EVOLUTION-MANAGER

Edit File: formparser.py

# -*- coding: utf-8 -*- """ werkzeug.formparser ~~~~~~~~~~~~~~~~~~~ This module implements the form parsing. It supports url-encoded forms as well as non-nested multipart uploads. :copyright: (c) 2013 by the Werkzeug Team, see AUTHORS for more details. :license: BSD, see LICENSE for more details. """ import re import codecs from io import BytesIO from tempfile import TemporaryFile from itertools import chain, repeat, tee from functools import update_wrapper from werkzeug._compat import to_native, text_type from werkzeug.urls import url_decode_stream from werkzeug.wsgi import make_line_iter, \ get_input_stream, get_content_length from werkzeug.datastructures import Headers, FileStorage, MultiDict from werkzeug.http import parse_options_header #: an iterator that yields empty strings _empty_string_iter = repeat('') #: a regular expression for multipart boundaries _multipart_boundary_re = re.compile('^[ -~]{0,200}[!-~]$') #: supported http encodings that are also available in python we support #: for multipart messages. _supported_multipart_encodings = frozenset(['base64', 'quoted-printable']) def default_stream_factory(total_content_length, filename, content_type, content_length=None): """The stream factory that is used per default.""" if total_content_length > 1024 * 500: return TemporaryFile('wb+') return BytesIO() def parse_form_data(environ, stream_factory=None, charset='utf-8', errors='replace', max_form_memory_size=None, max_content_length=None, cls=None, silent=True): """Parse the form data in the environ and return it as tuple in the form ``(stream, form, files)``. You should only call this method if the transport method is `POST`, `PUT`, or `PATCH`. If the mimetype of the data transmitted is `multipart/form-data` the files multidict will be filled with `FileStorage` objects. If the mimetype is unknown the input stream is wrapped and returned as first argument, else the stream is empty. This is a shortcut for the common usage of :class:`FormDataParser`. Have a look at :ref:`dealing-with-request-data` for more details. .. versionadded:: 0.5 The `max_form_memory_size`, `max_content_length` and `cls` parameters were added. .. versionadded:: 0.5.1 The optional `silent` flag was added. :param environ: the WSGI environment to be used for parsing. :param stream_factory: An optional callable that returns a new read and writeable file descriptor. This callable works the same as :meth:`~BaseResponse._get_file_stream`. :param charset: The character set for URL and url encoded form data. :param errors: The encoding error behavior. :param max_form_memory_size: the maximum number of bytes to be accepted for in-memory stored form data. If the data exceeds the value specified an :exc:`~exceptions.RequestEntityTooLarge` exception is raised. :param max_content_length: If this is provided and the transmitted data is longer than this value an :exc:`~exceptions.RequestEntityTooLarge` exception is raised. :param cls: an optional dict class to use. If this is not specified or `None` the default :class:`MultiDict` is used. :param silent: If set to False parsing errors will not be caught. :return: A tuple in the form ``(stream, form, files)``. """ return FormDataParser(stream_factory, charset, errors, max_form_memory_size, max_content_length, cls, silent).parse_from_environ(environ) def exhaust_stream(f): """Helper decorator for methods that exhausts the stream on return.""" def wrapper(self, stream, *args, **kwargs): try: return f(self, stream, *args, **kwargs) finally: exhaust = getattr(stream, 'exhaust', None) if exhaust is not None: exhaust() else: while 1: chunk = stream.read(1024 * 64) if not chunk: break return update_wrapper(wrapper, f) class FormDataParser(object): """This class implements parsing of form data for Werkzeug. By itself it can parse multipart and url encoded form data. It can be subclassed and extended but for most mimetypes it is a better idea to use the untouched stream and expose it as separate attributes on a request object. .. versionadded:: 0.8 :param stream_factory: An optional callable that returns a new read and writeable file descriptor. This callable works the same as :meth:`~BaseResponse._get_file_stream`. :param charset: The character set for URL and url encoded form data. :param errors: The encoding error behavior. :param max_form_memory_size: the maximum number of bytes to be accepted for in-memory stored form data. If the data exceeds the value specified an :exc:`~exceptions.RequestEntityTooLarge` exception is raised. :param max_content_length: If this is provided and the transmitted data is longer than this value an :exc:`~exceptions.RequestEntityTooLarge` exception is raised. :param cls: an optional dict class to use. If this is not specified or `None` the default :class:`MultiDict` is used. :param silent: If set to False parsing errors will not be caught. """ def __init__(self, stream_factory=None, charset='utf-8', errors='replace', max_form_memory_size=None, max_content_length=None, cls=None, silent=True): if stream_factory is None: stream_factory = default_stream_factory self.stream_factory = stream_factory self.charset = charset self.errors = errors self.max_form_memory_size = max_form_memory_size self.max_content_length = max_content_length if cls is None: cls = MultiDict self.cls = cls self.silent = silent def get_parse_func(self, mimetype, options): return