, *args, **kwargs):
    """
    The basic permission-checker. Ignores case.

    Usage:
       perm(<permission>)

    where <permission> is the permission accessing_obj must
    have in order to pass the lock.

    If the given permission is part of settings.PERMISSION_HIERARCHY,
    permission is also granted to all ranks higher up in the hierarchy.

    If accessing_object is an Object controlled by an Account, the
    permissions of the Account is used unless the Attribute _quell
    is set to True on the Object. In this case however, the
    LOWEST hieararcy-permission of the Account/Object-pair will be used
    (this is order to avoid Accounts potentially escalating their own permissions
    by use of a higher-level Object)

    For non-hierarchical permissions, a puppeted object's account is checked first,
    followed by the puppet (unless quelled, when only puppet's access is checked).

    """
    # this allows the perm_above lockfunc to make use of this function too
    try:
        permission = args[0].lower()
        perms_object = accessing_obj.permissions.all()
    except (AttributeError, IndexError):
        return False

    gtmode = kwargs.pop("_greater_than", False)
    is_quell = False

    account = (
        utils.inherits_from(accessing_obj, "evennia.objects.objects.DefaultObject")
        and accessing_obj.account
    )
    # check object perms (note that accessing_obj could be an Account too)
    perms_account = []
    if account:
        perms_account = account.permissions.all()
        is_quell = account.attributes.get("_quell")

    # Check hirarchy matches; handle both singular/plural forms in hierarchy
    hpos_target = None
    if permission in _PERMISSION_HIERARCHY:
        hpos_target = _PERMISSION_HIERARCHY.index(permission)
    if permission.endswith("s") and permission[:-1] in _PERMISSION_HIERARCHY:
        hpos_target = _PERMISSION_HIERARCHY.index(permission[:-1])
    if hpos_target is not None:
        # hieratchy match
        hpos_account = -1
        hpos_object = -1

        if account:
            # we have an account puppeting this object. We must check what perms it has
            perms_account_single = [p[:-1] if p.endswith("s") else p for p in perms_account]
            hpos_account = [
                hpos
                for hpos, hperm in enumerate(_PERMISSION_HIERARCHY)
                if hperm in perms_account_single
            ]
            hpos_account = hpos_account and hpos_account[-1] or -1

        if not account or is_quell:
            # only get the object-level perms if there is no account or quelling
            perms_object_single = [p[:-1] if p.endswith("s") else p for p in perms_object]
            hpos_object = [
                hpos
                for hpos, hperm in enumerate(_PERMISSION_HIERARCHY)
                if hperm in perms_object_single
            ]
            hpos_object = hpos_object and hpos_object[-1] or -1

        if account and is_quell:
            # quell mode: use smallest perm from account and object
            if gtmode:
                return hpos_target < min(hpos_account, hpos_object)
            else:
                return hpos_target <= min(hpos_account, hpos_object)
        elif account:
            # use account perm
            if gtmode:
                return hpos_target < hpos_account
            else:
                return hpos_target <= hpos_account
        else:
            # use object perm
            if gtmode:
                return hpos_target < hpos_object
            else:
                return hpos_target <= hpos_object
    else:
        # no hierarchy match - check direct matches
        if account:
            # account exists
            if is_quell and permission in perms_object:
                # if quelled, first check object
                return True
            elif permission in perms_account:
                # unquelled - check account
                return True
            else:
                # no account-pass, check object pass
                return permission in perms_object

        elif permission in perms_object:
            return True

    return False


def perm_above(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Only allow objects with a permission *higher* in the permission
    hierarchy than the one given. If there is no such higher rank,
    it's assumed we refer to superuser. If no hierarchy is defined,
    this function has no meaning and returns False.
    """
    kwargs["_greater_than"] = True
    return perm(accessing_obj, accessed_obj, *args, **kwargs)


def pperm(accessing_obj, accessed_obj, *args, **kwargs):
    """
    The basic permission-checker only for Account objects. Ignores case.

