# Copyright 2013 by Rackspace Hosting, Inc.
#
# Licensed 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.
from six import PY2
from six import string_types as STRING_TYPES
# NOTE(tbug): In some cases, http_cookies is not a module
# but a dict-like structure. This fixes that issue.
# See issue https://github.com/falconry/falcon/issues/556
from six.moves import http_cookies
from falcon.response_helpers import header_property, format_range
from falcon.response_helpers import is_ascii_encodable
from falcon.util import dt_to_http, TimezoneGMT
from falcon.util.uri import encode as uri_encode
from falcon.util.uri import encode_value as uri_encode_value
SimpleCookie = http_cookies.SimpleCookie
CookieError = http_cookies.CookieError
GMT_TIMEZONE = TimezoneGMT()
[docs]class Response(object):
"""Represents an HTTP response to a client request.
Note:
`Response` is not meant to be instantiated directly by responders.
Attributes:
status (str): HTTP status line (e.g., '200 OK'). Falcon requires the
full status line, not just the code (e.g., 200). This design
makes the framework more efficient because it does not have to
do any kind of conversion or lookup when composing the WSGI
response.
If not set explicitly, the status defaults to '200 OK'.
Note:
Falcon provides a number of constants for common status
codes. They all start with the ``HTTP_`` prefix, as in:
``falcon.HTTP_204``.
body (str or unicode): String representing response content. If
Unicode, Falcon will encode as UTF-8 in the response. If
data is already a byte string, use the data attribute
instead (it's faster).
data (bytes): Byte string representing response content.
Use this attribute in lieu of `body` when your content is
already a byte string (``str`` or ``bytes`` in Python 2, or
simply ``bytes`` in Python 3). See also the note below.
Note:
Under Python 2.x, if your content is of type ``str``, using
the `data` attribute instead of `body` is the most
efficient approach. However, if
your text is of type ``unicode``, you will need to use the
`body` attribute instead.
Under Python 3.x, on the other hand, the 2.x ``str`` type can
be thought of as
having been replaced by what was once the ``unicode`` type,
and so you will need to always use the `body` attribute for
strings to
ensure Unicode characters are properly encoded in the
HTTP response.
stream: Either a file-like object with a `read()` method that takes
an optional size argument and returns a block of bytes, or an
iterable object, representing response content, and yielding
blocks as byte strings. Falcon will use *wsgi.file_wrapper*, if
provided by the WSGI server, in order to efficiently serve
file-like objects.
stream_len (int): Expected length of `stream`. If `stream` is set,
but `stream_len` is not, Falcon will not supply a
Content-Length header to the WSGI server. Consequently, the
server may choose to use chunked encoding or one of the
other strategies suggested by PEP-3333.
"""
__slots__ = (
'body',
'data',
'_headers',
'_cookies',
'status',
'stream',
'stream_len'
)
def __init__(self):
self.status = '200 OK'
self._headers = {}
# NOTE(tbug): will be set to a SimpleCookie object
# when cookie is set via set_cookie
self._cookies = None
self.body = None
self.data = None
self.stream = None
self.stream_len = None
[docs] def set_stream(self, stream, stream_len):
"""Convenience method for setting both `stream` and `stream_len`.
Although the `stream` and `stream_len` properties may be set
directly, using this method ensures `stream_len` is not
accidentally neglected when the length of the stream is known in
advance.
Note:
If the stream length is unknown, you can set `stream`
directly, and ignore `stream_len`. In this case, the
WSGI server may choose to use chunked encoding or one
of the other strategies suggested by PEP-3333.
"""
self.stream = stream
self.stream_len = stream_len
[docs] def set_cookie(self, name, value, expires=None, max_age=None,
domain=None, path=None, secure=True, http_only=True):
"""Set a response cookie.
Note:
This method can be called multiple times to add one or
more cookies to the response.
See Also:
To learn more about setting cookies, see
:ref:`Setting Cookies <setting-cookies>`. The parameters listed
below correspond to those defined in `RFC 6265`_.
Args:
name (str):
Cookie name
value (str):
Cookie value
expires (datetime): Specifies when the cookie should expire. By
default, cookies expire when the user agent exits.
max_age (int): Defines the lifetime of the cookie in seconds.
After the specified number of seconds elapse, the client
should discard the cookie. Coercion to `int` is attempted
if provided with `float` or `str`.
domain (str): Specifies the domain for which the cookie is valid.
An explicitly specified domain must always start with a dot.
A value of 0 means the cookie should be discarded immediately.
path (str): Specifies the subset of URLs to
which this cookie applies.
secure (bool): Direct the client to only return the cookie in
subsequent requests if they are made over HTTPS
(default: ``True``). This prevents attackers from reading
sensitive cookie data. Note that for the `secure` cookie
attribute to be effective, your application will need to
enforce HTTPS. See also: `RFC 6265, Section 4.1.2.5`_.
http_only (bool): Direct the client to only transfer the cookie
with unscripted HTTP requests (default: ``True``). This is
intended to mitigate some forms of cross-site scripting.
