Source code for werkzeug.http

# -*- coding: utf-8 -*-

    Werkzeug comes with a bunch of utilities that help Werkzeug to deal with
    HTTP data.  Most of the classes and functions provided by this module are
    used by the wrappers, but they are useful on their own, too, especially if
    the response and request objects are not used.

    This covers some of the more HTTP centric features of WSGI, some other
    utilities such as cookie handling are documented in the `werkzeug.utils`

    :copyright: (c) 2014 by the Werkzeug Team, see AUTHORS for more details.
    :license: BSD, see LICENSE for more details.
import re
from time import time, gmtime
    from email.utils import parsedate_tz
except ImportError:  # pragma: no cover
    from email.Utils import parsedate_tz
    from urllib2 import parse_http_list as _parse_list_header
except ImportError:  # pragma: no cover
    from urllib.request import parse_http_list as _parse_list_header
from datetime import datetime, timedelta
from hashlib import md5
import base64

from werkzeug._internal import _cookie_quote, _make_cookie_domain, \
from werkzeug._compat import to_unicode, iteritems, text_type, \
    string_types, try_coerce_native, to_bytes, PY2, \

_cookie_charset = 'latin1'
# for explanation of "media-range", etc. see Sections 5.3.{1,2} of RFC 7231
_accept_re = re.compile(
    r'''(                       # media-range capturing-parenthesis
              [^\s;,]+              # type/subtype
              (?:[ \t]*;[ \t]*      # ";"
                (?:                 # parameter non-capturing-parenthesis
                  [^\s;,q][^\s;,]*  # token that doesn't start with "q"
                |                   # or
                  q[^\s;,=][^\s;,]* # token that is more than just "q"
              )*                    # zero or more parameters
            )                       # end of media-range
            (?:[ \t]*;[ \t]*q=      # weight is a "q" parameter
              (\d*(?:\.\d+)?)       # qvalue capturing-parentheses
              [^,]*                 # "extension" accept params: who cares?
            )?                      # accept params are optional
        ''', re.VERBOSE)
_token_chars = frozenset("!#$%&'*+-.0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
_etag_re = re.compile(r'([Ww]/)?(?:"(.*?)"|(.*?))(?:\s*,\s*|$)')
_unsafe_header_chars = set('()<>@,;:\"/[]?={} \t')
_quoted_string_re = r'"[^"\\]*(?:\\.[^"\\]*)*"'
_option_header_piece_re = re.compile(
    r';\s*(%s|[^\s;,=]+)\s*(?:=\s*(%s|[^;,]+)?)?\s*' %
    (_quoted_string_re, _quoted_string_re)
_option_header_start_mime_type = re.compile(r',\s*([^;,\s]+)([;,]\s*.+)?')

_entity_headers = frozenset([
    'allow', 'content-encoding', 'content-language', 'content-length',
    'content-location', 'content-md5', 'content-range', 'content-type',
    'expires', 'last-modified'
_hop_by_hop_headers = frozenset([
    'connection', 'keep-alive', 'proxy-authenticate',
    'proxy-authorization', 'te', 'trailer', 'transfer-encoding',

