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# -*- coding: utf-8 -*-
# walk.py
# Copyright (C) 2013 LEAP
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
Utilities for walking along a message tree.
"""
import hashlib
import os
from leap.mail.utils import first
DEBUG = os.environ.get("BITMASK_MAIL_DEBUG")
if DEBUG:
get_hash = lambda s: hashlib.sha256(s).hexdigest()[:10]
else:
get_hash = lambda s: hashlib.sha256(s).hexdigest()
"""
Get interesting message parts
"""
get_parts = lambda msg: [
{'multi': part.is_multipart(),
'ctype': part.get_content_type(),
'size': len(part.as_string()),
'parts': len(part.get_payload())
if isinstance(part.get_payload(), list)
else 1,
'headers': part.items(),
'phash': get_hash(part.get_payload())
if not part.is_multipart() else None}
for part in msg.walk()]
"""
Utility lambda functions for getting the parts vector and the
payloads from the original message.
"""
get_parts_vector = lambda parts: (x.get('parts', 1) for x in parts)
get_payloads = lambda msg: ((x.get_payload(),
dict(((str.lower(k), v) for k, v in (x.items()))))
for x in msg.walk())
get_body_phash_simple = lambda payloads: first(
[get_hash(payload) for payload, headers in payloads
if payloads])
get_body_phash_multi = lambda payloads: (first(
[get_hash(payload) for payload, headers in payloads
if payloads
and "text/plain" in headers.get('content-type', '')])
or get_body_phash_simple(payloads))
"""
On getting the raw docs, we get also some of the headers to be able to
index the content. Here we remove any mutable part, as the the filename
in the content disposition.
"""
get_raw_docs = lambda msg, parts: (
{"type": "cnt", # type content they'll be
"raw": payload if not DEBUG else payload[:100],
"phash": get_hash(payload),
"content-disposition": first(headers.get(
'content-disposition', '').split(';')),
"content-type": headers.get(
'content-type', ''),
"content-transfer-encoding": headers.get(
'content-transfer-type', '')}
for payload, headers in get_payloads(msg)
if not isinstance(payload, list))
def walk_msg_tree(parts, body_phash=None):
"""
Take a list of interesting items of a message subparts structure,
and return a dict of dicts almost ready to be written to the content
documents that will be stored in Soledad.
It walks down the subparts in the parsed message tree, and collapses
the leaf docuents into a wrapper document until no multipart submessages
are left. To achieve this, it iteratively calculates a wrapper vector of
all documents in the sequence that have more than one part and have unitary
documents to their right. To collapse a multipart, take as many
unitary documents as parts the submessage contains, and replace the object
in the sequence with the new wrapper document.
:param parts: A list of dicts containing the interesting properties for
the message structure. Normally this has been generated by
doing a message walk.
:type parts: list of dicts.
:param body_phash: the payload hash of the body part, to be included
in the outer content doc for convenience.
:type body_phash: basestring or None
"""
# parts vector
pv = list(get_parts_vector(parts))
inner_headers = parts[1].get("headers", None) if (
len(parts) == 2) else None
if DEBUG:
print "parts vector: ", pv
print
# wrappers vector
getwv = lambda pv: [True if pv[i] != 1 and pv[i + 1] == 1 else False
for i in range(len(pv) - 1)]
wv = getwv(pv)
# do until no wrapper document is left
while any(wv):
wind = wv.index(True) # wrapper index
nsub = pv[wind] # number of subparts to pick
slic = parts[wind + 1:wind + 1 + nsub] # slice with subparts
cwra = {
"multi": True,
"part_map": dict((index + 1, part) # content wrapper
for index, part in enumerate(slic)),
"headers": dict(parts[wind]['headers'])
}
# remove subparts and substitue wrapper
map(lambda i: parts.remove(i), slic)
parts[wind] = cwra
# refresh vectors for this iteration
pv = list(get_parts_vector(parts))
wv = getwv(pv)
outer = parts[0]
outer.pop('headers')
if not "part_map" in outer:
# we have a multipart with 1 part only, so kind of fix it
# although it would be prettier if I take this special case at
# the beginning of the walk.
pdoc = {"multi": True,
"part_map": {1: outer}}
pdoc["part_map"][1]["multi"] = False
if not pdoc["part_map"][1].get("phash", None):
pdoc["part_map"][1]["phash"] = body_phash
if inner_headers:
pdoc["part_map"][1]["headers"] = inner_headers
else:
pdoc = outer
pdoc["body"] = body_phash
return pdoc
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