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# -*- coding: utf-8 -*-
This module implements WSGI related helpers.
:copyright: (c) 2014 by the Werkzeug Team, see AUTHORS for more details.
:license: BSD, see LICENSE for more details.
import io
import httplib
except ImportError:
from http import client as httplib
import mimetypes
import os
import posixpath
import re
import socket
from datetime import datetime
from functools import partial, update_wrapper
from itertools import chain
from time import mktime, time
from zlib import adler32
from werkzeug._compat import BytesIO, PY2, implements_iterator, iteritems, \
make_literal_wrapper, string_types, text_type, to_bytes, to_unicode, \
try_coerce_native, wsgi_get_bytes
from werkzeug._internal import _encode_idna
from werkzeug.filesystem import get_filesystem_encoding
from werkzeug.http import http_date, is_resource_modified, \
from werkzeug.urls import uri_to_iri, url_join, url_parse, url_quote
from werkzeug.datastructures import EnvironHeaders
def responder(f):
"""Marks a function as responder. Decorate a function with it and it
will automatically call the return value as WSGI application.
def application(environ, start_response):
return Response('Hello World!')
return update_wrapper(lambda *a: f(*a)(*a[-2:]), f)
def get_current_url(environ, root_only=False, strip_querystring=False,
host_only=False, trusted_hosts=None):
"""A handy helper function that recreates the full URL as IRI for the
current request or parts of it. Here's an example:
>>> from werkzeug.test import create_environ
>>> env = create_environ("/?param=foo", "http://localhost/script")
>>> get_current_url(env)
>>> get_current_url(env, root_only=True)
>>> get_current_url(env, host_only=True)
>>> get_current_url(env, strip_querystring=True)
This optionally it verifies that the host is in a list of trusted hosts.
If the host is not in there it will raise a
Note that the string returned might contain unicode characters as the
representation is an IRI not an URI. If you need an ASCII only
representation you can use the :func:`~werkzeug.urls.iri_to_uri`
>>> from werkzeug.urls import iri_to_uri
>>> iri_to_uri(get_current_url(env))
:param environ: the WSGI environment to get the current URL from.
:param root_only: set `True` if you only want the root URL.
:param strip_querystring: set to `True` if you don't want the querystring.
:param host_only: set to `True` if the host URL should be returned.
:param trusted_hosts: a list of trusted hosts, see :func:`host_is_trusted`
for more information.
tmp = [environ['wsgi.url_scheme'], '://', get_host(environ, trusted_hosts)]
cat = tmp.append
if host_only:
return uri_to_iri(''.join(tmp) + '/')
cat(url_quote(wsgi_get_bytes(environ.get('SCRIPT_NAME', ''))).rstrip('/'))
if not root_only:
cat(url_quote(wsgi_get_bytes(environ.get('PATH_INFO', '')).lstrip(b'/')))
if not strip_querystring:
qs = get_query_string(environ)
if qs:
cat('?' + qs)
return uri_to_iri(''.join(tmp))
def host_is_trusted(hostname, trusted_list):
"""Checks if a host is trusted against a list. This also takes care
of port normalization.
.. versionadded:: 0.9
:param hostname: the hostname to check
:param trusted_list: a list of hostnames to check against. If a
hostname starts with a dot it will match against
all subdomains as well.
if not hostname:
return False
if isinstance(trusted_list, string_types):
trusted_list = [trusted_list]
def _normalize(hostname):
if ':' in hostname:
hostname = hostname.rsplit(':', 1)[0]
return _encode_idna(hostname)
hostname = _normalize(hostname)
except UnicodeError:
return False
for ref in trusted_list:
if ref.startswith('.'):
ref = ref[1:]
suffix_match = True
suffix_match = False
ref = _normalize(ref)
except UnicodeError:
return False
if ref == hostname:
return True
if suffix_match and hostname.endswith(b'.' + ref):
return True
return False
def get_host(environ, trusted_hosts=None):
"""Return the host for the given WSGI environment. This first checks
the ``Host`` header. If it's not present, then ``SERVER_NAME`` and
``SERVER_PORT`` are used. The host will only contain the port if it
is different than the standard port for the protocol.
Optionally, verify that the host is trusted using
:func:`host_is_trusted` and raise a
:exc:`~werkzeug.exceptions.SecurityError` if it is not.
:param environ: The WSGI environment to get the host from.
:param trusted_hosts: A list of trusted hosts.
:return: Host, with port if necessary.
