276 lines
12 KiB
Python
276 lines
12 KiB
Python
# Copyright (C) 2001,2002 Python Software Foundation
|
||
# Author: barry@zope.com (Barry Warsaw)
|
||
|
||
"""A parser of RFC 2822 and MIME email messages.
|
||
"""
|
||
|
||
import re
|
||
from cStringIO import StringIO
|
||
from types import ListType
|
||
|
||
from email import Errors
|
||
from email import Message
|
||
|
||
EMPTYSTRING = ''
|
||
NL = '\n'
|
||
|
||
try:
|
||
True, False
|
||
except NameError:
|
||
True = 1
|
||
False = 0
|
||
|
||
nlcre = re.compile('\r\n|\r|\n')
|
||
|
||
|
||
|
||
class Parser:
|
||
def __init__(self, _class=Message.Message, strict=False):
|
||
"""Parser of RFC 2822 and MIME email messages.
|
||
|
||
Creates an in-memory object tree representing the email message, which
|
||
can then be manipulated and turned over to a Generator to return the
|
||
textual representation of the message.
|
||
|
||
The string must be formatted as a block of RFC 2822 headers and header
|
||
continuation lines, optionally preceeded by a `Unix-from' header. The
|
||
header block is terminated either by the end of the string or by a
|
||
blank line.
|
||
|
||
_class is the class to instantiate for new message objects when they
|
||
must be created. This class must have a constructor that can take
|
||
zero arguments. Default is Message.Message.
|
||
|
||
Optional strict tells the parser to be strictly RFC compliant or to be
|
||
more forgiving in parsing of ill-formatted MIME documents. When
|
||
non-strict mode is used, the parser will try to make up for missing or
|
||
erroneous boundaries and other peculiarities seen in the wild.
|
||
Default is non-strict parsing.
|
||
"""
|
||
self._class = _class
|
||
self._strict = strict
|
||
|
||
def parse(self, fp, headersonly=False):
|
||
"""Create a message structure from the data in a file.
|
||
|
||
Reads all the data from the file and returns the root of the message
|
||
structure. Optional headersonly is a flag specifying whether to stop
|
||
parsing after reading the headers or not. The default is False,
|
||
meaning it parses the entire contents of the file.
|
||
"""
|
||
root = self._class()
|
||
self._parseheaders(root, fp)
|
||
if not headersonly:
|
||
self._parsebody(root, fp)
|
||
return root
|
||
|
||
def parsestr(self, text, headersonly=False):
|
||
"""Create a message structure from a string.
|
||
|
||
Returns the root of the message structure. Optional headersonly is a
|
||
flag specifying whether to stop parsing after reading the headers or
|
||
not. The default is False, meaning it parses the entire contents of
|
||
the file.
|
||
"""
|
||
return self.parse(StringIO(text), headersonly=headersonly)
|
||
|
||
def _parseheaders(self, container, fp):
|
||
# Parse the headers, returning a list of header/value pairs. None as
|
||
# the header means the Unix-From header.
|
||
lastheader = ''
|
||
lastvalue = []
|
||
lineno = 0
|
||
while True:
|
||
# Don't strip the line before we test for the end condition,
|
||
# because whitespace-only header lines are RFC compliant
|
||
# continuation lines.
|
||
line = fp.readline()
|
||
if not line:
|
||
break
|
||
line = line.splitlines()[0]
|
||
if not line:
|
||
break
|
||
# Ignore the trailing newline
|
||
lineno += 1
|
||
# Check for initial Unix From_ line
|
||
if line.startswith('From '):
|
||
if lineno == 1:
|
||
container.set_unixfrom(line)
|
||
continue
|
||
elif self._strict:
|
||
raise Errors.HeaderParseError(
|
||
'Unix-from in headers after first rfc822 header')
|
||
else:
|
||
# ignore the wierdly placed From_ line
|
||
# XXX: maybe set unixfrom anyway? or only if not already?
|
||
continue
|
||
# Header continuation line
|
||
if line[0] in ' \t':
|
||
if not lastheader:
|
||
raise Errors.HeaderParseError(
|
||
'Continuation line seen before first header')
|
||
lastvalue.append(line)
|
||
continue
|
||
# Normal, non-continuation header. BAW: this should check to make
|
||
# sure it's a legal header, e.g. doesn't contain spaces. Also, we
|
||
# should expose the header matching algorithm in the API, and
|
||
# allow for a non-strict parsing mode (that ignores the line
|
||
# instead of raising the exception).
|
||
i = line.find(':')
|
||
if i < 0:
|
||
if self._strict:
|
||
raise Errors.HeaderParseError(
|
||
"Not a header, not a continuation: ``%s''"%line)
|
||
elif lineno == 1 and line.startswith('--'):
|
||
# allow through duplicate boundary tags.
|
||
continue
|
||
else:
|
||
raise Errors.HeaderParseError(
|
||
"Not a header, not a continuation: ``%s''"%line)
|
||
if lastheader:
|
||
container[lastheader] = NL.join(lastvalue)
|
||
lastheader = line[:i]
|
||
lastvalue = [line[i+1:].lstrip()]
|
||
# Make sure we retain the last header
|
||
if lastheader:
|
||
container[lastheader] = NL.join(lastvalue)
|
||
|
||
def _parsebody(self, container, fp):
|
||
# Parse the body, but first split the payload on the content-type
|
||
# boundary if present.
|
||
boundary = container.get_boundary()
|
||
isdigest = (container.get_content_type() == 'multipart/digest')