    100:    'Continue',
    101:    'Switching Protocols',
    102:    'Processing',
    200:    'OK',
    201:    'Created',
    202:    'Accepted',
    203:    'Non Authoritative Information',
    204:    'No Content',
    205:    'Reset Content',
    206:    'Partial Content',
    207:    'Multi Status',
    226:    'IM Used',              # see RFC 3229
    300:    'Multiple Choices',
    301:    'Moved Permanently',
    302:    'Found',
    303:    'See Other',
    304:    'Not Modified',
    305:    'Use Proxy',
    307:    'Temporary Redirect',
    400:    'Bad Request',
    401:    'Unauthorized',
    402:    'Payment Required',     # unused
    403:    'Forbidden',
    404:    'Not Found',
    405:    'Method Not Allowed',
    406:    'Not Acceptable',
    407:    'Proxy Authentication Required',
    408:    'Request Timeout',
    409:    'Conflict',
    410:    'Gone',
    411:    'Length Required',
    412:    'Precondition Failed',
    413:    'Request Entity Too Large',
    414:    'Request URI Too Long',
    415:    'Unsupported Media Type',
    416:    'Requested Range Not Satisfiable',
    417:    'Expectation Failed',
    418:    'I\'m a teapot',  # see RFC 2324
    422:    'Unprocessable Entity',
    423:    'Locked',
    424:    'Failed Dependency',
    426:    'Upgrade Required',
    428:    'Precondition Required',  # see RFC 6585
    429:    'Too Many Requests',
    431:    'Request Header Fields Too Large',
    449:    'Retry With',  # proprietary MS extension
    500:    'Internal Server Error',
    501:    'Not Implemented',
    502:    'Bad Gateway',
    503:    'Service Unavailable',
    504:    'Gateway Timeout',
    505:    'HTTP Version Not Supported',
    507:    'Insufficient Storage',
    510:    'Not Extended'

def wsgi_to_bytes(data):
    """coerce wsgi unicode represented bytes to real ones

    if isinstance(data, bytes):
        return data
    return data.encode('latin1')  # XXX: utf8 fallback?

def bytes_to_wsgi(data):
    assert isinstance(data, bytes), 'data must be bytes'
    if isinstance(data, str):
        return data
        return data.decode('latin1')

