Files
zulip/zerver/management/commands/email_server.py
Alex Vandiver 1f0cfd4662 email-mirror: Add a standalone server that processes incoming email.
Using postfix to handle the incoming email gateway complicates things
a great deal:

- It cannot verify that incoming email addresses exist in Zulip before
  accepting them; it thus accepts mail at the `RCPT TO` stage which it
  cannot handle, and thus must reject after the `DATA`.

- It is built to handle both incoming and outgoing email, which
  results in subtle errors (1c17583ad5, 79931051bd, a53092687e,
  #18600).

- Rate-limiting happens much too late to avoid denial of
  service (#12501).

- Mis-configurations of the HTTP endpoint can break incoming
  mail (#18105).

Provide a replacement SMTP server which accepts incoming email on port
25, verifies that Zulip can accept the address, and that no
rate-limits are being broken, and then adds it directly to the
relevant queue.

Removes an incorrect comment which implied that missed-message
addresses were only usable once.  We leave rate-limiting to only
channel email addresses, since missed-message addresses are unlikely
to be placed into automated systems, as channel email addresses are.

Also simplifies #7814 somewhat.
2025-05-19 16:39:44 -07:00

74 lines
2.6 KiB
Python

import os
import ssl
from typing import Any
from urllib.parse import SplitResult
from django.core.management.base import BaseCommand, CommandParser
from typing_extensions import override
from zerver.lib.email_mirror_server import run_smtp_server
class Command(BaseCommand):
help = """SMTP server to ingest incoming emails"""
@override
def add_arguments(self, parser: CommandParser) -> None:
parser.add_argument(
"--listen", help="[Port, or address:port, to bind HTTP server to]", default="0.0.0.0:25"
)
parser.add_argument(
"--user",
help="User to drop privileges to, if started as root.",
type=str,
required=(os.geteuid() == 0),
)
parser.add_argument(
"--group",
help="Group to drop privileges to, if started as root.",
type=str,
required=(os.geteuid() == 0),
)
tls_cert: str | None = None
tls_key: str | None = None
if os.access("/etc/ssl/certs/zulip.combined-chain.crt", os.R_OK) and os.access(
"/etc/ssl/private/zulip.key", os.R_OK
):
tls_cert = "/etc/ssl/certs/zulip.combined-chain.crt"
tls_key = "/etc/ssl/private/zulip.key"
elif os.access("/etc/ssl/certs/ssl-cert-snakeoil.pem", os.R_OK) and os.access(
"/etc/ssl/private/ssl-cert-snakeoil.key", os.R_OK
):
tls_cert = "/etc/ssl/certs/ssl-cert-snakeoil.pem"
tls_key = "/etc/ssl/private/ssl-cert-snakeoil.key"
parser.add_argument(
"--tls-cert",
help="Path to TLS certificate chain file",
type=str,
default=tls_cert,
)
parser.add_argument(
"--tls-key",
help="Path to TLS private key file",
type=str,
default=tls_key,
)
@override
def handle(self, *args: Any, **options: Any) -> None:
listen = options["listen"]
if listen.isdigit():
host, port = "0.0.0.0", int(listen) # noqa: S104
else:
r = SplitResult("", listen, "", "", "")
if r.port is None:
raise RuntimeError(f"{listen!r} does not have a valid port number.")
host, port = r.hostname or "0.0.0.0", r.port # noqa: S104
if options["tls_cert"] and options["tls_key"]:
tls_context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
tls_context.load_cert_chain(options["tls_cert"], options["tls_key"])
else:
tls_context = None
run_smtp_server(options["user"], options["group"], host, port, tls_context)