summaryrefslogtreecommitdiffstats
path: root/Lib/email/feedparser.py
blob: 0c3b572684f432e1560f34ba31f0b5f5171177ca (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
# Copyright (C) 2004-2006 Python Software Foundation
# Authors: Baxter, Wouters and Warsaw
# Contact: email-sig@python.org

"""FeedParser - An email feed parser.

The feed parser implements an interface for incrementally parsing an email
message, line by line.  This has advantages for certain applications, such as
those reading email messages off a socket.

FeedParser.feed() is the primary interface for pushing new data into the
parser.  It returns when there's nothing more it can do with the available
data.  When you have no more data to push into the parser, call .close().
This completes the parsing and returns the root message object.

The other advantage of this parser is that it will never raise a parsing
exception.  Instead, when it finds something unexpected, it adds a 'defect' to
the current message.  Defects are just instances that live on the message
object's .defects attribute.
"""

__all__ = ['FeedParser', 'BytesFeedParser']

import re

from email import errors
from email import message
from email._policybase import compat32

NLCRE = re.compile('\r\n|\r|\n')
NLCRE_bol = re.compile('(\r\n|\r|\n)')
NLCRE_eol = re.compile('(\r\n|\r|\n)\Z')
NLCRE_crack = re.compile('(\r\n|\r|\n)')
# RFC 2822 $3.6.8 Optional fields.  ftext is %d33-57 / %d59-126, Any character
# except controls, SP, and ":".
headerRE = re.compile(r'^(From |[\041-\071\073-\176]{1,}:|[\t ])')
EMPTYSTRING = ''
NL = '\n'

NeedMoreData = object()



class BufferedSubFile(object):
    """A file-ish object that can have new data loaded into it.

    You can also push and pop line-matching predicates onto a stack.  When the
    current predicate matches the current line, a false EOF response
    (i.e. empty string) is returned instead.  This lets the parser adhere to a
    simple abstraction -- it parses until EOF closes the current message.
    """
    def __init__(self):
        # Chunks of the last partial line pushed into this object.
        self._partial = []
        # The list of full, pushed lines, in reverse order
        self._lines = []
        # The stack of false-EOF checking predicates.
        self._eofstack = []
        # A flag indicating whether the file has been closed or not.
        self._closed = False

    def push_eof_matcher(self, pred):
        self._eofstack.append(pred)

    def pop_eof_matcher(self):
        return self._eofstack.pop()

    def close(self):
        # Don't forget any trailing partial line.
        self.pushlines(''.join(self._partial).splitlines(True))
        self._partial = []
        self._closed = True

    def readline(self):
        if not self._lines:
            if self._closed:
                return ''
            return NeedMoreData
        # Pop the line off the stack and see if it matches the current
        # false-EOF predicate.
        line = self._lines.pop()
        # RFC 2046, section 5.1.2 requires us to recognize outer level
        # boundaries at any level of inner nesting.  Do this, but be sure it's
        # in the order of most to least nested.
        for ateof in self._eofstack[::-1]:
            if ateof(line):
                # We're at the false EOF.  But push the last line back first.
                self._lines.append(line)
                return ''
        return line

    def unreadline(self, line):
        # Let the consumer push a line back into the buffer.
        assert line is not NeedMoreData
        self._lines.append(line)

    def push(self, data):
        """Push some new data into this object."""
        # Crack into lines, but preserve the linesep characters on the end of each
        parts = data.splitlines(True)

        if not parts or not parts[0].endswith(('\n', '\r')):
            # No new complete lines, so just accumulate partials
            self._partial += parts
            return

        if self._partial:
            # If there are previous leftovers, complete them now
            self._partial.append(parts[0])
            parts[0:1] = ''.join(self._partial).splitlines(True)
            del self._partial[:]

        # If the last element of the list does not end in a newline, then treat
        # it as a partial line.  We only check for '\n' here because a line
        # ending with '\r' might be a line that was split in the middle of a
        # '\r\n' sequence (see bugs 1555570 and 1721862).
        if not parts[-1].endswith('\n'):
            self._partial = [parts.pop()]
        self.pushlines(parts)

    def pushlines(self, lines):
        # Reverse and insert at the front of the lines.
        self._lines[:0] = lines[::-1]

    def __iter__(self):
        return self

    def __next__(self):
        line = self.readline()
        if line == '':
            raise StopIteration
        return line



class FeedParser:
    """A feed-style parser of email."""

    def __init__(self, _factory=None, *, policy=compat32):
        """_factory is called with no arguments to create a new message obj

        The policy keyword specifies a policy object that controls a number of
        aspects of the parser's operation.  The default policy maintains
        backward compatibility.

