387 lines
15 KiB
Python
387 lines
15 KiB
Python
# Copyright (C) 2001 Python Software Foundation
|
||
# Author: barry@zope.com (Barry Warsaw)
|
||
|
||
"""Classes to generate plain text from a message object tree.
|
||
"""
|
||
|
||
import time
|
||
import re
|
||
import random
|
||
|
||
from types import ListType, StringType
|
||
from cStringIO import StringIO
|
||
|
||
# Intrapackage imports
|
||
import Message
|
||
import Errors
|
||
|
||
EMPTYSTRING = ''
|
||
SEMISPACE = '; '
|
||
BAR = '|'
|
||
UNDERSCORE = '_'
|
||
NL = '\n'
|
||
NLTAB = '\n\t'
|
||
SEMINLTAB = ';\n\t'
|
||
SPACE8 = ' ' * 8
|
||
|
||
fcre = re.compile(r'^From ', re.MULTILINE)
|
||
|
||
|
||
|
||
class Generator:
|
||
"""Generates output from a Message object tree.
|
||
|
||
This basic generator writes the message to the given file object as plain
|
||
text.
|
||
"""
|
||
#
|
||
# Public interface
|
||
#
|
||
|
||
def __init__(self, outfp, mangle_from_=1, maxheaderlen=78):
|
||
"""Create the generator for message flattening.
|
||
|
||
outfp is the output file-like object for writing the message to. It
|
||
must have a write() method.
|
||
|
||
Optional mangle_from_ is a flag that, when true, escapes From_ lines
|
||
in the body of the message by putting a `>' in front of them.
|
||
|
||
Optional maxheaderlen specifies the longest length for a non-continued
|
||
header. When a header line is longer (in characters, with tabs
|
||
expanded to 8 spaces), than maxheaderlen, the header will be broken on
|
||
semicolons and continued as per RFC 2822. If no semicolon is found,
|
||
then the header is left alone. Set to zero to disable wrapping
|
||
headers. Default is 78, as recommended (but not required by RFC
|
||
2822.
|
||
"""
|
||
self._fp = outfp
|
||
self._mangle_from_ = mangle_from_
|
||
self.__first = 1
|
||
self.__maxheaderlen = maxheaderlen
|
||
|
||
def write(self, s):
|
||
# Just delegate to the file object
|
||
self._fp.write(s)
|
||
|
||
def __call__(self, msg, unixfrom=0):
|
||
"""Print the message object tree rooted at msg to the output file
|
||
specified when the Generator instance was created.
|
||
|
||
unixfrom is a flag that forces the printing of a Unix From_ delimiter
|
||
before the first object in the message tree. If the original message
|
||
has no From_ delimiter, a `standard' one is crafted. By default, this
|
||
is 0 to inhibit the printing of any From_ delimiter.
|
||
|
||
Note that for subobjects, no From_ line is printed.
|
||
"""
|
||
if unixfrom:
|
||
ufrom = msg.get_unixfrom()
|
||
if not ufrom:
|
||
ufrom = 'From nobody ' + time.ctime(time.time())
|
||
print >> self._fp, ufrom
|
||
self._write(msg)
|
||
|
||
#
|
||
# Protected interface - undocumented ;/
|
||
#
|
||
|
||
def _write(self, msg):
