| # 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'] |
| |
| import re |
| |
| from email import errors |
| from email import message |
| |
| 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): |
| # 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._lines.append(self._partial) |
| 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.""" |
| # Handle any previous leftovers |
| data, self._partial = self._partial + data, '' |
| # Crack into lines, but preserve the newlines on the end of each |
| parts = NLCRE_crack.split(data) |
| # The *ahem* interesting behaviour of re.split when supplied grouping |
| # parentheses is that the last element of the resulting list is the |
| # data after the final RE. In the case of a NL/CR terminated string, |
| # this is the empty string. |
| self._partial = parts.pop() |
| #GAN 29Mar09 bugs 1555570, 1721862 Confusion at 8K boundary ending with \r: |
| # is there a \n to follow later? |
| if not self._partial and parts and parts[-1].endswith('\r'): |
| self._partial = parts.pop(-2)+parts.pop() |
| # parts is a list of strings, alternating between the line contents |
| # and the eol character(s). Gather up a list of lines after |
| # re-attaching the newlines. |
| lines = [] |
| for i in range(len(parts) // 2): |
| lines.append(parts[i*2] + parts[i*2+1]) |
| self.pushlines(lines) |
| |
| def pushlines(self, lines): |
| # Reverse and insert at the front of the lines. |
| self._lines[:0] = lines[::-1] |
| |
| def is_closed(self): |
| return self._closed |
| |
| 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=message.Message): |
| """_factory is called with no arguments to create a new message obj""" |
| self._factory = _factory |
| 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(): |
| root.defects.append(errors.MultipartInvariantViolationDefect()) |
| return root |
| |
| def _new_message(self): |
| msg = self._factory() |
| 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): |
| 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. |
| self._cur.defects.append(errors.NoBoundaryInMultipartDefect()) |
| lines = [] |
| for line in self._input: |
| if line is NeedMoreData: |
| yield NeedMoreData |
| continue |
| lines.append(line) |
| self._cur.set_payload(EMPTYSTRING.join(lines)) |
| return |
| # 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 |
| 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'): |
| 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.get_payload() |
| if isinstance(payload, basestring): |
| mo = NLCRE_eol.search(payload) |
| if mo: |
| payload = payload[:-len(mo.group(0))] |
| self._last.set_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. |
| # Everything from here to the EOF is epilogue. |
| if capturing_preamble: |
| self._cur.defects.append(errors.StartBoundaryNotFoundDefect()) |
| 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 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._cur.defects.append(defect) |
| continue |
| lastvalue.append(line) |
| continue |
| if lastheader: |
| # XXX reconsider the joining of folded lines |
| lhdr = EMPTYSTRING.join(lastvalue)[:-1].rstrip('\r\n') |
| self._cur[lastheader] = lhdr |
| 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. |
| i = line.find(':') |
| if i < 0: |
| defect = errors.MalformedHeaderDefect(line) |
| self._cur.defects.append(defect) |
| continue |
| lastheader = line[:i] |
| lastvalue = [line[i+1:].lstrip()] |
| # Done with all the lines, so handle the last header. |
| if lastheader: |
| # XXX reconsider the joining of folded lines |
| self._cur[lastheader] = EMPTYSTRING.join(lastvalue).rstrip('\r\n') |