[docs]def quote_header_value(value, extra_chars='', allow_token=True): """Quote a header value if necessary. .. versionadded:: 0.5 :param value: the value to quote. :param extra_chars: a list of extra characters to skip quoting. :param allow_token: if this is enabled token values are returned unchanged. """ if isinstance(value, bytes): value = bytes_to_wsgi(value) value = str(value) if allow_token: token_chars = _token_chars | set(extra_chars) if set(value).issubset(token_chars): return value return '"%s"' % value.replace('\\', '\\\\').replace('"', '\\"')
[docs]def unquote_header_value(value, is_filename=False): r"""Unquotes a header value. (Reversal of :func:`quote_header_value`). This does not use the real unquoting but what browsers are actually using for quoting. .. versionadded:: 0.5 :param value: the header value to unquote. """ if value and value[0] == value[-1] == '"': # this is not the real unquoting, but fixing this so that the # RFC is met will result in bugs with internet explorer and # probably some other browsers as well. IE for example is # uploading files with "C:\foo\bar.txt" as filename value = value[1:-1] # if this is a filename and the starting characters look like # a UNC path, then just return the value without quotes. Using the # replace sequence below on a UNC path has the effect of turning # the leading double slash into a single slash and then # _fix_ie_filename() doesn't work correctly. See #458. if not is_filename or value[:2] != '\\\\': return value.replace('\\\\', '\\').replace('\\"', '"') return value
[docs]def dump_options_header(header, options): """The reverse function to :func:`parse_options_header`. :param header: the header to dump :param options: a dict of options to append. """ segments = [] if header is not None: segments.append(header) for key, value in iteritems(options): if value is None: segments.append(key) else: segments.append('%s=%s' % (key, quote_header_value(value))) return '; '.join(segments)
[docs]def dump_header(iterable, allow_token=True): """Dump an HTTP header again. This is the reversal of :func:`parse_list_header`, :func:`parse_set_header` and :func:`parse_dict_header`. This also quotes strings that include an equals sign unless you pass it as dict of key, value pairs. >>> dump_header({'foo': 'bar baz'}) 'foo="bar baz"' >>> dump_header(('foo', 'bar baz')) 'foo, "bar baz"' :param iterable: the iterable or dict of values to quote. :param allow_token: if set to `False` tokens as values are disallowed. See :func:`quote_header_value` for more details. """ if isinstance(iterable, dict): items = [] for key, value in iteritems(iterable): if value is None: items.append(key) else: items.append('%s=%s' % ( key, quote_header_value(value, allow_token=allow_token) )) else: items = [quote_header_value(x, allow_token=allow_token) for x in iterable] return ', '.join(items)
[docs]def parse_list_header(value): """Parse lists as described by RFC 2068 Section 2. In particular, parse comma-separated lists where the elements of the list may include quoted-strings. A quoted-string could contain a comma. A non-quoted string could have quotes in the middle. Quotes are removed automatically after parsing. It basically works like :func:`parse_set_header` just that items may appear multiple times and case sensitivity is preserved. The return value is a standard :class:`list`: >>> parse_list_header('token, "quoted value"') ['token', 'quoted value'] To create a header from the :class:`list` again, use the :func:`dump_header` function. :param value: a string with a list header. :return: :class:`list` """ result = [] for item in _parse_list_header(value): if item[:1] == item[-1:] == '"': item = unquote_header_value(item[1:-1]) result.append(item) return result
[docs]def parse_dict_header(value, cls=dict): """Parse lists of key, value pairs as described by RFC 2068 Section 2 and convert them into a python dict (or any other mapping object created from the type with a dict like interface provided by the `cls` arugment): >>> d = parse_dict_header('foo="is a fish", bar="as well"') >>> type(d) is dict True >>> sorted(d.items()) [('bar', 'as well'), ('foo', 'is a fish')] If there is no value for a key it will be `None`: >>> parse_dict_header('key_without_value') {'key_without_value': None} To create a header from the :class:`dict` again, use the :func:`dump_header` function. .. versionchanged:: 0.9 Added support for `cls` argument. :param value: a string with a dict header. :param cls: callable to use for storage of parsed results. :return: an instance of `cls` """ result = cls() if not isinstance(value, text_type): # XXX: validate value = bytes_to_wsgi(value) for item in _parse_list_header(value): if '=' not in item: result[item] = None continue name, value = item.split('=', 1) if value[:1] == value[-1:] == '"': value = unquote_header_value(value[1:-1]) result[name] = value return result
