¡@
OpenStack Study: tempurl.py**** CubicPower OpenStack Study ****
# Copyright (c) 2010-2012 OpenStack Foundation # # 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. """ TempURL Middleware Allows the creation of URLs to provide temporary access to objects. For example, a website may wish to provide a link to download a large object in Swift, but the Swift account has no public access. The website can generate a URL that will provide GET access for a limited time to the resource. When the web browser user clicks on the link, the browser will download the object directly from Swift, obviating the need for the website to act as a proxy for the request. If the user were to share the link with all his friends, or accidentally post it on a forum, etc. the direct access would be limited to the expiration time set when the website created the link. To create such temporary URLs, first an X-Account-Meta-Temp-URL-Key header must be set on the Swift account. Then, an HMAC-SHA1 (RFC 2104) signature is generated using the HTTP method to allow (GET or PUT), the Unix timestamp the access should be allowed until, the full path to the object, and the key set on the account. For example, here is code generating the signature for a GET for 60 seconds on /v1/AUTH_account/container/object:: import hmac from hashlib import sha1 from time import time method = 'GET' expires = int(time() + 60) path = '/v1/AUTH_account/container/object' key = 'mykey' hmac_body = '%s\\n%s\\n%s' % (method, expires, path) sig = hmac.new(key, hmac_body, sha1).hexdigest() Be certain to use the full path, from the /v1/ onward. Let's say the sig ends up equaling da39a3ee5e6b4b0d3255bfef95601890afd80709 and expires ends up 1323479485. Then, for example, the website could provide a link to:: https://swift-cluster.example.com/v1/AUTH_account/container/object? temp_url_sig=da39a3ee5e6b4b0d3255bfef95601890afd80709& temp_url_expires=1323479485 Any alteration of the resource path or query arguments would result in 401 Unauthorized. Similary, a PUT where GET was the allowed method would 401. HEAD is allowed if GET or PUT is allowed. Using this in combination with browser form post translation middleware could also allow direct-from-browser uploads to specific locations in Swift. TempURL supports up to two keys, specified by X-Account-Meta-Temp-URL-Key and X-Account-Meta-Temp-URL-Key-2. Signatures are checked against both keys, if present. This is to allow for key rotation without invalidating all existing temporary URLs. With GET TempURLs, a Content-Disposition header will be set on the response so that browsers will interpret this as a file attachment to be saved. The filename chosen is based on the object name, but you can override this with a filename query parameter. Modifying the above example:: https://swift-cluster.example.com/v1/AUTH_account/container/object? temp_url_sig=da39a3ee5e6b4b0d3255bfef95601890afd80709& temp_url_expires=1323479485&filename=My+Test+File.pdf If you do not want the object to be downloaded, you can cause "Content-Disposition: inline" to be set on the response by adding the "inline" parameter to the query string, like so:: https://swift-cluster.example.com/v1/AUTH_account/container/object? temp_url_sig=da39a3ee5e6b4b0d3255bfef95601890afd80709& temp_url_expires=1323479485&inline """ __all__ = ['TempURL', 'filter_factory', 'DEFAULT_INCOMING_REMOVE_HEADERS', 'DEFAULT_INCOMING_ALLOW_HEADERS', 'DEFAULT_OUTGOING_REMOVE_HEADERS', 'DEFAULT_OUTGOING_ALLOW_HEADERS'] from os.path import basename from time import time from urllib import urlencode from urlparse import parse_qs from swift.proxy.controllers.base import get_account_info from swift.common.swob import HeaderKeyDict, HTTPUnauthorized from swift.common.utils import split_path, get_valid_utf8_str, \ register_swift_info, get_hmac, streq_const_time #: Default headers to remove from incoming requests. Simply a whitespace #: delimited list of header names and names can optionally end with '*' to #: indicate a prefix match. DEFAULT_INCOMING_ALLOW_HEADERS is a list of #: exceptions to these removals. DEFAULT_INCOMING_REMOVE_HEADERS = 'x-timestamp' #: Default headers as exceptions to DEFAULT_INCOMING_REMOVE_HEADERS. Simply a #: whitespace delimited list of header names and names can optionally end with #: '*' to indicate a prefix match. DEFAULT_INCOMING_ALLOW_HEADERS = '' #: Default headers to remove from outgoing responses. Simply a whitespace #: delimited list of header names and names can optionally end with '*' to #: indicate a prefix match. DEFAULT_OUTGOING_ALLOW_HEADERS is a list of #: exceptions to these removals. DEFAULT_OUTGOING_REMOVE_HEADERS = 'x-object-meta-*' #: Default headers as exceptions to DEFAULT_OUTGOING_REMOVE_HEADERS. Simply a #: whitespace delimited list of header names and names can optionally end with #: '*' to indicate a prefix match. DEFAULT_OUTGOING_ALLOW_HEADERS = 'x-object-meta-public-*'
**** CubicPower OpenStack Study **** def get_tempurl_keys_from_metadata(meta): """ Extracts the tempurl keys from metadata. :param meta: account metadata :returns: list of keys found (possibly empty if no keys set) Example: meta = get_account_info(...)