from .._compat import string_types from .._internal import _get_environ from ..datastructures import ContentRange from ..datastructures import RequestCacheControl from ..datastructures import ResponseCacheControl from ..http import generate_etag from ..http import http_date from ..http import is_resource_modified from ..http import parse_cache_control_header from ..http import parse_content_range_header from ..http import parse_date from ..http import parse_etags from ..http import parse_if_range_header from ..http import parse_range_header from ..http import quote_etag from ..http import unquote_etag from ..utils import cached_property from ..utils import header_property from ..wrappers.base_response import _clean_accept_ranges from ..wsgi import _RangeWrapper class ETagRequestMixin(object): """Add entity tag and cache descriptors to a request object or object with a WSGI environment available as :attr:`~BaseRequest.environ`. This not only provides access to etags but also to the cache control header. """ @cached_property def cache_control(self): """A :class:`~werkzeug.datastructures.RequestCacheControl` object for the incoming cache control headers. """ cache_control = self.environ.get("HTTP_CACHE_CONTROL") return parse_cache_control_header(cache_control, None, RequestCacheControl) @cached_property def if_match(self): """An object containing all the etags in the `If-Match` header. :rtype: :class:`~werkzeug.datastructures.ETags` """ return parse_etags(self.environ.get("HTTP_IF_MATCH")) @cached_property def if_none_match(self): """An object containing all the etags in the `If-None-Match` header. :rtype: :class:`~werkzeug.datastructures.ETags` """ return parse_etags(self.environ.get("HTTP_IF_NONE_MATCH")) @cached_property def if_modified_since(self): """The parsed `If-Modified-Since` header as datetime object.""" return parse_date(self.environ.get("HTTP_IF_MODIFIED_SINCE")) @cached_property def if_unmodified_since(self): """The parsed `If-Unmodified-Since` header as datetime object.""" return parse_date(self.environ.get("HTTP_IF_UNMODIFIED_SINCE")) @cached_property def if_range(self): """The parsed `If-Range` header. .. versionadded:: 0.7 :rtype: :class:`~werkzeug.datastructures.IfRange` """ return parse_if_range_header(self.environ.get("HTTP_IF_RANGE")) @cached_property def range(self): """The parsed `Range` header. .. versionadded:: 0.7 :rtype: :class:`~werkzeug.datastructures.Range` """ return parse_range_header(self.environ.get("HTTP_RANGE")) class ETagResponseMixin(object): """Adds extra functionality to a response object for etag and cache handling. This mixin requires an object with at least a `headers` object that implements a dict like interface similar to :class:`~werkzeug.datastructures.Headers`. If you want the :meth:`freeze` method to automatically add an etag, you have to mixin this method before the response base class. The default response class does not do that. """ @property def cache_control(self): """The Cache-Control general-header field is used to specify directives that MUST be obeyed by all caching mechanisms along the request/response chain. """ def on_update(cache_control): if not cache_control and "cache-control" in self.headers: del self.headers["cache-control"] elif cache_control: self.headers["Cache-Control"] = cache_control.to_header() return parse_cache_control_header( self.headers.get("cache-control"), on_update, ResponseCacheControl ) def _wrap_response(self, start, length): """Wrap existing Response in case of Range Request context.""" if self.status_code == 206: self.response = _RangeWrapper(self.response, start, length) def _is_range_request_processable(self, environ): """Return ``True`` if `Range` header is present and if underlying resource is considered unchanged when compared with `If-Range` header. """ return ( "HTTP_IF_RANGE" not in environ or not is_resource_modified( environ, self.headers.get("etag"), None, self.headers.get("last-modified"), ignore_if_range=False, ) ) and "HTTP_RANGE" in environ def _process_range_request(self, environ, complete_length=None, accept_ranges=None): """Handle Range Request related headers (RFC7233). If `Accept-Ranges` header is valid, and Range Request is processable, we set the headers as described by the RFC, and wrap the underlying response in a RangeWrapper. Returns ``True`` if Range Request can be fulfilled, ``False`` otherwise. :raises: :class:`~werkzeug.exceptions.RequestedRangeNotSatisfiable` if `Range` header could not be parsed or satisfied. """ from ..exceptions import RequestedRangeNotSatisfiable if ( accept_ranges is None or complete_length is None or not self._is_range_request_processable(environ) ): return False parsed_range = parse_range_header(environ.get("HTTP_RANGE")) if parsed_range is None: raise RequestedRangeNotSatisfiable(complete_length) range_tuple = parsed_range.range_for_length(complete_length) content_range_header = parsed_range.to_content_range_header(complete_length) if range_tuple is None or content_range_header is None: raise RequestedRangeNotSatisfiable(complete_length) content_length = range_tuple[1] - range_tuple[0] self.headers["Content-Length"] = content_length self.headers["Accept-Ranges"] = accept_ranges self.content_range = content_range_header self.status_code = 206 self._wrap_response(range_tuple[0], content_length) return True def make_conditional( self, request_or_environ, accept_ranges=False, complete_length=None ): """Make the response conditional to the request. This method works best if an etag was defined for the response already. The `add_etag` method can be used to do that. If called without etag just the date header is set. This does nothing if the request method in the request or environ is anything but GET or HEAD. For optimal performance when handling range requests, it's recommended that your response data object implements `seekable`, `seek` and `tell` methods as described by :py:class:`io.IOBase`. Objects returned by :meth:`~werkzeug.wsgi.wrap_file` automatically implement those methods. It does not remove the body of the response because that's something the :meth:`__call__` function does for us automatically. Returns self so that you can do ``return resp.make_conditional(req)`` but modifies the object in-place. :param request_or_environ: a request object or WSGI environment to be used to make the response conditional against. :param accept_ranges: This parameter dictates the value of `Accept-Ranges` header. If ``False`` (default), the header is not set. If ``True``, it will be set to ``"bytes"``. If ``None``, it will be set to ``"none"``. If it's a string, it will use this value. :param complete_length: Will be used only in valid Range Requests. It will set `Content-Range` complete length value and compute `Content-Length` real value. This parameter is mandatory for successful Range Requests completion. :raises: :class:`~werkzeug.exceptions.RequestedRangeNotSatisfiable` if `Range` header could not be parsed or satisfied. """ environ = _get_environ(request_or_environ) if environ["REQUEST_METHOD"] in ("GET", "HEAD"): # if the date is not in the headers, add it now. We however # will not override an already existing header. Unfortunately # this header will be overriden by many WSGI servers including # wsgiref. if "date" not in self.headers: self.headers["Date"] = http_date() accept_ranges = _clean_accept_ranges(accept_ranges) is206 = self._process_range_request(environ, complete_length, accept_ranges) if not is206 and not is_resource_modified( environ, self.headers.get("etag"), None, self.headers.get("last-modified"), ): if parse_etags(environ.get("HTTP_IF_MATCH")): self.status_code = 412 else: self.status_code = 304 if ( self.automatically_set_content_length and "content-length" not in self.headers ): length = self.calculate_content_length() if length is not None: self.headers["Content-Length"] = length return self def add_etag(self, overwrite=False, weak=False): """Add an etag for the current response if there is none yet.""" if overwrite or "etag" not in self.headers: self.set_etag(generate_etag(self.get_data()), weak) def set_etag(self, etag, weak=False): """Set the etag, and override the old one if there was one.""" self.headers["ETag"] = quote_etag(etag, weak) def get_etag(self): """Return a tuple in the form ``(etag, is_weak)``. If there is no ETag the return value is ``(None, None)``. """ return unquote_etag(self.headers.get("ETag")) def freeze(self, no_etag=False): """Call this method if you want to make your response object ready for pickeling. This buffers the generator if there is one. This also sets the etag unless `no_etag` is set to `True`. """ if not no_etag: self.add_etag() super(ETagResponseMixin, self).freeze() accept_ranges = header_property( "Accept-Ranges", doc="""The `Accept-Ranges` header. Even though the name would indicate that multiple values are supported, it must be one string token only. The values ``'bytes'`` and ``'none'`` are common. .. versionadded:: 0.7""", ) @property def content_range(self): """The ``Content-Range`` header as a :class:`~werkzeug.datastructures.ContentRange` object. Available even if the header is not set. .. versionadded:: 0.7 """ def on_update(rng): if not rng: del self.headers["content-range"] else: self.headers["Content-Range"] = rng.to_header() rv = parse_content_range_header(self.headers.get("content-range"), on_update) # always provide a content range object to make the descriptor # more user friendly. It provides an unset() method that can be # used to remove the header quickly. if rv is None: rv = ContentRange(None, None, None, on_update=on_update) return rv @content_range.setter def content_range(self, value): if not value: del self.headers["content-range"] elif isinstance(value, string_types): self.headers["Content-Range"] = value else: self.headers["Content-Range"] = value.to_header()