    Usage:
       pperm(<permission>)

    where <permission> is the permission accessing_obj must
    have in order to pass the lock. If the given permission
    is part of _PERMISSION_HIERARCHY, permission is also granted
    to all ranks higher up in the hierarchy.
    """
    return perm(_to_account(accessing_obj), accessed_obj, *args, **kwargs)


def pperm_above(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Only allow Account objects with a permission *higher* in the permission
    hierarchy than the one given. If there is no such higher rank,
    it's assumed we refer to superuser. If no hierarchy is defined,
    this function has no meaning and returns False.
    """
    return perm_above(_to_account(accessing_obj), accessed_obj, *args, **kwargs)


def dbref(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
      dbref(3)

    This lock type checks if the checking object
    has a particular dbref. Note that this only
    works for checking objects that are stored
    in the database (e.g. not for commands)
    """
    if not args:
        return False
    try:
        dbr = int(args[0].strip().strip("#"))
    except ValueError:
        return False
    if hasattr(accessing_obj, "dbid"):
        return dbr == accessing_obj.dbid
    return False


def pdbref(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Same as dbref, but making sure accessing_obj is an account.
    """
    return dbref(_to_account(accessing_obj), accessed_obj, *args, **kwargs)


def id(accessing_obj, accessed_obj, *args, **kwargs):
    "Alias to dbref"
    return dbref(accessing_obj, accessed_obj, *args, **kwargs)


def pid(accessing_obj, accessed_obj, *args, **kwargs):
    "Alias to dbref, for Accounts"
    return dbref(_to_account(accessing_obj), accessed_obj, *args, **kwargs)


# this is more efficient than multiple if ... elif statments
CF_MAPPING = {
    "eq": lambda val1, val2: val1 == val2 or str(val1) == str(val2) or float(val1) == float(val2),
    "gt": lambda val1, val2: float(val1) > float(val2),
    "lt": lambda val1, val2: float(val1) < float(val2),
    "ge": lambda val1, val2: float(val1) >= float(val2),
    "le": lambda val1, val2: float(val1) <= float(val2),
    "ne": lambda val1, val2: float(val1) != float(val2),
    "default": lambda val1, val2: False,
}


def attr(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
      attr(attrname)
      attr(attrname, value)
      attr(attrname, value, compare=type)

    where compare's type is one of (eq,gt,lt,ge,le,ne) and signifies
    how the value should be compared with one on accessing_obj (so
    compare=gt means the accessing_obj must have a value greater than
    the one given).

    Searches attributes *and* properties stored on the accessing_obj.
    if accessing_obj has a property "obj", then this is used as
    accessing_obj (this makes this usable for Commands too)

    The first form works like a flag - if the attribute/property
    exists on the object, the value is checked for True/False. The
    second form also requires that the value of the attribute/property
    matches. Note that all retrieved values will be converted to
    strings before doing the comparison.
    """
    # deal with arguments
    if not args:
        return False
    attrname = args[0].strip()
    value = None
    if len(args) > 1:
        value = args[1].strip()
    compare = "eq"
    if kwargs:
        compare = kwargs.get("compare", "eq")

    def valcompare(val1, val2, typ="eq"):
        "compare based on type"
        try:
            return CF_MAPPING.get(typ, CF_MAPPING["default"])(val1, val2)
        except Exception:
            # this might happen if we try to compare two things that
            # cannot be compared
            return False

    if hasattr(accessing_obj, "obj"):
        # NOTE: this is relevant for Commands. It may clash with scripts
        # (they have Attributes and .obj) , but are scripts really
        # used so that one ever wants to check the property on the
        # Script rather than on its owner?
        accessing_obj = accessing_obj.obj

    # first, look for normal properties on the object trying to gain access
    if hasattr(accessing_obj, attrname):
        if value:
            return valcompare(str(getattr(accessing_obj, attrname)), value, compare)
        # will return Fail on False value etc
        return bool(getattr(accessing_obj, attrname))
    # check attributes, if they exist
    if hasattr(accessing_obj, "attributes") and accessing_obj.attributes.has(attrname):
        if value:
            return hasattr(accessing_obj, "attributes") and valcompare(
                accessing_obj.attributes.get(attrname), value, compare
            )
        # fails on False/None values
        return bool(accessing_obj.attributes.get(attrname))
    return False


def objattr(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
      objattr(attrname)
      objattr(attrname, value)
      objattr(attrname, value, compare=type)

    Works like attr, except it looks for an attribute on
    accessed_obj instead.

