authenticate local file access

adds AuthenticatedFileHandler, which extends StaticFileHandler with
a simple authentication check before providing access to files local
to the notebook dir.

IPython/frontend/html/notebook/handlers.py

@@ -1,614 +1,623 b''
 """Tornado handlers for the notebook.
 
 Authors:
 
 * Brian Granger
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import logging
 import Cookie
 import uuid
 
 from tornado import web
 from tornado import websocket
 
 from zmq.eventloop import ioloop
 from zmq.utils import jsonapi
 
 from IPython.external.decorator import decorator
 from IPython.zmq.session import Session
 from IPython.lib.security import passwd_check
 
 try:
     from docutils.core import publish_string
 except ImportError:
     publish_string = None
 
 #-----------------------------------------------------------------------------
 # Monkeypatch for Tornado <= 2.1.1 - Remove when no longer necessary!
 #-----------------------------------------------------------------------------
 
 # Google Chrome, as of release 16, changed its websocket protocol number.  The
 # parts tornado cares about haven't really changed, so it's OK to continue
 # accepting Chrome connections, but as of Tornado 2.1.1 (the currently released
 # version as of Oct 30/2011) the version check fails, see the issue report:
 
 # https://github.com/facebook/tornado/issues/385
 
 # This issue has been fixed in Tornado post 2.1.1:
 
 # https://github.com/facebook/tornado/commit/84d7b458f956727c3b0d6710
 
 # Here we manually apply the same patch as above so that users of IPython can
 # continue to work with an officially released Tornado.  We make the
 # monkeypatch version check as narrow as possible to limit its effects; once
 # Tornado 2.1.1 is no longer found in the wild we'll delete this code.
 
 import tornado
 
 if tornado.version_info <= (2,1,1):
 
     def _execute(self, transforms, *args, **kwargs):
         from tornado.websocket import WebSocketProtocol8, WebSocketProtocol76
         
         self.open_args = args
         self.open_kwargs = kwargs
 
         # The difference between version 8 and 13 is that in 8 the
         # client sends a "Sec-Websocket-Origin" header and in 13 it's
         # simply "Origin".
         if self.request.headers.get("Sec-WebSocket-Version") in ("7", "8", "13"):
             self.ws_connection = WebSocketProtocol8(self)
             self.ws_connection.accept_connection()
             
         elif self.request.headers.get("Sec-WebSocket-Version"):
             self.stream.write(tornado.escape.utf8(
                 "HTTP/1.1 426 Upgrade Required\r\n"
                 "Sec-WebSocket-Version: 8\r\n\r\n"))
             self.stream.close()
             
         else:
             self.ws_connection = WebSocketProtocol76(self)
             self.ws_connection.accept_connection()
 
     websocket.WebSocketHandler._execute = _execute
     del _execute
     
 #-----------------------------------------------------------------------------
 # Decorator for disabling read-only handlers
 #-----------------------------------------------------------------------------
 
 @decorator
 def not_if_readonly(f, self, *args, **kwargs):
     if self.application.read_only:
         raise web.HTTPError(403, "Notebook server is read-only")
     else:
         return f(self, *args, **kwargs)
 
 @decorator
 def authenticate_unless_readonly(f, self, *args, **kwargs):
     """authenticate this page *unless* readonly view is active.
     
     In read-only mode, the notebook list and print view should
     be accessible without authentication.
     """
     
     @web.authenticated
     def auth_f(self, *args, **kwargs):
         return f(self, *args, **kwargs)
+
     if self.application.read_only:
         return f(self, *args, **kwargs)
     else:
         return auth_f(self, *args, **kwargs)
 
 #-----------------------------------------------------------------------------
 # Top-level handlers
 #-----------------------------------------------------------------------------
 
 class RequestHandler(web.RequestHandler):
     """RequestHandler with default variable setting."""
 
     def render(*args, **kwargs):
         kwargs.setdefault('message', '')
         return web.RequestHandler.render(*args, **kwargs)
 
 class AuthenticatedHandler(RequestHandler):
     """A RequestHandler with an authenticated user."""
 
     def get_current_user(self):
         user_id = self.get_secure_cookie("username")
         # For now the user_id should not return empty, but it could eventually
         if user_id == '':
             user_id = 'anonymous'
         if user_id is None:
             # prevent extra Invalid cookie sig warnings:
             self.clear_cookie('username')
             if not self.application.password and not self.application.read_only:
                 user_id = 'anonymous'
         return user_id
 
     @property
     def logged_in(self):
         """Is a user currently logged in?
 
