bazarr/libs/werkzeug/debug/__init__.py

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)