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1# Copyright 2013 The Chromium Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5import logging
6import posixpath
7import traceback
8
9from environment import IsPreviewServer
10from file_system import FileNotFoundError
11from redirector import Redirector
12from servlet import Servlet, Response
13from third_party.handlebar import Handlebar
14
15
16def _MakeHeaders(content_type):
17  return {
18    'X-Frame-Options': 'sameorigin',
19    'Content-Type': content_type,
20    'Cache-Control': 'max-age=300',
21  }
22
23
24class RenderServlet(Servlet):
25  '''Servlet which renders templates.
26  '''
27
28  class Delegate(object):
29    def CreateServerInstance(self):
30      raise NotImplementedError(self.__class__)
31
32  def __init__(self, request, delegate):
33    Servlet.__init__(self, request)
34    self._delegate = delegate
35
36  def Get(self):
37    ''' Render the page for a request.
38    '''
39    # TODO(kalman): a consistent path syntax (even a Path class?) so that we
40    # can stop being so conservative with stripping and adding back the '/'s.
41    path = self._request.path.lstrip('/')
42    server_instance = self._delegate.CreateServerInstance()
43
44    try:
45      return self._GetSuccessResponse(path, server_instance)
46    except FileNotFoundError:
47      if IsPreviewServer():
48        logging.error(traceback.format_exc())
49      # Maybe it didn't find the file because its canonical location is
50      # somewhere else; this is distinct from "redirects", which are typically
51      # explicit. This is implicit.
52      canonical_result = server_instance.path_canonicalizer.Canonicalize(path)
53      redirect = canonical_result.path.lstrip('/')
54      if path != redirect:
55        return Response.Redirect('/' + redirect,
56                                 permanent=canonical_result.permanent)
57
58      # Not found for reals. Find the closest 404.html file and serve that;
59      # e.g. if the path is extensions/manifest/typo.html then first look for
60      # extensions/manifest/404.html, then extensions/404.html, then 404.html.
61      #
62      # Failing that just print 'Not Found' but that should preferrably never
63      # happen, because it would look really bad.
64      path_components = path.split('/')
65      for i in xrange(len(path_components) - 1, -1, -1):
66        try:
67          path_404 = posixpath.join(*(path_components[0:i] + ['404.html']))
68          response = self._GetSuccessResponse(path_404, server_instance)
69          return Response.NotFound(response.content.ToString(),
70                                   headers=response.headers)
71        except FileNotFoundError: continue
72      logging.warning('No 404.html found in %s' % path)
73      return Response.NotFound('Not Found', headers=_MakeHeaders('text/plain'))
74
75  def _GetSuccessResponse(self, path, server_instance):
76    '''Returns the Response from trying to render |path| with
77    |server_instance|.  If |path| isn't found then a FileNotFoundError will be
78    raised, such that the only responses that will be returned from this method
79    are Ok and Redirect.
80    '''
81    content_provider, path = (
82        server_instance.content_providers.GetByServeFrom(path))
83    assert content_provider, 'No ContentProvider found for %s' % path
84
85    redirect = Redirector(
86        server_instance.compiled_fs_factory,
87        content_provider.file_system).Redirect(self._request.host, path)
88    if redirect is not None:
89      return Response.Redirect(redirect, permanent=False)
90
91    content_and_type = content_provider.GetContentAndType(path).Get()
92    if not content_and_type.content:
93      logging.error('%s had empty content' % path)
94
95    content = content_and_type.content
96    if isinstance(content, Handlebar):
97      template_content, template_warnings = (
98          server_instance.template_renderer.Render(content, self._request))
99      # HACK: the Google ID thing (google2ed...) doesn't have a title.
100      content, doc_warnings = server_instance.document_renderer.Render(
101          template_content,
102          render_title=path != 'google2ed1af765c529f57.html')
103      warnings = template_warnings + doc_warnings
104      if warnings:
105        sep = '\n - '
106        logging.warning('Rendering %s:%s%s' % (path, sep, sep.join(warnings)))
107
108    content_type = content_and_type.content_type
109    if isinstance(content, unicode):
110      content = content.encode('utf-8')
111      content_type += '; charset=utf-8'
112
113    return Response.Ok(content, headers=_MakeHeaders(content_type))
114