         """
         user = self.get_current_user()
         return (user and not user == 'anonymous')
 
     @property
     def login_available(self):
         """May a user proceed to log in?
 
         This returns True if login capability is available, irrespective of
         whether the user is already logged in or not.
 
         """
         return bool(self.application.password)
 
     @property
     def read_only(self):
         """Is the notebook read-only?
 
         """
         return self.application.read_only
 
     @property
     def ws_url(self):
         """websocket url matching the current request
         
         turns http[s]://host[:port] into
                 ws[s]://host[:port]
         """
         proto = self.request.protocol.replace('http', 'ws')
         return "%s://%s" % (proto, self.request.host)
 
 
+class AuthenticatedFileHandler(AuthenticatedHandler, web.StaticFileHandler):
+    """static files should only be accessible when logged in"""
+
+    @authenticate_unless_readonly
+    def get(self, path):
+        return web.StaticFileHandler.get(self, path)
+
+
 class ProjectDashboardHandler(AuthenticatedHandler):
 
     @authenticate_unless_readonly
     def get(self):
         nbm = self.application.notebook_manager
         project = nbm.notebook_dir
         self.render(
             'projectdashboard.html', project=project,
             base_project_url=u'/', base_kernel_url=u'/',
             read_only=self.read_only,
             logged_in=self.logged_in,
             login_available=self.login_available
         )
 
 
 class LoginHandler(AuthenticatedHandler):
 
     def _render(self, message=None):
         self.render('login.html',
                 next=self.get_argument('next', default='/'),
                 read_only=self.read_only,
                 logged_in=self.logged_in,
                 login_available=self.login_available,
                 message=message
         )
 
     def get(self):
         if self.current_user:
             self.redirect(self.get_argument('next', default='/'))
         else:
             self._render()
 
     def post(self):
         pwd = self.get_argument('password', default=u'')
         if self.application.password:
             if passwd_check(self.application.password, pwd):
                 self.set_secure_cookie('username', str(uuid.uuid4()))
             else:
                 self._render(message={'error': 'Invalid password'})
                 return
 
         self.redirect(self.get_argument('next', default='/'))
 
 
 class LogoutHandler(AuthenticatedHandler):
 
     def get(self):
         self.clear_cookie('username')
         if self.login_available:
             message = {'info': 'Successfully logged out.'}
         else:
             message = {'warning': 'Cannot log out.  Notebook authentication '
                        'is disabled.'}
 
         self.render('logout.html',
                     read_only=self.read_only,
                     logged_in=self.logged_in,
                     login_available=self.login_available,
                     message=message)
 
 
 class NewHandler(AuthenticatedHandler):
 
     @web.authenticated
     def get(self):
         nbm = self.application.notebook_manager
         project = nbm.notebook_dir
         notebook_id = nbm.new_notebook()
         self.render(
             'notebook.html', project=project,
             notebook_id=notebook_id,
             base_project_url=u'/', base_kernel_url=u'/',
             kill_kernel=False,
             read_only=False,
             logged_in=self.logged_in,
             login_available=self.login_available,
             mathjax_url=self.application.ipython_app.mathjax_url,
         )
 
 
 class NamedNotebookHandler(AuthenticatedHandler):
 
     @authenticate_unless_readonly
     def get(self, notebook_id):
         nbm = self.application.notebook_manager
         project = nbm.notebook_dir
         if not nbm.notebook_exists(notebook_id):
             raise web.HTTPError(404, u'Notebook does not exist: %s' % notebook_id)
         
         self.render(
             'notebook.html', project=project,
             notebook_id=notebook_id,
             base_project_url=u'/', base_kernel_url=u'/',
             kill_kernel=False,
             read_only=self.read_only,
             logged_in=self.logged_in,
             login_available=self.login_available,
             mathjax_url=self.application.ipython_app.mathjax_url,
         )
 