self.parse_functions.get(mimetype) def parse_from_environ(self, environ): """Parses the information from the environment as form data. :param environ: the WSGI environment to be used for parsing. :return: A tuple in the form ``(stream, form, files)``. """ content_type = environ.get('CONTENT_TYPE', '') content_length = get_content_length(environ) mimetype, options = parse_options_header(content_type) return self.parse(get_input_stream(environ), mimetype, content_length, options) def parse(self, stream, mimetype, content_length, options=None): """Parses the information from the given stream, mimetype, content length and mimetype parameters. :param stream: an input stream :param mimetype: the mimetype of the data :param content_length: the content length of the incoming data :param options: optional mimetype parameters (used for the multipart boundary for instance) :return: A tuple in the form ``(stream, form, files)``. """ if self.max_content_length is not None and \ content_length is not None and \ content_length > self.max_content_length: raise exceptions.RequestEntityTooLarge() if options is None: options = {} parse_func = self.get_parse_func(mimetype, options) if parse_func is not None: try: return parse_func(self, stream, mimetype, content_length, options) except ValueError: if not self.silent: raise return stream, self.cls(), self.cls() @exhaust_stream def _parse_multipart(self, stream, mimetype, content_length, options): parser = MultiPartParser(self.stream_factory, self.charset, self.errors, max_form_memory_size=self.max_form_memory_size, cls=self.cls) boundary = options.get('boundary') if isinstance(boundary, text_type): boundary = boundary.encode('ascii') form, files = parser.parse(stream, boundary, content_length) return stream, form, files @exhaust_stream def _parse_urlencoded(self, stream, mimetype, content_length, options): if self.max_form_memory_size is not None and \ content_length is not None and \ content_length > self.max_form_memory_size: raise exceptions.RequestEntityTooLarge() form = url_decode_stream(stream, self.charset, errors=self.errors, cls=self.cls) return stream, form, self.cls() #: mapping of mimetypes to parsing functions parse_functions = { 'multipart/form-data': _parse_multipart, 'application/x-www-form-urlencoded': _parse_urlencoded, 'application/x-url-encoded': _parse_urlencoded } def is_valid_multipart_boundary(boundary): """Checks if the string given is a valid multipart boundary.""" return _multipart_boundary_re.match(boundary) is not None def _line_parse(line): """Removes line ending characters and returns a tuple (`stripped_line`, `is_terminated`). """ if line[-2:] in ['\r\n', b'\r\n']: return line[:-2], True elif line[-1:] in ['\r', '\n', b'\r', b'\n']: return line[:-1], True return line, False def parse_multipart_headers(iterable): """Parses multipart headers from an iterable that yields lines (including the trailing newline symbol). The iterable has to be newline terminated. The iterable will stop at the line where the headers ended so it can be further consumed. :param iterable: iterable of strings that are newline terminated """ result = [] for line in iterable: line = to_native(line) line, line_terminated = _line_parse(line) if not line_terminated: raise ValueError('unexpected end of line in multipart header') if not line: break elif line[0] in ' \t' and result: key, value = result[-1] result[-1] = (key, value + '\n ' + line[1:]) else: parts = line.split(':', 1) if len(parts) == 2: result.append((parts[0].strip(), parts[1].strip())) # we link the list to the headers, no need to create a copy, the # list was not shared anyways. return Headers(result) _begin_form = 'begin_form' _begin_file = 'begin_file' _cont = 'cont' _end = 'end' class MultiPartParser(object): def __init__(self, stream_factory=None, charset='utf-8', errors='replace', max_form_memory_size=None, cls=None, buffer_size=64 * 1024): self.stream_factory = stream_factory self.charset = charset self.errors = errors self.max_form_memory_size = max_form_memory_size if stream_factory is None: stream_factory = default_stream_factory if cls is None: cls = MultiDict self.cls = cls # make sure the buffer size is divisible by four so that we can base64 # decode chunk by chunk assert buffer_size % 4 == 0, 'buffer size has to be divisible by 4' # also the buffer size has to be at least 1024 bytes long or long headers # will freak out the system assert buffer_size >= 1024, 'buffer size has to be at least 1KB' self.buffer_size = buffer_size def _fix_ie_filename(self, filename): """Internet Explorer 6 transmits the full file name if a file is uploaded. This function strips the full path if it thinks the filename is Windows-like absolute. """ if filename[1:3] == ':\\' or filename[:2] == '\\\\': return filename.split('\\')[-1] return filename def _find_terminator(self, iterator): """The terminator might have some additional newlines before it. There is at least one application that sends additional newlines before headers (the python setuptools package). """ for line in iterator: if not line: break line = line.strip() if line: return line return b'' def fail(self, message): raise ValueError(message) def get_part_encoding(self, headers): transfer_encoding = headers.get('content-transfer-encoding') if transfer_encoding is not None and \ transfer_encoding in _supported_multipart_encodings: return transfer_encoding def get_part_charset(self, headers): # Figure