do_child(): Use a slightly different algorithm for munging the

Message-ID: header in posted messages.  We define a machine parsable
format containing the listname and the hostname, and if these match
our list's name and hostname, we do not munge the header.

This continues to allow crossposting to multiple gated mailing lists,
but should break loops involving the nntpd in the most common case.

Thanks to Jim Tittsler for pointing out the problem.

1 files changed, 26 insertions, 5 deletions

diff --git a/Mailman/Handlers/ToUsenet.py b/Mailman/Handlers/ToUsenet.py
index ec84849c6..a1ebbbaab 100644
--- a/Mailman/Handlers/ToUsenet.py
+++ b/Mailman/Handlers/ToUsenet.py
@@ -101,11 +101,32 @@ def do_child(mlist, msg):
     else:
         # Newsgroups: isn't in the message
         msg.headers.append('Newsgroups: %s\n' % mlist.linked_newsgroup)
-    # Note: Need to be sure 2 messages aren't ever sent to the same
-    # list in the same process, since message ID's need to be unique.
-    # Could make the ID be mm.listname.postnum instead if that happens
-    msg['Message-ID'] = '<mailman.%s.%s@%s>\n' % (
-        time.time(), os.getpid(), mlist.host_name)
+    #
+    # Note: We need to be sure two messages aren't ever sent to the same list
+    # in the same process, since message ids need to be unique.  Further, if
+    # messages are crossposted to two Usenet-gated mailing lists, they each
+    # need to have unique message ids or the nntpd will only accept one of
+    # them.  The solution here is to substitute any existing message-id that
+    # isn't ours with one of ours, so we need to parse it to be sure we're not
+    # looping.
+    #
+    # Our Message-ID format is <mailman.secs.pid.listname@hostname>
+    msgid = msg.get('message-id')
+    hackmsgid = 1
+    if msgid:
+        mo = re.search(
+            msgid,
+            r'<mailman.\d+.\d+.(?P<listname>[^@]+)@(?P<hostname>[^>]+)>')
+        if mo:
+            lname, hname = mo.group('listname', 'hostname')
+            if lname == mlist.internal_name() and hname == mlist.host_name:
+                hackmsgid = 0
+    if hackmsgid:
+        del msg['message-id']
+        msg['Message-ID'] = '<mailman.%d.%d.%s@%s>' % (
+            time.time(), os.getpid(), mlist.internal_name(), mlist.host_name)
+    #
+    # Lines: is useful
     if msg.getheader('Lines') is None:
         msg.headers.append('Lines: %s\n' % 
                            len(string.split(msg.body,"\n")))