Source code for cherrypy.lib.cptools

"""Functions for builtin CherryPy tools."""

import logging
import re
from hashlib import md5
import urllib.parse

import cherrypy
from cherrypy._cpcompat import text_or_bytes
from cherrypy.lib import httputil as _httputil
from cherrypy.lib import is_iterator

#                     Conditional HTTP request support                     #

[docs]def validate_etags(autotags=False, debug=False): """Validate the current ETag against If-Match, If-None-Match headers. If autotags is True, an ETag response-header value will be provided from an MD5 hash of the response body (unless some other code has already provided an ETag header). If False (the default), the ETag will not be automatic. WARNING: the autotags feature is not designed for URL's which allow methods other than GET. For example, if a POST to the same URL returns no content, the automatic ETag will be incorrect, breaking a fundamental use for entity tags in a possibly destructive fashion. Likewise, if you raise 304 Not Modified, the response body will be empty, the ETag hash will be incorrect, and your application will break. See :rfc:`2616` Section 14.24. """ response = cherrypy.serving.response # Guard against being run twice. if hasattr(response, 'ETag'): return status, reason, msg = _httputil.valid_status(response.status) etag = response.headers.get('ETag') # Automatic ETag generation. See warning in docstring. if etag: if debug: cherrypy.log('ETag already set: %s' % etag, 'TOOLS.ETAGS') elif not autotags: if debug: cherrypy.log('Autotags off', 'TOOLS.ETAGS') elif status != 200: if debug: cherrypy.log('Status not 200', 'TOOLS.ETAGS') else: etag = response.collapse_body() etag = '"%s"' % md5(etag).hexdigest() if debug: cherrypy.log('Setting ETag: %s' % etag, 'TOOLS.ETAGS') response.headers['ETag'] = etag response.ETag = etag # "If the request would, without the If-Match header field, result in # anything other than a 2xx or 412 status, then the If-Match header # MUST be ignored." if debug: cherrypy.log('Status: %s' % status, 'TOOLS.ETAGS') if status >= 200 and status <= 299: request = cherrypy.serving.request conditions = request.headers.elements('If-Match') or [] conditions = [str(x) for x in conditions] if debug: cherrypy.log('If-Match conditions: %s' % repr(conditions), 'TOOLS.ETAGS') if conditions and not (conditions == ['*'] or etag in conditions): raise cherrypy.HTTPError(412, 'If-Match failed: ETag %r did ' 'not match %r' % (etag, conditions)) conditions = request.headers.elements('If-None-Match') or [] conditions = [str(x) for x in conditions] if debug: cherrypy.log('If-None-Match conditions: %s' % repr(conditions), 'TOOLS.ETAGS') if conditions == ['*'] or etag in conditions: if debug: cherrypy.log('request.method: %s' % request.method, 'TOOLS.ETAGS') if request.method in ('GET', 'HEAD'): raise cherrypy.HTTPRedirect([], 304) else: raise cherrypy.HTTPError(412, 'If-None-Match failed: ETag %r ' 'matched %r' % (etag, conditions))
[docs]def validate_since(): """Validate the current Last-Modified against If-Modified-Since headers. If no code has set the Last-Modified response header, then no validation will be performed. """ response = cherrypy.serving.response lastmod = response.headers.get('Last-Modified') if lastmod: status, reason, msg = _httputil.valid_status(response.status) request = cherrypy.serving.request since = request.headers.get('If-Unmodified-Since') if since and since != lastmod: if (status >= 200 and status <= 299) or status == 412: raise cherrypy.HTTPError(412) since = request.headers.get('If-Modified-Since') if since and since == lastmod: if (status >= 200 and status <= 299) or status == 304: if request.method in ('GET', 'HEAD'): raise cherrypy.HTTPRedirect([], 304) else: raise cherrypy.HTTPError(412)
# Tool code #
[docs]def allow(methods=None, debug=False): """Raise 405 if request.method not in methods (default ['GET', 'HEAD']). The given methods are case-insensitive, and may be in any order. If only one method is allowed, you may supply a single string; if more than one, supply a list of strings. Regardless of whether the current method is allowed or not, this also emits an 'Allow' response header, containing the given methods. """ if not isinstance(methods, (tuple, list)): methods = [methods] methods = [m.upper() for m in methods if m] if not methods: methods = ['GET', 'HEAD'] elif 'GET' in methods and 'HEAD' not in methods: methods.append('HEAD') cherrypy.response.headers['Allow'] = ', '.join(methods) if cherrypy.request.method not in methods: if debug: cherrypy.log('request.method %r not in methods %r' % (cherrypy.request.method, methods), 'TOOLS.ALLOW') raise cherrypy.HTTPError(405) else: if debug: cherrypy.log('request.method %r in methods %r' % (cherrypy.request.method, methods), 'TOOLS.ALLOW')
