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python3.8
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email
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contentmanager.py
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import binascii import email.charset import email.message import email.errors from email import quoprimime class ContentManager: def __init__(self): self.get_handlers = {} self.set_handlers = {} def add_get_handler(self, key, handler): self.get_handlers[key] = handler def get_content(self, msg, *args, **kw): content_type = msg.get_content_type() if content_type in self.get_handlers: return self.get_handlers[content_type](msg, *args, **kw) maintype = msg.get_content_maintype() if maintype in self.get_handlers: return self.get_handlers[maintype](msg, *args, **kw) if '' in self.get_handlers: return self.get_handlers[''](msg, *args, **kw) raise KeyError(content_type) def add_set_handler(self, typekey, handler): self.set_handlers[typekey] = handler def set_content(self, msg, obj, *args, **kw): if msg.get_content_maintype() == 'multipart': # XXX: is this error a good idea or not? We can remove it later, # but we can't add it later, so do it for now. raise TypeError("set_content not valid on multipart") handler = self._find_set_handler(msg, obj) msg.clear_content() handler(msg, obj, *args, **kw) def _find_set_handler(self, msg, obj): full_path_for_error = None for typ in type(obj).__mro__: if typ in self.set_handlers: return self.set_handlers[typ] qname = typ.__qualname__ modname = getattr(typ, '__module__', '') full_path = '.'.join((modname, qname)) if modname else qname if full_path_for_error is None: full_path_for_error = full_path if full_path in self.set_handlers: return self.set_handlers[full_path] if qname in self.set_handlers: return self.set_handlers[qname] name = typ.__name__ if name in self.set_handlers: return self.set_handlers[name] if None in self.set_handlers: return self.set_handlers[None] raise KeyError(full_path_for_error) raw_data_manager = ContentManager() def get_text_content(msg, errors='replace'): content = msg.get_payload(decode=True) charset = msg.get_param('charset', 'ASCII') return content.decode(charset, errors=errors) raw_data_manager.add_get_handler('text', get_text_content) def get_non_text_content(msg): return msg.get_payload(decode=True) for maintype in 'audio image video application'.split(): raw_data_manager.add_get_handler(maintype, get_non_text_content) def get_message_content(msg): return msg.get_payload(0) for subtype in 'rfc822 external-body'.split(): raw_data_manager.add_get_handler('message/'+subtype, get_message_content) def get_and_fixup_unknown_message_content(msg): # If we don't understand a message subtype, we are supposed to treat it as # if it were application/octet-stream, per # tools.ietf.org/html/rfc2046#section-5.2.4. Feedparser doesn't do that, # so do our best to fix things up. Note that it is *not* appropriate to # model message/partial content as Message objects, so they are handled # here as well. (How to reassemble them is out of scope for this comment :) return bytes(msg.get_payload(0)) raw_data_manager.add_get_handler('message', get_and_fixup_unknown_message_content) def _prepare_set(msg, maintype, subtype, headers): msg['Content-Type'] = '/'.join((maintype, subtype)) if headers: if not hasattr(headers[0], 'name'): mp = msg.policy headers = [mp.header_factory(*mp.header_source_parse([header])) for header in headers] try: for header in headers: if header.defects: raise header.defects[0] msg[header.name] = header except email.errors.HeaderDefect as exc: raise ValueError("Invalid header: {}".format( header.fold(policy=msg.policy))) from exc def _finalize_set(msg, disposition, filename, cid, params): if disposition is None and filename is not None: disposition = 'attachment' if disposition is not None: msg['Content-Disposition'] = disposition if filename is not None: msg.set_param('filename', filename, header='Content-Disposition', replace=True) if cid is not None: msg['Content-ID'] = cid if params is not None: for key, value in params.items(): msg.set_param(key, value) # XXX: This is a cleaned-up version of base64mime.body_encode (including a bug # fix in the calculation of unencoded_bytes_per_line). It would be nice to # drop both this and quoprimime.body_encode in favor of enhanced binascii # routines that accepted a max_line_length parameter. def _encode_base64(data, max_line_length): encoded_lines = [] unencoded_bytes_per_line = max_line_length // 4 * 3 for i in