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1# Copyright 2015 The Tornado Authors
2#
3# Licensed under the Apache License, Version 2.0 (the "License"); you may
4# not use this file except in compliance with the License. You may obtain
5# a copy of the License at
6#
7# http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
11# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
12# License for the specific language governing permissions and limitations
13# under the License.
15"""Flexible routing implementation.
17Tornado routes HTTP requests to appropriate handlers using `Router`
18class implementations. The `tornado.web.Application` class is a
19`Router` implementation and may be used directly, or the classes in
20this module may be used for additional flexibility. The `RuleRouter`
21class can match on more criteria than `.Application`, or the `Router`
22interface can be subclassed for maximum customization.
24`Router` interface extends `~.httputil.HTTPServerConnectionDelegate`
25to provide additional routing capabilities. This also means that any
26`Router` implementation can be used directly as a ``request_callback``
27for `~.httpserver.HTTPServer` constructor.
29`Router` subclass must implement a ``find_handler`` method to provide
30a suitable `~.httputil.HTTPMessageDelegate` instance to handle the
31request:
33.. code-block:: python
35 class CustomRouter(Router):
36 def find_handler(self, request, **kwargs):
37 # some routing logic providing a suitable HTTPMessageDelegate instance
38 return MessageDelegate(request.connection)
40 class MessageDelegate(HTTPMessageDelegate):
41 def __init__(self, connection):
42 self.connection = connection
44 def finish(self):
45 self.connection.write_headers(
46 ResponseStartLine("HTTP/1.1", 200, "OK"),
47 HTTPHeaders({"Content-Length": "2"}),
48 b"OK")
49 self.connection.finish()
51 router = CustomRouter()
52 server = HTTPServer(router)
54The main responsibility of `Router` implementation is to provide a
55mapping from a request to `~.httputil.HTTPMessageDelegate` instance
56that will handle this request. In the example above we can see that
57routing is possible even without instantiating an `~.web.Application`.
59For routing to `~.web.RequestHandler` implementations we need an
60`~.web.Application` instance. `~.web.Application.get_handler_delegate`
61provides a convenient way to create `~.httputil.HTTPMessageDelegate`
62for a given request and `~.web.RequestHandler`.
64Here is a simple example of how we can we route to
65`~.web.RequestHandler` subclasses by HTTP method:
67.. code-block:: python
69 resources = {}
71 class GetResource(RequestHandler):
72 def get(self, path):
73 if path not in resources:
74 raise HTTPError(404)
76 self.finish(resources[path])
78 class PostResource(RequestHandler):
79 def post(self, path):
80 resources[path] = self.request.body
82 class HTTPMethodRouter(Router):
83 def __init__(self, app):
84 self.app = app
86 def find_handler(self, request, **kwargs):
87 handler = GetResource if request.method == "GET" else PostResource
88 return self.app.get_handler_delegate(request, handler, path_args=[request.path])
90 router = HTTPMethodRouter(Application())
91 server = HTTPServer(router)
93`ReversibleRouter` interface adds the ability to distinguish between
94the routes and reverse them to the original urls using route's name
95and additional arguments. `~.web.Application` is itself an
96implementation of `ReversibleRouter` class.
98`RuleRouter` and `ReversibleRuleRouter` are implementations of
99`Router` and `ReversibleRouter` interfaces and can be used for
100creating rule-based routing configurations.
102Rules are instances of `Rule` class. They contain a `Matcher`, which
103provides the logic for determining whether the rule is a match for a
104particular request and a target, which can be one of the following.