:raise ~werkzeug.exceptions.SecurityError: If the host is not
if 'HTTP_HOST' in environ:
rv = environ['HTTP_HOST']
if environ['wsgi.url_scheme'] == 'http' and rv.endswith(':80'):
rv = rv[:-3]
elif environ['wsgi.url_scheme'] == 'https' and rv.endswith(':443'):
rv = rv[:-4]
rv = environ['SERVER_NAME']
if (environ['wsgi.url_scheme'], environ['SERVER_PORT']) not \
in (('https', '443'), ('http', '80')):
rv += ':' + environ['SERVER_PORT']
if trusted_hosts is not None:
if not host_is_trusted(rv, trusted_hosts):
from werkzeug.exceptions import SecurityError
raise SecurityError('Host "%s" is not trusted' % rv)
return rv
def get_content_length(environ):
"""Returns the content length from the WSGI environment as
integer. If it's not available or chunked transfer encoding is used,
``None`` is returned.
.. versionadded:: 0.9
:param environ: the WSGI environ to fetch the content length from.
if environ.get('HTTP_TRANSFER_ENCODING', '') == 'chunked':
return None
content_length = environ.get('CONTENT_LENGTH')
if content_length is not None:
return max(0, int(content_length))
except (ValueError, TypeError):
def get_input_stream(environ, safe_fallback=True):
"""Returns the input stream from the WSGI environment and wraps it
in the most sensible way possible. The stream returned is not the
raw WSGI stream in most cases but one that is safe to read from
without taking into account the content length.
If content length is not set, the stream will be empty for safety reasons.
If the WSGI server supports chunked or infinite streams, it should set
the ``wsgi.input_terminated`` value in the WSGI environ to indicate that.
.. versionadded:: 0.9
:param environ: the WSGI environ to fetch the stream from.
:param safe_fallback: use an empty stream as a safe fallback when the
content length is not set. Disabling this allows infinite streams,
which can be a denial-of-service risk.
stream = environ['wsgi.input']
content_length = get_content_length(environ)
# A wsgi extension that tells us if the input is terminated. In
# that case we return the stream unchanged as we know we can safely
# read it until the end.
if environ.get('wsgi.input_terminated'):
return stream
# If the request doesn't specify a content length, returning the stream is
# potentially dangerous because it could be infinite, malicious or not. If
# safe_fallback is true, return an empty stream instead for safety.
if content_length is None:
return safe_fallback and BytesIO() or stream
# Otherwise limit the stream to the content length
return LimitedStream(stream, content_length)
def get_query_string(environ):
"""Returns the `QUERY_STRING` from the WSGI environment. This also takes
care about the WSGI decoding dance on Python 3 environments as a
native string. The string returned will be restricted to ASCII
.. versionadded:: 0.9
:param environ: the WSGI environment object to get the query string from.
qs = wsgi_get_bytes(environ.get('QUERY_STRING', ''))
# QUERY_STRING really should be ascii safe but some browsers
# will send us some unicode stuff (I am looking at you IE).
# In that case we want to urllib quote it badly.
return try_coerce_native(url_quote(qs, safe=':&%=+$!*\'(),'))
def get_path_info(environ, charset='utf-8', errors='replace'):
"""Returns the `PATH_INFO` from the WSGI environment and properly
decodes it. This also takes care about the WSGI decoding dance
on Python 3 environments. if the `charset` is set to `None` a
bytestring is returned.
.. versionadded:: 0.9
:param environ: the WSGI environment object to get the path from.
:param charset: the charset for the path info, or `None` if no
decoding should be performed.
:param errors: the decoding error handling.
path = wsgi_get_bytes(environ.get('PATH_INFO', ''))
return to_unicode(path, charset, errors, allow_none_charset=True)
def get_script_name(environ, charset='utf-8', errors='replace'):
"""Returns the `SCRIPT_NAME` from the WSGI environment and properly
decodes it. This also takes care about the WSGI decoding dance
on Python 3 environments. if the `charset` is set to `None` a
bytestring is returned.
.. versionadded:: 0.9
:param environ: the WSGI environment object to get the path from.
:param charset: the charset for the path, or `None` if no
decoding should be performed.
:param errors: the decoding error handling.
path = wsgi_get_bytes(environ.get('SCRIPT_NAME', ''))
return to_unicode(path, charset, errors, allow_none_charset=True)
def pop_path_info(environ, charset='utf-8', errors='replace'):
"""Removes and returns the next segment of `PATH_INFO`, pushing it onto
`SCRIPT_NAME`. Returns `None` if there is nothing left on `PATH_INFO`.
If the `charset` is set to `None` a bytestring is returned.
If there are empty segments (``'/foo//bar``) these are ignored but
properly pushed to the `SCRIPT_NAME`:
>>> env = {'SCRIPT_NAME': '/foo', 'PATH_INFO': '/a/b'}
>>> pop_path_info(env)
>>> env['SCRIPT_NAME']
>>> pop_path_info(env)
>>> env['SCRIPT_NAME']
.. versionadded:: 0.5
.. versionchanged:: 0.9
The path is now decoded and a charset and encoding
parameter can be provided.
