#28628: Audit for and abolish all use of '\d' in regexes
-------------------------------------+-------------------------------------
Reporter: James Bennett | Owner: Ad
Type: | Timmering
Cleanup/optimization | Status: assigned
Component: Core (Other) | Version: dev
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 1
Easy pickings: 0 | UI/UX: 0
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Old description:
> Now that we're in the 2.0 release cycle and Python 3 only, any examples
> or code in Django using a `\d` in a regex should be replaced with
> `[0-9]`, as `\d` on Python 3 matches any character with Unicode category
> [Nd], which is almost certainly not what people expect. Changing to
> explicit `[0-9]`, perhaps with a note about why it should be preferred,
> would be better.
New description:
Now that we're in the 2.0 release cycle and Python 3 only, any examples or
code in Django using a `\d` in a regex should be replaced with `[0-9]`, as
`\d` on Python 3 matches any character with Unicode category [Nd], which
is almost certainly not what people expect. Changing to explicit `[0-9]`,
perhaps with a note about why it should be preferred, would be better.
Inventory of current uses & recommendations (with recommendation &
updating table reflecting feedback):
||= **Module** =||= **Description** =||
|| django.contrib.admin.options || In internal function
`_get_edited_object_pks`. \\Obtains PKs for edited objects through the
ModelAdmin. POST should be machine-generated (through the admin interface)
and not based on human input, so typically will be ASCII input. \\Changing
to more restrictive regex unlikely to hurt any users, but doesn't add
value either. ||
|| django.contrib.gis.geometry || Used to process GIS geometry
data.\\Changing to more restrictive regex unlikely to hurt any users, but
doesn't add value either. ||
|| django.contrib.gis.db.backends.postgis.operations || Used to obtain
individual decimal components from the gettext version, eg. 1.2.3.
\\Changing to a more restrictive regex is unlikely to hurt any users, but
doesn't add value either. ||
|| django.contrib.gis.gdal.libgdal || Used to obtain individual decimal
components from the gettext version, eg. 1.2.3.\\\\Changing to a more
restrictive regex is unlikely to hurt any users, but doesn't add value
either. ||
|| django.contrib.gis.geos.geometry || Used to process GIS geometry EWKT
data. Resulting string is cast with `int()`.\\\\Changing to more
restrictive regex unlikely to hurt any users, but doesn't add value
either. ||
|| django.contrib.humanize.templatetags.humanize || Used in intcomma
filter, that formats ints like 3000 as 3,000. \\\\Tested in
`tests.humanize_tests.tests.HumanizeTests.test_intcomma`.\\\\Using a more
restrictive regex could possibly hurt users. Instead added tests to ensure
this works with non-ASCII unicode. ||
|| django.core.validators || (1) Used in URLValidator for `ipv4_re` port
component in regex. Being more restrictive to capture valid IPv4 and ports
seems useful, and not likely to be a breaking change. **Change** to
`[0-9]` for consistency with other parts of the regex.
|| django.core.validators || (2) Used in `integer_validator` and
`validate_integer`. Any number captured by d can be cast to an int and
therefore no value is added (and likely users might be hurt) by
restricting this to [0-9]). **Do not change**. ||
|| django.core.validators || (3) Used in `int_list_validator`, which does
not use `int()` → **Change** to `[0-9]`. ||
|| django.core.management.commands.makemessages || Used to obtain
individual decimal components from the gettext version, eg.
