Files
zulip/zerver/lib/validator.py
Anders Kaseorg 7e9db327b3 request: Improve validator type so mypy can check it against REQ.
Old: a validator returns None on success and returns an error string
on error.

New: a validator returns the validated value on success and raises
ValidationError on error.

This allows mypy to catch mismatches between the annotated type of a
REQ parameter and the type that the validator actually validates.

Signed-off-by: Anders Kaseorg <anders@zulip.com>
2020-06-20 22:29:15 -07:00

470 lines
17 KiB
Python

'''
This module sets up a scheme for validating that arbitrary Python
objects are correctly typed. It is totally decoupled from Django,
composable, easily wrapped, and easily extended.
A validator takes two parameters--var_name and val--and raises an
error if val is not the correct type. The var_name parameter is used
to format error messages. Validators return the validated value when
there are no errors.
Example primitive validators are check_string, check_int, and check_bool.
Compound validators are created by check_list and check_dict. Note that
those functions aren't directly called for validation; instead, those
functions are called to return other functions that adhere to the validator
contract. This is similar to how Python decorators are often parameterized.
The contract for check_list and check_dict is that they get passed in other
validators to apply to their items. This allows you to build up validators
for arbitrarily complex validators. See ValidatorTestCase for example usage.
A simple example of composition is this:
check_list(check_string)('my_list', ['a', 'b', 'c'])
To extend this concept, it's simply a matter of writing your own validator
for any particular type of object.
'''
import re
from datetime import datetime
from typing import (
Any,
Callable,
Dict,
Iterable,
List,
Optional,
Set,
Tuple,
TypeVar,
Union,
cast,
overload,
)
import ujson
from django.conf import settings
from django.core.exceptions import ValidationError
from django.core.validators import URLValidator, validate_email
from django.utils.translation import ugettext as _
from zerver.lib.request import JsonableError, ResultT
from zerver.lib.types import ProfileFieldData, Validator
FuncT = Callable[..., Any]
TypeStructure = TypeVar("TypeStructure")
USING_TYPE_STRUCTURE = settings.LOG_API_EVENT_TYPES
# The type_structure system is designed to support using the validators in
# test_events.py to create documentation for our event formats.
#
# Ultimately, it should be possible to do this with mypy rather than a
# parallel system.
def set_type_structure(type_structure: TypeStructure) -> Callable[[FuncT], Any]:
def _set_type_structure(func: FuncT) -> FuncT:
if USING_TYPE_STRUCTURE:
func.type_structure = type_structure # type: ignore[attr-defined] # monkey-patching
return func
return _set_type_structure
@set_type_structure("str")
def check_string(var_name: str, val: object) -> str:
if not isinstance(val, str):
raise ValidationError(_('{var_name} is not a string').format(var_name=var_name))
return val
@set_type_structure("str")
def check_required_string(var_name: str, val: object) -> str:
s = check_string(var_name, val)
if not s.strip():
raise ValidationError(_("{item} cannot be blank.").format(item=var_name))
return s
def check_string_in(possible_values: Union[Set[str], List[str]]) -> Validator[str]:
@set_type_structure("str")
def validator(var_name: str, val: object) -> str:
s = check_string(var_name, val)
if s not in possible_values:
raise ValidationError(_("Invalid {var_name}").format(var_name=var_name))
return s
return validator
@set_type_structure("str")
def check_short_string(var_name: str, val: object) -> str:
return check_capped_string(50)(var_name, val)
def check_capped_string(max_length: int) -> Validator[str]:
@set_type_structure("str")
def validator(var_name: str, val: object) -> str:
s = check_string(var_name, val)
if len(s) > max_length:
raise ValidationError(_("{var_name} is too long (limit: {max_length} characters)").format(