        """
        self.policy = policy
        self._factory_kwds = lambda: {'policy': self.policy}
        if _factory is None:
            # What this should be:
            #self._factory = policy.default_message_factory
            # but, because we are post 3.4 feature freeze, fix with temp hack:
            if self.policy is compat32:
                self._factory = message.Message
            else:
                self._factory = message.EmailMessage
        else:
            self._factory = _factory
            try:
                _factory(policy=self.policy)
            except TypeError:
                # Assume this is an old-style factory
                self._factory_kwds = lambda: {}
        self._input = BufferedSubFile()
        self._msgstack = []
        self._parse = self._parsegen().__next__
        self._cur = None
        self._last = None
        self._headersonly = False

    # Non-public interface for supporting Parser's headersonly flag
    def _set_headersonly(self):
        self._headersonly = True

    def feed(self, data):
        """Push more data into the parser."""
        self._input.push(data)
        self._call_parse()

    def _call_parse(self):
        try:
            self._parse()
        except StopIteration:
            pass

    def close(self):
        """Parse all remaining data and return the root message object."""
        self._input.close()
        self._call_parse()
        root = self._pop_message()
        assert not self._msgstack
        # Look for final set of defects
        if root.get_content_maintype() == 'multipart' \
               and not root.is_multipart():
            defect = errors.MultipartInvariantViolationDefect()
            self.policy.handle_defect(root, defect)
        return root

    def _new_message(self):
        msg = self._factory(**self._factory_kwds())
        if self._cur and self._cur.get_content_type() == 'multipart/digest':
            msg.set_default_type('message/rfc822')
        if self._msgstack:
            self._msgstack[-1].attach(msg)
        self._msgstack.append(msg)
        self._cur = msg
        self._last = msg

    def _pop_message(self):
        retval = self._msgstack.pop()
        if self._msgstack:
            self._cur = self._msgstack[-1]
        else:
            self._cur = None
        return retval

