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MailMiner.py
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MailMiner.py
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import base64
import re
import quopri
encoded_word_regex = re.compile(r'=\?{1}(.+)\?{1}([B|Q])\?{1}(.+)\?{1}='.encode())
# https://stackoverflow.com/questions/12739563/parsing-email-bodystructure-in-python?noredirect=1
# ----- Parsing BODYSTRUCTURE into parts dictionaries ----- #
def tuple2dict(pairs):
"""get dict from (key, value, key, value, ...) tuple"""
if not pairs:
return None
return dict([(k, tuple2dict(v) if isinstance(v, tuple) else v)
for k, v in zip(pairs[::2], pairs[1::2])])
def parse_singlepart(var, part_no):
"""convert non-multipart into dic"""
# Basic fields for non-multipart (Required)
part = dict(zip(['maintype', 'subtype', 'params', 'id', 'description', 'encoding', 'size'], var[:7]), part_no=part_no)
part['params'] = tuple2dict(part['params'])
# Type specific fields (Required for 'message' or 'text' type)
index = 7
if part['maintype'].lower() in (b'message','message') and part['subtype'].lower() in (b'rfc822','rfc822'):
part.update(zip(['envelope', 'bodystructure', 'lines'], var[7:10]))
index = 10
elif part['maintype'].lower() in (b'text','text'):
part['lines'] = var[7]
index = 8
# Extension fields for non-multipart (Optional)
part.update(zip(['md5', 'disposition', 'language', 'location'], var[index:]))
part['disposition'] = tuple2dict(part['disposition'])
return part
def parse_multipart(var, part_no):
"""convert the multipart into dict"""
part = { 'child_parts': [], 'part_no': part_no }
# First parse the child parts
index = 0
if isinstance(var[0], list):
part['child_parts'] = [parse_part(v, ('%s.%d' % (part_no, i+1)).replace('TEXT.', '')) for i, v in enumerate(var[0])]
index = 1
elif isinstance(var[0], tuple):
while isinstance(var[index], tuple):
part['child_parts'].append(parse_part(var[index], ('%s.%d' % (part_no, index+1)).replace('TEXT.', '')))
index += 1
# Then parse the required field subtype and optional extension fields
part.update(zip(['subtype', 'params', 'disposition', 'language', 'location'], var[index:]))
part['params'] = tuple2dict(part['params'])
part['disposition'] = tuple2dict(part['disposition'])
return part
def parse_part(var, part_no=None):
"""Parse IMAP email BODYSTRUCTURE into nested dictionary
See http://tools.ietf.org/html/rfc3501#section-6.4.5 for structure of email messages
See http://tools.ietf.org/html/rfc3501#section-7.4.2 for specification of BODYSTRUCTURE
"""
if isinstance(var[0], (tuple, list)):
return parse_multipart(var, part_no or 'TEXT')
else:
return parse_singlepart(var, part_no or '1')
# ----- End of Parsing BODYSTRUCTURE into parts dictionaries ----- #
def FlatParts(parts, flat=None):
if flat is None:
flat = {}
child_parts = parts.get('child_parts',[])
parent_part = {k:v for k,v in parts.items() if k != 'child_parts'}
flat.update({ parent_part['part_no'] : parent_part })
for part in child_parts:
FlatParts(part,flat)
return flat
def DecodeFilename(filename):
"""Decodes a bytes filename to a standard string if it is
base64 or quopri word encoded or assumed utf-8 bytes"""
encoded = encoded_word_regex.fullmatch(filename)
if encoded:
charset, encoding, encoded_text = encoded.groups()
if encoding == b'B':
filename = base64.b64decode(encoded_text).decode(charset.decode())
elif encoding == b'Q':
filename = quopri.decodestring(encoded_text).decode(charset.decode())
else:
filename = filename.decode()
return filename
def FindAttachments(server,settings):
"""Given a server and settings containing the criteria,
Return a list of dicts of emails and all the various properties"""
# Prepare to create a dictionary
filedetails={}
# Drop readonly to allow things to be flagged as Seen
server.select_folder(settings["folder"], readonly=settings["readonly"])
# Eventually, search for emails matching the various criteria
msguids = server.search(settings["search"])
# Get structure without downloading message
allmsgstructs = server.fetch(msguids, ["BODYSTRUCTURE"])
for uid in msguids:
msgstruct = allmsgstructs[uid]
if (b"BODYSTRUCTURE" in msgstruct):
# Get all nested parts in a flat dictionary
# Find parts which are of attachment disposition
parts = FlatParts(parse_part(msgstruct[b"BODYSTRUCTURE"]))
for p in parts:
properties = {} # Specific for the part
part = parts[p]
disposition = part.get("disposition")
if disposition is not None and b"attachment" in disposition and b"filename" in disposition[b"attachment"]:
properties = disposition
# Decode file name into standard string
properties[b"filename"] = DecodeFilename(disposition[b"attachment"][b"filename"])
# Check if the filename matches the regex criteria
regexmatch = settings["regex"].fullmatch(properties[b"filename"])
print(f"File: {properties[b'filename']} in email {uid}/{p} tested as {True if regexmatch else False}")
properties.update(
{
b"uid":uid,
b"regexmatch":regexmatch,
b"encoding":part["encoding"],
b"textsize":part["size"],
b"part":p,
}
)
# If encoding is correct and filename matches the regex
if properties[b"encoding"] in (b"base64", b"7BIT") and regexmatch:
# It should already have a dict so
# add this filename and email body part number
# (which start from 1)
if uid in filedetails: filedetails[uid][p] = properties
else: filedetails[uid] = {p:properties}
return filedetails
def FetchAttachments(server,filedetails,filedata=None):
"""Given a server and list of email parts,
Returns a list of dicts containing of real file data contents
This function is memory inefficient"""
# Filedata will continue to grow with successive calls to
# FetchAttachments unless filedata is explicitly parsed
if filedata is None: filedata = []
byparts={}
batch={}
for id in filedetails:
for part in filedetails[id].keys():
# For each body[part], list the UIDs for a bulk download
byparts[part] = [id] if part not in byparts else byparts[part]+[id]
for part in byparts:
print("Starting to download a batch from the IMAP server...")