[docs]def proxy(base=None, local='X-Forwarded-Host', remote='X-Forwarded-For', scheme='X-Forwarded-Proto', debug=False): """Change the base URL (scheme://host[:port][/path]). For running a CP server behind Apache, lighttpd, or other HTTP server. For Apache and lighttpd, you should leave the 'local' argument at the default value of 'X-Forwarded-Host'. For Squid, you probably want to set tools.proxy.local = 'Origin'. If you want the new request.base to include path info (not just the host), you must explicitly set base to the full base path, and ALSO set 'local' to '', so that the X-Forwarded-Host request header (which never includes path info) does not override it. Regardless, the value for 'base' MUST NOT end in a slash. cherrypy.request.remote.ip (the IP address of the client) will be rewritten if the header specified by the 'remote' arg is valid. By default, 'remote' is set to 'X-Forwarded-For'. If you do not want to rewrite remote.ip, set the 'remote' arg to an empty string. """ request = cherrypy.serving.request if scheme: s = request.headers.get(scheme, None) if debug: cherrypy.log('Testing scheme %r:%r' % (scheme, s), 'TOOLS.PROXY') if s == 'on' and 'ssl' in scheme.lower(): # This handles e.g. webfaction's 'X-Forwarded-Ssl: on' header scheme = 'https' else: # This is for lighttpd/pound/Mongrel's 'X-Forwarded-Proto: https' scheme = s if not scheme: scheme = request.base[:request.base.find('://')] if local: lbase = request.headers.get(local, None) if debug: cherrypy.log('Testing local %r:%r' % (local, lbase), 'TOOLS.PROXY') if lbase is not None: base = lbase.split(',')[0] if not base: default = urllib.parse.urlparse(request.base).netloc base = request.headers.get('Host', default) if base.find('://') == -1: # add http:// or https:// if needed base = scheme + '://' + base request.base = base if remote: xff = request.headers.get(remote) if debug: cherrypy.log('Testing remote %r:%r' % (remote, xff), 'TOOLS.PROXY') if xff: if remote == 'X-Forwarded-For': # Grab the first IP in a comma-separated list. Ref #1268. xff = next(ip.strip() for ip in xff.split(',')) request.remote.ip = xff
[docs]def ignore_headers(headers=('Range',), debug=False): """Delete request headers whose field names are included in 'headers'. This is a useful tool for working behind certain HTTP servers; for example, Apache duplicates the work that CP does for 'Range' headers, and will doubly-truncate the response. """ request = cherrypy.serving.request for name in headers: if name in request.headers: if debug: cherrypy.log('Ignoring request header %r' % name, 'TOOLS.IGNORE_HEADERS') del request.headers[name]
[docs]def response_headers(headers=None, debug=False): """Set headers on the response.""" if debug: cherrypy.log('Setting response headers: %s' % repr(headers), 'TOOLS.RESPONSE_HEADERS') for name, value in (headers or []): cherrypy.serving.response.headers[name] = value
response_headers.failsafe = True
[docs]def referer(pattern, accept=True, accept_missing=False, error=403, message='Forbidden Referer header.', debug=False): """Raise HTTPError if Referer header does/does not match the given pattern. pattern A regular expression pattern to test against the Referer. accept If True, the Referer must match the pattern; if False, the Referer must NOT match the pattern. accept_missing If True, permit requests with no Referer header. error The HTTP error code to return to the client on failure. message A string to include in the response body on failure. """ try: ref = cherrypy.serving.request.headers['Referer'] match = bool(re.match(pattern, ref)) if debug: cherrypy.log('Referer %r matches %r' % (ref, pattern), 'TOOLS.REFERER') if accept == match: return except KeyError: if debug: cherrypy.log('No Referer header', 'TOOLS.REFERER') if accept_missing: return raise cherrypy.HTTPError(error, message)
[docs]class SessionAuth(object): """Assert that the user is logged in.""" session_key = 'username' debug = False
[docs] def check_username_and_password(self, username, password): pass
[docs] def anonymous(self): """Provide a temporary user name for anonymous users.""" pass
[docs] def on_login(self, username): pass
[docs] def on_logout(self, username): pass
[docs] def on_check(self, username): pass
[docs] def login_screen(self, from_page='..', username='', error_msg='', **kwargs): return (str("""<html><body> Message: %(error_msg)s <form method="post" action="do_login"> Login: <input type="text" name="username" value="%(username)s" size="10" /> <br /> Password: <input type="password" name="password" size="10" /> <br /> <input type="hidden" name="from_page" value="%(from_page)s" /> <br /> <input type="submit" /> </form> </body></html>""") % vars()).encode('utf-8')
