Adding JSON error handling and fixing location headers.

IPython/html/base/handlers.py

@@ -1,419 +1,457 b''
 """Base Tornado handlers for the notebook.
 
 Authors:
 
 * Brian Granger
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 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 datetime
 import email.utils
+import functools
 import hashlib
+import json
 import logging
 import mimetypes
 import os
 import stat
+import sys
 import threading
 
 from tornado import web
 from tornado import websocket
 
 try:
     from tornado.log import app_log
 except ImportError:
     app_log = logging.getLogger()
 
 from IPython.config import Application
 from IPython.external.decorator import decorator
 from IPython.utils.path import filefind
+from IPython.utils.jsonutil import date_default
 
 #-----------------------------------------------------------------------------
 # 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
 
 
 #-----------------------------------------------------------------------------
 # 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 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 = 'username-{host}'.format(
             host=self.request.host,
         ).replace(':', '-')
         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 use_less(self):
         """Use less instead of css in templates"""
         return self.settings.get('use_less', False)
     
     #---------------------------------------------------------------
     # URLs
     #---------------------------------------------------------------
     
     @property
     def ws_url(self):
         """websocket url matching the current request
 
         By default, this is just `''`, indicating that it should match
         the same host, protocol, port, etc.
         """
         return self.settings.get('websocket_url', '')
     
     @property
     def mathjax_url(self):
         return self.settings.get('mathjax_url', '')
     
     @property
     def base_project_url(self):
         return self.settings.get('base_project_url', '/')
     
     @property
     def base_kernel_url(self):
         return self.settings.get('base_kernel_url', '/')
     
     #---------------------------------------------------------------
     # Manager objects
     #---------------------------------------------------------------
     
     @property
     def kernel_manager(self):
         return self.settings['kernel_manager']
 
     @property
     def notebook_manager(self):
         return self.settings['notebook_manager']
     
     @property
     def cluster_manager(self):
         return self.settings['cluster_manager']
     
     @property
     def session_manager(self):
         return self.settings['session_manager']
     
     @property
     def project(self):
         return self.notebook_manager.notebook_dir
     
     #---------------------------------------------------------------
     # 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_project_url=self.base_project_url,
             base_kernel_url=self.base_kernel_url,
             logged_in=self.logged_in,
             login_available=self.login_available,
             use_less=self.use_less,
         )
 
+
 class AuthenticatedFileHandler(IPythonHandler, web.StaticFileHandler):
     """static files should only be accessible when logged in"""
 
     @web.authenticated
     def get(self, path):
         return web.StaticFileHandler.get(self, path)
 
 
+def json_errors(method):
+    """Decorate methods with this to return GitHub style JSON errors.
+    
+    This should be used 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:
+            t, value, tb = sys.exc_info()
+            if isinstance(value, web.HTTPError):
+                status = value.status_code
+                message = value.log_message
+            else:
+                status = 400
+                message = u"Unknown server error"
+            self.set_status(status)
+            reply = dict(message=message)
+            self.finish(json.dumps(reply, default=date_default))
+        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"""
     
     _static_paths = {}
     # _lock is needed for tornado < 2.2.0 compat
     _lock = threading.Lock()  # protects _static_hashes
     
     def initialize(self, path, default_filename=None):
         if isinstance(path, basestring):
             path = [path]
         self.roots = tuple(
             os.path.abspath(os.path.expanduser(p)) + os.path.sep for p in path
         )
         self.default_filename = default_filename
     
     @classmethod
     def locate_file(cls, path, roots):
         """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:
                 # empty string should always give exists=False
                 return ''
         
             # os.path.abspath strips a trailing /
             # it needs to be temporarily added back for requests to root/
             if not (abspath + os.path.sep).startswith(roots):
                 raise HTTPError(403, "%s is not in root static directory", path)
         
             cls._static_paths[path] = abspath
             return abspath
     
     def get(self, path, include_body=True):
         path = self.parse_url_path(path)
         
