Fix constraint sync during migration
- restore constraints lost during merge in test schema.
- use constraint_by_eid in BeforeDeleteCWConstraintHook as done in
3.17.14 for BeforeDeleteConstrainedByHook. Fixes handling of multiple
constraints of the same type.
- make sync_schema_props_perms() delete the CWConstraint entity instead
of the constrained_by relation. In 3.19, the latter doesn't
automatically result in the former just because the relation is
composite. Simplify the constraint migration to delete all removed
constraints and recreate new ones even if they share the same type; that
optimization made the code more complicated for (AFAICT) no significant
reason.
# -*- coding: utf-8 -*-
# copyright 2014 Logilab, PARIS
"""A set of utility functions to handle CORS requests
Unless specified, all references in this file are related to:
http://www.w3.org/TR/cors
The provided implementation roughly follows:
http://www.html5rocks.com/static/images/cors_server_flowchart.png
See also:
https://developer.mozilla.org/en-US/docs/HTTP/Access_control_CORS
"""
import urlparse
from cubicweb.web import LOGGER
info = LOGGER.info
class CORSFailed(Exception):
"""Raised when cross origin resource sharing checks failed"""
class CORSPreflight(Exception):
"""Raised when cross origin resource sharing checks detects the
request as a valid preflight request"""
def process_request(req, config):
"""
Process a request to apply CORS specification algorithms
Check whether the CORS specification is respected and set corresponding
headers to ensure response complies with the specification.
In case of non-compliance, no CORS-related header is set.
"""
base_url = urlparse.urlsplit(req.base_url())
expected_host = '://'.join((base_url.scheme, base_url.netloc))
if not req.get_header('Origin') or req.get_header('Origin') == expected_host:
# not a CORS request, nothing to do
return
try:
# handle cross origin resource sharing (CORS)
if req.http_method() == 'OPTIONS':
if req.get_header('Access-Control-Request-Method'):
# preflight CORS request
process_preflight(req, config)
else: # Simple CORS or actual request
process_simple(req, config)
except CORSFailed, exc:
info('Cross origin resource sharing failed: %s' % exc)
except CORSPreflight:
info('Cross origin resource sharing: valid Preflight request %s')
raise
def process_preflight(req, config):
"""cross origin resource sharing (preflight)
Cf http://www.w3.org/TR/cors/#resource-preflight-requests
"""
origin = check_origin(req, config)
allowed_methods = set(config['access-control-allow-methods'])
allowed_headers = set(config['access-control-allow-headers'])
try:
method = req.get_header('Access-Control-Request-Method')
except ValueError:
raise CORSFailed('Access-Control-Request-Method is incorrect')
if method not in allowed_methods:
raise CORSFailed('Method is not allowed')
try:
req.get_header('Access-Control-Request-Headers', ())
except ValueError:
raise CORSFailed('Access-Control-Request-Headers is incorrect')
req.set_header('Access-Control-Allow-Methods', allowed_methods, raw=False)
req.set_header('Access-Control-Allow-Headers', allowed_headers, raw=False)
process_common(req, config, origin)
raise CORSPreflight()
def process_simple(req, config):
"""Handle the Simple Cross-Origin Request case
"""
origin = check_origin(req, config)
exposed_headers = config['access-control-expose-headers']
if exposed_headers:
req.set_header('Access-Control-Expose-Headers', exposed_headers, raw=False)
process_common(req, config, origin)
def process_common(req, config, origin):
req.set_header('Access-Control-Allow-Origin', origin)
# in CW, we always support credential/authentication
req.set_header('Access-Control-Allow-Credentials', 'true')
def check_origin(req, config):
origin = req.get_header('Origin').lower()
allowed_origins = config.get('access-control-allow-origin')
if not allowed_origins:
raise CORSFailed('access-control-allow-origin is not configured')
if '*' not in allowed_origins and origin not in allowed_origins:
raise CORSFailed('Origin is not allowed')
# bit of sanity check; see "6.3 Security"
myhost = urlparse.urlsplit(req.base_url()).netloc
host = req.get_header('Host')
if host != myhost:
info('cross origin resource sharing detected possible '
'DNS rebinding attack Host header != host of base_url: '
'%s != %s' % (host, myhost))
raise CORSFailed('Host header and hostname do not match')
# include "Vary: Origin" header (see 6.4)
req.set_header('Vary', 'Origin')
return origin