package_cache/server.py

   1 # Copyright
   2
   3 import email.utils as _email_utils
   4 import mimetypes as _mimetypes
   5 import os as _os
   6 import urllib.parse as _urllib_parse
   7
   8
   9 class InvalidFile (ValueError):
  10     def __init__(self, url):
  11         super(InvalidFile, self).__init__('invalid file {!r}'.format(url))
  12         self.url = url
  13
  14
  15 class Server (object):
  16     def __init__(self, sources, cache):
  17         self.sources = sources
  18         self.cache = cache
  19         if not _os.path.isdir(self.cache):
  20             _os.makedirs(self.cache, exist_ok=True)
  21
  22     def __call__(self, environ, start_response):
  23         try:
  24             return self._serve_request(
  25                 environ=environ, start_response=start_response)
  26         except InvalidFile:
  27             start_response('404 Not Found', [])
  28
  29     def _serve_request(self, environ, start_response):
  30         method = environ['REQUEST_METHOD']
  31         url = environ.get('PATH_INFO', None)
  32         if url is None:
  33             raise InvalidFile(url=url)
  34         parsed_url = _urllib_parse.urlparse(url)
  35         relative_path = parsed_url.path.lstrip('/').replace('/', _os.path.sep)
  36         cache_path = _os.path.join(self.cache, relative_path)
  37         if not _os.path.exists(path=cache_path):
  38             self._get_file(url=url, path=cache_path)
  39         if not _os.path.isfile(path=cache_path):
  40             raise InvalidFile(url=url)
  41         return self._serve_file(
  42             path=cache_path, environ=environ, start_response=start_response)
  43
  44     def _get_file(self, url, path):
  45         raise NotImplementedError()
  46
  47     def _serve_file(self, path, environ, start_response):
  48         headers = {
  49             'Content-Length': self._get_content_length(path=path),
  50             'Content-Type': self._get_content_type(path=path),
  51             'Last-Modified': self._get_last_modified(path=path),
  52             }
  53         f = open(path, 'rb')
  54         if 'wsgi.file_wrapper' in environ:
  55             file_iterator = environ['wsgi.file_wrapper'](f)
  56         else:
  57             file_iterator = iter(lambda: f.read(block_size), '')
  58         start_response('200 OK', list(headers.items()))
  59         return file_iterator
  60
  61     def _get_content_length(self, path):
  62         """Content-Length value per RFC 2616
  63
  64         Content-Length:
  65           https://tools.ietf.org/html/rfc2616#section-14.13
  66         """
  67         return str(_os.path.getsize(path))
  68
  69     def _get_content_type(self, path):
  70         """Content-Type value per RFC 2616
  71
  72         Content-Type:
  73           https://tools.ietf.org/html/rfc2616#section-14.17
  74         Media types:
  75           https://tools.ietf.org/html/rfc2616#section-3.7
  76         """
  77         mimetype, charset = _mimetypes.guess_type(url=path)
  78         if charset:
  79             return '{}; charset={}'.format(mimetype, charset)
  80         else:
  81             return mimetype
  82
  83     def _get_last_modified(self, path):
  84         """Last-Modified value per RFC 2616
  85
  86         Last-Modified:
  87           https://tools.ietf.org/html/rfc2616#section-14.29
  88         Date formats:
  89           https://tools.ietf.org/html/rfc2616#section-3.3.1
  90           https://tools.ietf.org/html/rfc1123#page-55
  91           https://tools.ietf.org/html/rfc822#section-5
  92         """
  93         mtime = _os.path.getmtime(path)
  94         return _email_utils.formatdate(
  95             timeval=mtime, localtime=False, usegmt=True)