Source code for tornado.web

# Copyright 2009 Facebook
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

"""``tornado.web`` provides a simple web framework with asynchronous
features that allow it to scale to large numbers of open connections,
making it ideal for `long polling

Here is a simple "Hello, world" example app:

.. testcode::

    import asyncio
    import tornado

    class MainHandler(tornado.web.RequestHandler):
        def get(self):
            self.write("Hello, world")

    async def main():
        application = tornado.web.Application([
            (r"/", MainHandler),
        await asyncio.Event().wait()

    if __name__ == "__main__":

.. testoutput::

See the :doc:`guide` for additional information.

Thread-safety notes

In general, methods on `RequestHandler` and elsewhere in Tornado are
not thread-safe. In particular, methods such as
`~RequestHandler.write()`, `~RequestHandler.finish()`, and
`~RequestHandler.flush()` must only be called from the main thread. If
you use multiple threads it is important to use `.IOLoop.add_callback`
to transfer control back to the main thread before finishing the
request, or to limit your use of other threads to
`.IOLoop.run_in_executor` and ensure that your callbacks running in
the executor do not refer to Tornado objects.


import base64
import binascii
import datetime
import email.utils
import functools
import gzip
import hashlib
import hmac
import http.cookies
from inspect import isclass
from io import BytesIO
import mimetypes
import numbers
import os.path
import re
import socket
import sys
import threading
import time
import warnings
import tornado
import traceback
import types
import urllib.parse
from urllib.parse import urlencode

from tornado.concurrent import Future, future_set_result_unless_cancelled
from tornado import escape
from tornado import gen
from tornado.httpserver import HTTPServer
from tornado import httputil
from tornado import iostream
from tornado import locale
from tornado.log import access_log, app_log, gen_log
from tornado import template
from tornado.escape import utf8, _unicode
from tornado.routing import (
from tornado.util import ObjectDict, unicode_type, _websocket_mask

url = URLSpec

from typing import (
from types import TracebackType
import typing

if typing.TYPE_CHECKING:
    from typing import Set  # noqa: F401

# The following types are accepted by RequestHandler.set_header
# and related methods.
_HeaderTypes = Union[bytes, unicode_type, int, numbers.Integral, datetime.datetime]

_CookieSecretTypes = Union[str, bytes, Dict[int, str], Dict[int, bytes]]

"""The oldest signed value version supported by this version of Tornado.

Signed values older than this version cannot be decoded.

.. versionadded:: 3.2.1

"""The newest signed value version supported by this version of Tornado.

Signed values newer than this version cannot be decoded.

.. versionadded:: 3.2.1

"""The signed value version produced by `.RequestHandler.create_signed_value`.

May be overridden by passing a ``version`` keyword argument.

.. versionadded:: 3.2.1

"""The oldest signed value accepted by `.RequestHandler.get_signed_cookie`.

May be overridden by passing a ``min_version`` keyword argument.

.. versionadded:: 3.2.1

class _ArgDefaultMarker:

_ARG_DEFAULT = _ArgDefaultMarker()