         # begin subclass override
         abspath = self.locate_file(path, self.roots)
         # end subclass override
         
         if os.path.isdir(abspath) and self.default_filename is not None:
             # need to look at the request.path here for when path is empty
             # but there is some prefix to the path that was already
             # trimmed by the routing
             if not self.request.path.endswith("/"):
                 self.redirect(self.request.path + "/")
                 return
             abspath = os.path.join(abspath, self.default_filename)
         if not os.path.exists(abspath):
             raise HTTPError(404)
         if not os.path.isfile(abspath):
             raise HTTPError(403, "%s is not a file", path)
 
         stat_result = os.stat(abspath)
         modified = datetime.datetime.utcfromtimestamp(stat_result[stat.ST_MTIME])
 
         self.set_header("Last-Modified", modified)
 
         mime_type, encoding = mimetypes.guess_type(abspath)
         if mime_type:
             self.set_header("Content-Type", mime_type)
 
         cache_time = self.get_cache_time(path, modified, mime_type)
 
         if cache_time > 0:
             self.set_header("Expires", datetime.datetime.utcnow() + \
                                        datetime.timedelta(seconds=cache_time))
             self.set_header("Cache-Control", "max-age=" + str(cache_time))
         else:
             self.set_header("Cache-Control", "public")
 
         self.set_extra_headers(path)
 
         # Check the If-Modified-Since, and don't send the result if the
         # content has not been modified
         ims_value = self.request.headers.get("If-Modified-Since")
         if ims_value is not None:
             date_tuple = email.utils.parsedate(ims_value)
             if_since = datetime.datetime(*date_tuple[:6])
             if if_since >= modified:
                 self.set_status(304)
                 return
 
         with open(abspath, "rb") as file:
             data = file.read()
             hasher = hashlib.sha1()
             hasher.update(data)
             self.set_header("Etag", '"%s"' % hasher.hexdigest())
             if include_body:
                 self.write(data)
             else:
                 assert self.request.method == "HEAD"
                 self.set_header("Content-Length", len(data))
 
     @classmethod
     def get_version(cls, settings, path):
         """Generate the version string to be used in static URLs.
 
         This method may be overridden in subclasses (but note that it
         is a class method rather than a static method).  The default
         implementation uses a hash of the file's contents.
 
         ``settings`` is the `Application.settings` dictionary and ``path``
         is the relative location of the requested asset on the filesystem.
         The returned value should be a string, or ``None`` if no version
         could be determined.
         """
         # begin subclass override:
         static_paths = settings['static_path']
         if isinstance(static_paths, basestring):
             static_paths = [static_paths]
         roots = tuple(
             os.path.abspath(os.path.expanduser(p)) + os.path.sep for p in static_paths
         )
 
         try:
             abs_path = filefind(path, roots)
         except IOError:
             app_log.error("Could not find static file %r", path)
             return None
         
         # end subclass override
         
         with cls._lock:
             hashes = cls._static_hashes
             if abs_path not in hashes:
                 try:
                     f = open(abs_path, "rb")
                     hashes[abs_path] = hashlib.md5(f.read()).hexdigest()
                     f.close()
                 except Exception:
                     app_log.error("Could not open static file %r", path)
                     hashes[abs_path] = None
             hsh = hashes.get(abs_path)
             if hsh:
                 return hsh[:5]
         return None
 
 
     def parse_url_path(self, url_path):
         """Converts a static URL path into a filesystem path.
 
         ``url_path`` is the path component of the URL with
         ``static_url_prefix`` removed.  The return value should be
         filesystem path relative to ``static_path``.
         """
         if os.path.sep != "/":
             url_path = url_path.replace("/", os.path.sep)
         return url_path
 
 #-----------------------------------------------------------------------------
 # URL to handler mappings
 #-----------------------------------------------------------------------------
 
 
 default_handlers = []