    def _parsegen(self):
        # Create a new message and start by parsing headers.
        self._new_message()
        headers = []
        # Collect the headers, searching for a line that doesn't match the RFC
        # 2822 header or continuation pattern (including an empty line).
        for line in self._input:
            if line is NeedMoreData:
                yield NeedMoreData
                continue
            if not headerRE.match(line):
                # If we saw the RFC defined header/body separator
                # (i.e. newline), just throw it away. Otherwise the line is
                # part of the body so push it back.
                if not NLCRE.match(line):
                    defect = errors.MissingHeaderBodySeparatorDefect()
                    self.policy.handle_defect(self._cur, defect)
                    self._input.unreadline(line)
                break
            headers.append(line)
        # Done with the headers, so parse them and figure out what we're
        # supposed to see in the body of the message.
        self._parse_headers(headers)
        # Headers-only parsing is a backwards compatibility hack, which was
        # necessary in the older parser, which could raise errors.  All
        # remaining lines in the input are thrown into the message body.
        if self._headersonly:
            lines = []
            while True:
                line = self._input.readline()
                if line is NeedMoreData:
                    yield NeedMoreData
                    continue
                if line == '':
                    break
                lines.append(line)
            self._cur.set_payload(EMPTYSTRING.join(lines))
            return
        if self._cur.get_content_type() == 'message/delivery-status':
            # message/delivery-status contains blocks of headers separated by
            # a blank line.  We'll represent each header block as a separate
            # nested message object, but the processing is a bit different
            # than standard message/* types because there is no body for the
            # nested messages.  A blank line separates the subparts.
            while True:
                self._input.push_eof_matcher(NLCRE.match)
                for retval in self._parsegen():
                    if retval is NeedMoreData:
                        yield NeedMoreData
                        continue
                    break
                msg = self._pop_message()
                # We need to pop the EOF matcher in order to tell if we're at
                # the end of the current file, not the end of the last block
                # of message headers.
                self._input.pop_eof_matcher()
                # The input stream must be sitting at the newline or at the
                # EOF.  We want to see if we're at the end of this subpart, so
                # first consume the blank line, then test the next line to see
                # if we're at this subpart's EOF.
                while True:
                    line = self._input.readline()
                    if line is NeedMoreData:
                        yield NeedMoreData
                        continue
                    break
                while True:
                    line = self._input.readline()
                    if line is NeedMoreData:
                        yield NeedMoreData
                        continue
                    break
                if line == '':
                    break
                # Not at EOF so this is a line we're going to need.
                self._input.unreadline(line)
            return
        if self._cur.get_content_maintype() == 'message':
            # The message claims to be a message/* type, then what follows is
            # another RFC 2822 message.
            for retval in self._parsegen():
                if retval is NeedMoreData:
                    yield NeedMoreData
                    continue
                break
            self._pop_message()
            return
        if self._cur.get_content_maintype() == 'multipart':
            boundary = self._cur.get_boundary()
            if boundary is None:
                # The message /claims/ to be a multipart but it has not
                # defined a boundary.  That's a problem which we'll handle by
                # reading everything until the EOF and marking the message as
                # defective.
                defect = errors.NoBoundaryInMultipartDefect()
                self.policy.handle_defect(self._cur, defect)
                lines = []
                for line in self._input:
                    if line is NeedMoreData:
                        yield NeedMoreData
                        continue
                    lines.append(line)
                self._cur.set_payload(EMPTYSTRING.join(lines))
                return
            # Make sure a valid content type was specified per RFC 2045:6.4.
            if (self._cur.get('content-transfer-encoding', '8bit').lower()
                    not in ('7bit', '8bit', 'binary')):
                defect = errors.InvalidMultipartContentTransferEncodingDefect()
                self.policy.handle_defect(self._cur, defect)
            # Create a line match predicate which matches the inter-part
            # boundary as well as the end-of-multipart boundary.  Don't push
            # this onto the input stream until we've scanned past the
            # preamble.
            separator = '--' + boundary
            boundaryre = re.compile(
                '(?P<sep>' + re.escape(separator) +
                r')(?P<end>--)?(?P<ws>[ \t]*)(?P<linesep>\r\n|\r|\n)?$')
            capturing_preamble = True
            preamble = []
            linesep = False
            close_boundary_seen = False
            while True:
                line = self._input.readline()
                if line is NeedMoreData:
                    yield NeedMoreData
                    continue
                if line == '':
                    break
                mo = boundaryre.match(line)
                if mo:
                    # If we're looking at the end boundary, we're done with
                    # this multipart.  If there was a newline at the end of
                    # the closing boundary, then we need to initialize the
                    # epilogue with the empty string (see below).
                    if mo.group('end'):
                        close_boundary_seen = True
                        linesep = mo.group('linesep')
                        break
                    # We saw an inter-part boundary.  Were we in the preamble?
                    if capturing_preamble:
                        if preamble:
                            # According to RFC 2046, the last newline belongs
                            # to the boundary.
                            lastline = preamble[-1]
                            eolmo = NLCRE_eol.search(lastline)
                            if eolmo:
                                preamble[-1] = lastline[:-len(eolmo.group(0))]
                            self._cur.preamble = EMPTYSTRING.join(preamble)
                        capturing_preamble = False
                        self._input.unreadline(line)
                        continue
                    # We saw a boundary separating two parts.  Consume any
                    # multiple boundary lines that may be following.  Our
                    # interpretation of RFC 2046 BNF grammar does not produce
                    # body parts within such double boundaries.
                    while True:
                        line = self._input.readline()
                        if line is NeedMoreData:
                            yield NeedMoreData
                            continue
                        mo = boundaryre.match(line)
                        if not mo:
                            self._input.unreadline(line)
                            break
                    # Recurse to parse this subpart; the input stream points
                    # at the subpart's first line.
                    self._input.push_eof_matcher(boundaryre.match)
                    for retval in self._parsegen():
                        if retval is NeedMoreData:
                            yield NeedMoreData
                            continue
                        break
                    # Because of RFC 2046, the newline preceding the boundary
                    # separator actually belongs to the boundary, not the
                    # previous subpart's payload (or epilogue if the previous
                    # part is a multipart).
                    if self._last.get_content_maintype() == 'multipart':
                        epilogue = self._last.epilogue
                        if epilogue == '':
                            self._last.epilogue = None
                        elif epilogue is not None:
                            mo = NLCRE_eol.search(epilogue)
                            if mo:
                                end = len(mo.group(0))
                                self._last.epilogue = epilogue[:-end]
                    else:
                        payload = self._last._payload
                        if isinstance(payload, str):
                            mo = NLCRE_eol.search(payload)
                            if mo:
                                payload = payload[:-len(mo.group(0))]
                                self._last._payload = payload
                    self._input.pop_eof_matcher()
                    self._pop_message()
                    # Set the multipart up for newline cleansing, which will
                    # happen if we're in a nested multipart.
                    self._last = self._cur
                else:
                    # I think we must be in the preamble
                    assert capturing_preamble
                    preamble.append(line)
            # We've seen either the EOF or the end boundary.  If we're still
            # capturing the preamble, we never saw the start boundary.  Note
            # that as a defect and store the captured text as the payload.
            if capturing_preamble:
                defect = errors.StartBoundaryNotFoundDefect()
                self.policy.handle_defect(self._cur, defect)
                self._cur.set_payload(EMPTYSTRING.join(preamble))
                epilogue = []
                for line in self._input:
                    if line is NeedMoreData:
                        yield NeedMoreData
                        continue
                self._cur.epilogue = EMPTYSTRING.join(epilogue)
                return
            # If we're not processing the preamble, then we might have seen
            # EOF without seeing that end boundary...that is also a defect.
            if not close_boundary_seen:
                defect = errors.CloseBoundaryNotFoundDefect()
                self.policy.handle_defect(self._cur, defect)
                return
            # Everything from here to the EOF is epilogue.  If the end boundary
            # ended in a newline, we'll need to make sure the epilogue isn't
            # None
            if linesep:
                epilogue = ['']
            else:
                epilogue = []
            for line in self._input:
                if line is NeedMoreData:
                    yield NeedMoreData
                    continue
                epilogue.append(line)
            # Any CRLF at the front of the epilogue is not technically part of
            # the epilogue.  Also, watch out for an empty string epilogue,
            # which means a single newline.
            if epilogue:
                firstline = epilogue[0]
                bolmo = NLCRE_bol.match(firstline)
                if bolmo:
                    epilogue[0] = firstline[len(bolmo.group(0)):]
            self._cur.epilogue = EMPTYSTRING.join(epilogue)
            return
        # Otherwise, it's some non-multipart type, so the entire rest of the
        # file contents becomes the payload.
        lines = []
        for line in self._input:
            if line is NeedMoreData:
                yield NeedMoreData
                continue
            lines.append(line)
        self._cur.set_payload(EMPTYSTRING.join(lines))

