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# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
"""Mask sensitive information from logs"""
import collections
import logging
import re
import sys
from typing import Any, Dict, Iterable, List, Optional, Set, TextIO, Tuple, TypeVar, Union

from airflow import settings
from airflow.compat.functools import cache, cached_property

Redactable = TypeVar("Redactable", str, Dict[Any, Any], Tuple[Any, ...], List[Any])
Redacted = Union[Redactable, str]

log = logging.getLogger(__name__)

DEFAULT_SENSITIVE_FIELDS = frozenset(
    {
        'access_token',
        'api_key',
        'apikey',
        'authorization',
        'passphrase',
        'passwd',
        'password',
        'private_key',
        'secret',
        'token',
        'keyfile_dict',
        'service_account',
    }
)
"""Names of fields (Connection extra, Variable key name etc.) that are deemed sensitive"""

SECRETS_TO_SKIP_MASKING_FOR_TESTS = {'airflow'}


@cache
def get_sensitive_variables_fields():
    """Get comma-separated sensitive Variable Fields from airflow.cfg."""
    from airflow.configuration import conf

    sensitive_fields = DEFAULT_SENSITIVE_FIELDS.copy()
    sensitive_variable_fields = conf.get('core', 'sensitive_var_conn_names')
    if sensitive_variable_fields:
        sensitive_fields |= frozenset({field.strip() for field in sensitive_variable_fields.split(',')})
    return sensitive_fields


def should_hide_value_for_key(name):
    """Should the value for this given name (Variable name, or key in conn.extra_dejson) be hidden"""
    from airflow import settings

    if isinstance(name, str) and settings.HIDE_SENSITIVE_VAR_CONN_FIELDS:
        name = name.strip().lower()
        return any(s in name for s in get_sensitive_variables_fields())
    return False


def mask_secret(secret: Union[str, dict, Iterable], name: Optional[str] = None) -> None:
    """
    Mask a secret from appearing in the task logs.

    If ``name`` is provided, then it will only be masked if the name matches
    one of the configured "sensitive" names.

    If ``secret`` is a dict or a iterable (excluding str) then it will be
    recursively walked and keys with sensitive names will be hidden.
    """
    # Filtering all log messages is not a free process, so we only do it when
    # running tasks
    if not secret:
        return

    _secrets_masker().add_mask(secret, name)


def redact(value: Redactable, name: Optional[str] = None) -> Redacted:
    """Redact any secrets found in ``value``."""
    return _secrets_masker().redact(value, name)


@cache
def _secrets_masker() -> "SecretsMasker":
    for flt in logging.getLogger('airflow.task').filters:
        if isinstance(flt, SecretsMasker):
            return flt
    raise RuntimeError(
        "Logging Configuration Error! No SecretsMasker found! If you have custom logging, please make "
        "sure you configure it taking airflow configuration as a base as explained at "
        "https://airflow.apache.org/docs/apache-airflow/stable/logging-monitoring/logging-tasks.html"
        "#advanced-configuration"
    )


class SecretsMasker(logging.Filter):
    """Redact secrets from logs"""

    replacer: Optional[re.Pattern] = None
    patterns: Set[str]

    ALREADY_FILTERED_FLAG = "__SecretsMasker_filtered"
    MAX_RECURSION_DEPTH = 5

    def __init__(self):
        super().__init__()
        self.patterns = set()

    @cached_property
    def _record_attrs_to_ignore(self) -> Iterable[str]:
        # Doing log.info(..., extra={'foo': 2}) sets extra properties on
        # record, i.e. record.foo. And we need to filter those too. Fun
        #
        # Create a record, and look at what attributes are on it, and ignore
        # all the default ones!

        record = logging.getLogRecordFactory()(
            # name, level, pathname, lineno, msg, args, exc_info, func=None, sinfo=None,
            "x",
            logging.INFO,
            __file__,
            1,
            "",
            tuple(),
            exc_info=None,
            func="funcname",
        )
        return frozenset(record.__dict__).difference({'msg', 'args'})

    def _redact_exception_with_context(self, exception):
        # Exception class may not be modifiable (e.g. declared by an
        # extension module such as JDBC).
        try:
            exception.args = (self.redact(v) for v in exception.args)
        except AttributeError:
            pass
        if exception.__context__:
            self._redact_exception_with_context(exception.__context__)
        if exception.__cause__ and exception.__cause__ is not exception.__context__:
            self._redact_exception_with_context(exception.__cause__)

