lucasvl.nl/lib/python3.11/site-packages/werkzeug/debug/__init__.py

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2024-03-04 21:31:20 -06:00
from __future__ import annotations
import getpass
import hashlib
import json
import os
import pkgutil
import re
import sys
import time
import typing as t
import uuid
from contextlib import ExitStack
from io import BytesIO
from itertools import chain
from os.path import basename
from os.path import join
from zlib import adler32
from .._internal import _log
from ..exceptions import NotFound
from ..http import parse_cookie
from ..security import gen_salt
from ..utils import send_file
from ..wrappers.request import Request
from ..wrappers.response import Response
from .console import Console
from .tbtools import DebugFrameSummary
from .tbtools import DebugTraceback
from .tbtools import render_console_html
if t.TYPE_CHECKING:
from _typeshed.wsgi import StartResponse
from _typeshed.wsgi import WSGIApplication
from _typeshed.wsgi import WSGIEnvironment
# A week
PIN_TIME = 60 * 60 * 24 * 7
def hash_pin(pin: str) -> str:
return hashlib.sha1(f"{pin} added salt".encode("utf-8", "replace")).hexdigest()[:12]
_machine_id: str | bytes | None = None
def get_machine_id() -> str | bytes | None:
global _machine_id
if _machine_id is not None:
return _machine_id
def _generate() -> str | bytes | None:
linux = b""
# machine-id is stable across boots, boot_id is not.
for filename in "/etc/machine-id", "/proc/sys/kernel/random/boot_id":
try:
with open(filename, "rb") as f:
value = f.readline().strip()
except OSError:
continue
if value:
linux += value
break
# Containers share the same machine id, add some cgroup
# information. This is used outside containers too but should be
# relatively stable across boots.
try:
with open("/proc/self/cgroup", "rb") as f:
linux += f.readline().strip().rpartition(b"/")[2]
except OSError:
pass
if linux:
return linux
# On OS X, use ioreg to get the computer's serial number.
try:
# subprocess may not be available, e.g. Google App Engine
# https://github.com/pallets/werkzeug/issues/925
from subprocess import Popen, PIPE
dump = Popen(
["ioreg", "-c", "IOPlatformExpertDevice", "-d", "2"], stdout=PIPE
).communicate()[0]
match = re.search(b'"serial-number" = <([^>]+)', dump)
if match is not None:
return match.group(1)
except (OSError, ImportError):
pass
# On Windows, use winreg to get the machine guid.
if sys.platform == "win32":
import winreg
try:
with winreg.OpenKey(
winreg.HKEY_LOCAL_MACHINE,
"SOFTWARE\\Microsoft\\Cryptography",
0,
winreg.KEY_READ | winreg.KEY_WOW64_64KEY,
) as rk:
guid: str | bytes
guid_type: int
guid, guid_type = winreg.QueryValueEx(rk, "MachineGuid")
if guid_type == winreg.REG_SZ:
return guid.encode("utf-8")
return guid
except OSError:
pass
return None
_machine_id = _generate()
return _machine_id
class _ConsoleFrame:
"""Helper class so that we can reuse the frame console code for the
standalone console.
"""
def __init__(self, namespace: dict[str, t.Any]):
self.console = Console(namespace)
self.id = 0
def eval(self, code: str) -> t.Any:
return self.console.eval(code)
def get_pin_and_cookie_name(
app: WSGIApplication,
) -> tuple[str, str] | tuple[None, None]:
"""Given an application object this returns a semi-stable 9 digit pin
code and a random key. The hope is that this is stable between
restarts to not make debugging particularly frustrating. If the pin
was forcefully disabled this returns `None`.
Second item in the resulting tuple is the cookie name for remembering.
"""
pin = os.environ.get("WERKZEUG_DEBUG_PIN")
rv = None
num = None
# Pin was explicitly disabled
if pin == "off":
return None, None
# Pin was provided explicitly
if pin is not None and pin.replace("-", "").isdecimal():
# If there are separators in the pin, return it directly
if "-" in pin:
rv = pin
else:
num = pin
modname = getattr(app, "__module__", t.cast(object, app).__class__.__module__)
username: str | None
try:
# getuser imports the pwd module, which does not exist in Google
# App Engine. It may also raise a KeyError if the UID does not
# have a username, such as in Docker.
username = getpass.getuser()
except (ImportError, KeyError):
username = None
mod = sys.modules.get(modname)
# This information only exists to make the cookie unique on the
# computer, not as a security feature.
probably_public_bits = [
username,
modname,
getattr(app, "__name__", type(app).__name__),
getattr(mod, "__file__", None),
]
