1 files changed, 52 insertions, 0 deletions
diff --git a/src/infra.gentoo.org/milters/subscribed.py b/src/infra.gentoo.org/milters/subscribed.py
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+++ b/src/infra.gentoo.org/milters/subscribed.py
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+"""Reject messages at RCPT_TO time if the envelop sender is not subscribed.
+
+Gentoo's mlmmj is configured to silently drop messages if the poster is not
+subscribed (including no bounces) to prevent backscatter. This milter is
+intended to work around this problem by rejecting messages at message-send
+time. We do this by:
+
+    - Looking at RCPT TO headers to see where the message is headed.
+    - If its an mlmmj list, checking the subscriber list.
+    - If the envelop sender is not subscribed, reject the message rather
+       than accepting it for delivery.
+
+This is accomplished with a sendmail compatible milter that receives
+callbacks for every message seen by postfix and computing some extra logic
+to enforce these rules.
+"""
+
+import os
+import Milter
+import mlmmj
+
+def SubscribedMilterFactory():
+    """Return a SubscribedMilter with a MlmmjSource configured."""
+    inst = mlmmj.GetSingletonConfig()
+    return SubscribedMilter(mlmmj_config=inst)
+
+
+class SubscribedMilter(Milter.Base):
+    """Rejects messages at accept time if address is not subscribed."""
+
+    def __init__(self, mlmmj_config):
+        self.mlmmj_config = mlmmj_config
+
+    def envfrom(self, mailfrom, *args):
+        # Store the envelope sender for later computation
+        self.mailfrom = mailfrom
+        return Milter.CONTINUE
+
+    def envrcpt(self, to, *args):
+        if mlmmj_config.IsMailingList(to):
+            if mlmmj_config.IsSubscribed(self.mailfrom, to):
+                return Milter.ACCEPT
+            else:
+                self.setreply('550', '5.7.1',
+                        '%s is not a subscriber to %d; please subscribe to send messages to this list.' %(self.mailfrom, to))
+                return Milter.REJECT
+
+if __name__ == "__main__":
+    socketname = "/var/run/mlmmj-milter.sock"
+    timeout = 600
+    Milter.factory = SubscribedMilterFactory
+    Milter.runmilter("MlmmjMilter", socketname, timeout)