"""
commands.requires
=================
This module manages the logic of resolving command permissions and
requirements. This includes rules which override those requirements,
as well as custom checks which can be overriden, and some special
checks like bot permissions checks.
"""
import asyncio
import enum
import inspect
from collections import ChainMap
from typing import (
Union,
Optional,
List,
Callable,
Awaitable,
Dict,
Any,
TYPE_CHECKING,
TypeVar,
Tuple,
ClassVar,
Mapping,
)
import discord
from .converter import GuildConverter
from .errors import BotMissingPermissions
if TYPE_CHECKING:
from .commands import Command
from .context import Context
_CommandOrCoro = TypeVar("_CommandOrCoro", Callable[..., Awaitable[Any]], Command)
__all__ = [
"CheckPredicate",
"DM_PERMS",
"GlobalPermissionModel",
"GuildPermissionModel",
"PermissionModel",
"PrivilegeLevel",
"PermState",
"Requires",
"permissions_check",
"bot_has_permissions",
"has_permissions",
"has_guild_permissions",
"is_owner",
"guildowner",
"guildowner_or_permissions",
"admin",
"admin_or_permissions",
"mod",
"mod_or_permissions",
"transition_permstate_to",
"PermStateTransitions",
"PermStateAllowedStates",
]
_T = TypeVar("_T")
GlobalPermissionModel = Union[
discord.User,
discord.VoiceChannel,
discord.TextChannel,
discord.CategoryChannel,
discord.Role,
GuildConverter, # Unfortunately this will have to do for now
]
GuildPermissionModel = Union[
discord.Member,
discord.VoiceChannel,
discord.TextChannel,
discord.CategoryChannel,
discord.Role,
GuildConverter,
]
PermissionModel = Union[GlobalPermissionModel, GuildPermissionModel]
CheckPredicate = Callable[["Context"], Union[Optional[bool], Awaitable[Optional[bool]]]]
# Here we are trying to model DM permissions as closely as possible. The only
# discrepancy I've found is that users can pin messages, but they cannot delete them.
# This means manage_messages is only half True, so it's left as False.
# This is also the same as the permissions returned when `permissions_for` is used in DM.
DM_PERMS = discord.Permissions.none()
DM_PERMS.update(
add_reactions=True,
attach_files=True,
embed_links=True,
external_emojis=True,
mention_everyone=True,
read_message_history=True,
read_messages=True,
send_messages=True,
)
[docs]class PrivilegeLevel(enum.IntEnum):
"""Enumeration for special privileges."""
# Maintainer Note: do NOT re-order these.
# Each privilege level also implies access to the ones before it.
# Inserting new privilege levels at a later point is fine if that is considered.
NONE = enum.auto()
"""No special privilege level."""
MOD = enum.auto()
"""User has the mod role."""
ADMIN = enum.auto()
"""User has the admin role."""
GUILD_OWNER = enum.auto()
"""User is the guild level."""
BOT_OWNER = enum.auto()
"""User is a bot owner."""
@classmethod
async def from_ctx(cls, ctx: "Context") -> "PrivilegeLevel":
"""Get a command author's PrivilegeLevel based on context."""
if await ctx.bot.is_owner(ctx.author):
return cls.BOT_OWNER
elif ctx.guild is None:
return cls.NONE
elif ctx.author == ctx.guild.owner:
return cls.GUILD_OWNER
# The following is simply an optimised way to check if the user has the
# admin or mod role.
guild_settings = ctx.bot._config.guild(ctx.guild)
member_snowflakes = ctx.author._roles # DEP-WARN
for snowflake in await guild_settings.admin_role():
if member_snowflakes.has(snowflake): # DEP-WARN
return cls.ADMIN
for snowflake in await guild_settings.mod_role():
if member_snowflakes.has(snowflake): # DEP-WARN
return cls.MOD
return cls.NONE
def __repr__(self) -> str:
return f"<{self.__class__.__name__}.{self.name}>"
[docs]class PermState(enum.Enum):
"""Enumeration for permission states used by rules."""
ACTIVE_ALLOW = enum.auto()
"""This command has been actively allowed, default user checks
should be ignored.
"""
NORMAL = enum.auto()
"""No overrides have been set for this command, make determination
from default user checks.