# This information is here to make it harder for an attacker to
# guess the cookie name. They are unlikely to be contained anywhere
# within the unauthenticated debug page.
private_bits = [str(uuid.getnode()), get_machine_id()]
h = hashlib.sha1()
for bit in chain(probably_public_bits, private_bits):
if not bit:
continue
if isinstance(bit, str):
bit = bit.encode("utf-8")
h.update(bit)
h.update(b"cookiesalt")
cookie_name = f"__wzd{h.hexdigest()[:20]}"
# If we need to generate a pin we salt it a bit more so that we don't
# end up with the same value and generate out 9 digits
if num is None:
h.update(b"pinsalt")
num = f"{int(h.hexdigest(), 16):09d}"[:9]
# Format the pincode in groups of digits for easier remembering if
# we don't have a result yet.
if rv is None:
for group_size in 5, 4, 3:
if len(num) % group_size == 0:
rv = "-".join(
num[x : x + group_size].rjust(group_size, "0")
for x in range(0, len(num), group_size)
)
break
else:
rv = num
return rv, cookie_name
class DebuggedApplication:
"""Enables debugging support for a given application::
from werkzeug.debug import DebuggedApplication
from myapp import app
app = DebuggedApplication(app, evalex=True)
The ``evalex`` argument allows evaluating expressions in any frame
of a traceback. This works by preserving each frame with its local
state. Some state, such as context globals, cannot be restored with
the frame by default. When ``evalex`` is enabled,
``environ["werkzeug.debug.preserve_context"]`` will be a callable
that takes a context manager, and can be called multiple times.
Each context manager will be entered before evaluating code in the
frame, then exited again, so they can perform setup and cleanup for
each call.
:param app: the WSGI application to run debugged.
:param evalex: enable exception evaluation feature (interactive
debugging). This requires a non-forking server.
:param request_key: The key that points to the request object in this
environment. This parameter is ignored in current
versions.
:param console_path: the URL for a general purpose console.
:param console_init_func: the function that is executed before starting
the general purpose console. The return value
is used as initial namespace.
:param show_hidden_frames: by default hidden traceback frames are skipped.
You can show them by setting this parameter
to `True`.
:param pin_security: can be used to disable the pin based security system.
:param pin_logging: enables the logging of the pin system.
.. versionchanged:: 2.2
Added the ``werkzeug.debug.preserve_context`` environ key.
"""
_pin: str
_pin_cookie: str
def __init__(
self,
app: WSGIApplication,
evalex: bool = False,
request_key: str = "werkzeug.request",
console_path: str = "/console",
console_init_func: t.Callable[[], dict[str, t.Any]] | None = None,
show_hidden_frames: bool = False,
pin_security: bool = True,
pin_logging: bool = True,
) -> None:
if not console_init_func:
console_init_func = None
self.app = app
self.evalex = evalex
self.frames: dict[int, DebugFrameSummary | _ConsoleFrame] = {}
self.frame_contexts: dict[int, list[t.ContextManager[None]]] = {}
self.request_key = request_key
self.console_path = console_path
self.console_init_func = console_init_func
self.show_hidden_frames = show_hidden_frames
self.secret = gen_salt(20)
self._failed_pin_auth = 0
self.pin_logging = pin_logging
if pin_security:
# Print out the pin for the debugger on standard out.
if os.environ.get("WERKZEUG_RUN_MAIN") == "true" and pin_logging:
_log("warning", " * Debugger is active!")
if self.pin is None:
_log("warning", " * Debugger PIN disabled. DEBUGGER UNSECURED!")
else:
_log("info", " * Debugger PIN: %s", self.pin)
else:
self.pin = None
@property
def pin(self) -> str | None:
if not hasattr(self, "_pin"):
pin_cookie = get_pin_and_cookie_name(self.app)
self._pin, self._pin_cookie = pin_cookie # type: ignore
return self._pin
@pin.setter
def pin(self, value: str) -> None:
self._pin = value
@property
def pin_cookie_name(self) -> str:
"""The name of the pin cookie."""
if not hasattr(self, "_pin_cookie"):
pin_cookie = get_pin_and_cookie_name(self.app)
self._pin, self._pin_cookie = pin_cookie # type: ignore
return self._pin_cookie
def debug_application(
self, environ: WSGIEnvironment, start_response: StartResponse
) -> t.Iterator[bytes]:
"""Run the application and conserve the traceback frames."""
contexts: list[t.ContextManager[t.Any]] = []
if self.evalex:
environ["werkzeug.debug.preserve_context"] = contexts.append
app_iter = None
try:
app_iter = self.app(environ, start_response)
yield from app_iter
if hasattr(app_iter, "close"):
app_iter.close()
except Exception as e:
if hasattr(app_iter, "close"):
app_iter.close() # type: ignore
tb = DebugTraceback(e, skip=1, hide=not self.show_hidden_frames)
for frame in tb.all_frames:
self.frames[id(frame)] = frame
self.frame_contexts[id(frame)] = contexts
is_trusted = bool(self.check_pin_trust(environ))
html = tb.render_debugger_html(
evalex=self.evalex,
secret=self.secret,
evalex_trusted=is_trusted,
)
response = Response(html, status=500, mimetype="text/html")
try:
yield from response(environ, start_response)
except Exception:
# if we end up here there has been output but an error
# occurred. in that situation we can do nothing fancy any
# more, better log something into the error log and fall
# back gracefully.
environ["wsgi.errors"].write(
"Debugging middleware caught exception in streamed "
"response at a point where response headers were already "
"sent.\n"
)
environ["wsgi.errors"].write("".join(tb.render_traceback_text()))
def execute_command( # type: ignore[return]
self,
request: Request,
command: str,
frame: DebugFrameSummary | _ConsoleFrame,
) -> Response:
"""Execute a command in a console."""