    def filter(self, record) -> bool:
        if settings.MASK_SECRETS_IN_LOGS is not True:
            return True

        if self.ALREADY_FILTERED_FLAG in record.__dict__:
            # Filters are attached to multiple handlers and logs, keep a
            # "private" flag that stops us needing to process it more than once
            return True

        if self.replacer:
            for k, v in record.__dict__.items():
                if k in self._record_attrs_to_ignore:
                    continue
                record.__dict__[k] = self.redact(v)
            if record.exc_info and record.exc_info[1] is not None:
                exc = record.exc_info[1]
                self._redact_exception_with_context(exc)
        record.__dict__[self.ALREADY_FILTERED_FLAG] = True

        return True

    def _redact_all(self, item: Redactable, depth: int) -> Redacted:
        if depth > self.MAX_RECURSION_DEPTH or isinstance(item, str):
            return '***'
        if isinstance(item, dict):
            return {dict_key: self._redact_all(subval, depth + 1) for dict_key, subval in item.items()}
        elif isinstance(item, (tuple, set)):
            # Turn set in to tuple!
            return tuple(self._redact_all(subval, depth + 1) for subval in item)
        elif isinstance(item, list):
            return list(self._redact_all(subval, depth + 1) for subval in item)
        else:
            return item

    def _redact(self, item: Redactable, name: Optional[str], depth: int) -> Redacted:
        # Avoid spending too much effort on redacting on deeply nested
        # structures. This also avoid infinite recursion if a structure has
        # reference to self.
        if depth > self.MAX_RECURSION_DEPTH:
            return item
        try:
            if name and should_hide_value_for_key(name):
                return self._redact_all(item, depth)
            if isinstance(item, dict):
                return {
                    dict_key: self._redact(subval, name=dict_key, depth=(depth + 1))
                    for dict_key, subval in item.items()
                }
            elif isinstance(item, str):
                if self.replacer:
                    # We can't replace specific values, but the key-based redacting
                    # can still happen, so we can't short-circuit, we need to walk
                    # the structure.
                    return self.replacer.sub('***', item)
                return item
            elif isinstance(item, (tuple, set)):
                # Turn set in to tuple!
                return tuple(self._redact(subval, name=None, depth=(depth + 1)) for subval in item)
            elif isinstance(item, list):
                return [self._redact(subval, name=None, depth=(depth + 1)) for subval in item]
            else:
                return item
        # I think this should never happen, but it does not hurt to leave it just in case
        # Well. It happened (see https://github.com/apache/airflow/issues/19816#issuecomment-983311373)
        # but it caused infinite recursion, so we need to cast it to str first.
        except Exception as e:
            log.warning(
                "Unable to redact %s, please report this via <https://github.com/apache/airflow/issues>. "
                "Error was: %s: %s",
                repr(item),
                type(e).__name__,
                str(e),
            )
            return item

    def redact(self, item: Redactable, name: Optional[str] = None) -> Redacted:
        """Redact an any secrets found in ``item``, if it is a string.

        If ``name`` is given, and it's a "sensitive" name (see
        :func:`should_hide_value_for_key`) then all string values in the item
        is redacted.
        """
        return self._redact(item, name, depth=0)

    def add_mask(self, secret: Union[str, dict, Iterable], name: Optional[str] = None):
        """Add a new secret to be masked to this filter instance."""
        from airflow.configuration import conf

        test_mode: bool = conf.getboolean('core', 'unit_test_mode')
        if isinstance(secret, dict):
            for k, v in secret.items():
                self.add_mask(v, k)
        elif isinstance(secret, str):
            if not secret or (test_mode and secret in SECRETS_TO_SKIP_MASKING_FOR_TESTS):
                return
            pattern = re.escape(secret)
            if pattern not in self.patterns and (not name or should_hide_value_for_key(name)):
                self.patterns.add(pattern)
                self.replacer = re.compile('|'.join(self.patterns))
        elif isinstance(secret, collections.abc.Iterable):
            for v in secret:
                self.add_mask(v, name)


class RedactedIO(TextIO):
    """IO class that redacts values going into stdout.

    Expected usage::

        with contextlib.redirect_stdout(RedactedIO()):
            ...  # Writes to stdout will be redacted.
    """

    def __init__(self):
        self.target = sys.stdout

    def write(self, s: str) -> int:
        s = redact(s)
        return self.target.write(s)

    def flush(self) -> None:
        return self.target.flush()