out input charset for current part content_type = headers.get('content-type') if content_type: mimetype, ct_params = parse_options_header(content_type) return ct_params.get('charset', self.charset) return self.charset def start_file_streaming(self, filename, headers, total_content_length): if isinstance(filename, bytes): filename = filename.decode(self.charset, self.errors) filename = self._fix_ie_filename(filename) content_type = headers.get('content-type') try: content_length = int(headers['content-length']) except (KeyError, ValueError): content_length = 0 container = self.stream_factory(total_content_length, content_type, filename, content_length) return filename, container def in_memory_threshold_reached(self, bytes): raise exceptions.RequestEntityTooLarge() def validate_boundary(self, boundary): if not boundary: self.fail('Missing boundary') if not is_valid_multipart_boundary(boundary): self.fail('Invalid boundary: %s' % boundary) if len(boundary) > self.buffer_size: # pragma: no cover # this should never happen because we check for a minimum size # of 1024 and boundaries may not be longer than 200. The only # situation when this happens is for non debug builds where # the assert is skipped. self.fail('Boundary longer than buffer size') def parse_lines(self, file, boundary, content_length): """Generate parts of ``('begin_form', (headers, name))`` ``('begin_file', (headers, name, filename))`` ``('cont', bytestring)`` ``('end', None)`` Always obeys the grammar parts = ( begin_form cont* end | begin_file cont* end )* """ next_part = b'--' + boundary last_part = next_part + b'--' iterator = chain(make_line_iter(file, limit=content_length, buffer_size=self.buffer_size), _empty_string_iter) terminator = self._find_terminator(iterator) if terminator == last_part: return elif terminator != next_part: self.fail('Expected boundary at start of multipart data') while terminator != last_part: headers = parse_multipart_headers(iterator) disposition = headers.get('content-disposition') if disposition is None: self.fail('Missing Content-Disposition header') disposition, extra = parse_options_header(disposition) transfer_encoding = self.get_part_encoding(headers) name = extra.get('name') filename = extra.get('filename') # if no content type is given we stream into memory. A list is # used as a temporary container. if filename is None: yield _begin_form, (headers, name) # otherwise we parse the rest of the headers and ask the stream # factory for something we can write in. else: yield _begin_file, (headers, name, filename) buf = b'' for line in iterator: if not line: self.fail('unexpected end of stream') if line[:2] == b'--': terminator = line.rstrip() if terminator in (next_part, last_part): break if transfer_encoding is not None: if transfer_encoding == 'base64': transfer_encoding = 'base64_codec' try: line = codecs.decode(line, transfer_encoding) except Exception: self.fail('could not decode transfer encoded chunk') # we have something in the buffer from the last iteration. # this is usually a newline delimiter. if buf: yield _cont, buf buf = b'' # If the line ends with windows CRLF we write everything except # the last two bytes. In all other cases however we write # everything except the last byte. If it was a newline, that's # fine, otherwise it does not matter because we will write it # the next iteration. this ensures we do not write the # final newline into the stream. That way we do not have to # truncate the stream. However we do have to make sure that # if something else than a newline is in there we write it # out. if line[-2:] == b'\r\n': buf = b'\r\n' cutoff = -2 else: buf = line[-1:] cutoff = -1 yield _cont, line[:cutoff] else: # pragma: no cover raise ValueError('unexpected end of part') # if we have a leftover in the buffer that is not a newline # character we have to flush it, otherwise we will chop of # certain values. if buf not in (b'', b'\r', b'\n', b'\r\n'): yield _cont, buf yield _end, None def parse_parts(self, file, boundary, content_length): """Generate ``('file', (name, val))`` and ``('form', (name, val))`` parts. """ in_memory = 0 for ellt, ell in self.parse_lines(file, boundary, content_length): if ellt == _begin_file: headers, name, filename = ell is_file = True guard_memory = False filename, container = self.start_file_streaming( filename, headers, content_length) _write = container.write elif ellt == _begin_form: headers, name = ell is_file = False container = [] _write = container.append guard_memory = self.max_form_memory_size is not None elif ellt == _cont: _write(ell) # if we write into memory and there is a memory size limit we # count the number of bytes in memory and raise an exception if # there is too much data in memory. if guard_memory: in_memory += len(ell) if in_memory > self.max_form_memory_size: self.in_memory_threshold_reached(in_memory) elif ellt == _end: if is_file: container.seek(0) yield ('file', (name, FileStorage(container, filename, name, headers=headers))) else: part_charset = self.get_part_charset(headers) yield ('form', (name, b''.join(container).decode( part_charset, self.errors))) def parse(self, file, boundary, content_length): formstream, filestream = tee( self.parse_parts(file, boundary, content_length), 2) form = (p[1] for p in formstream if p[0] == 'form') files = (p[1] for p in filestream if p[0] == 'file') return self.cls(form), self.cls(files) from werkzeug import exceptions