import json from datetime import datetime import hashlib import hmac from django.utils.crypto import constant_time_compare from django.utils.timezone import utc from .base import AnymailBaseWebhookView from ..exceptions import AnymailWebhookValidationFailure, AnymailInvalidAddress from ..inbound import AnymailInboundMessage from ..signals import inbound, tracking, AnymailInboundEvent, AnymailTrackingEvent, EventType, RejectReason from ..utils import get_anymail_setting, combine, querydict_getfirst, parse_single_address class MailgunBaseWebhookView(AnymailBaseWebhookView): """Base view class for Mailgun webhooks""" esp_name = "Mailgun" warn_if_no_basic_auth = False # because we validate against signature api_key = None # (Declaring class attr allows override by kwargs in View.as_view.) def __init__(self, **kwargs): api_key = get_anymail_setting('api_key', esp_name=self.esp_name, kwargs=kwargs, allow_bare=True) self.api_key = api_key.encode('ascii') # hmac.new requires bytes key in python 3 super(MailgunBaseWebhookView, self).__init__(**kwargs) def validate_request(self, request): super(MailgunBaseWebhookView, self).validate_request(request) # first check basic auth if enabled if request.content_type == "application/json": # New-style webhook: json payload with separate signature block try: event = json.loads(request.body.decode('utf-8')) signature_block = event['signature'] token = signature_block['token'] timestamp = signature_block['timestamp'] signature = signature_block['signature'] except (KeyError, ValueError, UnicodeDecodeError) as err: raise AnymailWebhookValidationFailure( "Mailgun webhook called with invalid payload format", raised_from=err) else: # Legacy webhook: signature fields are interspersed with other POST data try: # Must use the *last* value of these fields if there are conflicting merged user-variables. # (Fortunately, Django QueryDict is specced to return the last value.) token = request.POST['token'] timestamp = request.POST['timestamp'] signature = str(request.POST['signature']) # force to same type as hexdigest() (for python2) except KeyError: raise AnymailWebhookValidationFailure("Mailgun webhook called without required security fields") expected_signature = hmac.new(key=self.api_key, msg='{}{}'.format(timestamp, token).encode('ascii'), digestmod=hashlib.sha256).hexdigest() if not constant_time_compare(signature, expected_signature): raise AnymailWebhookValidationFailure("Mailgun webhook called with incorrect signature") class MailgunTrackingWebhookView(MailgunBaseWebhookView): """Handler for Mailgun delivery and engagement tracking webhooks""" signal = tracking def parse_events(self, request): if request.content_type == "application/json": esp_event = json.loads(request.body.decode('utf-8')) return [self.esp_to_anymail_event(esp_event)] else: return [self.mailgun_legacy_to_anymail_event(request.POST)] event_types = { # Map Mailgun event: Anymail normalized type 'accepted': EventType.QUEUED, # not delivered to webhooks (8/2018) 'rejected': EventType.REJECTED, 'delivered': EventType.DELIVERED, 'failed': EventType.BOUNCED, 'opened': EventType.OPENED, 'clicked': EventType.CLICKED, 'unsubscribed': EventType.UNSUBSCRIBED, 'complained': EventType.COMPLAINED, } reject_reasons = { # Map Mailgun event_data.reason: Anymail normalized RejectReason # (these appear in webhook doc examples, but aren't actually documented anywhere) "bounce": RejectReason.BOUNCED, "suppress-bounce": RejectReason.BOUNCED, "generic": RejectReason.OTHER, # ??? appears to be used for any temporary failure? } severities = { # Remap some event types based on "severity" payload field (EventType.BOUNCED, 'temporary'): EventType.DEFERRED } def esp_to_anymail_event(self, esp_event): event_data = esp_event.get('event-data', {}) event_type = self.event_types.get(event_data['event'], EventType.UNKNOWN) event_type = self.severities.get((EventType.BOUNCED, event_data.get('severity')), event_type) # Use signature.token for event_id, rather than event_data.id, # because the latter is only "guaranteed to be unique within a day". event_id = esp_event.get('signature', {}).get('token') recipient = event_data.get('recipient') try: timestamp = datetime.fromtimestamp(float(event_data['timestamp']), tz=utc) except KeyError: timestamp = None try: message_id = event_data['message']['headers']['message-id'] except KeyError: message_id = None if message_id and not message_id.startswith('<'): message_id = "<{}>".format(message_id) metadata = event_data.get('user-variables', {}) tags = event_data.get('tags', []) try: delivery_status = event_data['delivery-status'] except KeyError: description = None mta_response = None else: description = delivery_status.get('description') mta_response = delivery_status.get('message') if 'reason' in event_data: reject_reason = self.reject_reasons.get(event_data['reason'], RejectReason.OTHER) else: reject_reason = None if event_type == EventType.REJECTED: # This event has a somewhat different structure than the others... description = description or event_data.get("reject", {}).get("reason") reject_reason = reject_reason or RejectReason.OTHER if not recipient: try: to_email = parse_single_address( event_data["message"]["headers"]["to"]) except (AnymailInvalidAddress, KeyError): pass else: recipient = to_email.addr_spec return AnymailTrackingEvent( event_type=event_type, timestamp=timestamp, message_id=message_id, event_id=event_id, recipient=recipient, reject_reason=reject_reason, description=description, mta_response=mta_response, tags=tags, metadata=metadata, click_url=event_data.get('url'), user_agent=event_data.get('client-info', {}).get('user-agent'), esp_event=esp_event, ) # Legacy event handling # (Prior to 2018-06-29, these were the only Mailgun events.) legacy_event_types = { # Map Mailgun event: Anymail normalized type 'delivered': EventType.DELIVERED, 'dropped': EventType.REJECTED, 'bounced': EventType.BOUNCED, 'complained': EventType.COMPLAINED, 'unsubscribed': EventType.UNSUBSCRIBED, 'opened': EventType.OPENED, 'clicked': EventType.CLICKED, # Mailgun does not send events corresponding to QUEUED or DEFERRED } legacy_reject_reasons = { # Map Mailgun (SMTP) error codes to Anymail normalized reject_reason. # By default, we will treat anything 400-599 as REJECT_BOUNCED # so only exceptions are listed here. 499: RejectReason.TIMED_OUT, # unable to connect to MX (also covers invalid recipients) # These 6xx codes appear to be Mailgun extensions to SMTP # (and don't seem to be documented anywhere): 605: RejectReason.BOUNCED, # previous bounce 607: RejectReason.SPAM, # previous spam complaint } def mailgun_legacy_to_anymail_event(self, esp_event): # esp_event is a Django QueryDict (from request.POST), # which has multi-valued fields, but is *not* case-insensitive. # Because of the way Mailgun merges user-variables into the event, # we must generally use the *first* value of any multi-valued field # to avoid potential conflicting user-data. esp_event.getfirst = querydict_getfirst.__get__(esp_event) event_type = self.legacy_event_types.get(esp_event.getfirst('event'), EventType.UNKNOWN) timestamp = datetime.fromtimestamp(int(esp_event['timestamp']), tz=utc) # use *last* value of timestamp # Message-Id is not documented for every event, but seems to always be included. # (It's sometimes spelled as 'message-id', lowercase, and missing the .) message_id = esp_event.getfirst('Message-Id', None) or esp_event.getfirst('message-id', None) if message_id and not message_id.startswith('<'): message_id = "<{}>".format(message_id) description = esp_event.getfirst('description', None) mta_response = esp_event.getfirst('error', None) or esp_event.getfirst('notification', None) reject_reason = None try: mta_status = int(esp_event.getfirst('code')) except (KeyError, TypeError): pass except ValueError: # RFC-3463 extended SMTP status code (class.subject.detail, where class is "2", "4" or "5") try: status_class = esp_event.getfirst('code').split('.')[0] except (TypeError, IndexError): # illegal SMTP status code format pass else: reject_reason = RejectReason.BOUNCED if status_class in ("4", "5") else RejectReason.OTHER else: reject_reason = self.legacy_reject_reasons.get( mta_status, RejectReason.BOUNCED if 400 <= mta_status < 600 else RejectReason.OTHER) metadata = self._extract_legacy_metadata(esp_event) # tags are supposed to be in 'tag' fields, but are sometimes in undocumented X-Mailgun-Tag tags = esp_event.getlist('tag', None) or esp_event.getlist('X-Mailgun-Tag', []) return AnymailTrackingEvent( event_type=event_type, timestamp=timestamp, message_id=message_id, event_id=esp_event.get('token', None), # use *last* value of token recipient=esp_event.getfirst('recipient', None), reject_reason=reject_reason, description=description, mta_response=mta_response, tags=tags, metadata=metadata, click_url=esp_event.getfirst('url', None), user_agent=esp_event.getfirst('user-agent', None), esp_event=esp_event, ) def _extract_legacy_metadata(self, esp_event): # Mailgun merges user-variables into the POST fields. If you know which user variable # you want to retrieve--and it doesn't conflict with a Mailgun event field--that's fine. # But if you want to extract all user-variables (like we do), it's more complicated... event_type = esp_event.getfirst('event') metadata = {} if 'message-headers' in esp_event: # For events where original message headers are