var_name=var_name, max_length=max_length,
))
return s
return validator
def check_string_fixed_length(length: int) -> Validator[str]:
@set_type_structure("str")
def validator(var_name: str, val: object) -> Optional[str]:
s = check_string(var_name, val)
if len(s) != length:
raise ValidationError(_("{var_name} has incorrect length {length}; should be {target_length}").format(
var_name=var_name, target_length=length, length=len(s),
))
return s
return validator
@set_type_structure("str")
def check_long_string(var_name: str, val: object) -> str:
return check_capped_string(500)(var_name, val)
@set_type_structure("date")
def check_date(var_name: str, val: object) -> str:
if not isinstance(val, str):
raise ValidationError(_('{var_name} is not a string').format(var_name=var_name))
try:
datetime.strptime(val, '%Y-%m-%d')
except ValueError:
raise ValidationError(_('{var_name} is not a date').format(var_name=var_name))
return val
@set_type_structure("int")
def check_int(var_name: str, val: object) -> int:
if not isinstance(val, int):
raise ValidationError(_('{var_name} is not an integer').format(var_name=var_name))
return val
def check_int_in(possible_values: List[int]) -> Validator[int]:
@set_type_structure("int")
def validator(var_name: str, val: object) -> int:
n = check_int(var_name, val)
if n not in possible_values:
raise ValidationError(_("Invalid {var_name}").format(var_name=var_name))
return n
return validator
@set_type_structure("float")
def check_float(var_name: str, val: object) -> float:
if not isinstance(val, float):
raise ValidationError(_('{var_name} is not a float').format(var_name=var_name))
return val
@set_type_structure("bool")
def check_bool(var_name: str, val: object) -> bool:
if not isinstance(val, bool):
raise ValidationError(_('{var_name} is not a boolean').format(var_name=var_name))
return val
@set_type_structure("str")
def check_color(var_name: str, val: object) -> str:
s = check_string(var_name, val)
valid_color_pattern = re.compile(r'^#([a-fA-F0-9]{3,6})$')
matched_results = valid_color_pattern.match(s)
if not matched_results:
raise ValidationError(_('{var_name} is not a valid hex color code').format(var_name=var_name))
return s
def check_none_or(sub_validator: Validator[ResultT]) -> Validator[ResultT]:
if USING_TYPE_STRUCTURE:
type_structure = 'none_or_' + sub_validator.type_structure # type: ignore[attr-defined] # monkey-patching
else:
type_structure = None
@set_type_structure(type_structure)
def f(var_name: str, val: object) -> Optional[ResultT]:
if val is None:
return val
else:
return sub_validator(var_name, val)
return f
@overload
def check_list(sub_validator: None, length: Optional[int]=None) -> Validator[List[object]]:
...
@overload
def check_list(sub_validator: Validator[ResultT], length: Optional[int]=None) -> Validator[List[ResultT]]:
...
def check_list(sub_validator: Optional[Validator[ResultT]]=None, length: Optional[int]=None) -> Validator[List[ResultT]]:
if USING_TYPE_STRUCTURE:
if sub_validator:
type_structure = [sub_validator.type_structure] # type: ignore[attr-defined] # monkey-patching
else:
type_structure = 'list' # type: ignore[assignment] # monkey-patching
else:
type_structure = None # type: ignore[assignment] # monkey-patching
@set_type_structure(type_structure)
def f(var_name: str, val: object) -> List[ResultT]:
if not isinstance(val, list):
raise ValidationError(_('{var_name} is not a list').format(var_name=var_name))
if length is not None and length != len(val):
raise ValidationError(_('{container} should have exactly {length} items').format(
container=var_name, length=length,
))
if sub_validator:
for i, item in enumerate(val):
vname = f'{var_name}[{i}]'
valid_item = sub_validator(vname, item)
assert item is valid_item # To justify the unchecked cast below
return cast(List[ResultT], val)
return f
@overload
def check_dict(required_keys: Iterable[Tuple[str, Validator[object]]]=[],
optional_keys: Iterable[Tuple[str, Validator[object]]]=[],
*,
_allow_only_listed_keys: bool=False) -> Validator[Dict[str, object]]:
...
