260 lines
9.8 KiB
Python
260 lines
9.8 KiB
Python
# PyQuarantine-Milter is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# PyQuarantine-Milter is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with PyQuarantineMilter. If not, see <http://www.gnu.org/licenses/>.
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#
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import email
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import logging
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import re
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from bs4 import BeautifulSoup
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from cgi import escape
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from email.mime.multipart import MIMEMultipart
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from email.mime.text import MIMEText
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from email.mime.image import MIMEImage
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from pyquarantine import mailer
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class BaseNotification(object):
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"Notification base class"
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def __init__(self, global_config, config, configtest=False):
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self.quarantine_name = config["name"]
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self.global_config = global_config
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self.config = config
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self.logger = logging.getLogger(__name__)
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def notify(self, queueid, quarantine_id, subject, mailfrom, recipients, fp):
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fp.seek(0)
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pass
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class EMailNotification(BaseNotification):
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"Notification class to send notifications via mail."
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_html_text = "text/html"
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_plain_text = "text/plain"
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_bad_tags = [
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"applet",
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"embed",
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"frame",
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"frameset",
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"head",
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"iframe",
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"script"
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]
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_good_tags = [
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"a",
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"b",
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"br",
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"center",
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"div",
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"font",
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"h1",
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"h2",
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"h3",
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"h4",
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"h5",
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"h6",
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"i",
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"img",
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"li",
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"span",
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"table",
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"td",
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"th",
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"tr",
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"tt",
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"u",
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"ul"
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]
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good_attributes = [
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"align",
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"alt",
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"bgcolor",
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"border",
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"cellpadding",
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"cellspacing",
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"color",
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"colspan",
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"dir",
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"face",
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"headers",
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"height",
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"id",
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"name",
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"rowspan",
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"size",
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"src",
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"style",
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"title",
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"type",
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"valign",
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"value",
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"width"
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]
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def __init__(self, global_config, config, configtest=False):
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super(EMailNotification, self).__init__(global_config, config, configtest)
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# check if mandatory options are present in config
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for option in ["smtp_host", "smtp_port", "notification_email_from", "notification_email_subject", "notification_email_template", "notification_email_replacement_img"]:
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if option not in self.config.keys() and option in self.global_config.keys():
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self.config[option] = self.global_config[option]
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if option not in self.config.keys():
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raise RuntimeError("mandatory option '{}' not present in config section '{}' or 'global'".format(option, self.quarantine_name))
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self.smtp_host = self.config["smtp_host"]
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self.smtp_port = self.config["smtp_port"]
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self.mailfrom = self.config["notification_email_from"]
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self.subject = self.config["notification_email_subject"]
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# read email notification template
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try:
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self.template = open(self.config["notification_email_template"], "r").read()
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except IOError as e:
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raise RuntimeError("error reading template: {}".format(e))
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# read email replacement image
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try:
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self.replacement_img = MIMEImage(open(self.config["notification_email_replacement_img"], "rb").read())
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except IOError as e:
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raise RuntimeError("error reading replacement image: {}".format(e))
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else:
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self.replacement_img.add_header("Content-ID", "<removed_for_security_reasons>")
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def get_text(self, queueid, part):
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"Get the mail text in html form from email part."
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mimetype = part.get_content_type()
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self.logger.debug("{}: extracting content of email text part".format(queueid))
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text = part.get_payload(decode=True)
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if mimetype == EMailNotification._plain_text:
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self.logger.debug("{}: content mimetype is {}, converting to {}".format(queueid, mimetype, self._html_text))
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text = re.sub(r"^(.*)$", r"\1<br/>\n", text.decode(), flags=re.MULTILINE)
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else:
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self.logger.debug("{}: content mimetype is {}".format(queueid, mimetype))
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return BeautifulSoup(text, "lxml", from_encoding=part.get_content_charset())
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def get_text_multipart(self, queueid, msg, preferred=_html_text):
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"Get the mail text of a multipart email in html form."
