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Diffstat (limited to 'cherrypy/_cpdispatch.py')
| -rwxr-xr-x | cherrypy/_cpdispatch.py | 622 |
1 files changed, 622 insertions, 0 deletions
diff --git a/cherrypy/_cpdispatch.py b/cherrypy/_cpdispatch.py new file mode 100755 index 0000000..7250ac9 --- /dev/null +++ b/cherrypy/_cpdispatch.py @@ -0,0 +1,622 @@ +"""CherryPy dispatchers. + +A 'dispatcher' is the object which looks up the 'page handler' callable +and collects config for the current request based on the path_info, other +request attributes, and the application architecture. The core calls the +dispatcher as early as possible, passing it a 'path_info' argument. + +The default dispatcher discovers the page handler by matching path_info +to a hierarchical arrangement of objects, starting at request.app.root. +""" + +import string +import sys +import types + +import cherrypy + + +class PageHandler(object): + """Callable which sets response.body.""" + + def __init__(self, callable, *args, **kwargs): + self.callable = callable + self.args = args + self.kwargs = kwargs + + def __call__(self): + try: + return self.callable(*self.args, **self.kwargs) + except TypeError: + x = sys.exc_info()[1] + try: + test_callable_spec(self.callable, self.args, self.kwargs) + except cherrypy.HTTPError: + raise sys.exc_info()[1] + except: + raise x + raise + + +def test_callable_spec(callable, callable_args, callable_kwargs): + """ + Inspect callable and test to see if the given args are suitable for it. + + When an error occurs during the handler's invoking stage there are 2 + erroneous cases: + 1. Too many parameters passed to a function which doesn't define + one of *args or **kwargs. + 2. Too little parameters are passed to the function. + + There are 3 sources of parameters to a cherrypy handler. + 1. query string parameters are passed as keyword parameters to the handler. + 2. body parameters are also passed as keyword parameters. + 3. when partial matching occurs, the final path atoms are passed as + positional args. + Both the query string and path atoms are part of the URI. If they are + incorrect, then a 404 Not Found should be raised. Conversely the body + parameters are part of the request; if they are invalid a 400 Bad Request. + """ + show_mismatched_params = getattr( + cherrypy.serving.request, 'show_mismatched_params', False) + try: + (args, varargs, varkw, defaults) = inspect.getargspec(callable) + except TypeError: + if isinstance(callable, object) and hasattr(callable, '__call__'): + (args, varargs, varkw, defaults) = inspect.getargspec(callable.__call__) + else: + # If it wasn't one of our own types, re-raise + # the original error + raise + + if args and args[0] == 'self': + args = args[1:] + + arg_usage = dict([(arg, 0,) for arg in args]) + vararg_usage = 0 + varkw_usage = 0 + extra_kwargs = set() + + for i, value in enumerate(callable_args): + try: + arg_usage[args[i]] += 1 + except IndexError: + vararg_usage += 1 + + for key in callable_kwargs.keys(): + try: + arg_usage[key] += 1 + except KeyError: + varkw_usage += 1 + extra_kwargs.add(key) + + # figure out which args have defaults. + args_with_defaults = args[-len(defaults or []):] + for i, val in enumerate(defaults or []): + # Defaults take effect only when the arg hasn't been used yet. + if arg_usage[args_with_defaults[i]] == 0: + arg_usage[args_with_defaults[i]] += 1 + + missing_args = [] + multiple_args = [] + for key, usage in arg_usage.items(): + if usage == 0: + missing_args.append(key) + elif usage > 1: + multiple_args.append(key) + + if missing_args: + # In the case where the method allows body arguments + # there are 3 potential errors: + # 1. not enough query string parameters -> 404 + # 2. not enough body parameters -> 400 + # 3. not enough path parts (partial matches) -> 404 + # + # We can't actually tell which case it is, + # so I'm raising a 404 because that covers 2/3 of the + # possibilities + # + # In the case where the method does not allow body + # arguments it's definitely a 404. + message = None + if show_mismatched_params: + message="Missing parameters: %s" % ",".join(missing_args) + raise cherrypy.HTTPError(404, message=message) + + # the extra positional arguments come from the path - 404 Not Found + if not varargs and vararg_usage > 0: + raise cherrypy.HTTPError(404) + + body_params = cherrypy.serving.request.body.params or {} + body_params = set(body_params.keys()) + qs_params = set(callable_kwargs.keys()) - body_params + + if multiple_args: + if qs_params.intersection(set(multiple_args)): + # If any of the multiple parameters came from the query string then + # it's a 404 Not Found + error = 404 + else: + # Otherwise it's a 400 Bad Request + error = 400 + + message = None + if show_mismatched_params: + message="Multiple values for parameters: "\ + "%s" % ",".join(multiple_args) + raise cherrypy.HTTPError(error, message=message) + + if not varkw and varkw_usage > 0: + + # If there were extra query string parameters, it's a 404 Not Found + extra_qs_params = set(qs_params).intersection(extra_kwargs) + if extra_qs_params: + message = None + if show_mismatched_params: + message="Unexpected query string "\ + "parameters: %s" % ", ".join(extra_qs_params) + raise cherrypy.HTTPError(404, message=message) + + # If there were any extra body parameters, it's a 400 Not Found + extra_body_params = set(body_params).intersection(extra_kwargs) + if extra_body_params: + message = None + if show_mismatched_params: + message="Unexpected body parameters: "\ + "%s" % ", ".join(extra_body_params) + raise cherrypy.HTTPError(400, message=message) + + +try: + import inspect +except ImportError: + test_callable_spec = lambda callable, args, kwargs: None + + + +class LateParamPageHandler(PageHandler): + """When passing cherrypy.request.params to the page handler, we do not + want to capture that dict too early; we want to give tools like the + decoding tool a chance to modify the params dict in-between the lookup + of the handler and the actual calling of the handler. This subclass + takes that into account, and allows request.params to be 'bound late' + (it's more complicated than that, but that's the effect). + """ + + def _get_kwargs(self): + kwargs = cherrypy.serving.request.params.copy() + if self._kwargs: + kwargs.update(self._kwargs) + return kwargs + + def _set_kwargs(self, kwargs): + self._kwargs = kwargs + + kwargs = property(_get_kwargs, _set_kwargs, + doc='page handler kwargs (with ' + 'cherrypy.request.params copied in)') + + +punctuation_to_underscores = string.maketrans( + string.punctuation, '_' * len(string.punctuation)) + +class Dispatcher(object): + """CherryPy Dispatcher which walks a tree of objects to find a handler. + + The tree is rooted at cherrypy.request.app.root, and each hierarchical + component in the path_info argument is matched to a corresponding nested + attribute of the root object. Matching handlers must have an 'exposed' + attribute which evaluates to True. The special method name "index" + matches a URI which ends in a slash ("/"). The special method name + "default" may match a portion of the path_info (but only when no longer + substring of the path_info matches some other object). + + This is the default, built-in dispatcher for CherryPy. + """ + + dispatch_method_name = '_cp_dispatch' + """ + The name of the dispatch method that nodes may optionally implement + to provide their own dynamic dispatch algorithm. + """ + + def __init__(self, dispatch_method_name=None, + translate=punctuation_to_underscores): + if not isinstance(translate, str) or len(translate) != 256: + raise ValueError("The translate argument must be a str of len 256.") + self.translate = translate + if dispatch_method_name: + self.dispatch_method_name = dispatch_method_name + + def __call__(self, path_info): + """Set handler and config for the current request.""" + request = cherrypy.serving.request + func, vpath = self.find_handler(path_info) + + if func: + # Decode any leftover %2F in the virtual_path atoms. + vpath = [x.replace("%2F", "/") for x in