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Diffstat (limited to 'Lib/email/_headerregistry.py')
| -rw-r--r-- | Lib/email/_headerregistry.py | 456 |
1 files changed, 456 insertions, 0 deletions
diff --git a/Lib/email/_headerregistry.py b/Lib/email/_headerregistry.py new file mode 100644 index 0000000..6588546 --- /dev/null +++ b/Lib/email/_headerregistry.py @@ -0,0 +1,456 @@ +"""Representing and manipulating email headers via custom objects. + +This module provides an implementation of the HeaderRegistry API. +The implementation is designed to flexibly follow RFC5322 rules. + +Eventually HeaderRegistry will be a public API, but it isn't yet, +and will probably change some before that happens. + +""" + +from email import utils +from email import errors +from email import _header_value_parser as parser + +class Address: + + def __init__(self, display_name='', username='', domain='', addr_spec=None): + """Create an object represeting a full email address. + + An address can have a 'display_name', a 'username', and a 'domain'. In + addition to specifying the username and domain separately, they may be + specified together by using the addr_spec keyword *instead of* the + username and domain keywords. If an addr_spec string is specified it + must be properly quoted according to RFC 5322 rules; an error will be + raised if it is not. + + An Address object has display_name, username, domain, and addr_spec + attributes, all of which are read-only. The addr_spec and the string + value of the object are both quoted according to RFC5322 rules, but + without any Content Transfer Encoding. + + """ + # This clause with its potential 'raise' may only happen when an + # application program creates an Address object using an addr_spec + # keyword. The email library code itself must always supply username + # and domain. + if addr_spec is not None: + if username or domain: + raise TypeError("addrspec specified when username and/or " + "domain also specified") + a_s, rest = parser.get_addr_spec(addr_spec) + if rest: + raise ValueError("Invalid addr_spec; only '{}' " + "could be parsed from '{}'".format( + a_s, addr_spec)) + if a_s.all_defects: + raise a_s.all_defects[0] + username = a_s.local_part + domain = a_s.domain + self._display_name = display_name + self._username = username + self._domain = domain + + @property + def display_name(self): + return self._display_name + + @property + def username(self): + return self._username + + @property + def domain(self): + return self._domain + + @property + def addr_spec(self): + """The addr_spec (username@domain) portion of the address, quoted + according to RFC 5322 rules, but with no Content Transfer Encoding. + """ + nameset = set(self.username) + if len(nameset) > len(nameset-parser.DOT_ATOM_ENDS): + lp = parser.quote_string(self.username) + else: + lp = self.username + if self.domain: + return lp + '@' + self.domain + if not lp: + return '<>' + return lp + + def __repr__(self): + return "Address(display_name={!r}, username={!r}, domain={!r})".format( + self.display_name, self.username, self.domain) + + def __str__(self): + nameset = set(self.display_name) + if len(nameset) > len(nameset-parser.SPECIALS): + disp = parser.quote_string(self.display_name) + else: + disp = self.display_name + if disp: + addr_spec = '' if self.addr_spec=='<>' else self.addr_spec + return "{} <{}>".format(disp, addr_spec) + return self.addr_spec + + def __eq__(self, other): + if type(other) != type(self): + return False + return (self.display_name == other.display_name and + self.username == other.username and + self.domain == other.domain) + + +class Group: + + def __init__(self, display_name=None, addresses=None): + """Create an object representing an address group. + + An address group consists of a display_name followed by colon and an + list of addresses (see Address) terminated by a semi-colon. The Group + is created by specifying a display_name and a possibly empty list of + Address objects. A Group can also be used to represent a single + address that is not in a group, which is convenient when manipulating + lists that are a combination of Groups and individual Addresses. In + this case the display_name should be set to None. In particular, the + string representation of a Group whose display_name is None is the same + as the Address object, if there is one and only one Address object in + the addresses list. + + """ + self._display_name = display_name + self._addresses = tuple(addresses) if addresses else tuple() + + @property + def display_name(self): + return self._display_name + + @property + def addresses(self): + return self._addresses + + def __repr__(self): + return "Group(display_name={!r}, addresses={!r}".format( + self.display_name, self.addresses) + + def __str__(self): + if self.display_name is None and len(self.addresses)==1: + return str(self.addresses[0]) + disp = self.display_name + if disp is not None: + nameset = set(disp) + if len(nameset) > len(nameset-parser.SPECIALS): + disp = parser.quote_string(disp) + adrstr = ", ".join(str(x) for x in self.addresses) + adrstr = ' ' + adrstr if adrstr else adrstr + return "{}:{};".format(disp, adrstr) + + def __eq__(self, other): + if type(other) != type(self): + return False + return (self.display_name == other.display_name and + self.addresses == other.addresses) + + +# Header Classes # + +class BaseHeader(str): + + """Base class for message headers. + + Implements generic behavior and provides tools for subclasses. + + A subclass must define a classmethod named 'parse' that takes an unfolded + value string and a dictionary as its arguments. The dictionary will + contain one key, 'defects', initialized to an empty list. After the call + the dictionary must contain two additional keys: parse_tree, set to the + parse tree obtained from parsing the header, and 'decoded', set to the + string value of the idealized representation of the data from the value. + (That is, encoded words are decoded, and values that have canonical + representations are so represented.) + + The defects key is intended to collect parsing defects, which the message + parser will subsequently dispose of as appropriate. The parser should not, + insofar as practical, raise any errors. Defects should be added to the + list instead. The standard header parsers register defects for RFC + compliance issues, for obsolete RFC syntax, and for unrecoverable parsing + errors. + + The parse method may add additional keys to the dictionary. In this case + the subclass must define an 'init' method, which will be passed the + dictionary as its keyword arguments. The method should use (usually by + setting them as the value of similarly named attributes) and remove all the + extra keys added by its parse method, and then use super to call its parent + class with the remaining arguments and keywords. + + The subclass should also make sure that a 'max_count' attribute is defined + that is either None or 1. XXX: need to better define this API. + + """ + + def __new__(cls, name, value): + kwds = {'defects': []} + cls.parse(value, kwds) + if utils._has_surrogates(kwds['decoded']): + kwds['decoded'] = utils._sanitize(kwds['decoded']) + self = str.__new__(cls, kwds['decoded']) + del kwds['decoded'] + self.init(name, **kwds) + return self + + def init(self, name, *, parse_tree, defects): + self._name = name + self._parse_tree = parse_tree + self._defects = defects + + @property + def name(self): + return self._name + + @property + def defects(self): + return tuple(self._defects) + + def __reduce__(self): + return ( + _reconstruct_header, + ( + self.__class__.__name__, + self.__class__.__bases__, + str(self), + ), + self.__dict__) + + @classmethod + def _reconstruct(cls, value): + return str.__new__(cls, value) + + def fold(self, *, policy): + """Fold header according to policy. + + The parsed representation of the header is folded according to + RFC5322 rules, as modified by the policy. If the parse tree + contains surrogateescaped bytes, the bytes are CTE encoded using + the charset 'unknown-8bit". + + Any non-ASCII characters in the parse tree are CTE encoded using + charset utf-8. XXX: make this a policy setting. + + The returned value is an ASCII-only string possibly containing linesep + characters, and ending with a linesep character. The string includes + the header name and the ': ' separator. + + """ + # At some point we need to only put fws here if it was in the source. + header = parser.Header([ + parser.HeaderLabel([ + parser.ValueTerminal(self.name, 'header-name'), + parser.ValueTerminal(':', 'header-sep')]), + parser.CFWSList([parser.WhiteSpaceTerminal(' ', 'fws')]), + self._parse_tree]) + return header.fold(policy=policy) + + +def _reconstruct_header(cls_name, bases, value): + return type(cls_name, bases, {})._reconstruct(value) + + +class UnstructuredHeader: + + max_count = None + value_parser = staticmethod(parser.get_unstructured) + + @classmethod + def parse(cls, value, kwds): + kwds['parse_tree'] = cls.value_parser(value) + kwds['decoded'] = str(kwds['parse_tree']) + + +class UniqueUnstructuredHeader(UnstructuredHeader): + + max_count = 1 + + +class DateHeader: + + """Header whose value consists of a single timestamp. + + Provides an additional attribute, datetime, which is either an aware + datetime using a timezone, or a naive datetime if the timezone + in the input string is -0000. Also accepts a datetime as input. + The 'value' attribute is the normalized form of the timestamp, + which means it is the output of format_datetime