|
||
# If there's a boundary, split the payload text into its constituent
|
||
# parts and parse each separately. Otherwise, just parse the rest of
|
||
# the body as a single message. Note: any exceptions raised in the
|
||
# recursive parse need to have their line numbers coerced.
|
||
if boundary:
|
||
preamble = epilogue = None
|
||
# Split into subparts. The first boundary we're looking for won't
|
||
# always have a leading newline since we're at the start of the
|
||
# body text, and there's not always a preamble before the first
|
||
# boundary.
|
||
separator = '--' + boundary
|
||
payload = fp.read()
|
||
# We use an RE here because boundaries can have trailing
|
||
# whitespace.
|
||
mo = re.search(
|
||
r'(?P<sep>' + re.escape(separator) + r')(?P<ws>[ \t]*)',
|
||
payload)
|
||
if not mo:
|
||
if self._strict:
|
||
raise Errors.BoundaryError(
|
||
"Couldn't find starting boundary: %s" % boundary)
|
||
container.set_payload(payload)
|
||
return
|
||
start = mo.start()
|
||
if start > 0:
|
||
# there's some pre-MIME boundary preamble
|
||
preamble = payload[0:start]
|
||
# Find out what kind of line endings we're using
|
||
start += len(mo.group('sep')) + len(mo.group('ws'))
|
||
mo = nlcre.search(payload, start)
|
||
if mo:
|
||
start += len(mo.group(0))
|
||
# We create a compiled regexp first because we need to be able to
|
||
# specify the start position, and the module function doesn't
|
||
# support this signature. :(
|
||
cre = re.compile('(?P<sep>\r\n|\r|\n)' +
|
||
re.escape(separator) + '--')
|
||
mo = cre.search(payload, start)
|
||
if mo:
|
||
terminator = mo.start()
|
||
linesep = mo.group('sep')
|
||
if mo.end() < len(payload):
|
||
# There's some post-MIME boundary epilogue
|
||
epilogue = payload[mo.end():]
|
||
elif self._strict:
|
||
raise Errors.BoundaryError(
|
||
"Couldn't find terminating boundary: %s" % boundary)
|
||
else:
|
||
# Handle the case of no trailing boundary. Check that it ends
|
||
# in a blank line. Some cases (spamspamspam) don't even have
|
||
# that!
|
||
mo = re.search('(?P<sep>\r\n|\r|\n){2}$', payload)
|
||
if not mo:
|
||
mo = re.search('(?P<sep>\r\n|\r|\n)$', payload)
|
||
if not mo:
|
||
raise Errors.BoundaryError(
|
||
'No terminating boundary and no trailing empty line')
|
||
linesep = mo.group('sep')
|
||
terminator = len(payload)
|
||
# We split the textual payload on the boundary separator, which
|
||
# includes the trailing newline. If the container is a
|
||
# multipart/digest then the subparts are by default message/rfc822
|
||
# instead of text/plain. In that case, they'll have a optional
|
||
# block of MIME headers, then an empty line followed by the
|
||
# message headers.
|
||
parts = re.split(
|
||
linesep + re.escape(separator) + r'[ \t]*' + linesep,
|
||
payload[start:terminator])
|
||
for part in parts:
|
||
if isdigest:
|
||
if part.startswith(linesep):
|
||
# There's no header block so create an empty message
|
||
# object as the container, and lop off the newline so
|
||
# we can parse the sub-subobject
|
||
msgobj = self._class()
|
||
part = part[len(linesep):]
|
||
else:
|
||
parthdrs, part = part.split(linesep+linesep, 1)
|
||
# msgobj in this case is the "message/rfc822" container
|
||
msgobj = self.parsestr(parthdrs, headersonly=1)
|
||
# while submsgobj is the message itself
|
||
submsgobj = self.parsestr(part)
|
||
msgobj.attach(submsgobj)
|
||
msgobj.set_default_type('message/rfc822')
|
||
else:
|
||
msgobj = self.parsestr(part)
|
||
container.preamble = preamble
|
||
container.epilogue = epilogue
|
||
container.attach(msgobj)
|
||
elif container.get_main_type() == 'multipart':
|
||
# Very bad. A message is a multipart with no boundary!
|
||
raise Errors.BoundaryError(
|
||
'multipart message with no defined boundary')
|
||
elif container.get_type() == 'message/delivery-status':
|
||
# This special kind of type contains blocks of headers separated
|
||
# by a blank line. We'll represent each header block as a
|
||
# separate Message object
|
||
blocks = []
|
||
while True:
|
||
blockmsg = self._class()
|
||
self._parseheaders(blockmsg, fp)
|
||
if not len(blockmsg):
|
||
# No more header blocks left
|
||
break
|
||
blocks.append(blockmsg)
|
||
container.set_payload(blocks)
|
||
elif container.get_main_type() == 'message':
|
||
# Create a container for the payload, but watch out for there not
|
||
# being any headers left
|
||
try:
|
||
msg = self.parse(fp)
|
||
except Errors.HeaderParseError:
|
||
msg = self._class()
|
||
self._parsebody(msg, fp)
|
||
container.attach(msg)
|
||
else:
|
||
container.set_payload(fp.read())
|
||
|
||
|
||
|
||
class HeaderParser(Parser):
|
||
"""A subclass of Parser, this one only meaningfully parses message headers.
|
||
|
||
This class can be used if all you're interested in is the headers of a
|
||
message. While it consumes the message body, it does not parse it, but
|
||
simply makes it available as a string payload.
|
||
|
||
Parsing with this subclass can be considerably faster if all you're
|
||
interested in is the message headers.
|
||
"""
|
||
def _parsebody(self, container, fp):
|
||
# Consume but do not parse, the body
|
||
container.set_payload(fp.read())
|