[docs]class RequestHandler(object): """Base class for HTTP request handlers. Subclasses must define at least one of the methods defined in the "Entry points" section below. Applications should not construct `RequestHandler` objects directly and subclasses should not override ``__init__`` (override `~RequestHandler.initialize` instead). """ SUPPORTED_METHODS = ("GET", "HEAD", "POST", "DELETE", "PATCH", "PUT", "OPTIONS") _template_loaders = {} # type: Dict[str, template.BaseLoader] _template_loader_lock = threading.Lock() _remove_control_chars_regex = re.compile(r"[\x00-\x08\x0e-\x1f]") _stream_request_body = False # Will be set in _execute. _transforms = None # type: List[OutputTransform] path_args = None # type: List[str] path_kwargs = None # type: Dict[str, str] def __init__( self, application: "Application", request: httputil.HTTPServerRequest, **kwargs: Any, ) -> None: super().__init__() self.application = application self.request = request self._headers_written = False self._finished = False self._auto_finish = True self._prepared_future = None self.ui = ObjectDict( (n, self._ui_method(m)) for n, m in application.ui_methods.items() ) # UIModules are available as both `modules` and `_tt_modules` in the # template namespace. Historically only `modules` was available # but could be clobbered by user additions to the namespace. # The template {% module %} directive looks in `_tt_modules` to avoid # possible conflicts. self.ui["_tt_modules"] = _UIModuleNamespace(self, application.ui_modules) self.ui["modules"] = self.ui["_tt_modules"] self.clear() assert self.request.connection is not None # TODO: need to add set_close_callback to HTTPConnection interface self.request.connection.set_close_callback( # type: ignore self.on_connection_close ) self.initialize(**kwargs) # type: ignore def _initialize(self) -> None: pass initialize = _initialize # type: Callable[..., None] """Hook for subclass initialization. Called for each request. A dictionary passed as the third argument of a ``URLSpec`` will be supplied as keyword arguments to ``initialize()``. Example:: class ProfileHandler(RequestHandler): def initialize(self, database): self.database = database def get(self, username): ... app = Application([ (r'/user/(.*)', ProfileHandler, dict(database=database)), ]) """ @property def settings(self) -> Dict[str, Any]: """An alias for `self.application.settings <Application.settings>`.""" return self.application.settings def _unimplemented_method(self, *args: str, **kwargs: str) -> None: raise HTTPError(405) head = _unimplemented_method # type: Callable[..., Optional[Awaitable[None]]] get = _unimplemented_method # type: Callable[..., Optional[Awaitable[None]]] post = _unimplemented_method # type: Callable[..., Optional[Awaitable[None]]] delete = _unimplemented_method # type: Callable[..., Optional[Awaitable[None]]] patch = _unimplemented_method # type: Callable[..., Optional[Awaitable[None]]] put = _unimplemented_method # type: Callable[..., Optional[Awaitable[None]]] options = _unimplemented_method # type: Callable[..., Optional[Awaitable[None]]]
[docs] def prepare(self) -> Optional[Awaitable[None]]: """Called at the beginning of a request before `get`/`post`/etc. Override this method to perform common initialization regardless of the request method. Asynchronous support: Use ``async def`` or decorate this method with `.gen.coroutine` to make it asynchronous. If this method returns an ``Awaitable`` execution will not proceed until the ``Awaitable`` is done. .. versionadded:: 3.1 Asynchronous support. """ pass
[docs] def on_finish(self) -> None: """Called after the end of a request. Override this method to perform cleanup, logging, etc. This method is a counterpart to `prepare`. ``on_finish`` may not produce any output, as it is called after the response has been sent to the client. """ pass
[docs] def on_connection_close(self) -> None: """Called in async handlers if the client closed the connection. Override this to clean up resources associated with long-lived connections. Note that this method is called only if the connection was closed during asynchronous processing; if you need to do cleanup after every request override `on_finish` instead. Proxies may keep a connection open for a time (perhaps indefinitely) after the client has gone away, so this method may not be called promptly after the end user closes their connection. """ if _has_stream_request_body(self.__class__): if not self.request._body_future.done(): self.request._body_future.set_exception(iostream.StreamClosedError()) self.request._body_future.exception()
[docs] def clear(self) -> None: """Resets all headers and content for this response.""" self._headers = httputil.HTTPHeaders( { "Server": "TornadoServer/%s" % tornado.version, "Content-Type": "text/html; charset=UTF-8", "Date": httputil.format_timestamp(time.time()), } ) self.set_default_headers() self._write_buffer = [] # type: List[bytes] self._status_code = 200 self._reason = httputil.responses[200]
[docs] def set_default_headers(self) -> None: """Override this to set HTTP headers at the beginning of the request. For example, this is the place to set a custom ``Server`` header. Note that setting such headers in the normal flow of request processing may not do what you want, since headers may be reset during error handling. """ pass
[docs] def set_status(self, status_code: int, reason: Optional[str] = None) -> None: """Sets the status code for our response. :arg int status_code: Response status code. :arg str reason: Human-readable reason phrase describing the status code. If ``None``, it will be filled in from `http.client.responses` or "Unknown". .. versionchanged:: 5.0 No longer validates that the response code is in `http.client.responses`. """ self._status_code = status_code if reason is not None: self._reason = escape.native_str(reason) else: self._reason = httputil.responses.get(status_code, "Unknown")
[docs] def get_status(self) -> int: """Returns the status code for our response.""" return self._status_code
[docs] def set_header(self, name: str, value: _HeaderTypes) -> None: """Sets the given response header name and value. All header values are converted to strings (`datetime` objects are formatted according to the HTTP specification for the ``Date`` header). """ self._headers[name] = self._convert_header_value(value)
[docs] def add_header(self, name: str, value: _HeaderTypes) -> None: """Adds the given response header and value. Unlike `set_header`, `add_header` may be called multiple times to return multiple values for the same header. """ self._headers.add(name, self._convert_header_value(value))
[docs] def clear_header(self, name: str) -> None: """Clears an outgoing header, undoing a previous `set_header` call. Note that this method does not apply to multi-valued headers set by `add_header`. """ if name in self._headers: del self._headers[name]
_INVALID_HEADER_CHAR_RE = re.compile(r"[\x00-\x1f]") def _convert_header_value(self, value: _HeaderTypes) -> str: # Convert the input value to a str. This type check is a bit # subtle: The bytes case only executes on python 3, and the # unicode case only executes on python 2, because the other # cases are covered by the first match for str. if isinstance(value, str): retval = value elif isinstance(value, bytes): # Non-ascii characters in headers are not well supported, # but if you pass bytes, use latin1 so they pass through as-is. retval = value.decode("latin1") elif isinstance(value, numbers.Integral): # return immediately since we know the converted value will be safe return str(value) elif isinstance(value, datetime.datetime): return httputil.format_timestamp(value) else: raise TypeError("Unsupported header value %r" % value) # If \n is allowed into the header, it is possible to inject # additional headers or split the request. if raise ValueError("Unsafe header value %r", retval) return retval @overload def get_argument(self, name: str, default: str, strip: bool = True) -> str: pass @overload def get_argument( # noqa: F811 self, name: str, default: _ArgDefaultMarker = _ARG_DEFAULT, strip: bool = True ) -> str: pass @overload def get_argument( # noqa: F811 self, name: str, default: None, strip: bool = True ) -> Optional[str]: pass
[docs] def get_argument( # noqa: F811 self, name: str, default: Union[None, str, _ArgDefaultMarker] = _ARG_DEFAULT, strip: bool = True, ) -> Optional[str]: """Returns the value of the argument with the given name. If default is not provided, the argument is considered to be required, and we raise a `MissingArgumentError` if it is missing. If the argument appears in the request more than once, we return the last value. This method searches both the query and body arguments. """ return self._get_argument(name, default, self.request.arguments, strip)
[docs] def get_arguments(self, name: str, strip: bool = True) -> List[str]: """Returns a list of the arguments with the given name. If the argument is not present, returns an empty list. This method searches both the query and body arguments. """ # Make sure `get_arguments` isn't accidentally being called with a # positional argument that's assumed to be a default (like in # `get_argument`.) assert isinstance(strip, bool) return self._get_arguments(name, self.request.arguments, strip)
[docs] def get_body_argument( self, name: str, default: Union[None, str, _ArgDefaultMarker] = _ARG_DEFAULT, strip: bool = True, ) -> Optional[str]: """Returns the value of the argument with the given name from the request body. If default is not provided, the argument is considered to be required, and we raise a `MissingArgumentError` if it is missing. If the argument appears in the url more than once, we return the last value. .. versionadded:: 3.2 """ return self._get_argument(name, default, self.request.body_arguments, strip)
[docs] def get_body_arguments(self, name: str, strip: bool = True) -> List[str]: """Returns a list of the body arguments with the given name. If the argument is not present, returns an empty list. .. versionadded:: 3.2 """ return self._get_arguments(name, self.request.body_arguments, strip)
[docs] def get_query_argument( self, name: str, default: Union[None, str, _ArgDefaultMarker] = _ARG_DEFAULT, strip: bool = True, ) -> Optional[str]: """Returns the value of the argument with the given name from the request query string. If default is not provided, the argument is considered to be required, and we raise a `MissingArgumentError` if it is missing. If the argument appears in the url more than once, we return the last value. .. versionadded:: 3.2 """ return self._get_argument(name, default, self.request.query_arguments, strip)
[docs] def get_query_arguments(self, name: str, strip: bool = True) -> List[str]: """Returns a list of the query arguments with the given name. If the argument is not present, returns an empty list. .. versionadded:: 3.2 """ return self._get_arguments(name, self.request.query_arguments, strip)
def _get_argument( self, name: str, default: Union[None, str, _ArgDefaultMarker], source: Dict[str, List[bytes]], strip: bool = True, ) -> Optional[str]: args = self._get_arguments(name, source, strip=strip) if not args: if isinstance(default, _ArgDefaultMarker): raise MissingArgumentError(name) return default return args[-1] def _get_arguments( self, name: str, source: Dict[str, List[bytes]], strip: bool = True ) -> List[str]: values = [] for v in source.get(name, []): s = self.decode_argument(v, name=name) if isinstance(s, unicode_type): # Get rid of any weird control chars (unless decoding gave # us bytes, in which case leave it alone) s = RequestHandler._remove_control_chars_regex.sub(" ", s) if strip: s = s.strip() values.append(s) return values
[docs] def decode_argument(self, value: bytes, name: Optional[str] = None) -> str: """Decodes an argument from the request. The argument has been percent-decoded and is now a byte string. By default, this method decodes the argument as utf-8 and returns a unicode string, but this may be overridden in subclasses. This method is used as a filter for both `get_argument()` and for values extracted from the url and passed to `get()`/`post()`/etc. The name of the argument is provided if known, but may be None (e.g. for unnamed groups in the url regex). """ try: return _unicode(value) except UnicodeDecodeError: raise HTTPError( 400, "Invalid unicode in %s: %r" % (name or "url", value[:40]) )
@property def cookies(self) -> Dict[str, http.cookies.Morsel]: """An alias for `self.request.cookies <.httputil.HTTPServerRequest.cookies>`.""" return self.request.cookies
[docs] def clear_all_cookies(self, **kwargs: Any) -> None: """Attempt to delete all the cookies the user sent with this request. See `clear_cookie` for more information on keyword arguments. Due to limitations of the cookie protocol, it is impossible to determine on the server side which values are necessary for the ``domain``, ``path``, ``samesite``, or ``secure`` arguments, this method can only be successful if you consistently use the same values for these arguments when setting cookies. Similar to `set_cookie`, the effect of this method will not be seen until the following request. .. versionchanged:: 3.2 Added the ``path`` and ``domain`` parameters. .. versionchanged:: 6.3 Now accepts all keyword arguments that ``set_cookie`` does. .. deprecated:: 6.3 The increasingly complex rules governing cookies have made it impossible for a ``clear_all_cookies`` method to work reliably since all we know about cookies are their names. Applications should generally use ``clear_cookie`` one at a time instead. """ for name in self.request.cookies: self.clear_cookie(name, **kwargs)
set_secure_cookie = set_signed_cookie
[docs] def create_signed_value( self, name: str, value: Union[str, bytes], version: Optional[int] = None ) -> bytes: """Signs and timestamps a string so it cannot be forged. Normally used via set_signed_cookie, but provided as a separate method for non-cookie uses. To decode a value not stored as a cookie use the optional value argument to get_signed_cookie. .. versionchanged:: 3.2.1 Added the ``version`` argument. Introduced cookie version 2 and made it the default. """ self.require_setting("cookie_secret", "secure cookies") secret = self.application.settings["cookie_secret"] key_version = None if isinstance(secret, dict): if self.application.settings.get("key_version") is None: raise Exception("key_version setting must be used for secret_key dicts") key_version = self.application.settings["key_version"] return create_signed_value( secret, name, value, version=version, key_version=key_version )