1061) An instance of `~.httputil.HTTPServerConnectionDelegate`:
108.. code-block:: python
110 router = RuleRouter([
111 Rule(PathMatches("/handler"), ConnectionDelegate()),
112 # ... more rules
113 ])
115 class ConnectionDelegate(HTTPServerConnectionDelegate):
116 def start_request(self, server_conn, request_conn):
117 return MessageDelegate(request_conn)
1192) A callable accepting a single argument of `~.httputil.HTTPServerRequest` type:
121.. code-block:: python
123 router = RuleRouter([
124 Rule(PathMatches("/callable"), request_callable)
125 ])
127 def request_callable(request):
128 request.write(b"HTTP/1.1 200 OK\\r\\nContent-Length: 2\\r\\n\\r\\nOK")
129 request.finish()
1313) Another `Router` instance:
133.. code-block:: python
135 router = RuleRouter([
136 Rule(PathMatches("/router.*"), CustomRouter())
137 ])
139Of course a nested `RuleRouter` or a `~.web.Application` is allowed:
141.. code-block:: python
143 router = RuleRouter([
144 Rule(HostMatches("example.com"), RuleRouter([
145 Rule(PathMatches("/app1/.*"), Application([(r"/app1/handler", Handler)])),
146 ]))
147 ])
149 server = HTTPServer(router)
151In the example below `RuleRouter` is used to route between applications:
153.. code-block:: python
155 app1 = Application([
156 (r"/app1/handler", Handler1),
157 # other handlers ...
158 ])
160 app2 = Application([
161 (r"/app2/handler", Handler2),
162 # other handlers ...
163 ])
165 router = RuleRouter([
166 Rule(PathMatches("/app1.*"), app1),
167 Rule(PathMatches("/app2.*"), app2)
168 ])
170 server = HTTPServer(router)
172For more information on application-level routing see docs for `~.web.Application`.
174.. versionadded:: 4.5
176"""
178import re
179from collections.abc import Awaitable, Sequence
180from functools import partial
181from re import Pattern
182from typing import (
183 Any,
184 Union,
185 overload,
186)
188from tornado import httputil
189from tornado.escape import url_escape, url_unescape, utf8
190from tornado.httpserver import _CallableAdapter
191from tornado.log import app_log
192from tornado.util import basestring_type, import_object, re_unescape, unicode_type
195class Router(httputil.HTTPServerConnectionDelegate):
196 """Abstract router interface."""
198 def find_handler(
199 self, request: httputil.HTTPServerRequest, **kwargs: Any
200 ) -> httputil.HTTPMessageDelegate | None:
201 """Must be implemented to return an appropriate instance of `~.httputil.HTTPMessageDelegate`
202 that can serve the request.
203 Routing implementations may pass additional kwargs to extend the routing logic.
205 :arg httputil.HTTPServerRequest request: current HTTP request.
206 :arg kwargs: additional keyword arguments passed by routing implementation.
207 :returns: an instance of `~.httputil.HTTPMessageDelegate` that will be used to
208 process the request.
209 """
210 raise NotImplementedError()
212 def start_request(
213 self, server_conn: object, request_conn: httputil.HTTPConnection
214 ) -> httputil.HTTPMessageDelegate:
215 return _RoutingDelegate(self, server_conn, request_conn)
218class ReversibleRouter(Router):
219 """Abstract router interface for routers that can handle named routes
220 and support reversing them to original urls.
221 """
223 def reverse_url(self, name: str, *args: Any) -> str | None:
224 """Returns url string for a given route name and arguments
225 or ``None`` if no match is found.
227 :arg str name: route name.
228 :arg args: url parameters.
229 :returns: parametrized url string for a given route name (or ``None``).
