Source code for cherrypy.lib.encoding

import struct
import time
import io

import cherrypy
from cherrypy._cpcompat import text_or_bytes
from cherrypy.lib import file_generator
from cherrypy.lib import is_closable_iterator
from cherrypy.lib import set_vary_header


[docs]def decode(encoding=None, default_encoding='utf-8'): """Replace or extend the list of charsets used to decode a request entity. Either argument may be a single string or a list of strings. encoding If not None, restricts the set of charsets attempted while decoding a request entity to the given set (even if a different charset is given in the Content-Type request header). default_encoding Only in effect if the 'encoding' argument is not given. If given, the set of charsets attempted while decoding a request entity is *extended* with the given value(s). """ body = cherrypy.request.body if encoding is not None: if not isinstance(encoding, list): encoding = [encoding] body.attempt_charsets = encoding elif default_encoding: if not isinstance(default_encoding, list): default_encoding = [default_encoding] body.attempt_charsets = body.attempt_charsets + default_encoding
[docs]class UTF8StreamEncoder: def __init__(self, iterator): self._iterator = iterator def __iter__(self): return self
[docs] def next(self): return self.__next__()
def __next__(self): res = next(self._iterator) if isinstance(res, str): res = res.encode('utf-8') return res
[docs] def close(self): if is_closable_iterator(self._iterator): self._iterator.close()
def __getattr__(self, attr): if attr.startswith('__'): raise AttributeError(self, attr) return getattr(self._iterator, attr)
[docs]class ResponseEncoder: default_encoding = 'utf-8' failmsg = 'Response body could not be encoded with %r.' encoding = None errors = 'strict' text_only = True add_charset = True debug = False def __init__(self, **kwargs): for k, v in kwargs.items(): setattr(self, k, v) self.attempted_charsets = set() request = cherrypy.serving.request if request.handler is not None: # Replace request.handler with self if self.debug: cherrypy.log('Replacing request.handler', 'TOOLS.ENCODE') self.oldhandler = request.handler request.handler = self
[docs] def encode_stream(self, encoding): """Encode a streaming response body. Use a generator wrapper, and just pray it works as the stream is being written out. """ if encoding in self.attempted_charsets: return False self.attempted_charsets.add(encoding) def encoder(body): for chunk in body: if isinstance(chunk, str): chunk = chunk.encode(encoding, self.errors) yield chunk self.body = encoder(self.body) return True
[docs] def encode_string(self, encoding): """Encode a buffered response body.""" if encoding in self.attempted_charsets: return False self.attempted_charsets.add(encoding) body = [] for chunk in self.body: if isinstance(chunk, str): try: chunk = chunk.encode(encoding, self.errors) except (LookupError, UnicodeError): return False body.append(chunk) self.body = body return True
[docs] def find_acceptable_charset(self): request = cherrypy.serving.request response = cherrypy.serving.response if self.debug: cherrypy.log(' %r' %, 'TOOLS.ENCODE') if encoder = self.encode_stream else: encoder = self.encode_string if 'Content-Length' in response.headers: # Delete Content-Length header so finalize() recalcs it. # Encoded strings may be of different lengths from their # unicode equivalents, and even from each other. For example: # >>> t = u"\u7007\u3040" # >>> len(t) # 2 # >>> len(t.encode("UTF-8")) # 6 # >>> len(t.encode("utf7")) # 8 del response.headers['Content-Length'] # Parse the Accept-Charset request header, and try to provide one # of the requested charsets (in order of user preference). encs = request.headers.elements('Accept-Charset') charsets = [enc.value.lower() for enc in encs] if self.debug: cherrypy.log('charsets %s' % repr(charsets), 'TOOLS.ENCODE') if self.encoding is not None: # If specified, force this encoding to be used, or fail. encoding = self.encoding.lower() if self.debug: cherrypy.log('Specified encoding %r' % encoding, 