feature: do not allow to send unencrypted for specified (mandatory tls) domains

posttls/core/admin.py

@@ -1,7 +1,7 @@
 from django.contrib import admin
 from django.contrib.auth.admin import UserAdmin
 
-from .models import User, TLSNotification, TLSLogEntry
+from .models import User, TLSNotification, TLSLogEntry, MandatoryTLSDomains
 
 
 # Custom User Model
@@ -20,6 +20,10 @@ class TLSLogEntryAdmin(admin.ModelAdmin):
     list_display = ('queue_id', 'sender', 'recipients', 'action', 'date')
 
 
+class MandatoryTLSDomainsAdmin(admin.ModelAdmin):
+    list_display = ('domain',)
+
+
 admin.site.register(TLSNotification, TLSNotificationAdmin)
 admin.site.register(TLSLogEntry, TLSLogEntryAdmin)
-
+admin.site.register(MandatoryTLSDomains, MandatoryTLSDomainsAdmin)

posttls/core/management/commands/process_queue.py

@@ -9,10 +9,15 @@ import sys
 import datetime
 from email.header import decode_header
 
-from core.models import TLSNotification
+from core.models import TLSNotification, MandatoryTLSDomains
 
 
-def send_mail(message):
+def send_mail(message, deleted):
+    """
+    Send mail notification to sender.
+    If the domain of a recipient is listed in MandatoryTLSDomains,
+    the mail was deleted and 'deleted' is set to True.
+    """
     import smtplib
     from email.mime.multipart import MIMEMultipart
     from email.mime.text import MIMEText
@@ -34,7 +39,8 @@ def send_mail(message):
                                      'subject': message['subject'],
                                      'queue_id': message['queue_id'],
                                      'postfix_sysadmin_mail_address': settings.POSTTLS_NOTIFICATION_SYSADMIN_MAIL_ADDRESS,
-                                     'postfix_tls_host': settings.POSTTLS_TLS_HOST})
+                                     'postfix_tls_host': settings.POSTTLS_TLS_HOST,
+                                     'deleted': deleted})
 
     text_content = strip_tags(html_content)  # this strips the html tags
 
@@ -174,28 +180,46 @@ class Command(BaseCommand):
                 # set the subject
                 message['subject'] = str(subject)
 
-                #######################################################################
-                # Send notification and handle database entry
-
-                # Check the database if an earlier notification was already sent
-                try:
-                    notification = TLSNotification.objects.get(queue_id=message["queue_id"])
-                except:
-                    notification = ""
-
-                if not notification:
-                    # If this is the first notification, send it and make a database entry
-                    n = TLSNotification(queue_id=message["queue_id"], notification=datetime.datetime.today())
-                    n.save()
-                    send_mail(message)
-                else:
-                    # If the last notification is more than 30 minutes ago,
-                    # send another notification
-                    if notification.notification.replace(tzinfo=None) \
-                            < datetime.datetime.today() - datetime.timedelta(minutes=30):
-                        notification.delete()
+                ###################################################################
+                # If the domain is listed in MandatoryTLSDomains, delete the mail and inform the sender
+                mandatory_tls = False
+                mandatory_tls_domains = MandatoryTLSDomains.objects.all()
+                for domain in mandatory_tls_domains:
+                    if domain.domain in message["recipients"]:
+                        mandatory_tls = True
+
+                if mandatory_tls:
+                    # delete mail
+                    p = subprocess.Popen(['sudo', 'postsuper', '-d', message['queue_id']],
+                                         stdin=subprocess.PIPE,
+                                         stdout=subprocess.PIPE,
+                                         stderr=subprocess.STDOUT)
+                    output = str(p.stdout.read(), "utf-8").splitlines()
+
+                    # send notification to sender
+                    send_mail(message, deleted=True)
+
+                else:  # if not mandatory_tls
+                    #######################################################################
+                    # Send notification and handle database entry
+
+                    # Check the database if an earlier notification was already sent
+                    try:
+                        notification = TLSNotification.objects.get(queue_id=message["queue_id"])
+                    except:
+                        notification = ""
+
+                    if not notification:
+                        # If this is the first notification, send it and make a database entry
                         n = TLSNotification(queue_id=message["queue_id"], notification=datetime.datetime.today())
                         n.save()
-                        send_mail(message)
-
-        self.stdout.write('Successfully processed Postfix Queue!')
+                        send_mail(message, deleted=False)
+                    else:
+                        # If the last notification is more than 30 minutes ago,
+                        # send another notification
+                        if notification.notification.replace(tzinfo=None) \
+                                    < datetime.datetime.today() - datetime.timedelta(minutes=30):
+                            notification.delete()
+                            n = TLSNotification(queue_id=message["queue_id"], notification=datetime.datetime.today())
+                            n.save()
+                            send_mail(message, deleted=False)