:param environ: the WSGI environment that is modified.
path = environ.get('PATH_INFO')
if not path:
return None
script_name = environ.get('SCRIPT_NAME', '')
# shift multiple leading slashes over
old_path = path
path = path.lstrip('/')
if path != old_path:
script_name += '/' * (len(old_path) - len(path))
if '/' not in path:
environ['PATH_INFO'] = ''
environ['SCRIPT_NAME'] = script_name + path
rv = wsgi_get_bytes(path)
segment, path = path.split('/', 1)
environ['PATH_INFO'] = '/' + path
environ['SCRIPT_NAME'] = script_name + segment
rv = wsgi_get_bytes(segment)
return to_unicode(rv, charset, errors, allow_none_charset=True)
def peek_path_info(environ, charset='utf-8', errors='replace'):
"""Returns the next segment on the `PATH_INFO` or `None` if there
is none. Works like :func:`pop_path_info` without modifying the
>>> env = {'SCRIPT_NAME': '/foo', 'PATH_INFO': '/a/b'}
>>> peek_path_info(env)
>>> peek_path_info(env)
If the `charset` is set to `None` a bytestring is returned.
.. versionadded:: 0.5
.. versionchanged:: 0.9
The path is now decoded and a charset and encoding
parameter can be provided.
:param environ: the WSGI environment that is checked.
segments = environ.get('PATH_INFO', '').lstrip('/').split('/', 1)
if segments:
return to_unicode(wsgi_get_bytes(segments[0]),
charset, errors, allow_none_charset=True)
def extract_path_info(environ_or_baseurl, path_or_url, charset='utf-8',
errors='replace', collapse_http_schemes=True):
"""Extracts the path info from the given URL (or WSGI environment) and
path. The path info returned is a unicode string, not a bytestring
suitable for a WSGI environment. The URLs might also be IRIs.
If the path info could not be determined, `None` is returned.
Some examples:
>>> extract_path_info('', '/app/hello')
>>> extract_path_info('',
... '')
>>> extract_path_info('',
... '',
... collapse_http_schemes=False) is None
Instead of providing a base URL you can also pass a WSGI environment.
.. versionadded:: 0.6
:param environ_or_baseurl: a WSGI environment dict, a base URL or
base IRI. This is the root of the
:param path_or_url: an absolute path from the server root, a
relative path (in which case it's the path info)
or a full URL. Also accepts IRIs and unicode
:param charset: the charset for byte data in URLs
:param errors: the error handling on decode
:param collapse_http_schemes: if set to `False` the algorithm does
not assume that http and https on the
same server point to the same
def _normalize_netloc(scheme, netloc):
parts = netloc.split(u'@', 1)[-1].split(u':', 1)
if len(parts) == 2:
netloc, port = parts
if (scheme == u'http' and port == u'80') or \
(scheme == u'https' and port == u'443'):
port = None
netloc = parts[0]
port = None
if port is not None:
netloc += u':' + port
return netloc
# make sure whatever we are working on is a IRI and parse it
path = uri_to_iri(path_or_url, charset, errors)
if isinstance(environ_or_baseurl, dict):
environ_or_baseurl = get_current_url(environ_or_baseurl,
base_iri = uri_to_iri(environ_or_baseurl, charset, errors)
base_scheme, base_netloc, base_path = url_parse(base_iri)[:3]
cur_scheme, cur_netloc, cur_path, = \
url_parse(url_join(base_iri, path))[:3]
# normalize the network location
base_netloc = _normalize_netloc(base_scheme, base_netloc)
cur_netloc = _normalize_netloc(cur_scheme, cur_netloc)
# is that IRI even on a known HTTP scheme?
if collapse_http_schemes:
for scheme in base_scheme, cur_scheme:
if scheme not in (u'http', u'https'):
return None
if not (base_scheme in (u'http', u'https') and
base_scheme == cur_scheme):
return None
# are the netlocs compatible?
if base_netloc != cur_netloc:
return None
# are we below the application path?
base_path = base_path.rstrip(u'/')
if not cur_path.startswith(base_path):
return None
return u'/' + cur_path[len(base_path):].lstrip(u'/')
class ProxyMiddleware(object):
"""This middleware routes some requests to the provided WSGI app and
proxies some requests to an external server. This is not something that
can generally be done on the WSGI layer and some HTTP requests will not
tunnel through correctly (for instance websocket requests cannot be
proxied through WSGI). As a result this is only really useful for some
basic requests that can be forwarded.