@overload
def check_dict(required_keys: Iterable[Tuple[str, Validator[ResultT]]]=[],
optional_keys: Iterable[Tuple[str, Validator[ResultT]]]=[],
*,
value_validator: Validator[ResultT],
_allow_only_listed_keys: bool=False) -> Validator[Dict[str, ResultT]]:
...
def check_dict(required_keys: Iterable[Tuple[str, Validator[ResultT]]]=[],
optional_keys: Iterable[Tuple[str, Validator[ResultT]]]=[],
*,
value_validator: Optional[Validator[ResultT]]=None,
_allow_only_listed_keys: bool=False) -> Validator[Dict[str, ResultT]]:
type_structure: Dict[str, Any] = {}
@set_type_structure(type_structure)
def f(var_name: str, val: object) -> Dict[str, ResultT]:
if not isinstance(val, dict):
raise ValidationError(_('{var_name} is not a dict').format(var_name=var_name))
for k in val:
check_string(f'{var_name} key', k)
for k, sub_validator in required_keys:
if k not in val:
raise ValidationError(_('{key_name} key is missing from {var_name}').format(
key_name=k, var_name=var_name,
))
vname = f'{var_name}["{k}"]'
sub_validator(vname, val[k])
if USING_TYPE_STRUCTURE:
type_structure[k] = sub_validator.type_structure # type: ignore[attr-defined] # monkey-patching
for k, sub_validator in optional_keys:
if k in val:
vname = f'{var_name}["{k}"]'
sub_validator(vname, val[k])
if USING_TYPE_STRUCTURE:
type_structure[k] = sub_validator.type_structure # type: ignore[attr-defined] # monkey-patching
if value_validator:
for key in val:
vname = f'{var_name} contains a value that'
valid_value = value_validator(vname, val[key])
assert val[key] is valid_value # To justify the unchecked cast below
if USING_TYPE_STRUCTURE:
type_structure['any'] = value_validator.type_structure # type: ignore[attr-defined] # monkey-patching
if _allow_only_listed_keys:
required_keys_set = {x[0] for x in required_keys}
optional_keys_set = {x[0] for x in optional_keys}
delta_keys = set(val.keys()) - required_keys_set - optional_keys_set
if len(delta_keys) != 0:
raise ValidationError(_("Unexpected arguments: {}").format(", ".join(list(delta_keys))))
return cast(Dict[str, ResultT], val)
return f
def check_dict_only(required_keys: Iterable[Tuple[str, Validator[ResultT]]],
optional_keys: Iterable[Tuple[str, Validator[ResultT]]]=[]) -> Validator[Dict[str, ResultT]]:
return cast(
Validator[Dict[str, ResultT]],
check_dict(required_keys, optional_keys, _allow_only_listed_keys=True),
)
def check_union(allowed_type_funcs: Iterable[Validator[ResultT]]) -> Validator[ResultT]:
"""
Use this validator if an argument is of a variable type (e.g. processing
properties that might be strings or booleans).
`allowed_type_funcs`: the check_* validator functions for the possible data
types for this variable.
"""
if USING_TYPE_STRUCTURE:
type_structure = f'any("{[x.type_structure for x in allowed_type_funcs]}")' # type: ignore[attr-defined] # monkey-patching
else:
type_structure = None # type: ignore[assignment] # monkey-patching
@set_type_structure(type_structure)
def enumerated_type_check(var_name: str, val: object) -> ResultT:
for func in allowed_type_funcs:
try:
return func(var_name, val)
except ValidationError:
pass
raise ValidationError(_('{var_name} is not an allowed_type').format(var_name=var_name))
return enumerated_type_check
def equals(expected_val: ResultT) -> Validator[ResultT]:
@set_type_structure(f'equals("{str(expected_val)}")')
def f(var_name: str, val: object) -> ResultT:
if val != expected_val:
raise ValidationError(_('{variable} != {expected_value} ({value} is wrong)').format(
variable=var_name, expected_value=expected_val, value=val,
))
return cast(ResultT, val)
return f
@set_type_structure('str')
def validate_login_email(email: str) -> None:
try:
validate_email(email)
except ValidationError as err:
raise JsonableError(str(err.message))
@set_type_structure('str')
def check_url(var_name: str, val: object) -> str:
# First, ensure val is a string
s = check_string(var_name, val)
# Now, validate as URL
validate = URLValidator()
try:
validate(s)
return s
except ValidationError:
raise ValidationError(_('{var_name} is not a URL').format(var_name=var_name))
@set_type_structure('str')
def check_external_account_url_pattern(var_name: str, val: object) -> str:
s = check_string(var_name, val)
if s.count('%(username)s') != 1:
raise ValidationError(_('Malformed URL pattern.'))