[docs] def do_login(self, username, password, from_page='..', **kwargs): """Login. May raise redirect, or return True if request handled.""" response = cherrypy.serving.response error_msg = self.check_username_and_password(username, password) if error_msg: body = self.login_screen(from_page, username, error_msg) response.body = body if 'Content-Length' in response.headers: # Delete Content-Length header so finalize() recalcs it. del response.headers['Content-Length'] return True else: cherrypy.serving.request.login = username cherrypy.session[self.session_key] = username self.on_login(username) raise cherrypy.HTTPRedirect(from_page or '/')
[docs] def do_logout(self, from_page='..', **kwargs): """Logout. May raise redirect, or return True if request handled.""" sess = cherrypy.session username = sess.get(self.session_key) sess[self.session_key] = None if username: cherrypy.serving.request.login = None self.on_logout(username) raise cherrypy.HTTPRedirect(from_page)
[docs] def do_check(self): """Assert username. Raise redirect, or return True if request handled. """ sess = cherrypy.session request = cherrypy.serving.request response = cherrypy.serving.response username = sess.get(self.session_key) if not username: sess[self.session_key] = username = self.anonymous() self._debug_message('No session[username], trying anonymous') if not username: url = cherrypy.url(qs=request.query_string) self._debug_message( 'No username, routing to login_screen with from_page %(url)r', locals(), ) response.body = self.login_screen(url) if 'Content-Length' in response.headers: # Delete Content-Length header so finalize() recalcs it. del response.headers['Content-Length'] return True self._debug_message('Setting request.login to %(username)r', locals()) request.login = username self.on_check(username)
def _debug_message(self, template, context={}): if not self.debug: return cherrypy.log(template % context, 'TOOLS.SESSAUTH')
[docs] def run(self): request = cherrypy.serving.request response = cherrypy.serving.response path = request.path_info if path.endswith('login_screen'): self._debug_message('routing %(path)r to login_screen', locals()) response.body = self.login_screen() return True elif path.endswith('do_login'): if request.method != 'POST': response.headers['Allow'] = 'POST' self._debug_message('do_login requires POST') raise cherrypy.HTTPError(405) self._debug_message('routing %(path)r to do_login', locals()) return self.do_login(**request.params) elif path.endswith('do_logout'): if request.method != 'POST': response.headers['Allow'] = 'POST' raise cherrypy.HTTPError(405) self._debug_message('routing %(path)r to do_logout', locals()) return self.do_logout(**request.params) else: self._debug_message('No special path, running do_check') return self.do_check()
[docs]def session_auth(**kwargs): """Session authentication hook. Any attribute of the SessionAuth class may be overridden via a keyword arg to this function: """ + '\n '.join( '{!s}: {!s}'.format(k, type(getattr(SessionAuth, k)).__name__) for k in dir(SessionAuth) if not k.startswith('__') ) sa = SessionAuth() for k, v in kwargs.items(): setattr(sa, k, v) return
[docs]def log_traceback(severity=logging.ERROR, debug=False): """Write the last error's traceback to the cherrypy error log.""" cherrypy.log('', 'HTTP', severity=severity, traceback=True)
[docs]def log_request_headers(debug=False): """Write request headers to the cherrypy error log.""" h = [' %s: %s' % (k, v) for k, v in cherrypy.serving.request.header_list] cherrypy.log('\nRequest Headers:\n' + '\n'.join(h), 'HTTP')
[docs]def log_hooks(debug=False): """Write request.hooks to the cherrypy error log.""" request = cherrypy.serving.request msg = [] # Sort by the standard points if possible. from cherrypy import _cprequest points = _cprequest.hookpoints for k in request.hooks.keys(): if k not in points: points.append(k) for k in points: msg.append(' %s:' % k) v = request.hooks.get(k, []) v.sort() for h in v: msg.append(' %r' % h) cherrypy.log('\nRequest Hooks for ' + cherrypy.url() + ':\n' + '\n'.join(msg), 'HTTP')
[docs]def redirect(url='', internal=True, debug=False): """Raise InternalRedirect or HTTPRedirect to the given url.""" if debug: cherrypy.log('Redirecting %sto: %s' % ({True: 'internal ', False: ''}[internal], url), 'TOOLS.REDIRECT') if internal: raise cherrypy.InternalRedirect(url) else: raise cherrypy.HTTPRedirect(url)
[docs]def trailing_slash(missing=True, extra=False, status=None, debug=False): """Redirect if path_info has (missing|extra) trailing slash.""" request = cherrypy.serving.request pi = request.path_info if debug: cherrypy.log('is_index: %r, missing: %r, extra: %r, path_info: %r' % (request.is_index, missing, extra, pi), 'TOOLS.TRAILING_SLASH') if request.is_index is True: if missing: if not pi.endswith('/'): new_url = cherrypy.url(pi + '/', request.query_string) raise cherrypy.HTTPRedirect(new_url, status=status or 301) elif request.is_index is False: if extra: # If pi == '/', don't redirect to ''! if pi.endswith('/') and pi != '/': new_url = cherrypy.url(pi[:-1], request.query_string) raise cherrypy.HTTPRedirect(new_url, status=status or 301)
