set no-cache header in StaticFileHandlers

rely on 304 Not Modified for caching content

IPython/html/base/handlers.py

@@ -1,486 +1,498 b''
 """Base Tornado handlers for the notebook server."""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 import functools
 import json
 import logging
 import os
 import re
 import sys
 import traceback
 try:
     # py3
     from http.client import responses
 except ImportError:
     from httplib import responses
 
 from jinja2 import TemplateNotFound
 from tornado import web
 
 try:
     from tornado.log import app_log
 except ImportError:
     app_log = logging.getLogger()
 
 import IPython
 from IPython.utils.sysinfo import get_sys_info
 
 from IPython.config import Application
 from IPython.utils.path import filefind
 from IPython.utils.py3compat import string_types
 from IPython.html.utils import is_hidden, url_path_join, url_escape
 
 #-----------------------------------------------------------------------------
 # Top-level handlers
 #-----------------------------------------------------------------------------
 non_alphanum = re.compile(r'[^A-Za-z0-9]')
 
 sys_info = json.dumps(get_sys_info())
 
 class AuthenticatedHandler(web.RequestHandler):
     """A RequestHandler with an authenticated user."""
 
     def set_default_headers(self):
         headers = self.settings.get('headers', {})
 
         if "X-Frame-Options" not in headers:
             headers["X-Frame-Options"] = "SAMEORIGIN"
 
         for header_name,value in headers.items() :
             try:
                 self.set_header(header_name, value)
             except Exception:
                 # tornado raise Exception (not a subclass)
                 # if method is unsupported (websocket and Access-Control-Allow-Origin
                 # for example, so just ignore)
                 pass
     
     def clear_login_cookie(self):
         self.clear_cookie(self.cookie_name)
     
     def get_current_user(self):
         user_id = self.get_secure_cookie(self.cookie_name)
         # 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_login_cookie()
             if not self.login_available:
                 user_id = 'anonymous'
         return user_id
 
     @property
     def cookie_name(self):
         default_cookie_name = non_alphanum.sub('-', 'username-{}'.format(
             self.request.host
         ))
         return self.settings.get('cookie_name', default_cookie_name)
     
     @property
     def password(self):
         """our password"""
         return self.settings.get('password', '')
     
     @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.settings.get('password', ''))
 
 
 class IPythonHandler(AuthenticatedHandler):
     """IPython-specific extensions to authenticated handling
     
     Mostly property shortcuts to IPython-specific settings.
     """
     
     @property
     def config(self):
         return self.settings.get('config', None)
     
     @property
     def log(self):
         """use the IPython log by default, falling back on tornado's logger"""
         if Application.initialized():
             return Application.instance().log
         else:
             return app_log
 
     @property
     def profile_dir(self):
         return self.settings.get('profile_dir', '')
     
     #---------------------------------------------------------------
     # URLs
     #---------------------------------------------------------------
     
     @property
     def mathjax_url(self):
         return self.settings.get('mathjax_url', '')
     
     @property
     def base_url(self):
         return self.settings.get('base_url', '/')
 
     @property
     def ws_url(self):
         return self.settings.get('websocket_url', '')
 
     @property
     def contents_js_source(self):
         self.log.debug("Using contents: %s", self.settings.get('contents_js_source',
             'services/contents'))
         return self.settings.get('contents_js_source', 'services/contents')
     
     #---------------------------------------------------------------
     # Manager objects
     #---------------------------------------------------------------
     
     @property
     def kernel_manager(self):
         return self.settings['kernel_manager']
 
     @property
     def contents_manager(self):
         return self.settings['contents_manager']
     
     @property
     def cluster_manager(self):
         return self.settings['cluster_manager']
     
     @property
     def session_manager(self):
         return self.settings['session_manager']
     
     @property
     def terminal_manager(self):
         return self.settings['terminal_manager']
     
     @property
     def kernel_spec_manager(self):
         return self.settings['kernel_spec_manager']
 
     #---------------------------------------------------------------
     # CORS
     #---------------------------------------------------------------
     
     @property
     def allow_origin(self):
         """Normal Access-Control-Allow-Origin"""
         return self.settings.get('allow_origin', '')
     
     @property
     def allow_origin_pat(self):
         """Regular expression version of allow_origin"""
         return self.settings.get('allow_origin_pat', None)
     