 
 #-----------------------------------------------------------------------------
 # Kernel handlers
 #-----------------------------------------------------------------------------
 
 
 class MainKernelHandler(AuthenticatedHandler):
 
     @web.authenticated
     def get(self):
         km = self.application.kernel_manager
         self.finish(jsonapi.dumps(km.kernel_ids))
 
     @web.authenticated
     def post(self):
         km = self.application.kernel_manager
         notebook_id = self.get_argument('notebook', default=None)
         kernel_id = km.start_kernel(notebook_id)
         data = {'ws_url':self.ws_url,'kernel_id':kernel_id}
         self.set_header('Location', '/'+kernel_id)
         self.finish(jsonapi.dumps(data))
 
 
 class KernelHandler(AuthenticatedHandler):
 
     SUPPORTED_METHODS = ('DELETE')
 
     @web.authenticated
     def delete(self, kernel_id):
         km = self.application.kernel_manager
         km.kill_kernel(kernel_id)
         self.set_status(204)
         self.finish()
 
 
 class KernelActionHandler(AuthenticatedHandler):
 
     @web.authenticated
     def post(self, kernel_id, action):
         km = self.application.kernel_manager
         if action == 'interrupt':
             km.interrupt_kernel(kernel_id)
             self.set_status(204)
         if action == 'restart':
             new_kernel_id = km.restart_kernel(kernel_id)
             data = {'ws_url':self.ws_url,'kernel_id':new_kernel_id}
             self.set_header('Location', '/'+new_kernel_id)
             self.write(jsonapi.dumps(data))
         self.finish()
 
 
 class ZMQStreamHandler(websocket.WebSocketHandler):
 
     def _reserialize_reply(self, msg_list):
         """Reserialize a reply message using JSON.
 
         This takes the msg list from the ZMQ socket, unserializes it using
         self.session and then serializes the result using JSON. This method
         should be used by self._on_zmq_reply to build messages that can
         be sent back to the browser.
         """
         idents, msg_list = self.session.feed_identities(msg_list)
         msg = self.session.unserialize(msg_list)
         try:
             msg['header'].pop('date')
         except KeyError:
             pass
         try:
             msg['parent_header'].pop('date')
         except KeyError:
             pass
         msg.pop('buffers')
         return jsonapi.dumps(msg)
 
     def _on_zmq_reply(self, msg_list):
         try:
             msg = self._reserialize_reply(msg_list)
         except:
             self.application.log.critical("Malformed message: %r" % msg_list)
         else:
             self.write_message(msg)
 
 
 class AuthenticatedZMQStreamHandler(ZMQStreamHandler):
 
     def open(self, kernel_id):
         self.kernel_id = kernel_id.decode('ascii')
         try:
             cfg = self.application.ipython_app.config
         except AttributeError:
             # protect from the case where this is run from something other than
             # the notebook app:
             cfg = None
         self.session = Session(config=cfg)
         self.save_on_message = self.on_message
         self.on_message = self.on_first_message
 
     def get_current_user(self):
         user_id = self.get_secure_cookie("username")
         if user_id == '' or (user_id is None and not self.application.password):
             user_id = 'anonymous'
         return user_id
 
     def _inject_cookie_message(self, msg):
         """Inject the first message, which is the document cookie,
         for authentication."""
         if isinstance(msg, unicode):
             # Cookie can't constructor doesn't accept unicode strings for some reason
             msg = msg.encode('utf8', 'replace')
         try:
             self.request._cookies = Cookie.SimpleCookie(msg)
         except:
             logging.warn("couldn't parse cookie string: %s",msg, exc_info=True)
 
     def on_first_message(self, msg):
         self._inject_cookie_message(msg)
         if self.get_current_user() is None:
             logging.warn("Couldn't authenticate WebSocket connection")
             raise web.HTTPError(403)
         self.on_message = self.save_on_message
 
 
 class IOPubHandler(AuthenticatedZMQStreamHandler):
 