Raises:
KeyError: `name` is not a valid cookie name.
ValueError: `value` is not a valid cookie value.
.. _RFC 6265:
http://tools.ietf.org/html/rfc6265
.. _RFC 6265, Section 4.1.2.5:
https://tools.ietf.org/html/rfc6265#section-4.1.2.5
"""
if not is_ascii_encodable(name):
raise KeyError('"name" is not ascii encodable')
if not is_ascii_encodable(value):
raise ValueError('"value" is not ascii encodable')
if PY2:
name = str(name)
value = str(value)
if self._cookies is None:
self._cookies = SimpleCookie()
try:
self._cookies[name] = value
except CookieError as e: # pragma: no cover
# NOTE(tbug): we raise a KeyError here, to avoid leaking
# the CookieError to the user. SimpleCookie (well, BaseCookie)
# only throws CookieError on issues with the cookie key
raise KeyError(str(e))
if expires:
# set Expires on cookie. Format is Wdy, DD Mon YYYY HH:MM:SS GMT
# NOTE(tbug): we never actually need to
# know that GMT is named GMT when formatting cookies.
# It is a function call less to just write "GMT" in the fmt string:
fmt = '%a, %d %b %Y %H:%M:%S GMT'
if expires.tzinfo is None:
# naive
self._cookies[name]['expires'] = expires.strftime(fmt)
else:
# aware
gmt_expires = expires.astimezone(GMT_TIMEZONE)
self._cookies[name]['expires'] = gmt_expires.strftime(fmt)
if max_age:
# RFC 6265 section 5.2.2 says about the max-age value:
# "If the remainder of attribute-value contains a non-DIGIT
# character, ignore the cookie-av."
# That is, RFC-compliant response parsers will ignore the max-age
# attribute if the value contains a dot, as in floating point
# numbers. Therefore, attempt to convert the value to an integer.
self._cookies[name]['max-age'] = int(max_age)
if domain:
self._cookies[name]['domain'] = domain
if path:
self._cookies[name]['path'] = path
if secure:
self._cookies[name]['secure'] = secure
if http_only:
self._cookies[name]['httponly'] = http_only
[docs] def unset_cookie(self, name):
"""Unset a cookie in the response
Note:
This will clear the contents of the cookie, and instruct
the browser to immediately expire its own copy of the
cookie, if any.
"""
if self._cookies is None:
self._cookies = SimpleCookie()
self._cookies[name] = ''
# NOTE(Freezerburn): SimpleCookie apparently special cases the
# expires attribute to automatically use strftime and set the
# time as a delta from the current time. We use -1 here to
# basically tell the browser to immediately expire the cookie,
# thus removing it from future request objects.
self._cookies[name]['expires'] = -1
[docs] def add_link(self, target, rel, title=None, title_star=None,
anchor=None, hreflang=None, type_hint=None):
"""
Add a link header to the response.
See also: https://tools.ietf.org/html/rfc5988
Note:
Calling this method repeatedly will cause each link to be
appended to the Link header value, separated by commas.
Note:
So-called "link-extension" elements, as defined by RFC 5988,
are not yet supported. See also Issue #288.
Args:
target (str): Target IRI for the resource identified by the
link. Will be converted to a URI, if necessary, per
RFC 3987, Section 3.1.
rel (str): Relation type of the link, such as "next" or
"bookmark". See also http://goo.gl/618GHr for a list
of registered link relation types.
Kwargs:
title (str): Human-readable label for the destination of
the link (default ``None``). If the title includes non-ASCII
characters, you will need to use `title_star` instead, or
provide both a US-ASCII version using `title` and a
Unicode version using `title_star`.
title_star (tuple of str): Localized title describing the
destination of the link (default ``None``). The value must be a
two-member tuple in the form of (*language-tag*, *text*),
where *language-tag* is a standard language identifier as
defined in RFC 5646, Section 2.1, and *text* is a Unicode
string.
Note:
*language-tag* may be an empty string, in which case the
client will assume the language from the general context
of the current request.
Note:
*text* will always be encoded as UTF-8. If the string
contains non-ASCII characters, it should be passed as
a ``unicode`` type string (requires the 'u' prefix in
Python 2).
anchor (str): Override the context IRI with a different URI
(default None). By default, the context IRI for the link is
simply the IRI of the requested resource. The value
provided may be a relative URI.
hreflang (str or iterable): Either a single *language-tag*, or
a ``list`` or ``tuple`` of such tags to provide a hint to the
client as to the language of the result of following the link.