230 """
231 raise NotImplementedError()
234class _RoutingDelegate(httputil.HTTPMessageDelegate):
235 def __init__(
236 self, router: Router, server_conn: object, request_conn: httputil.HTTPConnection
237 ) -> None:
238 self.server_conn = server_conn
239 self.request_conn = request_conn
240 self.delegate: httputil.HTTPMessageDelegate | None = None
241 self.router: Router = router
243 def headers_received(
244 self,
245 start_line: httputil.RequestStartLine | httputil.ResponseStartLine,
246 headers: httputil.HTTPHeaders,
247 ) -> Awaitable[None] | None:
248 assert isinstance(start_line, httputil.RequestStartLine)
249 request = httputil.HTTPServerRequest(
250 connection=self.request_conn,
251 server_connection=self.server_conn,
252 start_line=start_line,
253 headers=headers,
254 )
256 self.delegate = self.router.find_handler(request)
257 if self.delegate is None:
258 app_log.debug(
259 "Delegate for %s %s request not found",
260 start_line.method,
261 start_line.path,
262 )
263 self.delegate = _DefaultMessageDelegate(self.request_conn)
265 return self.delegate.headers_received(start_line, headers)
267 def data_received(self, chunk: bytes) -> Awaitable[None] | None:
268 assert self.delegate is not None
269 return self.delegate.data_received(chunk)
271 def finish(self) -> None:
272 assert self.delegate is not None
273 self.delegate.finish()
275 def on_connection_close(self) -> None:
276 if self.delegate is not None:
277 self.delegate.on_connection_close()
280class _DefaultMessageDelegate(httputil.HTTPMessageDelegate):
281 def __init__(self, connection: httputil.HTTPConnection) -> None:
282 self.connection = connection
284 def finish(self) -> None:
285 self.connection.write_headers(
286 httputil.ResponseStartLine("HTTP/1.1", 404, "Not Found"),
287 httputil.HTTPHeaders(),
288 )
289 self.connection.finish()
292# _RuleList can either contain pre-constructed Rules or a sequence of
293# arguments to be passed to the Rule constructor.
294_RuleList = Sequence[
295 Union[
296 "Rule",
297 list[Any], # Can't do detailed typechecking of lists.
298 tuple[Union[str, "Matcher"], Any],
299 tuple[Union[str, "Matcher"], Any, dict[str, Any]],
300 tuple[Union[str, "Matcher"], Any, dict[str, Any], str],
301 ]
302]
305class RuleRouter(Router):
306 """Rule-based router implementation."""
308 def __init__(self, rules: _RuleList | None = None) -> None:
309 """Constructs a router from an ordered list of rules::
311 RuleRouter([
312 Rule(PathMatches("/handler"), Target),
313 # ... more rules
314 ])
316 You can also omit explicit `Rule` constructor and use tuples of arguments::
318 RuleRouter([
319 (PathMatches("/handler"), Target),
320 ])
322 `PathMatches` is a default matcher, so the example above can be simplified::
324 RuleRouter([
325 ("/handler", Target),
326 ])
328 In the examples above, ``Target`` can be a nested `Router` instance, an instance of
329 `~.httputil.HTTPServerConnectionDelegate` or an old-style callable,
330 accepting a request argument.
332 :arg rules: a list of `Rule` instances or tuples of `Rule`
333 constructor arguments.
334 """
335 self.rules: list[Rule] = []
336 if rules:
337 self.add_rules(rules)
339 def add_rules(self, rules: _RuleList) -> None:
340 """Appends new rules to the router.
342 :arg rules: a list of Rule instances (or tuples of arguments, which are
343 passed to Rule constructor).
344 """
345 for rule in rules:
346 if isinstance(rule, (tuple, list)):
347 assert len(rule) in (2, 3, 4)
348 if isinstance(rule[0], basestring_type):
349 rule = Rule(PathMatches(rule[0]), *rule[1:])
350 else:
351 rule = Rule(*rule)
353 self.rules.append(self.process_rule(rule))
355 def process_rule(self, rule: "Rule") -> "Rule":
356 """Override this method for additional preprocessing of each rule.
358 :arg Rule rule: a rule to be processed.
359 :returns: the same or modified Rule instance.
