import re
import hashlib
import hmac
import json
import logging
import base64
from django.conf import settings
from django.core.mail import EmailMultiAlternatives
from django.http import HttpRequest
from django.utils.encoding import smart_bytes
from ..backends import RequestParser
from ..errors import (
RequestParseError,
AttachmentTooLargeError,
AuthenticationError,
)
logger = logging.getLogger(__name__)
class MandrillSignatureMismatchError(AuthenticationError):
"""Error raised when the request's mandrill signature doesn't match.
"""
def __init__(self, request, expected, calculated):
super(MandrillSignatureMismatchError, self)
self.request = request
self.expected_signature = expected
self.calculated_signature = calculated
def _detect_base64(s):
"""Quite an ingenuous function to guess if a string is base64 encoded
"""
return (len(s) % 4 == 0) and re.match('^[A-Za-z0-9+/]+[=]{0,2}$', s)
def _check_mandrill_signature(request, key):
expected = request.META.get('HTTP_X_MANDRILL_SIGNATURE', None)
url = request.build_absolute_uri()
# Mandrill appends the POST params in alphabetical order of the key.
params = sorted(request.POST.items(), key=lambda x: x[0])
message = url + ''.join(key + value for key, value in params)
signed_binary = hmac.new(
key.encode('utf-8'),
message.encode('utf-8'),
hashlib.sha1,
)
signature = base64.b64encode(signed_binary.digest()).decode('utf-8')
if signature != expected:
raise MandrillSignatureMismatchError(request, expected, signature)
class MandrillRequestParser(RequestParser):
"""Mandrill request parser. """
def _process_attachments(self, email, attachments):
for key, attachment in list(attachments.items()):
is_base64 = attachment.get('base64')
name = attachment.get('name')
mimetype = attachment.get('type')
content = attachment.get('content', "")
if is_base64:
content = base64.b64decode(content)
# watchout: sometimes attachment contents are base64'd but mandrill doesn't set the flag
elif _detect_base64(content):
content = base64.b64decode(content)
content = smart_bytes(content, strings_only=True)
if len(content) > self.max_file_size:
logger.debug(
"File attachment %s is too large to process (%sB)",
name,
len(content)
)
raise AttachmentTooLargeError(
email=email,
filename=name,
size=len(content)
)
if name and mimetype and content:
email.attach(name, content, mimetype)
return email
def _get_recipients(self, array):
"""Returns an iterator of objects
in the form ["Name <address@example.com", ...]
from the array [["address@example.com", "Name"]]
"""
for address, name in array:
if not name:
yield address
else:
yield "\"%s\" <%s>" % (name, address)
def _get_sender(self, from_email, from_name=None):
if not from_name:
return from_email
else:
return "\"%s\" <%s>" % (from_name, from_email)
def parse(self, request):
"""Parse incoming request and return an email instance.
Args:
request: an HttpRequest object, containing a list of forwarded emails, as
per Mandrill specification for inbound emails.
Returns:
a list of EmailMultiAlternatives instances
"""
assert isinstance(request, HttpRequest), "Invalid request type: %s" % type(request)
if settings.INBOUND_MANDRILL_AUTHENTICATION_KEY:
_check_mandrill_signature(
request=request,
key=settings.INBOUND_MANDRILL_AUTHENTICATION_KEY,
)
try:
messages = json.loads(request.POST['mandrill_events'])
except (ValueError, KeyError) as ex:
raise RequestParseError("Request is not a valid json: %s" % ex)
if not messages:
logger.debug("No messages found in mandrill request: %s", request.body)
return []
emails = []
for message in messages:
if message.get('event') != 'inbound':
logger.debug("Discarding non-inbound message")
continue
msg = message.get('msg')
try:
from_email = msg['from_email']
to = list(self._get_recipients(msg['to']))
cc = list(self._get_recipients(msg['cc'])) if 'cc' in msg else []
bcc = list(self._get_recipients(msg['bcc'])) if 'bcc' in msg else []
subject = msg.get('subject', "")
attachments = msg.get('attachments', {})
attachments.update(msg.get('images', {}))
text = msg.get('text', "")
html = msg.get('html', "")
except (KeyError, ValueError) as ex:
raise RequestParseError(
"Inbound request is missing or got an invalid value.: %s." % ex
)
email = EmailMultiAlternatives(
subject=subject,
body=text,
from_email=self._get_sender(
from_email=from_email,
from_name=msg.get('from_name'),
),
to=to,
cc=cc,
bcc=bcc,
)
if html is not None and len(html) > 0:
email.attach_alternative(html, "text/html")
email = self._process_attachments(email, attachments)
emails.append(email)
return emails