get_secure_cookie = get_signed_cookie get_secure_cookie_key_version = get_signed_cookie_key_version
[docs] def redirect( self, url: str, permanent: bool = False, status: Optional[int] = None ) -> None: """Sends a redirect to the given (optionally relative) URL. If the ``status`` argument is specified, that value is used as the HTTP status code; otherwise either 301 (permanent) or 302 (temporary) is chosen based on the ``permanent`` argument. The default is 302 (temporary). """ if self._headers_written: raise Exception("Cannot redirect after headers have been written") if status is None: status = 301 if permanent else 302 else: assert isinstance(status, int) and 300 <= status <= 399 self.set_status(status) self.set_header("Location", utf8(url)) self.finish()
[docs] def write(self, chunk: Union[str, bytes, dict]) -> None: """Writes the given chunk to the output buffer. To write the output to the network, use the `flush()` method below. If the given chunk is a dictionary, we write it as JSON and set the Content-Type of the response to be ``application/json``. (if you want to send JSON as a different ``Content-Type``, call ``set_header`` *after* calling ``write()``). Note that lists are not converted to JSON because of a potential cross-site security vulnerability. All JSON output should be wrapped in a dictionary. More details at and """ if self._finished: raise RuntimeError("Cannot write() after finish()") if not isinstance(chunk, (bytes, unicode_type, dict)): message = "write() only accepts bytes, unicode, and dict objects" if isinstance(chunk, list): message += ( ". Lists not accepted for security reasons; see " + "" # noqa: E501 ) raise TypeError(message) if isinstance(chunk, dict): chunk = escape.json_encode(chunk) self.set_header("Content-Type", "application/json; charset=UTF-8") chunk = utf8(chunk) self._write_buffer.append(chunk)
[docs] def render(self, template_name: str, **kwargs: Any) -> "Future[None]": """Renders the template with the given arguments as the response. ``render()`` calls ``finish()``, so no other output methods can be called after it. Returns a `.Future` with the same semantics as the one returned by `finish`. Awaiting this `.Future` is optional. .. versionchanged:: 5.1 Now returns a `.Future` instead of ``None``. """ if self._finished: raise RuntimeError("Cannot render() after finish()") html = self.render_string(template_name, **kwargs) # Insert the additional JS and CSS added by the modules on the page js_embed = [] js_files = [] css_embed = [] css_files = [] html_heads = [] html_bodies = [] for module in getattr(self, "_active_modules", {}).values(): embed_part = module.embedded_javascript() if embed_part: js_embed.append(utf8(embed_part)) file_part = module.javascript_files() if file_part: if isinstance(file_part, (unicode_type, bytes)): js_files.append(_unicode(file_part)) else: js_files.extend(file_part) embed_part = module.embedded_css() if embed_part: css_embed.append(utf8(embed_part)) file_part = module.css_files() if file_part: if isinstance(file_part, (unicode_type, bytes)): css_files.append(_unicode(file_part)) else: css_files.extend(file_part) head_part = module.html_head() if head_part: html_heads.append(utf8(head_part)) body_part = module.html_body() if body_part: html_bodies.append(utf8(body_part)) if js_files: # Maintain order of JavaScript files given by modules js = self.render_linked_js(js_files) sloc = html.rindex(b"</body>") html = html[:sloc] + utf8(js) + b"\n" + html[sloc:] if js_embed: js_bytes = self.render_embed_js(js_embed) sloc = html.rindex(b"</body>") html = html[:sloc] + js_bytes + b"\n" + html[sloc:] if css_files: css = self.render_linked_css(css_files) hloc = html.index(b"</head>") html = html[:hloc] + utf8(css) + b"\n" + html[hloc:] if css_embed: css_bytes = self.render_embed_css(css_embed) hloc = html.index(b"</head>") html = html[:hloc] + css_bytes + b"\n" + html[hloc:] if html_heads: hloc = html.index(b"</head>") html = html[:hloc] + b"".join(html_heads) + b"\n" + html[hloc:] if html_bodies: hloc = html.index(b"</body>") html = html[:hloc] + b"".join(html_bodies) + b"\n" + html[hloc:] return self.finish(html)
[docs] def render_linked_js(self, js_files: Iterable[str]) -> str: """Default method used to render the final js links for the rendered webpage. Override this method in a sub-classed controller to change the output. """ paths = [] unique_paths = set() # type: Set[str] for path in js_files: if not is_absolute(path): path = self.static_url(path) if path not in unique_paths: paths.append(path) unique_paths.add(path) return "".join( '<script src="' + escape.xhtml_escape(p) + '" type="text/javascript"></script>' for p in paths )
[docs] def render_embed_js(self, js_embed: Iterable[bytes]) -> bytes: """Default method used to render the final embedded js for the rendered webpage. Override this method in a sub-classed controller to change the output. """ return ( b'<script type="text/javascript">\n//<![CDATA[\n' + b"\n".join(js_embed) + b"\n//]]>\n</script>" )
[docs] def render_linked_css(self, css_files: Iterable[str]) -> str: """Default method used to render the final css links for the rendered webpage. Override this method in a sub-classed controller to change the output. """ paths = [] unique_paths = set() # type: Set[str] for path in css_files: if not is_absolute(path): path = self.static_url(path) if path not in unique_paths: paths.append(path) unique_paths.add(path) return "".join( '<link href="' + escape.xhtml_escape(p) + '" ' 'type="text/css" rel="stylesheet"/>' for p in paths )
[docs] def render_embed_css(self, css_embed: Iterable[bytes]) -> bytes: """Default method used to render the final embedded css for the rendered webpage. Override this method in a sub-classed controller to change the output. """ return b'<style type="text/css">\n' + b"\n".join(css_embed) + b"\n</style>"
[docs] def render_string(self, template_name: str, **kwargs: Any) -> bytes: """Generate the given template with the given arguments. We return the generated byte string (in utf8). To generate and write a template as a response, use render() above. """ # If no template_path is specified, use the path of the calling file template_path = self.get_template_path() if not template_path: frame = sys._getframe(0) web_file = frame.f_code.co_filename while frame.f_code.co_filename == web_file and frame.f_back is not None: frame = frame.f_back assert frame.f_code.co_filename is not None template_path = os.path.dirname(frame.f_code.co_filename) with RequestHandler._template_loader_lock: if template_path not in RequestHandler._template_loaders: loader = self.create_template_loader(template_path) RequestHandler._template_loaders[template_path] = loader else: loader = RequestHandler._template_loaders[template_path] t = loader.load(template_name) namespace = self.get_template_namespace() namespace.update(kwargs) return t.generate(**namespace)
[docs] def get_template_namespace(self) -> Dict[str, Any]: """Returns a dictionary to be used as the default template namespace. May be overridden by subclasses to add or modify values. The results of this method will be combined with additional defaults in the `tornado.template` module and keyword arguments to `render` or `render_string`. """ namespace = dict( handler=self, request=self.request, current_user=self.current_user, locale=self.locale, _=self.locale.translate, pgettext=self.locale.pgettext, static_url=self.static_url, xsrf_form_html=self.xsrf_form_html, reverse_url=self.reverse_url, ) namespace.update(self.ui) return namespace
[docs] def create_template_loader(self, template_path: str) -> template.BaseLoader: """Returns a new template loader for the given path. May be overridden by subclasses. By default returns a directory-based loader on the given path, using the ``autoescape`` and ``template_whitespace`` application settings. If a ``template_loader`` application setting is supplied, uses that instead. """ settings = self.application.settings if "template_loader" in settings: return settings["template_loader"] kwargs = {} if "autoescape" in settings: # autoescape=None means "no escaping", so we have to be sure # to only pass this kwarg if the user asked for it. kwargs["autoescape"] = settings["autoescape"] if "template_whitespace" in settings: kwargs["whitespace"] = settings["template_whitespace"] return template.Loader(template_path, **kwargs)
[docs] def flush(self, include_footers: bool = False) -> "Future[None]": """Flushes the current output buffer to the network. .. versionchanged:: 4.0 Now returns a `.Future` if no callback is given. .. versionchanged:: 6.0 The ``callback`` argument was removed. """ assert self.request.connection is not None chunk = b"".join(self._write_buffer) self._write_buffer = [] if not self._headers_written: self._headers_written = True for transform in self._transforms: assert chunk is not None ( self._status_code, self._headers, chunk, ) = transform.transform_first_chunk( self._status_code, self._headers, chunk, include_footers ) # Ignore the chunk and only write the headers for HEAD requests if self.request.method == "HEAD": chunk = b"" # Finalize the cookie headers (which have been stored in a side # object so an outgoing cookie could be overwritten before it # is sent). if hasattr(self, "_new_cookie"): for cookie in self._new_cookie.values(): self.add_header("Set-Cookie", cookie.OutputString(None)) start_line = httputil.ResponseStartLine("", self._status_code, self._reason) return self.request.connection.write_headers( start_line, self._headers, chunk ) else: for transform in self._transforms: chunk = transform.transform_chunk(chunk, include_footers) # Ignore the chunk and only write the headers for HEAD requests if self.request.method != "HEAD": return self.request.connection.write(chunk) else: future = Future() # type: Future[None] future.set_result(None) return future
[docs] def finish(self, chunk: Optional[Union[str, bytes, dict]] = None) -> "Future[None]": """Finishes this response, ending the HTTP request. Passing a ``chunk`` to ``finish()`` is equivalent to passing that chunk to ``write()`` and then calling ``finish()`` with no arguments. Returns a `.Future` which may optionally be awaited to track the sending of the response to the client. This `.Future` resolves when all the response data has been sent, and raises an error if the connection is closed before all data can be sent. .. versionchanged:: 5.1 Now returns a `.Future` instead of ``None``. """ if self._finished: raise RuntimeError("finish() called twice") if chunk is not None: self.write(chunk) # Automatically support ETags and add the Content-Length header if # we have not flushed any content yet. if not self._headers_written: if ( self._status_code == 200 and self.request.method in ("GET", "HEAD") and "Etag" not in self._headers ): self.set_etag_header() if self.check_etag_header(): self._write_buffer = [] self.set_status(304) if self._status_code in (204, 304) or (100 <= self._status_code < 200): assert not self._write_buffer, ( "Cannot send body with %s" % self._status_code ) self._clear_representation_headers() elif "Content-Length" not in self._headers: content_length = sum(len(part) for part in self._write_buffer) self.set_header("Content-Length", content_length) assert self.request.connection is not None # Now that the request is finished, clear the callback we # set on the HTTPConnection (which would otherwise prevent the # garbage collection of the RequestHandler when there # are keepalive connections) self.request.connection.set_close_callback(None) # type: ignore future = self.flush(include_footers=True) self.request.connection.finish() self._log() self._finished = True self.on_finish() self._break_cycles() return future
[docs] def detach(self) -> iostream.IOStream: """Take control of the underlying stream. Returns the underlying `.IOStream` object and stops all further HTTP processing. Intended for implementing protocols like websockets that tunnel over an HTTP handshake. This method is only supported when HTTP/1.1 is used. .. versionadded:: 5.1 """ self._finished = True # TODO: add detach to HTTPConnection? return self.request.connection.detach() # type: ignore
def _break_cycles(self) -> None: # Break up a reference cycle between this handler and the # _ui_module closures to allow for faster GC on CPython. self.ui = None # type: ignore
[docs] def send_error(self, status_code: int = 500, **kwargs: Any) -> None: """Sends the given HTTP error code to the browser. If `flush()` has already been called, it is not possible to send an error, so this method will simply terminate the response. If output has been written but not yet flushed, it will be discarded and replaced with the error page. Override `write_error()` to customize the error page that is returned. Additional keyword arguments are passed through to `write_error`. """ if self._headers_written: gen_log.error("Cannot send error response after headers written") if not self._finished: # If we get an error between writing headers and finishing, # we are unlikely to be able to finish due to a # Content-Length mismatch. Try anyway to release the # socket. try: self.finish() except Exception: gen_log.error("Failed to flush partial response", exc_info=True) return self.clear() reason = kwargs.get("reason") if "exc_info" in kwargs: exception = kwargs["exc_info"][1] if isinstance(exception, HTTPError) and exception.reason: reason = exception.reason self.set_status(status_code, reason=reason) try: self.write_error(status_code, **kwargs) except Exception: app_log.error("Uncaught exception in write_error", exc_info=True) if not self._finished: self.finish()
[docs] def write_error(self, status_code: int, **kwargs: Any) -> None: """Override to implement custom error pages. ``write_error`` may call `write`, `render`, `set_header`, etc to produce output as usual. If this error was caused by an uncaught exception (including HTTPError), an ``exc_info`` triple will be available as ``kwargs["exc_info"]``. Note that this exception may not be the "current" exception for purposes of methods like ``sys.exc_info()`` or ``traceback.format_exc``. """ if self.settings.get("serve_traceback") and "exc_info" in kwargs: # in debug mode, try to send a traceback self.set_header("Content-Type", "text/plain") for line in traceback.format_exception(*kwargs["exc_info"]): self.write(line) self.finish() else: self.finish( "<html><title>%(code)d: %(message)s</title>" "<body>%(code)d: %(message)s</body></html>" % {"code": status_code, "message": self._reason} )
