1 """This will be the home for the policy that hooks in the new
2 code that adds all the email6 features.
3 """
4
5 import re
6 import sys
7 from email._policybase import Policy, Compat32, compat32, _extend_docstrings
8 from email.utils import _has_surrogates
9 from email.headerregistry import HeaderRegistry as HeaderRegistry
10 from email.contentmanager import raw_data_manager
11 from email.message import EmailMessage
12
13 __all__ = [
14 'Compat32',
15 'compat32',
16 'Policy',
17 'EmailPolicy',
18 'default',
19 'strict',
20 'SMTP',
21 'HTTP',
22 ]
23
24 linesep_splitter = re.compile(r'\n|\r')
25
26 @_extend_docstrings
27 class ESC[4;38;5;81mEmailPolicy(ESC[4;38;5;149mPolicy):
28
29 """+
30 PROVISIONAL
31
32 The API extensions enabled by this policy are currently provisional.
33 Refer to the documentation for details.
34
35 This policy adds new header parsing and folding algorithms. Instead of
36 simple strings, headers are custom objects with custom attributes
37 depending on the type of the field. The folding algorithm fully
38 implements RFCs 2047 and 5322.
39
40 In addition to the settable attributes listed above that apply to
41 all Policies, this policy adds the following additional attributes:
42
43 utf8 -- if False (the default) message headers will be
44 serialized as ASCII, using encoded words to encode
45 any non-ASCII characters in the source strings. If
46 True, the message headers will be serialized using
47 utf8 and will not contain encoded words (see RFC
48 6532 for more on this serialization format).
49
50 refold_source -- if the value for a header in the Message object
51 came from the parsing of some source, this attribute
52 indicates whether or not a generator should refold
53 that value when transforming the message back into
54 stream form. The possible values are:
55
56 none -- all source values use original folding
57 long -- source values that have any line that is
58 longer than max_line_length will be
59 refolded
60 all -- all values are refolded.
61
62 The default is 'long'.
63
64 header_factory -- a callable that takes two arguments, 'name' and
65 'value', where 'name' is a header field name and
66 'value' is an unfolded header field value, and
67 returns a string-like object that represents that
68 header. A default header_factory is provided that
69 understands some of the RFC5322 header field types.
70 (Currently address fields and date fields have
71 special treatment, while all other fields are
72 treated as unstructured. This list will be
73 completed before the extension is marked stable.)
74
75 content_manager -- an object with at least two methods: get_content
76 and set_content. When the get_content or
77 set_content method of a Message object is called,
78 it calls the corresponding method of this object,
79 passing it the message object as its first argument,
80 and any arguments or keywords that were passed to
81 it as additional arguments. The default
82 content_manager is
83 :data:`~email.contentmanager.raw_data_manager`.
84
85 """
86
87 message_factory = EmailMessage
88 utf8 = False
89 refold_source = 'long'
90 header_factory = HeaderRegistry()
91 content_manager = raw_data_manager
92
93 def __init__(self, **kw):
94 # Ensure that each new instance gets a unique header factory
95 # (as opposed to clones, which share the factory).
96 if 'header_factory' not in kw:
97 object.__setattr__(self, 'header_factory', HeaderRegistry())
98 super().__init__(**kw)
99
100 def header_max_count(self, name):
101 """+
102 The implementation for this class returns the max_count attribute from
103 the specialized header class that would be used to construct a header
104 of type 'name'.
105 """
106 return self.header_factory[name].max_count
107
108 # The logic of the next three methods is chosen such that it is possible to
109 # switch a Message object between a Compat32 policy and a policy derived
110 # from this class and have the results stay consistent. This allows a
111 # Message object constructed with this policy to be passed to a library
112 # that only handles Compat32 objects, or to receive such an object and
113 # convert it to use the newer style by just changing its policy. It is
114 # also chosen because it postpones the relatively expensive full rfc5322
115 # parse until as late as possible when parsing from source, since in many
116 # applications only a few headers will actually be inspected.
117
118 def header_source_parse(self, sourcelines):
119 """+
120 The name is parsed as everything up to the ':' and returned unmodified.
121 The value is determined by stripping leading whitespace off the
122 remainder of the first line, joining all subsequent lines together, and
123 stripping any trailing carriage return or linefeed characters. (This
124 is the same as Compat32).
