static.py

#!/usr/bin/env python
"""static - A stupidly simple WSGI way to serve static (or mixed) content.

(See the docstrings of the various functions and classes.)

Copyright (C) 2006-2009 Luke Arno - http://lukearno.com/

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to:

The Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.

Luke Arno can be found at http://lukearno.com/

"""

import mimetypes
import rfc822
import time
import string
import sys
from os import path, stat, getcwd
from wsgiref import util
from wsgiref.headers import Headers
from wsgiref.simple_server import make_server
from optparse import OptionParser

try: from pkg_resources import resource_filename, Requirement
except: pass

try: import kid
except: pass


class MagicError(Exception): pass


class StatusApp:
 """Used by WSGI apps to return some HTTP status."""

 def __init__(self, status, message=None):
 self.status = status
 if message is None:
 self.message = status
 else:
 self.message = message

 def __call__(self, environ, start_response, headers=[]):
 if self.message:
 Headers(headers).add_header('Content-type', 'text/plain')
 start_response(self.status, headers)
 if environ['REQUEST_METHOD'] == 'HEAD':
 return [""]
 else:
 return [self.message]


class Cling(object):
 """A stupidly simple way to serve static content via WSGI.

 Serve the file of the same path as PATH_INFO in self.datadir.

 Look up the Content-type in self.content_types by extension
 or use 'text/plain' if the extension is not found.

 Serve up the contents of the file or delegate to self.not_found.
 """

 block_size = 16 * 4096
 index_file = 'index.html'
 not_found = StatusApp('404 Not Found')
 not_modified = StatusApp('304 Not Modified', "")
 moved_permanently = StatusApp('301 Moved Permanently')
 method_not_allowed = StatusApp('405 Method Not Allowed')

 def __init__(self, root, **kw):
 """Just set the root and any other attribs passes via **kw."""
 self.root = root
 for k, v in kw.iteritems():
 setattr(self, k, v)

 def __call__(self, environ, start_response):
 """Respond to a request when called in the usual WSGI way."""
 if environ['REQUEST_METHOD'] not in ('GET', 'HEAD'):
 headers = [('Allow', 'GET, HEAD')]
 return self.method_not_allowed(environ, start_response, headers)
 path_info = environ.get('PATH_INFO', '')
 full_path = self._full_path(path_info)
 if not self._is_under_root(full_path):
 return self.not_found(environ, start_response)
 if path.isdir(full_path):
 if full_path[-1] <> '/' or full_path == self.root:
 location = util.request_uri(environ, include_query=False) + '/'
 if environ.get('QUERY_STRING'):
 location += '?' + environ.get('QUERY_STRING')
 headers = [('Location', location)]
 return self.moved_permanently(environ, start_response, headers)
 else:
 full_path = self._full_path(path_info + self.index_file)
 content_type = self._guess_type(full_path)
 try:
 etag, last_modified = self._conditions(full_path, environ)
 headers = [('Date', rfc822.formatdate(time.time())),
 ('Last-Modified', last_modified),
 ('ETag', etag)]
 if_modified = environ.get('HTTP_IF_MODIFIED_SINCE')
 if if_modified and (rfc822.parsedate(if_modified)
 >= rfc822.parsedate(last_modified)):
 return self.not_modified(environ, start_response, headers)
 if_none = environ.get('HTTP_IF_NONE_MATCH')
 if if_none and (if_none == '*' or etag in if_none):
 return self.not_modified(environ, start_response, headers)
 file_like = self._file_like(full_path)
 headers.append(('Content-Type', content_type))
 start_response("200 OK", headers)
 if environ['REQUEST_METHOD'] == 'GET':
 return self._body(full_path, environ, file_like)
 else:
 return ['']
 except (IOError, OSError), e:
 print e
 return self.not_found(environ, start_response)

 def _full_path(self, path_info):
 """Return the full path from which to read."""
 return self.root + path_info

 def _is_under_root(self, full_path):
 """Guard against arbitrary file retrieval."""
 if (path.abspath(full_path) + path.sep)\
 .startswith(path.abspath(self.root) + path.sep):
 return True
 else:
 return False

 def _guess_type(self, full_path):
 """Guess the mime type using the mimetypes module."""
 return mimetypes.guess_type(full_path)[0] or 'text/plain'

 def _conditions(self, full_path, environ):
 """Return a tuple of etag, last_modified by mtime from stat."""
 mtime = stat(full_path).st_mtime
 return str(mtime), rfc822.formatdate(mtime)

 def _file_like(self, full_path):
 """Return the appropriate file object."""
 return open(full_path, 'rb')

 def _body(self, full_path, environ, file_like):
 """Return an iterator over the body of the response."""
 way_to_send = environ.get('wsgi.file_wrapper', iter_and_close)
 return way_to_send(file_like, self.block_size)


def iter_and_close(file_like, block_size):
 """Yield file contents by block then close the file."""
 while 1:
 try:
 block = file_like.read(block_size)
 if block: yield block
 else: raise StopIteration
 except StopIteration, si:
 file_like.close()
 return


def cling_wrap(package_name, dir_name, **kw):
 """Return a Cling that serves from the given package and dir_name.

 This uses pkg_resources.resource_filename which is not the
 recommended way, since it extracts the files.

 I think this works fine unless you have some _very_ serious
 requirements for static content, in which case you probably
 shouldn't be serving it through a WSGI app, IMHO. YMMV.
 """
 resource = Requirement.parse(package_name)
 return Cling(resource_filename(resource, dir_name), **kw)


def command():
 parser = OptionParser(usage="%prog DIR [HOST][:][PORT]",
 version="static 0.3.6")
 options, args = parser.parse_args()
 if len(args) in (1, 2):
 if len(args) == 2:
 parts = args[1].split(":")
 if len(parts) == 1:
 host = parts[0]
 port = None
 elif len(parts) == 2:
 host, port = parts
 else:
 sys.exit("Invalid host:port specification.")
 elif len(args) == 1:
 host, port = None, None
 if not host:
 host = '0.0.0.0'
 if not port:
 port = 8888
 try:
 port = int(port)
 except:
 sys.exit("Invalid host:port specification.")
 app = Cling(args[0])
 try:
 make_server(host, port, app).serve_forever()
 except KeyboardInterrupt, ki:
 print "Cio, baby!"
 except:
 sys.exit("Problem initializing server.")
 else:
 parser.print_help(sys.stderr)
 sys.exit(1)


def test():
 from wsgiref.validate import validator
 app = Cling(getcwd())
 try:
 print "Serving " + getcwd() + " to http://localhost:8888"
 make_server('0.0.0.0', 8888, validator(app)).serve_forever()
 except KeyboardInterrupt, ki:
 print ""
 print "Ciao, baby!"


if __name__ == '__main__':
 test()