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https://gitea.mueller.network/extern/django-helpdesk.git
synced 2024-12-24 15:48:49 +01:00
Process email content first then focus on attachments.
Use the EmailMessage class for enhanced processing.
This commit is contained in:
Christopher Broderick
parent
3f8c718d71
commit
8006826ddf
@ -16,7 +16,8 @@ from django.db.models import Q
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from django.utils import encoding, timezone
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from django.utils.translation import gettext as _
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import email
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from email.message import Message
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from email import policy
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from email.message import EmailMessage, MIMEPart
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from email.mime.text import MIMEText
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from email.utils import getaddresses
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from email_reply_parser import EmailReplyParser
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@ -52,6 +53,7 @@ STRIPPED_SUBJECT_STRINGS = [
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"Automatic reply: ",
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]
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# Allow a custom default attached email name for the HTML formatted email if one is found
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HTML_EMAIL_ATTACHMENT_FILENAME = _("email_html_body.html")
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@ -426,7 +428,7 @@ def process_queue(q, logger):
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def decodeUnknown(charset, string):
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if type(string) is not str:
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if string and not isinstance(string, str):
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if not charset:
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try:
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return str(string, encoding='utf-8', errors='replace')
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@ -717,7 +719,7 @@ def attempt_body_extract_from_html(message: str) -> str:
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return body, full_body
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def extract_mime_content(part: Message,) -> str:
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def mime_content_to_string(part: EmailMessage,) -> str:
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'''
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Extract the content from the MIME body part
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:param part: the MIME part to extract the content from
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@ -732,19 +734,82 @@ def extract_mime_content(part: Message,) -> str:
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return content
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def extract_email_message(mime_content: str, is_plain_content_type: bool, is_extract_full_email_msg: bool) -> str:
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email_content = None
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def parse_email_content(mime_content: str, is_extract_full_email_msg: bool) -> str:
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if is_extract_full_email_msg:
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# Take the full content including encapsulated "forwarded" and "reply" sections
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email_content = get_body_from_fragments(mime_content) if is_plain_content_type else mime_content
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return mime_content
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else:
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# Just get the primary part of the email and drop off any text below the actually response text
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email_content = EmailReplyParser.parse_reply(mime_content) if is_plain_content_type else mime_content
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return email_content
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# Just get the primary part of the email and drop off any text below the actual response text
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return EmailReplyParser.parse_reply(mime_content)
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def extract_email_message_content(
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part: MIMEPart,
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files: List,
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include_chained_msgs: bool,
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) -> (str, str):
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'''
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Uses the get_body() method of the email package to extract the email message content.
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If there is an HTML version of the email message content then it is stored as an attachment.
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If there is a plain text part then that is used for storing the email content aginst the ticket.
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Otherwise if there is just an HTML part then the HTML is parsed to extract a simple text message.
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There is special handling for the case when a multipart/related part holds the message content when
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there are multiple attachments to the email.
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:param part: the base email MIME part to be searched
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:param files: any MIME parts to be attached are added to this list
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:param include_chained_msgs: flag to indicate if the entire email message content including past replies must be extracted
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'''
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message_part:MIMEPart = part.get_body()
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parent_part:MIMEPart = part
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content_type = message_part.get_content_type()
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# Handle the possibility of a related part formatted email
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if "multipart/related" == content_type:
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# We want the actual message text so try again on the related MIME part
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parent_part = message_part
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message_part = message_part.get_body(preferencelist=["html", "plain",])
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content_type = message_part.get_content_type()
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mime_content = None
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formatted_body = None # Retain the original content by using a secondary variable if the HTML needs wrapping
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if "text/html" == content_type:
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# add the HTML message as an attachment wrapping if necessary
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mime_content = mime_content_to_string(message_part)
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if "<body" not in mime_content:
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formatted_body = f"<body>{mime_content}</body>"
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if "<html" not in mime_content:
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formatted_body = f"<html><head><meta charset=\"utf-8\" /></head>{mime_content if formatted_body is None else formatted_body}</html>"
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files.append(
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SimpleUploadedFile(
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HTML_EMAIL_ATTACHMENT_FILENAME, (mime_content if formatted_body is None else formatted_body).encode("utf-8"), 'text/html')
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)
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# Try to get a plain part message
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plain_message_part = parent_part.get_body(preferencelist=["plain",])
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if plain_message_part:
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# Replace mime_content with the plain text part content
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mime_content = mime_content_to_string(plain_message_part)
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message_part = plain_message_part
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content_type = "text/plain"
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else:
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# Try to constitute the HTML response as plain text
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mime_content, _x = attempt_body_extract_from_html(mime_content if formatted_body is None else formatted_body)
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else:
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# Is either text/plain or some random content-type so just decode the part content and store as is
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mime_content = mime_content_to_string(message_part)
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# We should now have the mime content
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filtered_body = parse_email_content(mime_content, include_chained_msgs)
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if not filtered_body or "" == filtered_body.strip():
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# A unit test that has a different HTML content to plain text which seems an invalid case as email
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# tools should retain the HTML to be consistent with the plain text but manage this as a special case
