~azzar1/unity/add-show-desktop-key

# 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) = (common.util.split_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."),

}