'TOOLS.ENCODE') if (not charsets) or '*' in charsets or encoding in charsets: if self.debug: cherrypy.log('Attempting encoding %r' % encoding, 'TOOLS.ENCODE') if encoder(encoding): return encoding else: if not encs: if self.debug: cherrypy.log('Attempting default encoding %r' % self.default_encoding, 'TOOLS.ENCODE') # Any character-set is acceptable. if encoder(self.default_encoding): return self.default_encoding else: raise cherrypy.HTTPError(500, self.failmsg % self.default_encoding) else: for element in encs: if element.qvalue > 0: if element.value == '*': # Matches any charset. Try our default. if self.debug: cherrypy.log('Attempting default encoding due ' 'to %r' % element, 'TOOLS.ENCODE') if encoder(self.default_encoding): return self.default_encoding else: encoding = element.value if self.debug: cherrypy.log('Attempting encoding %s (qvalue >' '0)' % element, 'TOOLS.ENCODE') if encoder(encoding): return encoding if '*' not in charsets: # If no "*" is present in an Accept-Charset field, then all # character sets not explicitly mentioned get a quality # value of 0, except for ISO-8859-1, which gets a quality # value of 1 if not explicitly mentioned. iso = 'iso-8859-1' if iso not in charsets: if self.debug: cherrypy.log('Attempting ISO-8859-1 encoding', 'TOOLS.ENCODE') if encoder(iso): return iso # No suitable encoding found. ac = request.headers.get('Accept-Charset') if ac is None: msg = 'Your client did not send an Accept-Charset header.' else: msg = 'Your client sent this Accept-Charset header: %s.' % ac _charsets = ', '.join(sorted(self.attempted_charsets)) msg += ' We tried these charsets: %s.' % (_charsets,) raise cherrypy.HTTPError(406, msg)
def __call__(self, *args, **kwargs): response = cherrypy.serving.response self.body = self.oldhandler(*args, **kwargs) self.body = prepare_iter(self.body) ct = response.headers.elements('Content-Type') if self.debug: cherrypy.log('Content-Type: %r' % [str(h) for h in ct], 'TOOLS.ENCODE') if ct and self.add_charset: ct = ct[0] if self.text_only: if ct.value.lower().startswith('text/'): if self.debug: cherrypy.log( 'Content-Type %s starts with "text/"' % ct, 'TOOLS.ENCODE') do_find = True else: if self.debug: cherrypy.log('Not finding because Content-Type %s ' 'does not start with "text/"' % ct, 'TOOLS.ENCODE') do_find = False else: if self.debug: cherrypy.log('Finding because not text_only', 'TOOLS.ENCODE') do_find = True if do_find: # Set "charset=..." param on response Content-Type header ct.params['charset'] = self.find_acceptable_charset() if self.debug: cherrypy.log('Setting Content-Type %s' % ct, 'TOOLS.ENCODE') response.headers['Content-Type'] = str(ct) return self.body
[docs]def prepare_iter(value): """ Ensure response body is iterable and resolves to False when empty. """ if isinstance(value, text_or_bytes): # strings get wrapped in a list because iterating over a single # item list is much faster than iterating over every character # in a long string. if value: value = [value] else: # [''] doesn't evaluate to False, so replace it with []. value = [] # Don't use isinstance here; io.IOBase which has an ABC takes # 1000 times as long as, say, isinstance(value, str) elif hasattr(value, 'read'): value = file_generator(value) elif value is None: value = [] return value
[docs]def compress(body, compress_level): """Compress 'body' at the given compress_level.""" import zlib # See yield b'\x1f\x8b' # ID1 and ID2: gzip marker yield b'\x08' # CM: compression method yield b'\x00' # FLG: none set # MTIME: 4 bytes yield struct.pack('<L', int(time.time()) & int('FFFFFFFF', 16)) # RFC 1952, section 2.3.1: # # XFL (eXtra FLags) # These flags are available for use by specific compression # methods. The "deflate" method (CM = 8) sets these flags as # follows: # # XFL = 2 - compressor used maximum compression, # slowest algorithm # XFL = 4 - compressor used fastest algorithm if compress_level == _COMPRESSION_LEVEL_BEST: yield b'\x02' # XFL: max compression, slowest algo elif compress_level == _COMPRESSION_LEVEL_FAST: yield b'\x04' # XFL: min compression, fastest algo else: yield b'\x00' # XFL: compression unset/tradeoff yield b'\xff' # OS: unknown crc = zlib.crc32(b'') size = 0 zobj = zlib.compressobj(compress_level, zlib.DEFLATED, -zlib.MAX_WBITS, zlib.DEF_MEM_LEVEL, 0) for line in body: size += len(line) crc = zlib.crc32(line, crc) yield zobj.compress(line) yield zobj.flush() # CRC32: 4 bytes yield struct.pack('<L', crc & int('FFFFFFFF', 16)) # ISIZE: 4 bytes yield struct.pack('<L', size & int('FFFFFFFF', 16))
