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webinterface_handler.py
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Sun, Jun 30, 09:57

webinterface_handler.py
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# -*- coding: utf-8 -*-
## $Id$
## This file is part of CDS Invenio.
## Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007 CERN.
##
## CDS Invenio is free software; you can redistribute it and/or
## modify it under the terms of the GNU General Public License as
## published by the Free Software Foundation; either version 2 of the
## License, or (at your option) any later version.
##
## CDS Invenio is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with CDS Invenio; if not, write to the Free Software Foundation, Inc.,
## 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
"""
Apache request handler mechanism.
It gives the tools to map url to functions, handles the legacy url
scheme (/search.py queries), HTTP/HTTPS switching, language
specification,...
"""
__revision__ = "$Id$"
import os
import urlparse
import base64
# The following mod_python imports are done separately in a particular
# order (util first) because I was getting sometimes publisher import
# error when testing weird situations, preventing util from being
# imported and leading to a traceback later. When this happened,
# importing util was okay, only publisher import caused troubles, so
# that importing in special order prevents these problems.
try:
from mod_python import util
from mod_python import apache
from mod_python import publisher
except ImportError:
pass
from invenio.config import cdslang, weburl, sweburl
from invenio.messages import wash_language
from invenio.urlutils import redirect_to_url
has_https_support = weburl != sweburl
DEBUG = False
def _debug(msg):
if DEBUG:
apache.log_error(msg, apache.APLOG_WARNING)
return
def _check_result(req, result):
""" Check that a page handler actually wrote something, and
properly finish the apache request."""
if result or req.bytes_sent > 0 or req.next:
if result is None:
result = ""
else:
result = str(result)
# unless content_type was manually set, we will attempt
# to guess it
if not req._content_type_set:
# make an attempt to guess content-type
if result[:100].strip()[:6].lower() == '<html>' \
or result.find('</') > 0:
req.content_type = 'text/html'
else:
req.content_type = 'text/plain'
if req.method != "HEAD":
req.write(result)
else:
req.write("")
return apache.OK
else:
req.log_error("mod_python.publisher: %s returned nothing." % `object`)
return apache.HTTP_INTERNAL_SERVER_ERROR
class TraversalError(Exception):
pass
class WebInterfaceDirectory(object):
""" A directory groups web pages, and can delegate dispatching of
requests to the actual handler. This has been heavily borrowed
from Quixote's dispatching mechanism, with specific adaptations."""
# Lists the valid URLs contained in this directory.
_exports = []
# Set this to True in order to redirect queries over HTTPS
_force_https = False
def _translate(self, component):
"""(component : string) -> string | None
Translate a path component into a Python identifier. Returning
None signifies that the component does not exist.
"""
if component in self._exports:
if component == '':
return 'index' # implicit mapping
else:
return component
else:
# check for an explicit external to internal mapping
for value in self._exports:
if isinstance(value, tuple):
if value[0] == component:
return value[1]
else:
return None
def _lookup(self, component, path):
""" Override this method if you need to map dynamic URLs.
It can eat up as much of the remaining path as needed, and
return the remaining parts, so that the traversal can
continue.
"""
return None, path
def _traverse(self, req, path):
""" Locate the handler of an URI by traversing the elements of
the path."""
_debug('traversing %r' % path)
component, path = path[0], path[1:]
name = self._translate(component)
if name is None:
obj, path = self._lookup(component, path)
else:
obj = getattr(self, name)
if obj is None:
_debug('could not resolve %s' % repr((component, path)))
raise TraversalError()
# We have found the next segment. If we know that from this
# point our subpages are over HTTPS, do the switch.
if has_https_support and self._force_https:
is_over_https = req.subprocess_env.has_key('HTTPS') \
and req.subprocess_env['HTTPS'] == 'on'
if not is_over_https:
# We need to isolate the part of the URI that is after
# weburl, and append that to our sweburl.
original_parts = urlparse.urlparse(req.unparsed_uri)
plain_prefix_parts = urlparse.urlparse(weburl)
secure_prefix_parts = urlparse.urlparse(sweburl)
# Compute the new path
plain_path = original_parts[2]
plain_path = secure_prefix_parts[2] + plain_path[len(plain_prefix_parts[2]):]
# ...and recompose the complete URL
final_parts = list(secure_prefix_parts)
final_parts[2] = plain_path
final_parts[-3:] = original_parts[-3:]
target = urlparse.urlunparse(final_parts)
return redirect_to_url(req, target)