['meta'] keys = get_tempurl_keys_from_metadata(meta) """ return [get_valid_utf8_str(value) for key, value in meta.iteritems() if key.lower() in ('temp-url-key', 'temp-url-key-2')]
**** CubicPower OpenStack Study **** class TempURL(object): """ WSGI Middleware to grant temporary URLs specific access to Swift resources. See the overview for more information. This middleware understands the following configuration settings:: incoming_remove_headers The headers to remove from incoming requests. Simply a whitespace delimited list of header names and names can optionally end with '*' to indicate a prefix match. incoming_allow_headers is a list of exceptions to these removals. Default: x-timestamp incoming_allow_headers The headers allowed as exceptions to incoming_remove_headers. Simply a whitespace delimited list of header names and names can optionally end with '*' to indicate a prefix match. Default: None outgoing_remove_headers The headers to remove from outgoing responses. Simply a whitespace delimited list of header names and names can optionally end with '*' to indicate a prefix match. outgoing_allow_headers is a list of exceptions to these removals. Default: x-object-meta-* outgoing_allow_headers The headers allowed as exceptions to outgoing_remove_headers. Simply a whitespace delimited list of header names and names can optionally end with '*' to indicate a prefix match. Default: x-object-meta-public-* The proxy logs created for any subrequests made will have swift.source set to "FP". :param app: The next WSGI filter or app in the paste.deploy chain. :param conf: The configuration dict for the middleware. """
**** CubicPower OpenStack Study **** def __init__(self, app, conf, methods=('GET', 'HEAD', 'PUT')): #: The next WSGI application/filter in the paste.deploy pipeline. self.app = app #: The filter configuration dict. self.conf = conf #: The methods allowed with Temp URLs. self.methods = methods headers = DEFAULT_INCOMING_REMOVE_HEADERS if 'incoming_remove_headers' in conf: headers = conf['incoming_remove_headers'] headers = \ ['HTTP_' + h.upper().replace('-', '_') for h in headers.split()] #: Headers to remove from incoming requests. Uppercase WSGI env style, #: like `HTTP_X_PRIVATE`. self.incoming_remove_headers = [h for h in headers if h[-1] != '*'] #: Header with match prefixes to remove from incoming requests. #: Uppercase WSGI env style, like `HTTP_X_SENSITIVE_*`. self.incoming_remove_headers_startswith = \ [h[:-1] for h in headers if h[-1] == '*'] headers = DEFAULT_INCOMING_ALLOW_HEADERS if 'incoming_allow_headers' in conf: headers = conf['incoming_allow_headers'] headers = \ ['HTTP_' + h.upper().replace('-', '_') for h in headers.split()] #: Headers to allow in incoming requests. Uppercase WSGI env style, #: like `HTTP_X_MATCHES_REMOVE_PREFIX_BUT_OKAY`. self.incoming_allow_headers = [h for h in headers if h[-1] != '*'] #: Header with match prefixes to allow in incoming requests. Uppercase #: WSGI env style, like `HTTP_X_MATCHES_REMOVE_PREFIX_BUT_OKAY_*`. self.incoming_allow_headers_startswith = \ [h[:-1] for h in headers if h[-1] == '*'] headers = DEFAULT_OUTGOING_REMOVE_HEADERS if 'outgoing_remove_headers' in conf: headers = conf['outgoing_remove_headers'] headers = [h.title() for h in headers.split()] #: Headers to remove from outgoing responses. Lowercase, like #: `x-account-meta-temp-url-key`. self.outgoing_remove_headers = [h for h in headers if h[-1] != '*'] #: Header with match prefixes to remove from outgoing responses. #: Lowercase, like `x-account-meta-private-*`. self.outgoing_remove_headers_startswith = \ [h[:-1] for h in headers if h[-1] == '*'] headers = DEFAULT_OUTGOING_ALLOW_HEADERS if 'outgoing_allow_headers' in conf: headers = conf['outgoing_allow_headers'] headers = [h.title() for h in headers.split()] #: Headers to allow in outgoing responses. Lowercase, like #: `x-matches-remove-prefix-but-okay`. self.outgoing_allow_headers = [h for h in headers if h[-1] != '*'] #: Header with match prefixes to allow in outgoing responses. #: Lowercase, like `x-matches-remove-prefix-but-okay-*`. self.outgoing_allow_headers_startswith = \ [h[:-1] for h in headers if h[-1] == '*'] #: HTTP user agent to use for subrequests. self.agent = '%(orig)s TempURL'
**** CubicPower OpenStack Study **** def __call__(self, env, start_response): """ Main hook into the WSGI paste.deploy filter/app pipeline. :param env: The WSGI environment dict. :param start_response: The WSGI start_response hook. :returns: Response as per WSGI. """ if env['REQUEST_METHOD'] == 'OPTIONS': return self.app(env, start_response) info = self._get_temp_url_info(env) temp_url_sig, temp_url_expires, filename, inline_disposition = info if temp_url_sig is None and temp_url_expires is None: return self.app(env, start_response) if not temp_url_sig or not temp_url_expires: return self._invalid(env, start_response) account = self._get_account(env) if not account: return self._invalid(env, start_response) keys = self._get_keys(env, account) if not keys: return self._invalid(env, start_response) if env['REQUEST_METHOD'] == 'HEAD': hmac_vals = ( self._get_hmacs(env, temp_url_expires, keys) + self._get_hmacs(env, temp_url_expires, keys, request_method='GET') + self._get_hmacs(env, temp_url_expires, keys, request_method='PUT')) else: hmac_vals = self._get_hmacs(env, temp_url_expires, keys) # While it's true that any() will short-circuit, this doesn't affect # the timing-attack resistance since the only way this will # short-circuit is when a valid signature is passed in. is_valid_hmac = any(streq_const_time(temp_url_sig, hmac) for hmac in hmac_vals) if not is_valid_hmac: return self._invalid(env, start_response) self._clean_incoming_headers(env) env['swift.authorize'] = lambda req: None env['swift.authorize_override'] = True env['REMOTE_USER'] = '.wsgi.tempurl' qs = {'temp_url_sig': temp_url_sig, 'temp_url_expires': temp_url_expires} if filename: qs['filename'] = filename env['QUERY_STRING'] = urlencode(qs) def _start_response(status, headers, exc_info=None): headers = self._clean_outgoing_headers(headers) if env['REQUEST_METHOD'] == 'GET' and status[0] == '2': # figure out the right value for content-disposition # 1) use the value from the query string # 2) use the value from the object metadata # 3) use the object name (default) out_headers = [] existing_disposition = None for h, v in headers: if h.lower() != 'content-disposition': out_headers.append((h, v)) else: existing_disposition = v if inline_disposition: disposition_value = 'inline' elif filename: disposition_value = 'attachment; filename="%s"' % ( filename.replace('"', '\\"')) elif existing_disposition: disposition_value = existing_disposition else: name = basename(env['PATH_INFO'].rstrip('/')) disposition_value = 'attachment; filename="%s"' % ( name.replace('"', '\\"')) out_headers.append(('Content-Disposition', disposition_value)) headers = out_headers return start_response(status, headers, exc_info) return self.app(env, _start_response)
**** CubicPower OpenStack Study **** def _start_response(status, headers, exc_info=None): headers = self._clean_outgoing_headers(headers) if env['REQUEST_METHOD'] == 'GET' and status[0] == '2': # figure out the right value for content-disposition # 1) use the value from the query string # 2) use the value from the object metadata # 3) use the object name (default) out_headers = [] existing_disposition = None for h, v in headers: if h.lower() != 'content-disposition': out_headers.append((h, v)) else: existing_disposition = v if inline_disposition: disposition_value = 'inline' elif filename: disposition_value = 'attachment; filename="%s"' % ( filename.replace('"', '\\"')) elif existing_disposition: disposition_value = existing_disposition else: name = basename(env['PATH_INFO'].rstrip('/')) disposition_value = 'attachment; filename="%s"' % ( name.replace('"', '\\"')) out_headers.append(('Content-Disposition', disposition_value)) headers = out_headers return start_response(status, headers, exc_info) return self.app(env, _start_response)
**** CubicPower OpenStack Study **** def _get_account(self, env): """ Returns just the account for the request, if it's an object request and one of the configured methods; otherwise, None is returned. :param env: The WSGI environment for the request. :returns: Account str or None. """ if env['REQUEST_METHOD'] in self.methods: try: ver, acc, cont, obj = split_path(env['PATH_INFO'], 4, 4, True) except ValueError: return None if ver == 'v1' and obj.strip('/'): return acc
**** CubicPower OpenStack Study **** def _get_temp_url_info(self, env): """ Returns the provided temporary URL parameters (sig, expires), if given and syntactically valid. Either sig or expires could be None if not provided. If provided, expires is also converted to an int if possible or 0 if not, and checked for expiration (returns 0 if expired). :param env: The WSGI environment for the request. :returns: (sig, expires, filename, inline) as described above. """ temp_url_sig = temp_url_expires = filename = inline = None qs = parse_qs(env.get('QUERY_STRING', ''), keep_blank_values=True) if 'temp_url_sig' in qs: temp_url_sig = qs['temp_url_sig'][0] if 'temp_url_expires' in qs: try: temp_url_expires = int(qs['temp_url_expires'][0]) except ValueError: temp_url_expires = 0 if temp_url_expires < time(): temp_url_expires = 0 if 'filename' in qs: filename = qs['filename'][0] if 'inline' in qs: inline = True return temp_url_sig, temp_url_expires, filename, inline
**** CubicPower OpenStack Study **** def _get_keys(self, env, account): """ Returns the X-Account-Meta-Temp-URL-Key[-2] header values for the account, or an empty list if none is set. Returns 0, 1, or 2 elements depending on how many keys are set in the account's metadata. :param env: The WSGI environment for the request. :param account: Account str. :returns: [X-Account-Meta-Temp-URL-Key str value if set, X-Account-Meta-Temp-URL-Key-2 str value if set] """ account_info = get_account_info(env, self.app, swift_source='TU') return get_tempurl_keys_from_metadata(account_info['meta'])
**** CubicPower OpenStack Study **** def _get_hmacs(self, env, expires, keys, request_method=None): """ :param env: The WSGI environment for the request. :param expires: Unix timestamp as an int for when the URL expires. :param keys: Key strings, from the X-Account-Meta-Temp-URL-Key[-2] of the account. :param request_method: Optional override of the request in the WSGI env. For example, if a HEAD does not match, you may wish to override with GET to still allow the HEAD. """ if not request_method: request_method = env['REQUEST_METHOD'] return [get_hmac( request_method, env['PATH_INFO'], expires, key) for key in keys]
**** CubicPower OpenStack Study **** def _invalid(self, env, start_response): """ Performs the necessary steps to indicate a WSGI 401 Unauthorized response to the request. :param env: The WSGI environment for the request. :param start_response: The WSGI start_response hook. :returns: 401 response as per WSGI. """ if env['REQUEST_METHOD'] == 'HEAD': body = None else: body = '401 Unauthorized: Temp URL invalid\n' return HTTPUnauthorized(body=body)(env, start_response)
**** CubicPower OpenStack Study **** def _clean_incoming_headers(self, env): """ Removes any headers from the WSGI environment as per the middleware configuration for incoming requests. :param env: The WSGI environment for the request. """ for h in env.keys(): remove = h in self.incoming_remove_headers if not remove: for p in self.incoming_remove_headers_startswith: if h.startswith(p): remove = True break if remove: if h in self.incoming_allow_headers: remove = False if remove: for p in self.incoming_allow_headers_startswith: if h.startswith(p): remove = False break if remove: del env[h]
**** CubicPower OpenStack Study **** def _clean_outgoing_headers(self, headers): """ Removes any headers as per the middleware configuration for outgoing responses. :param headers: A WSGI start_response style list of headers, [('header1', 'value), ('header2', 'value), ...] :returns: The same headers list, but with some headers removed as per the middlware configuration for outgoing responses. """ headers = HeaderKeyDict(headers) for h in headers.keys(): remove = h in self.outgoing_remove_headers if not remove: for p in self.outgoing_remove_headers_startswith: if h.startswith(p): remove = True break if remove: if h in self.outgoing_allow_headers: remove = False if remove: for p in self.outgoing_allow_headers_startswith: if h.startswith(p): remove = False break if remove: del headers[h] return headers.items() def filter_factory(global_conf, **local_conf): """Returns the WSGI filter for use with paste.deploy.""" conf = global_conf.copy() conf.update(local_conf) methods = conf.get('methods', 'GET HEAD PUT').split() register_swift_info('tempurl', methods=methods) return lambda app: TempURL(app, conf, methods=methods)
**** CubicPower OpenStack Study **** def filter_factory(global_conf, **local_conf): """Returns the WSGI filter for use with paste.deploy.""" conf = global_conf.copy() conf.update(local_conf) methods = conf.get('methods', 'GET HEAD PUT').split() register_swift_info('tempurl', methods=methods) return lambda app: TempURL(app, conf, methods=methods)
|