url_val = s.replace('%(username)s', 'username')
check_url(var_name, url_val)
return s
def validate_choice_field_data(field_data: ProfileFieldData) -> Dict[str, Dict[str, str]]:
"""
This function is used to validate the data sent to the server while
creating/editing choices of the choice field in Organization settings.
"""
validator = check_dict_only([
('text', check_required_string),
('order', check_required_string),
])
for key, value in field_data.items():
if not key.strip():
raise ValidationError(_("'{item}' cannot be blank.").format(item='value'))
valid_value = validator('field_data', value)
assert value is valid_value # To justify the unchecked cast below
return cast(Dict[str, Dict[str, str]], field_data)
def validate_choice_field(var_name: str, field_data: str, value: object) -> str:
"""
This function is used to validate the value selected by the user against a
choice field. This is not used to validate admin data.
"""
s = check_string(var_name, value)
field_data_dict = ujson.loads(field_data)
if s not in field_data_dict:
msg = _("'{value}' is not a valid choice for '{field_name}'.")
raise ValidationError(msg.format(value=value, field_name=var_name))
return s
def check_widget_content(widget_content: object) -> Dict[str, Any]:
if not isinstance(widget_content, dict):
raise ValidationError('widget_content is not a dict')
if 'widget_type' not in widget_content:
raise ValidationError('widget_type is not in widget_content')
if 'extra_data' not in widget_content:
raise ValidationError('extra_data is not in widget_content')
widget_type = widget_content['widget_type']
extra_data = widget_content['extra_data']
if not isinstance(extra_data, dict):
raise ValidationError('extra_data is not a dict')
if widget_type == 'zform':
if 'type' not in extra_data:
raise ValidationError('zform is missing type field')
if extra_data['type'] == 'choices':
check_choices = check_list(
check_dict([
('short_name', check_string),
('long_name', check_string),
('reply', check_string),
]),
)
checker = check_dict([
('heading', check_string),
('choices', check_choices),
])
checker('extra_data', extra_data)
return widget_content
raise ValidationError('unknown zform type: ' + extra_data['type'])
raise ValidationError('unknown widget type: ' + widget_type)
# Converter functions for use with has_request_variables
@set_type_structure('int')
def to_non_negative_int(s: str, max_int_size: int=2**32-1) -> int:
x = int(s)
if x < 0:
raise ValueError("argument is negative")
if x > max_int_size:
raise ValueError(f'{x} is too large (max {max_int_size})')
return x
def to_positive_or_allowed_int(allowed_integer: int) -> Callable[[str], int]:
@set_type_structure('int')
def convertor(s: str) -> int:
x = int(s)
if x == allowed_integer:
return x
if x == 0:
raise ValueError("argument is 0")
return to_non_negative_int(s)
return convertor
@set_type_structure('any(List[int], str)]')
def check_string_or_int_list(var_name: str, val: object) -> Union[str, List[int]]:
if isinstance(val, str):
return val
if not isinstance(val, list):
raise ValidationError(_('{var_name} is not a string or an integer list').format(var_name=var_name))
return check_list(check_int)(var_name, val)
@set_type_structure('any(int, str)')
def check_string_or_int(var_name: str, val: object) -> Union[str, int]:
if isinstance(val, str) or isinstance(val, int):
return val
raise ValidationError(_('{var_name} is not a string or integer').format(var_name=var_name))