[docs]def parse_options_header(value, multiple=False): """Parse a ``Content-Type`` like header into a tuple with the content type and the options: >>> parse_options_header('text/html; charset=utf8') ('text/html', {'charset': 'utf8'}) This should not be used to parse ``Cache-Control`` like headers that use a slightly different format. For these headers use the :func:`parse_dict_header` function. .. versionadded:: 0.5 :param value: the header to parse. :param multiple: Whether try to parse and return multiple MIME types :return: (mimetype, options) or (mimetype, options, mimetype, options, …) if multiple=True """ if not value: return '', {} result = [] value = "," + value.replace("\n", ",") while value: match = _option_header_start_mime_type.match(value) if not match: break result.append( # mimetype options = {} # Parse options rest = while rest: optmatch = _option_header_piece_re.match(rest) if not optmatch: break option, option_value = optmatch.groups() option = unquote_header_value(option) if option_value is not None: option_value = unquote_header_value( option_value, option == 'filename') options[option] = option_value rest = rest[optmatch.end():] result.append(options) if multiple is False: return tuple(result) value = rest return tuple(result) if result else ('', {})
[docs]def parse_accept_header(value, cls=None): """Parses an HTTP Accept-* header. This does not implement a complete valid algorithm but one that supports at least value and quality extraction. Returns a new :class:`Accept` object (basically a list of ``(value, quality)`` tuples sorted by the quality with some additional accessor methods). The second parameter can be a subclass of :class:`Accept` that is created with the parsed values and returned. :param value: the accept header string to be parsed. :param cls: the wrapper class for the return value (can be :class:`Accept` or a subclass thereof) :return: an instance of `cls`. """ if cls is None: cls = Accept if not value: return cls(None) result = [] for match in _accept_re.finditer(value): quality = if not quality: quality = 1 else: quality = max(min(float(quality), 1), 0) result.append((, quality)) return cls(result)
[docs]def parse_cache_control_header(value, on_update=None, cls=None): """Parse a cache control header. The RFC differs between response and request cache control, this method does not. It's your responsibility to not use the wrong control statements. .. versionadded:: 0.5 The `cls` was added. If not specified an immutable :class:`~werkzeug.datastructures.RequestCacheControl` is returned. :param value: a cache control header to be parsed. :param on_update: an optional callable that is called every time a value on the :class:`~werkzeug.datastructures.CacheControl` object is changed. :param cls: the class for the returned object. By default :class:`~werkzeug.datastructures.RequestCacheControl` is used. :return: a `cls` object. """ if cls is None: cls = RequestCacheControl if not value: return cls(None, on_update) return cls(parse_dict_header(value), on_update)
[docs]def parse_set_header(value, on_update=None): """Parse a set-like header and return a :class:`~werkzeug.datastructures.HeaderSet` object: >>> hs = parse_set_header('token, "quoted value"') The return value is an object that treats the items case-insensitively and keeps the order of the items: >>> 'TOKEN' in hs True >>> hs.index('quoted value') 1 >>> hs HeaderSet(['token', 'quoted value']) To create a header from the :class:`HeaderSet` again, use the :func:`dump_header` function. :param value: a set header to be parsed. :param on_update: an optional callable that is called every time a value on the :class:`~werkzeug.datastructures.HeaderSet` object is changed. :return: a :class:`~werkzeug.datastructures.HeaderSet` """ if not value: return HeaderSet(None, on_update) return HeaderSet(parse_list_header(value), on_update)
[docs]def parse_authorization_header(value): """Parse an HTTP basic/digest authorization header transmitted by the web browser. The return value is either `None` if the header was invalid or not given, otherwise an :class:`~werkzeug.datastructures.Authorization` object. :param value: the authorization header to parse. :return: a :class:`~werkzeug.datastructures.Authorization` object or `None`. """ if not value: return value = wsgi_to_bytes(value) try: auth_type, auth_info = value.split(None, 1) auth_type = auth_type.lower() except ValueError: return if auth_type == b'basic': try: username, password = base64.b64decode(auth_info).split(b':', 1) except Exception: return return Authorization('basic', {'username': bytes_to_wsgi(username), 'password': bytes_to_wsgi(password)}) elif auth_type == b'digest': auth_map = parse_dict_header(auth_info) for key in 'username', 'realm', 'nonce', 'uri', 'response': if key not in auth_map: return if 'qop' in auth_map: if not auth_map.get('nc') or not auth_map.get('cnonce'): return return Authorization('digest', auth_map)