"""
PASSIVE_ALLOW = enum.auto()
"""There exists a subcommand in the `ACTIVE_ALLOW` state, continue
down the subcommand tree until we either find it or realise we're
on the wrong branch.
"""
CAUTIOUS_ALLOW = enum.auto()
"""This command has been actively denied, but there exists a
subcommand in the `ACTIVE_ALLOW` state. This occurs when
`PASSIVE_ALLOW` and `ACTIVE_DENY` are combined.
"""
ACTIVE_DENY = enum.auto()
"""This command has been actively denied, terminate the command
chain.
"""
# The below are valid states, but should not be transitioned to
# They should be set if they apply.
ALLOWED_BY_HOOK = enum.auto()
"""This command has been actively allowed by a permission hook.
check validation doesn't need this, but is useful to developers"""
DENIED_BY_HOOK = enum.auto()
"""This command has been actively denied by a permission hook
check validation doesn't need this, but is useful to developers"""
@classmethod
def from_bool(cls, value: Optional[bool]) -> "PermState":
"""Get a PermState from a bool or ``NoneType``."""
if value is True:
return cls.ACTIVE_ALLOW
elif value is False:
return cls.ACTIVE_DENY
else:
return cls.NORMAL
def __repr__(self) -> str:
return f"<{self.__class__.__name__}.{self.name}>"
# Here we're defining how we transition between states.
# The dict is in the form:
# previous state -> this state -> Tuple[override, next state]
# "override" is a bool describing whether or not the command should be
# invoked. It can be None, in which case the default permission checks
# will be used instead.
# There is also one case where the "next state" is dependent on the
# result of the default permission checks - the transition from NORMAL
# to PASSIVE_ALLOW. In this case "next state" is a dict mapping the
# permission check results to the actual next state.
TransitionResult = Tuple[Optional[bool], Union[PermState, Dict[bool, PermState]]]
TransitionDict = Dict[PermState, Dict[PermState, TransitionResult]]
PermStateTransitions: TransitionDict = {
PermState.ACTIVE_ALLOW: {
PermState.ACTIVE_ALLOW: (True, PermState.ACTIVE_ALLOW),
PermState.NORMAL: (True, PermState.ACTIVE_ALLOW),
PermState.PASSIVE_ALLOW: (True, PermState.ACTIVE_ALLOW),
PermState.CAUTIOUS_ALLOW: (True, PermState.CAUTIOUS_ALLOW),
PermState.ACTIVE_DENY: (False, PermState.ACTIVE_DENY),
},
PermState.NORMAL: {
PermState.ACTIVE_ALLOW: (True, PermState.ACTIVE_ALLOW),
PermState.NORMAL: (None, PermState.NORMAL),
PermState.PASSIVE_ALLOW: (True, {True: PermState.NORMAL, False: PermState.PASSIVE_ALLOW}),
PermState.CAUTIOUS_ALLOW: (True, PermState.CAUTIOUS_ALLOW),
PermState.ACTIVE_DENY: (False, PermState.ACTIVE_DENY),
},
PermState.PASSIVE_ALLOW: {
PermState.ACTIVE_ALLOW: (True, PermState.ACTIVE_ALLOW),
PermState.NORMAL: (False, PermState.NORMAL),
PermState.PASSIVE_ALLOW: (True, PermState.PASSIVE_ALLOW),
PermState.CAUTIOUS_ALLOW: (True, PermState.CAUTIOUS_ALLOW),
PermState.ACTIVE_DENY: (False, PermState.ACTIVE_DENY),
},
PermState.CAUTIOUS_ALLOW: {
PermState.ACTIVE_ALLOW: (True, PermState.ACTIVE_ALLOW),
PermState.NORMAL: (False, PermState.ACTIVE_DENY),
PermState.PASSIVE_ALLOW: (True, PermState.CAUTIOUS_ALLOW),
PermState.CAUTIOUS_ALLOW: (True, PermState.CAUTIOUS_ALLOW),
PermState.ACTIVE_DENY: (False, PermState.ACTIVE_DENY),
},
PermState.ACTIVE_DENY: { # We can only start from ACTIVE_DENY if it is set on a cog.