|
||
# We can't write the headers yet because of the following scenario:
|
||
# say a multipart message includes the boundary string somewhere in
|
||
# its body. We'd have to calculate the new boundary /before/ we write
|
||
# the headers so that we can write the correct Content-Type:
|
||
# parameter.
|
||
#
|
||
# The way we do this, so as to make the _handle_*() methods simpler,
|
||
# is to cache any subpart writes into a StringIO. The we write the
|
||
# headers and the StringIO contents. That way, subpart handlers can
|
||
# Do The Right Thing, and can still modify the Content-Type: header if
|
||
# necessary.
|
||
oldfp = self._fp
|
||
try:
|
||
self._fp = sfp = StringIO()
|
||
self._dispatch(msg)
|
||
finally:
|
||
self._fp = oldfp
|
||
# Write the headers. First we see if the message object wants to
|
||
# handle that itself. If not, we'll do it generically.
|
||
meth = getattr(msg, '_write_headers', None)
|
||
if meth is None:
|
||
self._write_headers(msg)
|
||
else:
|
||
meth(self)
|
||
self._fp.write(sfp.getvalue())
|
||
|
||
def _dispatch(self, msg):
|
||
# Get the Content-Type: for the message, then try to dispatch to
|
||
# self._handle_maintype_subtype(). If there's no handler for the full
|
||
# MIME type, then dispatch to self._handle_maintype(). If that's
|
||
# missing too, then dispatch to self._writeBody().
|
||
ctype = msg.get_type()
|
||
if ctype is None:
|
||
# No Content-Type: header so try the default handler
|
||
self._writeBody(msg)
|
||
else:
|
||
# We do have a Content-Type: header.
|
||
specific = UNDERSCORE.join(ctype.split('/')).replace('-', '_')
|
||
meth = getattr(self, '_handle_' + specific, None)
|
||
if meth is None:
|
||
generic = msg.get_main_type().replace('-', '_')
|
||
meth = getattr(self, '_handle_' + generic, None)
|
||
if meth is None:
|
||
meth = self._writeBody
|
||
meth(msg)
|
||
|
||
#
|
||
# Default handlers
|
||
#
|
||
|
||
def _write_headers(self, msg):
|
||
for h, v in msg.items():
|
||
# We only write the MIME-Version: header for the outermost
|
||
# container message. Unfortunately, we can't use same technique
|
||
# as for the Unix-From above because we don't know when
|
||
# MIME-Version: will occur.
|
||
if h.lower() == 'mime-version' and not self.__first:
|
||
continue
|
||
# RFC 2822 says that lines SHOULD be no more than maxheaderlen
|
||
# characters wide, so we're well within our rights to split long
|
||
# headers.
|
||
text = '%s: %s' % (h, v)
|
||
if self.__maxheaderlen > 0 and len(text) > self.__maxheaderlen:
|
||
text = self._split_header(text)
|
||
print >> self._fp, text
|
||
# A blank line always separates headers from body
|
||
print >> self._fp
|
||
|
||
def _split_header(self, text):
|
||
maxheaderlen = self.__maxheaderlen
|
||
# Find out whether any lines in the header are really longer than
|
||
# maxheaderlen characters wide. There could be continuation lines
|
||
# that actually shorten it. Also, replace hard tabs with 8 spaces.
|
||
lines = [s.replace('\t', SPACE8) for s in text.split('\n')]
|
||
for line in lines:
|
||
if len(line) > maxheaderlen:
|
||
break
|
||
else:
|
||
# No line was actually longer than maxheaderlen characters, so
|
||
# just return the original unchanged.
|
||
return text
|
||
rtn = []
|
||
for line in text.split('\n'):
|
||
# Short lines can remain unchanged
|
||
if len(line.replace('\t', SPACE8)) <= maxheaderlen:
|
||
rtn.append(line)
|
||
SEMINLTAB.join(rtn)
|
||
else:
|
||
oldlen = len(text)
|
||
# Try to break the line on semicolons, but if that doesn't
|
||
# work, try to split on folding whitespace.
|
||
while len(text) > maxheaderlen:
|
||
i = text.rfind(';', 0, maxheaderlen)
|
||
if i < 0:
|
||
break
|
||
rtn.append(text[:i])
|
||
text = text[i+1:].lstrip()
|
||
if len(text) <> oldlen:
|
||
# Splitting on semis worked
|
||
rtn.append(text)
|
||
return SEMINLTAB.join(rtn)