[docs]def parse_www_authenticate_header(value, on_update=None): """Parse an HTTP WWW-Authenticate header into a :class:`~werkzeug.datastructures.WWWAuthenticate` object. :param value: a WWW-Authenticate header to parse. :param on_update: an optional callable that is called every time a value on the :class:`~werkzeug.datastructures.WWWAuthenticate` object is changed. :return: a :class:`~werkzeug.datastructures.WWWAuthenticate` object. """ if not value: return WWWAuthenticate(on_update=on_update) try: auth_type, auth_info = value.split(None, 1) auth_type = auth_type.lower() except (ValueError, AttributeError): return WWWAuthenticate(value.strip().lower(), on_update=on_update) return WWWAuthenticate(auth_type, parse_dict_header(auth_info), on_update)
def parse_if_range_header(value): """Parses an if-range header which can be an etag or a date. Returns a :class:`~werkzeug.datastructures.IfRange` object. .. versionadded:: 0.7 """ if not value: return IfRange() date = parse_date(value) if date is not None: return IfRange(date=date) # drop weakness information return IfRange(unquote_etag(value)[0]) def parse_range_header(value, make_inclusive=True): """Parses a range header into a :class:`~werkzeug.datastructures.Range` object. If the header is missing or malformed `None` is returned. `ranges` is a list of ``(start, stop)`` tuples where the ranges are non-inclusive. .. versionadded:: 0.7 """ if not value or '=' not in value: return None ranges = [] last_end = 0 units, rng = value.split('=', 1) units = units.strip().lower() for item in rng.split(','): item = item.strip() if '-' not in item: return None if item.startswith('-'): if last_end < 0: return None begin = int(item) end = None last_end = -1 elif '-' in item: begin, end = item.split('-', 1) begin = int(begin) if begin < last_end or last_end < 0: return None if end: end = int(end) + 1 if begin >= end: return None else: end = None last_end = end ranges.append((begin, end)) return Range(units, ranges) def parse_content_range_header(value, on_update=None): """Parses a range header into a :class:`~werkzeug.datastructures.ContentRange` object or `None` if parsing is not possible. .. versionadded:: 0.7 :param value: a content range header to be parsed. :param on_update: an optional callable that is called every time a value on the :class:`~werkzeug.datastructures.ContentRange` object is changed. """ if value is None: return None try: units, rangedef = (value or '').strip().split(None, 1) except ValueError: return None if '/' not in rangedef: return None rng, length = rangedef.split('/', 1) if length == '*': length = None elif length.isdigit(): length = int(length) else: return None if rng == '*': return ContentRange(units, None, None, length, on_update=on_update) elif '-' not in rng: return None start, stop = rng.split('-', 1) try: start = int(start) stop = int(stop) + 1 except ValueError: return None if is_byte_range_valid(start, stop, length): return ContentRange(units, start, stop, length, on_update=on_update)
[docs]def quote_etag(etag, weak=False): """Quote an etag. :param etag: the etag to quote. :param weak: set to `True` to tag it "weak". """ if '"' in etag: raise ValueError('invalid etag') etag = '"%s"' % etag if weak: etag = 'W/' + etag return etag
[docs]def unquote_etag(etag): """Unquote a single etag: >>> unquote_etag('W/"bar"') ('bar', True) >>> unquote_etag('"bar"') ('bar', False) :param etag: the etag identifier to unquote. :return: a ``(etag, weak)`` tuple. """ if not etag: return None, None etag = etag.strip() weak = False if etag.startswith(('W/', 'w/')): weak = True etag = etag[2:] if etag[:1] == etag[-1:] == '"': etag = etag[1:-1] return etag, weak
[docs]def parse_etags(value): """Parse an etag header. :param value: the tag header to parse :return: an :class:`~werkzeug.datastructures.ETags` object. """ if not value: return ETags() strong = [] weak = [] end = len(value) pos = 0 while pos < end: match = _etag_re.match(value, pos) if match is None: break is_weak, quoted, raw = match.groups() if raw == '*': return ETags(star_tag=True) elif quoted: raw = quoted if is_weak: weak.append(raw) else: strong.append(raw) pos = match.end() return ETags(strong, weak)
[docs]def generate_etag(data): """Generate an etag for some data.""" return md5(data).hexdigest()
[docs]def parse_date(value): """Parse one of the following date formats into a datetime object: .. sourcecode:: text Sun, 06 Nov 1994 08:49:37 GMT ; RFC 822, updated by RFC 1123 Sunday, 06-Nov-94 08:49:37 GMT ; RFC 850, obsoleted by RFC 1036 Sun Nov 6 08:49:37 1994 ; ANSI C's asctime() format If parsing fails the return value is `None`. :param value: a string with a supported date format. :return: a :class:`datetime.datetime` object. """ if value: t = parsedate_tz(value.strip()) if t is not None: try: year = t[0] # unfortunately that function does not tell us if two digit # years were part of the string, or if they were prefixed # with two zeroes. So what we do is to assume that 69-99 # refer to 1900, and everything below to 2000 if year >= 0 and year <= 68: year += 2000 elif year >= 69 and year <= 99: year += 1900 return datetime(*((year,) + t[1:7])) - \ timedelta(seconds=t[-1] or 0) except (ValueError, OverflowError): return None