posttls/core/migrations/0006_mandatorytlsdomains.py

@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9.2 on 2016-02-28 15:55
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0005_auto_20160228_1615'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='MandatoryTLSDomains',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('domain', models.CharField(max_length=100, verbose_name='Domain')),
+            ],
+        ),
+    ]

posttls/core/models.py

@@ -32,4 +32,13 @@ class TLSLogEntry(models.Model):
     date = models.DateTimeField('Date')
 
     def __str__(self):
-        return self.queue_id
+        return self.queue_id
+
+
+class MandatoryTLSDomains(models.Model):
+    """For these domains the user shouln't be allowed to send emails unencrypted"""
+
+    domain = models.CharField('Domain', max_length=100)
+
+    def __str__(self):
+        return self.domain

posttls/core/templates/core/mail_template.html

@@ -13,16 +13,23 @@
                 <li style='font-size: 14px;'>Subject: {{ subject }}</li>
             </ul>
 
-            <p style="font-size: 14px;">Please tell me how you want me to handle this case:</p>
+            {% if deleted %}
+                <p style="font-size: 14px;">Since our company policy requires TLS
+                    encryption for the recipient(s) mentioned above, your mail was deleted.
+                    Please find a different - and secure - channel for communication.</p>
+            {% else %}
 
-            <p>
-                <a href='https://{{postfix_tls_host}}:8080/?queue_id={{queue_id}}&action=redirect' style='text-decoration: none;'>
-                    <button style="font-size: 14px; color: white; cursor: pointer; margin-left: 0px; margin-top: 10px; color: white; border: 0; border-radius: 4px; text-shadow: 0 1px 1px rgba(0, 0, 0, 0.2); background: rgb(223, 166, 53); padding: 10px;">Send unencrypted</button>
-                </a>
-                <a href='https://{{postfix_tls_host}}:8080/?queue_id={{queue_id}}&action=delete' style='text-decoration: none;'>
-                    <button style="font-size: 14px; color: white; cursor: pointer; margin-left: 0px; margin-top: 10px; color: white; border: 0; border-radius: 4px; text-shadow: 0 1px 1px rgba(0, 0, 0, 0.2); background: rgb(28, 184, 65); padding: 10px;">Delete message</button>
-                </a>
-            </p>
+                <p style="font-size: 14px;">Please tell me how you want me to handle this case:</p>
+
+                <p>
+                    <a href='https://{{postfix_tls_host}}:8080/?queue_id={{queue_id}}&action=redirect' style='text-decoration: none;'>
+                        <button style="font-size: 14px; color: white; cursor: pointer; margin-left: 0px; margin-top: 10px; color: white; border: 0; border-radius: 4px; text-shadow: 0 1px 1px rgba(0, 0, 0, 0.2); background: rgb(223, 166, 53); padding: 10px;">Send unencrypted</button>
+                    </a>
+                    <a href='https://{{postfix_tls_host}}:8080/?queue_id={{queue_id}}&action=delete' style='text-decoration: none;'>
+                        <button style="font-size: 14px; color: white; cursor: pointer; margin-left: 0px; margin-top: 10px; color: white; border: 0; border-radius: 4px; text-shadow: 0 1px 1px rgba(0, 0, 0, 0.2); background: rgb(28, 184, 65); padding: 10px;">Delete message</button>
+                    </a>
+                </p>
+            {% endif %}
 
             <p style='font-size: 14px; margin-top: 25px;'>If you have any questions, please contact your <a href="mailto:{{postfix_sysadmin_mail_address}}" style="color: black;">System Administrator</a>.</p>
         </td>