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soup = None
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for part in msg.get_payload():
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mimetype = part.get_content_type()
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if mimetype in [EMailNotification._plain_text, EMailNotification._html_text]:
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soup = self.get_text(queueid, part)
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elif mimetype.startswith("multipart"):
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soup = self.get_text_multipart(queueid, part, preferred)
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if soup != None and mimetype == preferred:
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break
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return soup
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def sanitize(self, queueid, soup):
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"Sanitize mail html text."
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self.logger.debug("{}: sanitizing email text".format(queueid))
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# completly remove bad elements
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for element in soup(EMailNotification._bad_tags):
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self.logger.debug("{}: removing dangerous tag '{}' and its content".format(queueid, element.name))
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element.extract()
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# remove not whitelisted elements, but keep their content
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for element in soup.find_all(True):
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if element.name not in EMailNotification._good_tags:
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self.logger.debug("{}: removing tag '{}', keep its content".format(queueid, element.name))
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element.replaceWithChildren()
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# remove not whitelisted attributes
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for element in soup.find_all(True):
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for attribute in element.attrs.keys():
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if attribute not in EMailNotification.good_attributes:
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if element.name == "a" and attribute == "href":
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self.logger.debug("{}: setting attribute href to '#' on tag '{}'".format(queueid, element.name))
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element["href"] = "#"
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else:
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self.logger.debug("{}: removing attribute '{}' from tag '{}'".format(queueid, attribute, element.name))
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del(element.attrs[attribute])
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return soup
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def get_html_text_part(self, queueid, msg):
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"Get the mail text of an email in html form."
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soup = None
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mimetype = msg.get_content_type()
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self.logger.debug("{}: trying to find text part of email".format(queueid))
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if mimetype in [EMailNotification._plain_text, EMailNotification._html_text]:
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soup = self.get_text(queueid, msg)
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elif mimetype.startswith("multipart"):
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soup = self.get_text_multipart(queueid, msg)
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if soup == None:
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self.logger.error("{}: unable to extract text part of email".format(queueid))
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text = "ERROR: unable to extract text from email body"
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soup = BeautifulSoup(text, "lxml", "UTF-8")
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return soup
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def notify(self, queueid, quarantine_id, subject, mailfrom, recipients, fp):
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"Notify recipients via email."
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super(EMailNotification, self).notify(queueid, quarantine_id, subject, mailfrom, recipients, fp)
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# extract html text from email
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self.logger.debug("{}: extraction email text from original email".format(queueid))
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soup = self.get_html_text_part(queueid, email.message_from_binary_file(fp))
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# replace picture sources
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picture_replaced = False
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for element in soup("img"):
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if "src" in element.attrs.keys():
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self.logger.debug("{}: replacing image: {}".format(queueid, element["src"]))
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element["src"] = "cid:removed_for_security_reasons"
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picture_replaced = True
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# sanitizing email text of original email
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sanitized_text = self.sanitize(queueid, soup)
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# escape possible html entities in subject
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subject = escape(subject)
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# sending email notifications
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for recipient in recipients:
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self.logger.debug("{}: generating notification email for '{}'".format(queueid, recipient))
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self.logger.debug("{}: parsing email template".format(queueid))
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htmltext = self.template.format( \
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EMAIL_HTML_TEXT=sanitized_text, \
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EMAIL_FROM=escape(mailfrom), \
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EMAIL_TO=escape(recipient), \
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EMAIL_SUBJECT=subject, \
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EMAIL_QUARANTINE_ID=quarantine_id
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)
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msg = MIMEMultipart('alternative')
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msg["Subject"] = self.subject
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msg["From"] = "<{}>".format(self.mailfrom)
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msg["To"] = "<{}>".format(recipient)
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msg["Date"] = email.utils.formatdate()
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msg.attach(MIMEText(htmltext, "html", 'UTF-8'))
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if picture_replaced:
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self.logger.debug("{}: attaching notification_replacement_img".format(queueid))
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msg.attach(self.replacement_img)
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self.logger.debug("{}: sending notification email to: {}".format(queueid, recipient))
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mailer.sendmail(self.smtp_host, self.smtp_port, queueid, self.mailfrom, recipient, msg.as_string(), "notification email")
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# list of notification types and their related notification classes
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TYPES = {"email": EMailNotification}
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