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# Try to constitute the HTML response as plain text
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if formatted_body:
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filtered_body, _x = attempt_body_extract_from_html(formatted_body)
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else:
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filtered_body = mime_content
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# Only need the full message if the message_body excludes the chained messages
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return filtered_body, mime_content
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def process_as_attachment(
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part: Message,
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part: MIMEPart,
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counter: int,
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files: List,
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logger: logging.Logger
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@ -756,14 +821,14 @@ def process_as_attachment(
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ext = mimetypes.guess_extension(part.get_content_type())
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name = f"part-{counter}{ext}"
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# Extract payload accounting for attached multiparts
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payload = part.as_string() if part.is_multipart() else part.get_payload(decode=True)
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files.append(SimpleUploadedFile(name, payload, mimetypes.guess_type(name)[0]))
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payload_bytes = part.as_bytes() if part.is_multipart() else part.get_payload(decode=True)
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files.append(SimpleUploadedFile(name, payload_bytes, mimetypes.guess_type(name)[0]))
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if logger.isEnabledFor(logging.DEBUG):
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logger.debug("Processed MIME as attachment: %s", name)
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return
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def extract_email_subject(email_msg: Message,) -> str:
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def extract_email_subject(email_msg: EmailMessage,) -> str:
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subject = email_msg.get('subject', _('Comment from e-mail'))
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subject = decode_mail_headers(
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decodeUnknown(email_msg.get_charset(), subject))
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@ -772,6 +837,62 @@ def extract_email_subject(email_msg: Message,) -> str:
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return subject.strip()
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def extract_attachments(
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target_part: MIMEPart,
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files: List,
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logger: logging.Logger,
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counter: int = 1,
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content_parts_excluded: bool = False,
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) -> (int, bool):
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'''
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if the MIME part is a multipart and not identified as inline or attachment then
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iterate over the sub parts recursively.
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Otherwise extract \MIME part content and add as an attachment.
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It will recursively descend as appropriate ensuring that all parts not part of the message content
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are added to the list of files to be attached. To cater for the possibility of text/plain and text/html parts
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that are further down in the multipart heirarchy than the ones that ones meant to provide that content,
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iterators are selectively used.
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:param part: the email MIME part to be processed
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:param files: any MIME part content or MIME parts to be attached are added to this list
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:param logger: the logger to use for this MIME part processing
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:param counter: the count of MIME parts added as attachment
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:param content_parts_excluded: the MIME part(s) that provided the message content have been excluded
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:returns the count of mime parts added as attachments and a boolean if the content parts have been excluded
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'''
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content_type = target_part.get_content_type()
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content_maintype = target_part.get_content_maintype()
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if "multipart" == content_maintype and target_part.get_content_disposition() not in ['inline', 'attachment']:
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# Cycle through all MIME parts in the email extracting the attachments that were not part of the message body
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# If this is a "related" multipart then we can use the message part excluder iterator directly
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if "multipart/related" == content_type:
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if content_parts_excluded:
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# This should really never happen in a properly constructed email message but...
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logger.warn("WARNING! Content type MIME parts have been excluded but a multipart/related has been encountered. there may be missing information in attachments.")
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else:
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content_parts_excluded = True
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# Use the iterator that automatically excludes message content parts
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for part in target_part.iter_attachments():
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counter, content_parts_excluded = extract_attachments(part, files, logger, counter, content_parts_excluded)
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# The iterator must be different depending on whether we have already excluded message content parts
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else:
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# Content part might be 1 or 2 parts but will be at same level so track finding at least 1
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content_part_detected = False
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for part in target_part.iter_parts():
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if not content_parts_excluded and part.get_content_type() in ["text/plain", "text/html"]:
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content_part_detected = True
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continue
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# Recurse into the part to process embedded parts
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counter, content_parts_excluded = extract_attachments(part, files, logger, counter, content_parts_excluded)
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# If we have found 1 or more content parts then flag that the content parts have been ommitted
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# to ensure that other text/* parts are attached
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if content_part_detected:
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content_parts_excluded = True
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else:
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process_as_attachment(target_part, counter, files, logger)
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counter = counter + 1
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return (counter, content_parts_excluded)
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def extract_email_metadata(message: str,
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queue: Queue,
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logger: logging.Logger
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@ -789,18 +910,19 @@ def extract_email_metadata(message: str,
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stored in the ticket if it is a new ticket by setting it to True.
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In this scenario, if it is a reply that is a forwarded message with no actual message,
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then the description will be sourced from the text/html part and the forwarded message
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will be in the FollowUp record aassociated with the ticket.
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will be in the FollowUp record associated with the ticket.
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It will iterate over every MIME part and store all MIME parts as attachments apart
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from the text/plain part.
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There may be a case for trying to exclude repeated signature images by checking if an
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attachment of the same name already exists as an attachement on the ticket but that is
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attachment of the same name already exists as an attachment on the ticket but that is
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not implemented.