[docs]def flatten(debug=False): """Wrap response.body in a generator that recursively iterates over body. This allows cherrypy.response.body to consist of 'nested generators'; that is, a set of generators that yield generators. """ def flattener(input): numchunks = 0 for x in input: if not is_iterator(x): numchunks += 1 yield x else: for y in flattener(x): numchunks += 1 yield y if debug: cherrypy.log('Flattened %d chunks' % numchunks, 'TOOLS.FLATTEN') response = cherrypy.serving.response response.body = flattener(response.body)
[docs]def accept(media=None, debug=False): """Return the client's preferred media-type (from the given Content-Types). If 'media' is None (the default), no test will be performed. If 'media' is provided, it should be the Content-Type value (as a string) or values (as a list or tuple of strings) which the current resource can emit. The client's acceptable media ranges (as declared in the Accept request header) will be matched in order to these Content-Type values; the first such string is returned. That is, the return value will always be one of the strings provided in the 'media' arg (or None if 'media' is None). If no match is found, then HTTPError 406 (Not Acceptable) is raised. Note that most web browsers send */* as a (low-quality) acceptable media range, which should match any Content-Type. In addition, "...if no Accept header field is present, then it is assumed that the client accepts all media types." Matching types are checked in order of client preference first, and then in the order of the given 'media' values. Note that this function does not honor accept-params (other than "q"). """ if not media: return if isinstance(media, text_or_bytes): media = [media] request = cherrypy.serving.request # Parse the Accept request header, and try to match one # of the requested media-ranges (in order of preference). ranges = request.headers.elements('Accept') if not ranges: # Any media type is acceptable. if debug: cherrypy.log('No Accept header elements', 'TOOLS.ACCEPT') return media[0] else: # Note that 'ranges' is sorted in order of preference for element in ranges: if element.qvalue > 0: if element.value == '*/*': # Matches any type or subtype if debug: cherrypy.log('Match due to */*', 'TOOLS.ACCEPT') return media[0] elif element.value.endswith('/*'): # Matches any subtype mtype = element.value[:-1] # Keep the slash for m in media: if m.startswith(mtype): if debug: cherrypy.log('Match due to %s' % element.value, 'TOOLS.ACCEPT') return m else: # Matches exact value if element.value in media: if debug: cherrypy.log('Match due to %s' % element.value, 'TOOLS.ACCEPT') return element.value # No suitable media-range found. ah = request.headers.get('Accept') if ah is None: msg = 'Your client did not send an Accept header.' else: msg = 'Your client sent this Accept header: %s.' % ah msg += (' But this resource only emits these media types: %s.' % ', '.join(media)) raise cherrypy.HTTPError(406, msg)
[docs]class MonitoredHeaderMap(_httputil.HeaderMap):
[docs] def transform_key(self, key): self.accessed_headers.add(key) return super(MonitoredHeaderMap, self).transform_key(key)
def __init__(self): self.accessed_headers = set() super(MonitoredHeaderMap, self).__init__()
[docs]def autovary(ignore=None, debug=False): """Auto-populate the Vary response header based on request.header access. """ request = cherrypy.serving.request req_h = request.headers request.headers = MonitoredHeaderMap() request.headers.update(req_h) if ignore is None: ignore = set(['Content-Disposition', 'Content-Length', 'Content-Type']) def set_response_header(): resp_h = cherrypy.serving.response.headers v = set([e.value for e in resp_h.elements('Vary')]) if debug: cherrypy.log( 'Accessed headers: %s' % request.headers.accessed_headers, 'TOOLS.AUTOVARY') v = v.union(request.headers.accessed_headers) v = v.difference(ignore) v = list(v) v.sort() resp_h['Vary'] = ', '.join(v) request.hooks.attach('before_finalize', set_response_header, 95)
[docs]def convert_params(exception=ValueError, error=400): """Convert request params based on function annotations, with error handling. exception Exception class to catch. status The HTTP error code to return to the client on failure. """ request = cherrypy.serving.request types = request.handler.callable.__annotations__ with cherrypy.HTTPError.handle(exception, error): for key in set(types).intersection(request.params): request.params[key] = types[key](request.params[key])