    """
    return attr(accessed_obj, accessed_obj, *args, **kwargs)


def locattr(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
      locattr(attrname)
      locattr(attrname, value)
      locattr(attrname, value, compare=type)

    Works like attr, except it looks for an attribute on
    accessing_obj.location, if such an entity exists.

    if accessing_obj has a property ".obj" (such as is the case for a
    Command), then accessing_obj.obj.location is used instead.

    """
    if hasattr(accessing_obj, "obj"):
        accessing_obj = accessing_obj.obj
    if hasattr(accessing_obj, "location"):
        return attr(accessing_obj.location, accessed_obj, *args, **kwargs)
    return False


def objlocattr(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
      locattr(attrname)
      locattr(attrname, value)
      locattr(attrname, value, compare=type)

    Works like attr, except it looks for an attribute on
    accessed_obj.location, if such an entity exists.

    if accessed_obj has a property ".obj" (such as is the case for a
    Command), then accessing_obj.obj.location is used instead.

    """
    if hasattr(accessed_obj, "obj"):
        accessed_obj = accessed_obj.obj
    if hasattr(accessed_obj, "location"):
        return attr(accessed_obj.location, accessed_obj, *args, **kwargs)
    return False


def attr_eq(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
       attr_gt(attrname, 54)
    """
    return attr(accessing_obj, accessed_obj, *args, **kwargs)


def attr_gt(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
       attr_gt(attrname, 54)

    Only true if access_obj's attribute > the value given.
    """
    return attr(accessing_obj, accessed_obj, *args, **{"compare": "gt"})


def attr_ge(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
       attr_gt(attrname, 54)

    Only true if access_obj's attribute >= the value given.
    """
    return attr(accessing_obj, accessed_obj, *args, **{"compare": "ge"})


def attr_lt(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
       attr_gt(attrname, 54)

    Only true if access_obj's attribute < the value given.
    """
    return attr(accessing_obj, accessed_obj, *args, **{"compare": "lt"})


def attr_le(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
       attr_gt(attrname, 54)

    Only true if access_obj's attribute <= the value given.
    """
    return attr(accessing_obj, accessed_obj, *args, **{"compare": "le"})


def attr_ne(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
       attr_gt(attrname, 54)

    Only true if access_obj's attribute != the value given.
    """
    return attr(accessing_obj, accessed_obj, *args, **{"compare": "ne"})


def tag(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
        tag(tagkey)
        tag(tagkey, category)

    Only true if accessing_obj has the specified tag and optional
    category.
    If accessing_obj has the ".obj" property (such as is the case for
    a command), then accessing_obj.obj is used instead.

    """
    if hasattr(accessing_obj, "obj"):
        accessing_obj = accessing_obj.obj
    tagkey = args[0] if args else None
    category = args[1] if len(args) > 1 else None
    return bool(accessing_obj.tags.get(tagkey, category=category))


def objtag(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
        objtag(tagkey)
        objtag(tagkey, category):

    Only true if `accessed_obj` has the given tag and optional category.

    """
    return tag(accessed_obj, None, *args, **kwargs)


def objloctag(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
        objloctag(tagkey)
        objloctag(tagkey, category):

    Only true if `accessed_obj.location` has the given tag and optional category.
    If obj has no location, this lockfunc fails.

    """
    try:
        return tag(accessed_obj.location, None, *args, **kwargs)
    except AttributeError:
        return False


def is_ooc(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
        is_ooc()

    This is normally used to lock a Command, so it can be used
    only when out of character. When not logged in at all, this
    function will still return True.
    """
    obj = accessed_obj.obj if hasattr(accessed_obj, "obj") else accessed_obj
    account = obj.account if hasattr(obj, "account") else obj
    if not account:
        return True
    try:
        session = accessed_obj.session
    except AttributeError:
        # note-this doesn't work well
        # for high multisession mode. We may need
        # to change to sessiondb to resolve this
        sessions = session = account.sessions.get()
        session = sessions[0] if sessions else None
    if not session:
        # this suggests we are not even logged in; treat as ooc.
        return True
    try:
        return not account.get_puppet(session)
    except TypeError:
        return not session.get_puppet()


def objtag(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
        objtag(tagkey)
        objtag(tagkey, category)