Example configuration::
app = ProxyMiddleware(app, {
'/static/': {
'target': '',
For each host options can be specified. The following options are
the target URL to dispatch to
if set to `True` the prefix is chopped off the URL before
dispatching it to the server.
When set to ``'<auto>'`` which is the default the host header is
automatically rewritten to the URL of the target. If set to `None`
then the host header is unmodified from the client request. Any
other value overwrites the host header with that value.
An optional dictionary of headers that should be sent with the
request to the target host.
In case this is an HTTPS target host then an SSL context can be
provided here (:class:`ssl.SSLContext`). This can be used for instance
to disable SSL verification.
In this case everything below ``'/static/'`` is proxied to the server on
port 5001. The host header is automatically rewritten and so are request
URLs (eg: the leading `/static/` prefix here gets chopped off).
.. versionadded:: 0.14
def __init__(self, app, targets, chunk_size=2 << 13, timeout=10):
def _set_defaults(opts):
opts.setdefault('remove_prefix', False)
opts.setdefault('host', '<auto>')
opts.setdefault('headers', {})
opts.setdefault('ssl_context', None)
return opts = app
self.targets = dict(('/%s/' % k.strip('/'), _set_defaults(v))
for k, v in iteritems(targets))
self.chunk_size = chunk_size
self.timeout = timeout
def proxy_to(self, opts, path, prefix):
target = url_parse(opts['target'])
def application(environ, start_response):
headers = list(EnvironHeaders(environ).items())
headers[:] = [(k, v) for k, v in headers
if not is_hop_by_hop_header(k) and
k.lower() not in ('content-length', 'host')]
headers.append(('Connection', 'close'))
if opts['host'] == '<auto>':
headers.append(('Host', target.ascii_host))
elif opts['host'] is None:
headers.append(('Host', environ['HTTP_HOST']))
headers.append(('Host', opts['host']))
remote_path = path
if opts['remove_prefix']:
remote_path = '%s/%s' % (
content_length = environ.get('CONTENT_LENGTH')
chunked = False
if content_length not in ('', None):
headers.append(('Content-Length', content_length))
elif content_length is not None:
headers.append(('Transfer-Encoding', 'chunked'))
chunked = True
if target.scheme == 'http':
con = httplib.HTTPConnection(
target.ascii_host, target.port or 80,
elif target.scheme == 'https':
con = httplib.HTTPSConnection(
target.ascii_host, target.port or 443,
remote_url = url_quote(remote_path)
querystring = environ['QUERY_STRING']
if querystring:
remote_url = remote_url + '?' + querystring
con.putrequest(environ['REQUEST_METHOD'], remote_url,
for k, v in headers:
if k.lower() == 'connection':
v = 'close'
con.putheader(k, v)
stream = get_input_stream(environ)
while 1:
data =
if not data:
if chunked:
con.send(b'%x\r\n%s\r\n' % (len(data), data))
resp = con.getresponse()
except socket.error:
from werkzeug.exceptions import BadGateway
return BadGateway()(environ, start_response)
start_response('%d %s' % (resp.status, resp.reason),
[(k.title(), v) for k, v in resp.getheaders()
if not is_hop_by_hop_header(k)])
def read():
while 1:
data =
except socket.error:
if not data:
yield data
return read()
return application
def __call__(self, environ, start_response):
path = environ['PATH_INFO']
app =
for prefix, opts in iteritems(self.targets):
if path.startswith(prefix):
app = self.proxy_to(opts, path, prefix)
return app(environ, start_response)
class SharedDataMiddleware(object):
"""A WSGI middleware that provides static content for development
environments or simple server setups. Usage is quite simple::
import os
from werkzeug.wsgi import SharedDataMiddleware
app = SharedDataMiddleware(app, {
'/shared': os.path.join(os.path.dirname(__file__), 'shared')
The contents of the folder ``./shared`` will now be available on
````. This is pretty useful during development
because a standalone media server is not required. One can also mount
files on the root folder and still continue to use the application because
the shared data middleware forwards all unhandled requests to the
application, even if the requests are below one of the shared folders.
If `pkg_resources` is available you can also tell the middleware to serve
files from package data::
app = SharedDataMiddleware(app, {
'/shared': ('myapplication', 'shared_files')
This will then serve the ``shared_files`` folder in the `myapplication`
Python package.
The optional `disallow` parameter can be a list of :func:`~fnmatch.fnmatch`
rules for files that are not accessible from the web. If `cache` is set to
`False` no caching headers are sent.
Currently the middleware does not support non ASCII filenames. If the
encoding on the file system happens to be the encoding of the URI it may
work but this could also be by accident. We strongly suggest using ASCII
only file names for static files.