vpath] + request.handler = LateParamPageHandler(func, *vpath) + else: + request.handler = cherrypy.NotFound() + + def find_handler(self, path): + """Return the appropriate page handler, plus any virtual path. + + This will return two objects. The first will be a callable, + which can be used to generate page output. Any parameters from + the query string or request body will be sent to that callable + as keyword arguments. + + The callable is found by traversing the application's tree, + starting from cherrypy.request.app.root, and matching path + components to successive objects in the tree. For example, the + URL "/path/to/handler" might return root.path.to.handler. + + The second object returned will be a list of names which are + 'virtual path' components: parts of the URL which are dynamic, + and were not used when looking up the handler. + These virtual path components are passed to the handler as + positional arguments. + """ + request = cherrypy.serving.request + app = request.app + root = app.root + dispatch_name = self.dispatch_method_name + + # Get config for the root object/path. + fullpath = [x for x in path.strip('/').split('/') if x] + ['index'] + fullpath_len = len(fullpath) + segleft = fullpath_len + nodeconf = {} + if hasattr(root, "_cp_config"): + nodeconf.update(root._cp_config) + if "/" in app.config: + nodeconf.update(app.config["/"]) + object_trail = [['root', root, nodeconf, segleft]] + + node = root + iternames = fullpath[:] + while iternames: + name = iternames[0] + # map to legal Python identifiers (e.g. replace '.' with '_') + objname = name.translate(self.translate) + + nodeconf = {} + subnode = getattr(node, objname, None) + pre_len = len(iternames) + if subnode is None: + dispatch = getattr(node, dispatch_name, None) + if dispatch and hasattr(dispatch, '__call__') and not \ + getattr(dispatch, 'exposed', False) and \ + pre_len > 1: + #Don't expose the hidden 'index' token to _cp_dispatch + #We skip this if pre_len == 1 since it makes no sense + #to call a dispatcher when we have no tokens left. + index_name = iternames.pop() + subnode = dispatch(vpath=iternames) + iternames.append(index_name) + else: + #We didn't find a path, but keep processing in case there + #is a default() handler. + iternames.pop(0) + else: + #We found the path, remove the vpath entry + iternames.pop(0) + segleft = len(iternames) + if segleft > pre_len: + #No path segment was removed. Raise an error. + raise cherrypy.CherryPyException( + "A vpath segment was added. Custom dispatchers may only " + + "remove elements. While trying to process " + + "{0} in {1}".format(name, fullpath) + ) + elif segleft == pre_len: + #Assume that the handler used the current path segment, but + #did not pop it. This allows things like + #return getattr(self, vpath[0], None) + iternames.pop(0) + segleft -= 1 + node = subnode + + if node is not None: + # Get _cp_config attached to this node. + if hasattr(node, "_cp_config"): + nodeconf.update(node._cp_config) + + # Mix in values from app.config for this path. + existing_len = fullpath_len - pre_len + if existing_len != 0: + curpath = '/' + '/'.join(fullpath[0:existing_len]) + else: + curpath = '' + new_segs = fullpath[fullpath_len - pre_len:fullpath_len - segleft] + for seg in new_segs: + curpath += '/' + seg + if curpath in app.config: + nodeconf.update(app.config[curpath]) + + object_trail.append([name, node, nodeconf, segleft]) + + def set_conf(): + """Collapse all object_trail config into cherrypy.request.config.""" + base = cherrypy.config.copy() + # Note that we merge the config from each node + # even if that node was None. + for name, obj, conf, segleft in object_trail: + base.update(conf) + if 'tools.staticdir.dir' in conf: + base['tools.staticdir.section'] = '/' + '/'.join(fullpath[0:fullpath_len - segleft]) + return base + + # Try successive objects (reverse order) + num_candidates = len(object_trail) - 1 + for i in range(num_candidates, -1, -1): + + name, candidate, nodeconf, segleft = object_trail[i] + if candidate is None: + continue + + # Try a "default" method on the current leaf. + if hasattr(candidate, "default"): + defhandler = candidate.default + if getattr(defhandler, 'exposed', False): + # Insert any extra _cp_config from the default handler. + conf = getattr(defhandler, "_cp_config", {}) + object_trail.insert(i+1, ["default", defhandler, conf, segleft]) + request.config = set_conf() + # See http://www.cherrypy.org/ticket/613 + request.is_index = path.endswith("/") + return defhandler, fullpath[fullpath_len - segleft:-1] + + # Uncomment the next line to restrict positional params to "default". + # if i < num_candidates - 2: continue + + # Try the current leaf. + if getattr(candidate, 'exposed', False): + request.config = set_conf() + if i == num_candidates: + # We found the extra ".index". Mark request so tools + # can redirect if path_info has no trailing slash. + request.is_index = True + else: + # We're not at an 'index' handler. Mark request so tools + # can redirect if path_info has NO trailing slash. + # Note that this also includes handlers which take + # positional parameters (virtual paths). + request.is_index = False + return candidate, fullpath[fullpath_len - segleft:-1] + + # We didn't find anything + request.config = set_conf() + return None, [] + + +class MethodDispatcher(Dispatcher): + """Additional dispatch based on cherrypy.request.method.upper(). + + Methods named GET, POST, etc will be called on an exposed class. + The method names must be all caps; the appropriate Allow header + will be output showing all capitalized method names as allowable + HTTP verbs. + + Note that the containing class must be exposed, not the methods. + """ + + def __call__(self, path_info): + """Set handler and config for the current request.""" + request = cherrypy.serving.request + resource, vpath = self.find_handler(path_info) + + if resource: + # Set Allow header + avail = [m for m in dir(resource) if m.isupper()] + if "GET" in avail and "HEAD" not in avail: + avail.append("HEAD") + avail.sort() + cherrypy.serving.response.headers['Allow'] = ", ".join(avail) + + # Find the subhandler + meth = request.method.upper() + func = getattr(resource, meth, None) + if func is None and meth == "HEAD": + func = getattr(resource, "GET", None) + if func: + # Grab any _cp_config on the subhandler. + if hasattr(func, "_cp_config"): + request.config.update(func._cp_config) + + # Decode any leftover %2F in the virtual_path atoms. + vpath = [x.replace("%2F", "/") for x in vpath] + request.handler = LateParamPageHandler(func, *vpath) + else: + request.handler = cherrypy.HTTPError(405) + else: + request.handler = cherrypy.NotFound() + + +class RoutesDispatcher(object): + """A Routes based dispatcher for CherryPy.""" + + def __init__(self, full_result=False): + """ + Routes dispatcher + + Set full_result to True if you wish the controller + and the action to be passed on to the page handler + parameters. By default they won't be. + """ + import routes + self.full_result = full_result + self.controllers = {} + self.mapper = routes.Mapper() + self.mapper.controller_scan = self.controllers.keys + + def connect(self, name, route, controller, **kwargs): + self.controllers[name] = controller + self.mapper.connect(name, route, controller=name, **kwargs) + + def redirect(self, url): + raise cherrypy.HTTPRedirect(url) + + def __call__(self, path_info): + """Set handler and config for the current request.""" + func = self.find_handler(path_info) + if func: + cherrypy.serving.request.handler = LateParamPageHandler(func) + else: + cherrypy.serving.request.handler = cherrypy.NotFound() + + def find_handler(self, path_info): + """Find the right page handler, and set request.config.""" + import routes + + request = cherrypy.serving.request + + config = routes.request_config() + config.mapper = self.mapper + if hasattr(request, 'wsgi_environ'): + config.environ = request.wsgi_environ + config.host = request.headers.get('Host', None) + config.protocol = request.scheme + config.redirect = self.redirect + + result = self.mapper.match(path_info) + + config.mapper_dict = result + params = {} + if result: + params = result.copy() + if not self.full_result: + params.pop('controller', None) + params.pop('action', None) + request.params.update(params) + + # Get config for the root object/path. + request.config = base = cherrypy.config.copy() + curpath = "" + + def merge(nodeconf): + if 'tools.staticdir.dir' in nodeconf: + nodeconf['tools.staticdir.section'] = curpath or "/" + base.update(nodeconf) + + app = request.app + root = app.root + if hasattr(root, "_cp_config"): + merge(root._cp_config) + if "/" in app.config: + merge(app.config["/"]) + + # Mix in values from app.config. + atoms = [x for x in path_info.split("/") if x] + if atoms: + last = atoms.pop() + else: + last = None + for atom in atoms: + curpath = "/".join((curpath, atom)) + if curpath in app.config: + merge(app.config[curpath]) + + handler = None + if result: + controller = result.get('controller') + controller = self.controllers.get(controller, controller) + if controller: + if isinstance(controller, (type, types.ClassType)): + controller = controller() + # Get config from the controller. + if hasattr(controller, "_cp_config"): + merge(controller._cp_config) + + action = result.get('action') + if action is not None: + handler = getattr(controller, action, None) + # Get config from the handler + if hasattr(handler, "_cp_config"): + merge(handler._cp_config) + else: + handler = controller + + # Do the last path atom here so it can + # override the controller's _cp_config. + if last: + curpath = "/".join((curpath, last)) + if curpath in app.config: + merge(app.config[curpath]) + + return handler + + +def XMLRPCDispatcher(next_dispatcher=Dispatcher()): + from cherrypy.lib import xmlrpc + def xmlrpc_dispatch(path_info): + path_info = xmlrpc.patched_path(path_info) + return next_dispatcher(path_info) + return xmlrpc_dispatch + + +def VirtualHost(next_dispatcher=Dispatcher(), use_x_forwarded_host=True, **domains): + """ + Select a different handler based on the Host header. + + This can be useful when running multiple sites within one CP server. + It allows several domains to point to different parts of a single + website structure. For example:: + + http://www.domain.example -> root + http://www.domain2.example -> root/domain2/ + http://www.domain2.example:443 -> root/secure + + can be accomplished via the following config:: + + [/] + request.dispatch = cherrypy.dispatch.VirtualHost( + **{'www.domain2.example': '/domain2', + 'www.domain2.example:443': '/secure', + }) + + next_dispatcher + The next dispatcher object in the dispatch chain. + The VirtualHost dispatcher adds a prefix to the URL and calls + another dispatcher. Defaults to cherrypy.dispatch.Dispatcher(). + + use_x_forwarded_host + If True (the default), any "X-Forwarded-Host" + request header will be used instead of the "Host" header. This + is commonly added by HTTP servers (such as Apache) when proxying. + + ``**domains`` + A dict of {host header value: virtual prefix} pairs. + The incoming "Host" request header is looked up in this dict, + and, if a match is found, the corresponding "virtual prefix" + value will be prepended to the URL path before calling the + next dispatcher. Note that you often need separate entries + for "example.com" and "www.example.com". In addition, "Host" + headers may contain the port number. + """ + from cherrypy.lib import httputil + def vhost_dispatch(path_info): + request = cherrypy.serving.request + header = request.headers.get + + domain = header('Host', '') + if use_x_forwarded_host: + domain = header("X-Forwarded-Host", domain) + + prefix = domains.get(domain, "") + if prefix: + path_info = httputil.urljoin(prefix, path_info) + + result = next_dispatcher(path_info) + + # Touch up staticdir config. See http://www.cherrypy.org/ticket/614. + section = request.config.get('tools.staticdir.section') + if section: + section = section[len(prefix):] + request.config['tools.staticdir.section'] = section + + return result + return vhost_dispatch + |