     def initialize(self, *args, **kwargs):
         self._kernel_alive = True
         self._beating = False
         self.iopub_stream = None
         self.hb_stream = None
 
     def on_first_message(self, msg):
         try:
             super(IOPubHandler, self).on_first_message(msg)
         except web.HTTPError:
             self.close()
             return
         km = self.application.kernel_manager
         self.time_to_dead = km.time_to_dead
         kernel_id = self.kernel_id
         try:
             self.iopub_stream = km.create_iopub_stream(kernel_id)
             self.hb_stream = km.create_hb_stream(kernel_id)
         except web.HTTPError:
             # WebSockets don't response to traditional error codes so we
             # close the connection.
             if not self.stream.closed():
                 self.stream.close()
             self.close()
         else:
             self.iopub_stream.on_recv(self._on_zmq_reply)
             self.start_hb(self.kernel_died)
 
     def on_message(self, msg):
         pass
 
     def on_close(self):
         # This method can be called twice, once by self.kernel_died and once
         # from the WebSocket close event. If the WebSocket connection is
         # closed before the ZMQ streams are setup, they could be None.
         self.stop_hb()
         if self.iopub_stream is not None and not self.iopub_stream.closed():
             self.iopub_stream.on_recv(None)
             self.iopub_stream.close()
         if self.hb_stream is not None and not self.hb_stream.closed():
             self.hb_stream.close()
 
     def start_hb(self, callback):
         """Start the heartbeating and call the callback if the kernel dies."""
         if not self._beating:
             self._kernel_alive = True
 
             def ping_or_dead():
                 if self._kernel_alive:
                     self._kernel_alive = False
                     self.hb_stream.send(b'ping')
                 else:
                     try:
                         callback()
                     except:
                         pass
                     finally:
                         self._hb_periodic_callback.stop()
 
             def beat_received(msg):
                 self._kernel_alive = True
 
             self.hb_stream.on_recv(beat_received)
             self._hb_periodic_callback = ioloop.PeriodicCallback(ping_or_dead, self.time_to_dead*1000)
             self._hb_periodic_callback.start()
             self._beating= True
 
     def stop_hb(self):
         """Stop the heartbeating and cancel all related callbacks."""
         if self._beating:
             self._hb_periodic_callback.stop()
             if not self.hb_stream.closed():
                 self.hb_stream.on_recv(None)
 
     def kernel_died(self):
         self.application.kernel_manager.delete_mapping_for_kernel(self.kernel_id)
         self.write_message(
             {'header': {'msg_type': 'status'},
              'parent_header': {},
              'content': {'execution_state':'dead'}
             }
         )
         self.on_close()
 
 
 class ShellHandler(AuthenticatedZMQStreamHandler):
 
     def initialize(self, *args, **kwargs):
         self.shell_stream = None
 
     def on_first_message(self, msg):
         try:
             super(ShellHandler, self).on_first_message(msg)
         except web.HTTPError:
             self.close()
             return
         km = self.application.kernel_manager
         self.max_msg_size = km.max_msg_size
         kernel_id = self.kernel_id
         try:
             self.shell_stream = km.create_shell_stream(kernel_id)
         except web.HTTPError:
             # WebSockets don't response to traditional error codes so we
             # close the connection.
             if not self.stream.closed():
                 self.stream.close()
             self.close()
         else:
             self.shell_stream.on_recv(self._on_zmq_reply)
 
     def on_message(self, msg):
         if len(msg) < self.max_msg_size:
             msg = jsonapi.loads(msg)
             self.session.send(self.shell_stream, msg)
 
     def on_close(self):
         # Make sure the stream exists and is not already closed.
         if self.shell_stream is not None and not self.shell_stream.closed():
             self.shell_stream.close()
 
 
 #-----------------------------------------------------------------------------
 # Notebook web service handlers
 #-----------------------------------------------------------------------------
 
 class NotebookRootHandler(AuthenticatedHandler):
 
     @authenticate_unless_readonly
     def get(self):
         
         nbm = self.application.notebook_manager
         files = nbm.list_notebooks()
         self.finish(jsonapi.dumps(files))
 