[docs]def decompress(body): import gzip zbuf = io.BytesIO() zbuf.write(body) zfile = gzip.GzipFile(mode='rb', fileobj=zbuf) data = zfile.close() return data
[docs]def gzip(compress_level=5, mime_types=['text/html', 'text/plain'], debug=False): """Try to gzip the response body if Content-Type in mime_types. cherrypy.response.headers['Content-Type'] must be set to one of the values in the mime_types arg before calling this function. The provided list of mime-types must be of one of the following form: * `type/subtype` * `type/*` * `type/*+subtype` No compression is performed if any of the following hold: * The client sends no Accept-Encoding request header * No 'gzip' or 'x-gzip' is present in the Accept-Encoding header * No 'gzip' or 'x-gzip' with a qvalue > 0 is present * The 'identity' value is given with a qvalue > 0. """ request = cherrypy.serving.request response = cherrypy.serving.response set_vary_header(response, 'Accept-Encoding') if not response.body: # Response body is empty (might be a 304 for instance) if debug: cherrypy.log('No response body', context='TOOLS.GZIP') return # If returning cached content (which should already have been gzipped), # don't re-zip. if getattr(request, 'cached', False): if debug: cherrypy.log('Not gzipping cached response', context='TOOLS.GZIP') return acceptable = request.headers.elements('Accept-Encoding') if not acceptable: # If no Accept-Encoding field is present in a request, # the server MAY assume that the client will accept any # content coding. In this case, if "identity" is one of # the available content-codings, then the server SHOULD use # the "identity" content-coding, unless it has additional # information that a different content-coding is meaningful # to the client. if debug: cherrypy.log('No Accept-Encoding', context='TOOLS.GZIP') return ct = response.headers.get('Content-Type', '').split(';')[0] for coding in acceptable: if coding.value == 'identity' and coding.qvalue != 0: if debug: cherrypy.log('Non-zero identity qvalue: %s' % coding, context='TOOLS.GZIP') return if coding.value in ('gzip', 'x-gzip'): if coding.qvalue == 0: if debug: cherrypy.log('Zero gzip qvalue: %s' % coding, context='TOOLS.GZIP') return if ct not in mime_types: # If the list of provided mime-types contains tokens # such as 'text/*' or 'application/*+xml', # we go through them and find the most appropriate one # based on the given content-type. # The pattern matching is only caring about the most # common cases, as stated above, and doesn't support # for extra parameters. found = False if '/' in ct: ct_media_type, ct_sub_type = ct.split('/') for mime_type in mime_types: if '/' in mime_type: media_type, sub_type = mime_type.split('/') if ct_media_type == media_type: if sub_type == '*': found = True break elif '+' in sub_type and '+' in ct_sub_type: ct_left, ct_right = ct_sub_type.split('+') left, right = sub_type.split('+') if left == '*' and ct_right == right: found = True break if not found: if debug: cherrypy.log('Content-Type %s not in mime_types %r' % (ct, mime_types), context='TOOLS.GZIP') return if debug: cherrypy.log('Gzipping', context='TOOLS.GZIP') # Return a generator that compresses the page response.headers['Content-Encoding'] = 'gzip' response.body = compress(response.body, compress_level) if 'Content-Length' in response.headers: # Delete Content-Length header so finalize() recalcs it. del response.headers['Content-Length'] return if debug: cherrypy.log('No acceptable encoding found.', context='GZIP') cherrypy.HTTPError(406, 'identity, gzip').set_response()