197 lines
7.9 KiB
Python
197 lines
7.9 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'
|
||
|
||
|
||
|
||
class Parser:
|
||
def __init__(self, _class=Message.Message):
|
||
"""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.
|
||
"""
|
||
self._class = _class
|
||
|
||
def parse(self, fp):
|
||
root = self._class()
|
||
self._parseheaders(root, fp)
|
||
self._parsebody(root, fp)
|
||
return root
|
||
|
||
def parsestr(self, text):
|
||
return self.parse(StringIO(text))
|
||
|
||
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 1:
|
||
# 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
|
||
else:
|
||
raise Errors.HeaderParseError(
|
||
'Unix-from in headers after first rfc822 header')
|
||
# 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:
|
||
raise Errors.HeaderParseError(
|
||
'Not a header, not a continuation')
|
||
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_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
|
||
# have the leading newline since we're at the start of the body
|
||
# text.
|
||
separator = '--' + boundary
|
||
payload = fp.read()
|
||
start = payload.find(separator)
|
||
if start < 0:
|
||
raise Errors.BoundaryError(
|
||
"Couldn't find starting boundary: %s" % boundary)
|
||
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(separator)
|
||
cre = re.compile('\r\n|\r|\n')
|
||
mo = cre.search(payload, start)
|
||
if mo:
|
||
start += len(mo.group(0)) * (1 + isdigest)
|
||
# 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 not mo:
|
||
raise Errors.BoundaryError(
|
||
"Couldn't find terminating boundary: %s" % boundary)
|
||
terminator = mo.start()
|
||
linesep = mo.group('sep')
|
||
if mo.end() < len(payload):
|
||
# there's some post-MIME boundary epilogue
|
||
epilogue = payload[mo.end():]
|
||
# 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 an extra
|
||
# newline before the headers to distinguish the message's headers
|
||
# from the subpart headers.
|
||
separator += linesep * (1 + isdigest)
|
||
parts = payload[start:terminator].split(linesep + separator)
|
||
for part in parts:
|
||
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 1:
|
||
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())
|