     @property
     def allow_credentials(self):
         """Whether to set Access-Control-Allow-Credentials"""
         return self.settings.get('allow_credentials', False)
     
     def set_default_headers(self):
         """Add CORS headers, if defined"""
         super(IPythonHandler, self).set_default_headers()
         if self.allow_origin:
             self.set_header("Access-Control-Allow-Origin", self.allow_origin)
         elif self.allow_origin_pat:
             origin = self.get_origin()
             if origin and self.allow_origin_pat.match(origin):
                 self.set_header("Access-Control-Allow-Origin", origin)
         if self.allow_credentials:
             self.set_header("Access-Control-Allow-Credentials", 'true')
     
     def get_origin(self):
         # Handle WebSocket Origin naming convention differences
         # 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 "Origin" in self.request.headers:
             origin = self.request.headers.get("Origin")
         else:
             origin = self.request.headers.get("Sec-Websocket-Origin", None)
         return origin
     
     #---------------------------------------------------------------
     # template rendering
     #---------------------------------------------------------------
     
     def get_template(self, name):
         """Return the jinja template object for a given name"""
         return self.settings['jinja2_env'].get_template(name)
     
     def render_template(self, name, **ns):
         ns.update(self.template_namespace)
         template = self.get_template(name)
         return template.render(**ns)
     
     @property
     def template_namespace(self):
         return dict(
             base_url=self.base_url,
             ws_url=self.ws_url,
             logged_in=self.logged_in,
             login_available=self.login_available,
             static_url=self.static_url,
             sys_info=sys_info,
             contents_js_source=self.contents_js_source,
         )
     
     def get_json_body(self):
         """Return the body of the request as JSON data."""
         if not self.request.body:
             return None
         # Do we need to call body.decode('utf-8') here?
         body = self.request.body.strip().decode(u'utf-8')
         try:
             model = json.loads(body)
         except Exception:
             self.log.debug("Bad JSON: %r", body)
             self.log.error("Couldn't parse JSON", exc_info=True)
             raise web.HTTPError(400, u'Invalid JSON in body of request')
         return model
 
     def write_error(self, status_code, **kwargs):
         """render custom error pages"""
         exc_info = kwargs.get('exc_info')
         message = ''
         status_message = responses.get(status_code, 'Unknown HTTP Error')
         if exc_info:
             exception = exc_info[1]
             # get the custom message, if defined
             try:
                 message = exception.log_message % exception.args
             except Exception:
                 pass
             
             # construct the custom reason, if defined
             reason = getattr(exception, 'reason', '')
             if reason:
                 status_message = reason
         
         # build template namespace
         ns = dict(
             status_code=status_code,
             status_message=status_message,
             message=message,
             exception=exception,
         )
         
         self.set_header('Content-Type', 'text/html')
         # render the template
         try:
             html = self.render_template('%s.html' % status_code, **ns)
         except TemplateNotFound:
             self.log.debug("No template for %d", status_code)
             html = self.render_template('error.html', **ns)
         
         self.write(html)
         
 
 
 class Template404(IPythonHandler):
     """Render our 404 template"""
     def prepare(self):
         raise web.HTTPError(404)
 
 
 class AuthenticatedFileHandler(IPythonHandler, web.StaticFileHandler):
     """static files should only be accessible when logged in"""
 
     @web.authenticated
     def get(self, path):
         if os.path.splitext(path)[1] == '.ipynb':
             name = path.rsplit('/', 1)[-1]
             self.set_header('Content-Type', 'application/json')
             self.set_header('Content-Disposition','attachment; filename="%s"' % name)
         
         return web.StaticFileHandler.get(self, path)
     
+    def set_headers(self):
+        super(AuthenticatedFileHandler, self).set_headers()
+        # disable browser caching, rely in 304 replies for savings
+        if "v" not in self.request.arguments:
+            self.add_header("Cache-Control", "no-cache")
+    
     def compute_etag(self):
         return None
     
     def validate_absolute_path(self, root, absolute_path):
         """Validate and return the absolute path.
         
         Requires tornado 3.1
         
         Adding to tornado's own handling, forbids the serving of hidden files.
         """
         abs_path = super(AuthenticatedFileHandler, self).validate_absolute_path(root, absolute_path)
         abs_root = os.path.abspath(root)
         if is_hidden(abs_path, abs_root):
             self.log.info("Refusing to serve hidden file, via 404 Error")
             raise web.HTTPError(404)
         return abs_path
 
 
 def json_errors(method):
     """Decorate methods with this to return GitHub style JSON errors.
     
     This should be used on any JSON API on any handler method that can raise HTTPErrors.
     