1.2.3.\\Changing to a more restrictive regex is unlikely to hurt any
users, but doesn't add value either. ||
|| django.core.management.commands.runserver || Used to determine valid
IPv4 addresses and valid port numbers. \\WSGI server seems to work fine
even if for example 127.0.０.1 (incl a non-ASCII 0) is provided, and it
seems the integers are properly cast -- so there would be little advantage
to users to change this to a more restrictive regex. ||
|| django.db.backends.mysql.base || Used to obtain individual decimal
components from a version, eg. 1.2.3. Changing to a more restrictive regex
is unlikely to hurt any users, but doesn't add value either. ||
|| django.db.backends.sqlite3.introspection || Extracts the size number
from a `varchar(11)` type name. \\\\Changing to a more restrictive regex
is unlikely to hurt any users, but doesn't add value either. ||
|| django.db.migrations.autodetector || Used to extract the number from a
migration filename. Unlikely to contain non-ASCII unless intentionally
changed by a dev.\\Changing to a more restrictive regex is unlikely to
hurt any users, but doesn't add value either. ||
|| django.db.migrations.writer || Used to sort imports in migrations,
tested in tests.migrations.test_writer, see test_sorted_imports. Unclear
to me what the decimal portion of the regex represents, however I don't
see value in restricting to more restrictive regex. ||
|| django.forms.widgets || Used by SelectDateWidget to match a "YYYY-MM-
DD" date pattern. When matched integers are cast with `int(val)` and
therefore correctly processed if input was in non-ASCII Unicode decimals.
\\**Changing** to a more restrictive regexp to match HTML5 validation
rules, see https://html.spec.whatwg.org/#valid-date-string ||
|| django.http.request || Used in split_domain_port to split a domain name
and port ("www.example.com:8080"). \\The port number should be cast to an
int (in which case, no problem!) - however in reality isn't currently
being used in any code path, and both domain and port are returned as str.
**Changed** to match other components of the regex. ||
|| django.template.base || Used in FilterExpression regex to match filters
in templates. Arguments are passed on to individual filters. Where an int
is expected, filters will cast using `int(x)` regardless so would process
correctly. Using a more restrictive regex could possibly hurt users
inadvertently using non-ASCII decimals in filter parameters. **Do not
change**. ||
|| django.template.defaultfilters || Used in default title filter to
change a letter after a decimal back back to lower case. Eg. `53RD ⇒ 53Rd
⇒ 53rd`. Changing this could have unexpected results for users, and no
value is gained. **Do not change**. ||
|| django.test.client || Parses `charset` within the `Content-Type` header
of `test.client.RequestFactory`. Strictly spoken the HTTP spec requires
ASCII characters. **Change** for consistency as it reflects HTTP specs,
however does not add much value. ||
|| django.utils.dateparse || Used for parsing date and time fields, in
parsing string representations in the to_python implementations on
DateField and DateTimeField in db.models. Decimals are extracted with
regex, and downcast with `int(v)`. In normal usage these are unlikely to
contain non-ASCII numbers, but if using legacy DBs it is quite possible
data might have non-ASCII versions of numbers as well. Using a more
restrictive regex could possibly hurt users. **Do not change**.
|| django.utils.http || Used in data parsing according to RFC1123, RFC850
and asctime. Requires ASCII decimals as defined in RFC822:
https://datatracker.ietf.org/doc/html/rfc822#appendix-D with "DIGIT = <any
ASCII decimal digit> ; ( 60- 71, 48.- 57.)". The additional value of a
more restrictive regex is not 100% evident, but it doesn't hurt to change
the implementation to be closer to the specifications. ||
|| django.utils.version || Used to obtain individual decimal components
from a version, eg. 1.2.3. Changing to a more restrictive regex is
unlikely to hurt any users, but doesn't add value either. ||
|| django.utils.translation.trans_real || Used in regex to parse HTTP
Accept-Language header. HTTP requires ASCII decimals. Example: `Accept-
Language: pt,en-US;q=0.8,en;q=0.6,ru;q=0.4`. **Change** to more
restrictive regex to match specs in
https://datatracker.ietf.org/doc/html/rfc2616#section-3.9 . ||
|| django.views.i18n || `JavaScriptCatalog._num_plurals()`. Used to parse
nplurals setting (see
[https://www.gnu.org/software/gettext/manual/html_node/Plural-forms.html
doc]). Regex match is cast with `int(x)`. Intent is likely an ASCII
decimal number ("nplurals value must be a decimal number which …"),
however restricting the regex does not add any value. **Do not change**.
||
--
Comment (by Ad Timmering):
Description updated.
--
Ticket URL: <https://code.djangoproject.com/ticket/28628#comment:20>
Django <https://code.djangoproject.com/>
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