     @web.authenticated
     def post(self):
         nbm = self.application.notebook_manager
         body = self.request.body.strip()
         format = self.get_argument('format', default='json')
         name = self.get_argument('name', default=None)
         if body:
             notebook_id = nbm.save_new_notebook(body, name=name, format=format)
         else:
             notebook_id = nbm.new_notebook()
         self.set_header('Location', '/'+notebook_id)
         self.finish(jsonapi.dumps(notebook_id))
 
 
 class NotebookHandler(AuthenticatedHandler):
 
     SUPPORTED_METHODS = ('GET', 'PUT', 'DELETE')
 
     @authenticate_unless_readonly
     def get(self, notebook_id):
         nbm = self.application.notebook_manager
         format = self.get_argument('format', default='json')
         last_mod, name, data = nbm.get_notebook(notebook_id, format)
         
         if format == u'json':
             self.set_header('Content-Type', 'application/json')
             self.set_header('Content-Disposition','attachment; filename="%s.ipynb"' % name)
         elif format == u'py':
             self.set_header('Content-Type', 'application/x-python')
             self.set_header('Content-Disposition','attachment; filename="%s.py"' % name)
         self.set_header('Last-Modified', last_mod)
         self.finish(data)
 
     @web.authenticated
     def put(self, notebook_id):
         nbm = self.application.notebook_manager
         format = self.get_argument('format', default='json')
         name = self.get_argument('name', default=None)
         nbm.save_notebook(notebook_id, self.request.body, name=name, format=format)
         self.set_status(204)
         self.finish()
 
     @web.authenticated
     def delete(self, notebook_id):
         nbm = self.application.notebook_manager
         nbm.delete_notebook(notebook_id)
         self.set_status(204)
         self.finish()
 
 #-----------------------------------------------------------------------------
 # RST web service handlers
 #-----------------------------------------------------------------------------
 
 
 class RSTHandler(AuthenticatedHandler):
 
     @web.authenticated
     def post(self):
         if publish_string is None:
             raise web.HTTPError(503, u'docutils not available')
         body = self.request.body.strip()
         source = body
         # template_path=os.path.join(os.path.dirname(__file__), u'templates', u'rst_template.html')
         defaults = {'file_insertion_enabled': 0,
                     'raw_enabled': 0,
                     '_disable_config': 1,
                     'stylesheet_path': 0
                     # 'template': template_path
         }
         try:
             html = publish_string(source, writer_name='html',
                                   settings_overrides=defaults
             )
         except:
             raise web.HTTPError(400, u'Invalid RST')
         print html
         self.set_header('Content-Type', 'text/html')
         self.finish(html)
 
 

IPython/frontend/html/notebook/notebookapp.py

@@ -1,386 +1,387 b''
 """A tornado based IPython notebook server.
 
 Authors:
 
 * Brian Granger
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 # stdlib
 import errno
 import logging
 import os
 import signal
 import socket
 import sys
 import threading
 import webbrowser
 
 # Third party
 import zmq
 
 # Install the pyzmq ioloop. This has to be done before anything else from
 # tornado is imported.
 from zmq.eventloop import ioloop
 # FIXME: ioloop.install is new in pyzmq-2.1.7, so remove this conditional
 # when pyzmq dependency is updated beyond that.
 if hasattr(ioloop, 'install'):
     ioloop.install()
 else:
     import tornado.ioloop
     tornado.ioloop.IOLoop = ioloop.IOLoop
 
 from tornado import httpserver
 from tornado import web
 
 # Our own libraries
 from .kernelmanager import MappingKernelManager
 from .handlers import (LoginHandler, LogoutHandler,
     ProjectDashboardHandler, NewHandler, NamedNotebookHandler,
     MainKernelHandler, KernelHandler, KernelActionHandler, IOPubHandler,
-    ShellHandler, NotebookRootHandler, NotebookHandler, RSTHandler
+    ShellHandler, NotebookRootHandler, NotebookHandler, RSTHandler,
+    AuthenticatedFileHandler,
 )
 from .notebookmanager import NotebookManager
 
 from IPython.config.application import catch_config_error, boolean_flag
 from IPython.core.application import BaseIPythonApplication
 from IPython.core.profiledir import ProfileDir
 from IPython.lib.kernel import swallow_argv
 from IPython.zmq.session import Session, default_secure
 from IPython.zmq.zmqshell import ZMQInteractiveShell
 from IPython.zmq.ipkernel import (
     flags as ipkernel_flags,
     aliases as ipkernel_aliases,
     IPKernelApp
 )
 from IPython.utils.traitlets import Dict, Unicode, Integer, List, Enum, Bool
 