@property def locale(self) -> tornado.locale.Locale: """The locale for the current session. Determined by either `get_user_locale`, which you can override to set the locale based on, e.g., a user preference stored in a database, or `get_browser_locale`, which uses the ``Accept-Language`` header. .. versionchanged: 4.1 Added a property setter. """ if not hasattr(self, "_locale"): loc = self.get_user_locale() if loc is not None: self._locale = loc else: self._locale = self.get_browser_locale() assert self._locale return self._locale @locale.setter def locale(self, value: tornado.locale.Locale) -> None: self._locale = value
[docs] def get_user_locale(self) -> Optional[tornado.locale.Locale]: """Override to determine the locale from the authenticated user. If None is returned, we fall back to `get_browser_locale()`. This method should return a `tornado.locale.Locale` object, most likely obtained via a call like ``tornado.locale.get("en")`` """ return None
[docs] def get_browser_locale(self, default: str = "en_US") -> tornado.locale.Locale: """Determines the user's locale from ``Accept-Language`` header. See """ if "Accept-Language" in self.request.headers: languages = self.request.headers["Accept-Language"].split(",") locales = [] for language in languages: parts = language.strip().split(";") if len(parts) > 1 and parts[1].strip().startswith("q="): try: score = float(parts[1].strip()[2:]) if score < 0: raise ValueError() except (ValueError, TypeError): score = 0.0 else: score = 1.0 if score > 0: locales.append((parts[0], score)) if locales: locales.sort(key=lambda pair: pair[1], reverse=True) codes = [loc[0] for loc in locales] return locale.get(*codes) return locale.get(default)
@property def current_user(self) -> Any: """The authenticated user for this request. This is set in one of two ways: * A subclass may override `get_current_user()`, which will be called automatically the first time ``self.current_user`` is accessed. `get_current_user()` will only be called once per request, and is cached for future access:: def get_current_user(self): user_cookie = self.get_signed_cookie("user") if user_cookie: return json.loads(user_cookie) return None * It may be set as a normal variable, typically from an overridden `prepare()`:: @gen.coroutine def prepare(self): user_id_cookie = self.get_signed_cookie("user_id") if user_id_cookie: self.current_user = yield load_user(user_id_cookie) Note that `prepare()` may be a coroutine while `get_current_user()` may not, so the latter form is necessary if loading the user requires asynchronous operations. The user object may be any type of the application's choosing. """ if not hasattr(self, "_current_user"): self._current_user = self.get_current_user() return self._current_user @current_user.setter def current_user(self, value: Any) -> None: self._current_user = value
[docs] def get_current_user(self) -> Any: """Override to determine the current user from, e.g., a cookie. This method may not be a coroutine. """ return None
[docs] def get_login_url(self) -> str: """Override to customize the login URL based on the request. By default, we use the ``login_url`` application setting. """ self.require_setting("login_url", "@tornado.web.authenticated") return self.application.settings["login_url"]
[docs] def get_template_path(self) -> Optional[str]: """Override to customize template path for each handler. By default, we use the ``template_path`` application setting. Return None to load templates relative to the calling file. """ return self.application.settings.get("template_path")
@property def xsrf_token(self) -> bytes: """The XSRF-prevention token for the current user/session. To prevent cross-site request forgery, we set an '_xsrf' cookie and include the same '_xsrf' value as an argument with all POST requests. If the two do not match, we reject the form submission as a potential forgery. See This property is of type `bytes`, but it contains only ASCII characters. If a character string is required, there is no need to base64-encode it; just decode the byte string as UTF-8. .. versionchanged:: 3.2.2 The xsrf token will now be have a random mask applied in every request, which makes it safe to include the token in pages that are compressed. See for more information on the issue fixed by this change. Old (version 1) cookies will be converted to version 2 when this method is called unless the ``xsrf_cookie_version`` `Application` setting is set to 1. .. versionchanged:: 4.3 The ``xsrf_cookie_kwargs`` `Application` setting may be used to supply additional cookie options (which will be passed directly to `set_cookie`). For example, ``xsrf_cookie_kwargs=dict(httponly=True, secure=True)`` will set the ``secure`` and ``httponly`` flags on the ``_xsrf`` cookie. """ if not hasattr(self, "_xsrf_token"): version, token, timestamp = self._get_raw_xsrf_token() output_version = self.settings.get("xsrf_cookie_version", 2) cookie_kwargs = self.settings.get("xsrf_cookie_kwargs", {}) if output_version == 1: self._xsrf_token = binascii.b2a_hex(token) elif output_version == 2: mask = os.urandom(4) self._xsrf_token = b"|".join( [ b"2", binascii.b2a_hex(mask), binascii.b2a_hex(_websocket_mask(mask, token)), utf8(str(int(timestamp))), ] ) else: raise ValueError("unknown xsrf cookie version %d", output_version) if version is None: if self.current_user and "expires_days" not in cookie_kwargs: cookie_kwargs["expires_days"] = 30 cookie_name = self.settings.get("xsrf_cookie_name", "_xsrf") self.set_cookie(cookie_name, self._xsrf_token, **cookie_kwargs) return self._xsrf_token def _get_raw_xsrf_token(self) -> Tuple[Optional[int], bytes, float]: """Read or generate the xsrf token in its raw form. The raw_xsrf_token is a tuple containing: * version: the version of the cookie from which this token was read, or None if we generated a new token in this request. * token: the raw token data; random (non-ascii) bytes. * timestamp: the time this token was generated (will not be accurate for version 1 cookies) """ if not hasattr(self, "_raw_xsrf_token"): cookie_name = self.settings.get("xsrf_cookie_name", "_xsrf") cookie = self.get_cookie(cookie_name) if cookie: version, token, timestamp = self._decode_xsrf_token(cookie) else: version, token, timestamp = None, None, None if token is None: version = None token = os.urandom(16) timestamp = time.time() assert token is not None assert timestamp is not None self._raw_xsrf_token = (version, token, timestamp) return self._raw_xsrf_token def _decode_xsrf_token( self, cookie: str ) -> Tuple[Optional[int], Optional[bytes], Optional[float]]: """Convert a cookie string into a the tuple form returned by _get_raw_xsrf_token. """ try: m = _signed_value_version_re.match(utf8(cookie)) if m: version = int( if version == 2: _, mask_str, masked_token, timestamp_str = cookie.split("|") mask = binascii.a2b_hex(utf8(mask_str)) token = _websocket_mask(mask, binascii.a2b_hex(utf8(masked_token))) timestamp = int(timestamp_str) return version, token, timestamp else: # Treat unknown versions as not present instead of failing. raise Exception("Unknown xsrf cookie version") else: version = 1 try: token = binascii.a2b_hex(utf8(cookie)) except (binascii.Error, TypeError): token = utf8(cookie) # We don't have a usable timestamp in older versions. timestamp = int(time.time()) return (version, token, timestamp) except Exception: # Catch exceptions and return nothing instead of failing. gen_log.debug("Uncaught exception in _decode_xsrf_token", exc_info=True) return None, None, None
[docs] def xsrf_form_html(self) -> str: """An HTML ``<input/>`` element to be included with all POST forms. It defines the ``_xsrf`` input value, which we check on all POST requests to prevent cross-site request forgery. If you have set the ``xsrf_cookies`` application setting, you must include this HTML within all of your HTML forms. In a template, this method should be called with ``{% module xsrf_form_html() %}`` See `check_xsrf_cookie()` above for more information. """ return ( '<input type="hidden" name="_xsrf" value="' + escape.xhtml_escape(self.xsrf_token) + '"/>' )
[docs] def static_url( self, path: str, include_host: Optional[bool] = None, **kwargs: Any ) -> str: """Returns a static URL for the given relative static file path. This method requires you set the ``static_path`` setting in your application (which specifies the root directory of your static files). This method returns a versioned url (by default appending ``?v=<signature>``), which allows the static files to be cached indefinitely. This can be disabled by passing ``include_version=False`` (in the default implementation; other static file implementations are not required to support this, but they may support other options). By default this method returns URLs relative to the current host, but if ``include_host`` is true the URL returned will be absolute. If this handler has an ``include_host`` attribute, that value will be used as the default for all `static_url` calls that do not pass ``include_host`` as a keyword argument. """ self.require_setting("static_path", "static_url") get_url = self.settings.get( "static_handler_class", StaticFileHandler ).make_static_url if include_host is None: include_host = getattr(self, "include_host", False) if include_host: base = self.request.protocol + "://" + else: base = "" return base + get_url(self.settings, path, **kwargs)
[docs] def require_setting(self, name: str, feature: str = "this feature") -> None: """Raises an exception if the given app setting is not defined.""" if not self.application.settings.get(name): raise Exception( "You must define the '%s' setting in your " "application to use %s" % (name, feature) )
[docs] def reverse_url(self, name: str, *args: Any) -> str: """Alias for `Application.reverse_url`.""" return self.application.reverse_url(name, *args)
[docs] def compute_etag(self) -> Optional[str]: """Computes the etag header to be used for this request. By default uses a hash of the content written so far. May be overridden to provide custom etag implementations, or may return None to disable tornado's default etag support. """ hasher = hashlib.sha1() for part in self._write_buffer: hasher.update(part) return '"%s"' % hasher.hexdigest()
[docs] def set_etag_header(self) -> None: """Sets the response's Etag header using ``self.compute_etag()``. Note: no header will be set if ``compute_etag()`` returns ``None``. This method is called automatically when the request is finished. """ etag = self.compute_etag() if etag is not None: self.set_header("Etag", etag)
[docs] def check_etag_header(self) -> bool: """Checks the ``Etag`` header against requests's ``If-None-Match``. Returns ``True`` if the request's Etag matches and a 304 should be returned. For example:: self.set_etag_header() if self.check_etag_header(): self.set_status(304) return This method is called automatically when the request is finished, but may be called earlier for applications that override `compute_etag` and want to do an early check for ``If-None-Match`` before completing the request. The ``Etag`` header should be set (perhaps with `set_etag_header`) before calling this method. """ computed_etag = utf8(self._headers.get("Etag", "")) # Find all weak and strong etag values from If-None-Match header # because RFC 7232 allows multiple etag values in a single header. etags = re.findall( rb'\*|(?:W/)?"[^"]*"', utf8(self.request.headers.get("If-None-Match", "")) ) if not computed_etag or not etags: return False match = False if etags[0] == b"*": match = True else: # Use a weak comparison when comparing entity-tags. def val(x: bytes) -> bytes: return x[2:] if x.startswith(b"W/") else x for etag in etags: if val(etag) == val(computed_etag): match = True break return match
async def _execute( self, transforms: List["OutputTransform"], *args: bytes, **kwargs: bytes ) -> None: """Executes this request with the given output transforms.""" self._transforms = transforms try: if self.request.method not in self.SUPPORTED_METHODS: raise HTTPError(405) self.path_args = [self.decode_argument(arg) for arg in args] self.path_kwargs = dict( (k, self.decode_argument(v, name=k)) for (k, v) in kwargs.items() ) # If XSRF cookies are turned on, reject form submissions without # the proper cookie if self.request.method not in ( "GET", "HEAD", "OPTIONS", ) and self.application.settings.get("xsrf_cookies"): self.check_xsrf_cookie() result = self.prepare() if result is not None: result = await result # type: ignore if self._prepared_future is not None: # Tell the Application we've finished with prepare() # and are ready for the body to arrive. future_set_result_unless_cancelled(self._prepared_future, None) if self._finished: return if _has_stream_request_body(self.__class__): # In streaming mode request.body is a Future that signals # the body has been completely received. The Future has no # result; the data has been passed to self.data_received # instead. try: await self.request._body_future except iostream.StreamClosedError: return method = getattr(self, self.request.method.lower()) result = method(*self.path_args, **self.path_kwargs) if result is not None: result = await result if self._auto_finish and not self._finished: self.finish() except Exception as e: try: self._handle_request_exception(e) except Exception: app_log.error("Exception in exception handler", exc_info=True) finally: # Unset result to avoid circular references result = None if self._prepared_future is not None and not self._prepared_future.done(): # In case we failed before setting _prepared_future, do it # now (to unblock the HTTP server). Note that this is not # in a finally block to avoid GC issues prior to Python 3.4. self._prepared_future.set_result(None)
[docs] def data_received(self, chunk: bytes) -> Optional[Awaitable[None]]: """Implement this method to handle streamed request data. Requires the `.stream_request_body` decorator. May be a coroutine for flow control. """ raise NotImplementedError()
def _log(self) -> None: """Logs the current request. Sort of deprecated since this functionality was moved to the Application, but left in place for the benefit of existing apps that have overridden this method. """ self.application.log_request(self) def _request_summary(self) -> str: return "%s %s (%s)" % ( self.request.method, self.request.uri, self.request.remote_ip, ) def _handle_request_exception(self, e: BaseException) -> None: if isinstance(e, Finish): # Not an error; just finish the request without logging. if not self._finished: self.finish(*e.args) return try: self.log_exception(*sys.exc_info()) except Exception: # An error here should still get a best-effort send_error() # to avoid leaking the connection. app_log.error("Error in exception logger", exc_info=True) if self._finished: # Extra errors after the request has been finished should # be logged, but there is no reason to continue to try and # send a response. return if isinstance(e, HTTPError): self.send_error(e.status_code, exc_info=sys.exc_info()) else: self.send_error(500, exc_info=sys.exc_info())