A list of tags may be given in order to indicate to the
client that the target resource is available in multiple
languages.
type_hint(str): Provides a hint as to the media type of the
result of dereferencing the link (default ``None``). As noted
in RFC 5988, this is only a hint and does not override the
Content-Type header returned when the link is followed.
"""
# PERF(kgriffs): Heuristic to detect possiblity of an extension
# relation type, in which case it will be a URL that may contain
# reserved characters. Otherwise, don't waste time running the
# string through uri.encode
#
# Example values for rel:
#
# "next"
# "http://example.com/ext-type"
# "https://example.com/ext-type"
# "alternate http://example.com/ext-type"
# "http://example.com/ext-type alternate"
#
if '//' in rel:
if ' ' in rel:
rel = ('"' +
' '.join([uri_encode(r) for r in rel.split()]) +
'"')
else:
rel = '"' + uri_encode(rel) + '"'
value = '<' + uri_encode(target) + '>; rel=' + rel
if title is not None:
value += '; title="' + title + '"'
if title_star is not None:
value += ("; title*=UTF-8'" + title_star[0] + "'" +
uri_encode_value(title_star[1]))
if type_hint is not None:
value += '; type="' + type_hint + '"'
if hreflang is not None:
if isinstance(hreflang, STRING_TYPES):
value += '; hreflang=' + hreflang
else:
value += '; '
value += '; '.join(['hreflang=' + lang for lang in hreflang])
if anchor is not None:
value += '; anchor="' + uri_encode(anchor) + '"'
_headers = self._headers
if 'link' in _headers:
_headers['link'] += ', ' + value
else:
_headers['link'] = value
cache_control = header_property(
'Cache-Control',
"""Sets the Cache-Control header.
Used to set a list of cache directives to use as the value of the
Cache-Control header. The list will be joined with ", " to produce
the value for the header.
""",
lambda v: ', '.join(v))
content_location = header_property(
'Content-Location',
'Sets the Content-Location header.',
uri_encode)
content_range = header_property(
'Content-Range',
"""A tuple to use in constructing a value for the Content-Range header.
The tuple has the form (*start*, *end*, *length*, [*unit*]), where *start* and
*end* designate the range (inclusive), and *length* is the
total length, or '\*' if unknown. You may pass ``int``'s for
these numbers (no need to convert to ``str`` beforehand). The optional value
*unit* describes the range unit and defaults to 'bytes'
Note:
You only need to use the alternate form, 'bytes \*/1234', for
responses that use the status '416 Range Not Satisfiable'. In this
case, raising ``falcon.HTTPRangeNotSatisfiable`` will do the right
thing.
See also: http://goo.gl/Iglhp
""",
format_range)
content_type = header_property(
'Content-Type',
'Sets the Content-Type header.')
etag = header_property(
'ETag',
'Sets the ETag header.')
last_modified = header_property(
'Last-Modified',
"""Sets the Last-Modified header. Set to a ``datetime`` (UTC) instance.
Note:
Falcon will format the ``datetime`` as an HTTP date string.
""",
dt_to_http)
location = header_property(
'Location',
'Sets the Location header.',
uri_encode)
retry_after = header_property(
'Retry-After',
"""Sets the Retry-After header.
The expected value is an integral number of seconds to use as the
value for the header. The HTTP-date syntax is not supported.
""",
str)
vary = header_property(
'Vary',
"""Value to use for the Vary header.
Set this property to an iterable of header names. For a single
asterisk or field value, simply pass a single-element ``list`` or
``tuple``.
"Tells downstream proxies how to match future request headers
to decide whether the cached response can be used rather than
requesting a fresh one from the origin server."
(Wikipedia)
See also: http://goo.gl/NGHdL
""",
lambda v: ', '.join(v))
def _encode_header(self, name, value, py2=PY2):
if py2:
if isinstance(name, unicode):
name = name.encode('ISO-8859-1')
if isinstance(value, unicode):
value = value.encode('ISO-8859-1')
return name, value
def _wsgi_headers(self, media_type=None, py2=PY2):
"""Convert headers into the format expected by WSGI servers.
Args:
media_type: Default media type to use for the Content-Type
header if the header was not set explicitly (default ``None``).
"""
headers = self._headers
# PERF(kgriffs): Using "in" like this is faster than using
# dict.setdefault (tested on py27).
set_content_type = (media_type is not None and
'content-type' not in headers)
if set_content_type:
headers['content-type'] = media_type
if py2:
# PERF(kgriffs): Don't create an extra list object if
# it isn't needed.
items = headers.items()
else:
items = list(headers.items())
if self._cookies is not None:
# PERF(tbug):
# The below implementation is ~23% faster than
# the alternative:
#
# self._cookies.output().split("\\r\\n")
#
# Even without the .split("\\r\\n"), the below
# is still ~17% faster, so don't use .output()
items += [('set-cookie', c.OutputString())
for c in self._cookies.values()]
return items