 #-----------------------------------------------------------------------------
 # Module globals
 #-----------------------------------------------------------------------------
 
 _kernel_id_regex = r"(?P<kernel_id>\w+-\w+-\w+-\w+-\w+)"
 _kernel_action_regex = r"(?P<action>restart|interrupt)"
 _notebook_id_regex = r"(?P<notebook_id>\w+-\w+-\w+-\w+-\w+)"
 
 LOCALHOST = '127.0.0.1'
 
 _examples = """
 ipython notebook                       # start the notebook
 ipython notebook --profile=sympy       # use the sympy profile
 ipython notebook --pylab=inline        # pylab in inline plotting mode
 ipython notebook --certfile=mycert.pem # use SSL/TLS certificate
 ipython notebook --port=5555 --ip=*    # Listen on port 5555, all interfaces
 """
 
 #-----------------------------------------------------------------------------
 # The Tornado web application
 #-----------------------------------------------------------------------------
 
 class NotebookWebApplication(web.Application):
 
     def __init__(self, ipython_app, kernel_manager, notebook_manager, log, settings_overrides):
         handlers = [
             (r"/", ProjectDashboardHandler),
             (r"/login", LoginHandler),
             (r"/logout", LogoutHandler),
             (r"/new", NewHandler),
             (r"/%s" % _notebook_id_regex, NamedNotebookHandler),
             (r"/kernels", MainKernelHandler),
             (r"/kernels/%s" % _kernel_id_regex, KernelHandler),
             (r"/kernels/%s/%s" % (_kernel_id_regex, _kernel_action_regex), KernelActionHandler),
             (r"/kernels/%s/iopub" % _kernel_id_regex, IOPubHandler),
             (r"/kernels/%s/shell" % _kernel_id_regex, ShellHandler),
             (r"/notebooks", NotebookRootHandler),
             (r"/notebooks/%s" % _notebook_id_regex, NotebookHandler),
             (r"/rstservice/render", RSTHandler),
-            (r"/local/(.*)", web.StaticFileHandler, {'path' : notebook_manager.notebook_dir}),
+            (r"/local/(.*)", AuthenticatedFileHandler, {'path' : notebook_manager.notebook_dir}),
         ]
         settings = dict(
             template_path=os.path.join(os.path.dirname(__file__), "templates"),
             static_path=os.path.join(os.path.dirname(__file__), "static"),
             cookie_secret=os.urandom(1024),
             login_url="/login",
         )
 
         # allow custom overrides for the tornado web app.
         settings.update(settings_overrides)
 
         super(NotebookWebApplication, self).__init__(handlers, **settings)
 
         self.kernel_manager = kernel_manager
         self.log = log
         self.notebook_manager = notebook_manager
         self.ipython_app = ipython_app
         self.read_only = self.ipython_app.read_only
 
 
 #-----------------------------------------------------------------------------
 # Aliases and Flags
 #-----------------------------------------------------------------------------
 
 flags = dict(ipkernel_flags)
 flags['no-browser']=(
     {'NotebookApp' : {'open_browser' : False}},
     "Don't open the notebook in a browser after startup."
 )
 flags['no-mathjax']=(
     {'NotebookApp' : {'enable_mathjax' : False}},
     """Disable MathJax
     
     MathJax is the javascript library IPython uses to render math/LaTeX. It is
     very large, so you may want to disable it if you have a slow internet
     connection, or for offline use of the notebook.
     
     When disabled, equations etc. will appear as their untransformed TeX source.
     """
 )
 flags['read-only'] = (
     {'NotebookApp' : {'read_only' : True}},
     """Allow read-only access to notebooks.
     