[docs] def log_exception( self, typ: "Optional[Type[BaseException]]", value: Optional[BaseException], tb: Optional[TracebackType], ) -> None: """Override to customize logging of uncaught exceptions. By default logs instances of `HTTPError` as warnings without stack traces (on the ``tornado.general`` logger), and all other exceptions as errors with stack traces (on the ``tornado.application`` logger). .. versionadded:: 3.1 """ if isinstance(value, HTTPError): if value.log_message: format = "%d %s: " + value.log_message args = [value.status_code, self._request_summary()] + list(value.args) gen_log.warning(format, *args) else: app_log.error( "Uncaught exception %s\n%r", self._request_summary(), self.request, exc_info=(typ, value, tb), # type: ignore )
def _ui_module(self, name: str, module: Type["UIModule"]) -> Callable[..., str]: def render(*args, **kwargs) -> str: # type: ignore if not hasattr(self, "_active_modules"): self._active_modules = {} # type: Dict[str, UIModule] if name not in self._active_modules: self._active_modules[name] = module(self) rendered = self._active_modules[name].render(*args, **kwargs) return rendered return render def _ui_method(self, method: Callable[..., str]) -> Callable[..., str]: return lambda *args, **kwargs: method(self, *args, **kwargs) def _clear_representation_headers(self) -> None: # 304 responses should not contain representation metadata # headers (defined in # # not explicitly allowed by # headers = ["Content-Encoding", "Content-Language", "Content-Type"] for h in headers: self.clear_header(h)
_RequestHandlerType = TypeVar("_RequestHandlerType", bound=RequestHandler)
[docs]def stream_request_body(cls: Type[_RequestHandlerType]) -> Type[_RequestHandlerType]: """Apply to `RequestHandler` subclasses to enable streaming body support. This decorator implies the following changes: * `.HTTPServerRequest.body` is undefined, and body arguments will not be included in `RequestHandler.get_argument`. * `RequestHandler.prepare` is called when the request headers have been read instead of after the entire body has been read. * The subclass must define a method ``data_received(self, data):``, which will be called zero or more times as data is available. Note that if the request has an empty body, ``data_received`` may not be called. * ``prepare`` and ``data_received`` may return Futures (such as via ``@gen.coroutine``, in which case the next method will not be called until those futures have completed. * The regular HTTP method (``post``, ``put``, etc) will be called after the entire body has been read. See the `file receiver demo <>`_ for example usage. """ # noqa: E501 if not issubclass(cls, RequestHandler): raise TypeError("expected subclass of RequestHandler, got %r", cls) cls._stream_request_body = True return cls
def _has_stream_request_body(cls: Type[RequestHandler]) -> bool: if not issubclass(cls, RequestHandler): raise TypeError("expected subclass of RequestHandler, got %r", cls) return cls._stream_request_body
[docs]def removeslash( method: Callable[..., Optional[Awaitable[None]]] ) -> Callable[..., Optional[Awaitable[None]]]: """Use this decorator to remove trailing slashes from the request path. For example, a request to ``/foo/`` would redirect to ``/foo`` with this decorator. Your request handler mapping should use a regular expression like ``r'/foo/*'`` in conjunction with using the decorator. """ @functools.wraps(method) def wrapper( # type: ignore self: RequestHandler, *args, **kwargs ) -> Optional[Awaitable[None]]: if self.request.path.endswith("/"): if self.request.method in ("GET", "HEAD"): uri = self.request.path.rstrip("/") if uri: # don't try to redirect '/' to '' if self.request.query: uri += "?" + self.request.query self.redirect(uri, permanent=True) return None else: raise HTTPError(404) return method(self, *args, **kwargs) return wrapper
[docs]def addslash( method: Callable[..., Optional[Awaitable[None]]] ) -> Callable[..., Optional[Awaitable[None]]]: """Use this decorator to add a missing trailing slash to the request path. For example, a request to ``/foo`` would redirect to ``/foo/`` with this decorator. Your request handler mapping should use a regular expression like ``r'/foo/?'`` in conjunction with using the decorator. """ @functools.wraps(method) def wrapper( # type: ignore self: RequestHandler, *args, **kwargs ) -> Optional[Awaitable[None]]: if not self.request.path.endswith("/"): if self.request.method in ("GET", "HEAD"): uri = self.request.path + "/" if self.request.query: uri += "?" + self.request.query self.redirect(uri, permanent=True) return None raise HTTPError(404) return method(self, *args, **kwargs) return wrapper
class _ApplicationRouter(ReversibleRuleRouter): """Routing implementation used internally by `Application`. Provides a binding between `Application` and `RequestHandler`. This implementation extends `~.routing.ReversibleRuleRouter` in a couple of ways: * it allows to use `RequestHandler` subclasses as `~.routing.Rule` target and * it allows to use a list/tuple of rules as `~.routing.Rule` target. ``process_rule`` implementation will substitute this list with an appropriate `_ApplicationRouter` instance. """ def __init__( self, application: "Application", rules: Optional[_RuleList] = None ) -> None: assert isinstance(application, Application) self.application = application super().__init__(rules) def process_rule(self, rule: Rule) -> Rule: rule = super().process_rule(rule) if isinstance(, (list, tuple)): = _ApplicationRouter( self.application, # type: ignore ) return rule def get_target_delegate( self, target: Any, request: httputil.HTTPServerRequest, **target_params: Any ) -> Optional[httputil.HTTPMessageDelegate]: if isclass(target) and issubclass(target, RequestHandler): return self.application.get_handler_delegate( request, target, **target_params ) return super().get_target_delegate(target, request, **target_params)
[docs]class Application(ReversibleRouter): r"""A collection of request handlers that make up a web application. Instances of this class are callable and can be passed directly to HTTPServer to serve the application:: application = web.Application([ (r"/", MainPageHandler), ]) http_server = httpserver.HTTPServer(application) http_server.listen(8080) The constructor for this class takes in a list of `~.routing.Rule` objects or tuples of values corresponding to the arguments of `~.routing.Rule` constructor: ``(matcher, target, [target_kwargs], [name])``, the values in square brackets being optional. The default matcher is `~.routing.PathMatches`, so ``(regexp, target)`` tuples can also be used instead of ``(PathMatches(regexp), target)``. A common routing target is a `RequestHandler` subclass, but you can also use lists of rules as a target, which create a nested routing configuration:: application = web.Application([ (HostMatches(""), [ (r"/", MainPageHandler), (r"/feed", FeedHandler), ]), ]) In addition to this you can use nested `~.routing.Router` instances, `~.httputil.HTTPMessageDelegate` subclasses and callables as routing targets (see `~.routing` module docs for more information). When we receive requests, we iterate over the list in order and instantiate an instance of the first request class whose regexp matches the request path. The request class can be specified as either a class object or a (fully-qualified) name. A dictionary may be passed as the third element (``target_kwargs``) of the tuple, which will be used as keyword arguments to the handler's constructor and `~RequestHandler.initialize` method. This pattern is used for the `StaticFileHandler` in this example (note that a `StaticFileHandler` can be installed automatically with the static_path setting described below):: application = web.Application([ (r"/static/(.*)", web.StaticFileHandler, {"path": "/var/www"}), ]) We support virtual hosts with the `add_handlers` method, which takes in a host regular expression as the first argument:: application.add_handlers(r"www\.myhost\.com", [ (r"/article/([0-9]+)", ArticleHandler), ]) If there's no match for the current request's host, then ``default_host`` parameter value is matched against host regular expressions. .. warning:: Applications that do not use TLS may be vulnerable to :ref:`DNS rebinding <dnsrebinding>` attacks. This attack is especially relevant to applications that only listen on ```` or other private networks. Appropriate host patterns must be used (instead of the default of ``r'.*'``) to prevent this risk. The ``default_host`` argument must not be used in applications that may be vulnerable to DNS rebinding. You can serve static files by sending the ``static_path`` setting as a keyword argument. We will serve those files from the ``/static/`` URI (this is configurable with the ``static_url_prefix`` setting), and we will serve ``/favicon.ico`` and ``/robots.txt`` from the same directory. A custom subclass of `StaticFileHandler` can be specified with the ``static_handler_class`` setting. .. versionchanged:: 4.5 Integration with the new `tornado.routing` module. """ def __init__( self, handlers: Optional[_RuleList] = None, default_host: Optional[str] = None, transforms: Optional[List[Type["OutputTransform"]]] = None, **settings: Any, ) -> None: if transforms is None: self.transforms = [] # type: List[Type[OutputTransform]] if settings.get("compress_response") or settings.get("gzip"): self.transforms.append(GZipContentEncoding) else: self.transforms = transforms self.default_host = default_host self.settings = settings self.ui_modules = { "linkify": _linkify, "xsrf_form_html": _xsrf_form_html, "Template": TemplateModule, } self.ui_methods = {} # type: Dict[str, Callable[..., str]] self._load_ui_modules(settings.get("ui_modules", {})) self._load_ui_methods(settings.get("ui_methods", {})) if self.settings.get("static_path"): path = self.settings["static_path"] handlers = list(handlers or []) static_url_prefix = settings.get("static_url_prefix", "/static/") static_handler_class = settings.get( "static_handler_class", StaticFileHandler ) static_handler_args = settings.get("static_handler_args", {}) static_handler_args["path"] = path for pattern in [ re.escape(static_url_prefix) + r"(.*)", r"/(favicon\.ico)", r"/(robots\.txt)", ]: handlers.insert(0, (pattern, static_handler_class, static_handler_args)) if self.settings.get("debug"): self.settings.setdefault("autoreload", True) self.settings.setdefault("compiled_template_cache", False) self.settings.setdefault("static_hash_cache", False) self.settings.setdefault("serve_traceback", True) self.wildcard_router = _ApplicationRouter(self, handlers) self.default_router = _ApplicationRouter( self, [Rule(AnyMatches(), self.wildcard_router)] ) # Automatically reload modified modules if self.settings.get("autoreload"): from tornado import autoreload autoreload.start()
[docs] def listen( self, port: int, address: Optional[str] = None, *, family: socket.AddressFamily = socket.AF_UNSPEC, backlog: int = tornado.netutil._DEFAULT_BACKLOG, flags: Optional[int] = None, reuse_port: bool = False, **kwargs: Any, ) -> HTTPServer: """Starts an HTTP server for this application on the given port. This is a convenience alias for creating an `.HTTPServer` object and calling its listen method. Keyword arguments not supported by `HTTPServer.listen <.TCPServer.listen>` are passed to the `.HTTPServer` constructor. For advanced uses (e.g. multi-process mode), do not use this method; create an `.HTTPServer` and call its `.TCPServer.bind`/`.TCPServer.start` methods directly. Note that after calling this method you still need to call ``IOLoop.current().start()`` (or run within ````) to start the server. Returns the `.HTTPServer` object. .. versionchanged:: 4.3 Now returns the `.HTTPServer` object. .. versionchanged:: 6.2 Added support for new keyword arguments in `.TCPServer.listen`, including ``reuse_port``. """ server = HTTPServer(self, **kwargs) server.listen( port, address=address, family=family, backlog=backlog, flags=flags, reuse_port=reuse_port, ) return server
[docs] def add_handlers(self, host_pattern: str, host_handlers: _RuleList) -> None: """Appends the given handlers to our handler list. Host patterns are processed sequentially in the order they were added. All matching patterns will be considered. """ host_matcher = HostMatches(host_pattern) rule = Rule(host_matcher, _ApplicationRouter(self, host_handlers)) self.default_router.rules.insert(-1, rule) if self.default_host is not None: self.wildcard_router.add_rules( [(DefaultHostMatches(self, host_matcher.host_pattern), host_handlers)] )
def add_transform(self, transform_class: Type["OutputTransform"]) -> None: self.transforms.append(transform_class) def _load_ui_methods(self, methods: Any) -> None: if isinstance(methods, types.ModuleType): self._load_ui_methods(dict((n, getattr(methods, n)) for n in dir(methods))) elif isinstance(methods, list): for m in methods: self._load_ui_methods(m) else: for name, fn in methods.items(): if ( not name.startswith("_") and hasattr(fn, "__call__") and name[0].lower() == name[0] ): self.ui_methods[name] = fn def _load_ui_modules(self, modules: Any) -> None: if isinstance(modules, types.ModuleType): self._load_ui_modules(dict((n, getattr(modules, n)) for n in dir(modules))) elif isinstance(modules, list): for m in modules: self._load_ui_modules(m) else: assert isinstance(modules, dict) for name, cls in modules.items(): try: if issubclass(cls, UIModule): self.ui_modules[name] = cls except TypeError: pass def __call__( self, request: httputil.HTTPServerRequest ) -> Optional[Awaitable[None]]: # Legacy HTTPServer interface dispatcher = self.find_handler(request) return dispatcher.execute() def find_handler( self, request: httputil.HTTPServerRequest, **kwargs: Any ) -> "_HandlerDelegate": route = self.default_router.find_handler(request) if route is not None: return cast("_HandlerDelegate", route) if self.settings.get("default_handler_class"): return self.get_handler_delegate( request, self.settings["default_handler_class"], self.settings.get("default_handler_args", {}), ) return self.get_handler_delegate(request, ErrorHandler, {"status_code": 404})