360 """
361 return rule
363 def find_handler(
364 self, request: httputil.HTTPServerRequest, **kwargs: Any
365 ) -> httputil.HTTPMessageDelegate | None:
366 for rule in self.rules:
367 target_params = rule.matcher.match(request)
368 if target_params is not None:
369 if rule.target_kwargs:
370 target_params["target_kwargs"] = rule.target_kwargs
372 delegate = self.get_target_delegate(
373 rule.target, request, **target_params
374 )
376 if delegate is not None:
377 return delegate
379 return None
381 def get_target_delegate(
382 self, target: Any, request: httputil.HTTPServerRequest, **target_params: Any
383 ) -> httputil.HTTPMessageDelegate | None:
384 """Returns an instance of `~.httputil.HTTPMessageDelegate` for a
385 Rule's target. This method is called by `~.find_handler` and can be
386 extended to provide additional target types.
388 :arg target: a Rule's target.
389 :arg httputil.HTTPServerRequest request: current request.
390 :arg target_params: additional parameters that can be useful
391 for `~.httputil.HTTPMessageDelegate` creation.
392 """
393 if isinstance(target, Router):
394 return target.find_handler(request, **target_params)
396 elif isinstance(target, httputil.HTTPServerConnectionDelegate):
397 assert request.connection is not None
398 return target.start_request(request.server_connection, request.connection)
400 elif callable(target):
401 assert request.connection is not None
402 return _CallableAdapter(
403 partial(target, **target_params), request.connection
404 )
406 return None
409class ReversibleRuleRouter(ReversibleRouter, RuleRouter):
410 """A rule-based router that implements ``reverse_url`` method.
412 Each rule added to this router may have a ``name`` attribute that can be
413 used to reconstruct an original uri. The actual reconstruction takes place
414 in a rule's matcher (see `Matcher.reverse`).
415 """
417 def __init__(self, rules: _RuleList | None = None) -> None:
418 self.named_rules: dict[str, Any] = {}
419 super().__init__(rules)
421 def process_rule(self, rule: "Rule") -> "Rule":
422 rule = super().process_rule(rule)
424 if rule.name:
425 if rule.name in self.named_rules:
426 app_log.warning(
427 "Multiple handlers named %s; replacing previous value", rule.name
428 )
429 self.named_rules[rule.name] = rule
431 return rule
433 def reverse_url(self, name: str, *args: Any) -> str | None:
434 if name in self.named_rules:
435 return self.named_rules[name].matcher.reverse(*args)
437 for rule in self.rules:
438 if isinstance(rule.target, ReversibleRouter):
439 reversed_url = rule.target.reverse_url(name, *args)
440 if reversed_url is not None:
441 return reversed_url
443 return None
446class Rule:
447 """A routing rule."""
449 def __init__(
450 self,
451 matcher: "Matcher",
452 target: Any,
453 target_kwargs: dict[str, Any] | None = None,
454 name: str | None = None,
455 ) -> None:
456 """Constructs a Rule instance.
458 :arg Matcher matcher: a `Matcher` instance used for determining
459 whether the rule should be considered a match for a specific
460 request.
461 :arg target: a Rule's target (typically a ``RequestHandler`` or
462 `~.httputil.HTTPServerConnectionDelegate` subclass or even a nested `Router`,
463 depending on routing implementation).
464 :arg dict target_kwargs: a dict of parameters that can be useful
465 at the moment of target instantiation (for example, ``status_code``
466 for a ``RequestHandler`` subclass). They end up in
467 ``target_params['target_kwargs']`` of `RuleRouter.get_target_delegate`
468 method.
469 :arg str name: the name of the rule that can be used to find it
470 in `ReversibleRouter.reverse_url` implementation.