available, it's most reliable # to recover user-variables from the X-Mailgun-Variables header(s). headers = json.loads(esp_event['message-headers']) variables = [value for [field, value] in headers if field == 'X-Mailgun-Variables'] if len(variables) >= 1: # Each X-Mailgun-Variables value is JSON. Parse and merge them all into single dict: metadata = combine(*[json.loads(value) for value in variables]) elif event_type in self._known_legacy_event_fields: # For other events, we must extract from the POST fields, ignoring known Mailgun # event parameters, and treating all other values as user-variables. known_fields = self._known_legacy_event_fields[event_type] for field, values in esp_event.lists(): if field not in known_fields: # Unknown fields are assumed to be user-variables. (There should really only be # a single value, but just in case take the last one to match QueryDict semantics.) metadata[field] = values[-1] elif field == 'tag': # There's no way to distinguish a user-variable named 'tag' from an actual tag, # so don't treat this/these value(s) as metadata. pass elif len(values) == 1: # This is an expected event parameter, and since there's only a single value # it must be the event param, not metadata. pass else: # This is an expected event parameter, but there are (at least) two values. # One is the event param, and the other is a user-variable metadata value. # Which is which depends on the field: if field in {'signature', 'timestamp', 'token'}: metadata[field] = values[0] # values = [user-variable, event-param] else: metadata[field] = values[-1] # values = [event-param, user-variable] return metadata _common_legacy_event_fields = { # These fields are documented to appear in all Mailgun opened, clicked and unsubscribed events: 'event', 'recipient', 'domain', 'ip', 'country', 'region', 'city', 'user-agent', 'device-type', 'client-type', 'client-name', 'client-os', 'campaign-id', 'campaign-name', 'tag', 'mailing-list', 'timestamp', 'token', 'signature', # Undocumented, but observed in actual events: 'body-plain', 'h', 'message-id', } _known_legacy_event_fields = { # For all Mailgun event types that *don't* include message-headers, # map Mailgun (not normalized) event type to set of expected event fields. # Used for metadata extraction. 'clicked': _common_legacy_event_fields | {'url'}, 'opened': _common_legacy_event_fields, 'unsubscribed': _common_legacy_event_fields, } class MailgunInboundWebhookView(MailgunBaseWebhookView): """Handler for Mailgun inbound (route forward-to-url) webhook""" signal = inbound def parse_events(self, request): return [self.esp_to_anymail_event(request)] def esp_to_anymail_event(self, request): # Inbound uses the entire Django request as esp_event, because we need POST and FILES. # Note that request.POST is case-sensitive (unlike email.message.Message headers). esp_event = request if 'body-mime' in request.POST: # Raw-MIME message = AnymailInboundMessage.parse_raw_mime(request.POST['body-mime']) else: # Fully-parsed message = self.message_from_mailgun_parsed(request) message.envelope_sender = request.POST.get('sender', None) message.envelope_recipient = request.POST.get('recipient', None) message.stripped_text = request.POST.get('stripped-text', None) message.stripped_html = request.POST.get('stripped-html', None) message.spam_detected = message.get('X-Mailgun-Sflag', 'No').lower() == 'yes' try: message.spam_score = float(message['X-Mailgun-Sscore']) except (TypeError, ValueError): pass return AnymailInboundEvent( event_type=EventType.INBOUND, timestamp=datetime.fromtimestamp(int(request.POST['timestamp']), tz=utc), event_id=request.POST.get('token', None), esp_event=esp_event, message=message, ) def message_from_mailgun_parsed(self, request): """Construct a Message from Mailgun's "fully-parsed" fields""" # Mailgun transcodes all fields to UTF-8 for "fully parsed" messages try: attachment_count = int(request.POST['attachment-count']) except (KeyError, TypeError): attachments = None else: # Load attachments from posted files: Mailgun file field names are 1-based att_ids = ['attachment-%d' % i for i in range(1, attachment_count+1)] att_cids = { # filename: content-id (invert content-id-map) att_id: cid for cid, att_id in json.loads(request.POST.get('content-id-map', '{}')).items() } attachments = [ AnymailInboundMessage.construct_attachment_from_uploaded_file( request.FILES[att_id], content_id=att_cids.get(att_id, None)) for att_id in att_ids ] return AnymailInboundMessage.construct( headers=json.loads(request.POST['message-headers']), # includes From, To, Cc, Subject, etc. text=request.POST.get('body-plain', None), html=request.POST.get('body-html', None), attachments=attachments, )