# Continue the traversal. If there is a path, continue
# resolving, otherwise call the method as it is our final
# renderer. We even pass it the parsed form arguments.
if path:
return obj._traverse(req, path)
form = util.FieldStorage(req, keep_blank_values=True)
result = obj(req, form)
return _check_result(req, result)
def __call__(self, req, form):
""" Maybe resolve the final / of a directory """
# When this method is called, we either are a directory which
# has an 'index' method, and we redirect to it, or we don't
# have such a method, in which case it is a traversal error.
if "" in self._exports:
if not form:
# Fix missing trailing slash as a convenience, unless
# we are processing a form (in which case it is better
# to fix the form posting).
util.redirect(req, req.uri + "/", permanent=True)
_debug('directory %r is not callable' % self)
raise TraversalError()
def create_handler(root):
""" Return a handler function that will dispatch apache requests
through the URL layout passed in parameter."""
def _handler(req):
""" This handler is invoked by mod_python with the apache request."""
req.allow_methods(["GET", "POST"])
if req.method not in ["GET", "POST"]:
raise apache.SERVER_RETURN, apache.HTTP_METHOD_NOT_ALLOWED
try:
uri = req.uri
if uri == '/':
path = ['']
else:
path = uri[1:].split('/')
return root._traverse(req, path)
except TraversalError:
return apache.HTTP_NOT_FOUND
# Serve an error by default.
return apache.HTTP_NOT_FOUND
return _handler
def http_get_credentials(req, realm="restricted collection"):
if req.headers_in.has_key("Authorization"):
try:
s = req.headers_in["Authorization"][6:]
s = base64.decodestring(s)
user, passwd = s.split(":", 1)
except (ValueError, base64.binascii.Error, base64.binascii.Incomplete):
raise apache.SERVER_RETURN, apache.HTTP_BAD_REQUEST
return (user, passwd)
return (None, None)
def http_check_credentials(req, realm, check_auth):
authorized = False
if req.headers_in.has_key("Authorization"):
try:
s = req.headers_in["Authorization"][6:]
s = base64.decodestring(s)
user, passwd = s.split(":", 1)
except (ValueError, base64.binascii.Error, base64.binascii.Incomplete):
raise apache.SERVER_RETURN, apache.HTTP_BAD_REQUEST
authorized = check_auth(user, passwd)
if not authorized:
# note that Opera supposedly doesn't like spaces around "=" below
s = 'Basic realm="%s"' % realm
req.err_headers_out["WWW-Authenticate"] = s
raise apache.SERVER_RETURN, apache.HTTP_UNAUTHORIZED
return
def wash_urlargd(form, content):
"""
Wash the complete form based on the specification in
content. Content is a dictionary containing the field names as a
key, and a tuple (type, default) as value.
'type' can be list, str, int, tuple, dict or mod_python.util.Field
(for file uploads).
The specification automatically includes the 'ln' field, which is
common to all queries.
Arguments that are not defined in 'content' are discarded.
@Return: a dictionary that can be used for passing function
parameters by keywords.
"""
result = {}
content['ln'] = (str, cdslang)
for k, (dst_type, default) in content.items():
try:
value = form[k]
except KeyError:
result[k] = default
continue
src_type = type(value)
# First, handle the case where we want all the results. In
# this case, we need to ensure all the elements are strings,
# and not Field instances.
if src_type in (list, tuple):
if dst_type is list:
result[k] = [str(x) for x in value]
continue
if dst_type is tuple:
result[k] = tuple([str(x) for x in value])
continue
# in all the other cases, we are only interested in the
# first value.
value = value[0]
# Maybe we already have what is expected? Then don't change
# anything.
if src_type is dst_type:
result[k] = value
continue
if dst_type in (str, int):
try:
result[k] = dst_type(value)
except:
result[k] = default
elif dst_type is tuple:
result[k] = (value,)
elif dst_type is list:
result[k] = [value]
elif dst_type is dict:
result[k] = {0: str(value)}
else:
raise ValueError('cannot cast form into type %r' % dst_type)
result['ln'] = wash_language(result['ln'])
return result

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