# Get the actual payload remembering that IMAP Body parts are
# indexed from 1 which has already been added,
# this will be base64 or 7BIT encoded
batch.update(
server.fetch(
byparts[part],
[f"BODY[{part}]".encode()],
)
)
print("Batch downloaded")
for uid in byparts[part]:
# Decode the data into proper bytes in each
# batch of parts and add to the big list
data = batch[uid][f"BODY[{part}]".encode()]
filedata.append(
{
"bytedata" : base64.b64decode(data) if filedetails[uid][part][b'encoding'] == b"base64" else data,
**filedetails[uid]
}
)
print(f"Decoded '{filedetails[uid][part][b'filename']}' from email {uid}/{part}")
return filedata
def FetchDecode(server,detail):
"""Fetches an email attachment and returned the decoded contents"""
print(f"Downloading email ID: {detail[b'uid']}, part: {detail[b'part']}")
# Fetches and decodes payload immediately
data = server.fetch(
detail[b"uid"],
[f"BODY[{detail[b'part']}]".encode()],
)[detail[b"uid"]][f"BODY[{detail[b'part']}]".encode()]
if detail[b"encoding"] == b"base64":
data = base64.b64decode(data)
# else, 7BIT is left as it is
print(f"Attachment: '{detail[b'filename']}', {len(data)} bytes.")
return data
if __name__ == "__main__":
import configparser
import imaplib
import Converters # Secondary Library where Converters functinos are defined
from imapclient import IMAPClient
from msal import ConfidentialClientApplication
serverconf, config = configparser.ConfigParser(), configparser.ConfigParser()
serverconf.read(r"server.cfg")
config.read(r"config.cfg")
try:
ServerSettings = dict(serverconf.items("Settings"))
clientid = ServerSettings["clientid"]
tenantid = ServerSettings["tenantid"]
imapserver = ServerSettings["server"]
scopes = [f"https://{imapserver}/.default"]
authority = f"https://login.microsoftonline.com/{tenantid}"
username = ServerSettings["username"]
password = ServerSettings["password"]
tasks = [task.strip() for task in ServerSettings["tasks"].split(",")]
if not set(tasks) <= set(config.sections()):
raise KeyError
except KeyError:
print(
"""Error with server settings in config file.
Check the "Settings" section contains the "server", "clientid",
"tenantid", "username", "password", and "tasks" options"""
)
app = ConfidentialClientApplication(
client_id = clientid, authority = authority, client_credential = password
)
token = app.acquire_token_for_client(scopes=scopes)
# Use UIDs so numbers are permanent
server = IMAPClient(imapserver, use_uid=True)
# Standard TLS version doesnt work so make the connection by hand
server._imap = imaplib.IMAP4_SSL(host=imapserver)
# Actually login and print the output while at it
print(server.oauth2_login(username, token["access_token"], mech='XOAUTH2')[0].decode())
for section in tasks:
settings = dict(config.items(section))
# Subfolder of INBOX, i.e. folder = "INBOX/Siemens Energy"
settings["folder"] = "INBOX/" + config.get(
section,"folder",fallback="",
)
# Treat the folder as readonly so nothing gets marked as read/seen
settings["readonly"] = config.getboolean(
section,"readonly",fallback=True,
)
# Split words by spaces into a list, i.e. searchcriteria = ["ALL"]
settings["search"] = config.get(
section,"search",fallback="ALL",
).split(" ")
# Convert regex string to bytes
# i.e. regex = re.compile(rb"UVW_[0-9]{6}_to_[0-9]{6}_produced_at_[0-9]{6}\.csv")
settings["regex"] = re.compile(
config.get(
section,"filename",fallback=None,
)
)
if "filename" not in settings or settings["filename"] == "":
print(
"""There was no "filename" option given, or it was empty.
A regex was expected. This section will be skipped"""
)
continue
# The output file name
settings["outfile"] = config.get(
section,"outfile",fallback="output.csv"
)
print(
f"""Section: "{section}"
Folder: "{settings["folder"]}"
Read Only: "{settings["readonly"]}"
Criteria: "{settings["search"]}"
Regex: "{settings["filename"]}"
outfile: "{settings["outfile"]}"
"""
)
# Get all the attachment details
filedetails = FindAttachments(server,settings)
print(f"Found {len(filedetails)} attachments")
# Generator Expression where each element is a copy of
# the original filedetails dictionary along with the
# bytedata after fetching, downloading and decoding it
if len(filedetails) > 0:
filedata = (
{
"bytedata":FetchDecode(server,part),
**part,
} for msg in filedetails.values() for part in msg.values()
)
# Runs the named function directly from the local scope
getattr(Converters,
config.get(
section,
"converter",
fallback="Shelve",
)
)(filedata,settings)
print(server.logout().decode())