|
||
# Splitting on semis didn't help, so try to split on
|
||
# whitespace.
|
||
parts = re.split(r'(\s+)', text)
|
||
# Watch out though for "Header: longnonsplittableline"
|
||
if parts[0].endswith(':') and len(parts) == 3:
|
||
return text
|
||
first = parts.pop(0)
|
||
sublines = [first]
|
||
acc = len(first)
|
||
while parts:
|
||
len0 = len(parts[0])
|
||
len1 = len(parts[1])
|
||
if acc + len0 + len1 < maxheaderlen:
|
||
sublines.append(parts.pop(0))
|
||
sublines.append(parts.pop(0))
|
||
acc += len0 + len1
|
||
else:
|
||
# Split it here, but don't forget to ignore the
|
||
# next whitespace-only part
|
||
rtn.append(EMPTYSTRING.join(sublines))
|
||
del parts[0]
|
||
first = parts.pop(0)
|
||
sublines = [first]
|
||
acc = len(first)
|
||
rtn.append(EMPTYSTRING.join(sublines))
|
||
return NLTAB.join(rtn)
|
||
|
||
#
|
||
# Handlers for writing types and subtypes
|
||
#
|
||
|
||
def _handle_text(self, msg):
|
||
payload = msg.get_payload()
|
||
if payload is None:
|
||
return
|
||
if not isinstance(payload, StringType):
|
||
raise TypeError, 'string payload expected: %s' % type(payload)
|
||
if self._mangle_from_:
|
||
payload = fcre.sub('>From ', payload)
|
||
self._fp.write(payload)
|
||
|
||
# Default body handler
|
||
_writeBody = _handle_text
|
||
|
||
def _handle_multipart(self, msg, isdigest=0):
|
||
# The trick here is to write out each part separately, merge them all
|
||
# together, and then make sure that the boundary we've chosen isn't
|
||
# present in the payload.
|
||
msgtexts = []
|
||
for part in msg.get_payload():
|
||
s = StringIO()
|
||
g = self.__class__(s, self._mangle_from_, self.__maxheaderlen)
|
||
g(part, unixfrom=0)
|
||
msgtexts.append(s.getvalue())
|
||
# Now make sure the boundary we've selected doesn't appear in any of
|
||
# the message texts.
|
||
alltext = NL.join(msgtexts)
|
||
# BAW: What about boundaries that are wrapped in double-quotes?
|
||
boundary = msg.get_boundary(failobj=_make_boundary(alltext))
|
||
# If we had to calculate a new boundary because the body text
|
||
# contained that string, set the new boundary. We don't do it
|
||
# unconditionally because, while set_boundary() preserves order, it
|
||
# doesn't preserve newlines/continuations in headers. This is no big
|
||
# deal in practice, but turns out to be inconvenient for the unittest
|
||
# suite.
|
||
if msg.get_boundary() <> boundary:
|
||
msg.set_boundary(boundary)
|
||
# Write out any preamble
|
||
if msg.preamble is not None:
|
||
self._fp.write(msg.preamble)
|
||
# First boundary is a bit different; it doesn't have a leading extra
|
||
# newline.
|
||
print >> self._fp, '--' + boundary
|
||
if isdigest:
|
||
print >> self._fp
|
||
# Join and write the individual parts
|
||
joiner = '\n--' + boundary + '\n'
|
||
if isdigest:
|
||
# multipart/digest types effectively add an extra newline between
|
||
# the boundary and the body part.
|
||
joiner += '\n'
|
||
self._fp.write(joiner.join(msgtexts))
|
||
print >> self._fp, '\n--' + boundary + '--',
|
||
# Write out any epilogue
|
||
if msg.epilogue is not None:
|
||
if not msg.epilogue.startswith('\n'):
|
||
print >> self._fp
|
||
self._fp.write(msg.epilogue)
|
||
|
||
def _handle_multipart_digest(self, msg):
|
||
self._handle_multipart(msg, isdigest=1)
|
||
|
||
def _handle_message_delivery_status(self, msg):