471 """
472 if isinstance(target, str):
473 # import the Module and instantiate the class
474 # Must be a fully qualified name (module.ClassName)
475 target = import_object(target)
477 self.matcher: Matcher = matcher
478 self.target = target
479 self.target_kwargs = target_kwargs if target_kwargs else {}
480 self.name = name
482 def reverse(self, *args: Any) -> str | None:
483 return self.matcher.reverse(*args)
485 def __repr__(self) -> str:
486 return "{}({!r}, {}, kwargs={!r}, name={!r})".format(
487 self.__class__.__name__,
488 self.matcher,
489 self.target,
490 self.target_kwargs,
491 self.name,
492 )
495class Matcher:
496 """Represents a matcher for request features."""
498 def match(self, request: httputil.HTTPServerRequest) -> dict[str, Any] | None:
499 """Matches current instance against the request.
501 :arg httputil.HTTPServerRequest request: current HTTP request
502 :returns: a dict of parameters to be passed to the target handler
503 (for example, ``handler_kwargs``, ``path_args``, ``path_kwargs``
504 can be passed for proper `~.web.RequestHandler` instantiation).
505 An empty dict is a valid (and common) return value to indicate a match
506 when the argument-passing features are not used.
507 ``None`` must be returned to indicate that there is no match."""
508 raise NotImplementedError()
510 def reverse(self, *args: Any) -> str | None:
511 """Reconstructs full url from matcher instance and additional arguments."""
512 return None
515class AnyMatches(Matcher):
516 """Matches any request."""
518 def match(self, request: httputil.HTTPServerRequest) -> dict[str, Any] | None:
519 return {}
522class HostMatches(Matcher):
523 """Matches requests from hosts specified by ``host_pattern`` regex."""
525 def __init__(self, host_pattern: str | Pattern) -> None:
526 if isinstance(host_pattern, basestring_type):
527 if not host_pattern.endswith("$"):
528 host_pattern += "$"
529 self.host_pattern = re.compile(host_pattern)
530 else:
531 self.host_pattern = host_pattern
533 def match(self, request: httputil.HTTPServerRequest) -> dict[str, Any] | None:
534 if self.host_pattern.match(request.host_name):
535 return {}
537 return None
540class DefaultHostMatches(Matcher):
541 """Matches requests from host that is equal to application's default_host.
542 Always returns no match if ``X-Real-Ip`` header is present.
543 """
545 def __init__(self, application: Any, host_pattern: Pattern) -> None:
546 self.application = application
547 self.host_pattern = host_pattern
549 def match(self, request: httputil.HTTPServerRequest) -> dict[str, Any] | None:
550 # Look for default host if not behind load balancer (for debugging)
551 if "X-Real-Ip" not in request.headers:
552 if self.host_pattern.match(self.application.default_host):
553 return {}
554 return None
557class PathMatches(Matcher):
558 """Matches requests with paths specified by ``path_pattern`` regex."""
560 def __init__(self, path_pattern: str | Pattern) -> None:
561 if isinstance(path_pattern, basestring_type):
562 if not path_pattern.endswith("$"):
563 path_pattern += "$"
564 self.regex = re.compile(path_pattern)
565 else:
566 self.regex = path_pattern
568 assert len(self.regex.groupindex) in (0, self.regex.groups), (
569 "groups in url regexes must either be all named or all "
570 "positional: %r" % self.regex.pattern
571 )
573 self._path, self._group_count = self._find_groups()
575 def match(self, request: httputil.HTTPServerRequest) -> dict[str, Any] | None:
576 match = self.regex.match(request.path)
577 if match is None:
578 return None
579 if not self.regex.groups:
580 return {}
582 path_args: list[bytes] = []
583 path_kwargs: dict[str, bytes] = {}
585 # Pass matched groups to the handler. Since
586 # match.groups() includes both named and
587 # unnamed groups, we want to use either groups
588 # or groupdict but not both.
