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# IVLE - Informatics Virtual Learning Environment
# Copyright (C) 2007-2008 The University of Melbourne
#
# This program 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.
#
# This program 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 this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
# Module: dispatch.request
# Author: Matt Giuca
# Date: 12/12/2007
# Builds an IVLE request object from a mod_python request object.
# See design notes/apps/dispatch.txt for a full specification of this request
# object.
import common.util
import mod_python
from mod_python import (util, Session, Cookie)
import conf
class Request:
"""An IVLE request object. This is presented to the IVLE apps as a way of
interacting with the web server and the dispatcher.
Request object attributes:
method (read)
String. The request method (eg. 'GET', 'POST', etc)
uri (read)
String. The path portion of the URI.
app (read)
String. Name of the application specified in the URL, or None.
path (read)
String. The path specified in the URL *not including* the
application or the IVLE location prefix. eg. a URL of
"/ivle/files/joe/myfiles" has a path of "joe/myfiles".
user (read)
User object. Details of the user who is currently logged in, or
None.
hostname (read)
String. Hostname the server is running on.
headers_in (read)
Table object representing headers sent by the client.
headers_out (read, can be written to)
Table object representing headers to be sent to the client.
publicmode (read)
Bool. True if the request came for the "public host" as
configured in conf.py. Note that public mode requests do not
have an app (app is set to None).
status (write)
Int. Response status number. Use one of the status codes defined
in class Request.
content_type (write)
String. The Content-Type (mime type) header value.
location (write)
String. Response "Location" header value. Used with HTTP redirect
responses.
title (write)
String. HTML page title. Used if write_html_head_foot is True, in
the HTML title element text.
styles (write)
List of strings. Write a list of URLs to CSS files here, and they
will be incorporated as <link rel="stylesheet" type="text/css">
elements in the head, if write_html_head_foot is True.
URLs should be relative to the IVLE root; they will be fixed up
to be site-relative.
scripts (write)
List of strings. Write a list of URLs to JS files here, and they
will be incorporated as <script type="text/javascript"> elements
in the head, if write_html_head_foot is True.
URLs should be relative to the IVLE root; they will be fixed up
to be site-relative.
write_html_head_foot (write)
Boolean. If True, dispatch assumes that this is an XHTML page, and
will immediately write a full HTML head, open the body element,
and write heading contents to the page, before any bytes are
written. It will then write footer contents and close the body and
html elements at the end of execution.
This value should be set to true by all applications for all HTML
output (unless there is a good reason, eg. exec). The
applications should therefore output HTML content assuming that
it will be written inside the body tag. Do not write opening or
closing <html> or <body> tags.
"""
# Special code for an OK response.
# Do not use HTTP_OK; for some reason Apache produces an "OK" error
# message if you do that.
OK = 0
# HTTP status codes
HTTP_CONTINUE = 100
HTTP_SWITCHING_PROTOCOLS = 101
HTTP_PROCESSING = 102
HTTP_OK = 200
HTTP_CREATED = 201
HTTP_ACCEPTED = 202
HTTP_NON_AUTHORITATIVE = 203
HTTP_NO_CONTENT = 204
HTTP_RESET_CONTENT = 205
HTTP_PARTIAL_CONTENT = 206
HTTP_MULTI_STATUS = 207
HTTP_MULTIPLE_CHOICES = 300
HTTP_MOVED_PERMANENTLY = 301
HTTP_MOVED_TEMPORARILY = 302
HTTP_SEE_OTHER = 303
HTTP_NOT_MODIFIED = 304
HTTP_USE_PROXY = 305
HTTP_TEMPORARY_REDIRECT = 307
HTTP_BAD_REQUEST = 400
HTTP_UNAUTHORIZED = 401
HTTP_PAYMENT_REQUIRED = 402
HTTP_FORBIDDEN = 403
HTTP_NOT_FOUND = 404
HTTP_METHOD_NOT_ALLOWED = 405
HTTP_NOT_ACCEPTABLE = 406
HTTP_PROXY_AUTHENTICATION_REQUIRED= 407
HTTP_REQUEST_TIME_OUT = 408
HTTP_CONFLICT = 409
HTTP_GONE = 410
HTTP_LENGTH_REQUIRED = 411
HTTP_PRECONDITION_FAILED = 412
HTTP_REQUEST_ENTITY_TOO_LARGE = 413
HTTP_REQUEST_URI_TOO_LARGE = 414
HTTP_UNSUPPORTED_MEDIA_TYPE = 415
HTTP_RANGE_NOT_SATISFIABLE = 416
HTTP_EXPECTATION_FAILED = 417
HTTP_UNPROCESSABLE_ENTITY = 422
HTTP_LOCKED = 423
HTTP_FAILED_DEPENDENCY = 424
HTTP_INTERNAL_SERVER_ERROR = 500
HTTP_NOT_IMPLEMENTED = 501
HTTP_BAD_GATEWAY = 502
HTTP_SERVICE_UNAVAILABLE = 503
HTTP_GATEWAY_TIME_OUT = 504
HTTP_VERSION_NOT_SUPPORTED = 505
HTTP_VARIANT_ALSO_VARIES = 506
HTTP_INSUFFICIENT_STORAGE = 507
HTTP_NOT_EXTENDED = 510
def __init__(self, req, write_html_head):
"""Builds an IVLE request object from a mod_python request object.
This results in an object with all of the necessary methods and
additional fields.
req: A mod_python request object.
write_html_head: Function which is called when writing the automatic
HTML header. Accepts a single argument, the IVLE request object.