range(0, len(data), unencoded_bytes_per_line): thisline = data[i:i+unencoded_bytes_per_line] encoded_lines.append(binascii.b2a_base64(thisline).decode('ascii')) return ''.join(encoded_lines) def _encode_text(string, charset, cte, policy): lines = string.encode(charset).splitlines() linesep = policy.linesep.encode('ascii') def embedded_body(lines): return linesep.join(lines) + linesep def normal_body(lines): return b'\n'.join(lines) + b'\n' if cte==None: # Use heuristics to decide on the "best" encoding. if max((len(x) for x in lines), default=0) <= policy.max_line_length: try: return '7bit', normal_body(lines).decode('ascii') except UnicodeDecodeError: pass if policy.cte_type == '8bit': return '8bit', normal_body(lines).decode('ascii', 'surrogateescape') sniff = embedded_body(lines[:10]) sniff_qp = quoprimime.body_encode(sniff.decode('latin-1'), policy.max_line_length) sniff_base64 = binascii.b2a_base64(sniff) # This is a little unfair to qp; it includes lineseps, base64 doesn't. if len(sniff_qp) > len(sniff_base64): cte = 'base64' else: cte = 'quoted-printable' if len(lines) <= 10: return cte, sniff_qp if cte == '7bit': data = normal_body(lines).decode('ascii') elif cte == '8bit': data = normal_body(lines).decode('ascii', 'surrogateescape') elif cte == 'quoted-printable': data = quoprimime.body_encode(normal_body(lines).decode('latin-1'), policy.max_line_length) elif cte == 'base64': data = _encode_base64(embedded_body(lines), policy.max_line_length) else: raise ValueError("Unknown content transfer encoding {}".format(cte)) return cte, data def set_text_content(msg, string, subtype="plain", charset='utf-8', cte=None, disposition=None, filename=None, cid=None, params=None, headers=None): _prepare_set(msg, 'text', subtype, headers) cte, payload = _encode_text(string, charset, cte, msg.policy) msg.set_payload(payload) msg.set_param('charset', email.charset.ALIASES.get(charset, charset), replace=True) msg['Content-Transfer-Encoding'] = cte _finalize_set(msg, disposition, filename, cid, params) raw_data_manager.add_set_handler(str, set_text_content) def set_message_content(msg, message, subtype="rfc822", cte=None, disposition=None, filename=None, cid=None, params=None, headers=None): if subtype == 'partial': raise ValueError("message/partial is not supported for Message objects") if subtype == 'rfc822': if cte not in (None, '7bit', '8bit', 'binary'): # http://tools.ietf.org/html/rfc2046#section-5.2.1 mandate. raise ValueError( "message/rfc822 parts do not support cte={}".format(cte)) # 8bit will get coerced on serialization if policy.cte_type='7bit'. We # may end up claiming 8bit when it isn't needed, but the only negative # result of that should be a gateway that needs to coerce to 7bit # having to look through the whole embedded message to discover whether # or not it actually has to do anything. cte = '8bit' if cte is None else cte elif subtype == 'external-body': if cte not in (None, '7bit'): # http://tools.ietf.org/html/rfc2046#section-5.2.3 mandate. raise ValueError( "message/external-body parts do not support cte={}".format(cte)) cte = '7bit' elif cte is None: # http://tools.ietf.org/html/rfc2046#section-5.2.4 says all future # subtypes should be restricted to 7bit, so assume that. cte = '7bit' _prepare_set(msg, 'message', subtype, headers) msg.set_payload([message]) msg['Content-Transfer-Encoding'] = cte _finalize_set(msg, disposition, filename, cid, params) raw_data_manager.add_set_handler(email.message.Message, set_message_content) def set_bytes_content(msg, data, maintype, subtype, cte='base64', disposition=None, filename=None, cid=None, params=None, headers=None): _prepare_set(msg, maintype, subtype, headers) if cte == 'base64': data = _encode_base64(data, max_line_length=msg.policy.max_line_length) elif cte == 'quoted-printable': # XXX: quoprimime.body_encode won't encode newline characters in data, # so we can't use it. This means max_line_length is ignored. Another # bug to fix later. (Note: encoders.quopri is broken on line ends.) data = binascii.b2a_qp(data, istext=False, header=False, quotetabs=True) data = data.decode('ascii') elif cte == '7bit': # Make sure it really is only ASCII. The early warning here seems # worth the overhead...if you care write your own content manager :). data.encode('ascii') elif cte in ('8bit', 'binary'): data = data.decode('ascii', 'surrogateescape') msg.set_payload(data) msg['Content-Transfer-Encoding'] = cte _finalize_set(msg, disposition, filename, cid, params) for typ in (bytes, bytearray, memoryview): raw_data_manager.add_set_handler(typ, set_bytes_content)