    Only true if accessed_obj has the specified tag and optional
    category.
    """
    tagkey = args[0] if args else None
    category = args[1] if len(args) > 1 else None
    return bool(accessed_obj.tags.get(tagkey, category=category))


def inside(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
       inside()

    True if accessing_obj is 'inside' accessing_obj. Note that this only checks
    one level down. So if if the lock is on a room, you will pass but not your
    inventory (since their location is you, not the locked object).  If you
    want also nested objects to pass the lock, use the `insiderecursive`
    lockfunc.
    """
    if hasattr(accessed_obj, "obj"):
        accessed_obj = accessed_obj.obj
    return accessing_obj.location == accessed_obj


def inside_rec(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
        inside_rec()

    True if accessing_obj is inside the accessed obj, at up to 10 levels
    of recursion (so if this lock is on a room, then an object inside a box
    in your inventory will also pass the lock).
    """

    def _recursive_inside(obj, accessed_obj, lvl=1):
        if obj.location:
            if obj.location == accessed_obj:
                return True
            elif lvl >= 10:
                # avoid infinite recursions
                return False
            else:
                return _recursive_inside(obj.location, accessed_obj, lvl + 1)
        return False

    return _recursive_inside(accessing_obj, accessed_obj)


def holds(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Usage:
      holds()            checks if accessed_obj or accessed_obj.obj
                         is held by accessing_obj
      holds(key/dbref)   checks if accessing_obj holds an object
                          with given key/dbref
      holds(attrname, value)   checks if accessing_obj holds an
                               object with the given attrname and value

    This is passed if accessed_obj is carried by accessing_obj (that is,
    accessed_obj.location == accessing_obj), or if accessing_obj itself holds
    an object matching the given key.
    """
    try:
        # commands and scripts don't have contents, so we are usually looking
        # for the contents of their .obj property instead (i.e. the object the
        # command/script is attached to).
        contents = accessing_obj.contents
    except AttributeError:
        try:
            contents = accessing_obj.obj.contents
        except AttributeError:
            return False

    def check_holds(objid):
        # helper function. Compares both dbrefs and keys/aliases.
        objid = str(objid)
        dbref = utils.dbref(objid, reqhash=False)
        if dbref and any((True for obj in contents if obj.dbid == dbref)):
            return True
        objid = objid.lower()
        return any(
            (
                True
                for obj in contents
                if obj.key.lower() == objid or objid in [al.lower() for al in obj.aliases.all()]
            )
        )

    if not args:
        # holds() - check if accessed_obj or accessed_obj.obj is held by accessing_obj
        try:
            if check_holds(accessed_obj.dbid):
                return True
        except Exception:
            # we need to catch any trouble here
            pass
        return hasattr(accessed_obj, "obj") and check_holds(accessed_obj.obj.dbid)
    if len(args) == 1:
        # command is holds(dbref/key) - check if given objname/dbref is held by accessing_ob
        return check_holds(args[0])
    elif len(args) > 1:
        # command is holds(attrname, value) check if any held object has the given attribute and value
        for obj in contents:
            if obj.attributes.get(args[0]) == args[1]:
                return True
    return False


def has_account(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Only returns true if accessing_obj has_account is true, that is,
    this is an account-controlled object. It fails on actual accounts!

    This is a useful lock for traverse-locking Exits to restrain NPC
    mobiles from moving outside their areas.
    """
    return hasattr(accessing_obj, "has_account") and accessing_obj.has_account


def serversetting(accessing_obj, accessed_obj, *args, **kwargs):
    """
    Only returns true if the Evennia settings exists, alternatively has
    a certain value.

    Usage:
      serversetting(IRC_ENABLED)
      serversetting(BASE_SCRIPT_PATH, ['types'])

    A given True/False or integers will be converted properly. Note that
    everything will enter this function as strings, so they have to be
    unpacked to their real value. We only support basic properties.
    """
    if not args or not args[0]:
        return False
    if len(args) < 2:
        setting = args[0]
        val = "True"
    else:
        setting, val = args[0], args[1]
    # convert
    try:
        val = literal_eval(val)
    except Exception:
        # we swallow errors here, lockfuncs has noone to report to
        return False

    if setting in settings._wrapped.__dict__:
        return settings._wrapped.__dict__[setting] == val
    return False