The middleware will guess the mimetype using the Python `mimetype`
module. If it's unable to figure out the charset it will fall back
to `fallback_mimetype`.
.. versionchanged:: 0.5
The cache timeout is configurable now.
.. versionadded:: 0.6
The `fallback_mimetype` parameter was added.
:param app: the application to wrap. If you don't want to wrap an
application you can pass it :exc:`NotFound`.
:param exports: a list or dict of exported files and folders.
:param disallow: a list of :func:`~fnmatch.fnmatch` rules.
:param fallback_mimetype: the fallback mimetype for unknown files.
:param cache: enable or disable caching headers.
:param cache_timeout: the cache timeout in seconds for the headers.
def __init__(self, app, exports, disallow=None, cache=True,
cache_timeout=60 * 60 * 12, fallback_mimetype='text/plain'): = app
self.exports = []
self.cache = cache
self.cache_timeout = cache_timeout
if hasattr(exports, 'items'):
exports = iteritems(exports)
for key, value in exports:
if isinstance(value, tuple):
loader = self.get_package_loader(*value)
elif isinstance(value, string_types):
if os.path.isfile(value):
loader = self.get_file_loader(value)
loader = self.get_directory_loader(value)
raise TypeError('unknown def %r' % value)
self.exports.append((key, loader))
if disallow is not None:
from fnmatch import fnmatch
self.is_allowed = lambda x: not fnmatch(x, disallow)
self.fallback_mimetype = fallback_mimetype
def is_allowed(self, filename):
"""Subclasses can override this method to disallow the access to
certain files. However by providing `disallow` in the constructor
this method is overwritten.
return True
def _opener(self, filename):
return lambda: (
open(filename, 'rb'),
def get_file_loader(self, filename):
return lambda x: (os.path.basename(filename), self._opener(filename))
def get_package_loader(self, package, package_path):
from pkg_resources import DefaultProvider, ResourceManager, \
loadtime = datetime.utcnow()
provider = get_provider(package)
manager = ResourceManager()
filesystem_bound = isinstance(provider, DefaultProvider)
def loader(path):
if path is None:
return None, None
path = posixpath.join(package_path, path)
if not provider.has_resource(path):
return None, None
basename = posixpath.basename(path)
if filesystem_bound:
return basename, self._opener(
provider.get_resource_filename(manager, path))
s = provider.get_resource_string(manager, path)
return basename, lambda: (
return loader
def get_directory_loader(self, directory):
def loader(path):
if path is not None:
path = os.path.join(directory, path)
path = directory
if os.path.isfile(path):
return os.path.basename(path), self._opener(path)
return None, None
return loader
def generate_etag(self, mtime, file_size, real_filename):
if not isinstance(real_filename, bytes):
real_filename = real_filename.encode(get_filesystem_encoding())
return 'wzsdm-%d-%s-%s' % (
adler32(real_filename) & 0xffffffff
def __call__(self, environ, start_response):
cleaned_path = get_path_info(environ)
if PY2:
cleaned_path = cleaned_path.encode(get_filesystem_encoding())
# sanitize the path for non unix systems
cleaned_path = cleaned_path.strip('/')
for sep in os.sep, os.altsep:
if sep and sep != '/':
cleaned_path = cleaned_path.replace(sep, '/')
path = '/' + '/'.join(x for x in cleaned_path.split('/')
if x and x != '..')
file_loader = None
for search_path, loader in self.exports:
if search_path == path:
real_filename, file_loader = loader(None)
if file_loader is not None:
if not search_path.endswith('/'):
search_path += '/'
if path.startswith(search_path):
real_filename, file_loader = loader(path[len(search_path):])
if file_loader is not None:
if file_loader is None or not self.is_allowed(real_filename):
return, start_response)
guessed_type = mimetypes.guess_type(real_filename)
mime_type = guessed_type[0] or self.fallback_mimetype
f, mtime, file_size = file_loader()
headers = [('Date', http_date())]
if self.cache:
timeout = self.cache_timeout
etag = self.generate_etag(mtime, file_size, real_filename)
headers += [
('Etag', '"%s"' % etag),
('Cache-Control', 'max-age=%d, public' % timeout)
if not is_resource_modified(environ, etag, last_modified=mtime):
start_response('304 Not Modified', headers)
return []
headers.append(('Expires', http_date(time() + timeout)))
headers.append(('Cache-Control', 'public'))
('Content-Type', mime_type),
('Content-Length', str(file_size)),
('Last-Modified', http_date(mtime))
start_response('200 OK', headers)
return wrap_file(environ, f)
class DispatcherMiddleware(object):
"""Allows one to mount middlewares or applications in a WSGI application.