PermState.ACTIVE_ALLOW: (True, PermState.ACTIVE_ALLOW), # Should never happen
PermState.NORMAL: (False, PermState.ACTIVE_DENY),
PermState.PASSIVE_ALLOW: (False, PermState.ACTIVE_DENY), # Should never happen
PermState.CAUTIOUS_ALLOW: (False, PermState.ACTIVE_DENY), # Should never happen
PermState.ACTIVE_DENY: (False, PermState.ACTIVE_DENY),
},
}
PermStateAllowedStates = (
PermState.ACTIVE_ALLOW,
PermState.PASSIVE_ALLOW,
PermState.CAUTIOUS_ALLOW,
)
def transition_permstate_to(prev: PermState, next_state: PermState) -> TransitionResult:
return PermStateTransitions[prev][next_state]
[docs]class Requires:
"""This class describes the requirements for executing a specific command.
The permissions described include both bot permissions and user
permissions.
Attributes
----------
checks : List[Callable[[Context], Union[bool, Awaitable[bool]]]]
A list of checks which can be overridden by rules. Use
`Command.checks` if you would like them to never be overridden.
privilege_level : PrivilegeLevel
The required privilege level (bot owner, admin, etc.) for users
to execute the command. Can be ``None``, in which case the
`user_perms` will be used exclusively, otherwise, for levels
other than bot owner, the user can still run the command if
they have the required `user_perms`.
ready_event : asyncio.Event
Event for when this Requires object has had its rules loaded.
If permissions is loaded, this should be set when permissions
has finished loading rules into this object. If permissions
is not loaded, it should be set as soon as the command or cog
is added.
user_perms : Optional[discord.Permissions]
The required permissions for users to execute the command. Can
be ``None``, in which case the `privilege_level` will be used
exclusively, otherwise, it will pass whether the user has the
required `privilege_level` _or_ `user_perms`.
bot_perms : discord.Permissions
The required bot permissions for a command to be executed. This
is not overrideable by other conditions.
"""
DEFAULT: ClassVar[str] = "default"
"""The key for the default rule in a rules dict."""
GLOBAL: ClassVar[int] = 0
"""Should be used in place of a guild ID when setting/getting
global rules.
"""
def __init__(
self,
privilege_level: Optional[PrivilegeLevel],
user_perms: Union[Dict[str, bool], discord.Permissions, None],
bot_perms: Union[Dict[str, bool], discord.Permissions],
checks: List[CheckPredicate],
):
self.checks: List[CheckPredicate] = checks
self.privilege_level: Optional[PrivilegeLevel] = privilege_level
self.ready_event = asyncio.Event()
if isinstance(user_perms, dict):
self.user_perms: Optional[discord.Permissions] = discord.Permissions.none()
_validate_perms_dict(user_perms)
self.user_perms.update(**user_perms)
else:
self.user_perms = user_perms
if isinstance(bot_perms, dict):
self.bot_perms: discord.Permissions = discord.Permissions.none()
_validate_perms_dict(bot_perms)
self.bot_perms.update(**bot_perms)
else:
self.bot_perms = bot_perms
self._global_rules: _RulesDict = _RulesDict()
self._guild_rules: _IntKeyDict[_RulesDict] = _IntKeyDict[_RulesDict]()
@staticmethod
def get_decorator(
privilege_level: Optional[PrivilegeLevel], user_perms: Optional[Dict[str, bool]]
) -> Callable[["_CommandOrCoro"], "_CommandOrCoro"]:
if not user_perms:
user_perms = None
def decorator(func: "_CommandOrCoro") -> "_CommandOrCoro":
if inspect.iscoroutinefunction(func):
func.__requires_privilege_level__ = privilege_level
func.__requires_user_perms__ = user_perms
else:
func.requires.privilege_level = privilege_level
if user_perms is None:
func.requires.user_perms = None
else:
_validate_perms_dict(user_perms)
assert func.requires.user_perms is not None
func.requires.user_perms.update(**user_perms)
return func
return decorator
[docs] def get_rule(self, model: Union[int, str, PermissionModel], guild_id: int) -> PermState:
"""Get the rule for a particular model.