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:param message: the raw email message received
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:param queue: the queue that hte
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:param queue: the queue that the message is assigned to
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:param logger: the logger to be used
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'''
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# 'message' must be an RFC822 formatted message to correctly parse.
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message_obj: Message = email.message_from_string(message)
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# NBot sure why but policy explicitly set to default is required for any messages with attachments in them
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message_obj: EmailMessage = email.message_from_string(message, EmailMessage, policy=policy.default)
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subject = extract_email_subject(message_obj)
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@ -822,84 +944,21 @@ def extract_email_metadata(message: str,
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subject,
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logger
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)
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plain_body: str = None
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formatted_body: str = None
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counter = 0
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files = []
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first_mime_non_multipart_content: MIMEText = None
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# Cycle through all MIME parts in the email extracting the plain and formatted messages
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# Algorithm uses the first text parts found as the actual email content and subsequent text parts
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# are made into attachments so they do not get lost
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for part in message_obj.walk():
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part_main_type = part.get_content_maintype()
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if part_main_type == 'multipart':
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continue
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if part.get_content_disposition() in ['inline', 'attachment']:
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process_as_attachment(part, counter, files, logger)
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else:
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# Get the content then assign to plain for formatted email message otherwise store the
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# content as an attachment
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mime_content = extract_mime_content(part)
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if first_mime_non_multipart_content is None:
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first_mime_non_multipart_content = mime_content
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if part_main_type == 'text':
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# Could be the body of the email
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part_sub_type = part.get_content_subtype()
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if plain_body is None and part_sub_type == "plain":
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plain_body = mime_content
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elif formatted_body is None and part_sub_type == "html":
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formatted_body = mime_content
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if "<body" not in formatted_body:
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email_body = f"<body>{formatted_body}</body>"
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else:
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email_body = formatted_body
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payload = (
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'<html>'
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'<head>'
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'<meta charset="utf-8" />'
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'</head>'
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'%s'
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'</html>'
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) % email_body
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files.append(
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SimpleUploadedFile(
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HTML_EMAIL_ATTACHMENT_FILENAME, payload.encode("utf-8"), 'text/html')
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)
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else:
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# Theoretically should not happen to properly structured emails but process anything
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# else as an attachment
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process_as_attachment(part, counter, files, logger)
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logger.debug(f"Text MIME part added as attachment: {part.get_content_type()}")
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else:
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# process anything else as an attachment
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process_as_attachment(part, counter, files, logger)
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counter += 1
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# Check if we have at least the plain body
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if not plain_body:
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if formatted_body:
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# We have a formatted body but no plain text body
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plain_body, _x = attempt_body_extract_from_html(formatted_body)
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else:
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# Something wrong with email or a processing issue so try first part or save full email message
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if first_mime_non_multipart_content:
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plain_body = extract_email_message(first_mime_non_multipart_content, True, True)
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else:
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plain_body = message
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# first message in thread, we save full body to avoid losing forwards and things like that
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include_chained_msgs = True if ticket_id is None and getattr(
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django_settings, 'HELPDESK_FULL_FIRST_MESSAGE_FROM_EMAIL', False) else False
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message_body = extract_email_message(plain_body, True, include_chained_msgs)
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# Only need the full message if the message_body excludes the chained messages
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chained_email_message = None if include_chained_msgs else plain_body
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# Not sure this is valid but a unit test uses a DIFFERENT plain text to html text body
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# where plain text has blank message with forwarded message so.... hack away to support it
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if message_body is not None and len(message_body) == 0 and formatted_body and len(formatted_body) > 0:
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message_body, _x = attempt_body_extract_from_html(formatted_body)
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# Set the chained message to the orignal plain text full message so it is stored in a FollowUp comments field
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if len(plain_body) > 0:
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chained_email_message = plain_body
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filtered_body, full_body = extract_email_message_content(message_obj, files, include_chained_msgs)
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# If the base part is not a multipart then it will have already been processed as the vbody content so
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# no need to process attachments
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if "multipart" == message_obj.get_content_maintype():
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# Find and attach all other parts or part contents as attachments
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counter, content_parts_excluded = extract_attachments(message_obj, files, logger)
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if not content_parts_excluded:
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# Unexpected situation and may mean there is a hole in the email processing logic
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logger.warning("Failed to exclude email content when parsing all MIME parts in the multipart. Verify that there were no text/* parts containing message content.")
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if logger.isEnabledFor(logging.DEBUG):
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logger.debug("Email parsed and %s attachments were found and attached.", counter)
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add_file_if_always_save_incoming_email_message(files, message)
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smtp_priority = message_obj.get('priority', '')
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@ -909,8 +968,8 @@ def extract_email_metadata(message: str,
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smtp_priority, smtp_importance} else 3
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payload = {
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'body': message_body,
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'full_body': chained_email_message,
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'body': filtered_body,
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'full_body': full_body,
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'subject': subject,
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'queue': queue,
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'sender_email': sender_email,
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