This is useful if you want to combine multiple WSGI applications::
app = DispatcherMiddleware(app, {
'/app2': app2,
'/app3': app3
def __init__(self, app, mounts=None): = app
self.mounts = mounts or {}
def __call__(self, environ, start_response):
script = environ.get('PATH_INFO', '')
path_info = ''
while '/' in script:
if script in self.mounts:
app = self.mounts[script]
script, last_item = script.rsplit('/', 1)
path_info = '/%s%s' % (last_item, path_info)
app = self.mounts.get(script,
original_script_name = environ.get('SCRIPT_NAME', '')
environ['SCRIPT_NAME'] = original_script_name + script
environ['PATH_INFO'] = path_info
return app(environ, start_response)
class ClosingIterator(object):
"""The WSGI specification requires that all middlewares and gateways
respect the `close` callback of the iterable returned by the application.
Because it is useful to add another close action to a returned iterable
and adding a custom iterable is a boring task this class can be used for
return ClosingIterator(app(environ, start_response), [cleanup_session,
If there is just one close function it can be passed instead of the list.
A closing iterator is not needed if the application uses response objects
and finishes the processing if the response is started::
return response(environ, start_response)
def __init__(self, iterable, callbacks=None):
iterator = iter(iterable)
self._next = partial(next, iterator)
if callbacks is None:
callbacks = []
elif callable(callbacks):
callbacks = [callbacks]
callbacks = list(callbacks)
iterable_close = getattr(iterable, 'close', None)
if iterable_close:
callbacks.insert(0, iterable_close)
self._callbacks = callbacks
def __iter__(self):
return self
def __next__(self):
return self._next()
def close(self):
for callback in self._callbacks:
def wrap_file(environ, file, buffer_size=8192):
"""Wraps a file. This uses the WSGI server's file wrapper if available
or otherwise the generic :class:`FileWrapper`.
.. versionadded:: 0.5
If the file wrapper from the WSGI server is used it's important to not
iterate over it from inside the application but to pass it through
unchanged. If you want to pass out a file wrapper inside a response
object you have to set :attr:`~BaseResponse.direct_passthrough` to `True`.
More information about file wrappers are available in :pep:`333`.
:param file: a :class:`file`-like object with a :meth:`` method.
:param buffer_size: number of bytes for one iteration.
return environ.get('wsgi.file_wrapper', FileWrapper)(file, buffer_size)
class FileWrapper(object):
"""This class can be used to convert a :class:`file`-like object into
an iterable. It yields `buffer_size` blocks until the file is fully
You should not use this class directly but rather use the
:func:`wrap_file` function that uses the WSGI server's file wrapper
support if it's available.
.. versionadded:: 0.5
If you're using this object together with a :class:`BaseResponse` you have
to use the `direct_passthrough` mode.
:param file: a :class:`file`-like object with a :meth:`` method.
:param buffer_size: number of bytes for one iteration.
def __init__(self, file, buffer_size=8192):
self.file = file
self.buffer_size = buffer_size
def close(self):
if hasattr(self.file, 'close'):
def seekable(self):
if hasattr(self.file, 'seekable'):
return self.file.seekable()
if hasattr(self.file, 'seek'):
return True
return False
def seek(self, *args):
if hasattr(self.file, 'seek'):*args)
def tell(self):
if hasattr(self.file, 'tell'):
return self.file.tell()
return None
def __iter__(self):
return self
def __next__(self):
data =
if data:
return data
raise StopIteration()
class _RangeWrapper(object):
# private for now, but should we make it public in the future ?
"""This class can be used to convert an iterable object into
an iterable that will only yield a piece of the underlying content.
It yields blocks until the underlying stream range is fully read.
The yielded blocks will have a size that can't exceed the original
iterator defined block size, but that can be smaller.
If you're using this object together with a :class:`BaseResponse` you have
to use the `direct_passthrough` mode.
:param iterable: an iterable object with a :meth:`__next__` method.
:param start_byte: byte from which read will start.
:param byte_range: how many bytes to read.
