- detect and break email loops [SF#640854]

Author: Richard Jones

CHANGES.txt

@@ -16,6 +16,7 @@ are given with the most recent entry first.
 - removed FILTER_POSITION from bundled configs
 - reverse message listing in issue display (reversion of recent change)
 - bad entries for multilink editing in cgi don't traceback now (sf bug 640310)
+- detect and break email loops (sf bug 640854)
 
 
 2002-11-07 0.5.2

roundup/mailgw.py

@@ -73,7 +73,7 @@ class node. Any parts of other types are each stored in separate files
 an exception, the original message is bounced back to the sender with the
 explanatory message given in the exception. 
 
-$Id: mailgw.py,v 1.100 2002-12-10 00:11:15 richard Exp $
+$Id: mailgw.py,v 1.101 2002-12-10 00:23:35 richard Exp $
 '''
 
 import string, re, os, mimetools, cStringIO, smtplib, socket, binascii, quopri
@@ -92,6 +92,10 @@ class MailUsageError(ValueError):
 class MailUsageHelp(Exception):
     pass
 
+class MailLoop(Exception):
+    ''' We've seen this message before... '''
+    pass
+
 class Unauthorized(Exception):
     """ Access denied """
 
@@ -270,8 +274,12 @@ def handle_Message(self, message):
                 m = ['']
                 m.append(str(value))
                 m = self.bounce_message(message, sendto, m)
+            except MailLoop:
+                # XXX we should use a log file here...
+                return
             except:
                 # bounce the message back to the sender with the error message
+                # XXX we should use a log file here...
                 sendto = [sendto[0][1], self.instance.config.ADMIN_EMAIL]
                 m = ['']
                 m.append('An unexpected error occurred during the processing')
@@ -285,6 +293,7 @@ def handle_Message(self, message):
                 m = self.bounce_message(message, sendto, m)
         else:
             # very bad-looking message - we don't even know who sent it
+            # XXX we should use a log file here...
             sendto = [self.instance.config.ADMIN_EMAIL]
             m = ['Subject: badly formed message from mail gateway']
             m.append('')
@@ -319,6 +328,7 @@ def bounce_message(self, message, sendto, error,
         '''
         msg = cStringIO.StringIO()
         writer = MimeWriter.MimeWriter(msg)
+        writer.addheader('X-Roundup-Loop', 'hello')
         writer.addheader('Subject', subject)
         writer.addheader('From', '%s <%s>'% (self.instance.config.TRACKER_NAME,
             self.instance.config.TRACKER_EMAIL))
@@ -371,6 +381,10 @@ def handle_message(self, message):
 
         Parse the message as per the module docstring.
         '''
+        # detect loops
+        if message.getheader('x-roundup-loop', ''):
+            raise MailLoop
+
         # handle the subject line
         subject = message.getheader('subject', '')
 

roundup/roundupdb.py

@@ -15,7 +15,7 @@
 # BASIS, AND THERE IS NO OBLIGATION WHATSOEVER TO PROVIDE MAINTENANCE,
 # SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 # 
-# $Id: roundupdb.py,v 1.73 2002-11-05 22:59:46 richard Exp $
+# $Id: roundupdb.py,v 1.74 2002-12-10 00:23:36 richard Exp $
 
 __doc__ = """
 Extending hyperdb with types specific to issue-tracking.
@@ -239,6 +239,9 @@ def send_message(self, nodeid, msgid, note, sendto):
         # add a uniquely Roundup header to help filtering
         writer.addheader('X-Roundup-Name', self.db.config.TRACKER_NAME)
 
+        # avoid email loops
+        writer.addheader('X-Roundup-Loop', 'hello')
+
         # attach files
         if message_files:
             part = writer.startmultipartbody('mixed')