RAHHH

backend/lib/python3.12/site-packages/twisted/mail/bounce.py

@@ -0,0 +1,107 @@
+# -*- test-case-name: twisted.mail.test.test_bounce -*-
+#
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+
+"""
+Support for bounce message generation.
+"""
+import email.utils
+import os
+import time
+from io import SEEK_END, SEEK_SET, StringIO
+
+from twisted.mail import smtp
+
+BOUNCE_FORMAT = """\
+From: postmaster@{failedDomain}
+To: {failedFrom}
+Subject: Returned Mail: see transcript for details
+Message-ID: {messageID}
+Content-Type: multipart/report; report-type=delivery-status;
+    boundary="{boundary}"
+
+--{boundary}
+
+{transcript}
+
+--{boundary}
+Content-Type: message/delivery-status
+Arrival-Date: {ctime}
+Final-Recipient: RFC822; {failedTo}
+"""
+
+
+def generateBounce(message, failedFrom, failedTo, transcript="", encoding="utf-8"):
+    """
+    Generate a bounce message for an undeliverable email message.
+
+    @type message: a file-like object
+    @param message: The undeliverable message.
+
+    @type failedFrom: L{bytes} or L{unicode}
+    @param failedFrom: The originator of the undeliverable message.
+
+    @type failedTo: L{bytes} or L{unicode}
+    @param failedTo: The destination of the undeliverable message.
+
+    @type transcript: L{bytes} or L{unicode}
+    @param transcript: An error message to include in the bounce message.
+
+    @type encoding: L{str} or L{unicode}
+    @param encoding: Encoding to use, default: utf-8
+
+    @rtype: 3-L{tuple} of (E{1}) L{bytes}, (E{2}) L{bytes}, (E{3}) L{bytes}
+    @return: The originator, the destination and the contents of the bounce
+        message.  The destination of the bounce message is the originator of
+        the undeliverable message.
+    """
+
+    if isinstance(failedFrom, bytes):
+        failedFrom = failedFrom.decode(encoding)
+
+    if isinstance(failedTo, bytes):
+        failedTo = failedTo.decode(encoding)
+
+    if not transcript:
+        transcript = """\
+I'm sorry, the following address has permanent errors: {failedTo}.
+I've given up, and I will not retry the message again.
+""".format(
+            failedTo=failedTo
+        )
+
+    failedAddress = email.utils.parseaddr(failedTo)[1]
+    data = {
+        "boundary": "{}_{}_{}".format(time.time(), os.getpid(), "XXXXX"),
+        "ctime": time.ctime(time.time()),
+        "failedAddress": failedAddress,
+        "failedDomain": failedAddress.split("@", 1)[1],
+        "failedFrom": failedFrom,
+        "failedTo": failedTo,
+        "messageID": smtp.messageid(uniq="bounce"),
+        "message": message,
+        "transcript": transcript,
+    }
+
+    fp = StringIO()
+    fp.write(BOUNCE_FORMAT.format(**data))
+    orig = message.tell()
+    message.seek(0, SEEK_END)
+    sz = message.tell()
+    message.seek(orig, SEEK_SET)
+    if sz > 10000:
+        while 1:
+            line = message.readline()
+            if isinstance(line, bytes):
+                line = line.decode(encoding)
+            if len(line) <= 0:
+                break
+            fp.write(line)
+    else:
+        messageContent = message.read()
+        if isinstance(messageContent, bytes):
+            messageContent = messageContent.decode(encoding)
+        fp.write(messageContent)
+    return b"", failedFrom.encode(encoding), fp.getvalue().encode(encoding)