def __init__(self, iterable, start_byte=0, byte_range=None):
self.iterable = iter(iterable)
self.byte_range = byte_range
self.start_byte = start_byte
self.end_byte = None
if byte_range is not None:
self.end_byte = self.start_byte + self.byte_range
self.read_length = 0
self.seekable = hasattr(iterable, 'seekable') and iterable.seekable()
self.end_reached = False
def __iter__(self):
return self
def _next_chunk(self):
chunk = next(self.iterable)
self.read_length += len(chunk)
return chunk
except StopIteration:
self.end_reached = True
def _first_iteration(self):
chunk = None
if self.seekable:
self.read_length = self.iterable.tell()
contextual_read_length = self.read_length
while self.read_length <= self.start_byte:
chunk = self._next_chunk()
if chunk is not None:
chunk = chunk[self.start_byte - self.read_length:]
contextual_read_length = self.start_byte
return chunk, contextual_read_length
def _next(self):
if self.end_reached:
raise StopIteration()
chunk = None
contextual_read_length = self.read_length
if self.read_length == 0:
chunk, contextual_read_length = self._first_iteration()
if chunk is None:
chunk = self._next_chunk()
if self.end_byte is not None and self.read_length >= self.end_byte:
self.end_reached = True
return chunk[:self.end_byte - contextual_read_length]
return chunk
def __next__(self):
chunk = self._next()
if chunk:
return chunk
self.end_reached = True
raise StopIteration()
def close(self):
if hasattr(self.iterable, 'close'):
def _make_chunk_iter(stream, limit, buffer_size):
"""Helper for the line and chunk iter functions."""
if isinstance(stream, (bytes, bytearray, text_type)):
raise TypeError('Passed a string or byte object instead of '
'true iterator or stream.')
if not hasattr(stream, 'read'):
for item in stream:
if item:
yield item
if not isinstance(stream, LimitedStream) and limit is not None:
stream = LimitedStream(stream, limit)
_read =
while 1:
item = _read(buffer_size)
if not item:
yield item
def make_line_iter(stream, limit=None, buffer_size=10 * 1024,
"""Safely iterates line-based over an input stream. If the input stream
is not a :class:`LimitedStream` the `limit` parameter is mandatory.
This uses the stream's :meth:`` method internally as opposite
to the :meth:`~file.readline` method that is unsafe and can only be used
in violation of the WSGI specification. The same problem applies to the
`__iter__` function of the input stream which calls :meth:`~file.readline`
without arguments.
If you need line-by-line processing it's strongly recommended to iterate
over the input stream using this helper function.
.. versionchanged:: 0.8
This function now ensures that the limit was reached.
.. versionadded:: 0.9
added support for iterators as input stream.
.. versionadded:: 0.11.10
added support for the `cap_at_buffer` parameter.
:param stream: the stream or iterate to iterate over.
:param limit: the limit in bytes for the stream. (Usually
content length. Not necessary if the `stream`
is a :class:`LimitedStream`.
:param buffer_size: The optional buffer size.
:param cap_at_buffer: if this is set chunks are split if they are longer
than the buffer size. Internally this is implemented
that the buffer size might be exhausted by a factor
of two however.
_iter = _make_chunk_iter(stream, limit, buffer_size)
first_item = next(_iter, '')
if not first_item:
s = make_literal_wrapper(first_item)
empty = s('')
cr = s('\r')
lf = s('\n')
crlf = s('\r\n')
_iter = chain((first_item,), _iter)
def _iter_basic_lines():
_join = empty.join
buffer = []
while 1:
new_data = next(_iter, '')
if not new_data:
new_buf = []
buf_size = 0
for item in chain(buffer, new_data.splitlines(True)):
buf_size += len(item)
if item and item[-1:] in crlf:
yield _join(new_buf)
new_buf = []
elif cap_at_buffer and buf_size >= buffer_size:
rv = _join(new_buf)
while len(rv) >= buffer_size:
yield rv[:buffer_size]
rv = rv[buffer_size:]
new_buf = [rv]
buffer = new_buf
if buffer:
yield _join(buffer)
# This hackery is necessary to merge 'foo\r' and '\n' into one item
# of 'foo\r\n' if we were unlucky and we hit a chunk boundary.
previous = empty
for item in _iter_basic_lines():
if item == lf and previous[-1:] == cr:
previous += item
item = empty
if previous:
yield previous
previous = item
if previous:
yield previous
def make_chunk_iter(stream, separator, limit=None, buffer_size=10 * 1024,
"""Works like :func:`make_line_iter` but accepts a separator
which divides chunks. If you want newline based processing
you should use :func:`make_line_iter` instead as it
supports arbitrary newline markers.
.. versionadded:: 0.8
.. versionadded:: 0.9
added support for iterators as input stream.
.. versionadded:: 0.11.10
added support for the `cap_at_buffer` parameter.
:param stream: the stream or iterate to iterate over.
:param separator: the separator that divides chunks.
:param limit: the limit in bytes for the stream. (Usually
content length. Not necessary if the `stream`
is otherwise already limited).
:param buffer_size: The optional buffer size.
:param cap_at_buffer: if this is set chunks are split if they are longer
than the buffer size. Internally this is implemented
that the buffer size might be exhausted by a factor
of two however.