     This will grab the latest HTTPError exception using sys.exc_info
     and then:
     
     1. Set the HTTP status code based on the HTTPError
     2. Create and return a JSON body with a message field describing
        the error in a human readable form.
     """
     @functools.wraps(method)
     def wrapper(self, *args, **kwargs):
         try:
             result = method(self, *args, **kwargs)
         except web.HTTPError as e:
             status = e.status_code
             message = e.log_message
             self.log.warn(message)
             self.set_status(e.status_code)
             self.finish(json.dumps(dict(message=message)))
         except Exception:
             self.log.error("Unhandled error in API request", exc_info=True)
             status = 500
             message = "Unknown server error"
             t, value, tb = sys.exc_info()
             self.set_status(status)
             tb_text = ''.join(traceback.format_exception(t, value, tb))
             reply = dict(message=message, traceback=tb_text)
             self.finish(json.dumps(reply))
         else:
             return result
     return wrapper
 
 
 
 #-----------------------------------------------------------------------------
 # File handler
 #-----------------------------------------------------------------------------
 
 # to minimize subclass changes:
 HTTPError = web.HTTPError
 
 class FileFindHandler(web.StaticFileHandler):
     """subclass of StaticFileHandler for serving files from a search path"""
     
     # cache search results, don't search for files more than once
     _static_paths = {}
     
+    def set_headers(self):
+        super(FileFindHandler, self).set_headers()
+        # disable browser caching, rely in 304 replies for savings
+        if "v" not in self.request.arguments:
+            self.add_header("Cache-Control", "no-cache")
+    
     def initialize(self, path, default_filename=None):
         if isinstance(path, string_types):
             path = [path]
         
         self.root = tuple(
             os.path.abspath(os.path.expanduser(p)) + os.sep for p in path
         )
         self.default_filename = default_filename
     
     def compute_etag(self):
         return None
     
     @classmethod
     def get_absolute_path(cls, roots, path):
         """locate a file to serve on our static file search path"""
         with cls._lock:
             if path in cls._static_paths:
                 return cls._static_paths[path]
             try:
                 abspath = os.path.abspath(filefind(path, roots))
             except IOError:
                 # IOError means not found
                 return ''
             
             cls._static_paths[path] = abspath
             return abspath
     
     def validate_absolute_path(self, root, absolute_path):
         """check if the file should be served (raises 404, 403, etc.)"""
         if absolute_path == '':
             raise web.HTTPError(404)
         
         for root in self.root:
             if (absolute_path + os.sep).startswith(root):
                 break
         
         return super(FileFindHandler, self).validate_absolute_path(root, absolute_path)
 
 
 class ApiVersionHandler(IPythonHandler):
 
     @json_errors
     def get(self):
         # not authenticated, so give as few info as possible
         self.finish(json.dumps({"version":IPython.__version__}))
 
 
 class TrailingSlashHandler(web.RequestHandler):
     """Simple redirect handler that strips trailing slashes
     
     This should be the first, highest priority handler.
     """
     
     def get(self):
         self.redirect(self.request.uri.rstrip('/'))
     
     post = put = get
 
 
 class FilesRedirectHandler(IPythonHandler):
     """Handler for redirecting relative URLs to the /files/ handler"""
     def get(self, path=''):
         cm = self.contents_manager
         if cm.dir_exists(path):
             # it's a *directory*, redirect to /tree
             url = url_path_join(self.base_url, 'tree', path)
         else:
             orig_path = path
             # otherwise, redirect to /files
             parts = path.split('/')
 
             if not cm.file_exists(path=path) and 'files' in parts:
                 # redirect without files/ iff it would 404
                 # this preserves pre-2.0-style 'files/' links
                 self.log.warn("Deprecated files/ URL: %s", orig_path)
                 parts.remove('files')
                 path = '/'.join(parts)
 
             if not cm.file_exists(path=path):
                 raise web.HTTPError(404)
 
             url = url_path_join(self.base_url, 'files', path)
         url = url_escape(url)
         self.log.debug("Redirecting %s to %s", self.request.path, url)
         self.redirect(url)
 
 
 #-----------------------------------------------------------------------------
 # URL pattern fragments for re-use
 #-----------------------------------------------------------------------------
 
 # path matches any number of `/foo[/bar...]` or just `/` or ''
 path_regex = r"(?P<path>(?:(?:/[^/]+)+|/?))"
 notebook_path_regex = r"(?P<path>(?:/[^/]+)+\.ipynb)"
 
 #-----------------------------------------------------------------------------
 # URL to handler mappings
 #-----------------------------------------------------------------------------
 
 
 default_handlers = [
     (r".*/", TrailingSlashHandler),
     (r"api", ApiVersionHandler)
 ]