Source code for requests_cache.cache_keys

"""Internal utilities for generating the cache keys that are used to match requests

.. automodsumm:: requests_cache.cache_keys
   :functions-only:
   :nosignatures:
"""
from __future__ import annotations

import json
from hashlib import blake2b
from logging import getLogger
from typing import TYPE_CHECKING, Dict, Iterable, List, Mapping, Optional, Union
from urllib.parse import parse_qsl, urlencode, urlparse, urlunparse

from requests import Request, Session
from requests.models import CaseInsensitiveDict
from url_normalize import url_normalize

from ._utils import get_valid_kwargs

if TYPE_CHECKING:
    from .models import AnyPreparedRequest, AnyRequest, CachedResponse

__all__ = ['create_key', 'normalize_request']
# Request headers that are always excluded from cache keys, but not redacted from cached responses
DEFAULT_EXCLUDE_HEADERS = {'Cache-Control', 'If-None-Match', 'If-Modified-Since'}

ParamList = Optional[Iterable[str]]
RequestContent = Union[Mapping, str, bytes]

logger = getLogger(__name__)


[docs]def create_key( request: AnyRequest = None, ignored_parameters: ParamList = None, match_headers: Union[ParamList, bool] = False, **request_kwargs, ) -> str: """Create a normalized cache key from either a request object or :py:class:`~requests.Request` arguments Args: request: Request object to generate a cache key from ignored_parameters: Request parames, headers, and/or body params to not match against match_headers: Match only the specified headers, or ``True`` to match all headers request_kwargs: Request arguments to generate a cache key from """ # Convert raw request arguments into a request object, if needed if not request: request = Request(**get_valid_kwargs(Request.__init__, request_kwargs)) # Normalize and gather all relevant request info to match against request = normalize_request(request, ignored_parameters) key_parts = [ request.method or '', request.url, request.body or '', request_kwargs.get('verify', True), *get_matched_headers(request.headers, match_headers), ] # Generate a hash based on this info key = blake2b(digest_size=8) for part in key_parts: key.update(encode(part)) return key.hexdigest()
def get_matched_headers( headers: CaseInsensitiveDict, match_headers: Union[ParamList, bool] ) -> List[str]: """Get only the headers we should match against as a list of ``k=v`` strings, given an optional include list. """ if not match_headers: return [] if isinstance(match_headers, Iterable): included = set(match_headers) - DEFAULT_EXCLUDE_HEADERS else: included = set(headers) - DEFAULT_EXCLUDE_HEADERS return [ f'{k.lower()}={headers[k]}' for k in sorted(included, key=lambda x: x.lower()) if k in headers ]
[docs]def normalize_request(request: AnyRequest, ignored_parameters: ParamList) -> AnyPreparedRequest: """Normalize and remove ignored parameters from request URL, body, and headers. This is used for both: * Increasing cache hits by generating more precise cache keys * Redacting potentially sensitive info from cached requests Args: request: Request object to normalize ignored_parameters: Request parames, headers, and/or body params to not match against and to remove from the request """ if isinstance(request, Request): norm_request: AnyPreparedRequest = Session().prepare_request(request) else: norm_request = request.copy() norm_request.method = (norm_request.method or '').upper() norm_request.url = normalize_url(norm_request.url or '', ignored_parameters) norm_request.headers = normalize_headers(norm_request.headers, ignored_parameters) norm_request.body = normalize_body(norm_request, ignored_parameters) return norm_request
def normalize_headers( headers: Mapping[str, str], ignored_parameters: ParamList ) -> CaseInsensitiveDict: """Sort and filter request headers""" if ignored_parameters: headers = filter_sort_dict(headers, ignored_parameters) return CaseInsensitiveDict(headers) def normalize_url(url: str, ignored_parameters: ParamList) -> str: """Normalize and filter a URL. This includes request parameters, IDN domains, scheme, host, port, etc. """ # Strip query params from URL, sort and filter, and reassemble into a complete URL url_tokens = urlparse(url) url = urlunparse( ( url_tokens.scheme, url_tokens.netloc, url_tokens.path, url_tokens.params, normalize_params(url_tokens.query, ignored_parameters), url_tokens.fragment, ) ) return url_normalize(url) def normalize_body(request: AnyPreparedRequest, ignored_parameters: ParamList) -> bytes: """Normalize and filter a request body if possible, depending on Content-Type""" original_body = request.body or b'' content_type = request.headers.get('Content-Type') # Filter and sort params if possible filtered_body: Union[str, bytes] = original_body if content_type == 'application/json': filtered_body = normalize_json_body(original_body, ignored_parameters) elif content_type == 'application/x-www-form-urlencoded': filtered_body = normalize_params(original_body, ignored_parameters) return encode(filtered_body) # TODO: Skip this for a very large response body? def normalize_json_body( original_body: Union[str, bytes], ignored_parameters: ParamList ) -> Union[str, bytes]: """Normalize and filter a request body with serialized JSON data""" try: body = json.loads(decode(original_body)) body = filter_sort_dict(body, ignored_parameters) return json.dumps(body) # If it's invalid JSON, then don't mess with it except (AttributeError, TypeError, ValueError): logger.debug('Invalid JSON body:', exc_info=True) return original_body def normalize_params(value: Union[str, bytes], ignored_parameters: ParamList) -> str: """Normalize and filter urlencoded params from either a URL or request body with form data""" query_str = decode(value) params = dict(parse_qsl(query_str)) # parse_qsl doesn't handle key-only params, so add those here key_only_params = [k for k in query_str.split('&') if k and '=' not in k] params.update({k: '' for k in key_only_params}) params = filter_sort_dict(params, ignored_parameters) return urlencode(params) def redact_response(response: CachedResponse, ignored_parameters: ParamList) -> CachedResponse: """Redact any ignored parameters (potentially containing sensitive info) from a cached request""" if ignored_parameters: response.url = normalize_url(response.url, ignored_parameters) response.request = normalize_request(response.request, ignored_parameters) # type: ignore return response def decode(value, encoding='utf-8') -> str: """Decode a value from bytes, if hasn't already been. Note: ``PreparedRequest.body`` is always encoded in utf-8. """ return value.decode(encoding) if isinstance(value, bytes) else value def encode(value, encoding='utf-8') -> bytes: """Encode a value to bytes, if it hasn't already been""" return value if isinstance(value, bytes) else str(value).encode(encoding) def filter_sort_dict(data: Mapping[str, str], ignored_parameters: ParamList) -> Dict[str, str]: if not ignored_parameters: return dict(sorted(data.items())) return {k: v for k, v in sorted(data.items()) if k not in set(ignored_parameters)}