_iter = _make_chunk_iter(stream, limit, buffer_size)
first_item = next(_iter, '')
if not first_item:
_iter = chain((first_item,), _iter)
if isinstance(first_item, text_type):
separator = to_unicode(separator)
_split = re.compile(r'(%s)' % re.escape(separator)).split
_join = u''.join
separator = to_bytes(separator)
_split = re.compile(b'(' + re.escape(separator) + b')').split
_join = b''.join
buffer = []
while 1:
new_data = next(_iter, '')
if not new_data:
chunks = _split(new_data)
new_buf = []
buf_size = 0
for item in chain(buffer, chunks):
if item == separator:
yield _join(new_buf)
new_buf = []
buf_size = 0
buf_size += len(item)
if cap_at_buffer and buf_size >= buffer_size:
rv = _join(new_buf)
while len(rv) >= buffer_size:
yield rv[:buffer_size]
rv = rv[buffer_size:]
new_buf = [rv]
buf_size = len(rv)
buffer = new_buf
if buffer:
yield _join(buffer)
class LimitedStream(io.IOBase):
"""Wraps a stream so that it doesn't read more than n bytes. If the
stream is exhausted and the caller tries to get more bytes from it
:func:`on_exhausted` is called which by default returns an empty
string. The return value of that function is forwarded
to the reader function. So if it returns an empty string
:meth:`read` will return an empty string as well.
The limit however must never be higher than what the stream can
output. Otherwise :meth:`readlines` will try to read past the
.. admonition:: Note on WSGI compliance
calls to :meth:`readline` and :meth:`readlines` are not
WSGI compliant because it passes a size argument to the
readline methods. Unfortunately the WSGI PEP is not safely
implementable without a size argument to :meth:`readline`
because there is no EOF marker in the stream. As a result
of that the use of :meth:`readline` is discouraged.
For the same reason iterating over the :class:`LimitedStream`
is not portable. It internally calls :meth:`readline`.
We strongly suggest using :meth:`read` only or using the
:func:`make_line_iter` which safely iterates line-based
over a WSGI input stream.
:param stream: the stream to wrap.
:param limit: the limit for the stream, must not be longer than
what the string can provide if the stream does not
end with `EOF` (like `wsgi.input`)
def __init__(self, stream, limit):
self._read =
self._readline = stream.readline
self._pos = 0
self.limit = limit
def __iter__(self):
return self
def is_exhausted(self):
"""If the stream is exhausted this attribute is `True`."""
return self._pos >= self.limit
def on_exhausted(self):
"""This is called when the stream tries to read past the limit.
The return value of this function is returned from the reading
# Read null bytes from the stream so that we get the
# correct end of stream marker.
return self._read(0)
def on_disconnect(self):
"""What should happen if a disconnect is detected? The return
value of this function is returned from read functions in case
the client went away. By default a
:exc:`~werkzeug.exceptions.ClientDisconnected` exception is raised.
from werkzeug.exceptions import ClientDisconnected
raise ClientDisconnected()
def exhaust(self, chunk_size=1024 * 64):
"""Exhaust the stream. This consumes all the data left until the
limit is reached.
:param chunk_size: the size for a chunk. It will read the chunk
until the stream is exhausted and throw away
the results.
to_read = self.limit - self._pos
chunk = chunk_size
while to_read > 0:
chunk = min(to_read, chunk)
to_read -= chunk
def read(self, size=None):
"""Read `size` bytes or if size is not provided everything is read.
:param size: the number of bytes read.
if self._pos >= self.limit:
return self.on_exhausted()
if size is None or size == -1: # -1 is for consistence with file
size = self.limit
to_read = min(self.limit - self._pos, size)
read = self._read(to_read)
except (IOError, ValueError):
return self.on_disconnect()
if to_read and len(read) != to_read:
return self.on_disconnect()
self._pos += len(read)
return read
def readline(self, size=None):
"""Reads one line from the stream."""
if self._pos >= self.limit:
return self.on_exhausted()
if size is None:
size = self.limit - self._pos
size = min(size, self.limit - self._pos)
line = self._readline(size)
except (ValueError, IOError):
return self.on_disconnect()
if size and not line:
return self.on_disconnect()
self._pos += len(line)
return line
def readlines(self, size=None):
"""Reads a file into a list of strings. It calls :meth:`readline`
until the file is read to the end. It does support the optional
`size` argument if the underlaying stream supports it for
last_pos = self._pos
result = []
if size is not None:
end = min(self.limit, last_pos + size)
end = self.limit
while 1:
if size is not None:
size -= last_pos - self._pos
if self._pos >= end:
if size is not None:
last_pos = self._pos
return result
def tell(self):
"""Returns the position of the stream.
.. versionadded:: 0.9
return self._pos
def __next__(self):
line = self.readline()
if not line:
raise StopIteration()
return line
def readable(self):
return True