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# Copyright 2013 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import hashlib
import logging
import posixpath
import traceback
from branch_utility import BranchUtility
from environment import IsPreviewServer
from file_system import FileNotFoundError
from redirector import Redirector
from servlet import Servlet, Response
from special_paths import SITE_VERIFICATION_FILE
from third_party.motemplate import Motemplate
def _MakeHeaders(content_type, etag=None):
headers = {
# See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9.1.
'Cache-Control': 'public, max-age=0, no-cache',
'Content-Type': content_type,
'X-Frame-Options': 'sameorigin',
}
if etag is not None:
headers['ETag'] = etag
return headers
class RenderServlet(Servlet):
'''Servlet which renders templates.
'''
class Delegate(object):
def CreateServerInstance(self):
raise NotImplementedError(self.__class__)
def __init__(self, request, delegate):
Servlet.__init__(self, request)
self._delegate = delegate
def Get(self):
''' Render the page for a request.
'''
path = self._request.path.lstrip('/')
# The server used to be partitioned based on Chrome channel, but it isn't
# anymore. Redirect from the old state.
channel_name, path = BranchUtility.SplitChannelNameFromPath(path)
if channel_name is not None:
return Response.Redirect('/' + path, permanent=True)
server_instance = self._delegate.CreateServerInstance()
try:
return self._GetSuccessResponse(path, server_instance)
except FileNotFoundError:
# Find the closest 404.html file and serve that, e.g. if the path is
# extensions/manifest/typo.html then first look for
# extensions/manifest/404.html, then extensions/404.html, then 404.html.
#
# Failing that just print 'Not Found' but that should preferrably never
# happen, because it would look really bad.
path_components = path.split('/')
for i in xrange(len(path_components) - 1, -1, -1):
try:
path_404 = posixpath.join(*(path_components[0:i] + ['404']))
response = self._GetSuccessResponse(path_404, server_instance)
if response.status != 200:
continue
return Response.NotFound(response.content.ToString(),
headers=response.headers)
except FileNotFoundError: continue
logging.warning('No 404.html found in %s' % path)
return Response.NotFound('Not Found', headers=_MakeHeaders('text/plain'))
def _GetSuccessResponse(self, request_path, server_instance):
'''Returns the Response from trying to render |path| with
|server_instance|. If |path| isn't found then a FileNotFoundError will be
raised, such that the only responses that will be returned from this method
are Ok and Redirect.
'''
content_provider, serve_from, path = (
server_instance.content_providers.GetByServeFrom(request_path))
assert content_provider, 'No ContentProvider found for %s' % path
redirect = Redirector(
server_instance.compiled_fs_factory,
content_provider.file_system).Redirect(self._request.host, path)
if redirect is not None:
# Absolute redirects stay absolute, relative redirects are relative to
# |serve_from|; all redirects eventually need to be *served* as absolute.
if not redirect.startswith(('/', 'http://', 'https://')):
redirect = '/' + posixpath.join(serve_from, redirect)
return Response.Redirect(redirect, permanent=False)
canonical_path = content_provider.GetCanonicalPath(path)
if canonical_path != path:
redirect_path = posixpath.join(serve_from, canonical_path)
return Response.Redirect('/' + redirect_path, permanent=False)
if request_path.endswith('/'):
# Directory request hasn't been redirected by now. Default behaviour is
# to redirect as though it were a file.
return Response.Redirect('/' + request_path.rstrip('/'),
permanent=False)
content_and_type = content_provider.GetContentAndType(path).Get()
if not content_and_type.content:
logging.error('%s had empty content' % path)
content = content_and_type.content
if isinstance(content, Motemplate):
template_content, template_warnings = (
server_instance.template_renderer.Render(content, self._request))
# HACK: the site verification file (google2ed...) doesn't have a title.
content, doc_warnings = server_instance.document_renderer.Render(
template_content,
path,
render_title=path != SITE_VERIFICATION_FILE)
warnings = template_warnings + doc_warnings
if warnings:
sep = '\n - '
logging.warning('Rendering %s:%s%s' % (path, sep, sep.join(warnings)))
# Content was dynamic. The new etag is a hash of the content.
etag = None
elif content_and_type.version is not None:
# Content was static. The new etag is the version of the content. Hash it
# to make sure it's valid.
etag = '"%s"' % hashlib.md5(str(content_and_type.version)).hexdigest()
else:
# Sometimes non-dynamic content does not have a version, for example
# .zip files. The new etag is a hash of the content.
etag = None
content_type = content_and_type.content_type
if isinstance(content, unicode):
content = content.encode('utf-8')
content_type += '; charset=utf-8'
if etag is None:
# Note: we're using md5 as a convenient and fast-enough way to identify
# content. It's not intended to be cryptographic in any way, and this
# is *not* what etags is for. That's what SSL is for, this is unrelated.
etag = '"%s"' % hashlib.md5(content).hexdigest()
headers = _MakeHeaders(content_type, etag=etag)
if etag == self._request.headers.get('If-None-Match'):
return Response.NotModified('Not Modified', headers=headers)
return Response.Ok(content, headers=headers)
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