Parameters
----------
model : Union[int, str, PermissionModel]
The model to get the rule for. `str` is only valid for
`Requires.DEFAULT`.
guild_id : int
The ID of the guild for the rule's scope. Set to
`Requires.GLOBAL` for a global rule.
If a global rule is set for a model,
it will be prefered over the guild rule.
Returns
-------
PermState
The state for this rule. See the `PermState` class
for an explanation.
"""
if not isinstance(model, (str, int)):
model = model.id
rules: Mapping[Union[int, str], PermState]
if guild_id:
rules = ChainMap(self._global_rules, self._guild_rules.get(guild_id, _RulesDict()))
else:
rules = self._global_rules
return rules.get(model, PermState.NORMAL)
[docs] def set_rule(self, model_id: Union[str, int], rule: PermState, guild_id: int) -> None:
"""Set the rule for a particular model.
Parameters
----------
model_id : Union[str, int]
The model to add a rule for. `str` is only valid for
`Requires.DEFAULT`.
rule : PermState
Which state this rule should be set as. See the `PermState`
class for an explanation.
guild_id : int
The ID of the guild for the rule's scope. Set to
`Requires.GLOBAL` for a global rule.
"""
if guild_id:
rules = self._guild_rules.setdefault(guild_id, _RulesDict())
else:
rules = self._global_rules
if rule is PermState.NORMAL:
rules.pop(model_id, None)
else:
rules[model_id] = rule
[docs] def clear_all_rules(self, guild_id: int, *, preserve_default_rule: bool = True) -> None:
"""Clear all rules of a particular scope.
Parameters
----------
guild_id : int
The guild ID to clear rules for. If set to
`Requires.GLOBAL`, this will clear all global rules and
leave all guild rules untouched.
Other Parameters
----------------
preserve_default_rule : bool
Whether to preserve the default rule or not.
This defaults to being preserved
"""
if guild_id:
rules = self._guild_rules.setdefault(guild_id, _RulesDict())
else:
rules = self._global_rules
default = rules.get(self.DEFAULT, None)
rules.clear()
if default is not None and preserve_default_rule:
rules[self.DEFAULT] = default
[docs] def reset(self) -> None:
"""Reset this Requires object to its original state.
This will clear all rules, including defaults. It also resets
the `Requires.ready_event`.
"""
self._guild_rules.clear() # pylint: disable=no-member
self._global_rules.clear() # pylint: disable=no-member
self.ready_event.clear()
[docs] async def verify(self, ctx: "Context") -> bool:
"""Check if the given context passes the requirements.
This will check the bot permissions, overrides, user permissions
and privilege level.
Parameters
----------
ctx : "Context"
The invkokation context to check with.
Returns
-------
bool
``True`` if the context passes the requirements.
Raises
------
BotMissingPermissions
If the bot is missing required permissions to run the
command.
CommandError
Propogated from any permissions checks.
"""
if not self.ready_event.is_set():
await self.ready_event.wait()
await self._verify_bot(ctx)
# Owner should never be locked out of commands for user permissions.
if await ctx.bot.is_owner(ctx.author):
return True
# Owner-only commands are non-overrideable, and we already checked for owner.
if self.privilege_level is PrivilegeLevel.BOT_OWNER:
return False
hook_result = await ctx.bot.verify_permissions_hooks(ctx)
if hook_result is not None:
return hook_result
return await self._transition_state(ctx)
async def _verify_bot(self, ctx: "Context") -> None:
if ctx.guild is None:
bot_user = ctx.bot.user
else:
bot_user = ctx.guild.me
bot_perms = ctx.channel.permissions_for(bot_user)
if not (bot_perms.administrator or bot_perms >= self.bot_perms):
raise BotMissingPermissions(missing=self._missing_perms(self.bot_perms, bot_perms))
async def _transition_state(self, ctx: "Context") -> bool:
prev_state = ctx.permission_state
cur_state = self._get_rule_from_ctx(ctx)
should_invoke, next_state = transition_permstate_to(prev_state, cur_state)
if should_invoke is None:
# NORMAL invokation, we simply follow standard procedure
should_invoke = await self._verify_user(ctx)
elif isinstance(next_state, dict):