     When using a password to protect the notebook server, this flag
     allows unauthenticated clients to view the notebook list, and
     individual notebooks, but not edit them, start kernels, or run
     code.
     
     If no password is set, the server will be entirely read-only.
     """
 )
 
 # Add notebook manager flags
 flags.update(boolean_flag('script', 'NotebookManager.save_script',
                'Auto-save a .py script everytime the .ipynb notebook is saved',
                'Do not auto-save .py scripts for every notebook'))
 
 # the flags that are specific to the frontend
 # these must be scrubbed before being passed to the kernel,
 # or it will raise an error on unrecognized flags
 notebook_flags = ['no-browser', 'no-mathjax', 'read-only', 'script', 'no-script']
 
 aliases = dict(ipkernel_aliases)
 
 aliases.update({
     'ip': 'NotebookApp.ip',
     'port': 'NotebookApp.port',
     'keyfile': 'NotebookApp.keyfile',
     'certfile': 'NotebookApp.certfile',
     'notebook-dir': 'NotebookManager.notebook_dir',
 })
 
 # remove ipkernel flags that are singletons, and don't make sense in
 # multi-kernel evironment:
 aliases.pop('f', None)
 
 notebook_aliases = [u'port', u'ip', u'keyfile', u'certfile',
                     u'notebook-dir']
 
 #-----------------------------------------------------------------------------
 # NotebookApp
 #-----------------------------------------------------------------------------
 
 class NotebookApp(BaseIPythonApplication):
 
     name = 'ipython-notebook'
     default_config_file_name='ipython_notebook_config.py'
     
     description = """
         The IPython HTML Notebook.
         
         This launches a Tornado based HTML Notebook Server that serves up an
         HTML5/Javascript Notebook client.
     """
     examples = _examples
     
     classes = [IPKernelApp, ZMQInteractiveShell, ProfileDir, Session,
                MappingKernelManager, NotebookManager]
     flags = Dict(flags)
     aliases = Dict(aliases)
 
     kernel_argv = List(Unicode)
 
     log_level = Enum((0,10,20,30,40,50,'DEBUG','INFO','WARN','ERROR','CRITICAL'),
                     default_value=logging.INFO,
                     config=True,
                     help="Set the log level by value or name.")
 
     # Network related information.
 
     ip = Unicode(LOCALHOST, config=True,
         help="The IP address the notebook server will listen on."
     )
 
     def _ip_changed(self, name, old, new):
         if new == u'*': self.ip = u''
 
     port = Integer(8888, config=True,
         help="The port the notebook server will listen on."
     )
 
     certfile = Unicode(u'', config=True, 
         help="""The full path to an SSL/TLS certificate file."""
     )
     
     keyfile = Unicode(u'', config=True, 
         help="""The full path to a private key file for usage with SSL/TLS."""
     )
 
     password = Unicode(u'', config=True,
                       help="""Hashed password to use for web authentication.
 
                       To generate, type in a python/IPython shell:
 
                         from IPython.lib import passwd; passwd()
 
                       The string should be of the form type:salt:hashed-password.
                       """
     )
     
     open_browser = Bool(True, config=True,
                         help="Whether to open in a browser after starting.")
     
     read_only = Bool(False, config=True,
         help="Whether to prevent editing/execution of notebooks."
     )
     
     webapp_settings = Dict(config=True,
             help="Supply overrides for the tornado.web.Application that the "
                  "IPython notebook uses.")
     
     enable_mathjax = Bool(True, config=True,
         help="""Whether to enable MathJax for typesetting math/TeX
 
         MathJax is the javascript library IPython uses to render math/LaTeX. It is
         very large, so you may want to disable it if you have a slow internet
         connection, or for offline use of the notebook.
 