on the datetime. + """ + + max_count = None + + # This is used only for folding, not for creating 'decoded'. + value_parser = staticmethod(parser.get_unstructured) + + @classmethod + def parse(cls, value, kwds): + if not value: + kwds['defects'].append(errors.HeaderMissingRequiredValue()) + kwds['datetime'] = None + kwds['decoded'] = '' + kwds['parse_tree'] = parser.TokenList() + return + if isinstance(value, str): + value = utils.parsedate_to_datetime(value) + kwds['datetime'] = value + kwds['decoded'] = utils.format_datetime(kwds['datetime']) + kwds['parse_tree'] = cls.value_parser(kwds['decoded']) + + def init(self, *args, **kw): + self._datetime = kw.pop('datetime') + super().init(*args, **kw) + + @property + def datetime(self): + return self._datetime + + +class UniqueDateHeader(DateHeader): + + max_count = 1 + + +class AddressHeader: + + max_count = None + + @staticmethod + def value_parser(value): + address_list, value = parser.get_address_list(value) + assert not value, 'this should not happen' + return address_list + + @classmethod + def parse(cls, value, kwds): + if isinstance(value, str): + # We are translating here from the RFC language (address/mailbox) + # to our API language (group/address). + kwds['parse_tree'] = address_list = cls.value_parser(value) + groups = [] + for addr in address_list.addresses: + groups.append(Group(addr.display_name, + [Address(mb.display_name or '', + mb.local_part or '', + mb.domain or '') + for mb in addr.all_mailboxes])) + defects = list(address_list.all_defects) + else: + # Assume it is Address/Group stuff + if not hasattr(value, '__iter__'): + value = [value] + groups = [Group(None, [item]) if not hasattr(item, 'addresses') + else item + for item in value] + defects = [] + kwds['groups'] = groups + kwds['defects'] = defects + kwds['decoded'] = ', '.join([str(item) for item in groups]) + if 'parse_tree' not in kwds: + kwds['parse_tree'] = cls.value_parser(kwds['decoded']) + + def init(self, *args, **kw): + self._groups = tuple(kw.pop('groups')) + self._addresses = None + super().init(*args, **kw) + + @property + def groups(self): + return self._groups + + @property + def addresses(self): + if self._addresses is None: + self._addresses = tuple([address for group in self._groups + for address in group.addresses]) + return self._addresses + + +class UniqueAddressHeader(AddressHeader): + + max_count = 1 + + +class SingleAddressHeader(AddressHeader): + + @property + def address(self): + if len(self.addresses)!=1: + raise ValueError(("value of single address header {} is not " + "a single address").format(self.name)) + return self.addresses[0] + + +class UniqueSingleAddressHeader(SingleAddressHeader): + + max_count = 1 + + +# The header factory # + +_default_header_map = { + 'subject': UniqueUnstructuredHeader, + 'date': UniqueDateHeader, + 'resent-date': DateHeader, + 'orig-date': UniqueDateHeader, + 'sender': UniqueSingleAddressHeader, + 'resent-sender': SingleAddressHeader, + 'to': UniqueAddressHeader, + 'resent-to': AddressHeader, + 'cc': UniqueAddressHeader, + 'resent-cc': AddressHeader, + 'bcc': UniqueAddressHeader, + 'resent-bcc': AddressHeader, + 'from': UniqueAddressHeader, + 'resent-from': AddressHeader, + 'reply-to': UniqueAddressHeader, + } + +class HeaderRegistry: + + """A header_factory and header registry.""" + + def __init__(self, base_class=BaseHeader, default_class=UnstructuredHeader, + use_default_map=True): + """Create a header_factory that works with the Policy API. + + base_class is the class that will be the last class in the created + header class's __bases__ list. default_class is the class that will be + used if "name" (see __call__) does not appear in the registry. + use_default_map controls whether or not the default mapping of names to + specialized classes is copied in to the registry when the factory is + created. The default is True. + + """ + self.registry = {} + self.base_class = base_class + self.default_class = default_class + if use_default_map: + self.registry.update(_default_header_map) + + def map_to_type(self, name, cls): + """Register cls as the specialized class for handling "name" headers. + + """ + self.registry[name.lower()] = cls + + def __getitem__(self, name): + cls = self.registry.get(name.lower(), self.default_class) + return type('_'+cls.__name__, (cls, self.base_class), {}) + + def __call__(self, name, value): + """Create a header instance for header 'name' from 'value'. + + Creates a header instance by creating a specialized class for parsing + and representing the specified header by combining the factory + base_class with a specialized class from the registry or the + default_class, and passing the name and value to the constructed + class's constructor. + + """ + return self[name](name, value) |