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ChannelStats: Use the safe math evaluator.

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This commit is contained in:
Valentin Lorentz 2020-01-26 20:42:38 +01:00
parent 99dd6f1506
commit a6ae9f51a3
2 changed files with 18 additions and 23 deletions
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28
plugins/ChannelStats/plugin.py
View File

@ -44,6 +44,7 @@ import supybot.ircmsgs as ircmsgs
import supybot.plugins as plugins
import supybot.ircutils as ircutils
import supybot.callbacks as callbacks
from supybot.utils.math_evaluator import safe_eval, InvalidNode
_ = PluginInternationalization('ChannelStats')
@ -292,15 +293,6 @@ class ChannelStats(callbacks.Plugin):
name, channel))
stats = wrap(stats, ['channeldb', additional('something')])
_calc_match_forbidden_chars = re.compile('[_\[\]]')
_env = {'__builtins__': types.ModuleType('__builtins__')}
_env.update(math.__dict__)
def _factorial(x):
if x<=10000:
return math.factorial(x)
else:
raise Exception('factorial argument too large')
_env['factorial'] = _factorial
@internationalizeDocstring
def rank(self, irc, msg, args, channel, expr):
"""[<channel>] <stat expression>
@ -314,30 +306,26 @@ class ChannelStats(callbacks.Plugin):
if msg.nick not in irc.state.channels[channel].users:
irc.error(format('You must be in %s to use this command.', channel))
return
# XXX I could do this the right way, and abstract out a safe eval,
# or I could just copy/paste from the Math plugin.
if self._calc_match_forbidden_chars.match(expr):
irc.error(_('There\'s really no reason why you should have '
'underscores or brackets in your mathematical '
'expression. Please remove them.'), Raise=True)
if 'lambda' in expr:
irc.error(_('You can\'t use lambda in this command.'), Raise=True)
expr = expr.lower()
users = []
for ((c, id), stats) in self.db.items():
if ircutils.strEqual(c, channel) and \
(id == 0 or ircdb.users.hasUser(id)):
e = self._env.copy()
e = {}
for attr in stats._values:
e[attr] = float(getattr(stats, attr))
try:
v = eval(expr, e, e)
v = safe_eval(expr, allow_ints=True, variables=e)
except ZeroDivisionError:
v = float('inf')
except NameError as e:
irc.errorInvalid(_('stat variable'), str(e).split()[1])
irc.errorInvalid(_('stat variable'), str(e))
except InvalidNode as e:
irc.error(_('Invalid syntax: %s') % e.args[0], Raise=True)
except Exception as e:
irc.error(utils.exnToString(e), Raise=True)
else:
v = float(v)
if id == 0:
users.append((v, irc.nick))
else:

13
src/utils/math_evaluator.py
View File

@ -27,6 +27,10 @@
# POSSIBILITY OF SUCH DAMAGE.
###
"""A safe evaluator for math expressions using Python syntax.
Unlike eval(), it can be run on untrusted input.
"""
import ast
import math
import cmath
@ -122,9 +126,12 @@ UNSAFE_ENV.update(filter_module(math, 'ceil floor factorial gcd'.split()))
# It would be nice if ast.literal_eval used a visitor so we could subclass
# to extend it, but it doesn't, so let's reimplement it entirely.
class SafeEvalVisitor(ast.NodeVisitor):
def __init__(self, allow_ints):
def __init__(self, allow_ints, variables=None):
self._allow_ints = allow_ints
self._env = UNSAFE_ENV if allow_ints else SAFE_ENV
if variables:
self._env = self._env.copy()
self._env.update(variables)
def _convert_num(self, x):
"""Converts numbers to complex if ints are not allowed."""
@ -178,6 +185,6 @@ class SafeEvalVisitor(ast.NodeVisitor):
def generic_visit(self, node):
raise InvalidNode('illegal construct %s' % node.__class__.__name__)
def safe_eval(text, allow_ints):
def safe_eval(text, allow_ints, variables=None):
node = ast.parse(text, mode='eval')
return SafeEvalVisitor(allow_ints).visit(node)
return SafeEvalVisitor(allow_ints, variables=variables).visit(node)