|
||
# We can't just write the headers directly to self's file object
|
||
# because this will leave an extra newline between the last header
|
||
# block and the boundary. Sigh.
|
||
blocks = []
|
||
for part in msg.get_payload():
|
||
s = StringIO()
|
||
g = self.__class__(s, self._mangle_from_, self.__maxheaderlen)
|
||
g(part, unixfrom=0)
|
||
text = s.getvalue()
|
||
lines = text.split('\n')
|
||
# Strip off the unnecessary trailing empty line
|
||
if lines and lines[-1] == '':
|
||
blocks.append(NL.join(lines[:-1]))
|
||
else:
|
||
blocks.append(text)
|
||
# Now join all the blocks with an empty line. This has the lovely
|
||
# effect of separating each block with an empty line, but not adding
|
||
# an extra one after the last one.
|
||
self._fp.write(NL.join(blocks))
|
||
|
||
def _handle_message(self, msg):
|
||
s = StringIO()
|
||
g = self.__class__(s, self._mangle_from_, self.__maxheaderlen)
|
||
# A message/rfc822 should contain a scalar payload which is another
|
||
# Message object. Extract that object, stringify it, and write that
|
||
# out.
|
||
g(msg.get_payload(), unixfrom=0)
|
||
self._fp.write(s.getvalue())
|
||
|
||
|
||
|
||
class DecodedGenerator(Generator):
|
||
"""Generator a text representation of a message.
|
||
|
||
Like the Generator base class, except that non-text parts are substituted
|
||
with a format string representing the part.
|
||
"""
|
||
def __init__(self, outfp, mangle_from_=1, maxheaderlen=78, fmt=None):
|
||
"""Like Generator.__init__() except that an additional optional
|
||
argument is allowed.
|
||
|
||
Walks through all subparts of a message. If the subpart is of main
|
||
type `text', then it prints the decoded payload of the subpart.
|
||
|
||
Otherwise, fmt is a format string that is used instead of the message
|
||
payload. fmt is expanded with the following keywords (in
|
||
%(keyword)s format):
|
||
|
||
type : Full MIME type of the non-text part
|
||
maintype : Main MIME type of the non-text part
|
||
subtype : Sub-MIME type of the non-text part
|
||
filename : Filename of the non-text part
|
||
description: Description associated with the non-text part
|
||
encoding : Content transfer encoding of the non-text part
|
||
|
||
The default value for fmt is None, meaning
|
||
|
||
[Non-text (%(type)s) part of message omitted, filename %(filename)s]
|
||
"""
|
||
Generator.__init__(self, outfp, mangle_from_, maxheaderlen)
|
||
if fmt is None:
|
||
fmt = ('[Non-text (%(type)s) part of message omitted, '
|
||
'filename %(filename)s]')
|
||
self._fmt = fmt
|
||
|
||
def _dispatch(self, msg):
|
||
for part in msg.walk():
|
||
maintype = part.get_main_type('text')
|
||
if maintype == 'text':
|
||
print >> self, part.get_payload(decode=1)
|
||
elif maintype == 'multipart':
|
||
# Just skip this
|
||
pass
|
||
else:
|
||
print >> self, self._fmt % {
|
||
'type' : part.get_type('[no MIME type]'),
|
||
'maintype' : part.get_main_type('[no main MIME type]'),
|
||
'subtype' : part.get_subtype('[no sub-MIME type]'),
|
||
'filename' : part.get_filename('[no filename]'),
|
||
'description': part.get('Content-Description',
|
||
'[no description]'),
|
||
'encoding' : part.get('Content-Transfer-Encoding',
|
||
'[no encoding]'),
|
||
}
|
||
|
||
|
||
|
||
# Helper
|
||
def _make_boundary(self, text=None):
|
||
# Craft a random boundary. If text is given, ensure that the chosen
|
||
# boundary doesn't appear in the text.
|
||
boundary = ('=' * 15) + repr(random.random()).split('.')[1] + '=='
|
||
if text is None:
|
||
return boundary
|
||
b = boundary
|
||
counter = 0
|
||
while 1:
|
||
cre = re.compile('^--' + re.escape(b) + '(--)?$', re.MULTILINE)
|
||
if not cre.search(text):
|
||
break
|
||
b = boundary + '.' + str(counter)
|
||
counter += 1
|
||
return b
|