[docs] def get_handler_delegate( self, request: httputil.HTTPServerRequest, target_class: Type[RequestHandler], target_kwargs: Optional[Dict[str, Any]] = None, path_args: Optional[List[bytes]] = None, path_kwargs: Optional[Dict[str, bytes]] = None, ) -> "_HandlerDelegate": """Returns `~.httputil.HTTPMessageDelegate` that can serve a request for application and `RequestHandler` subclass. :arg httputil.HTTPServerRequest request: current HTTP request. :arg RequestHandler target_class: a `RequestHandler` class. :arg dict target_kwargs: keyword arguments for ``target_class`` constructor. :arg list path_args: positional arguments for ``target_class`` HTTP method that will be executed while handling a request (``get``, ``post`` or any other). :arg dict path_kwargs: keyword arguments for ``target_class`` HTTP method. """ return _HandlerDelegate( self, request, target_class, target_kwargs, path_args, path_kwargs )
[docs] def reverse_url(self, name: str, *args: Any) -> str: """Returns a URL path for handler named ``name`` The handler must be added to the application as a named `URLSpec`. Args will be substituted for capturing groups in the `URLSpec` regex. They will be converted to strings if necessary, encoded as utf8, and url-escaped. """ reversed_url = self.default_router.reverse_url(name, *args) if reversed_url is not None: return reversed_url raise KeyError("%s not found in named urls" % name)
[docs] def log_request(self, handler: RequestHandler) -> None: """Writes a completed HTTP request to the logs. By default writes to the python root logger. To change this behavior either subclass Application and override this method, or pass a function in the application settings dictionary as ``log_function``. """ if "log_function" in self.settings: self.settings["log_function"](handler) return if handler.get_status() < 400: log_method = elif handler.get_status() < 500: log_method = access_log.warning else: log_method = access_log.error request_time = 1000.0 * handler.request.request_time() log_method( "%d %s %.2fms", handler.get_status(), handler._request_summary(), request_time, )
class _HandlerDelegate(httputil.HTTPMessageDelegate): def __init__( self, application: Application, request: httputil.HTTPServerRequest, handler_class: Type[RequestHandler], handler_kwargs: Optional[Dict[str, Any]], path_args: Optional[List[bytes]], path_kwargs: Optional[Dict[str, bytes]], ) -> None: self.application = application self.connection = request.connection self.request = request self.handler_class = handler_class self.handler_kwargs = handler_kwargs or {} self.path_args = path_args or [] self.path_kwargs = path_kwargs or {} self.chunks = [] # type: List[bytes] self.stream_request_body = _has_stream_request_body(self.handler_class) def headers_received( self, start_line: Union[httputil.RequestStartLine, httputil.ResponseStartLine], headers: httputil.HTTPHeaders, ) -> Optional[Awaitable[None]]: if self.stream_request_body: self.request._body_future = Future() return self.execute() return None def data_received(self, data: bytes) -> Optional[Awaitable[None]]: if self.stream_request_body: return self.handler.data_received(data) else: self.chunks.append(data) return None def finish(self) -> None: if self.stream_request_body: future_set_result_unless_cancelled(self.request._body_future, None) else: self.request.body = b"".join(self.chunks) self.request._parse_body() self.execute() def on_connection_close(self) -> None: if self.stream_request_body: self.handler.on_connection_close() else: self.chunks = None # type: ignore def execute(self) -> Optional[Awaitable[None]]: # If template cache is disabled (usually in the debug mode), # re-compile templates and reload static files on every # request so you don't need to restart to see changes if not self.application.settings.get("compiled_template_cache", True): with RequestHandler._template_loader_lock: for loader in RequestHandler._template_loaders.values(): loader.reset() if not self.application.settings.get("static_hash_cache", True): static_handler_class = self.application.settings.get( "static_handler_class", StaticFileHandler ) static_handler_class.reset() self.handler = self.handler_class( self.application, self.request, **self.handler_kwargs ) transforms = [t(self.request) for t in self.application.transforms] if self.stream_request_body: self.handler._prepared_future = Future() # Note that if an exception escapes handler._execute it will be # trapped in the Future it returns (which we are ignoring here, # leaving it to be logged when the Future is GC'd). # However, that shouldn't happen because _execute has a blanket # except handler, and we cannot easily access the IOLoop here to # call add_future (because of the requirement to remain compatible # with WSGI) fut = gen.convert_yielded( self.handler._execute(transforms, *self.path_args, **self.path_kwargs) ) fut.add_done_callback(lambda f: f.result()) # If we are streaming the request body, then execute() is finished # when the handler has prepared to receive the body. If not, # it doesn't matter when execute() finishes (so we return None) return self.handler._prepared_future
[docs]class HTTPError(Exception): """An exception that will turn into an HTTP error response. Raising an `HTTPError` is a convenient alternative to calling `RequestHandler.send_error` since it automatically ends the current function. To customize the response sent with an `HTTPError`, override `RequestHandler.write_error`. :arg int status_code: HTTP status code. Must be listed in `httplib.responses <http.client.responses>` unless the ``reason`` keyword argument is given. :arg str log_message: Message to be written to the log for this error (will not be shown to the user unless the `Application` is in debug mode). May contain ``%s``-style placeholders, which will be filled in with remaining positional parameters. :arg str reason: Keyword-only argument. The HTTP "reason" phrase to pass in the status line along with ``status_code``. Normally determined automatically from ``status_code``, but can be used to use a non-standard numeric code. """ def __init__( self, status_code: int = 500, log_message: Optional[str] = None, *args: Any, **kwargs: Any, ) -> None: self.status_code = status_code self.log_message = log_message self.args = args self.reason = kwargs.get("reason", None) if log_message and not args: self.log_message = log_message.replace("%", "%%") def __str__(self) -> str: message = "HTTP %d: %s" % ( self.status_code, self.reason or httputil.responses.get(self.status_code, "Unknown"), ) if self.log_message: return message + " (" + (self.log_message % self.args) + ")" else: return message
[docs]class Finish(Exception): """An exception that ends the request without producing an error response. When `Finish` is raised in a `RequestHandler`, the request will end (calling `RequestHandler.finish` if it hasn't already been called), but the error-handling methods (including `RequestHandler.write_error`) will not be called. If `Finish()` was created with no arguments, the pending response will be sent as-is. If `Finish()` was given an argument, that argument will be passed to `RequestHandler.finish()`. This can be a more convenient way to implement custom error pages than overriding ``write_error`` (especially in library code):: if self.current_user is None: self.set_status(401) self.set_header('WWW-Authenticate', 'Basic realm="something"') raise Finish() .. versionchanged:: 4.3 Arguments passed to ``Finish()`` will be passed on to `RequestHandler.finish`. """ pass
[docs]class MissingArgumentError(HTTPError): """Exception raised by `RequestHandler.get_argument`. This is a subclass of `HTTPError`, so if it is uncaught a 400 response code will be used instead of 500 (and a stack trace will not be logged). .. versionadded:: 3.1 """ def __init__(self, arg_name: str) -> None: super().__init__(400, "Missing argument %s" % arg_name) self.arg_name = arg_name
[docs]class ErrorHandler(RequestHandler): """Generates an error response with ``status_code`` for all requests.""" def initialize(self, status_code: int) -> None: self.set_status(status_code) def prepare(self) -> None: raise HTTPError(self._status_code) def check_xsrf_cookie(self) -> None: # POSTs to an ErrorHandler don't actually have side effects, # so we don't need to check the xsrf token. This allows POSTs # to the wrong url to return a 404 instead of 403. pass
[docs]class RedirectHandler(RequestHandler): """Redirects the client to the given URL for all GET requests. You should provide the keyword argument ``url`` to the handler, e.g.:: application = web.Application([ (r"/oldpath", web.RedirectHandler, {"url": "/newpath"}), ]) `RedirectHandler` supports regular expression substitutions. E.g., to swap the first and second parts of a path while preserving the remainder:: application = web.Application([ (r"/(.*?)/(.*?)/(.*)", web.RedirectHandler, {"url": "/{1}/{0}/{2}"}), ]) The final URL is formatted with `str.format` and the substrings that match the capturing groups. In the above example, a request to "/a/b/c" would be formatted like:: str.format("/{1}/{0}/{2}", "a", "b", "c") # -> "/b/a/c" Use Python's :ref:`format string syntax <formatstrings>` to customize how values are substituted. .. versionchanged:: 4.5 Added support for substitutions into the destination URL. .. versionchanged:: 5.0 If any query arguments are present, they will be copied to the destination URL. """ def initialize(self, url: str, permanent: bool = True) -> None: self._url = url self._permanent = permanent def get(self, *args: Any, **kwargs: Any) -> None: to_url = self._url.format(*args, **kwargs) if self.request.query_arguments: # TODO: figure out typing for the next line. to_url = httputil.url_concat( to_url, list(httputil.qs_to_qsl(self.request.query_arguments)), # type: ignore ) self.redirect(to_url, permanent=self._permanent)
[docs]class StaticFileHandler(RequestHandler): """A simple handler that can serve static content from a directory. A `StaticFileHandler` is configured automatically if you pass the ``static_path`` keyword argument to `Application`. This handler can be customized with the ``static_url_prefix``, ``static_handler_class``, and ``static_handler_args`` settings. To map an additional path to this handler for a static data directory you would add a line to your application like:: application = web.Application([ (r"/content/(.*)", web.StaticFileHandler, {"path": "/var/www"}), ]) The handler constructor requires a ``path`` argument, which specifies the local root directory of the content to be served. Note that a capture group in the regex is required to parse the value for the ``path`` argument to the get() method (different than the constructor argument above); see `URLSpec` for details. To serve a file like ``index.html`` automatically when a directory is requested, set ``static_handler_args=dict(default_filename="index.html")`` in your application settings, or add ``default_filename`` as an initializer argument for your ``StaticFileHandler``. To maximize the effectiveness of browser caching, this class supports versioned urls (by default using the argument ``?v=``). If a version is given, we instruct the browser to cache this file indefinitely. `make_static_url` (also available as `RequestHandler.static_url`) can be used to construct a versioned url. This handler is intended primarily for use in development and light-duty file serving; for heavy traffic it will be more efficient to use a dedicated static file server (such as nginx or Apache). We support the HTTP ``Accept-Ranges`` mechanism to return partial content (because some browsers require this functionality to be present to seek in HTML5 audio or video). **Subclassing notes** This class is designed to be extensible by subclassing, but because of the way static urls are generated with class methods rather than instance methods, the inheritance patterns are somewhat unusual. Be sure to use the ``@classmethod`` decorator when overriding a class method. Instance methods may use the attributes ``self.path`` ``self.absolute_path``, and ``self.modified``. Subclasses should only override methods discussed in this section; overriding other methods is error-prone. Overriding ``StaticFileHandler.get`` is particularly problematic due to the tight coupling with ``compute_etag`` and other methods. To change the way static urls are generated (e.g. to match the behavior of another server or CDN), override `make_static_url`, `parse_url_path`, `get_cache_time`, and/or `get_version`. To replace all interaction with the filesystem (e.g. to serve static content from a database), override `get_content`, `get_content_size`, `get_modified_time`, `get_absolute_path`, and `validate_absolute_path`. .. versionchanged:: 3.1 Many of the methods for subclasses were added in Tornado 3.1. """ CACHE_MAX_AGE = 86400 * 365 * 10 # 10 years _static_hashes = {} # type: Dict[str, Optional[str]] _lock = threading.Lock() # protects _static_hashes def initialize(self, path: str, default_filename: Optional[str] = None) -> None: self.root = path self.default_filename = default_filename @classmethod def reset(cls) -> None: with cls._lock: cls._static_hashes = {} def head(self, path: str) -> Awaitable[None]: return self.get(path, include_body=False) async def get(self, path: str, include_body: bool = True) -> None: # Set up our path instance variables. self.path = self.parse_url_path(path) del path # make sure we don't refer to path instead of self.path again absolute_path = self.get_absolute_path(self.root, self.path) self.absolute_path = self.validate_absolute_path(self.root, absolute_path) if self.absolute_path is None: return self.modified = self.get_modified_time() self.set_headers() if self.should_return_304(): self.set_status(304) return request_range = None range_header = self.request.headers.get("Range") if range_header: # As per RFC 2616 14.16, if an invalid Range header is specified, # the request will be treated as if the header didn't exist. request_range = httputil._parse_request_range(range_header) size = self.get_content_size() if request_range: start, end = request_range if start is not None and start < 0: start += size if start < 0: start = 0 if ( start is not None and (start >= size or (end is not None and start >= end)) ) or end == 0: # As per RFC 2616 14.35.1, a range is not satisfiable only: if # the first requested byte is equal to or greater than the # content, or when a suffix with length 0 is specified. # # A byte-range-spec is invalid if the last-byte-pos value is present # and less than the first-byte-pos. self.set_status(416) # Range Not Satisfiable self.set_header("Content-Type", "text/plain") self.set_header("Content-Range", "bytes */%s" % (size,)) return if end is not None and end > size: # Clients sometimes blindly use a large range to limit their # download size; cap the endpoint at the actual file size. end = size # Note: only return HTTP 206 if less than the entire range has been # requested. Not only is this semantically correct, but Chrome # refuses to play audio if it gets an HTTP 206 in response to # ``Range: bytes=0-``. if size != (end or size) - (start or 0): self.set_status(206) # Partial Content self.set_header( "Content-Range", httputil._get_content_range(start, end, size) ) else: start = end = None if start is not None and end is not None: content_length = end - start elif end is not None: content_length = end elif start is not None: content_length = size - start else: content_length = size self.set_header("Content-Length", content_length) if include_body: content = self.get_content(self.absolute_path, start, end) if isinstance(content, bytes): content = [content] for chunk in content: try: self.write(chunk) await self.flush() except iostream.StreamClosedError: return else: assert self.request.method == "HEAD"