    def _parse_headers(self, lines):
        # Passed a list of lines that make up the headers for the current msg
        lastheader = ''
        lastvalue = []
        for lineno, line in enumerate(lines):
            # Check for continuation
            if line[0] in ' \t':
                if not lastheader:
                    # The first line of the headers was a continuation.  This
                    # is illegal, so let's note the defect, store the illegal
                    # line, and ignore it for purposes of headers.
                    defect = errors.FirstHeaderLineIsContinuationDefect(line)
                    self.policy.handle_defect(self._cur, defect)
                    continue
                lastvalue.append(line)
                continue
            if lastheader:
                self._cur.set_raw(*self.policy.header_source_parse(lastvalue))
                lastheader, lastvalue = '', []
            # Check for envelope header, i.e. unix-from
            if line.startswith('From '):
                if lineno == 0:
                    # Strip off the trailing newline
                    mo = NLCRE_eol.search(line)
                    if mo:
                        line = line[:-len(mo.group(0))]
                    self._cur.set_unixfrom(line)
                    continue
                elif lineno == len(lines) - 1:
                    # Something looking like a unix-from at the end - it's
                    # probably the first line of the body, so push back the
                    # line and stop.
                    self._input.unreadline(line)
                    return
                else:
                    # Weirdly placed unix-from line.  Note this as a defect
                    # and ignore it.
                    defect = errors.MisplacedEnvelopeHeaderDefect(line)
                    self._cur.defects.append(defect)
                    continue
            # Split the line on the colon separating field name from value.
            # There will always be a colon, because if there wasn't the part of
            # the parser that calls us would have started parsing the body.
            i = line.find(':')
            assert i>0, "_parse_headers fed line with no : and no leading WS"
            lastheader = line[:i]
            lastvalue = [line]
        # Done with all the lines, so handle the last header.
        if lastheader:
            self._cur.set_raw(*self.policy.header_source_parse(lastvalue))


class BytesFeedParser(FeedParser):
    """Like FeedParser, but feed accepts bytes."""

    def feed(self, data):
        super().feed(data.decode('ascii', 'surrogateescape'))