# NORMAL to PASSIVE_ALLOW; should we proceed as normal or transition?
# We must check what would happen normally, if no explicit rules were set.
default_rule = PermState.NORMAL
if ctx.guild is not None:
default_rule = self.get_rule(self.DEFAULT, guild_id=ctx.guild.id)
if default_rule is PermState.NORMAL:
default_rule = self.get_rule(self.DEFAULT, self.GLOBAL)
if default_rule == PermState.ACTIVE_DENY:
would_invoke = False
elif default_rule == PermState.ACTIVE_ALLOW:
would_invoke = True
else:
would_invoke = await self._verify_user(ctx)
next_state = next_state[would_invoke]
assert isinstance(next_state, PermState)
ctx.permission_state = next_state
return should_invoke
async def _verify_user(self, ctx: "Context") -> bool:
checks_pass = await self._verify_checks(ctx)
if checks_pass is False:
return False
if self.user_perms is not None:
user_perms = ctx.channel.permissions_for(ctx.author)
if user_perms.administrator or user_perms >= self.user_perms:
return True
if self.privilege_level is not None:
privilege_level = await PrivilegeLevel.from_ctx(ctx)
if privilege_level >= self.privilege_level:
return True
return False
def _get_rule_from_ctx(self, ctx: "Context") -> PermState:
author = ctx.author
guild = ctx.guild
if ctx.guild is None:
# We only check the user for DM channels
rule = self._global_rules.get(author.id)
if rule is not None:
return rule
return self.get_rule(self.DEFAULT, self.GLOBAL)
rules_chain = [self._global_rules]
guild_rules = self._guild_rules.get(ctx.guild.id)
if guild_rules:
rules_chain.append(guild_rules)
channels = []
if author.voice is not None:
channels.append(author.voice.channel)
channels.append(ctx.channel)
category = ctx.channel.category
if category is not None:
channels.append(category)
# We want author roles sorted highest to lowest, and exclude the @everyone role
author_roles = reversed(author.roles[1:])
model_chain = [author, *channels, *author_roles, guild]
for rules in rules_chain:
for model in model_chain:
rule = rules.get(model.id)
if rule is not None:
return rule
del model_chain[-1] # We don't check for the guild in guild rules
default_rule = self.get_rule(self.DEFAULT, guild.id)
if default_rule is PermState.NORMAL:
default_rule = self.get_rule(self.DEFAULT, self.GLOBAL)
return default_rule
async def _verify_checks(self, ctx: "Context") -> bool:
if not self.checks:
return True
return await discord.utils.async_all(check(ctx) for check in self.checks)
@staticmethod
def _get_perms_for(ctx: "Context", user: discord.abc.User) -> discord.Permissions:
if ctx.guild is None:
return DM_PERMS
else:
return ctx.channel.permissions_for(user)
@classmethod
def _get_bot_perms(cls, ctx: "Context") -> discord.Permissions:
return cls._get_perms_for(ctx, ctx.guild.me if ctx.guild else ctx.bot.user)
@staticmethod
def _missing_perms(
required: discord.Permissions, actual: discord.Permissions
) -> discord.Permissions:
# Explained in set theory terms:
# Assuming R is the set of required permissions, and A is
# the set of the user's permissions, the set of missing
# permissions will be equal to R \ A, i.e. the relative
# complement/difference of A with respect to R.
relative_complement = required.value & ~actual.value
return discord.Permissions(relative_complement)
@staticmethod
def _member_as_user(member: discord.abc.User) -> discord.User:
if isinstance(member, discord.Member):
# noinspection PyProtectedMember
return member._user
return member
def __repr__(self) -> str:
return (
f"<Requires privilege_level={self.privilege_level!r} user_perms={self.user_perms!r} "
f"bot_perms={self.bot_perms!r}>"
)
# check decorators
def permissions_check(predicate: CheckPredicate):
"""An overwriteable version of `discord.ext.commands.check`.
This has the same behaviour as `discord.ext.commands.check`,
however this check can be ignored if the command is allowed
through a permissions cog.
"""
def decorator(func: "_CommandOrCoro") -> "_CommandOrCoro":
if hasattr(func, "requires"):
func.requires.checks.append(predicate)
else:
if not hasattr(func, "__requires_checks__"):
func.__requires_checks__ = []
# noinspection PyUnresolvedReferences
func.__requires_checks__.append(predicate)
return func
return decorator
def has_guild_permissions(**perms):
"""Restrict the command to users with these guild permissions.
