SMTP forwarding service

Dockerfile

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+FROM python:alpine
+
+WORKDIR /usr/src/app
+RUN pip install --no-cache requests configargparse xdg https://github.com/aio-libs/aiosmtpd/archive/refs/heads/master.zip
+COPY ./mailforward.py .
+CMD ["python", "/usr/src/app/mailforward.py"]

libertyforward.py

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+import requests
+from asyncio import new_event_loop
+from aiosmtpd.controller import UnthreadedController as Controller
+from configargparse import ArgParser
+from xdg import xdg_config_home
+
+
+def parse_args():
+    parser = ArgParser(default_config_files=['/etc/libertyforward/*.conf',
+                                             str(xdg_config_home() / 'LibertyTechForce' / 'libertyforward.conf')])
+    parser.add('-c', '--config', is_config_file=True, help='config file path', env_var='LF_CONFIG_FILE')
+    parser.add('--mailer', help='name of the mailer backend to use', env_var='LF_MAILER')
+    parser.add('--api-token', help='token to use to authenticate against API', env_var='LF_API_TOKEN')
+    return parser.parse_args()
+
+
+class MailerHandlerMixin:
+    """Base class for the mail handlers"""
+    _api_token = None
+
+    @property
+    def api_token(self):
+        return self._api_token
+
+    @api_token.setter
+    def api_token(self, value):
+        self._api_token = value
+
+
+class KingMailerHandler(MailerHandlerMixin):
+
+    async def handle_DATA(self, server, session, envelope):
+        payload = {
+            'mail_from': envelope.mail_from,
+            'rcpt_to': envelope.rcpt_tos,
+            'data': envelope.content
+        }
+        headers = {'X-Server-API-Key': self.api_token}
+        response = requests.post('https://api.kingmailer.co/api/v1/send/raw', data=payload, headers=headers)
+        if response.ok:
+            return '250 Message accepted for delivery'
+        else:
+            return '500 Could not process your message'
+
+
+if __name__ == '__main__':
+    args = parse_args()
+    loop = new_event_loop()
+    handler = KingMailerHandler()
+    handler.api_token = args.api_token
+    controller = Controller(handler, hostname='127.0.0.1', port=25, loop=loop)
+    controller.begin()
+    loop.run_forever()