redirector.py revision 2385ea399aae016c0806a4f9ef3c9cfe3d2a39df 
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 posixpath
6from urlparse import urlsplit
7
8from file_system import FileNotFoundError
9from third_party.json_schema_compiler.json_parse import Parse
10
11class Redirector(object):
12  def __init__(self, compiled_fs_factory, file_system, root_path):
13    self._root_path = root_path
14    self._file_system = file_system
15    self._cache = compiled_fs_factory.Create(
16        lambda _, rules: Parse(rules), Redirector)
17
18  def Redirect(self, host, path):
19    ''' Check if a path should be redirected, first according to host
20    redirection rules, then from rules in redirects.json files.
21
22    Returns the path that should be redirected to, or None if no redirection
23    should occur.
24    '''
25    return self._RedirectOldHosts(host, path) or self._RedirectFromConfig(path)
26
27  def _RedirectFromConfig(self, url):
28    ''' Lookup the redirects configuration file in the directory that contains
29    the requested resource. If no redirection rule is matched, or no
30    configuration file exists, returns None.
31    '''
32    dirname, filename = posixpath.split(url)
33
34    try:
35      rules = self._cache.GetFromFile(
36          posixpath.join(self._root_path, dirname, 'redirects.json'))
37    except FileNotFoundError:
38      return None
39
40    redirect = rules.get(filename)
41    if redirect is None:
42      return None
43    if (redirect.startswith('/') or
44        urlsplit(redirect).scheme in ('http', 'https')):
45      return redirect
46
47    return posixpath.normpath('/' + posixpath.join(dirname, redirect))
48
49  def _RedirectOldHosts(self, host, path):
50    ''' Redirect paths from the old code.google.com to the new
51    developer.chrome.com, retaining elements like the channel and https, if
52    used.
53    '''
54    if urlsplit(host).hostname != 'code.google.com':
55      return None
56
57    path = path.split('/')
58    if path and path[0] == 'chrome':
59      path.pop(0)
60
61    return 'https://developer.chrome.com/' + posixpath.join(*path)
62
63  def Cron(self):
64    ''' Load files during a cron run.
65    '''
66    for root, dirs, files in self._file_system.Walk(self._root_path):
67      if 'redirects.json' in files:
68        self._cache.GetFromFile('%s/redirects.json' % posixpath.join(
69            self._root_path, root).rstrip('/'))
70