[docs] def compute_etag(self) -> Optional[str]: """Sets the ``Etag`` header based on static url version. This allows efficient ``If-None-Match`` checks against cached versions, and sends the correct ``Etag`` for a partial response (i.e. the same ``Etag`` as the full file). .. versionadded:: 3.1 """ assert self.absolute_path is not None version_hash = self._get_cached_version(self.absolute_path) if not version_hash: return None return '"%s"' % (version_hash,)
[docs] def set_headers(self) -> None: """Sets the content and caching headers on the response. .. versionadded:: 3.1 """ self.set_header("Accept-Ranges", "bytes") self.set_etag_header() if self.modified is not None: self.set_header("Last-Modified", self.modified) content_type = self.get_content_type() if content_type: self.set_header("Content-Type", content_type) cache_time = self.get_cache_time(self.path, self.modified, content_type) if cache_time > 0: self.set_header( "Expires", + datetime.timedelta(seconds=cache_time), ) self.set_header("Cache-Control", "max-age=" + str(cache_time)) self.set_extra_headers(self.path)
[docs] def should_return_304(self) -> bool: """Returns True if the headers indicate that we should return 304. .. versionadded:: 3.1 """ # If client sent If-None-Match, use it, ignore If-Modified-Since if self.request.headers.get("If-None-Match"): return self.check_etag_header() # 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: if_since = email.utils.parsedate_to_datetime(ims_value) if if_since.tzinfo is None: if_since = if_since.replace(tzinfo=datetime.timezone.utc) assert self.modified is not None if if_since >= self.modified: return True return False
[docs] @classmethod def get_absolute_path(cls, root: str, path: str) -> str: """Returns the absolute location of ``path`` relative to ``root``. ``root`` is the path configured for this `StaticFileHandler` (in most cases the ``static_path`` `Application` setting). This class method may be overridden in subclasses. By default it returns a filesystem path, but other strings may be used as long as they are unique and understood by the subclass's overridden `get_content`. .. versionadded:: 3.1 """ abspath = os.path.abspath(os.path.join(root, path)) return abspath
[docs] def validate_absolute_path(self, root: str, absolute_path: str) -> Optional[str]: """Validate and return the absolute path. ``root`` is the configured path for the `StaticFileHandler`, and ``path`` is the result of `get_absolute_path` This is an instance method called during request processing, so it may raise `HTTPError` or use methods like `RequestHandler.redirect` (return None after redirecting to halt further processing). This is where 404 errors for missing files are generated. This method may modify the path before returning it, but note that any such modifications will not be understood by `make_static_url`. In instance methods, this method's result is available as ``self.absolute_path``. .. versionadded:: 3.1 """ # os.path.abspath strips a trailing /. # We must add it back to `root` so that we only match files # in a directory named `root` instead of files starting with # that prefix. root = os.path.abspath(root) if not root.endswith(os.path.sep): # abspath always removes a trailing slash, except when # root is '/'. This is an unusual case, but several projects # have independently discovered this technique to disable # Tornado's path validation and (hopefully) do their own, # so we need to support it. root += os.path.sep # The trailing slash also needs to be temporarily added back # the requested path so a request to root/ will match. if not (absolute_path + os.path.sep).startswith(root): raise HTTPError(403, "%s is not in root static directory", self.path) if os.path.isdir(absolute_path) 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("/"): if self.request.path.startswith("//"): # A redirect with two initial slashes is a "protocol-relative" URL. # This means the next path segment is treated as a hostname instead # of a part of the path, making this effectively an open redirect. # Reject paths starting with two slashes to prevent this. # This is only reachable under certain configurations. raise HTTPError( 403, "cannot redirect path with two initial slashes" ) self.redirect(self.request.path + "/", permanent=True) return None absolute_path = os.path.join(absolute_path, self.default_filename) if not os.path.exists(absolute_path): raise HTTPError(404) if not os.path.isfile(absolute_path): raise HTTPError(403, "%s is not a file", self.path) return absolute_path
[docs] @classmethod def get_content( cls, abspath: str, start: Optional[int] = None, end: Optional[int] = None ) -> Generator[bytes, None, None]: """Retrieve the content of the requested resource which is located at the given absolute path. This class method may be overridden by subclasses. Note that its signature is different from other overridable class methods (no ``settings`` argument); this is deliberate to ensure that ``abspath`` is able to stand on its own as a cache key. This method should either return a byte string or an iterator of byte strings. The latter is preferred for large files as it helps reduce memory fragmentation. .. versionadded:: 3.1 """ with open(abspath, "rb") as file: if start is not None: if end is not None: remaining = end - (start or 0) # type: Optional[int] else: remaining = None while True: chunk_size = 64 * 1024 if remaining is not None and remaining < chunk_size: chunk_size = remaining chunk = if chunk: if remaining is not None: remaining -= len(chunk) yield chunk else: if remaining is not None: assert remaining == 0 return
[docs] @classmethod def get_content_version(cls, abspath: str) -> str: """Returns a version string for the resource at the given path. This class method may be overridden by subclasses. The default implementation is a SHA-512 hash of the file's contents. .. versionadded:: 3.1 """ data = cls.get_content(abspath) hasher = hashlib.sha512() if isinstance(data, bytes): hasher.update(data) else: for chunk in data: hasher.update(chunk) return hasher.hexdigest()
def _stat(self) -> os.stat_result: assert self.absolute_path is not None if not hasattr(self, "_stat_result"): self._stat_result = os.stat(self.absolute_path) return self._stat_result
[docs] def get_content_size(self) -> int: """Retrieve the total size of the resource at the given path. This method may be overridden by subclasses. .. versionadded:: 3.1 .. versionchanged:: 4.0 This method is now always called, instead of only when partial results are requested. """ stat_result = self._stat() return stat_result.st_size
[docs] def get_modified_time(self) -> Optional[datetime.datetime]: """Returns the time that ``self.absolute_path`` was last modified. May be overridden in subclasses. Should return a `~datetime.datetime` object or None. .. versionadded:: 3.1 .. versionchanged:: 6.4 Now returns an aware datetime object instead of a naive one. Subclasses that override this method may return either kind. """ stat_result = self._stat() # NOTE: Historically, this used stat_result[stat.ST_MTIME], # which truncates the fractional portion of the timestamp. It # was changed from that form to stat_result.st_mtime to # satisfy mypy (which disallows the bracket operator), but the # latter form returns a float instead of an int. For # consistency with the past (and because we have a unit test # that relies on this), we truncate the float here, although # I'm not sure that's the right thing to do. modified = datetime.datetime.fromtimestamp( int(stat_result.st_mtime), datetime.timezone.utc ) return modified
[docs] def get_content_type(self) -> str: """Returns the ``Content-Type`` header to be used for this request. .. versionadded:: 3.1 """ assert self.absolute_path is not None mime_type, encoding = mimetypes.guess_type(self.absolute_path) # per RFC 6713, use the appropriate type for a gzip compressed file if encoding == "gzip": return "application/gzip" # As of 2015-07-21 there is no bzip2 encoding defined at # # So for that (and any other encoding), use octet-stream. elif encoding is not None: return "application/octet-stream" elif mime_type is not None: return mime_type # if mime_type not detected, use application/octet-stream else: return "application/octet-stream"
[docs] def set_extra_headers(self, path: str) -> None: """For subclass to add extra headers to the response""" pass
[docs] def get_cache_time( self, path: str, modified: Optional[datetime.datetime], mime_type: str ) -> int: """Override to customize cache control behavior. Return a positive number of seconds to make the result cacheable for that amount of time or 0 to mark resource as cacheable for an unspecified amount of time (subject to browser heuristics). By default returns cache expiry of 10 years for resources requested with ``v`` argument. """ return self.CACHE_MAX_AGE if "v" in self.request.arguments else 0
[docs] @classmethod def make_static_url( cls, settings: Dict[str, Any], path: str, include_version: bool = True ) -> str: """Constructs a versioned url for the given path. This method may be overridden in subclasses (but note that it is a class method rather than an instance method). Subclasses are only required to implement the signature ``make_static_url(cls, settings, path)``; other keyword arguments may be passed through `~RequestHandler.static_url` but are not standard. ``settings`` is the `Application.settings` dictionary. ``path`` is the static path being requested. The url returned should be relative to the current host. ``include_version`` determines whether the generated URL should include the query string containing the version hash of the file corresponding to the given ``path``. """ url = settings.get("static_url_prefix", "/static/") + path if not include_version: return url version_hash = cls.get_version(settings, path) if not version_hash: return url return "%s?v=%s" % (url, version_hash)
[docs] def parse_url_path(self, url_path: str) -> str: """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``. This is the inverse of `make_static_url`. """ if os.path.sep != "/": url_path = url_path.replace("/", os.path.sep) return url_path
[docs] @classmethod def get_version(cls, settings: Dict[str, Any], path: str) -> Optional[str]: """Generate the version string to be used in static URLs. ``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. .. versionchanged:: 3.1 This method was previously recommended for subclasses to override; `get_content_version` is now preferred as it allows the base class to handle caching of the result. """ abs_path = cls.get_absolute_path(settings["static_path"], path) return cls._get_cached_version(abs_path)
@classmethod def _get_cached_version(cls, abs_path: str) -> Optional[str]: with cls._lock: hashes = cls._static_hashes if abs_path not in hashes: try: hashes[abs_path] = cls.get_content_version(abs_path) except Exception: gen_log.error("Could not open static file %r", abs_path) hashes[abs_path] = None hsh = hashes.get(abs_path) if hsh: return hsh return None
[docs]class FallbackHandler(RequestHandler): """A `RequestHandler` that wraps another HTTP server callback. The fallback is a callable object that accepts an `~.httputil.HTTPServerRequest`, such as an `Application` or `tornado.wsgi.WSGIContainer`. This is most useful to use both Tornado ``RequestHandlers`` and WSGI in the same server. Typical usage:: wsgi_app = tornado.wsgi.WSGIContainer( django.core.handlers.wsgi.WSGIHandler()) application = tornado.web.Application([ (r"/foo", FooHandler), (r".*", FallbackHandler, dict(fallback=wsgi_app)), ]) """ def initialize( self, fallback: Callable[[httputil.HTTPServerRequest], None] ) -> None: self.fallback = fallback def prepare(self) -> None: self.fallback(self.request) self._finished = True self.on_finish()