This check can be overridden by rules.
"""
_validate_perms_dict(perms)
def predicate(ctx):
return ctx.guild and ctx.author.guild_permissions >= discord.Permissions(**perms)
return permissions_check(predicate)
[docs]def bot_has_permissions(**perms: bool):
"""Complain if the bot is missing permissions.
If the user tries to run the command, but the bot is missing the
permissions, it will send a message describing which permissions
are missing.
This check cannot be overridden by rules.
"""
def decorator(func: "_CommandOrCoro") -> "_CommandOrCoro":
if asyncio.iscoroutinefunction(func):
func.__requires_bot_perms__ = perms
else:
_validate_perms_dict(perms)
func.requires.bot_perms.update(**perms)
return func
return decorator
[docs]def has_permissions(**perms: bool):
"""Restrict the command to users with these permissions.
This check can be overridden by rules.
"""
if perms is None:
raise TypeError("Must provide at least one keyword argument to has_permissions")
return Requires.get_decorator(None, perms)
[docs]def is_owner():
"""Restrict the command to bot owners.
This check cannot be overridden by rules.
"""
return Requires.get_decorator(PrivilegeLevel.BOT_OWNER, {})
[docs]def guildowner_or_permissions(**perms: bool):
"""Restrict the command to the guild owner or users with these permissions.
This check can be overridden by rules.
"""
return Requires.get_decorator(PrivilegeLevel.GUILD_OWNER, perms)
[docs]def guildowner():
"""Restrict the command to the guild owner.
This check can be overridden by rules.
"""
return guildowner_or_permissions()
[docs]def admin_or_permissions(**perms: bool):
"""Restrict the command to users with the admin role or these permissions.
This check can be overridden by rules.
"""
return Requires.get_decorator(PrivilegeLevel.ADMIN, perms)
[docs]def admin():
"""Restrict the command to users with the admin role.
This check can be overridden by rules.
"""
return admin_or_permissions()
[docs]def mod_or_permissions(**perms: bool):
"""Restrict the command to users with the mod role or these permissions.
This check can be overridden by rules.
"""
return Requires.get_decorator(PrivilegeLevel.MOD, perms)
[docs]def mod():
"""Restrict the command to users with the mod role.
This check can be overridden by rules.
"""
return mod_or_permissions()
class _IntKeyDict(Dict[int, _T]):
"""Dict subclass which throws TypeError when a non-int key is used."""
get: Callable
setdefault: Callable
def __getitem__(self, key: Any) -> _T:
if not isinstance(key, int):
raise TypeError("Keys must be of type `int`")
return super().__getitem__(key) # pylint: disable=no-member
def __setitem__(self, key: Any, value: _T) -> None:
if not isinstance(key, int):
raise TypeError("Keys must be of type `int`")
return super().__setitem__(key, value) # pylint: disable=no-member
class _RulesDict(Dict[Union[int, str], PermState]):
"""Dict subclass which throws a TypeError when an invalid key is used."""
get: Callable
setdefault: Callable
def __getitem__(self, key: Any) -> PermState:
if key != Requires.DEFAULT and not isinstance(key, int):
raise TypeError(f'Expected "{Requires.DEFAULT}" or int key, not "{key}"')
return super().__getitem__(key) # pylint: disable=no-member
def __setitem__(self, key: Any, value: PermState) -> None:
if key != Requires.DEFAULT and not isinstance(key, int):
raise TypeError(f'Expected "{Requires.DEFAULT}" or int key, not "{key}"')
return super().__setitem__(key, value) # pylint: disable=no-member
def _validate_perms_dict(perms: Dict[str, bool]) -> None:
invalid_keys = set(perms.keys()) - set(discord.Permissions.VALID_FLAGS)
if invalid_keys:
raise TypeError(f"Invalid perm name(s): {', '.join(invalid_keys)}")
for perm, value in perms.items():
if value is not True:
# We reject any permission not specified as 'True', since this is the only value which
# makes practical sense.
raise TypeError(f"Permission {perm} may only be specified as 'True', not {value}")
