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