contexts = self.frame_contexts.get(id(frame), [])
with ExitStack() as exit_stack:
for cm in contexts:
exit_stack.enter_context(cm)
return Response(frame.eval(command), mimetype="text/html")
def display_console(self, request: Request) -> Response:
"""Display a standalone shell."""
if 0 not in self.frames:
if self.console_init_func is None:
ns = {}
else:
ns = dict(self.console_init_func())
ns.setdefault("app", self.app)
self.frames[0] = _ConsoleFrame(ns)
is_trusted = bool(self.check_pin_trust(request.environ))
return Response(
render_console_html(secret=self.secret, evalex_trusted=is_trusted),
mimetype="text/html",
)
def get_resource(self, request: Request, filename: str) -> Response:
"""Return a static resource from the shared folder."""
path = join("shared", basename(filename))
try:
data = pkgutil.get_data(__package__, path)
except OSError:
return NotFound() # type: ignore[return-value]
else:
if data is None:
return NotFound() # type: ignore[return-value]
etag = str(adler32(data) & 0xFFFFFFFF)
return send_file(
BytesIO(data), request.environ, download_name=filename, etag=etag
)
def check_pin_trust(self, environ: WSGIEnvironment) -> bool | None:
"""Checks if the request passed the pin test. This returns `True` if the
request is trusted on a pin/cookie basis and returns `False` if not.
Additionally if the cookie's stored pin hash is wrong it will return
`None` so that appropriate action can be taken.
"""
if self.pin is None:
return True
val = parse_cookie(environ).get(self.pin_cookie_name)
if not val or "|" not in val:
return False
ts_str, pin_hash = val.split("|", 1)
try:
ts = int(ts_str)
except ValueError:
return False
if pin_hash != hash_pin(self.pin):
return None
return (time.time() - PIN_TIME) < ts
def _fail_pin_auth(self) -> None:
time.sleep(5.0 if self._failed_pin_auth > 5 else 0.5)
self._failed_pin_auth += 1
def pin_auth(self, request: Request) -> Response:
"""Authenticates with the pin."""
exhausted = False
auth = False
trust = self.check_pin_trust(request.environ)
pin = t.cast(str, self.pin)
# If the trust return value is `None` it means that the cookie is
# set but the stored pin hash value is bad. This means that the
# pin was changed. In this case we count a bad auth and unset the
# cookie. This way it becomes harder to guess the cookie name
# instead of the pin as we still count up failures.
bad_cookie = False
if trust is None:
self._fail_pin_auth()
bad_cookie = True
# If we're trusted, we're authenticated.
elif trust:
auth = True
# If we failed too many times, then we're locked out.
elif self._failed_pin_auth > 10:
exhausted = True
# Otherwise go through pin based authentication
else:
entered_pin = request.args["pin"]
if entered_pin.strip().replace("-", "") == pin.replace("-", ""):
self._failed_pin_auth = 0
auth = True
else:
self._fail_pin_auth()
rv = Response(
json.dumps({"auth": auth, "exhausted": exhausted}),
mimetype="application/json",
)
if auth:
rv.set_cookie(
self.pin_cookie_name,
f"{int(time.time())}|{hash_pin(pin)}",
httponly=True,
samesite="Strict",
secure=request.is_secure,
)
elif bad_cookie:
rv.delete_cookie(self.pin_cookie_name)
return rv
def log_pin_request(self) -> Response:
"""Log the pin if needed."""
if self.pin_logging and self.pin is not None:
_log(
"info", " * To enable the debugger you need to enter the security pin:"
)
_log("info", " * Debugger pin code: %s", self.pin)
return Response("")
def __call__(
self, environ: WSGIEnvironment, start_response: StartResponse
) -> t.Iterable[bytes]:
"""Dispatch the requests."""
# important: don't ever access a function here that reads the incoming
# form data! Otherwise the application won't have access to that data
# any more!
request = Request(environ)
response = self.debug_application
if request.args.get("__debugger__") == "yes":
cmd = request.args.get("cmd")
arg = request.args.get("f")
secret = request.args.get("s")
frame = self.frames.get(request.args.get("frm", type=int)) # type: ignore
if cmd == "resource" and arg:
response = self.get_resource(request, arg) # type: ignore
elif cmd == "pinauth" and secret == self.secret:
response = self.pin_auth(request) # type: ignore
elif cmd == "printpin" and secret == self.secret:
response = self.log_pin_request() # type: ignore
elif (
self.evalex
and cmd is not None
and frame is not None
and self.secret == secret
and self.check_pin_trust(environ)
):
response = self.execute_command(request, cmd, frame) # type: ignore
elif (
self.evalex
and self.console_path is not None
and request.path == self.console_path
):
response = self.display_console(request) # type: ignore
return response(environ, start_response)