def _dump_date(d, delim): """Used for `http_date` and `cookie_date`.""" if d is None: d = gmtime() elif isinstance(d, datetime): d = d.utctimetuple() elif isinstance(d, (integer_types, float)): d = gmtime(d) return '%s, %02d%s%s%s%s %02d:%02d:%02d GMT' % ( ('Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun')[d.tm_wday], d.tm_mday, delim, ('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec')[d.tm_mon - 1], delim, str(d.tm_year), d.tm_hour, d.tm_min, d.tm_sec )
[docs]def http_date(timestamp=None): """Formats the time to match the RFC1123 date format. Accepts a floating point number expressed in seconds since the epoch in, a datetime object or a timetuple. All times in UTC. The :func:`parse_date` function can be used to parse such a date. Outputs a string in the format ``Wdy, DD Mon YYYY HH:MM:SS GMT``. :param timestamp: If provided that date is used, otherwise the current. """ return _dump_date(timestamp, ' ')
[docs]def is_resource_modified(environ, etag=None, data=None, last_modified=None): """Convenience method for conditional requests. :param environ: the WSGI environment of the request to be checked. :param etag: the etag for the response for comparison. :param data: or alternatively the data of the response to automatically generate an etag using :func:`generate_etag`. :param last_modified: an optional date of the last modification. :return: `True` if the resource was modified, otherwise `False`. """ if etag is None and data is not None: etag = generate_etag(data) elif data is not None: raise TypeError('both data and etag given') if environ['REQUEST_METHOD'] not in ('GET', 'HEAD'): return False unmodified = False if isinstance(last_modified, string_types): last_modified = parse_date(last_modified) # ensure that microsecond is zero because the HTTP spec does not transmit # that either and we might have some false positives. See issue #39 if last_modified is not None: last_modified = last_modified.replace(microsecond=0) modified_since = parse_date(environ.get('HTTP_IF_MODIFIED_SINCE')) if modified_since and last_modified and last_modified <= modified_since: unmodified = True if etag: if_none_match = parse_etags(environ.get('HTTP_IF_NONE_MATCH')) if if_none_match: # # "A recipient MUST use the weak comparison function when comparing # entity-tags for If-None-Match" etag, _ = unquote_etag(etag) unmodified = if_none_match.contains_weak(etag) return not unmodified
[docs]def remove_entity_headers(headers, allowed=('expires', 'content-location')): """Remove all entity headers from a list or :class:`Headers` object. This operation works in-place. `Expires` and `Content-Location` headers are by default not removed. The reason for this is :rfc:`2616` section 10.3.5 which specifies some entity headers that should be sent. .. versionchanged:: 0.5 added `allowed` parameter. :param headers: a list or :class:`Headers` object. :param allowed: a list of headers that should still be allowed even though they are entity headers. """ allowed = set(x.lower() for x in allowed) headers[:] = [(key, value) for key, value in headers if not is_entity_header(key) or key.lower() in allowed]
[docs]def remove_hop_by_hop_headers(headers): """Remove all HTTP/1.1 "Hop-by-Hop" headers from a list or :class:`Headers` object. This operation works in-place. .. versionadded:: 0.5 :param headers: a list or :class:`Headers` object. """ headers[:] = [(key, value) for key, value in headers if not is_hop_by_hop_header(key)]
[docs]def is_entity_header(header): """Check if a header is an entity header. .. versionadded:: 0.5 :param header: the header to test. :return: `True` if it's an entity header, `False` otherwise. """ return header.lower() in _entity_headers
[docs]def is_hop_by_hop_header(header): """Check if a header is an HTTP/1.1 "Hop-by-Hop" header. .. versionadded:: 0.5 :param header: the header to test. :return: `True` if it's an entity header, `False` otherwise. """ return header.lower() in _hop_by_hop_headers
def is_byte_range_valid(start, stop, length): """Checks if a given byte content range is valid for the given length. .. versionadded:: 0.7 """ if (start is None) != (stop is None): return False elif start is None: return length is None or length >= 0 elif length is None: return 0 <= start < stop elif start >= stop: return False return 0 <= start < length # circular dependency fun from werkzeug.datastructures import Accept, HeaderSet, ETags, Authorization, \ WWWAuthenticate, TypeConversionDict, IfRange, Range, ContentRange, \ RequestCacheControl # DEPRECATED # backwards compatible imports from werkzeug.datastructures import ( # noqa MIMEAccept, CharsetAccept, LanguageAccept, Headers ) from werkzeug.urls import iri_to_uri