"""
# Methods are mostly wrappers around the Apache request object
self.apache_req = req
self.func_write_html_head = write_html_head
self.headers_written = False
# Determine if the browser used the public host name to make the
# request (in which case we are in "public mode")
if req.hostname == conf.public_host:
self.publicmode = True
else:
self.publicmode = False
# Inherit values for the input members
self.method = req.method
self.uri = req.uri
# Split the given path into the app (top-level dir) and sub-path
# (after first stripping away the root directory)
path = common.util.unmake_path(req.uri)
if self.publicmode:
self.app = None
self.path = path
else:
(self.app, self.path) = (common.util.split_path(path))
self.user = None
self.hostname = req.hostname
self.headers_in = req.headers_in
self.headers_out = req.headers_out
# Default values for the output members
self.status = Request.HTTP_OK
self.content_type = None # Use Apache's default
self.location = None
self.title = None # Will be set by dispatch before passing to app
self.styles = []
self.scripts = []
self.write_html_head_foot = False
self.got_common_vars = False
def __writeheaders(self):
"""Writes out the HTTP and HTML headers before any real data is
written."""
self.headers_written = True
# Prepare the HTTP and HTML headers before the first write is made
if self.content_type != None:
self.apache_req.content_type = self.content_type
self.apache_req.status = self.status
if self.location != None:
self.apache_req.headers_out['Location'] = self.location
if self.write_html_head_foot:
# Write the HTML header, pass "self" (request object)
self.func_write_html_head(self)
def ensure_headers_written(self):
"""Writes out the HTTP and HTML headers if they haven't already been
written."""
if not self.headers_written:
self.__writeheaders()
def write(self, string, flush=1):
"""Writes string directly to the client, then flushes the buffer,
unless flush is 0."""
if not self.headers_written:
self.__writeheaders()
if isinstance(string, unicode):
# Encode unicode strings as UTF-8
# (Otherwise cannot handle being written to a bytestream)
self.apache_req.write(string.encode('utf8'), flush)
else:
# 8-bit clean strings just get written directly.
# This includes binary strings.
self.apache_req.write(string, flush)
def flush(self):
"""Flushes the output buffer."""
self.apache_req.flush()
def sendfile(self, filename):
"""Sends the named file directly to the client."""
if not self.headers_written:
self.__writeheaders()
self.apache_req.sendfile(filename)
def read(self, len=None):
"""Reads at most len bytes directly from the client. (See mod_python
Request.read)."""
if len is None:
return self.apache_req.read()
else:
return self.apache_req.read(len)
def throw_error(self, httpcode, message=None):
"""Writes out an HTTP error of the specified code. Raises an exception
which is caught by the dispatch or web server, so any code following
this call will not be executed.
httpcode: An HTTP response status code. Pass a constant from the
Request class.
"""
raise common.util.IVLEError(httpcode, message)
def throw_redirect(self, location):
"""Writes out an HTTP redirect to the specified URL. Raises an
exception which is caught by the dispatch or web server, so any
code following this call will not be executed.
httpcode: An HTTP response status code. Pass a constant from the
Request class.
"""
mod_python.util.redirect(self.apache_req, location)
def add_cookie(self, cookie, value=None, **attributes):
"""Inserts a cookie into this request object's headers."""
if value is None:
Cookie.add_cookie(self.apache_req, cookie)
else:
Cookie.add_cookie(self.apache_req, cookie, value, **attributes)
def get_session(self):
"""Returns a mod_python Session object for this request.
Note that this is dependent on mod_python and may need to change
interface if porting away from mod_python."""
# Cache the session object and set the timeout to 24 hours.
if not hasattr(self, 'session'):
self.session = Session.FileSession(self.apache_req,
timeout = 60 * 60 * 24)
return self.session
def get_fieldstorage(self):
"""Returns a mod_python FieldStorage object for this request.
Note that this is dependent on mod_python and may need to change
interface if porting away from mod_python."""
# Cache the fieldstorage object
if not hasattr(self, 'fields'):
self.fields = util.FieldStorage(self.apache_req)
return self.fields
def get_cgi_environ(self):
"""Returns the CGI environment emulation for this request. (Calls
add_common_vars). The environment is returned as a mapping
compatible with os.environ."""
if not self.got_common_vars:
self.apache_req.add_common_vars()
self.got_common_vars = True
return self.apache_req.subprocess_env
@staticmethod
def get_http_codename(code):
"""Given a HTTP error code int, returns a (name, description)
pair, suitable for displaying to the user.
May return (None,None) if code is unknown.
Only lists common 4xx and 5xx codes (since this is just used
to display throw_error error messages).
"""
try:
return http_codenames[code]
except KeyError:
return None, None
# Human strings for HTTP response codes
http_codenames = {
Request.HTTP_BAD_REQUEST:
("Bad Request",
"Your browser sent a request IVLE did not understand."),
Request.HTTP_UNAUTHORIZED:
("Unauthorized",
"You are not allowed to view this part of IVLE."),
Request.HTTP_FORBIDDEN:
("Forbidden",
"You are not allowed to view this part of IVLE."),
Request.HTTP_NOT_FOUND:
("Not Found",
"The application or file you requested does not exist."),
Request.HTTP_METHOD_NOT_ALLOWED:
("Method Not Allowed",
"Your browser is interacting with IVLE in the wrong way."
"This is probably a bug in IVLE. "
"Please report it to the administrators."),
Request.HTTP_INTERNAL_SERVER_ERROR:
("Internal Server Error",
"An unknown error occured in IVLE."),
Request.HTTP_NOT_IMPLEMENTED:
("Not Implemented",
"The application or file you requested has not been implemented "
"in IVLE."),
Request.HTTP_SERVICE_UNAVAILABLE:
("Service Unavailable",
"IVLE is currently experiencing technical difficulties. "
"Please try again later."),
}
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