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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: cgirequest
# Author: Matt Giuca
# Date: 5/2/2007
# Presents a CGIRequest class which creates an object compatible with IVLE
# Request objects (the same interface exposed by www.dispatch.request) from a
# CGI script.
# This allows CGI scripts to create request objects and then pass them to
# normal IVLE handlers.
import sys
import os
import cgi
import urllib
import traceback
import ivle.conf
import ivle.util
# Utility functions
def _http_headers_in_from_cgi():
"""Returns a dictionary of HTTP headers and their values, reading from the
CGI environment."""
d = {}
for k in os.environ.keys():
if k.startswith("HTTP_"):
# Change the case - underscores become - and each word is
# capitalised
varname = '-'.join(map(lambda x: x[0:1] + x[1:].lower(),
k[5:].split('_')))
d[varname] = os.environ[k]
return d
class CGIRequest:
"""An IVLE request object, built from a CGI script. This is presented to
the IVLE apps as a way of interacting with the CGI server.
See dispatch.request for a full interface specification.
"""
# COPIED from dispatch/request.py
# 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):
"""Builds an CGI Request object from the current CGI environment.
This results in an object with all of the necessary methods and
additional fields.
"""
self.headers_written = False
if ('SERVER_NAME' not in os.environ or
'REQUEST_METHOD' not in os.environ or
'SCRIPT_NAME' not in os.environ or
'PATH_INFO' not in os.environ):
raise Exception("No CGI environment found")
# Determine if the browser used the public host name to make the
# request (in which case we are in "public mode")
if os.environ['SERVER_NAME'] == ivle.conf.public_host:
self.publicmode = True
else:
self.publicmode = False
# Inherit values for the input members
self.method = os.environ['REQUEST_METHOD']
self.uri = os.environ['SCRIPT_NAME'] + os.environ['PATH_INFO']
# Split the given path into the app (top-level dir) and sub-path
# (after first stripping away the root directory)
path = ivle.util.unmake_path(self.uri)
if self.publicmode:
self.app = None
(_, self.path) = (ivle.util.split_path(path))
else:
(self.app, self.path) = (ivle.util.split_path(path))
self.user = None
self.hostname = os.environ['SERVER_NAME']
self.headers_in = _http_headers_in_from_cgi()
self.headers_out = {}
# Default values for the output members
self.status = CGIRequest.HTTP_OK
self.content_type = None # Use Apache's default
self.location = None
self.styles = []
self.scripts = []
self.got_common_vars = False
def install_error_handler(self):
'''Install our exception handler as the default.'''
sys.excepthook = self.handle_unknown_exception
def __writeheaders(self):
"""Writes out the HTTP and HTML headers before any real data is
written."""
self.headers_written = True
if 'Content-Type' in self.headers_out:
self.content_type = self.headers_out['Content-Type']
if 'Location' in self.headers_out:
self.location = self.headers_out['Location']
# CGI allows for four response types: Document, Local Redirect, Client
# Redirect, and Client Redirect w/ Document
# XXX We do not allow Local Redirect
if self.location != None:
# This is a Client Redirect
print "Location: %s" % self.location
if self.content_type == None:
# Just redirect
return
# Else: This is a Client Redirect with Document
print "Status: %d" % self.status
print "Content-Type: %s" % self.content_type
else:
# This is a Document response
print "Content-Type: %s" % self.content_type
print "Status: %d" % self.status
# Print the other headers
for k,v in self.headers_out.items():
if k != 'Content-Type' and k != 'Location':
print "%s: %s" % (k, v)
# Print a blank line to signal the start of output
print
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)
sys.stdout.write(string.encode('utf8'))
else:
# 8-bit clean strings just get written directly.
# This includes binary strings.
sys.stdout.write(string)
def flush(self):
"""Flushes the output buffer."""
sys.stdout.flush()
def sendfile(self, filename):
"""Sends the named file directly to the client."""
if not self.headers_written:
self.__writeheaders()
f = open(filename)
buf = f.read(1024)
while len(buf) > 0:
sys.stdout.write(buf)
sys.stdout.flush()
buf = f.read(1024)
f.close()
def read(self, len=None):
"""Reads at most len bytes directly from the client. (See mod_python
Request.read)."""
if len is None:
return sys.stdin.read()
else:
return sys.stdin.read(len)
def handle_unknown_exception(self, exc_type, exc_value, exc_tb):
if exc_type is ivle.util.IVLEError:
self.headers_out['X-IVLE-Error-Code'] = exc_value.httpcode
self.headers_out['X-IVLE-Error-Type'] = exc_type.__name__
try:
self.headers_out['X-IVLE-Error-Message'] = exc_value.message
except AttributeError:
pass
self.headers_out['X-IVLE-Error-Info'] = urllib.quote(''.join(
traceback.format_exception(exc_type, exc_value, exc_tb)))
self.status = 500
self.ensure_headers_written()
self.write('An internal IVLE error has occurred.')
self.flush()
sys.exit(self.status)
def throw_redirect(self, location):
"""Writes out an HTTP redirect to the specified URL. Exits the
process, so any code following this call will not be executed.
httpcode: An HTTP response status code. Pass a constant from the
Request class.
"""
self.status = CGIRequest.HTTP_MOVED_TEMPORARILY
self.location = location
self.ensure_headers_written()
self.flush()
sys.exit(self.status)
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
if not hasattr(self, 'session'):
#self.session = Session.FileSession(self.apache_req)
self.session = None
# FIXME: How to get session?
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 = cgi.FieldStorage()
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."""
return os.environ
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