125
126 """
127 name, value = sourcelines[0].split(':', 1)
128 value = value.lstrip(' \t') + ''.join(sourcelines[1:])
129 return (name, value.rstrip('\r\n'))
130
131 def header_store_parse(self, name, value):
132 """+
133 The name is returned unchanged. If the input value has a 'name'
134 attribute and it matches the name ignoring case, the value is returned
135 unchanged. Otherwise the name and value are passed to header_factory
136 method, and the resulting custom header object is returned as the
137 value. In this case a ValueError is raised if the input value contains
138 CR or LF characters.
139
140 """
141 if hasattr(value, 'name') and value.name.lower() == name.lower():
142 return (name, value)
143 if isinstance(value, str) and len(value.splitlines())>1:
144 # XXX this error message isn't quite right when we use splitlines
145 # (see issue 22233), but I'm not sure what should happen here.
146 raise ValueError("Header values may not contain linefeed "
147 "or carriage return characters")
148 return (name, self.header_factory(name, value))
149
150 def header_fetch_parse(self, name, value):
151 """+
152 If the value has a 'name' attribute, it is returned to unmodified.
153 Otherwise the name and the value with any linesep characters removed
154 are passed to the header_factory method, and the resulting custom
155 header object is returned. Any surrogateescaped bytes get turned
156 into the unicode unknown-character glyph.
157
158 """
159 if hasattr(value, 'name'):
160 return value
161 # We can't use splitlines here because it splits on more than \r and \n.
162 value = ''.join(linesep_splitter.split(value))
163 return self.header_factory(name, value)
164
165 def fold(self, name, value):
166 """+
167 Header folding is controlled by the refold_source policy setting. A
168 value is considered to be a 'source value' if and only if it does not
169 have a 'name' attribute (having a 'name' attribute means it is a header
170 object of some sort). If a source value needs to be refolded according
171 to the policy, it is converted into a custom header object by passing
172 the name and the value with any linesep characters removed to the
173 header_factory method. Folding of a custom header object is done by
174 calling its fold method with the current policy.
175
176 Source values are split into lines using splitlines. If the value is
177 not to be refolded, the lines are rejoined using the linesep from the
178 policy and returned. The exception is lines containing non-ascii
179 binary data. In that case the value is refolded regardless of the
180 refold_source setting, which causes the binary data to be CTE encoded
181 using the unknown-8bit charset.
182
183 """
184 return self._fold(name, value, refold_binary=True)
185
186 def fold_binary(self, name, value):
187 """+
188 The same as fold if cte_type is 7bit, except that the returned value is
189 bytes.
190
191 If cte_type is 8bit, non-ASCII binary data is converted back into
192 bytes. Headers with binary data are not refolded, regardless of the
193 refold_header setting, since there is no way to know whether the binary
194 data consists of single byte characters or multibyte characters.
195
196 If utf8 is true, headers are encoded to utf8, otherwise to ascii with
197 non-ASCII unicode rendered as encoded words.
198
199 """
200 folded = self._fold(name, value, refold_binary=self.cte_type=='7bit')
201 charset = 'utf8' if self.utf8 else 'ascii'
202 return folded.encode(charset, 'surrogateescape')
203
204 def _fold(self, name, value, refold_binary=False):
205 if hasattr(value, 'name'):
206 return value.fold(policy=self)
207 maxlen = self.max_line_length if self.max_line_length else sys.maxsize
208 lines = value.splitlines()
209 refold = (self.refold_source == 'all' or
210 self.refold_source == 'long' and
211 (lines and len(lines[0])+len(name)+2 > maxlen or
212 any(len(x) > maxlen for x in lines[1:])))
213 if refold or refold_binary and _has_surrogates(value):
214 return self.header_factory(name, ''.join(lines)).fold(policy=self)
215 return name + ': ' + self.linesep.join(lines) + self.linesep
216
217
218 default = EmailPolicy()
219 # Make the default policy use the class default header_factory
220 del default.header_factory
221 strict = default.clone(raise_on_defect=True)
222 SMTP = default.clone(linesep='\r\n')
223 HTTP = default.clone(linesep='\r\n', max_line_length=None)
224 SMTPUTF8 = SMTP.clone(utf8=True)