589 if self.regex.groupindex:
590 path_kwargs = {
591 str(k): _unquote_or_none(v) for (k, v) in match.groupdict().items()
592 }
593 else:
594 path_args = [_unquote_or_none(s) for s in match.groups()]
596 return dict(path_args=path_args, path_kwargs=path_kwargs)
598 def reverse(self, *args: Any) -> str | None:
599 if self._path is None:
600 raise ValueError("Cannot reverse url regex " + self.regex.pattern)
601 assert len(args) == self._group_count, (
602 "required number of arguments " "not found"
603 )
604 if not len(args):
605 return self._path
606 converted_args = []
607 for a in args:
608 if not isinstance(a, (unicode_type, bytes)):
609 a = str(a)
610 converted_args.append(url_escape(utf8(a), plus=False))
611 return self._path % tuple(converted_args)
613 def _find_groups(self) -> tuple[str | None, int | None]:
614 """Returns a tuple (reverse string, group count) for a url.
616 For example: Given the url pattern /([0-9]{4})/([a-z-]+)/, this method
617 would return ('/%s/%s/', 2).
618 """
619 pattern = self.regex.pattern
620 if pattern.startswith("^"):
621 pattern = pattern[1:]
622 if pattern.endswith("$"):
623 pattern = pattern[:-1]
625 if self.regex.groups != pattern.count("("):
626 # The pattern is too complicated for our simplistic matching,
627 # so we can't support reversing it.
628 return None, None
630 pieces = []
631 for fragment in pattern.split("("):
632 if ")" in fragment:
633 paren_loc = fragment.index(")")
634 if paren_loc >= 0:
635 try:
636 unescaped_fragment = re_unescape(fragment[paren_loc + 1 :])
637 except ValueError:
638 # If we can't unescape part of it, we can't
639 # reverse this url.
640 return (None, None)
641 pieces.append("%s" + unescaped_fragment)
642 else:
643 try:
644 unescaped_fragment = re_unescape(fragment)
645 except ValueError:
646 # If we can't unescape part of it, we can't
647 # reverse this url.
648 return (None, None)
649 pieces.append(unescaped_fragment)
651 return "".join(pieces), self.regex.groups
654class URLSpec(Rule):
655 """Specifies mappings between URLs and handlers.
657 .. versionchanged: 4.5
658 `URLSpec` is now a subclass of a `Rule` with `PathMatches` matcher and is preserved for
659 backwards compatibility.
660 """
662 def __init__(
663 self,
664 pattern: str | Pattern,
665 handler: Any,
666 kwargs: dict[str, Any] | None = None,
667 name: str | None = None,
668 ) -> None:
669 """Parameters:
671 * ``pattern``: Regular expression to be matched. Any capturing
672 groups in the regex will be passed in to the handler's
673 get/post/etc methods as arguments (by keyword if named, by
674 position if unnamed. Named and unnamed capturing groups
675 may not be mixed in the same rule).
677 * ``handler``: `~.web.RequestHandler` subclass to be invoked.
679 * ``kwargs`` (optional): A dictionary of additional arguments
680 to be passed to the handler's constructor.
682 * ``name`` (optional): A name for this handler. Used by
683 `~.web.Application.reverse_url`.
685 """
686 matcher = PathMatches(pattern)
687 super().__init__(matcher, handler, kwargs, name)
689 self.regex = matcher.regex
690 self.handler_class = self.target
691 self.kwargs = kwargs
693 def __repr__(self) -> str:
694 return "{}({!r}, {}, kwargs={!r}, name={!r})".format(
695 self.__class__.__name__,
696 self.regex.pattern,
697 self.handler_class,
698 self.kwargs,
699 self.name,
700 )
703@overload
704def _unquote_or_none(s: str) -> bytes:
705 pass
708@overload
709def _unquote_or_none(s: None) -> None:
710 pass
713def _unquote_or_none(s: str | None) -> bytes | None:
714 """None-safe wrapper around url_unescape to handle unmatched optional
715 groups correctly.
717 Note that args are passed as bytes so the handler can decide what
718 encoding to use.
719 """
720 if s is None:
721 return s
722 return url_unescape(s, encoding=None, plus=False)