class OutputTransform(object): """A transform modifies the result of an HTTP request (e.g., GZip encoding) Applications are not expected to create their own OutputTransforms or interact with them directly; the framework chooses which transforms (if any) to apply. """ def __init__(self, request: httputil.HTTPServerRequest) -> None: pass def transform_first_chunk( self, status_code: int, headers: httputil.HTTPHeaders, chunk: bytes, finishing: bool, ) -> Tuple[int, httputil.HTTPHeaders, bytes]: return status_code, headers, chunk def transform_chunk(self, chunk: bytes, finishing: bool) -> bytes: return chunk class GZipContentEncoding(OutputTransform): """Applies the gzip content encoding to the response. See .. versionchanged:: 4.0 Now compresses all mime types beginning with ``text/``, instead of just a whitelist. (the whitelist is still used for certain non-text mime types). """ # Whitelist of compressible mime types (in addition to any types # beginning with "text/"). CONTENT_TYPES = set( [ "application/javascript", "application/x-javascript", "application/xml", "application/atom+xml", "application/json", "application/xhtml+xml", "image/svg+xml", ] ) # Python's GzipFile defaults to level 9, while most other gzip # tools (including gzip itself) default to 6, which is probably a # better CPU/size tradeoff. GZIP_LEVEL = 6 # Responses that are too short are unlikely to benefit from gzipping # after considering the "Content-Encoding: gzip" header and the header # inside the gzip encoding. # Note that responses written in multiple chunks will be compressed # regardless of size. MIN_LENGTH = 1024 def __init__(self, request: httputil.HTTPServerRequest) -> None: self._gzipping = "gzip" in request.headers.get("Accept-Encoding", "") def _compressible_type(self, ctype: str) -> bool: return ctype.startswith("text/") or ctype in self.CONTENT_TYPES def transform_first_chunk( self, status_code: int, headers: httputil.HTTPHeaders, chunk: bytes, finishing: bool, ) -> Tuple[int, httputil.HTTPHeaders, bytes]: # TODO: can/should this type be inherited from the superclass? if "Vary" in headers: headers["Vary"] += ", Accept-Encoding" else: headers["Vary"] = "Accept-Encoding" if self._gzipping: ctype = _unicode(headers.get("Content-Type", "")).split(";")[0] self._gzipping = ( self._compressible_type(ctype) and (not finishing or len(chunk) >= self.MIN_LENGTH) and ("Content-Encoding" not in headers) ) if self._gzipping: headers["Content-Encoding"] = "gzip" self._gzip_value = BytesIO() self._gzip_file = gzip.GzipFile( mode="w", fileobj=self._gzip_value, compresslevel=self.GZIP_LEVEL ) chunk = self.transform_chunk(chunk, finishing) if "Content-Length" in headers: # The original content length is no longer correct. # If this is the last (and only) chunk, we can set the new # content-length; otherwise we remove it and fall back to # chunked encoding. if finishing: headers["Content-Length"] = str(len(chunk)) else: del headers["Content-Length"] return status_code, headers, chunk def transform_chunk(self, chunk: bytes, finishing: bool) -> bytes: if self._gzipping: self._gzip_file.write(chunk) if finishing: self._gzip_file.close() else: self._gzip_file.flush() chunk = self._gzip_value.getvalue() self._gzip_value.truncate(0) return chunk
[docs]def authenticated( method: Callable[..., Optional[Awaitable[None]]] ) -> Callable[..., Optional[Awaitable[None]]]: """Decorate methods with this to require that the user be logged in. If the user is not logged in, they will be redirected to the configured `login url <RequestHandler.get_login_url>`. If you configure a login url with a query parameter, Tornado will assume you know what you're doing and use it as-is. If not, it will add a `next` parameter so the login page knows where to send you once you're logged in. """ @functools.wraps(method) def wrapper( # type: ignore self: RequestHandler, *args, **kwargs ) -> Optional[Awaitable[None]]: if not self.current_user: if self.request.method in ("GET", "HEAD"): url = self.get_login_url() if "?" not in url: if urllib.parse.urlsplit(url).scheme: # if login url is absolute, make next absolute too next_url = self.request.full_url() else: assert self.request.uri is not None next_url = self.request.uri url += "?" + urlencode(dict(next=next_url)) self.redirect(url) return None raise HTTPError(403) return method(self, *args, **kwargs) return wrapper
[docs]class UIModule(object): """A re-usable, modular UI unit on a page. UI modules often execute additional queries, and they can include additional CSS and JavaScript that will be included in the output page, which is automatically inserted on page render. Subclasses of UIModule must override the `render` method. """ def __init__(self, handler: RequestHandler) -> None: self.handler = handler self.request = handler.request self.ui = handler.ui self.locale = handler.locale @property def current_user(self) -> Any: return self.handler.current_user
[docs] def render(self, *args: Any, **kwargs: Any) -> str: """Override in subclasses to return this module's output.""" raise NotImplementedError()
[docs] def embedded_javascript(self) -> Optional[str]: """Override to return a JavaScript string to be embedded in the page.""" return None
[docs] def javascript_files(self) -> Optional[Iterable[str]]: """Override to return a list of JavaScript files needed by this module. If the return values are relative paths, they will be passed to `RequestHandler.static_url`; otherwise they will be used as-is. """ return None
[docs] def embedded_css(self) -> Optional[str]: """Override to return a CSS string that will be embedded in the page.""" return None
[docs] def css_files(self) -> Optional[Iterable[str]]: """Override to returns a list of CSS files required by this module. If the return values are relative paths, they will be passed to `RequestHandler.static_url`; otherwise they will be used as-is. """ return None
[docs] def html_head(self) -> Optional[str]: """Override to return an HTML string that will be put in the <head/> element. """ return None
[docs] def html_body(self) -> Optional[str]: """Override to return an HTML string that will be put at the end of the <body/> element. """ return None
[docs] def render_string(self, path: str, **kwargs: Any) -> bytes: """Renders a template and returns it as a string.""" return self.handler.render_string(path, **kwargs)
class _linkify(UIModule): def render(self, text: str, **kwargs: Any) -> str: # type: ignore return escape.linkify(text, **kwargs) class _xsrf_form_html(UIModule): def render(self) -> str: # type: ignore return self.handler.xsrf_form_html() class TemplateModule(UIModule): """UIModule that simply renders the given template. {% module Template("foo.html") %} is similar to {% include "foo.html" %}, but the module version gets its own namespace (with kwargs passed to Template()) instead of inheriting the outer template's namespace. Templates rendered through this module also get access to UIModule's automatic JavaScript/CSS features. Simply call set_resources inside the template and give it keyword arguments corresponding to the methods on UIModule: {{ set_resources(js_files=static_url("my.js")) }} Note that these resources are output once per template file, not once per instantiation of the template, so they must not depend on any arguments to the template. """ def __init__(self, handler: RequestHandler) -> None: super().__init__(handler) # keep resources in both a list and a dict to preserve order self._resource_list = [] # type: List[Dict[str, Any]] self._resource_dict = {} # type: Dict[str, Dict[str, Any]] def render(self, path: str, **kwargs: Any) -> bytes: # type: ignore def set_resources(**kwargs) -> str: # type: ignore if path not in self._resource_dict: self._resource_list.append(kwargs) self._resource_dict[path] = kwargs else: if self._resource_dict[path] != kwargs: raise ValueError( "set_resources called with different " "resources for the same template" ) return "" return self.render_string(path, set_resources=set_resources, **kwargs) def _get_resources(self, key: str) -> Iterable[str]: return (r[key] for r in self._resource_list if key in r) def embedded_javascript(self) -> str: return "\n".join(self._get_resources("embedded_javascript")) def javascript_files(self) -> Iterable[str]: result = [] for f in self._get_resources("javascript_files"): if isinstance(f, (unicode_type, bytes)): result.append(f) else: result.extend(f) return result def embedded_css(self) -> str: return "\n".join(self._get_resources("embedded_css")) def css_files(self) -> Iterable[str]: result = [] for f in self._get_resources("css_files"): if isinstance(f, (unicode_type, bytes)): result.append(f) else: result.extend(f) return result def html_head(self) -> str: return "".join(self._get_resources("html_head")) def html_body(self) -> str: return "".join(self._get_resources("html_body")) class _UIModuleNamespace(object): """Lazy namespace which creates UIModule proxies bound to a handler.""" def __init__( self, handler: RequestHandler, ui_modules: Dict[str, Type[UIModule]] ) -> None: self.handler = handler self.ui_modules = ui_modules def __getitem__(self, key: str) -> Callable[..., str]: return self.handler._ui_module(key, self.ui_modules[key]) def __getattr__(self, key: str) -> Callable[..., str]: try: return self[key] except KeyError as e: raise AttributeError(str(e)) def create_signed_value( secret: _CookieSecretTypes, name: str, value: Union[str, bytes], version: Optional[int] = None, clock: Optional[Callable[[], float]] = None, key_version: Optional[int] = None, ) -> bytes: if version is None: version = DEFAULT_SIGNED_VALUE_VERSION if clock is None: clock = time.time timestamp = utf8(str(int(clock()))) value = base64.b64encode(utf8(value)) if version == 1: assert not isinstance(secret, dict) signature = _create_signature_v1(secret, name, value, timestamp) value = b"|".join([value, timestamp, signature]) return value elif version == 2: # The v2 format consists of a version number and a series of # length-prefixed fields "%d:%s", the last of which is a # signature, all separated by pipes. All numbers are in # decimal format with no leading zeros. The signature is an # HMAC-SHA256 of the whole string up to that point, including # the final pipe. # # The fields are: # - format version (i.e. 2; no length prefix) # - key version (integer, default is 0) # - timestamp (integer seconds since epoch) # - name (not encoded; assumed to be ~alphanumeric) # - value (base64-encoded) # - signature (hex-encoded; no length prefix) def format_field(s: Union[str, bytes]) -> bytes: return utf8("%d:" % len(s)) + utf8(s) to_sign = b"|".join( [ b"2", format_field(str(key_version or 0)), format_field(timestamp), format_field(name), format_field(value), b"", ] ) if isinstance(secret, dict): assert ( key_version is not None ), "Key version must be set when sign key dict is used" assert version >= 2, "Version must be at least 2 for key version support" secret = secret[key_version] signature = _create_signature_v2(secret, to_sign) return to_sign + signature else: raise ValueError("Unsupported version %d" % version) # A leading version number in decimal # with no leading zeros, followed by a pipe. _signed_value_version_re = re.compile(rb"^([1-9][0-9]*)\|(.*)$") def _get_version(value: bytes) -> int: # Figures out what version value is. Version 1 did not include an # explicit version field and started with arbitrary base64 data, # which makes this tricky. m = _signed_value_version_re.match(value) if m is None: version = 1 else: try: version = int( if version > 999: # Certain payloads from the version-less v1 format may # be parsed as valid integers. Due to base64 padding # restrictions, this can only happen for numbers whose # length is a multiple of 4, so we can treat all # numbers up to 999 as versions, and for the rest we # fall back to v1 format. version = 1 except ValueError: version = 1 return version def decode_signed_value( secret: _CookieSecretTypes, name: str, value: Union[None, str, bytes], max_age_days: float = 31, clock: Optional[Callable[[], float]] = None, min_version: Optional[int] = None, ) -> Optional[bytes]: if clock is None: clock = time.time if min_version is None: min_version = DEFAULT_SIGNED_VALUE_MIN_VERSION if min_version > 2: raise ValueError("Unsupported min_version %d" % min_version) if not value: return None value = utf8(value) version = _get_version(value) if version < min_version: return None if version == 1: assert not isinstance(secret, dict) return _decode_signed_value_v1(secret, name, value, max_age_days, clock) elif version == 2: return _decode_signed_value_v2(secret, name, value, max_age_days, clock) else: return None def _decode_signed_value_v1( secret: Union[str, bytes], name: str, value: bytes, max_age_days: float, clock: Callable[[], float], ) -> Optional[bytes]: parts = utf8(value).split(b"|") if len(parts) != 3: return None signature = _create_signature_v1(secret, name, parts[0], parts[1]) if not hmac.compare_digest(parts[2], signature): gen_log.warning("Invalid cookie signature %r", value) return None timestamp = int(parts[1]) if timestamp < clock() - max_age_days * 86400: gen_log.warning("Expired cookie %r", value) return None if timestamp > clock() + 31 * 86400: # _cookie_signature does not hash a delimiter between the # parts of the cookie, so an attacker could transfer trailing # digits from the payload to the timestamp without altering the # signature. For backwards compatibility, sanity-check timestamp # here instead of modifying _cookie_signature. gen_log.warning("Cookie timestamp in future; possible tampering %r", value) return None if parts[1].startswith(b"0"): gen_log.warning("Tampered cookie %r", value) return None try: return base64.b64decode(parts[0]) except Exception: return None def _decode_fields_v2(value: bytes) -> Tuple[int, bytes, bytes, bytes, bytes]: def _consume_field(s: bytes) -> Tuple[bytes, bytes]: length, _, rest = s.partition(b":") n = int(length) field_value = rest[:n] # In python 3, indexing bytes returns small integers; we must # use a slice to get a byte string as in python 2. if rest[n : n + 1] != b"|": raise ValueError("malformed v2 signed value field") rest = rest[n + 1 :] return field_value, rest rest = value[2:] # remove version number key_version, rest = _consume_field(rest) timestamp, rest = _consume_field(rest) name_field, rest = _consume_field(rest) value_field, passed_sig = _consume_field(rest) return int(key_version), timestamp, name_field, value_field, passed_sig def _decode_signed_value_v2( secret: _CookieSecretTypes, name: str, value: bytes, max_age_days: float, clock: Callable[[], float], ) -> Optional[bytes]: try: ( key_version, timestamp_bytes, name_field, value_field, passed_sig, ) = _decode_fields_v2(value) except ValueError: return None signed_string = value[: -len(passed_sig)] if isinstance(secret, dict): try: secret = secret[key_version] except KeyError: return None expected_sig = _create_signature_v2(secret, signed_string) if not hmac.compare_digest(passed_sig, expected_sig): return None if name_field != utf8(name): return None timestamp = int(timestamp_bytes) if timestamp < clock() - max_age_days * 86400: # The signature has expired. return None try: return base64.b64decode(value_field) except Exception: return None def get_signature_key_version(value: Union[str, bytes]) -> Optional[int]: value = utf8(value) version = _get_version(value) if version < 2: return None try: key_version, _, _, _, _ = _decode_fields_v2(value) except ValueError: return None return key_version def _create_signature_v1(secret: Union[str, bytes], *parts: Union[str, bytes]) -> bytes: hash =, digestmod=hashlib.sha1) for part in parts: hash.update(utf8(part)) return utf8(hash.hexdigest()) def _create_signature_v2(secret: Union[str, bytes], s: bytes) -> bytes: hash =, digestmod=hashlib.sha256) hash.update(utf8(s)) return utf8(hash.hexdigest()) def is_absolute(path: str) -> bool: return any(path.startswith(x) for x in ["/", "http:", "https:"])