         When disabled, equations etc. will appear as their untransformed TeX source.
         """
     )
     def _enable_mathjax_changed(self, name, old, new):
         """set mathjax url to empty if mathjax is disabled"""
         if not new:
             self.mathjax_url = u''
     
     mathjax_url = Unicode("", config=True,
         help="""The url for MathJax.js."""
     )
     def _mathjax_url_default(self):
         if not self.enable_mathjax:
             return u''
         static_path = self.webapp_settings.get("static_path", os.path.join(os.path.dirname(__file__), "static"))
         if os.path.exists(os.path.join(static_path, 'mathjax', "MathJax.js")):
             self.log.info("Using local MathJax")
             return u"static/mathjax/MathJax.js"
         else:
             self.log.info("Using MathJax from CDN")
             return u"http://cdn.mathjax.org/mathjax/latest/MathJax.js"
     
     def _mathjax_url_changed(self, name, old, new):
         if new and not self.enable_mathjax:
             # enable_mathjax=False overrides mathjax_url
             self.mathjax_url = u''
         else:
             self.log.info("Using MathJax: %s", new)
 
     def parse_command_line(self, argv=None):
         super(NotebookApp, self).parse_command_line(argv)
         if argv is None:
             argv = sys.argv[1:]
 
         # Scrub frontend-specific flags
         self.kernel_argv = swallow_argv(argv, notebook_aliases, notebook_flags)
         # Kernel should inherit default config file from frontend
         self.kernel_argv.append("--KernelApp.parent_appname='%s'"%self.name)
 
     def init_configurables(self):
         # Don't let Qt or ZMQ swallow KeyboardInterupts.
         signal.signal(signal.SIGINT, signal.SIG_DFL)
 
         # force Session default to be secure
         default_secure(self.config)
         # Create a KernelManager and start a kernel.
         self.kernel_manager = MappingKernelManager(
             config=self.config, log=self.log, kernel_argv=self.kernel_argv,
             connection_dir = self.profile_dir.security_dir,
         )
         self.notebook_manager = NotebookManager(config=self.config, log=self.log)
         self.notebook_manager.list_notebooks()
 
     def init_logging(self):
         super(NotebookApp, self).init_logging()
         # This prevents double log messages because tornado use a root logger that
         # self.log is a child of. The logging module dipatches log messages to a log
         # and all of its ancenstors until propagate is set to False.
         self.log.propagate = False
 
     @catch_config_error
     def initialize(self, argv=None):
         super(NotebookApp, self).initialize(argv)
         self.init_configurables()
         self.web_app = NotebookWebApplication(
             self, self.kernel_manager, self.notebook_manager, self.log,
             self.webapp_settings
         )
         if self.certfile:
             ssl_options = dict(certfile=self.certfile)
             if self.keyfile:
                 ssl_options['keyfile'] = self.keyfile
         else:
             ssl_options = None
         self.web_app.password = self.password
         self.http_server = httpserver.HTTPServer(self.web_app, ssl_options=ssl_options)
         if ssl_options is None and not self.ip:
             self.log.critical('WARNING: the notebook server is listening on all IP addresses '
                               'but not using any encryption or authentication. This is highly '
                               'insecure and not recommended.')
 
         # Try random ports centered around the default.
         from random import randint
         n = 50  # Max number of attempts, keep reasonably large.
         for port in range(self.port, self.port+5) + [self.port + randint(-2*n, 2*n) for i in range(n-5)]:
             try:
                 self.http_server.listen(port, self.ip)
             except socket.error, e:
                 if e.errno != errno.EADDRINUSE:
                     raise
                 self.log.info('The port %i is already in use, trying another random port.' % port)
             else:
                 self.port = port
                 break
 
     def start(self):
         ip = self.ip if self.ip else '[all ip addresses on your system]'
         proto = 'https' if self.certfile else 'http'
         info = self.log.info
         info("The IPython Notebook is running at: %s://%s:%i" % 
              (proto, ip, self.port) )
         info("Use Control-C to stop this server and shut down all kernels.")
 
         if self.open_browser:
             ip = self.ip or '127.0.0.1'
             b = lambda : webbrowser.open("%s://%s:%i" % (proto, ip, self.port),
                                          new=2)
             threading.Thread(target=b).start()
 
         ioloop.IOLoop.instance().start()
 
 #-----------------------------------------------------------------------------
 # Main entry point
 #-----------------------------------------------------------------------------
 
 def launch_new_instance():
     app = NotebookApp()
     app.initialize()
     app.start()